Showing papers in "Journal of Animal Science in 2011"

BOARD-INVITED REVIEW: opportunities and challenges in using exogenous enzymes to improve nonruminant animal production.

Abstract: Diets fed to nonruminant animals are composed mainly of feed ingredients of plant origin. A variety of antinutritional factors such as phytin, nonstarch polysaccharides, and protease inhibitors may be present in these feed ingredients, which could limit nutrients that may be utilized by animals fed such diets. The primary nutrient utilization-limiting effect of phytin arises from the binding of 6 phosphate groups, thus making the P unavailable to the animal. The negative charges allow for formation of insoluble phytin-metal complexes with many divalent cations. Furthermore, phytin and protein can form binary complexes through electrostatic links of its charged phosphate groups with either the free amino group on AA on proteins or via formation of ternary complexes of phytin, Ca(2+), and protein. The form and extent of de novo formation of binary and ternary complexes of phytin and protein are likely to be important variables that influence the effectiveness of nutrient hydrolysis in plant-based diets. Nonstarch polysacharides reduce effective energy and nutrient utilization by nonruminant animals because of a lack of the enzymes needed for breaking down the complex cell wall structure that encapsulate other nutrients. Enzymes are used in nonruminant animal production to promote growth and efficiency of nutrient utilization and reduce nutrient excretion. The enzymes used include those that target phytin and nonstarch polysaccharides. Phytase improves growth and enhances P utilization, but positive effects on other nutrients are not always observed. Nonstarch polysaccharide-hydrolyzing enzymes are less consistent in their effects on growth and nutrient utilization, although they show promise and it is imperative to closely match both types and amounts of nonstarch polysaccharides with appropriate enzyme for beneficial effects. When used together with phytase, nonstarch polysaccharide-hydrolyzing enzymes may increase the accessibility of phytase to phytin encapsulated in cell walls. The future of enzymes in nonruminant animal production is promising and will likely include an understanding of the role of enzyme supplementation in promoting health as well as how enzymes may modulate gene functions. This review is an attempt to summarize current thinking in this area, provide some clarity in nomenclature and mechanisms, and suggest opportunities for expanded exploitation of this unique biotechnology.

RUMINANT NUTRITION SYMPOSIUM: Role of fermentation acid absorption in the regulation of ruminal pH

Abstract: Highly fermentable diets are rapidly converted to organic acids [i.e., short-chain fatty acids (SCFA) and lactic acid] within the rumen. The resulting release of protons can constitute a challenge to the ruminal ecosystem and animal health. Health disturbances, resulting from acidogenic diets, are classified as subacute and acute acidosis based on the degree of ruminal pH depression. Although increased acid production is a nutritionally desired effect of increased concentrate feeding, the accumulation of protons in the rumen is not. Consequently, mechanisms of proton removal and their quantitative importance are of major interest. Saliva buffers (i.e., bicarbonate, phosphate) have long been identified as important mechanisms for ruminal proton removal. An even larger proportion of protons appears to be removed from the rumen by SCFA absorption across the ruminal epithelium, making efficiency of SCFA absorption a key determinant for the individual susceptibility to subacute ruminal acidosis. Proceeding initially from a model of exclusively diffusional absorption of fermentation acids, several protein-dependent mechanisms have been discovered over the last 2 decades. Although the molecular identity of these proteins is mostly uncertain, apical acetate absorption is mediated, to a major degree, via acetate-bicarbonate exchange in addition to another nitrate-sensitive, bicarbonate-independent transport mechanism and lipophilic diffusion. Propionate and butyrate also show partially bicarbonate-dependent transport modes. Basolateral efflux of SCFA and their metabolites has to be mediated primarily by proteins and probably involves the monocarboxylate transporter (MCT1) and anion channels. Although the ruminal epithelium removes a large fraction of protons from the rumen, it also recycles protons to the rumen via apical sodium-proton exchanger, NHE. The latter is stimulated by ruminal SCFA absorption and salivary Na(+) secretion and protects epithelial integrity. Finally, SCFA absorption also accelerates urea transport into the rumen, which via ammonium recycling, may remove protons from rumen to the blood. Ammonium absorption into the blood is also stimulated by luminal SCFA. It is suggested that the interacting transport processes for SCFA, urea, and ammonia represent evolutionary adaptations of ruminants to actively coordinate energy fermentation, protein assimilation, and pH regulation in the rumen.

The environmental impact of beef production in the United States: 1977 compared with 2007.

Abstract: Consumers often perceive that the modern beef production system has an environmental impact far greater than that of historical systems, with improved efficiency being achieved at the expense of greenhouse gas emissions. The objective of this study was to compare the environmental impact of modern (2007) US beef production with production practices characteristic of the US beef system in 1977. A deter- ministic model based on the metabolism and nutrient requirements of the beef population was used to quantify resource inputs and waste outputs per billion kilograms of beef. Both the modern and historical production sys- tems were modeled using characteristic management practices, population dynamics, and production data from US beef systems. Modern beef production requires considerably fewer resources than the equivalent sys- tem in 1977, with 69.9% of animals, 81.4% of feedstuffs, 87.9% of the water, and only 67.0% of the land required to produce 1 billion kg of beef. Waste outputs were similarly reduced, with modern beef systems produc- ing 81.9% of the manure, 82.3% CH4, and 88.0% N2O per billion kilograms of beef compared with production systems in 1977. The C footprint per billion kilograms of beef produced in 2007 was reduced by 16.3% com- pared with equivalent beef production in 1977. As the US population increases, it is crucial to continue the improvements in efficiency demonstrated over the past 30 yr to supply the market demand for safe, affordable beef while reducing resource use and mitigating envi- ronmental impact.

Ruminant Nutrition Symposium: Molecular adaptation of ruminal epithelia to highly fermentable diets.

Abstract: Feeding highly fermentable diets to ruminants is one strategy to increase energy intake. The increase in short-chain fatty acid (SCFA) production and reduced ruminal pH associated with highly fermentable diets imposes a challenge to the metabolism and the regulation of intracellular pH homeostasis of ruminal epithelia. The ruminal epithelia respond to these challenges in a coordinated manner. Whereas the enlargement of absorptive surface area is well documented, emerging evidence at the mRNA and transporter and enzyme activity levels indicate that changes in epithelial cell function may be the initial response. It is not surprising that gene expression analysis has identified pathways involved in fatty acid metabolism, ion transport, and intracellular homeostasis to be the pathways dominantly affected during adaptation and after adaptation to a highly fermentable diet. These findings are important because the intraepithelial metabolism of SCFA, particularly butyrate, helps to maintain the concentration gradient between the cytosol and lumen, thereby facilitating absorption. Butyrate metabolism also controls the intracellular availability of butyrate, which is widely regarded as a signaling molecule. Current data indicate that for butyrate metabolism, 3-hydroxy-3-methylglutaryl-CoA synthase and acetyl-CoA acetyltransferase are potential regulatory points with transient up- and downregulation during diet adaptation. In addition to nutrient transport and utilization, genes involved in the maintenance of cellular tight junction integrity and induction of inflammation have been identified as differentially expressed genes during adaptation to highly fermentable diets. This may have important implications on ruminal epithelial barrier function and the inflammatory response often associated with subacute ruminal acidosis. The objective of this review is to summarize ruminal epithelial adaptation to highly fermentable diets focusing on the changes at the enzyme and transporter activity levels, as well as the underlying molecular changes at the mRNA and protein expression levels.

Triennial Growth Symposium: important roles for L-glutamine in swine nutrition and production.

Abstract: L-Glutamine (Gln) has traditionally not been considered a nutrient needed in diets for livestock species or even mentioned in classic animal nutrition textbooks. This is due to previous technical difficulties in Gln analysis and the unsubstantiated assumption that animals can synthesize sufficient amounts of Gln to meet their needs. Consequently, the current (1998) version of NRC does not recommend dietary Gln requirements for swine. This lack of knowledge about Gln nutrition has contributed to suboptimal efficiency of global pig production. Because of recent advances in research, Gln is now known to be an abundant AA in physiological fluids and proteins and a key regulator of gene expression. Additionally, Gln can regulate cell signaling via the mammalian target of rapamycin pathway, adenosine monophosphate-activated protein kinase, extracellular signal-related kinase, Jun kinase, mitogen-activated protein kinase, and nitric oxide. The exquisite integration of Gln-dependent regulatory networks has profound effects on cell proliferation, differentiation, migration, metabolism, homeostasis, survival, and function. As a result of translating basic research into practice, dietary supplementation with 1% Gln maintains gut health and prevents intestinal dysfunction in low-birth-weight or early-weaned piglets while increasing their growth performance and survival. In addition, supplementing 1% Gln to a corn- and soybean-meal-based diet between d 90 and 114 of gestation ameliorates fetal growth retardation in gilts and reduces preweaning mortality of piglets. Furthermore, dietary supplementation with 1% Gln enhances milk production by lactating sows. Thus, adequate amounts of dietary Gln, a major nutrient, are necessary to support the maximum growth, development, and production performance of swine.

RUMINANT NUTRITION SYMPOSIUM: Productivity, digestion, and health responses to hindgut acidosis in ruminants

Abstract: Microbial fermentation of carbohy- drates in the hindgut of dairy cattle is responsible for 5 to 10% of total-tract carbohydrate digestion. When dietary, animal, or environmental factors contribute to abnormal, excessive flow of fermentable carbohydrates from the small intestine, hindgut acidosis can occur. Hindgut acidosis is characterized by increased rates of production of short-chain fatty acids including lactic acid, decreased digesta pH, and damage to gut epithe- lium as evidenced by the appearance of mucin casts in feces. Hindgut acidosis is more likely to occur in high-producing animals fed diets with relatively greater proportions of grains and lesser proportions of forage. In these animals, ruminal acidosis and poor selective retention of fermentable carbohydrates by the rumen will increase carbohydrate flow to the hindgut. In more severe situations, hindgut acidosis is characterized by an inflammatory response; the resulting breach of the barrier between animal and digesta may contribute to laminitis and other disorders. In a research setting, effects of increased hindgut fermentation have been evaluated using pulse-dose or continuous abomasal infusions of varying amounts of fermentable carbohy- drates. Continuous small-dose abomasal infusions of 1 kg/d of pectin or fructans into lactating cows resulted in decreased diet digestibility and decreased milk fat percentage without affecting fecal pH or VFA concen- trations. The decreased diet digestibility likely resulted from increased bulk in the digestive tract or from in- creased digesta passage rate, reducing exposure of the digesta to intestinal enzymes and epithelial absorptive surfaces. The same mechanism is proposed to explain the decreased milk fat percentage because only milk concentrations of long-chain fatty acids were decreased. Pulse-dose abomasal fructan infusions (1 g/kg of BW) into steers resulted in watery feces, decreased fecal pH, and increased fecal VFA concentrations, without caus- ing an inflammatory response. Daily 12-h abomasal in- fusions of a large dose of starch (~4 kg/d) have also induced hindgut acidosis as indicated by decreased fe- cal pH and watery feces. On the farm, watery or foamy feces or presence of mucin casts in feces may indicate hindgut acidosis. In summary, hindgut acidosis occurs because of relatively high rates of large intestinal fer- mentation, likely due to digestive dysfunction in other parts of the gut. A better understanding of the relation- ship of this disorder to other animal health disorders is needed.

A meta-analysis of the effects of high ambient temperature on growth performance of growing-finishing pigs.

Abstract: High ambient temperature (T) is one of the most important climatic factors influencing pig performance. Increased T occurs sporadically during summer heat waves in temperate climates and year round in tropical climates. Results of published experiments assessing the effects of high T on pig performance are surprisingly variable. Thus, a meta-analysis was performed to aggregate our knowledge and attempt to explain differences in the results across studies on the effect of increased T on ADFI and ADG in growing-finishing pigs. Data for ADFI and ADG were extracted from 86 and 80 trials, respectively, from articles published in scientific journals indexed in PubMed, Science Direct, and from proceedings of scientific meetings through November 2009. Data on ADFI and ADG were analyzed using a linear mixed model that included the linear and the quadratic effects of T and BW, and their interactions as continuous, fixed effects variables, and the trial as a random effect factor (i.e., block). In addition, the effects of housing type (2 levels: individual and group housing) and the year of publication (3 levels: 1970 to 1989, 1990 to 1999, and 2000 to 2009) on the intercept and the linear regression term for T (i.e., the slope) were also tested. Results showed that high T had a curvilinear effect on ADFI and ADG and that this effect was more pronounced in heavier pigs. Across T, ADFI was less when pigs were group-housed. The intercept and the regression coefficient (slope) for T were significantly affected by the year of publication. The effect of increased T was greater in more contemporary works, suggesting that modern genotypes could be more sensitive to heat stress than older genotypes of lesser growth potential. In conclusion, pig performance decreases at an accelerating rate as T is increased. The large between-study variability on the effects of high T on pig performance is partially explained by differences in pig BW and to a lesser extent by the year the study was published.

Board-invited review: St. Anthony's Fire in livestock: causes, mechanisms, and potential solutions.

Abstract: After a brief history of ergot alkaloids and ergotism, this review focuses on the metabolism and mechanisms of action of the ergot alkaloids. The authors provide models of how these alkaloids afflict grazing livestock under complex animal-plant/endophyte-environmental interactions. Alkaloid chemistry is presented to orient the reader to the structure-function relationships that are known to exist. Where appropriate, the medical literature is used to aid interpretation of livestock research and to provide insight into potential modes of action and alkaloid metabolism where these are not known for livestock. In closing the paper, we discuss management of ergot alkaloid intoxication in livestock and future research needs for this field of study.

Cattle temperament: persistence of assessments and associations with productivity, efficiency, carcass and meat quality traits.

Abstract: Relationships between temperament and a range of performance, carcass, and meat quality traits in young cattle were studied in 2 experiments conducted in New South Wales (NSW) and Western Australia (WA), Australia. In both experiments, growth rates of cattle were assessed during backgrounding on pasture and grain finishing in a feedlot. Carcass and objective meat quality characteristics were measured after slaughter. Feed intake and efficiency during grain finishing were also determined in NSW. Brahman (n = 82 steers and 82 heifers) and Angus (n = 25 steers and 24 heifers) cattle were used in the NSW experiment. In NSW, temperament was assessed by measuring flight speed [FS, m/s on exit from the chute (crush)] on 14 occasions, and by assessing agitation score during confinement in the crush (CS; 1 = calm to 5 = highly agitated) on 17 occasions over the course of the experiment. Brahman (n = 173) and Angus (n = 20) steers were used in the WA experiment. In WA, temperament was assessed by measuring FS on 2 occasions during backgrounding and on 2 occasions during grain feeding. At both sites, a hormonal growth promotant (Revalor-H, Virbac, Milperra, New South Wales, Australia) was applied to one-half of the cattle at feedlot entry, and the Brahman cattle were polymorphic for 2 calpain-system markers for beef tenderness. Temperament was not related (most P > 0.05) to tenderness gene marker status in Brahman cattle and was not (all P > 0.26) modified by the growth promotant treatment in either breed. The Brahman cattle had greater individual variation in, and greater correlations within and between, repeated assessments of FS and CS than did the Angus cattle. Correlations for repeated measures of FS were greater than for repeated assessments of CS, and the strength of correlations for both declined over time. Average FS or CS for each experiment and location (NSW or WA × backgrounding or finishing) were more highly correlated than individual measurements, indicating that the average values were a more reliable assessment of cattle temperament than any single measure. In Brahman cattle, increased average FS and CS were associated with significant (P < 0.05) reductions in backgrounding and feedlot growth rates, feed intake and time spent eating, carcass weight, and objective measures of meat quality. In Angus cattle, the associations between temperament and growth rates, feed intake, and carcass traits were weaker than in Brahmans, although the strength of relationships with meat quality were similar.

Genome-wide association studies for feedlot and growth traits in cattle.

Abstract: A genome wide-association study for production traits in cattle was carried out using genotype data from the 10K Affymetrix (Santa Clara, CA) and the 50K Illumina (San Diego, CA) SNP chips. The results for residual feed intake (RFI), BW, and hip height in 3 beef breed types (Bos indicus, Bos taurus, and B. indicus × B. taurus), and for stature in dairy cattle, are presented. The aims were to discover SNP associated with all traits studied, but especially RFI, and further to test the consistency of SNP effects across different cattle populations and breed types. The data were analyzed within data sets and within breed types by using a mixed model and fitting 1 SNP at a time. In each case, the number of significant SNP was more than expected by chance alone. A total of 75 SNP from the reference population with 50K chip data were significant (P < 0.001) for RFI, with a false discovery rate of 68%. These 75 SNP were mapped on 24 different BTA. Of the 75 SNP, the 9 most significant SNP were detected on BTA 3, 5, 7, and 8, with P ≤ 6.0 × 10(-5). In a population of Angus cattle divergently selected for high and low RFI and 10K chip data, 111 SNP were significantly (P < 0.001) associated with RFI, with a false discovery rate of 7%. Approximately 103 of these SNP were therefore likely to represent true positives. Because of the small number of SNP common to both the 10K and 50K SNP chips, only 27 SNP were significantly (P < 0.05) associated with RFI in the 2 populations. However, other chromosome regions were found that contained SNP significantly associated with RFI in both data sets, although no SNP within the region showed a consistent effect on RFI. The SNP effects were consistent between data sets only when estimated within the same breed type.

Amino acid digestibility in heated soybean meal fed to growing pigs.

Abstract: Heat treatment of soybean meal (SBM) is necessary to reduce the concentration of trypsin inhibitors, but excessive heat treatment may reduce AA concentration and digestibility because AA can be destroyed by the Maillard reaction. The objective of this experiment was to determine the effects of heat treatment of SBM on apparent ileal digestibility and standardized ileal digestibility (SID) of AA by growing pigs. A source of conventional dehulled SBM (48.5% CP) was divided into 4 batches. One batch was not additionally heated, 1 batch was autoclaved at 125°C for 15 min, 1 batch was autoclaved at 125°C for 30 min, and 1 batch was oven-dried at 125°C for 30 min. Four SBM-cornstarch diets were formulated, and each of the 4 batches of SBM was used as the sole source of dietary AA in 1 diet. A N-free diet was used to estimate basal endogenous losses of AA. Ten growing barrows with an initial BW of 25.3 ± 2.0 kg were individually fitted with a T-cannula in the distal ileum. Pigs were allotted to treatments in a replicated 5 × 5 balanced Latin square design with 5 diets and 5 periods. Each period lasted 7 d, and ileal digesta were collected on d 6 and 7 of each period. Results of the experiment indicated that the apparent ileal digestibility and SID of CP and all AA decreased linearly (P 0.10) the SID of CP and AA in the SBM or the furosine concentration, and the color in the oven-dried sample indicated that this sample was not heat damaged. In conclusion, the digestibility of all AA in autoclaved SBM is linearly reduced as the autoclaving time increases from 0 to 30 min. The reason for these changes is most likely that autoclaving at 125°C results in Maillard reactions in SBM.

NANOG is a key factor for induction of pluripotency in bovine adult fibroblasts.

Abstract: Since the first reports on isolation of pluripotent mouse embryonic stem (ES) cells 3 decades ago, there have been numerous attempts to derive ES cell lines from commercially important livestock species with limited success. The recent discovery that ectopic expression of a handful of stem cell-related genes was capable of inducing pluripotency in rodents and primates provided a novel approach to derivation of pluripotent stem cell lines. We used this approach in cattle and demonstrated that the ectopic expression of POU5F1 (also known as Oct4), SOX2, KLF4, and c-MYC alone was not sufficient for stable induction of pluripotency in bovine adult fibroblasts and that the additional expression of NANOG to the reprogramming cocktail was essential for the generation of stable bovine (b) induced pluripotent stem (iPS) cells. The resulting biPS cells were characterized by reverse-transcription PCR for a panel of ES marker genes. Immunocytochemical localization of POU5F1, SSEA-1, SSEA-4, and colorimetric alkaline phosphatase activity was measured in the iPS clones. The differentiation potential of the biPS cells was determined in vitro by expression of differentiation markers in embryoid bodies. Injection of biPS into immunocompromised mice resulted in teratomas containing cell types of the 3 germ lineages. This study reports the first generation of bovine induced pluripotent cell lines and paves the way for the use of biPS cells for biotechnological and agricultural purposes.

Companion animals symposium: microbes and gastrointestinal health of dogs and cats.

Abstract: Recent molecular studies have revealed complex bacterial, fungal, archaeal, and viral communities in the gastrointestinal tract of dogs and cats. More than 10 bacterial phyla have been identified, with Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria, and Actinobacteria constituting more than 99% of all gut microbiota. Microbes act as a defending barrier against invading pathogens, aid in digestion, provide nutritional support for enterocytes, and play a crucial role in the development of the immune system. Of significance for gastrointestinal health is their ability to ferment dietary substrates into short-chain fatty acids, predominantly to acetate, propionate, and butyrate. However, microbes can have also a detrimental effect on host health. Specific pathogens (e.g., Salmonella, Campylobacter jejuni, and enterotoxigenic Clostridium perfringens) have been implicated in acute and chronic gastrointestinal disease. Compositional changes in the small intestinal microbiota, potentially leading to changes in intestinal permeability and digestive function, have been suggested in canine small intestinal dysbiosis or antibiotic-responsive diarrhea. There is mounting evidence that microbes play an important role in the pathogenesis of canine and feline inflammatory bowel disease (IBD). Current theories for the development of IBD favor a combination of environmental factors, the intestinal microbiota, and a genetic susceptibility of the host. Recent studies have revealed a genetic susceptibility for defective bacterial clearance in Boxer dogs with granulomatous colitis. Differential expression of pathogen recognition receptors (i.e., Toll-like receptors) were identified in dogs with chronic enteropathies. Similarly to humans, a microbial dysbiosis has been identified in feline and canine IBD. Commonly observed microbial changes are increased Proteobacteria (i.e., Escherichia coli) with concurrent decreases in Firmicutes, especially a reduced diversity in Clostridium clusters XIVa and IV (i.e., Lachnospiraceae, Ruminococcaceae, Faecalibacterium spp.). This would indicate that these bacterial groups, important short-chain fatty acid producers, may play an important role in promoting intestinal health.

Effects of purified zearalenone on growth performance, organ size, serum metabolites, and oxidative stress in postweaning gilts.

Abstract: Zearalenone (ZEA), an estrogenic mycotoxin, is produced mainly by Fusarium fungi Previous studies indicated that acute ZEA exposure induced oxidative stress and damage in multiple organs Therefore, the present study was designed to investigate the adverse effects of dietary ZEA (11 to 32 mg/kg of diet) on oxidative stress and organ damage in postweaning gilts A total of 20 gilts (Landrace × Yorkshire × Duroc) weaned at d 21 with an average BW of 1036 ± 121 kg was used in the study Gilts were housed in a temperature-controlled room, divided into 4 treatments, and fed a basal diet only (control) or basal diet supplemented with purified ZEA at a dietary concentration of 1 (ZEA1), 2 (ZEA2), or 3 (ZEA3) mg/kg of diet for 18 d ad libitum The actual ZEA contents (analyzed) were 0, 11 ± 002, 20 ± 001, and 32 ± 002 mg/kg for control, ZEA1, ZEA2, and ZEA3, respectively Gilts fed different amounts of dietary ZEA grew similarly with no difference (P > 005) in feed intake Vulva size increased linearly over the 18 d of feeding in gilts fed diets containing 11 mg of ZEA/kg or greater (P < 0001) Relative weight of genital organs, liver, and kidney increased linearly (P < 005) in a ZEA-dose-dependent manner Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, γ-glutamate transferase, urea, and creatinine (P < 005), and malondialdehyde concentrations in both serum and liver (P < 0001) were also increased linearly in a ZEA-dose-dependent manner However, spleen relative weight (P = 0002) and activities of total superoxide dismutase and glutathione peroxidase (in both serum and liver (P < 005) were decreased linearly as dietary ZEA increased Results showed that besides genital organs, the liver, kidney, and spleen may also be target tissues in young gilts fed diets containing 11 to 32 mg of ZEA/kg for 18 d Increased key liver enzymes in the serum suggest progressive liver damage caused by feeding ZEA, and an increase in oxidative stress in gilts is another potential impact of ZEA toxicity in pigs

A genome-wide association study of meat and carcass traits in Australian cattle.

Abstract: Chromosomal regions containing DNA variation affecting the traits intramuscular fat percentage (IMF), meat tenderness measured as peak force to shear the LM (LLPF), and rump fat measured at the sacro-iliac crest in the chiller (CHILLP8) were identified using a set of 53,798 SNP genotyped on 940 taurine and indicine cattle sampled from a large progeny test experiment. Of these SNP, 87, 64, and 63 were significantly (P G SNP, was used to confirm these locations. In total, 37 SNP were significantly (P < 0.05) associated with the same trait and with the same favorable homozygote in both data sets, representing 27 chromosomal regions. For the trait IMF, the effect of SNP in the confirmation data set was predicted from the discovery set by multiplying the estimated allele effect of each SNP in the discovery set by the number of copies of the reference allele of each SNP in the confirmation set. These weighted effects were then summed over all SNP to generate a molecular breeding value (MBV) for each animal in the confirmation data set. Using a bivariate analysis of MBV and IMF phenotypes of animals in the confirmation set, a panel of 14 SNP explained 5.6 and 15.6% of the phenotypic and genetic variance of IMF, respectively, in the confirmation data set. The amount of variation did not increase as more SNP were added to the MBV and instead decreased to 1.2 and 3.8% of the phenotypic and genetic variance of IMF, respectively, when 329 SNP were included in the analysis.

Neonatal piglet traits of importance for survival in crates and indoor pens

Abstract: The primary aim of the present study was to investigate whether the same piglet traits contributed to the same causes of neonatal piglet mortality in crates (CT) and pens (PN). Gilts originating from 2 distinct genetic groups that differed in breeding value for piglet survival rate at d 5 (SR5) were used. These were distributed to farrow in either PN or CT as follows: high-SR5 and CT (n = 30); low-SR5 and CT (n = 27); high-SR5 and PN (n = 22); and low-SR5 and PN (n = 24). Data on individual piglets were collected at birth, including interbirth interval; birth order; birth weight; rectal temperature at birth, 2 h after birth, and 24 h after birth; cordal plasma lactate; and latency to first suckle. Based on autopsy, causes of mortality were divided into stillborn, bitten to death, starvation, crushed, disease, and other causes. Potential risk factors of dying were estimated using a GLM with a logit link function. No significant effect (NS) of housing was observed on the odds of a piglet being stillborn (F(1,73) = 0.1, NS), being crushed (F(1,53) = 1.4, NS), or dying of starvation (F(1,53) = 0.3, NS). No significant differences were observed between the 2 genetic groups for any category of mortality. Piglet traits for pre- and postnatal survival were the same for CT and PN. The odds of being stillborn were increased in piglets born late in the birth order (F(1,1061) = 33.5, P < 0.0001), after a long interbirth interval (F(1,1061) = 19.2, P < 0.0001), and with a lighter birth weight (F(1,1061) = 9.2, P = 0.003). The lighter the birth weight of the piglets, the greater were the odds of being crushed (F(1,1050) = 18, P < 0.0001) and dying of starvation (F(1,1050) = 19, P < 0.0001). The lower the rectal temperature 2 h after birth, the greater were the odds of being crushed (F(1,1050) = 4.6, P = 0.03), starving (F(1,1050) = 16.6, P < 0.0001), or dying of diseases (F(1,1050) = 4.9, P = 0.03). Increased cordal plasma lactate increased the odds of dying from starvation (F(1,1050) = 18, P < 0.0001). In both CT and PN, the birth weight, body temperature 2 h after birth, and birth process were important traits related to crushing, starvation, and disease. Neither housing nor breeding value influenced mortality or traits of importance for the inborn viability of piglets. The results emphasize that the microclimate in the PN for newborn piglets and its heat-preserving properties are more important for survival than whether the sow is crated or penned.

Long-term defaunation increases the abundance of cellulolytic ruminococci and methanogens but does not affect the bacterial and methanogen diversity in the rumen of sheep

Abstract: Protozoa are commensal eukaryotes in the rumen of herbivores. Protozoa are large producers of hydrogen, which is utilized by methanogenic archaea to produce methane, a greenhouse gas. The removal of protozoa from the rumen (defaunation) decreases methanogenesis, but also negatively affects fiber digestion, which is the main function of the rumen. The aim of this study was to examine the effect of long-term defaunation on the structure of the microbiota and particularly methanogenic archaea and fibrolytic bacteria to better understand the microbial mechanisms responsible for the decrease in methanogenesis and fibrolysis. The trial was conducted in 5 adult sheep subjected successively to long-term defaunation (2 yr), refaunation (12 wk), and short-term defaunation (10 wk). Methanogens were enumerated by quantitative PCR targeting the rrs (16S ribosomal RNA subunit) and mcrA (methyl coenzyme-M reductase) genes. The rrs gene was used to quantify the 3 major culturable rumen cellulolytic bacterial species (i.e., Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens) and total bacteria. Bacterial and methanogen diversity was also examined by PCR-DGGE (PCR-denaturing gradient gel electrophoresis) analysis targeting the rrs and mcrA genes, respectively. Total rumen bacterial density estimated as rrs copies per gram of DM of rumen content increased in response to long- and short-term defaunation (+1 log, P < 0.001), but without noticeable shifts in diversity. Defaunation increased the rrs copies per gram of DM of rumen content of R. albus and R. flavefaciens (+2 log, P < 0 0.001), but did not affect that of F. succinogenes. Despite a 20% reduction in methane emission in the 2 defaunated periods, the mcrA and rrs copies of methanogens per gram of DM of rumen content increased (+1 log, P < 0.001) in the absence of protozoa, whereas the diversity of the dominant methanogenic community was not modified. This study shows no major difference between long- and short-term defaunation in abundance and diversity of bacteria and archaea. It also provides evidence that monitoring the abundance and diversity of methanogens is not sufficient to comprehend the microbial mechanisms leading to a reduction in methane emissions by ruminants. This study also reports for the first time in sheep a selective effect of defaunation on the abundance of cellulolytic bacterial species.

Extent of linkage disequilibrium and effective population size in Finnish Landrace and Finnish Yorkshire pig breeds.

Abstract: The extent of linkage disequilibrium (LD) and effective population size in Finnish Landrace and Finnish Yorkshire pig populations were studied using a whole genome SNP panel (Illumina PorcineSNP60 BeadChip) and pedigree data. Genotypic data included 86 Finnish Landrace and 32 Finnish Yorkshire boars. Pedigree data included 608,138 Finnish Landrace 554,237 and Finnish Yorkshire pigs, and on average 15 ancestral generations were known for the reference animals, born in 2005 to 2009. The breeding animals of the 2 populations have been kept separate in the breeding programs. Based on the pedigree data, the current effective population size for Finnish Landrace is 91 and for Finnish Yorkshire 61. Linkage disequilibrium measures (D' and r(2)) were estimated for over 1.5 million pairs of SNP. Average r(2) for SNP 30 kb apart was 0.47 and 0.49 and for SNP 5 Mb apart 0.09 and 0.12 for Finnish Landrace and Finnish Yorkshire, respectively. Average LD (r(2)) between adjacent SNP in the Illumina PorcineSNP60 BeadChip was 0.43 (57% of the adjacent SNP pairs had r(2) > 0.2) for Finnish Landrace and 0.46 (60% of the adjacent SNP pairs had r(2) > 0.2) for Finnish Yorkshire, and average r(2) > 0.2 extended to 1.0 and 1.5 Mb for Finnish Landrace and Finnish Yorkshire, respectively. Effective population size estimates based on the decay of r(2) with distance were similar to those based on the pedigree data: 80 and 55 for Finnish Landrace and Finnish Yorkshire, respectively. Thus, the results indicate that the effective population size of Finnish Yorkshire is smaller than of Finnish Landrace and has a clear effect on the extent of LD. The current effective population size of both breeds is above the recommended minimum of 50 but may get smaller than that in the near future, if no action is taken to balance the inbreeding rate and selection response. Because a moderate level of LD extends over a long distance, selection based on whole genome SNP markers (genomic selection) is expected to be efficient for both breeds.

Feed efficiency differences and reranking in beef steers fed grower and finisher diets

Abstract: This 3-yr study used 490 steers to determine whether feedlot steers changed their feed efficiency (FE) ranking when fed a grower diet, then a finisher diet. The steers were crossbreds and were between 5 to 7 mo of age. There were 2 feeding periods each year. Within each year, approximately 90 steers had their diet switched from a grower to a finisher diet (feed-swap group), whereas another 90 steers were fed either the grower (grower-fed group) or the finisher (finisher-fed group) diet throughout the feeding trial. Each feeding test lasted for a minimum of 10 wk, and all steers were fed ad libitum. Individual animal feed intakes were collected using the GrowSafe feeding system, and BW were measured every 2 wk. Residual feed intake (RFI), G:F, and Kleiber ratio (KR) were computed at the end of each feeding period. For each measure of efficiency, animals were classified as low, medium, or high based on 0.5 SD from the mean. The majority of steers did not maintain the previous efficiency class in the second period. Approximately 58, 51, and 51% of steers in the feed-swap group, finisher-fed group, and the grower-fed group, respectively, changed their RFI measure by 0.5 SD. A low rank correlation occurred in all test groups but was less in the feed-swap group. Spearman rank correlations between the 2 feeding periods in the feed-swap group were 0.33, 0.20, and 0.31 for RFI, G:F, and KR, respectively. Classifications based on G:F and KR showed that a greater number of steers (P 0.05) between the proportions of individuals that changed or maintained their FE class. In the groups without a feed-swap, there was no difference (P > 0.05) in the proportion of steers that changed or maintained the same FE class for all FE measures. Our results suggest that diet type and feeding period affect the FE ranking in beef steers. A feedlot diet is ideal for evaluating the FE potential of steers for feedlot profitability; however, we suggest that tests involving less dense diets should be examined in an effort to understand the relationships between FE and feeder profitability.

Effects of bovine fatty acid synthase, stearoyl-coenzyme A desaturase, sterol regulatory element-binding protein 1, and growth hormone gene polymorphisms on fatty acid composition and carcass traits in Japanese Black cattle.

Abstract: The quality of fat is an important factor in defining the quality of meat. Fat quality is determined by the composition of fatty acids. Among lipid metabolism-related genes, including fatty acid synthesis genes, several genetic variations have been reported in the bovine fatty acid synthase (FASN), stearoyl-CoA desaturase (SCD), sterol regulatory element-binding protein 1 (SREBP1), and GH genes. In the present study, we evaluated the single and epistatic effects of 5 genetic variations (4 SNP and 1 insertion/deletion) in 4 genes (FASN, SCD, SREBP1, and GH) on the fatty acid composition of the longissimus thoracis muscle and carcass and meat quality traits in 480 commercial Japanese Black cattle. Significant single effects of FASN, SCD, and GH(L127V) polymorphisms on the fatty acid composition of the longissimus thoracis muscle were detected. The A293V polymorphism of SCD had the largest effect on myristic acid (C14:0, P 0.1) were detected between FASN and SCD for any carcass trait. When the genotypes of 3 markers (FASN, SCD, and GH(L127V)) were substituted from the lesser effect allele to the greater effect allele, the proportion of C18:1 increased by 4.46%. More than 20% of the genetic variance in the C18:1 level could be accounted for by these 3 genetic markers. The present results revealed that polymorphisms in 2 fatty acid synthesis genes (FASN and SCD) independently influenced fatty acid composition in the longissimus thoracis muscle. These results suggest that SNP in the FASN and SCD genes are useful markers for the improvement of fatty acid composition in commercial Japanese Black cattle.

Farm factors associated with the use of antibiotics in pig production.

Abstract: The aim of this study was to investigate farm-level economic and technical factors that are associated with the use of antibiotics on pig farms. Identification of such factors, like farm size and net farm result, may help to increase epidemiological knowledge and to specify farm advice and policy making to reduce inappropriate use of antibiotics. The study used over 300 farm-year records collected during 2004 to 2007 from pig farms in the Netherlands. Data included economic and technical factors as well as antibiotic administration. Data were statistically analyzed for factors associated with antibiotic use, both for fattening pig and sow farms (piglets only), separately. The response variable was the average number of daily dosages per average pig year. Statistical analysis was performed on 16 and 19 potential explanatory factors for the fattening pig and sow farms, respectively. The results showed that, both on the fattening pig and sow farms, the average use of antibiotics increased from 2004 to 2006, but decreased during 2007, but the effect of year was not significant (P > 0.05). Use of antibiotics varied between individual farms. Large farm repeatability for the use of antibiotics in the different years was found. Factors associated (P 0.05) related to the on-farm use of antibiotics. Therefore, it is recommended to focus future research on the potential role of socioeconomic factors associated with antibiotic use on pig farms.

Genome-wide marker-assisted selection combining all pedigree phenotypic information with genotypic data in one step: An example using broiler chickens.

Abstract: Data of broiler chickens for 2 pure lines across 3 generations were used for genomic evaluation. A complete population (full data set; FDS) consisted of 183,784 and 164,246 broilers for the 2 lines. The genotyped subsets (SUB) consisted of 3,284 and 3,098 broilers with 57,636 SNP. Genotyped animals were preselected based on more than 20 traits with different index applied to each line. Three traits were analyzed: BW at 6 wk (BW6), ultrasound measurement of breast meat (BM), and leg score (LS) coded 1 = no and 2 = yes for leg defect. Some phenotypes were missing for BM. The training population consisted of the first 2 generations including all animals in FDS or only genotyped animals in SUB. The validation data set contained only genotyped animals in the third generation. Genetic evaluations were performed using 3 approaches: 1) phenotypic BLUP, 2) extending BLUP methodologies to utilize pedigree and genomic information in a single step (ssGBLUP), and 3) Bayes A. Whereas BLUP and ssGBLUP utilized all phenotypic data, Bayes A could use only those of the genotyped subset. Heritabilities were 0.17 to 0.20 for BW6, 0.30 to 0.35 for BM, and 0.09 to 0.11 for LS. The average accuracies of the validation population with BLUP for BW6, BM, and LS were 0.46, 0.30, and <0 with SUB and 0.51, 0.34, and 0.28 with FDS. With ssGBLUP, those accuracies were 0.60, 0.34, and 0.06 with SUB and 0.61, 0.40, and 0.37 with FDS, respectively. With Bayes A, the accuracies were 0.60, 0.36, and 0.09 with SUB. With SUB, Bayes A and ssGBLUP had similar accuracies. For traits of high heritability, the accuracy of Bayes A/SUB and ssGBLUP/FDS were similar, and up to 50% better than BLUP/FDS. However, with low heritability, ssGBLUP/FDS was 4 to 6 times more accurate than Bayes A/SUB and 50% better than BLUP/FDS. An optimal genomic evaluation would be multi-trait and involve all traits and records on which selection is based.

Muscle characteristics and meat quality traits are affected by divergent selection on residual feed intake in pigs.

Abstract: Residual feed intake (RFI) is defined as the difference between the observed feed intake and that expected based on requirements for maintenance and production. A divergent selection was conducted during 4 generations in Large White male pigs to produce low and high RFI lines. The present study aims at determining the influence of this selection on biochemical and histological traits of skeletal muscle, and relating these changes to correlated effects on growth, carcass composition, and meat quality traits. At 8 d preslaughter, biopsies from the LM were taken in the fed state on 14 females from each RFI line fed ad libitum. Animals were slaughtered at 107.8 ± 8.0 kg of BW without any previous fasting. Samples of LM, semimembranosus (SM), biceps femoris (BFM), and rhomboideus muscles were taken at both 30 min and 24 h postmortem. Myofiber typing was only assessed in LM. Low RFI pigs ("efficient") had leaner carcasses with greater muscle content (P 0.10) between lines was found for citrate synthase and lactate dehydrogenase activities, mitochondrial activity, and expression of genes coding for uncoupling proteins 2 and 3. Differences between RFI pigs in plasma leptin, cortisol, and thyroid hormone concentrations are presented and discussed. In conclusion, selection for low RFI influenced muscle properties in a way favoring muscle mass, but likely impairing meat quality.

Effects of chronic exposure of diets with reduced concentrations of aflatoxin and deoxynivalenol on growth and immune status of pigs.

Abstract: This study investigated the growth and immune responses of pigs fed diets containing reduced concentrations of aflatoxin (AF) and deoxynivalenol (DON) from naturally contaminated corn. Sixty gilts (13.9 ± 0.2 kg of BW) were randomly assigned to 4 treatments (5 replicate pens per treatment and 3 pigs per pen): A (a control diet without detectable AF and DON); B (a diet with 60 μg of AF/kg and 300 μg of DON/kg); C (a diet with 120 μg of AF/kg and 600 μg of DON/kg); and D (a diet with 180 μg of AF/kg and 900 μg of DON/kg). Pigs were allowed ad libitum access to feed and water for 33 d. Feed intake and BW were measured weekly and pigs were bled (8 mL) on d 33 to measure the numbers of blood cells, to conduct liver function tests, and to measure immunological variables including IgG, IgM, interferon γ, IL4, IL6, and tumor necrosis factor α. One pig representing the average BW of each pen was killed to obtain the liver, kidneys, and spleen for weight, tissue color measurement, and histological evaluation of tissue damage. When compared with A, pigs in C and D tended to have reduced ADG (0.52 vs. 0.43 and 0.41 kg/d, respectively; P = 0.058) and ADFI (1.04 vs. 0.92 and 0.88 kg/d, respectively; P = 0.061). White blood cell count of pigs in D (23.4 × 10(3) cells/μL) was greater (P < 0.05) than those in A, B, and C (18.4, 18.5, and 16.8 × 10(3) cells/μL, respectively. Serum tumor necrosis factor α concentration of pigs in D (335 pg/mL) differed (P < 0.05) from those in A and C (299 and 290 pg/mL, respectively). Pigs in B and D had greater (P < 0.05) fibrosis in liver tissues than those in A. Collectively, this study shows that diets containing both AF and DON greater than 60 and 300 μg/kg, respectively, may reduce growth and decrease feed intake, whereas diets containing 120 μg of AF/kg and 600 μg of DON/kg may result in altered immune health, systemic inflammation, and partial liver damage, causing further reduction in growth of pigs.

Increased dietary zinc oxide changes the bacterial core and enterobacterial composition in the ileum of piglets.

Abstract: This study was conducted to investigate the effects of increased dietary ZnO on the bacterial core and enterobacterial composition in the small intestine of piglets that were fed diets containing a total of 124 or 3,042 mg of Zn per kilogram of diet, respectively. Zinc was supplemented to the basal diet as ZnO. Bacterial 16S rRNA genes of ileal DNA extracts were PCR-amplified with 2 bar-coded primer sets and sequenced by 454 pyrosequencing. The bacterial core species were calculated from the relative abundances of reads present in 5 of 6 samples per group and at a minimum of 5 sequences per sample. The reference database SILVA was used to assign sequence reads at an alignment minimum of 200 bases and 100% identity. Lactic acid bacteria dominated the bacterial core, but showed diverse responses to dietary ZnO. Of the dominant Lactobacillus spp., Lactobacillus reuteri was reduced due to increased dietary ZnO (44.7 vs. 17.9%; P=0.042), but L. amylovorus was not influenced. However, the changes of relative abundances of other lactic acid bacteria were more noteworthy; Weissella cibaria (10.7 vs. 23.0%; P=0.006), W. confusa (10.0 vs. 22.4%; P=0.037), Leuconostoc citreum (6.5 vs. 14.8%; P=0.009), Streptococcus equinus (0.14 vs. 1.0%; P=0.044), and S. lutetiensis (0.01 vs. 0.11%; P=0.016) increased in relative abundance. Nonlactic acid bacteria that were influenced by increased dietary ZnO included the strict anaerobic species, Sarcina ventriculi, which showed a strong numerical decrease in relative abundance (14.6 vs. 5.1%). Species of the Enterobacteriaceae increased their relative abundance, as well as species diversity, in the high dietary ZnO experimental group. Bacterial diversity indices were increased due to increased dietary ZnO (P < 0.05), which was traced back to the increase of sequences from subdominant species. Increased dietary ZnO led to an increase of less prominent species and, thus, had a major impact on the bacterial composition and diversity in piglets. This effect may help to stabilize the intestinal microbiota in the sensitive postweaning period.

Endogenous fraction and urinary recovery of purine derivatives obtained by different methods in Nellore cattle.

Abstract: Two experiments were conducted to assess the endogenous fraction of purine derivative (PD) excretion, urinary recovery, and intestinal digestibility of purines in Nellore heifers. For both experiments, 8 Nellore heifers fitted with ruminal and abomasal cannulas were allocated to two 4 × 4 Latin squares. The diets were based on corn silage and concentrate (60 and 40% DM basis, respectively); feces and urine samples were obtained by total collection, and abomasal DM flow was estimated using indigestible NDF as an internal marker. In Exp. I, 4 of the 8 heifers (BW 258 ± 20 kg) were also fitted with ileal cannula. The planned treatments were 4 different DMI: 1.2, 1.6, 2.0, and 2.4% of BW (DM basis). The endogenous losses and purine recovery as urinary PD were estimated using linear regression between daily urinary PD excretion (Y) and daily abomasal flow of purine bases (X), expressed in millimoles per kilogram of BW(0.75). In Exp. II, the same 8 Nellore heifers (BW of 296 ± 15 kg) were fed at 1.37% BW (DM basis). The treatments were the infusion of purines (RNA from torula yeast, type VI, Sigma) into the abomasum in increasing amounts (0, 33, 66, and 100 mmol/d). All statistical analyses were performed using the PROC MIXED procedure in SAS. In Exp. I, the DMI range was 1.16 to 1.84% of BW and did not affect (P > 0.05) the apparent RNA digestibility in the small intestine, which had a mean of 75.6%, and a true digestibility of 93.0%. The mean ratio of the N-RNA to the total-N in the ruminal bacteria was 0.137. The daily urinary PD excretion (Y, mmol/kg of BW(0.75)) was a function of RNA flow in the abomasum (X, mmol/kg of BW(0.75)): Y = 0.860X + 0.460, where 0.860 and 0.460 were the PD recovery of purines and the endogenous fraction (in mmol/kg of BW(0.75)), respectively. In Exp. II, the daily urinary PD excretion was a function of RNA flow in the abomasum: Y = 0.741X + 0.301, where 0.741 and 0.301 were the recovery of PD in urine of infused purines and the endogenous losses (in mmol/kg of BW(0.75)), respectively. In conclusion, our data suggest that in Nellore heifers the respective values of endogenous PD excretion (mmol/kg of BW(0.75)), urinary recovery of the purines absorbed in the abomasum, and true digestibility of RNA in the small intestine were 0.30, 0.80, and 0.93.

Effects of polymorphisms in the calpastatin and μ-calpain genes on meat tenderness in 3 French beef breeds.

Abstract: The objectives of the study were to evaluate allelic frequencies and to test the association of polymorphisms in the calpastatin (CAST) and μ-calpain (CAPN1) genes with meat tenderness in 3 French beef breeds A total of 1,114 Charolais, 1,254 Limousin, and 981 Blonde d'Aquitaine purebred young bulls were genotyped for 3 SNP in the CAST gene and 4 SNP in the CAPN1 gene Two of these markers, 1 in each gene, can be found in Australian or American commercial genetic tests Others have previously been reported in American studies or are newly evidenced SNP The quantitative traits studied were Warner-Bratzler shear force and a tenderness score evaluated by trained sensory panels All the SNP were informative in the 3 breeds Associations of individual markers or haplotypes with traits were analyzed The results differed in the 3 breeds The G allele of a CAST marker (position 97574679 on Btau40) was found to exert a significant effect on the shear force (+018 phenotypic SD; RSD) and tenderness score (-022 RSD) in the Blonde d'Aquitaine breed In the same breed, this marker was associated with another CAST SNP (position 97576054 on Btau40) such that the GA haplotype appeared to be associated with tougher meat Two CAPN1 markers (positions 45221250 and 45241089 on Btau40) had a significant effect on both traits in the Charolais breed (from |011| to |025| RSD) In the same breed, these markers were associated with another CAPNI SNP (position 45219395 on Btau40) such that the ACA and AGG haplotypes appeared to be associated with a tender meat and a tougher meat, respectively Consequently, the present results indicate that the effects of the markers studied are breed-specific and cannot be extended to all Bos taurus breeds Further studies are also required to identify other more appropriate markers for French beef breeds

Effect of different genomic relationship matrices on accuracy and scale

Abstract: Phenotypic data on BW and breast meat area were available on up to 287,614 broilers. A total of 4,113 birds were genotyped for 57,636 SNP. Data were analyzed by a single-step genomic BLUP (ssGBLUP), which accounts for all phenotypic, pedi- gree, and genomic information. The genomic relation- ship matrix (G) in ssGBLUP was constructed using either equal (0.5; GEq) or current (GC) allele frequen- cies, and with all SNP or with SNP with minor allele frequencies (MAF) below multiple thresholds (0.1, 0.2, 0.3, and 0.4) ignored. Additionally, a pedigree-based relationship matrix for genotyped birds (A 22) was avail- able. The matrices and their inverses were compared with regard to average diagonal (AvgD) and off-diag- onal (AvgOff) elements. In A 22, AvgD was 1.004 and AvgOff was 0.014. In GEq, both averages decreased with the increasing thresholds for MAF, with AvgD decreasing from 1.373 to 1.020 and AvgOff decreasing from 0.722 to 0.025. In GC, AvgD was approximately 1.01 and AvgOff was 0 for all MAF. For inverses of the relationship matrices, all AvgOff were close to 0; AvgD was 2.375 in A22, varied from 11.563 to 12.943 for GEq, and increased from 8.675 to 12.859 for GC as the threshold for MAF increased. Predictive ability with all GEq and GC was similar except that at MAF = 0.4, they declined by 0.01 for BW and improved by 0.01 for breast meat area. Compared with BLUP, EBV in the ssGBLUP were, on average, increased by up to 1 additive SD greater with GEq and decreased by 2 additive SD less with GC. Genotyped animals were bi- ased upward with GEq and downward with GC. The biases and differences in EBV could be controlled by adding a constant to GC; they were eliminated with a constant of 0.014, which corresponds to AvgOff in A22. Unbiased evaluation in the ssGBLUP may be obtained with GC scaled to be compatible with A. The reduc- tion of SNP with small MAF has a small effect on the real accuracy, but it may falsely increase the estimated accuracies by inversion.

Grass silage intake, rumen and blood variables, ultrasonic and body measurements, feeding behavior, and activity in pregnant beef heifers differing in phenotypic residual feed intake

Abstract: The objectives of this study were to quantify the phenotypic variation in residual feed intake (RFI) in pregnant beef heifers offered a grass silage diet and to characterize their productivity. Seventy-three pregnant (mean gestation d 198, SD = 27 d) Simmental and Simmental × Holstein-Friesian heifers (mean initial BW 548, SD = 47.5 kg) were offered grass silage ad libitum. Heifer DMI, BW, BCS, skeletal measurements, ultrasonic fat and muscle depth, visual muscularity score, rumen fermentation, total tract digestibility, blood metabolite and hematology variables, feeding, and activity behavior were measured during an 84-d feed intake study. After parturition calf birth weight, calving difficulty, cow serum IgG, hematology variables, and calf humoral immune status were measured. In a subset of cows (n = 28), DMI, milk yield and various body composition variables were also measured approximately 3 wk postpartum. Phenotypic RFI was calculated for each animal as the difference between actual DMI and expected DMI. Expected DMI was computed for each animal by regressing average daily DMI on conceptus-adjusted mean BW(0.75) and conceptus-adjusted ADG over an 84-d period. Within breed, heifers were ranked by RFI into low (efficient), medium, and high (inefficient) groups by dividing them into thirds. Heifers with high RFI had 8.8 and 17.1% greater (P 0.05). Residual feed intake was positively correlated with DMI (r = 0.85) but not with feed conversion ratio, ADG, or BW. The RFI groups did not differ (P > 0.05) in skeletal size, BCS, ultrasonic fat depth, total tract digestibility, calf birth weight, calving difficulty, serum IgG concentrations, or milk yield. Visual muscularity scores, initial test and postpartum ultrasonic muscle depth were negatively correlated with RFI (P < 0.05). Including mean ultrasonic muscle depth into the base RFI regression model increased its R(2) (0.29 to 0.38). Pearson rank correlation between RFI and muscle-adjusted RFI was 0.93. The results show that efficient RFI heifers consumed less feed without any compromise in growth, body composition, or maternal traits measured.

Concentration of dietary calcium supplied by calcium carbonate does not affect the apparent total tract digestibility of calcium, but decreases digestibility of phosphorus by growing pigs

Abstract: A regional experiment was conducted to test the hypothesis that the concentration of dietary Ca does not affect the digestibility of Ca or P in diets fed to growing pigs. Six diets based on corn, potato protein isolate, cornstarch, and soybean oil were for- mulated. All diets also contained monosodium phos- phate, crystalline AA, salt, and a vitamin-micromineral premix. The only difference among the diets was that varying concentrations of calcium carbonate were used to create diets containing 0.33, 0.46, 0.51, 0.67, 0.92, and 1.04% Ca. All diets contained between 0.40 and 0.43% P. Six universities participated in the experi- ment and each university contributed 2 replicates to the experiment for a total of 12 replicates (initial BW: 23.1 ± 4.4 kg). Pigs were placed in metabolism cages that allowed total, but separate, collection of feces and urine from the pigs. Pigs within each replicate were randomly allotted to the 6 diets and fed experimental diets for 14 d with urine and feces being collected over a 5-d period. Diets, feces, and urine samples were ana- lyzed for Ca and P, and the daily balance, the appar- ent total tract digestibility (ATTD), and the retention of Ca and P were calculated. Results indicated that intake, fecal excretion, and urinary excretion of Ca in- creased (linear, P < 0.05) as dietary Ca concentration increased. The daily intake of P was not affected by the dietary concentration of Ca, but fecal excretion of P increased (linear, P < 0.05) as dietary Ca concen- trations increased. In contrast, urinary P output was decreased (linear, P < 0.05) as dietary Ca increased. The retention of Ca increased (linear, P < 0.05) from 1.73 to 4.60 g/d, whereas the retention of P decreased (linear, P < 0.05) from 1.98 to 1.77 g/d as dietary Ca concentrations increased. However, if calculated as a percentage of intake, both Ca and P retention were decreased (linear, P < 0.05) as dietary Ca concentra- tion increased (from 55.4 to 46.1% and from 48.4 to 43.5%, respectively). The ATTD of Ca was not affected by the dietary concentration of Ca, but the ATTD of P was decreased (linear, P < 0.05) from 56.9 to 46.2% as dietary Ca concentration increased. It is concluded that the dietary concentration of Ca does not affect the ATTD of Ca in calcium carbonate, but increased concentrations of dietary Ca may decrease the ATTD of P in diets based on corn, potato protein isolate, and monosodium phosphate.