Showing papers in "Canadian Journal of Animal Science in 2003"
TL;DR: Crossbred steers from the five BeefBooster strains were used to determine the relationships between residual feed intake and growth rate, body composition and heat production, and to quantify differences in RFI independent of differences in body composition.
Abstract: Crossbred steers (n = 176), 7–8 mo of age and from the five BeefBooster strains (M1, M2, M3, M4 and TX), were used to determine the relationships between residual feed intake (RFI) and growth rate, body composition and heat production (HP), and to quantify differences in RFI independent of differences in body composition Animals with different RFI levels were also characterized for growth, carcass and body compositional traits Steers from each genetic strain were selected at random and serially slaughtered on 5 pre-selected days of the finishing period Steers grew at 152 (SD = 022) kg d-1 and had dry matter intake (DMI) of 85 (SD = 10) kg d-1 during the last 71 to 183 d before slaughter Metabolic mid-point weight, average daily gain (ADG), gain in empty body fat and gain in empty body water accounted for 679, 86, 39 and 11%, respectively, of the variation in actual feed intake Similarly, metabolic mid-point weight (685%), ADG (82%), gain in ultrasound backfat thickness (18%), gain in ultra
457 citations
TL;DR: Forages represent a high proportion of ruminant diets they provide a significant quantity of fatty acids (FA), and effects of growth stage, fertilization, conservation method, growth period, species, and cultivar on forage FA were determined.
Abstract: When forages represent a high proportion of ruminant diets they provide a significant quantity of fatty acids (FA). Effects of growth stage, fertilization, conservation method, growth period, species, and cultivar on forage FA were determined in four experiments. Concentrations of C16:0, C18:2, C18:3, and total FA (TFA) in timothy (Phleum pratense L.) decreased (P < 0.01), respectively, by 15, 16, 31, and 23% between stem elongation and early flowering. Nitrogen fertilization (120 vs. 0 kg N ha-1) caused an increase (P < 0.01) of 18% of C16:0, 12% of C18:2, 40% of C18:3, and 26% of TFA concentrations. Phosphorus was not deficient and P fertilization (45 vs. 0 kg P ha-1) had no significant effect on timothy FA concentrations. Wilting and drying decreased (P < 0.01) timothy C18:2, C18:3, and TFA concentrations. Concentrations of C18:2, C18:3, and TFA were higher in summer regrowth than in spring growth, primarily in orchardgrass (Dactylis glomerata L.) and timothy (P < 0.01). Significant variation for all F...
238 citations
TL;DR: Lag regression analysis showed that previous daily udder temperatures together with environmental temperature parameters could successfully predict currentUdder temperature with a high degree of accuracy.
Abstract: The daily and within-day variation in udder temperature was monitored in dairy cows (n = 10) using infrared thermography (IRT). The initial assessment and prediction of udder surface temperature va...
162 citations
TL;DR: In this article, the level and digestibility of amino acids and the level of glucosinolates in toasted and non-toasted canola meal samples were analyzed for apparent ileal amino acid digestibilities using broiler chickens between 21 and 28 d of age.
Abstract: A study was conducted to determine the level and digestibilities of amino acids and the level of glucosinolates in toasted and non-toasted canola meal samples produced in commercial crushing plants in western Canada. A total of 26 non-toasted and 31 toasted canola meals samples were analyzed for apparent ileal amino acid digestibilities using broiler chickens between 21 and 28 d of age. Commercially toasted canola meal contained 5.6 g 16 g-1 N (range 5.3–5.9) of Lys with a digestibility ranging from 65.5 to 85.7% (mean = 78.0%). Non-toasted canola meal contained 6.0 g 16 g-1 N (range 5.7–6.3) Lys with digestibility values ranging from 87 to 92% (mean = 89.7%). Toasted canola meal had an average total digestible amino acid content (not including Tyr and Trp) of 69.6 g 16 g-1 N (range 56.6–75.6) while non-toasted canola meal had 77.6 g 16 g-1 N (range 73.1–82.0). The levels of aliphatic glucosinolates in the toasted (6.16 μmol g-1 meal, range 1.2–12.5) and non-toasted meals (10.5 μmol g-1 meal, range 7.8–15...
142 citations
TL;DR: The theory that sperm are prematurely activated by cryopreservation (“cryo-capacitation”) is described and strategies for preventing this damage are discussed.
Abstract: Artificial insemination has arguably been the most important practice contributing to the advancement of animal production. The numerous advantages of artificial insemination are augmented when the...
110 citations
TL;DR: In order to examine the relationship between herbage maturity and methane (CH4) emission under conditions which minimized opportunities for selective grazing, six 8-yr-old, dry and early-pregnant Charolais cows were grazed on a mono-specific pasture of timothy at four stages of maturity: early vegetative, heading, flowering, and senescence.
Abstract: In order to examine the relationship between herbage maturity and methane (CH4) emission under conditions which minimized opportunities for selective grazing, six 8-yr-old, dry and early-pregnant C...
105 citations
TL;DR: The results showed that: (1) the varieties had minimal effects on nutritional value; however, (2) stage of cutting had a large impact on chemical composition, protein and carbohydrate fractions, in vitro rumen degradability and energy value.
Abstract: The objective of this study was to investigate the effects of forage variety and stage of maturity on chemical composition, protein and carbohydrate subfractions, in vitro rumen degradability and energy content under the climatic conditions of western Canada. Two varieties of alfalfa (Medicago sativa L. cvs. Pioneer and Beaver) and timothy (Phleum pratense L. cvs. Climax and Joliette), grown at three locations in Saskatchewan (Canada), were cut at three stages [1 = 1 wk before commercial cut (early bud for alfalfa; joint for timothy); 2 = at commercial cut (late bud for alfalfa; pre-bloom head for timothy); and 3 = one week after commercial cut (early bloom for alfalfa; full head for timothy)]. The results showed that: (1) the varieties had minimal effects on nutritional value; however, (2) stage of cutting had a large impact on chemical composition, protein and carbohydrate fractions, in vitro rumen degradability and energy value. As plant maturity advanced from stage 1 to 3, the following changes were n...
84 citations
TL;DR: The fractional rates of extraction of total AA inflow to the liver are low and this allows short-term flexibility in the pattern of absorbed AA, which can result in lowered net conversion of plant protein to animal products.
Abstract: The dynamics of protein turnover confer great advantages for homeothermy, plasticity and metabolic function in mammals. The different roles played by the various organs have led to aspects of prote...
83 citations
TL;DR: The effects of environmental temperature on digestibility of diets should be taken into consideration when using the DE of the diet as determined from in vivo digestibility trials or calculated from chemical analyses in determining the DMI of feedlot cattle.
Abstract: and net energy of gain (NE g ) of the diet. These energy values were then used in CowBytes ® to predict dry matter intake (DMI), ADG, and days on feed (DOF) necessary to meet targeted quality grade of AA and weights of 522 and 568 kg for the heifers and steers, respectively. There was no effect of gender and prediction method interaction (P > 0.10) on any of the variables measured. There were no (P > 0.05) differences in predicted DMI by either the INVIVO or LAB method but both methods underestimated DMI actually consumed by the cattle by 6.8 and 4.9% (P = 0.007), respectively. Indeed, regression values from these predictive methods and actual DMI were (P < 0.05) different from the one-to-one relationship expected by definition. In spite of the higher actual DMI, the actual ADG of the cattle was 14 and 11% (P = 0.0004) lower than was predicted by either the INVIVO or LAB methods. A possible reason for the lower ADG could be an overestimation of DE of the diet. Thus, if available, users of CowBytes ® should use actual DMI from their experience in ration formulation. In addition, the effects of environmental temperature on digestibility of diets should be taken into consideration when using the DE of the diet as determined from in vivo digestibility trials or calculated from chemical analyses in determining the DMI of feedlot cattle.
83 citations
TL;DR: Reducing the percentage of highly fermentable concentrates in feedlot diets by increasing roughage level or limiting feed intake should decrease the incidence of these disorders, but this approach is usually not economically feasible.
Abstract: Digestive disorders account for approximately 25 to 33% of deaths in feedlot cattle and likely contribute to decreased performance and efficiency of production. A variety of nutritional, management...
72 citations
TL;DR: Diet provides the precursor fatty acids that are altered and deposited, and breed dictates, the amount of fat that is deposited in beef, and these fatty acids can be increased in beef by increasi...
Abstract: The diet is the source of many essential fatty acids such as linoleic and linolenic acids for all mammals. These fatty acids either, as altered isomers or as other elongated products, have been found to provide unique advantages to human health. Currently two conjugated linoleic acids (CLA) isomers (cis-9, trans-11 C18:2; trans-10, cis-12 C18:2) and two elongated products of linolenic acid [eicosapentaenoic acid (EPA, C20:5 n-3), docosahexaenoic acid (DHA, C22:6 n-3)] have been recognized for their roles in maintaining human health. Consumers can obtain these functional fatty acids from beef if the feeding management of beef cattle can be altered to include precursor fatty acids. Diet, breed, and gender are important factors that affect total fat content and/or the fatty acid profile of beef with regard to CLA, EPA, and DHA. Diet provides the precursor fatty acids that are altered and deposited, and breed dictates, the amount of fat that is deposited. These fatty acids can be increased in beef by increasi...
TL;DR: This paper proposes a methodology that it feels accounts for the requirements of accuracy, simplicity and safety of use, and a rationale for the standardization of the assays as a function of the conditions under which the tests are conducted.
Abstract: There is increasing interest in using enzymes that degrade plant cell walls in ruminant diets to enhance production efficiency. Despite strong evidence from several studies suggesting a beneficial effect of enzyme supplementation on nutrient utilization and animal performance, overall the results have been somewhat inconsistent. One of the main problems faced by researchers is the lack of adequate biochemical characterization of the products used, which leads to a poor understanding of their mode of action. Of these biochemical characteristics, enzyme activities are the most important, but they are not always evaluated prior to use. Furthermore, as many arbitrary units of expression for these activities coexist, direct comparisons among studies are essentially impossible. In this paper, we propose a methodology that we feel accounts for the requirements of accuracy, simplicity and safety of use. In addition, a rationale for the standardization of the assays as a function of the conditions under which the ...
TL;DR: In vitro ruminal biohydrogenation of linolenic and linoleic acids in timothy harvested from different growth stages, produced with or without fertilization, or conserved by different methods is compared.
Abstract: Polyunsaturated fatty acids from forages are hydrogenated in the rumen and this biohydrogenation depends on several factors. The objective of this study was to determine and compare in vitro ruminal biohydrogenation of linolenic (C18:3) and linoleic (C18:2) acids in timothy harvested from different growth stages, produced with or without fertilization, or conserved by different methods. In exp. 1, timothy was grown with (120 kg ha-1) and without N and harvested at four growth stages. In exp. 2, harvested timothy was conserved as fresh grass, wilted grass, dry hay, haylage, and silage, some with additives: haylage with lactic acid bateria (LAB), haylage with formic acid, silage with LAB, and silage with formic acid. Samples were incubated with rumen fluid in three trials to compare: (1) samples from exp. 1; (2) the five basic conserving methods of exp. 2, and; (3) how the silage additives affected biohydrogenation of C18:3 and C18:2. Effective disappearances and ruminal bypass of C18:3 and C18:2 were faste...
TL;DR: This work reports that pregnancy rates of 50% have been achieved routinely in well-managed heifers with sex-sorted, cryopreserved bovine sperm compared to 60–80% with unsexed control sperm.
Abstract: Development of flow cytometry for sorting mammalian sperm according to their sex chromosomes began in the late 1970s and early 1980s. This technology, which has recently been commercialized for bov...
TL;DR: Data from in vitro gas production from the diets indicated that oil inclusion reduced rate and lag time prior to initiation of gas production and that the increased CLA levels would improve meat shelf life.
Abstract: In the present study, we tested the hypothesis that feeding sunflower oil (SFO) containing about 70% linoleic acid would increase conjugated linoleic acids (CLA) content of beef and that the increased CLA levels would improve meat shelf life. Two feeding trials were conducted to determine the effect of SFO supplementation on beef production , carcass characteristics and meat quality parameters. In addition, the visual aspects of beef quality in retail display as influenced by dietary vitamin E were compared with that of the increased CLA derived from dietary SFO. In exp. 1, 72 finishing steers (465 ± 9 kg) were individually fed one of four dietary treatments: an unsupplemented control finishing diet, the control diet supplemented with 6% SFO, 500 IU head-1 d-1 vitamin E or a combination of 6% SFO and 500 IU head-1 d-1 vitamin E for 95 d. Data from in vitro gas production from the diets indicated that oil inclusion reduced rate and lag time prior to initiation of gas production. Dry matter intake (DMI) dec...
TL;DR: Results showed that all silages went through a rapid fermentation as indicated by rapid decline in pH and sharp increase in lactic acid concentration within the first 2 d of ensiling.
Abstract: The objective of this study was to determine the ensiling characteristics and ruminal nutrient degradabilities of faba bean (FS, Vicia faba L.), soybean (SS, Glycine max (L.) Merr.) and pea (PS, Pisum sativum L.) silages. Forages were harvested between the beginning- and full-seed stages and ensiled in mini-silos for 0, 2, 4, 16, and 45 d. Two lactating Holstein cows fitted with ruminal fistulae were used to determine ruminal nutrient degradabilities. Results showed that all silages went through a rapid fermentation as indicated by rapid decline in pH and sharp increase in lactic acid concentration within the first 2 d of ensiling. Extensive proteolysis took place between day 0 and day 4 post-ensiling as indicated by a significant reduction in true protein (TP) and a significant increase in non-protein nitrogen (NPN). During the 45 d of ensiling, TP decreased (P < 0.05) by 26, 31, and 45% while NPN increased (P < 0.05) by 82, 54, and 47% for FS, SS, and PS, respectively. Chemical analysis showed that the ...
TL;DR: It is suggested that the designation of a limiting amino acid is not appropriate for milk protein yield because it can be stimulated by any one of a number of amino acids.
Abstract: In this review, we discuss the mechanismsof responses of various tissues of the lactating dairy cow, particularly the mammary glands, to perturbations in supply of single amino acids that result in observed milk protein yields. Additions of methionine, lysine, histidine or leucine to the absorptive supply cause arterial concentrations of these amino acids to increase, mammary extractions to drop and mammary blood flow to decrease. Single subtractions of essential amino acids have the opposite effect. Changes in mammary blood flow that have been recorded can be explained as attempts by the mammary glands to restore intracellular ATP balance in the face of altered concentrations of energy metabolites in the general circulation. In a quantitative sense, milk protein yield is relatively insensitive to fluctuations in arterial amino acid concentrations but can be stimulated by any one of a number of amino acids. In this context, it is suggested that the designation of a limiting amino acid is not appropriate t...
TL;DR: The neural network model may be alternative method of predicting these traits and did not differ from the values estimated with the current Polish dairy cattle evaluation system.
Abstract: Milk yield predictions based on artificial neural etworks and multiple regression were studied. The 305-d lactation yield predictions were based on milk yield of the first 4 test days. Average 305-...
TL;DR: Bacterial protein meal produced from natural gas by Methylococcus capsulatus (Bath), Alcaligenes acidovorans, Bacillus brevis and Bacillus firmus was studied as a protein source for broiler chickens, finding the highest level of BPM significantly reduced growth, independent of protein level, whereas growth responses to lower levels of B PM were similar to the control diet.
Abstract: Bacterial protein meal (BPM) produced from natural gas by Methylococcus capsulatus (Bath), Alcaligenes acidovorans, Bacillus brevis and Bacillus firmus was studied as a protein source for broiler c...
TL;DR: A mink genomic library was screened with an (AC)15 oligonucleotide as the probe and six of the primer pairs revealed polymorphisms in American pine marten.
Abstract: A mink genomic library was screened with an (AC)15 oligonucleotide as the probe. Thirteen microsatellite loci were identified and primer sequences and amplification conditions were determined. All the 13 loci were polymorphic in black, brown, pastel and wild mink (n = 86), generating between 4 to 12 alleles per locus. Six of the primer pairs revealed polymorphisms in American pine marten. Key words: Mink, pine marten, microsatellite, polymorphism, polymerase chain reaction, primers
TL;DR: Improved knowledge of the causes of embryonic mortality and regulation of follicular growth and corpus luteum function should result in the development of improved, cost-effective hormonal regimes in cattle.
Abstract: Embryonic mortality in cattle is the death of the conceptus before Day 42 of pregnancy. Estimates of embryonic mortality varied greatly, ranging from 10 to 40% in first-service cattle to 65% in rep...
TL;DR: The metabolic disturbances that accompany an inflammatory challenge redirect nutrients from physiological processes important for growth and reproduction toward processes important in host defense, which requires increased provision of particular amino acids from the diet in order to spare body protein stores.
Abstract: The metabolic disturbances that accompany an inflammatory challenge redirect nutrients from physiological processes important for growth and reproduction toward processes important in host defense. These processes can require increased provision of particular amino acids from the diet in order to spare body protein stores. The pathways that are activated in response to inflammation have to be determined in order to quantify their specific amino acid requirements. For example, increased synthesis of acute phase proteins would require additional supply of specific amino acids according to their amino acid composition. Some dispensable amino acids can become limiting because their de novo synthesis could be impaired and/or be insufficient to cover the increased demands for synthesis of important metabolites. Moreover, amino acids can act on gene expression and as mediators or signal molecules and modulate numerous functions. However, the optimal conditions, especially concentration in physiological liquids, ...
TL;DR: Sixty individually housed Charolais crossbred steers originating from one ranch source had a 12-d adaptation period in their pens to adjust to their ration and surroundings, followed by two consecutive backgrounding periods with overall prevalence of C. andersoni and G. duodenalis 85 and 82%, respectively.
Abstract: Sixty individually housed Charolais crossbred steers originating from one ranch source had a 12-d (days 0–12) adaptation period in their pens to adjust to their ration and surroundings, followed by two consecutive backgrounding periods (85.5% roughage, 12% concentrate rations) with durations of 84 d (days 13–97) and 63 d (days 98–153), respectively. Steers had a 21-d adaptation period (days 154–174), followed by a 77-d (days 175–257) finishing period (20% roughage, 75% concentrate ration). Fecal samples and animal weights were collected from each steer every 28 d initially, then every 21 d during a test duration of 257 d. Feed weigh-backs were performed weekly for each steer. Fecal samples were processed, and Giardia duodenalis cysts and Cryptosporidium andersoni oocysts were counted. ADG, DMI and FE were calculated for each of the periods (Backgrounding Period 1, Backgrounding Period 2, Finishing Period 3 and Overall). Overall prevalence of C. andersoni and G. duodenalis was 85 and 82%, respectively. The...
TL;DR: In this paper, pigs were assigned to one of six dietary treatments comprised of a normal two-rowed, hulled variety of barley (CDC Bold) or three low-phytate genotypes selected to contain approximately 68, 41 or 3% of the normal level of phytate.
Abstract: Twenty-four crossbred barrows (Camborough 15 Line female × Canabred sire) weighing an average of 51.3 ± 5.1 kg were used in a trial conducted during two periods according to a completely randomized block design. The pigs were assigned to one of six dietary treatments comprised of a normal two-rowed, hulled variety of barley (CDC Bold) or three low-phytate genotypes selected to contain approximately 68, 41 or 3% of the normal level of phytate. A normal hulless barley (CDC Dawn) and a hulless genotype selected to contain 54% of the normal phytate content were also included. The diets fed contained 99.5% barley and 0.5% chromic oxide. The marked feed was provided for a 7-d acclimatization period, followed by a 3-d fecal collection. At the conclusion of the first replicate, the pigs were assigned to different treatments and the procedure was repeated resulting in eight observations per treatment. Selection for phytate content had no effects on the apparent fecal digestibility of dry matter, crude protein or g...
TL;DR: The superiority of Meishan sows During lactation is described in terms of its various components and the breed differences pertaining to sow metabolism and endocrinology during lactation are covered in order to provide an insight as to the possible mechanisms responsible for these superior performances.
Abstract: Meishan sows are known for their high prolificity and great lactational performances. Specific breed characteristics in terms of their embryonic, foetal and placental developments as well as their differences in mammary development at the end of gestation are covered. The various known metabolic, physiological and endocrine factors related to the decreased embryonic mortality and increased placental vascularity, which are largely responsible for the greater litter size of Meishans, are discussed. An overview of published data on the endocrine status of the sow and foetuses throughout pregnancy is also presented. The superiority of Meishan sows during lactation is described in terms of its various components (i.e., piglet growth and development, sow and litter behaviour, milk composition) and the breed differences pertaining to sow metabolism and endocrinology during lactation are covered in order to provide an insight as to the possible mechanisms responsible for these superior performances. This review i...
TL;DR: In this paper, the effects of feeding synthetic food-grade conjugated linoleic acid (CLA) containing 53% cis 9, trans 11 CLA and 44% trans 10, cis 12 CLA or bio-formed CLA as high CLA beef on adipose tissue development were investigated.
Abstract: Two rat feeding experiments were conducted, concurrently, for 48 d, to determine the effects of feeding synthetic food-grade conjugated linoleic acid (CLA) containing 53% cis 9, trans 11 CLA and 44% trans 10, cis 12 CLA or bio-formed CLA as high CLA beef on adipose tissue development. In exp. 1, 30 (10/diet) weaned male Wistar rats (51 ± 0.65 g) were fed, ad libitum, a control diet, control with sufficient added synthetic CLA to achieve CLA concentrations of 1.1% of diet DM or the control, where the soybean oil in the diet was replaced with sunflower oil. In exp. 2, 20 (10/diet) weaned male Wistar rats (52.5 ± 2.5 g) were fed, ad libitum, diets in which freeze dried beef replaced the casein as the protein source. The meat in the two diets was derived either from steers raised without dietary oil or from beef from steers fed oil to increase CLA content by 144% from 3.36 to 8.20 mg g-1 lipid (high CLA beef). At the end of the experiment the rats were humanely sacrificed and the organs, muscles and the retro...
TL;DR: This study was undertaken to verify if both grading methods predict similar lean yields and grading indexes in actual pork carcasses, and used data from four databases to do so.
Abstract: In Canada, actual grading methods based on Destron (DPG) and Hennessy (HGP) probe measurements were approved in 1994. This study was undertaken to verify if both grading methods predict similar lean yields and grading indexes in actual pork carcasses. Data from the following four databases were used, and included hot carcass weight, and backfat and muscle depths as measured by both probes: 1281 carcasses from the 1992 National Cutout, 495 and 76 carcasses from 1997 and 1998 Federation des Producteurs de Porc du Quebec studies respectively, and 266 from a 1999 Agriculture and Agri-Food Canada study. Probes were inserted alternatively at the Canadian grading site. Grading indexes were assigned from a 1999 official grid. For the four studied databases, the HGP-DPG lean yields were different from zero (P < 0.0001) with values of 0.33, 0.35, 0.36 and 0.18%, chronologically. The HGP-DPG grading indexes were also different from zero with values of 0.51 (P < 0.0001), 0.36 (P < 0.0001) and 0.50 (P < 0.0001), 0.21 ...
TL;DR: The effect of feeding corn-soybean meal-based diets with two levels of supplemental leucine on growth, carcass, and pork quality characteristics was evaluated in 40 individually fed finishing pigs.
Abstract: The effect of feeding corn-soybean meal-based diets with two levels of supplemental leucine (0 vs. 2%) on growth, carcass, and pork quality characteristics was evaluated in 40 individually fed fini...
TL;DR: A 14-d chick bioassay was conducted to estimate the relative bioavailability (RBV) of P in a low-phytate soybean meal (LPSBM) using slope-ratio techniques and a diet consisting of the basal diet plus supplemental methionine, lysine, threonine and tryptophan was also included to confirm that response to diets containing LPSBM was not due to the higher concentration of amino acids in those diets.
Abstract: A 14-d chick bioassay was conducted to estimate the relative bioavailability (RBV) of P in a low-phytate soybean meal (LPSBM) using slope-ratio techniques. A corn-soybean meal basal diet was formulated to supply total P and Ca at 3.3 and 10.5 g kg-1, respectively. Three reference diets were formulated by the addition of 0, 0.5 or 1.0 g kg-1 total P from monosodium phosphate (MSP). Four test diets were formulated by the addition of 0.5 or 1.0 g kg-1 total P from LPSBM or soybean meal (SBM). The additions of MSP, LPSBM, or SBM were made at the expense of corn starch. A diet consisting of the basal diet plus supplemental methionine, lysine, threonine and tryptophan was also included to confirm that response to diets containing LPSBM or SBM was not due to the higher concentration of amino acids in those diets. Each diet was randomly assigned to six replicate cages of four birds. Birds were fed from 1 to 3 wk of age. Body weight gain (P < 0.01) and feed intake (FI, P < 0.05) increased linearly as supplemental ...
TL;DR: The effects of feeding a linoleic acid-rich sunflower seed supplement and different levels of dietary protein on protozoal numbers and fermentation parameters in rumen fluid were determined in an 84-d experiment with rumen-cannulated sheep.
Abstract: The effects of feeding a linoleic acid-rich sunflower seed supplement and different levels of dietary protein on protozoal numbers and fermentation parameters in rumen fluid were determined in an 84-d experiment with rumen-cannulated sheep The experiment comprised four treatments, two with low crude protein diets [12% of dietary dry matter (DM)] and two with high protein diets (16% of DM) On both low and high protein diets, one treatment was without (Control) and one with the sunflower seed (high linoleic acid variety 6150) supplement (14% of dietary DM) The four diets used were based on corn silage and corn grain, and soybean meal was used to achieve the desired concentration of dietary protein The sheep were fully fed each morning and rumen fluid samples were taken 2 h later on various days of the experiment (daily during the first 14 d for enumeration of protozoa) In addition, rumen fluid was sampled at different hours after feeding on day 43 of the experiment Results showed a protozoa-decreasing