Undesirable side effects of selection for high production efficiency in farm animals: a review

Influence of varying protein and starch degradabilities on performance of lactating cows.

Polysaccharides entering the rumen can be considered as belonging to one of two general types: plant storage polysaccharides such as starch and the fructosans, or the structural polysaccharides which compose the greater part of all plant cell walls and which are loosely considered to form the fibrous component of animal feedstuffs. Additional, but limited, amounts of polymerized carbohydrate may also be ingested by the animal in the form of lower molecular weight oligosaccharides, as the sugar moiety of various glycoconjugates and as a component of animal and fish byproducts.

Polysaccharide degradation by rumen microorganisms

The effects of polysaccharides and tannins present in the hulls of field beans (Vicia faba L.) on the digestion of amino acids, starch and lipid were studied in poultry. A control diet without hulls and the same diet substituted with 400 g hulls/kg diet from three different varieties of beans were fed to 3-week-old chicks for 4 d. Digestibility coefficients for amino acids, starch and lipid were calculated from measurements made of these nutrients in the diets and the freeze-dried excreta with the aid of titanium dioxide as a marker. Activities of trypsin (EC 3.4.21.4), alpha-amylase (EC 3.2.1.1), and lipase (EC 3.1.1.3) in digesta removed from the upper jejunum, sucrase (EC 3.2.1.48) in the gut mucosa from the upper jejunum, and alpha-amylase and lipase in the pancreas were measured. The hulls were analysed for their polysaccharide and tannin contents. Results showed that the hulls were mostly carbohydrate in composition, with cellulose the predominant polysaccharide. Tannins present in the hulls of two coloured-flowering varieties (Brunette and Minica) were of the condensed type. The diet with tannin-free hulls (white-flowering variety Medes) lowered slightly the digestion of amino acids, starch and lipid compared with the control diet. This effect was believed to be due to inhibition of digestive enzymes, possibly through their adsorption onto the hulls. Diets with tannin-rich hulls (varieties Brunette and Minica) caused a large reduction in the digestion of amino acids, starch and lipid compared with the control diet mainly due to inactivation of digestive enzymes by the formation of tannin-enzyme complexes in the digestive tract. Enzyme activities could be partially restored by the addition of polyvinylpyrrolidone to the digesta. Tannins inactivated trypsin the most, alpha-amylase to a lesser extent and lipase the least and as a consequence lowered the digestion of amino acids the most, starch to a lesser extent and lipid the least. Tannins did not induce an increased pancreatic production of digestive enzymes, nor did they affect activity of jejunum mucosal sucrase. Condensed tannins from Brunette and Minica hulls were partially extractable in methanol alone, but required acidic methanol for fuller extraction. The vanillin:anthocyanidin ratio suggested that tannins were polymerized to the same degree in the Brunette and Minica varieties, both in the methanol and acidic methanol extracts. Hulls from the variety Minica contained a greater amount of methanol-extractable tannins, the quantity of remaining tannins that required acidic methanol for extraction being the same for both varieties.

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The inhibitory effects of hull polysaccharides and tannins of field beans (Vicia faba L.) on the digestion of amino acids, starch and lipid and on digestive enzyme activities in young chicks.

Reproduction, a process essential to maintenance of a species, must be under relatively strict genetic control. This genetic control must ensure that the steps in the reproductive process are repeated with great certainty and precision. Natural selection influenced these steps well before the pig was domesticated over 5000 years ago and humans applied artificial selection. However, nature did not remove genetic variation entirely and humankind has effectively altered the pig to fit social, food and environmental needs. Disciplines Agriculture | Animal Sciences | Biology | Genetics Comments This is a chapter from Rothschild, M. F. and J. P. Bidanel. 1998. Biology and genetics of reproduction. In:Genetics of the Pig, M. Rothschild and A. Ruvinksy (Eds.). CABI Press. pp. 313-343. Posted wtih permission. This book chapter is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/ans_pubs/416 Biology and Genetics of Reproduction M.F. Rothschild andJ.P. Bidanel 1 Iowa State University, Department of Animal Science, 225 Ki/dee Hall, Ames, IA 50011-3150 USA; Institut National de la Recherche Agronomique, Station de Genetique Quantitative et Appliquee 78352 jouy-en-josas Cedex, France Introduction Some Aspects of Pig Reproductive Biology Male Female Traits of interest Chromosomal Abnormalities Between-breed Variation and Crossbreeding Breed differences Crossbreeding Within-breed Genetic Variability Components of genetic variation Genetic correlations Selection experiments Inbreeding Effects of Individual Genes Conclusions and Implications Acknowledgements References 313 314 314 315 316 316 318 318 320

Biology and genetics of reproduction.

Digestibility Characteristics of Isolated Starch from Sorghum and Corn Grain

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Genetic and Phenotypic Relationships between Pubertal and Growth Characteristics of Gilts

Hetero-yellow (HY), red (RED) and brown (BR, high tannin) sorghums were fed dry-rolled or reconstituted (RED and BR only) to evaluate the effect of variety and reconstitution on the site and extent of starch and protein digestion in steers fitted with ruminal, duodenal and ileal cannulae. Processed grains were incorporated into 88% sorghum (DM basis) diets fed at 2% of body weight in a 5 X 5 Latin square. Ruminal fermentation of organic matter, starch and protein tended to be lower for the dry-rolled RED than for either the dry-rolled HY or BR sorghum. Digestion of organic matter (OM) and starch in the small intestine was very low for dry-rolled sorghums. Total tract starch digestibility was lower for the dry-rolled RED sorghum (86.9%) than the BR (90.8%) and HY (91.4%). Nitrogen (N) digestibility ranged from 53.1% for the dry-rolled BR to 64.5% for the HY. Tannins were extensively (95.2%) degraded in the rumen, which may have enhanced fermentation of the BR sorghum. Reconstitution increased (P less than .05) total-tract starch digestion of the RED and tended to increase starch digestion of the BR as well. Total N flow to the duodenum tended to increase with reconstitution, with most of the increase being due to greater (P less than .05) microbial-N. Reconstitution also increased (P less than .05) total-tract N digestibility of the RED. The response to reconstitution for the RED sorghum appeared to be due primarily to an increase (P less than .10) in the extent of fermentation of organic matter and starch in the rumen. Reconstitution of BR, however, enhanced disappearance of starch from the small intestine. In both cases, most (97.3%) of the digestible starch of the reconstituted sorghums had disappeared before the terminal ileum. In contrast, 14.5% (621 g) of the digestible starch of dry-rolled RED disappeared in the large intestine. Sorghum grain variety and reconstitution appear to alter site and extent of starch and protein digestion, which may result in variable performance of cattle fed sorghum grain diets.

Effect of sorghum grain variety and reconstitution on site and extent of starch and protein digestion in steers.

Nutritive Characteristics of Different Varieties of Sorghum and Corn Grains1 ,2

Data were collected from 366 litters produced in a four-breed (Duroc, Yorkshire, Spotted and Landrace) diallel mating system. Purebred and crossbred litters were farrowed during five consecutive (fall and spring) farrowing seasons (fall 1976 through fall 1978). Litters were produced by randomly mating boars of each breed to at least one female of each breed. Litter size and weight at birth, litter size and weight at 42 d and pig survival to 42 d were analyzed. There were significant parity effects for all traits except survival rate, and significant year and season effects for litter size at birth and 42 d and litter weight at 42 d. Large breed of dam differences were detected for most sow productivity traits. Litters from Spotted females were smaller and lighter in weight. Landrace females were most productive in terms of litter weight at weaning and proportion of their pigs raised from birth to weaning. Breed of sire differences were not significant for any trait. Significant heterosis estimates were obtained for litter size and weight at weaning and for survival rate. Crossbred litters had .79 more pigs, were 11.72 kg heavier at weaning and had a 5.56% greater survival rate than the average of all purebreds.

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R. L. Hintz

Papers

Digestibility Characteristics of Isolated Starch from Sorghum and Corn Grain

Genetic and Phenotypic Relationships between Pubertal and Growth Characteristics of Gilts

Effect of sorghum grain variety and reconstitution on site and extent of starch and protein digestion in steers.

Nutritive Characteristics of Different Varieties of Sorghum and Corn Grains1 ,2

Sow productivity comparisons for four breeds of swine: purebred and crossbred litters