A method is proposed for estimating the percentage of dietary protein that is degraded by microbial action in the rumen when protein supplement is added to a specified ration. The potential degradability, p , is measured by incubating the supplement in artificial-fibre bags in the rumen and is related to incubation time, t , by the equation p = a+b (1 – e -ct ). The rate constant k , measuring the passage of the supplement from the rumen to the abomasum, is obtained in a separate experiment in which the supplement is combined with a chromium marker which renders it completely indigestible. The effective percentage degradation, p , of the supplement, allowing for rate of passage, is shown to be p = a +[ bc/(c+k) ] (1- e -(e+k)t ) by time, t , after feeding. As t increases, this tends to the asymptotic value a+bc /( c+k ), which therefore provides an estimate of the degradability of the protein supplement under the specified feeding conditions. The method is illustrated by results obtained with soya-bean meal fed as a supplement to a dried-grass diet for sheep. The incubation measurements showed that 89% of the soya-bean protein disappeared within 24 h and indicated that it was all ultimately degradable with this diet. When the dried grass was given at a restricted level of feeding the allowance for time of retention in the rumen reduced the estimate of final degradability to 71% (69% within 24 h). With ad libitum feeding there was a faster rate of passage and the final degradability was estimated to be 66% (65% within 24 h).

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The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage

Nutrient requirements of poultry

Determination of titanium dioxide added as an inert marker in chicken digestibility studies

A review of interactions between dietary fibre and the intestinal mucosa, and their consequences on digestive health in young non-ruminant animals

This paper examines the nutritional and veterinary effects of tannins on ruminants and makes some comparisons with non-ruminants. Tannin chemistry per se is not covered and readers are referred to several excellent reviews instead: (a) Okuda T et al. Heterocycles 30:1195-1218 (1990); (b) Ferreira D and Slade D. Nat Prod Rep 19:517-541 (2002); (c) Yoshida T et al. In Studies in Natural Product Chemistry. Elsevier Science, Amsterdam, pp. 395-453 (2000); (d) Khanbabaee K and van Ree T. Nat Prod Rep 18:641-649 (2001); (e) Okuda et al. Phytochemistvy 55:513-529 (2000). The effects of tannins on rumen micro-organisms are also not reviewed, as these have been addressed by others: (a) McSweeney CS et al. Anim Feed Sci Technol 91:83-93 (2001); (b) Smith AH and Mackie RI. Appl Environ Microbiol 70:1104-1115 (2004). This paper deals first with the nutritional effects of tannins in animal feeds, their qualitative and quantitative diversity, and the implications of tannin-protein complexation. It then summarises the known physiological and harmful effects and discusses the equivocal evidence of the bioavailability of tannins. Issues concerning tannin metabolism and systemic effects are also considered. Opportunities are presented on how to treat feeds with high tannin contents, and some lesser-known but successful feeding strategies are highlighted. Recent research has explored the use of tannins for preventing animal deaths from bloat, for reducing intestinal parasites and for lowering gaseous ammonia and methane emissions. Finally, several tannin assays and a hypothesis are discussed that merit further investigation in order to assess their suitability for predicting animal responses. The aim is to provoke discussion and spur readers into new approaches. An attempt is made to synthesise the emerging information for relating tannin structures with their activities. Although many plants with high levels of tannins produce negative effects and require treatments, others are very useful animal feeds. Our ability to predict whether tannin-containing feeds confer positive or negative effects will depend on interdisciplinary research between animal nutritionists and plant chemists. The elucidation of tannin structure-activity relationships presents exciting opportunities for future feeding strategies that will benefit ruminants and the environment within the contexts of extensive, semi-intensive and some intensive agricultural systems. (c) 2006 Society of Chemical Industry

Unravelling the conundrum of tannins in animal nutrition and health

Protein metabolism and nutrition.

Principles of pig science

A series of experiments was designed to evaluate inert markers employed in studies of ileal and faecal apparent digestibilities of nitrogen and amino acids in pigs fitted with simple 'T' piece cannulas. Trial 1 assessed the palatability of diets containing (a) 5 g chromic oxide/kg, (b) 1 and (c) 5 g titanium dioxide/kg at two levels of feeding. The results indicated that there were slight problems in terms of period of feed consumption associated with diets (a) and (c), but that these effects were transitory and disappeared following acclimatization, although higher levels of feeding may compound the problem. Trial 2 estimated N balance, faecal apparent digestibility of amino acids as determined by both total collection and ratio of markers, ileal apparent digestibility of amino acids and recovery of markers using diets containing (a) 1 and (b) 5 g Cr2O3/kg, (c) 1 and (d) 5 g TiO2/kg. An additional assessment of acid-insoluble lignin present within the diet was also undertaken. Cr2O3 was associated with the lowest recovery, whilst calculations based on TiO2 gave lower standard errors. Trial 3 examined diurnal variation in digesta sampling and its effect on faecal apparent digestibility of N and amino acids. There were no evident effects. In general, it was concluded that the most appropriate marker to use in studies of this nature was TiO2 at a rate of 1 g/kg.

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Evaluation of inert markers for the determination of ileal and faecal apparent digestibility values in the pig.

Manipulation of rumen fermentation amino acid requirements of ruminants seasonal variation of appetite in ruminants photoperiodic influences on milk production in dairy cows manipulation of milk yield with growth hormone the influence of level and pattern of concentrate input on milk output concentrate feeding and milk composition the effect of dietary fat on milk composition effect of fibre in compound feeds in the performance of ruminants manipulation of milk compostion to meet market needs effect of protein on the health of dairy cows practical aspects of feeding protein to dairy to cows the contribution of grass and conserved forages to the nutrient requirements for milk production factors affecting substitution rates in dairy cows on silage-based rations feeding for high margins in dairy cows some nutritional aspects of high yielding dairy herds factors affecting the feeding value of silage factors affecting the nutritive value of grass silages growth promoters and their importance in ruminant livestock production nutrient requirements of intensively-reared beef cattle meeting the nutrient requirements of beef cattle in forage-based systems of production energy and protein requirements of the ewe.

Recent Developments in Ruminant Nutrition – 2

Impact of immune system activation on growth and optimal dietary regimens of pigs * Benefits of antibiotics in animal feed * Alternatives to antibiotics - the influence of new feeding strategies for pigs on biology and performance * Recent advances in probiotics for pigs * The role of fructo-oligosaccharides in animal nutrition * Feeding short-chain organic acids to pigs * Non-starch polysaccharides in pig diets and their influence on intestinal microflora, digestive physiology and enteric disease * Digestive and metabolic utilization of dietary energy in pig feeds: comparison of energy systems * Nutrition x environmental interactions: predicting performance of young pigs * New approaches with pig weaner diets * Prediction of the energy value of alternative feeds for pigs * Antinutritional factors in the plant proteins of diets for non-ruminants * Utilisation of different fibres in piglet feeds * Fibre in diets of sows * Choice-feeding systems for pigs * Outdoor pigs - their nutrient requirements, appetite and environmental responses * Feeding liquid diets to pigs * Nutrient requirements of modern pig genotypes * Energy - amino acid interactions in modern pig genotypes * Amino acid requirements of breeding pigs * The influence of vitamins on reproduction in pigs * Index

D. J. A. Cole

Papers

Protein metabolism and nutrition.

Principles of pig science

Evaluation of inert markers for the determination of ileal and faecal apparent digestibility values in the pig.

Recent Developments in Ruminant Nutrition – 2

Recent developments in pig nutrition