Tanniniferous Dichrostachys cinerea fruits do not require detoxification for goat nutrition: in sacco and in vivo evaluations

This study investigated the potential of Dichrostachys cinerea fruits as a protein supplement in semi-arid areas of Zimbabwe. The tanniniferous fruits were treated with aqueous solutions of polyethylene glycol (PEG) or sodium hydroxide (NaOH). Both treatments increased the soluble fraction, rate of degradation and effective degradability (ED) of nitrogen (N) in sacco. The PEG effects were higher than the NaOH effects (e.g. a 25% vs. 6% increase in effective N degradabilities, respectively). Five treatments were evaluated in a N-balance trial using Matebele goats: ground, PEG- or NaOH-treated D. cinerea fruits, a commercial protein supplement (CPS) and no supplement. Animals offered ground fruits or CPS retained most N (3.7 or 4.1 g N/day, respectively), while those offered NaOH- or PEG-treated fruits retained significantly less N (2.7 or 1.0 g/day, respectively). Unsupplemented animals were in negative N balance (-2.4 g/day). PEG treatment deactivated the tannins more than the NaOH treatment. PEG treatment resulted in excessive protein degradation in the rumen leading to high urine N loss. It is concluded that the D. cinerea fruits were beneficial for goat N-nutrition and that the tannins did not require inactivation. D. cinerea fruits can, therefore, replace the expensive commercial protein supplement. It is also suggested that the collection and grinding of fruits could be used as a management tool to control bush encroachment. (C) 2004 Elsevier B.V. All rights reserved.

Nutrition of chicks and layers

When formulating least-cost poultry diets, ME concentration should be optimised by an iterative procedure, not entered as a fixed value. This iteration must calculate profit margins by taking into account the way in which feed intake and saleable outputs vary with ME concentration. In the case of broilers, adjustment of critical amino acid contents in direct proportion to ME concentration does not result in birds of equal fatness. To avoid an increase in fat deposition at higher energy levels, it is proposed that amino acid specifications should be adjusted in proportion to changes in the net energy supplied by the feed. A model is available which will both interpret responses to amino acids in laying trials and give economically optimal estimates of amino acid inputs for practical feed formulation. Flocks coming into lay and flocks nearing the end of the pullet year have bimodal distributions of rates of lay, with the result that calculations of requirement based on mean output will underestimate the optimal amino acid input for the flock. Chick diets containing surplus protein can lead to impaired utilisation of the first-limiting amino acid. This difficulty can be avoided by stating amino acid requirements as a proportion of the protein.

Unravelling the conundrum of tannins in animal nutrition and health

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

Tannin-containing plants for animal nutrition and health

Abstract 13.12.1

Unravelling the conundrum of tannins in animal nutrition and health

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

Octanol-water partition coefficients for predicting the effects of tannins in ruminant nutrition

Tannins can cause beneficial or harmful nutritional effects, but their great diversity has until now prevented a rational distinction between tannin structures and their nutritional responses. An attempt has been made to study this problem by examining the octanol-water solubilities of tannins. A relatively simple HPLC method has been developed for screening mixtures of plant tannins for their octanol-water partition coefficients (K-ow coefficients). Tannins were isolated from the fruits and leaves of different Acacia, Calliandra, Dichrostachys, and Piliostigma species, which are known to produce beneficial or harmful effects. The K-ow coefficients of these tannins ranged from 0.061 to 13.9, average coefficients of variation were 9.2% and recoveries were 107%. Acacia nilotica fruits and leaves had the highest K-ow coefficients, that is, 2.0 and 13.9, respectively. These A. nilotica products also have high concentrations of tannins. The combined effects of high octanol solubilities and high tannin concentrations may explain their negative effects on animal nutrition and health. It is known that compounds with high octanol solubilities are more easily absorbed into tissues, and it is, therefore, proposed that such compounds are more likely to cause toxicity problems especially if consumed in large quantities. According to the literature, tannins in human foods tend to have low K-ow coefficients, and this was confirmed for the tannins in Piliostigma thonningii fruits. Therefore, unconventional feeds or browse products should be screened not only for their tannin concentrations but also for low octanol-water partition coefficients in order to identify nutritionally safe feeds and to avoid potentially toxic feeds.

The challenges for molecular nutrition research 1: linking genotype to healthy nutrition

Nutrition science finds itself at a major crossroad. On the one hand we can continue the current path, which has resulted in some substantial advances, but also many conflicting messages which impair the trust of the general population, especially those who are motivated to improve their health through diet. The other road is uncharted and is being built over the many exciting new developments in life sciences. This new era of nutrition recognizes the complex relation between the health of the individual, its genome, and the life-long dietary exposure, and has lead to the realisation that nutrition is essentially a gene - environment interaction science. This review on the relation between genotype, diet and health is the first of a series dealing with the major challenges in molecular nutrition, analyzing the foundations of nutrition research. With the unravelling of the human genome and the linking of its variability to a multitude of phenotypes from " healthy'' to an enormously complex range of predispositions, the dietary modulation of these propensities has become an area of active research. Classical genetic approaches applied so far in medical genetics have steered away from incorporating dietary effects in their models and paradoxically, most genetic studies analyzing diet-associated phenotypes and diseases simply ignore diet. Yet, a modest but increasing number of studies are accounting for diet as a modulator of genetic associations. These range from observational cohorts to intervention studies with prospectively selected genotypes. New statistical and bioinformatics approaches are becoming available to aid in design and evaluation of these studies. This review discusses the various approaches used and provides concrete recommendations for future research.

Biomarkers of the intake of dietary polyphenols: strengths, limitations and application in nutrition research

In order to establish firm evidence for the health effects of dietary polyphenol consumption, it is essential to have quantitative information regarding their dietary intake. The usefulness of the current methods, which rely mainly on the assessment of polyphenol intake using food records and food composition tables, is limited as they fail to assess total intake accurately. This review highlights the problems associated with such methods with regard to polyphenol-intake predictions. We suggest that the development of biological biomarkers, measured in both blood and urine, are essential for making accurate estimates of polyphenol intake. However, the relationship between dietary intakes and nutritional biomarkers are often highly complex. This review identifies the criteria that must be considered in the development of such biomarkers. In addition, we provide an assessment of the limited number of potential biomarkers of polyphenol intake currently available.