Publisher's Synopsis
The three papers in the General Nutrition session had the unifying theme of meat quality, animal health and production efficiency. Consumers judge the quality of meat by its appearance, texture and flavour. The most important factor at the point of sale is appearance and this can be greatly affected by lipid oxidation. With increasing consumer demand for unsaturated fatty acids in meat, lipid oxidation becomes more of a problem. Evidence presented in the first paper shows that supplementation of diets with vitamin E can significantly improve the keeping qualities of meat in poultry, pigs and cattle. Another consumer concern is the presence of antibiotics in meat. Feed antibiotics for pigs have been banned in Sweden and the third paper looks at how attention to detail can maximise the efficiency of production without growth promoters. Of particular importance are correctly balanced rations, health status, housing and management. The other paper in this session concentrated on the health of young animals; in particular, the response of the immune system to plant proteins. It is postulated that systemic hypersensitivity and allergic reactions can be reduced or eliminated by strategic exposure to lectins. The Poultry session comprised two papers on topical subjects. The first of these addressed the problem of wheat interfering with the digestion of fats. High inclusion levels of cereals can increase digesta viscosity and inhibit the movement of bile salts and lipase within the intestines. This problem can be overcome to some extent by including enzymes in the diet to reduce viscosity. In turkeys, continued genetic selection for growth rate has led to birds reaching market weights at increasingly younger ages. Since breast meat is the most valuable part of the carcass, it is important to look at slaughter ages which will give optimum yields of this portion. The relationships between growth rate, slaughter age and breast-meat yield were examined in the second paper of this session. The Ruminant session was entirely devoted to dairy cows this year. Dairy farmers in most parts of the developed world are currently facing reductions in milk prices with potentially increasing input costs. It is therefore important that we continue to examine the efficiency of utilisation of raw materials and production systems in general. The first paper examined the role of fats in dairy cow diets. Fats are high-energy sources that have a vital role to play in providing sufficient energy for the modern dairy cow. However, it is important to appreciate the effects they may have on rumen fermentation and production responses. The potential for modifying the fat composition of milk through manipulation of dietary fats is also explored. This could be one way of increasing product value by supplying milk for niche markets. The second paper discussed the use of starch in dairy rations. Like fats, starch can increase the energy content of diets, but it can also have negative effects on forage digestibility. The potential for directly increasing glucose supply by feeding starch that bypasses rumen fermentation is discussed, as is the effects of starch on milk protein concentration. Other papers in this session relate developments in the French INRA system of feeding dairy cows and amino acid nutrition. These two papers are complementary and both provide a great deal of useful information that should improve the accuracy of meeting the requirements of high-yielding cows. The INRA system has been developed into a more integrated system that now includes net energy, metabolisable protein and intake prediction. The paper on amino acids shows how ration formulation for dairy cows is approaching the level precision enjoyed by non-ruminant nutritionists. The other paper in this session analysed systems of feeding and managing high-yielding dairy cows in the US. Cows in the US are characterised by high genetic merit and to reach their potential it is necessary to pay careful attention to nutrition and feed ingredients. Added boosts to yield come from the increasing use of frequent milking and BST. These provide even greater challenges for feed formulators and the shortcomings in current feed evaluation systems are discussed.
