Feed International - November/December 2012 - 12
10 | Ingredients by Ioannis Mavromichalis, Ph.D. Six points for optimal use of soybeans in piglet feed Soybeans are an obvious feed choice for pig diets. However, formulating for piglets can be tricky. No matter how expensive feed ingredients become, soybeans remain one of the most economical sources of protein in pig diets. Soybeans are cultivated for their high oil content, because their protein is of good quality, and because they complement the protein of cereals so well that this blend has become the ideal feed for most pig diets worldwide. However, like most other feedstuffs, soybeans are not without their problems. The major issue with soybeans is the presence of a great number of anti-nutritional factors that reduce digestibility and, eventually, growth, productivity and profitability, even if fed to mature pigs. Unless soybeans are thermally processed very well, these anti-nutritional factors are not destroyed easily. Unfortunately, with overcooking also comes denaturation of the useful proteins, something that defeats the purpose of cooking in the first place. Thus, optimal processing conditions are required to obtain a balance between protein quality and reduction of anti-nutritional factors. These anti-nutritional factors have the most impact in young pigs, especially those around the time of weaning. In this case, things become even more complicated. As Like most feedstuffs, soybeans are not without their problems. it happens, the otherwise useful soybean proteins cause an allergic reaction that triggers the gut immune system as if it were invaded by pathogenic microorganisms. This negative reaction leads to inflammation and diarrhea. Quite often the inflammation damages the lining of the intestines, thus greatly facilitating the attachment of pathogens and the absorption of their exotoxins. Although the whole effect lasts no more than a week, until the immune system develops "immunity," the damage is long-term and multifaceted when complicated with pathogenic bacterial infection, as is the case more often than not. meal in the first diet post-weaning, increasing rapidly to 15 percent in the second diet and so on. This approach requires a high level of feed intake to ensure minimal impact as the negative effects of soybean protein tend to be more severe when feed intake is below maintenance requirements. The benefits of this program are 1) low-cost formulas, 2) rapid adaptation to soybean protein, and 3) minimal number of diet changes. In contrast, the negative aspects include higher chances of diarrhea outbreaks, especially in farms with below ideal health status - which is the case for many places worldwide. Two schools of thought Gradual adaptation To combat this problem, two schools of thought have evolved. One calls for the introduction of soybean protein immediately after weaning (assuming piglets had no or minimal exposure to pre-weaning creep feed). Although the introduction of soybean protein post-weaning is recommended to be a gradual process, this method requires the presence of about 10 percent soybean A more gentle approach to the same problem calls for zero levels of any kind of soybean products in the first diet postweaning, followed by a second diet with low levels of soybean protein in the form of refined products (such as soy protein isolate that has virtually no anti-nutritional factors). Here too, the key phrase is gradual adaptation, but the main difference is the WATTAgNet.com | November/December 2012
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