Monday, July 3, 2017
How to stop wasting vitamins and trace elements in animal feed.
Modern nutrition knowledge allows nutritionists to tailor vitamin and trace mineral supplementation to actual animal requirements, adjusting safety margins to real field conditions. Vitamins and trace minerals are routinely added in almost every commercial feed for all animal species, making their manufacturing, distribution, marketing and sales a global industry worth billions. Although their cost is relatively small, most would argue it is less than 2 percent of total feed cost; it is not insignificant — especially in an industry that often records losses instead of profits. Thus, every prudent nutritionist would be wise to constantly evaluate the vitamins and trace minerals added, their most efficient form and, of course, their payback in terms of animal productivity and health. The recent report of the National Research Council’s Subcommittee in Swine Nutrition (2012) repeats the findings of the previous version (1998) that there is still considerable lack of meaningful research concerning the actual vitamin and trace mineral requirements of pigs. The relevant publication for poultry dates from 1994, which makes it 20 years old now, and rather of academic interest only. On the other hand, poultry breeder recommendations are nothing more than educated guesses, based on their desire for their genetics to always perform at top speed. Therefore, more research is needed to fill this gap in our knowledge of vitamins and trace minerals, but funding is usually diverted to more trendy topics or additives. The most common trace minerals added to diets are iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), iodine (I) and selenium (Se). Although several other trace and ultra trace minerals (e.g., chromium, cobalt, boron, vanadium) have an established physiological role, their dietary essentiality cannot be easily proven because they are required at extremely low amounts. Interestingly, soybean meal and phosphates contain enough iron, copper and manganese to more than cover requirements for some animal classes without further supplementation, even in low-phosphorus diets without phytase. Furthermore, most common diets contain enough copper for most animals. The only real concern in trace mineral supply is with iodine and selenium, especially when animals consume feedstuffs grown in selenium-poor areas. Clearly, little thought has been given to body stores later in life as sources of micronutrients before slaughter. One such example is vitamin B12 that requires at least 5 years to be totally depleted — clearly finishing animals do not require B12 until their last days! Furthermore, the role of microbial synthesis and intestinal absorption of vitamins of microbial origin has been overly underestimated — a prime example is rabbits that can benefit from the recycling of their cecal contents. Other species also consume feces (however disgusting we might consider it), and clearly animals housed in galvanized cages have different requirements in zinc than those in pasture or traditional pens.more