Modern dairy cows deserve modern vitamin nutrition

Modern dairy production practices require a more intense approach to daily nutrition for animals that are often kept indoors producing milk yields that can reach 50 liters per day.

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In the old days, it was believed that dairy cows that grazed all day for fresh forage required no further nutrients. That was true: The bugs in the rumen would produce enough nutrients, including vitamins, to sustain their host. Again, back then, this was correct based on the level of available knowledge, genetics and methods of production.

Using this same concept today ignores a very significant fact: Modern dairy cows no longer live only on green forage and they no longer produce 10 liters of milk per day. Modern dairy production practices require a more intense approach to daily nutrition for animals that are often kept indoors producing milk yields that can reach 50 liters per day. Modern ruminant nutritionists have done a great job revisiting most nutrients along this thinking, and now is high time to focus on the part of vitamin nutrition for modern dairy cows.

When it comes to determining total vitamin requirements (total = ingredients + supplementation), it has always been an uphill battle for ruminant researchers. This is why scientific bodies like the U.S. National Research Council have been reserved in establishing and then revising such requirements over the years. Instead, it is easier to work with vitamin supplementation because it largely ignores amounts supplied by natural ingredients. This might not be entirely correct, but it remains convenient. Such allowances differ greatly among authorities and many are the result of years of experience, based on different conditions, and thus, they tend to differ by region.

Fat-soluble vitamins

When it comes to vitamins A, D, E and K, we actually consider (more times than not) the amount of vitamins that actually exist in forage and concentrated ingredients. Fresh forage will contain higher levels, whereas stored forage less. The longer the storage period and the worse the storage conditions, the lower the levels will be. It is generally considered that a higher milk yield will always necessitate a higher level of supplementation, but this is only one of the variables that need to be taken into account. In contrast, higher levels are almost invariably recommended for specific cases, as will be explained below. In general, most veteran nutritionists prefer to err on the side of over-supplementation with fat-soluble vitamins, perhaps thinking any savings on vitamins might not be a reason good enough to risk losing a customer โ€“ and as we all know, nutrition is always blamed first for all kinds of trouble. Nevertheless, this does not mean this is the correct approach as vitamins are not free of charge and, in an industry that strives constantly for profits, everything counts.

Water-soluble vitamins

Here research is even more confusing, but we would not expect anything less for an animal like the cow, which has its own nutrient factory โ€“ the rumen. Indeed, some research has indicated that extra niacin, for example, can warranty a higher milk yield, but other reports mentioned niacin does not survive the rumen. Is it then the bugs that need more niacin? Here it is interesting to note that protected niacin did not offer as much benefit in some trials as it did in others. Perhaps we should start discussing B vitamin nutrition for rumen function and not for milk yield? Nevertheless, some B vitamins (often protected) are supplied to high-yielding cows and these include niacin, choline and biotin. The latter is also recommended for hoof problems as part of a more general leg health program. Other B vitamins may also be found in some high-end premixes for marketing purposes. Finally, some believe that one of the major roles of yeast played in rumen health is the provision of B vitamins to the rumen bacteria. So, there is a lot that we still do not know about rumen function and B vitamins.

Vitamins and immunity

In the past 20 or so years, the issue of immunity has become central in animal nutrition research. It has been noted in cattle that at the time around parturition, the immune system is generally down, and this coincides with low(er) circulating levels of some vitamins. Supplementation with certain vitamins during such times resulted in better immune responses โ€“ and subsequently improved health and productivity โ€“ at least in some trials. Thus, it is often in peri-parturition supplements that we see elevated levels of vitamins (mostly A, E and some B vitamins). Perhaps this is not a cure, but certainly a helping hand for a difficult period in the life of the animal. Again, the marketing noise around this issue makes science difficult to find its place in practice as this is a tool and not a standard fix.

Vitamins and mastitis

One of the most common observations associated with low circulating levels of vitamins has been mastitis โ€“ a perennial problem with dairy cattle. Adding extra vitamins often, but not always, prevents or alleviates this problem. We cannot claim that with vitamins alone we can resolve mastitis, but they do help in some cases. Now, what vitamins actually help is rather difficult to establish, but the same suspects (A, E and some of the B group) are frequently found in such support supplements.

Antioxidation

The two most powerful vitamin antioxidants that we routinely supply to dairy cows are beta-carotene (provitamin A) and vitamin E. The first is often supplied at enough quantities by fresh forage, but the second is seldom enough for high-yielding animals. Modern production methods (high feed intake, high yield, stressful housing conditions, diseases, etc.) increase the oxidation burden of all farm animals, including dairy cows. And although there is a plethora of antioxidants that the organism is producing, the role of vitamin E in cellular membrane integrity (that is, keeping the organism up straight) can never be overemphasized. Here, as with other species, most knowledgeable nutritionists prefer to err toward over-supplementation, especially when milk prices are high. Luckily, the issue of oxidation and the need to supply enough antioxidants (including minerals such as selenium) is rightly acknowledged by ruminant nutritionists, something their fellow monogastric nutritionists are still struggling to come into terms with.

Time to revisit vitamin nutrition

If cows graze all day in the country and belong to a breed that produces just enough milk for homemade butter and cheese, then a powerful vitamin nutritional supplement will probably be not necessary. But, if you own an enterprise with hundreds or thousands of dairy cows producing an unprecedented amount of milk (and you already push for more), then it is a good idea to employ the services of a qualified nutritionist to revisit your vitamin nutrition, especially if the last time this was done was in the previous century.

This does not always mean vitamin levels should be increased. Modern marketing has pushed supplementation levels often to unprecedented high levels that are simply not warranted. Or, it might be the case that the problem associated with increased vitamin supplementation has been resolved and it is now time to return to normal levels. At any rate, using the right level for the right purpose is a sure way to maximize performance and profitability.

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