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HOW COWS CAN ADAPT TO DON How can we best support them by nutritional means?
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by Gwendolyn Jones, Anco Animal Nutrition Competence
uminants are regarded as quite resistant to fusarium mycotoxins such as deoxynivalenol (DON) because of the detoxifying potential of rumen microbes. However, the detoxification capacity of rumen microbes depends on a functional rumen. New feed solutions showed in research trials that they can help to reduce the negative effects of DON on milk component yields in high producing dairy cows, which are more susceptible to the impact of DON.
Economic impact of DON in dairy cows
Scientific literature reveals, that unlike aflatoxin, there is very little carry-over from DON in dairy rations into milk. However, DON in rations for dairy cows, has been shown to decrease milk fat and increase somatic cell counts (SCC). DON is known to increase oxidative stress, which in dairy cows has been related to oxidative mammary tissue damage and increased SCC. There is further evidence that DON affects feed intake, rumen fermentation and microbial protein yield, which can again affect feed efficiency and milk component yields. Increasingly, the levels of protein and fat in milk are being recognised as major determinants of milk price. As a result, milk component levels are important factors in herd management and directly impact farm income. Furthermore, US studies have shown that many herds are producing components below average for their market and their breed, which presents an opportunity to improve component production and income from milk sales.
Limitations of the cow’s endogenous defense
Greater resistance to DON in ruminants has been attributed to the detoxifying role of the microbial population in the rumen. Rumen microbes effectively transform DON into nontoxic metabolites. However, detoxification capacity for DON by rumen bacteria can be compromised in high producing dairy cows, which are fed greater amounts of concentrates and where feed 70 | September 2017 - Milling and Grain