Nutrition And The Environment

Nutrient management is an issue in many parts of the world. In the United States, nitrogen (N) and phosphorus (P) are the nutrients currently regulated. A full lactation study was done, examining different protein feeding strategies for dairy cows.[6] Milk production was similar among three treatments, even though total N intake was 25 kg less and manure N excretion decreased 21 kg on one of the treatments. A 3-lactation study found that decreasing P from 0.47% to 0.39% of the total diet did not affect milk production.1-7-1 A 5-year field study in a commercial dairy herd reported a 17% decrease in manure N excretion even though animal numbers increased by 33%.[8] P excretion decreased by 28% during this same period. Milk production per cow increased by about 9% during this same time. These results indicate that there are opportunities to reduce nutrient excretion to the environment in dairy herds without decreasing milk production.

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