Deposition and utilization of nitrogen in cows during and after excessive provision of protein. 2. Effect of an incorrect protein supply for lactating cows and its consequences

Kreuzer, M.; Kirchgessner, M.

Zeitschrift fur Tierphysiologie, Tierernahrung und Futtermittelkunde 53(5): 270-279


ISSN/ISBN: 0044-3565
Accession: 001560029

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During 3 successive periods, each including 8-day quantitative collection of faeces, urine and milk, 18 lactating Simmental X Red Holstein Friesian cows had a theoretically optimum protein supply (control) or a protein surplus of 25% followed by optimum supply or by a 25% deficit, then the optimum amount. All diets were equal in energy, fibre and other nutrients. Mean daily consumption of nitrogen with control treatment was 330 g and with surplus or deficit about 55 g more and 74 g less. With excessive protein surplus N was largely excreted in urine, whereas urinary N was reduced with dietary deficit. Faecal N was not affected by protein supply. There was no clear after-effect of incorrect protein supply, but adjustment to new diet took several days. Breakdown of body protein was higher with deficient than with optimum supply. Excessive protein or refeeding after deficiency did not increase N deposition. Utilization of N for retention and milk production decreased with rising protein supply.