Nitrogen balance and nitrogen utilization of dairy cows during and after excess of energy supply 2. communication on the influence of excessive energy supply of lactating cows and its consequences
Kaufmann, T.E.G.; Kirchgessner, M.
Journal of Animal Physiology and Animal Nutrition 57(5): 251-261
ISSN/ISBN: 0931-2439 Accession: 005985958
The aim of the experiment was to assess the effects of an excessive energy supply of 20 MJ NEL over 4 weeks, replicated two times, on N balance and N utilization using four pairs of monozygotic twins in their second lactation. Also it was examined, if there are consequences of the overfeeding in following periods with standard nutrient supply. Patterns of fecal and urinary excretion were complementary. In the energetically overfed group N intake was nearly the same (-11 g), fecal N output slightly raised by 12,5 g N/d. However, retained nitrogen was slightly higher (+7 g), because urinary nitrogen output decreased overproportionally by 31 g. Raising the energy supply without concomitant higher N intake resulted in statistically non significant, but unequivocal better utilization of N for retention and milk production. Clear residual effects of excess energy on the investigated parameters were not found.