Energy balance and energy utilization of lactating cows under restricted protein supply and subsequent refeeding

Roehrmoser, G.; Mueller, H.L.; Kirchgessner, M.

Zeitschrift fuer Tierphysiologie Tierernaehrung und Futtermittelkunde 50(4-5): 216-224


Accession: 005360971

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A respiration experiment with 4 pairs of monozygoting twin cows was conducted to determine the effect on the utilization of energy of a 17% deficiency of crude protein for 4 wk. During a subsequent period of realimentation of 3 wk with slight oversupply and a further period of 3 wk with nutrient supply adjusted to lactation trend permanent responses associated with the previously protein undernutrition were examined. On isocaloric energy intake the protein deficient ration resulted in a higher fecal energy by 7.3%. In contrast the excretion of urine energy was substantially reduced by 20% and that of methane by 8.4%. The metabolizability of energy reached 55.6% in protein deficiency compared to 57.5% in the control animals. After realimentation these criteria did not differ between the cows previously protein-deficient and the control twins. Protein deficiency lowered the excretion of milk energy by 2.8 MJ/d (6.1%). However, milk energy related to metabolizable energy was nearly the same in both groups, 33.1% on the protein-deficient ration and 33.6% on the control ration. Body tissue energy was not affected during the protein restrictive phase and averaged to 4.9 MJ/d. Therefore, deficiency of crude protein did not influence the partial efficiency of energy retention (milk + tissue energy) from metabolizable energy. After realimentation there was a tendency to slightly higher partial efficiency in the previously undersupplied cows compared to the control cows. In consequence of advanced pregnancy the efficiency of utilization of energy decreased by about 5% points towards the end of the last experimental period.