3-METHYL-HISTIDINE AND CREATININE IN THE URINE OF LACTATING DAIRY-COWS DURING AND AFTER PROTEIN AND ENERGY DEFICIENCY

The influence of protein and energy restriction followed by realimenta tion on urinary excretions of 3-methyl-hisitidine (3MH) and creatinine were studied in 20 lactating dairy cows. Renal excretions of 3MH and creatinine increased with rising body weight (BW[kg]) of the animals ( 3MH[mg/day] = 67 + 0.285 x BW; Creatinine[g/day] = 1.43 + 0.021 x BW). Relative to body weight the renal excretions of 3MH and creatinine in creased in underfed animals and decreased transiently during the reali mentation period. There was an inverse relationship to daily protein b alance (PB[g/day]) (3MH[mu g/day/kg] = 422 - 0.272 x PB; Creatinine[mg /day/kg] = 24.3 - 0.0097 x PB).