Published in Scientific Works. Series C. Veterinary Medicine, Vol. LXI
Written by Mircea NICOLAE, Smaranda POP, Cosmin ȘONEA
The study was done on 40 Holstein calves after weaning and followed the effects of lower protein level of rations on some breeding parameters. It was a pre-experimental period of 3 weeks, when all animals were fed by classic rations, reaching about 87 kg body weight. The experience was conducted in two periods of 12 and 10 weeks, respectively. In the first period, the animals were divided in two experimental groups (20 cap. each one), one fed a normal protein level in ration (NP) and the other with a low protein level in ration (LP). In the 2nd period, the animals were divided in 4 experimental groups: NP_NP (normal protein level in both periods of experience), NP_LP (normal protein level in the first period and low in the second), LP_NP (low protein level in the first period and normal in the second) and LP_LP (low protein levels in both experimental periods). Calves were fed ad libitum by a corn-silage-based compound diet. The latter had 20% CP (in DM) in NP diet or 10% CP in LP diet. The entire ration had 14.7% CP (in DM) in the normal situation and 9% CP if protein was restricted. In terms of reducing the level of protein, decreases feed intake, lowest in group LP_LP, 72.2 g DM/kg kg0.75 during the 2nd period. LP_NP group recorded, in the second part of the experience, the greatest increase in weight, 1329 g/day, as against (?) NP_NP group, 1131 g/day, and a difference between the two groups (which ones?) of 17.5%, which demonstrates the compensatory growth. The whole experience, considering the weight gain of NP_NP group (1118 g/day) a reference element (100%), NP_LP group achieved 71%, LP_NP achieved 72% and LP_LP group achieved only 34%. Regarding the specific consumption of protein in the whole experience, it was 563 g CP/kg gain in group NP_NP and 793 g CP/ kg gain in group LP_NP.
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