Male pre- and post-pubertal castration effect on live weight, components of empty body weight, estimated nitrogen excretion and efficiency in Piemontese hypertrofic cattle

摘要

To evaluate the effect of sexual neutering and age of castration on empty body weight (EBW) components and estimated nitrogen excretion and efficiency, a trial was carried out on 3 groups of double-muscled Piemontese calves: early castrated (EC, 5th month of age), late castrated (LC, 12th month of age) and intact males (IM, control group). Animals were fed at the same energy and protein level and slaughtered at 18th month of age. Live and slaughtering performances and EBW components were recorded, whereas N excretion was calculated by difference between diet and weight gain N content. In live and slaughtering performances, IM showed higher final, carcass and total meat weight than EC and LC (P<0.01). In EBW components, IM showed higher blood and head weight than EC and LC (P<0.01 and 0.05 respectively), and differences were found between EC and LC for head weights (P<0.01). IM showed higher body crude protein (BCP) than EC and LC (P<0.01 and 0.05 respectively), but BCP/EBW ratio was higher only in IM than EC (P<0.05). Estimated N daily gain was higher in IM than EC and LC (P<0.01). Only LC showed higher excretion than IM (P<0.05), and N efficiency was higher in IM than EC and LC (P<0.05 and 0.01 respectively). In conclusion, for the Piemontese hypertrophied cattle castration significantly increases N excretion (+7%) and reduces N efficiency (?15%), leading to a lower level of sustainability.