Male pre- and post-pubertalcastration effect on liveweight, components ofempty body weight,estimated nitrogen excretionand efficiency in Piemontesehypertrofic cattle

摘要

To evaluate the effect of sexual neutering andage of castration on empty body weight (EBW)components and estimated nitrogen excretionand efficiency, a trial was carried out on 3groups 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 thesame energy and protein level and slaughteredat 18th month of age. Live and slaughtering performancesand EBW components were recorded,whereas N excretion was calculated by differencebetween diet and weight gain N content.In live and slaughtering performances, IMshowed higher final, carcass and total meatweight than EC and LC (P<0.01). In EBW components,IM showed higher blood and headweight than EC and LC (P<0.01 and 0.05 respectively),and differences were found between ECand LC for head weights (P<0.01). IM showedhigher body crude protein (BCP) than EC andLC (P<0.01 and 0.05 respectively), butBCP/EBW ratio was higher only in IM than EC(P<0.05). Estimated N daily gain was higher inIM than EC and LC (P<0.01). Only LC showedhigher excretion than IM (P<0.05), and N efficiencywas higher in IM than EC and LC(P<0.05 and 0.01 respectively). In conclusion,for the Piemontese hypertrophied cattle castrationsignificantly increases N excretion (+7%)and reduces N efficiency (-15%), leading to alower level of sustainability.