Effects of castration and fattening period on growth performance and carcass characteristics in Iranian goats

A completely randomized design was used to study the effect of castration at three months of age and fattening periods (2, 3, 4, 5 or 6 months of fattening) on the feedlot performance and carcass characteristics of Fars native male goat kids. Six kids were slaughtered on the first day of the experiment (day 0), and 60 kids were divided into two groups (castrate or intact) of similar mean live weight, and housed in individual pens and fed a pelleted total mixed diet ad libitum. At the end of each fattening period, 6 kids per treatment were randomly selected for slaughter and evaluation of carcass quality. The mean live body weight for each fattening period between the castrate and intact groups was significantly different (P < 0.01). However, the average daily gain (ADG), daily feed intake and feed conversion ratio (FCR) for each period between the two treatment groups did not differ. The mean live body weight, daily weight gains, daily feed intake and feed conversion ratio were however significantly affected by the fattening period. Dressing percentages after 2, 3 and 4 months of fattening were not significantly different between the castrate and intact groups, but significantly different after Sand 6 months of fattening. The mean carcass lean and fat percentages during certain periods between the castrated and intact groups were significantly different, but the percentage bone in each period between the two groups was not significantly different. Overall, the mean carcass lean and fat percentages were significantly different between the intact (68.8% and 8.5%, respectively) and castrated (65.4% and 12.5%. respectively) animals. The mean carcass bone percentage was not significantly different between the intact (21.5%) and castrated (20.9%) animals. With castration, the internal fat and carcass fat content increased and carcass lean content decreased. As judged by a taste panel, meat from the castrated kids recorded a milder smell than meat from the intact males (P < 0.05). Although the stress of castration had a negative effect on live body weight at the onset of the experiment, a fattening period of 3 months is recommended with castration, given the development of meat odour in goats slaughtered after longer fattening periods. (C) 2011 Elsevier B.V. All rights reserved.