Abstract :
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 5 and 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.
