Growth and testis development of male Cashmere and Angora goats.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 19 GROWTH AND TESTIS DEVELOPMENT OF MALE CASHMERE AND ANGORA GOATS P. D. BALL, J. A ROBERTSON and A. J. RITAR Dept of Primary Industry, PO Box 180, Kings Meadows, Tas. 7249. The onset of puberty in male ruminants is determined by breed and by liveweight. Testicular growth is an indicator of this pubertal development. In this study, testis growth was examined in relation to age, liveweight, and rearing husbandry of young Cashmere and Angora bucks. Male Cashmere (n=79) and Angora (n=l 1) kids (born in Oct.-Nov. 1989) were reared using 3 husbandry strategies; early weaning (EW) at 50 + 0.8 days (11.5 ,+ 0.4 kg), rearing on a foster feeder (FF) using a milk substitute until 48 * 2.9 days (11.4 + 0.5 kg), normal weaning (NW) at 92 + 2.6 days (14.2 ,+ 0.5 kg). After weaning, EW and FF kids were given unrestricted access to supplementary hay and pellets until 96 days old. All kids were then grazed on improved pasture as one group. Cashmere kids were stratified on date of birth and birth code and then randomly allocated to 5 slaughter ages (43, 96, 133, 214 and 246 days old). Angora kids were slaughtered at one age (243 days). Animals were weighed at birth and at regular intervals to weaning and slaughter. No significant differences were observed in mean liveweight, carcass weight or left testis weight between rearing groups (EW, FF and NW), and the pooled results are presented in Table 1. Mean liveweight, carcass weight and testis weight increased significantly (PcO.05) between age groups up to 214 days, although differences in carcass weight between ages 96 and 133 days were not significant. During the period up to 214 days old the rate of testis weight gain was greater than the rate of increase in liveweight and carcass weight. Whilst liveweight decreased significantly (P<O.O5) between 214 and 243 days due to poor nutritional conditions, the decrease in testis weight was not significant. Testis weight of the Cashmeres was highly correlated (PcO.01) with age (R*=0.75), liveweight (R*=0.73) and carcass weight (R*=0.61). Table 1. Mean liveweight (kg), carcass weight (kg) and left testis weight (g) at slaughter of Cashmere and Angora bucks (age in days) Angoras at 243 days old had significantly lower liveweights (PcO.05) and testis weights (PcO.01) than Cashmeres at 246 days old. However, the relationship between testis weight and liveweight was similar. The dressing percentage (carcass weightniveweight x 100) of the Angoras (36%) was also significantly lower (PcO.001) than that of the Cashmeres (41%) at 246 days old. No detrimental effect of early weaning or foster feeder rearing on liveweight or testis weight was detected. Testis weight was closely related to liveweight and carcass weight, overriding any age effect in the young buck. The growth and development of the Angoras was significantly slower than that of the Cashmeres. 285