Abstract
This paper presents results from a study of the age and weight at puberty of Thai does. A randomized block $3{\times}3$ factorial design was used. Factors were genotype (Thai Native; TN, 75% TN $\times$ 25% Anglo-Nubian; AN and 50 TN $\times$ 50% AN does), year of kidding (1989, 1990 and 1991) and birth type (single or twin) as a block. It was shown that there were no significant (p > 0.05) difference in age at puberty among genotypes ($167.6{\pm}6.0$, $157.6{\pm}7.0$ and 160.0 = 4.7 days for TN, 75% TN $\times$ 25% AN and 50% TN $\times$ 50% AN does, respectively) and between birth types. However, does kidded in 1991 had significantly (p < 0.01) longer age at puberty ($194.0{\pm}7.4$ days) than did does kidded in 1989 ($143.0{\pm}4.5$ days) or in 1990 ($148.1{\pm}5.7$ days). There was an interaction effect between genotype and year. Fifty % TN $\times$ 50% AN does had significantly (p < 0.05) higher weights at pubery ($17.2{\pm}0.4kg$) than those of TN($14.3{\pm}0.5kg$ and 75% TN $\times$ 25% AN ($14.4{\pm}0.6kg$) does. There was no significant difference in weights at puberty between TN and 75% TN $\times$ 25% AN does. There was no effect of birth type on weight at puberty. There was an interaction effect between genotype and year of kidding on age and weight at puberty and on growth rate from birth to weaning.