EFFECTS OF AGE AND SEX ON BODY COMPOSITION OF THAI NATIVE AND CROSS-BRED GOATS

This paper presents results from a study of the effects of age and sex on body and carcass composition of different goat genotypes. A completely randomized $3{\times}3{\times}2$ factorial design was used. Factors were genotype (Thai Native; TN, $50%TN{\times}50%$ Anglo-Nubian (AN) and $25%TN{\times}75%AN$ goats), age ($206{\pm}8$, $349{\pm}9$ and $428{\pm}8days$ or 6.9, 11.6 and 14.3 months, respectively) and sex (male and female). It was shown that TN kids had significantly higher (p < 0.05) hind percentage (7.9%) compared with $50%TN{\times}50% AN$ (7.2%) and $25%TN{\times}75%AN$ (7.1 %) kids. TN kids had a significantly (p < 0.05) higher heart percentage (0.44%) than that of $25%TN{\times}75%AN$ kids (0.38%). However, there was no significant difference in heart percentage between TN and $50%TN{\times}50%AN$ and between $50% TN{\times}50%AN$ and $25%TN{\times}75%AN$ kids. TN and $50%TN{\times}50%AN$ kids had significantly higher (p < 0.05) carcass muscle content (63.1 and 63.7%, respectively) than did $25%TN{\times}75%AN$ kids (59.9%). Kids at 6.9 months of age had significantly higher percentages of hide, feet, intestinal tract, liver, heart, kidneys and carcass bone than those of kids at 11.6 and 14.3 months of age. There were no significant differences in these characteristics between kids at 11.6 and 14.3 months of age. However, kids at 11.6 and 14.3 months of age had significantly higher percentages of omental fat, dressing carcass, muscle, total fat (subcutaneous + intermuscular + kidney and pelvic fat), muscle to bone ratios (MBR), and muscle plus fat to bone ratios (MFBR) than those of kids at 6.9 months. Males had significantly higher gut contents, but lower percentages of liver, omental fat and heart. Prediction equations were developed relating empty body weight (EBW) to hot carcass weight and some dissectible carcass fractions.