本試驗採用阿爾拜因、撒能、臺灣黑山羊、波爾雜交、努比亞雜交等五種閹公羊各20頭，其中臺灣黑山羊肥育至45及55kg時各屠宰3頭，其他四品種閹公羊則分別於55、65及75kg時各屠宰3頭，以探討不同品種與屠宰體重對五種臺灣常用閹公羊屠體性狀與肌肉脂肪酸組成之影響。結果顯示，各品種閹公羊之屠宰率隨屠宰體重增加而顯著（P＜0.05）提高，屠體脂肪率亦隨屠宰體重升高而增加。惟屠體精肉率有隨屠宰體重增加而降低之趨勢；閹公羊之屠體脂肪率與骨骼率於品種間存有極顯著（P＜0.01）差異。除臺灣黑山羊外，其餘四品種山羊背最長肌樣肉之粗脂肪與水分含量顯著（P＜0.05）受屠宰體重影響。五品種山羊背最長肌樣肉之不飽和脂肪酸比例均較飽和脂肪酸為高，其中不飽和脂肪酸以C18:1之比例為最高（43.38-55.09%），飽和脂肪酸則以C16:0所佔比例為最高（17.86-27.04%）。由樣肉之感官品評結果發現，臺灣黑山羊有顯著（P＜0.05）較差之風味、嫩度與總接受性，其他四品種間則無顯著差異。綜合本試驗結果，無論是純種之乳閹公羊、純種肉用或雜種肉用閹公羊，其最佳之屠宰體重應為65kg，此結論與閹公羊肥育至65kg出售最符合經濟效益之結果相符合。臺灣黑山羊受限其體型無法肥育至60kg以上，最佳之屠宰體重有待進一步探討。

This study was to investigate the effect of different breeds and slaughter weight scales on carcass characteristics and fatty acids profile of castrated goats in Taiwan. Twenty heads of castrated goat from different breeds, which were Alpine, Saanen, Taiwan black, Boer hybrid, and Nubian hybrid, were fatten at same condition. Three heads out of twenty goats were chosen for slaughter, when individual animal reached its designated slaughter weight. Taiwan black goats, small-frame size, were slaughtered at 45 and 55 kg of live weight due to inborn limitation, while the test of four breeds of goats were slaughtered at 55 ,65 and 75 kg of live weight scales. The results showed that the more goats reached a heaver weight, the more they had a higher dressing percentage. Owing to a heavy slaughter weight of goat had a light meat percentage in goat carcass. On the contrary, the fat percentage in goat carcass was increased when the slaughter weight scales of goat was increased. The slaughter weight of goat significantly affected the percentages of crude fat and moisture contents in M. longissimus dorsi for those breeds of Alpine, Saanen, Boer hybrid and Nubian hybrid. Nevertheless, the percentage of crude protein in M. longissimus dorsi of goat was not affected by breeds or slaughter weight. Percentage of unsaturated fatty acids at M. longissimus dorsi of goat was higher than that of saturated fatty acids in breeds. Meanwhile, percentage of oleic acid and palmitic acid at M. longissimus dorsi of goat were the highest in each unsaturated fatty acid or saturated fatty acid groups, respectively. Fatty acids profile in M. longissimus dorsi from five goat breeds were affected by slaughter weight scales and breeds. Furthermore, there was a significantly interaction between this two factors. The panel test of M. longissimus dorsi in Taiwan black goat, which included the sensory scores of flavor, tenderness, and overall acceptability, were pooler than that of others four breeds. The result suggested that 65 kg of live weight of those four breeds, which included Alpine, Saanen, Boer hybrid and Nubian hybrid, was the appropriate body weight for slaughter. These four breeds of goat can obtain maximum economical benefits if they were fattened to 65 kg BW and slaughter. However, the appropriate slaughter body weight of Taiwan black goat need further research.