中文摘要：

试验旨在研究饲粮β-胡萝卜素不同添加水平对肉牛屠宰性能和胴体品质的影响。选用120头体况良好、平均体重为（381.00±26.01）kg的西门塔尔牛与鲁西黄牛级进杂交2代阉牛,随机分为4组。预试期15d,正试期150d,正试期分为两个阶段：前90d为β-胡萝卜素添加阶段,各组β-胡萝卜素添加水平分别为每头牛0、600、1 200、1 800mg/d,停止添加后进行为期60d的后期跟踪测试,各组均饲喂基础日粮,此阶段又分为两个阶段,每阶段30d。各试验阶段结束时（90d,120d,150d）,每组随机选取10头试验牛进行屠宰并对肝脏内β-胡萝卜素含量、屠宰性能、胴体品质各项指标进行测定。结果显示,日粮添加β-胡萝卜素可极显著提高肉牛肝脏内β-胡萝卜素水平（P〈0.01）;对宰前活重、胴体重和肉骨比等屠宰性能指标无显著影响（P〉0.05）,但屠宰率和净肉率随添加量增高显著升高（P〈0.05）;对胴体品质各项指标均无显著影响（P〉0.05）。后期测试阶段,肝脏内β-胡萝卜素含量逐渐将至对照组水平;对屠宰率和净肉率等屠宰性能指标的影响消失;添加组内背膘厚度显著降低（P〈0.05）,但对眼肌面积、高档肉块占活重比例等其它胴体品质指标无显著影响（P〉0.05）。综合结果数据,在本试验条件下,β-胡萝卜素添加量在1 200-1 800mg/d,停止添加后30d屠宰,对屠宰性能和胴体品质影响效果最佳。

英文摘要：

To evaluate the effects ofβ-carotene（βC）on slaughter performance and carcass quality of beef cattle,one hundred and twenty healthy Simmental and local Luxi yellow cattle second generation crossbred steers with mean live weight of 381.00±26.01 kg were allotted to four treatments.After adaptation phase of 15 days,an experimental period of 150 days was divided into two periods：C supplementation period（90days）,fed standard basic daily rations consisting of C supplemented at 0,600,1 200 and 1800mg/d for each cattle respectively,followed by a tracking test period of 60 days,fed standard basic daily rations without C,the tracking test period was subdivided into two sub-periods further,each with 30 days.At the end of each experimental period（i.e.,days 90,120,and 150）,10 randomly chosen cattle from each group were slaughtered,βC content in the liver,and data on slaughter performance and carcass quality were analyzed.The results showed that after supplementation,liverβC content increased dramatically withβC supplemental levels（P〈0.01）in all the treatment groups;no significant differences were observed in the live weight,carcass weight and ratio of muscle to bone（P〉0.05）,while the dressing percentage and net meat percentage increased significantly with increasing concentration ofβC（P〈0.05）;no significant impact in any indicator of carcass quality were detected（P〉0.05）.In the tracking test period,liverβC content decreased to control group level gradually;no significant differences were detected in any slaughter performance indicator（P〉0.05）;a decrease in back fat thickness was observed in the treatment groups（P〈0.05）,but no significant differences were detected in other carcass quality indicators as LM area and percentage of high-value cuts to live weight（P〉0.05）.In conclusion,C performed best effects on slaughter performance and carcass quality when the supplemental level between 1200 and 1800 mg/d and slaughtered 30 days after supplementation stopped.