In order to determine the optimal supplemental levels of methionine and cysteine in diets and their correlations of influences on growth and hair coat development of Rex rabbits, the related indices of growth and hair development were measured. A total of 315 new born Rex rabbits with the same birthday were allocated into 7 groups at random in litters. There were 7 replicates in each group and 6 rabbits in each replicate. The rabbits in the control group were fed a basal diet which contained 0. 24% methionine and 0. 23% cysteine, and the rabbits in the experimental groups were fed the diets supplemented with 0.10% , 0. 25% and 0.40% methionine or cysteine based on the basal diet, respectively. The feeding trial lasted from birth to 151 days old. The results showed as follows; supplementation of sulphur-amino acids could increased the body weight at 151 days of age and average daily gain, and above indices in the 0. 25% and 0. 40% groups had significant differences compared with the control group (P <0. 05). With the supplemental level of sulphur-amino acids increasing, the feed to gain ratio showed a declining trend (P >0. 05), while the average daily feed intake showed an increasing trend (P>0.05). Compared with the control group, completion ratio of molt and hair coat density in the 0. 25% and 0. 40% groups were significantly increased (P <0. 05 or P <0. 01), but no significant differences were found between 0. 25% and 0. 40% groups (P >0. 05). From the perspective of hair coat scores at 92 and 151 days of age, supplementation of sulphur-amino acids could not significantly boost the hair coat quality of rex rabbits (P >0. 05) , and hair coat quality only showed an increasing trend with the supplemental level increasing. No significant differences were found in the above indices between methionine and cysteine groups with the corresponding levels (P >0. 05). Growth curve-fitting suggested that supplemental level of sulphur-amino acids could only change the maximum growth rate, but had little effect on the adult body weight. These results indicate that both of methionine and cysteine can promote growth and enhance hair coat development of Rex rabbits, and 0.25% dosage is the optimal supplemental level. Moreover, the promotive effect of the methionine and cysteine almost is alike, and the equivalent cysteine may entirely replace methionine. However, supplementation of sulphur-amino acids only can not significantly boost the hair coat quality of Rex rabbits.%本试验旨在通过测定生长及被毛发育相关指标,确定蛋氨酸及半胱氨酸在獭兔饲粮中的最优添加水平,并了解它们在影响獭兔生长及被毛发育方面的相互关系.选择同天出生的仔獭兔294只,以窝为单位随机分为7组,每组7个重复,每个重复6只.对照组獭兔饲喂基础饲粮(含半胱氨酸0.23％、蛋氨酸0.24％),试验组獭兔分别饲喂在基础饲粮中添加0.10％、0.25％和0.40％半胱氨酸或蛋氨酸的试验饲粮.饲养周期为初生到151日龄.结果表明:饲粮中添加含硫氨基酸提高了獭兔的150日龄体重及平均日增重,0.25％、0.40％组与对照组相比存在显著差异(P＜0.05).随着含硫氨基酸添加水平的增加,獭兔的料重比表现为下降的趋势(P＞0.05),平均日采食量则表现为上升的趋势(P＞0.05).与对照组相比,0.25％和0.40％组换毛完成率和被毛密度显著或极显著提高(P＜0.05或P＜0.01),但0.25％与0.40％组间差异不显著(P＞0.05).从92日龄和151日龄被毛评分来看,獭兔被毛品质随含硫氨基酸添加水平的增加仪表现出提高的趋势,组间差异不显著(P＞0.05).上述各指标在蛋氨酸与半胱氨酸各对应水平间均无显著差异(P＞0.05).通过生长曲线拟合分析,在2种含硫氨基酸的添加水平内,添加水平仅改变獭兔的最大生长速度,而对成年体重的影响不大.由此得出,蛋氨酸与半胱氨酸对獭兔生长与被毛发育均具有促进作用,均以0.25％添加水平为最优,且促进效果几乎同等,等量半胱氨酸可以完全代替蛋氨酸.但是,仅通过添加含硫氨基酸不能显著地改变獭兔的表观被毛品质.
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