藏羊和小尾寒羊生长性能及血液生理指标对不同能量低氮日粮的响应特性

Effect of dietary with different energy level to Tibetan and small-tailed han sheep on the growth performance and blood physiological indexes under the low nitrogen condition

为了研究氮胁迫下、不同能量水平日粮对藏羊(Tibetan sheep)和小尾寒羊(small-tailed han sheep)生长性能和血液生理指标的影响,试验选取1.5岁、体重分别为(50.13±2.42)、(50.30±2.42)kg和体况相近的健康藏羊和小尾寒羊羯羊各24头,藏羊和小尾寒羊都随机分为低能(LE)、中低能(MLE)、中高能(MHE)和高能(HE)4个试验处理组,每组6个重复。试验饲粮的粗蛋白(crude protei,CP)含量相近(6.97%)而能量不同,其消化能(digestive energy,DE)水平分别为8.21、9.33、10.45和11.57 MJ·kg-1。试验分预饲期14d,正试期42d。结果表明,1)氮胁迫下,营养物质摄入量不受绵羊品种的影响(P>0.05)。随着日粮能量水平升高,DE和有机物(organic matter,OM)摄入量线性增加(P<0.01),中性洗涤纤维(neutral detergent fibre,NDF)和酸性洗涤纤维(acid detergent fibre,ADF)线性降低(P<0.01),其余养分指标不受影响(P>0.05)。2)氮胁迫下,藏羊平均日增重(average daily gain,ADG)显著高于小尾寒羊(P<0.01),且两者均随着日粮能量水平升高而线性增加(P<0.01)。当日粮能量处于中低能水平时,藏羊ADG为正值而小尾寒羊仍为负增重。3)氮胁迫下,藏羊白细胞(white blood cell,WBC)、红细胞(red blood cell,RBC)、血红蛋白(hemogolbin,HGB)、红细胞压积(hematocrit,HCT)及血小板(platelet,PLT)均显著低于小尾寒羊(P<0.05),WBC、RBC、HGB及HCT随日粮能量水平的提高而极显著降低(P<0.01),而PLT随日粮能量水平的提高而极显著增加(P<0.01)。上述研究结果表明,氮胁迫下,与小尾寒羊相比,藏羊日粮能量水平增加后的生长性能改善效果更好;在血液生理指标方面,藏羊对于营养和环境胁迫,具有更强的适应性。

In order to study the effects of different dietary energy level on the growth performance and blood physiological indexes of Tibetan sheep and small-tailed han sheep under the nitrogen stress condition,healthy castration male Tibetan sheep(n=24)and small-tailed han sheep(n=24)of 1.5 years old with similar body weight(50.13±2.42 kg,50.30±2.42 kg)were selected for this study,and then divided into four groups(LE,MLE,MHE,HE),each group included 6 sheep.Diets were formulated as four different digestible energy levels(8.21,9.33,10.45,11.57 MJ·kg-1,respectively)and with similar crude protein(CP)content(6.97%).The study lasted for 56 d,including pre-feeding period of 14 d and the official period of 42 d.The results showed that under the nitrogen stress condition,the nutrient intake was not affected by sheep breeds(P>0.05).The intake of DE and organic matter(OM)were significantly increased linearly(P<0.01)and the NDF and ADF were significantly decreased linearly(P<0.01)with the increase of dietary energy level,the remaining nutrient indexes were not affected(P>0.05).The average daily weight gain(ADG)of the Tibetan sheep was significantly higher than that of the small-tailed han sheep(P<0.01),and both of them increased linearly with the increase of dietary energy under the nitrogen stress condition(P<0.01).When the dietary energy is in the MLE level,the ADG of Tibetan sheep is positive,but the small-tailed han sheep is still negative.The blood physiological indexes showed that number of white blood cells(WBC),red blood cell(RBC),hemoglobin(HGB),hematocrit(HTC)and platelet(PLT)were significantly lower than that of small-tailed han sheep(P<0.05),the WBC,RBC,HGB and HTC decreased significantly and the PLT increased significantly with the increase of dietary energy levels under the nitrogen stress condition(P<0.01).The results indicated that the growth performance of Tibetan sheep was improved more better than that of the small-tailed han sheep with the increase of dietary energy level under the nitrogen stress condition;In the blood physiological indexes,the Tibetan sheep has a stronger adaptability to nutritional and environmental stress than small-tailed han sheep.