摘要
本试验旨在研究烟酸对低海拔地区热应激麦洼牦牛生长性能、营养物质表观消化率及血液指标的影响。选取1.5岁、体重[(222.00±16.65)kg]相近、健康的麦洼公牦牛12头,随机分为对照组和烟酸组,每组6个重复,每个重复1头牛。试验期为7、8、9月,对照组饲喂基础饲粮,烟酸组于8和9月时在基础饲粮中添加0.049 g/kg BW烟酸。预试期7 d,正试期90 d。结果表明:1)牛舍全期的温湿度指数(THI)>72,表明牦牛是处于热应激环境,8月THI显著高于7和9月(P<0.05),9月THI显著低于7和8月(P<0.05)。2)7~8月,随着热应激强度的升高,对照组牦牛呼吸频率显著升高(P>0.05),烟酸组牦牛呼吸频率并未显著升高(P>0.05);与对照组相比,烟酸组牦牛血清中热休克蛋白70、促肾上腺皮质激素和皮质醇含量显著下降(P<0.05),牦牛应激反应有所减轻。3)8月,烟酸组牦牛干物质采食量和平均日增重显著高于对照组(P<0.05),瘤胃pH显著低于对照组,瘤胃氨态氮含量显著高于对照组(P<0.05),同时随着9月热应激强度的降低,烟酸组牦牛瘤胃总挥发性脂肪酸、乙酸、丙酸、丁酸和氨态氮含量均显著升高(P<0.05)。4)8月,与对照组相比,添加烟酸显著提高粗脂肪和粗蛋白质表观消化率(P<0.05)。5)8~9月,添加烟酸可使牦牛全血中红细胞分布宽度变异系数、白细胞数及血清白细胞介素-1β和肿瘤坏死因子-α含量显著低于对照组(P<0.05),全血平均红细胞体积、平均红细胞血红蛋白含量和血小板分布宽度显著高于对照组(P<0.05),缓解了机体所需的血氧供应和炎症发生。综上所述,添加烟酸可降低牦牛的热应激反应,提高牦牛在低海拔地区的热适应性。添加烟酸后能提高热应激牦牛的营养物质消化率,改善机体血红细胞适应血氧供给,降低炎症反应,保证其在热应激期的生长。
This experiment was conducted to investigate the effects of niacin on the growth performance,nutri ent apparent digestibility and blood indexes of yak under heat stress fattening at low altitudes.Twelve healthy male Maiwa yaks with similar body weight of(222.00±16.65)kg at 1.5 years of age were selected,divided into control group and niacin group,with 6 replicates in each group and 1 yak in each replicate.The experi ment period was July,August and September.The control group were fed a basal diet,and niacin group were fed the basal diet added 0.049 g/kg BW niacin in August and September.The experiment had a 7 day adaption period and a 90 day test period.The results showed as follows:1)the temperature humidity index(THI)in barn during whole period was more than 72,which indicated that the yak were under heat stress,THI in Au gust was significantly higher than that in July and September(P<0.05),and THI in September was signifi cantly lower than that in July and August(P<0.05).2)With the increase of heat stress intensity from July to August,the respiratory rate of yak in control group increased significantly(P<0.05),but the respiratory rate did not significantly increase in niacin group(P>0.05);compared with the control group,the contents of heat shock protein 70,adrenocortical hormone and cortisol in the niacin group significantly decreased(P<0.05),and the stress response of yak was reduced.3)Adding niacin significantly increased the dry matter intake and average daily gain in August(P<0.05),the rumen pH was significantly lower than that in the control group(P<0.05),the ammonia nitrogen content was significantly higher than that in the control group(P<0.05),the contents of total volatile fatty acids,acetic acid,propionic acid,butyric acid and ammonia nitrogen in the niacin group significantly increased with the decrease of heat stress in September(P<0.05).4)Adding niacin increased significantly the apparent digestibility of crude fat and crude protein in August(P<0.05).5)From August to September,adding niacin significantly decreased the variation coefficient of red blood cell distribu tion width in whole blood,white blood cell count,interleukin 1βand tumor necrosis factor αcompared with the control group(P<0.05),and the average red blood cell volume,mean red blood cell hemoglobin content and platelet distribution width were significantly higher than those in the control group(P<0.05),relieving the blood oxygen supply and inflammation.In conclusion,adding niacin can reduce the heat and humidity stress of yak,and improve the thermal adaptability of yak in low altitude agricultural areas.The addition of niacin can improve the digestibility of nutrients in the yak during the heat stress period,improve the body’s red blood cells to adapt to blood oxygen supply,reduce inflammation,and ensure the growth during the heat stress peri od.
作者
王雪莹
王之盛
薛白
王立志
彭全辉
邹华围
祝伊枭
周芯宇
曹广
代秦丹
师俊华
汪成
WANG Xueying;WANG Zhisheng;XUE Bai;WANG Lizhi;PENG Quanhui;ZOU Huawei;ZHU Yixiao;ZHOU Xinyu;CAO Guang;DAI Qindan;SHI Junhua;WANG Cheng(Key Laboratory of Low Carbon Culture Production in Cattle in Sichuan,Animal Nutrition Institute,Sichuan Agricultural University,Chengdu 611130,China)
出处
《动物营养学报》
CAS
CSCD
北大核心
2020年第5期2228-2240,共13页
CHINESE JOURNAL OF ANIMAL NUTRITION
基金
国家现代农业(肉牛/牦牛)产业技术体系(CARS 37)。
关键词
热应激
牦牛
烟酸
生长性能
营养物质表观消化率
血液指标
heat stress
yak
niacin
growth performance
nutrient apparent digestibility
blood indexes
