通风喷雾对热应激肉牛生长性能、营养物质表观消化率、瘤胃发酵参数及血清指标的影响

Effects of Mechanical Ventilation and Water Spraying on GrowthPerformance, Apparent Nutrient Digestibility, Rumen FermentationParameters and Serum Indexes of Heat-Stressed Beef Cattle

本试验旨在研究通风喷雾对热应激肉牛生长性能、营养物质表观消化率、瘤胃发酵参数及血清指标的影响。选取12月龄左右、体重(420.22±46.67)kg的西门塔尔杂交公牛32头,随机分为2组,即对照组和通风喷雾组,每组16个重复,每个重复1头牛。试验期间2组肉牛大部分时间处于轻度或中度热应激环境中,试验组牛舍安装风机和喷雾装置,对照组牛舍不做任何处理。试验期共45 d,其中预试期15 d,正试期30 d。结果显示:1)与对照组相比,通风喷雾组肉牛的呼吸频率(RR)和直肠温度(RT)极显著降低(P<0.01)。2)与对照组相比,通风喷雾组肉牛的生长性能和营养物质表观消化率无显著变化(P>0.05),但平均日增重(P=0.089)和干物质采食量(P=0.075)均有显著升高的趋势。3)与对照组相比,通风喷雾组的肉牛瘤胃液pH极显著升高(P<0.01),丁酸浓度和乙酸/丙酸(A/P)比值显著升高(P<0.05)。4)与对照组相比,通风喷雾组肉牛血清中总胆固醇(TCHO)、皮质酮(CORT)含量及谷丙转氨酶(ALT)活性极显著降低(P<0.01),甘油三酯(TG)含量显著降低(P<0.05),高密度脂蛋白(HDL)含量显著提高(P<0.05)。5)与对照组相比,通风喷雾组肉牛血清中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性及总抗氧化能力(T-AOC)极显著提高(P<0.01),丙二醛(MDA)含量极显著降低(P<0.01)。6)与对照组相比,通风喷雾组肉牛血清中肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)和白细胞介素-6(IL-6)含量极显著降低(P<0.01),免疫球蛋白A(IgA)含量极显著升高(P<0.01),免疫球蛋白G(IgG)含量显著升高(P<0.05)。综上所述,在热应激条件下对牛舍进行通风喷雾能够降低肉牛直肠温度和呼吸频率,提高肉牛血清中免疫球蛋白含量和抗氧化水平,减少体内自由基累积,从而有效缓解热应激对肉牛生理和免疫功能以及抗氧化能力造成的负面影响。

This experiment was to investigate the effects of mechanical ventilation and water spraying on growth performance,apparent nutrient digestibility,rumen fermentation parameters and serum indexes of heat-stressed beef cattle.Thirty-two Simmental crossbred bulls aged about 12 months with body weight of(420.22±46.67)kg were randomly divided into 2 groups,they were control group(CON group)and mechanical ventilation and water spraying group(MVWS group),with 16 replicates per group and 1 cattle per replicate.Beef cattle in the two groups were exposed to mild or moderate heat stress environment most of the time during the experiment.The cattle barn of the MVWS group was equipped with mechanical ventilation and water spraying,while no treatment was done in the CON group.The experiment lasted for 45 days,with a pre-test period of 15 days and a formal test period of 30 days.The results showed as follows:1)compared with the CON group,the respiratory rate(RR)and rectal temperature(RT)of the beef cattle in the MVWS group were extremely significantly reduced(P<0.01).2)Compared with the CON group,the growth performance and nutrient apparent digestibility of beef cattle in the MVWS group had no significant changes(P>0.05),however,the average daily gain(P=0.089)and dry matter intake(P=0.075)showed a significant increase trend.3)Compared with the CON group,the beef cattle in the MVWS group had an extremely significant increase in rumen fluid pH(P<0.01),and had a significant increase in the concentration of butyrate and acetate/propionate(A/P)ratio(P<0.05).4)Compared with the CON group,the contents of total cholesterol(TCHO)and cortisol(CORT),alanine aminotransferase(ALT)activity in the serum of beef cattle in the MVWS group were extremely significantly decreased(P<0.01),and the triglyceride(TG)content was significantly decreased(P<0.05),while the high-density lipoprotein(HDL)content was significantly increased(P<0.05).5)Compared with the CON group,the activities of superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)and total antioxidant capacity(T-AOC)in the serum of beef cattle in the MVWS group were extremely significantly increased(P<0.01),while the content of malondialdehyde(MDA)was extremely significantly decreased(P<0.01).6)Compared with the CON group,the contents of tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β)and interleukin-6(IL-6)in the serum of beef cattle in the MVWS group were extremely significantly decreased(P<0.01),while the content of immunoglobulin A(IgA)was extremely significantly increased(P<0.01),and the content of immunoglobulin G(IgG)was significantly increased(P<0.05).In conclusion,under the heat stress conditions,mechanical ventilation and water spraying in cattle barn can reduce the rectal temperature and respiratory rate of beef cattle,increase the contents of immunoglobulins and antioxidant level in the serum,reduce the accumulation of free radicals in the body,and effectively alleviate the negative effects of heat stress on the physiological and immune function and antioxidant ability of beef cattle.