利用非参数检验法分析热应激和胎次对奶牛生产性能的影响

为了解南方地区热应激和胎次对奶牛产奶量、乳脂率、乳蛋白率和体细胞数的影响,本文收集了南方某大型牧场一个生产年度的DHI数据、气候数据、生产数据,采用SPSS 25软件中的非参数检验法,分析了热应激和胎次对奶牛产奶量、乳成分和体细胞数的影响。结果表明:乳脂率随热应激程度加大而升高,产奶量反之,不同热应激程度之间存在明显差异(P<0.05);无热应激月份比有热应激月份的乳蛋白率和体细胞数低(P<0.05)。1胎奶牛产奶量最低(P<0.05),3胎产奶量最高(P<0.05);体细胞数随胎次增加呈上升趋势,1胎体细胞数最低(P<0.05);2胎、5胎乳脂率较高,2胎乳蛋白率显著高于1、3、4胎(P<0.05),但和5胎差异不明显(P>0.05)。

Analysis of the Effects of Heat Stress and Parity on the Production Performance of Cows with Nonparametric Tests

This experiment was conducted to study the effects of heat stress and parity on milk yield,the milk fat ratio,milk protein ratio and somatic cell count.The DHI data of these cows were collected from a pasture in Guangdong province,the date include DHI measured data,climate data,production data of one year.We processed those data by Nonparametric test.Experimental results showed that heat stress and parity significantly influenced the milk yield and milk composition.In terms of heat stress,the milk fat rate increased with the increase of heat stress,and the milk yield was conversely,and there were significant differences among different degrees of heat stress(P<0.05).The milk protein rate and somatic cell number were lower in months without heat stress than in months with heat stress(P<0.05).In terms of the influence of parity on milk yield,the milk yield of the first-fetal cows was the lowest(P<0.05),and the milk yield of third-fetal cows was the highest(P<0.05).In terms of the influence of fetal number on somatic cells,somatic cells showed an upward trend with the increase of fetal number,and the first-fetal cell was the lowest(P<0.05).The milk fat rate were higher in the second-fetal and the fifth-fetal.The milk protein ratio of the second-fetal was significantly higher than that of 1、3、4 fetus(P<0.05),but not significantly different from that of the fifth-fetal(P>0.05).