Lim Dong-Hyun, Mayakrishnan Vijayakumar, Ki Kwang-Seok, Kim Younghoon, Kim Tae-Il
Dairy Science Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea.
Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 08826, Korea.
Anim Biosci. 2021 Apr;34(4):567-574. doi: 10.5713/ajas.19.0926. Epub 2020 May 12.
In this study we investigated the effect of seasonal thermal stress on milk production and milk compositions between Holstein and Jersey dairy cows under the temperateclimate in Korea.
A total of 9 Holstein lactating dairy cows (2.0±0.11 parity) which had a daily milk yield of 29.77±0.45 kg, and days in milk of 111.2±10.29 were selected similarly at the beginning of the experiments in each season. Also, a total of 9 Jersey lactating dairy cows (1.7±0.12 parity) which had a daily milk yield of 20.01±0.43 kg, and days in milk of 114.0±9.74 were selected similarly at the beginning of the experiments.
Results showed that the average ambient temperature (°C) and temperature-humidity index (THI) were higher in summer, and were lower in winter (p<0.05). The average relative humidity (RH, %) was higher in autumn than that of other seasons (p<0.05). Milk production was significantly decreased (Holstein 29.02 kg/d and Jersey 19.75 kg/d) in autumn than in other seasons (Holstein 30.14 kg/d and Jersey 20.96 kg/d). However, the milk production was negatively correlated in Holstein cows, and positively correlated in Jersey cows with THI values increased from 16 to 80. In addition, milk yield was increased by 15% in Holstein cows and decreased by 11% in Jersey cows with the THI values increased from 16 to 20. The fat and protein content percentage was significantly higher in Jersey milk than in Holstein milk, furthermore the fat and protein content yield was higher in Jersey cow milk than that of Holstein cow's milk with all THIs.
From the study results, we concluded that Jersey cows might be less adaptable to low temperature of the winter, and this would have a negative impact on dairy farmer income since Korea's milk price estimation system places a higher value on milk yield than on milk compositions or sanitary grades.
本研究调查了韩国温带气候下，季节性热应激对荷斯坦奶牛和泽西奶牛产奶量及牛奶成分的影响。
在每个季节实验开始时，分别挑选了9头荷斯坦泌乳奶牛（胎次2.0±0.11），日产奶量为29.77±0.45千克，泌乳天数为111.2±10.29天；以及9头泽西泌乳奶牛（胎次1.7±0.12），日产奶量为20.01±0.43千克，泌乳天数为114.0±9.74天。
结果显示，夏季平均环境温度（℃）和温湿度指数（THI）较高，冬季较低（p<0.05）。秋季平均相对湿度（RH，%）高于其他季节（p<0.05）。秋季的产奶量（荷斯坦奶牛为29.02千克/天，泽西奶牛为19.75千克/天）显著低于其他季节（荷斯坦奶牛为30.14千克/天，泽西奶牛为20.96千克/天）。然而，随着THI值从16增加到80，荷斯坦奶牛的产奶量呈负相关，泽西奶牛的产奶量呈正相关。此外，随着THI值从16增加到20，荷斯坦奶牛的产奶量增加了15%，泽西奶牛的产奶量减少了11%。泽西牛奶的脂肪和蛋白质含量百分比显著高于荷斯坦牛奶，而且在所有THI条件下，泽西奶牛的牛奶脂肪和蛋白质含量产量均高于荷斯坦奶牛的牛奶。
从研究结果来看，我们得出结论，泽西奶牛可能对冬季低温的适应性较差，而这可能会对奶农收入产生负面影响，因为韩国的牛奶价格估算系统对产奶量的重视程度高于牛奶成分或卫生等级。
