Relationship between microclimate and cow behavior and milk yield under low-temperature and high-humidity conditions
Relationship between microclimate and cow behavior and milk yield under low-temperature and high-humidity conditions
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低温高湿条件下微气候与奶牛行为及产奶量的关系
DOI：
10.3389/fevo.2023.1058147
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发表时间：
2023
影响因子：
3.5
通讯作者：
Yukun Sun
中科院分区：
文献类型：
--
作者：
Jiamei Song;Qingyuan Yu;Xiaolin Wang;Yiqiang Wang;Yonggen Zhang;Yukun Sun
本研究旨在探讨低温高湿条件下不同胎次奶牛的温湿指数、产奶量、反刍时间和活动能力与温度、相对湿度的关系。在这项研究中，每天的样本数量由畜棚中所有健康奶牛确定，胎次和产奶天数（DIM）分别在5和305之间。根据胎次和DIM对奶牛指标进行分类后，采用箱形图法筛选和剔除离群值，采用二元回归模型对产奶量指数（MYI）中的MY进行标准化，剔除DIM对MY的影响。最好的双变量回归模型的基础上，最低赤池信息标准被用来分析行为参数，MYI，和小气候指标之间的关系，为每个奇偶校验。在0°C以上低温小气候的牛舍中，高RH与初产和经产奶牛的MYI呈负相关，与初产和经产奶牛的AT和经产奶牛的RT呈正相关（p < 0.05），因此RH是影响奶牛MYI、RT和AT的显著因素。经产奶牛滞后2天的日平均T、THI与MYI呈显著正相关（p < 0.05）。以多胎次AT与RH的拐点值71.9作为RH的上限值，有利于提高各胎次奶牛的舒适度和MY。与MYI和RT相比，AT具有更高的小气候指标R2，因此可以作为评估LTHH的较好指标。经产母牛与T（R2 = 0.0807）和THI（R2 = 0.1247）的R2比较，经产母牛的MYI与T（R2 = 0.2833）和THI（R2 = 0.3008）的R2较高。因此，经产奶牛对T和THI更敏感。初产奶牛的MYI至T和THI的拐点值大于经产奶牛，表明初产奶牛对T和THI的耐受范围小于经产奶牛。因此，在研究LTHH下MY、T和THI之间的关系时，应考虑奇偶性。
This study aimed to evaluate the relationship between temperature (T), relative humidity (RH), and temperature and humidity index (THI), milk yield (MY), rumination time (RT), and activity (AT) of dairy cows in different parities under low temperature and high humidity (LTHH). In this study, the number of samples each day was determined by all healthy cows in the barn with parity and days in milk (DIM) within 5 and 305, respectively. The box plot method was used for screening and removing outliers of dairy cow indicators after classification according to parity and DIM. To remove the effect of DIM on MY, a bivariate regression model was used to standardize the MY in milk yield index (MYI). The best bivariate regression model based on the lowest Akaike information criterion was used to analyze the relationship between behavioral parameters, MYI, and microclimate indicators for each parity. In the barn with the microclimate at a low temperature above 0°C, high RH was negatively correlated with MYI in primiparous and multiparous cows but positively correlated with AT in primiparous and multiparous cows and RT in multiparous cows (p < 0.05), so RH was a significant factor related to MYI, RT, and AT of cows. The 2-day lagged daily average T and THI were correlated with MYI in primiparous cows (p < 0.05). The inflection point value of 71.9 between AT and RH in the multiparity as the upper limit of RH was beneficial for improving comfort and MY in all parity dairy cows. Compared with MYI and RT, AT had a higher R2 with a microclimate indicator, so it could be used as a better indicator for assessing the LTHH. Comparing the R2 of multiparous cows to T (R2 = 0.0807) and THI (R2 = 0.1247), primiparous cows had higher R2 in MYI to T (R2 = 0.2833) and THI (R2 = 0.3008). Therefore, primiparous cows were more susceptible to T and THI. The inflection point values for MYI to T and THI were greater in primiparous cows than in multiparous cows, indicating that primiparous cows had a smaller tolerance range to T and THI than multiparous cows. Thus, parity should be considered when studying the relationship between MY, T, and THI under LTHH.