Halli Kathrin, Brügemann Kerstin, Bohlouli Mehdi, König Sven
Institute of Animal Breeding and Genetics, Group Animal Breeding, Justus-Liebig-University, Giessen, Germany.
Transl Anim Sci. 2020 Aug 5;4(3):txaa148. doi: 10.1093/tas/txaa148. eCollection 2020 Jul.
Climate change causes rising temperatures and extreme weather events worldwide, with possible detrimental time-lagged and acute impact on production and functional traits of cattle kept in outdoor production systems. The aim of the present study was to infer the influence of mean daily temperature humidity index (mTHI) and number of heat stress days (nHS) from different recording periods on birth weight (BWT), 200 d- and 365 d-weight gain (200 dg, 365 dg) of calves, and on the probability of stillbirth (SB), and calving interval (CINT) of their dams. Data recording included 4,362 observations for BWT, 3,136 observations for 200 dg, 2,502 observations for 365 dg, 9,293 observations for the birth status, and 2,811 observations for CINT of the local dual-purpose cattle breed "Rotes Höhenvieh" (RHV). Trait responses on mTHI and nHS were studied via generalized linear mixed model applications with identity link functions for Gaussian traits (BWT, 200 dg, 365 dg, CINT) and logit link functions for binary SB. High mTHI and high nHS before autumn births had strongest detrimental impact on BWT across all antepartum- (a.p.) periods (34.4 ± 0.79 kg maximum). Prolonged CINT was observed when cows suffered heat stress (HS) before or after spring calvings, with maximum length of 391.6 ± 3.82 d (56 d a.p.-period). High mTHI and high nHS during the 42 d- and 56 d a.p.-period implied increased probabilities for SB. We found a significant ( < 0.05) seasonal effect on SB in model 3 across all a.p.-periods, with the highest probability in autumn (maximum of 5.4 ± 0.82% in the 7 d a.p.-period). Weight gains of calves (200 dg and 365 dg) showed strongest HS response for mTHI and nHS measurements from the long-term postnatal periods (42 d- and 56 d-periods), with minimum 200 dg of 194.2 ± 4.15 kg (nHS of 31 to 42 d in the 42 d-period) or minimum 365 dg of 323.8 ± 3.82 kg (mTHI ≥ 60 in the 42 d-period). Calves born in summer, combined with high mTHI or high nHS pre- or postnatal, had lower weight gains, compared with calves born in other calving seasons or under cooler conditions. Highest BWT, weight gains, and shortest CINT mostly were detected under cool to moderate climate conditions for mTHI, and small to moderate nHS. Results indicate acute and time-lagged HS effects and address possible HS-induced epigenetic modifications of the bovine genome across generations and limited acclimatization processes to heat, especially when heat occurs during the cooler spring and autumn months.
气候变化导致全球气温上升和极端天气事件频发，可能对户外养殖系统中牛的生产和功能性状产生有害的时间滞后和急性影响。本研究的目的是推断不同记录期的平均每日温度湿度指数（mTHI）和热应激天数（nHS）对犊牛出生体重（BWT）、200日龄和365日龄体重增加量（200 dg、365 dg），以及对其母畜死胎概率（SB）和产犊间隔（CINT）的影响。数据记录包括4362条BWT观测值、3136条200 dg观测值、2502条365 dg观测值、9293条出生状态观测值，以及2811条当地兼用牛品种“红高地牛”（RHV）的CINT观测值。通过广义线性混合模型应用研究了mTHI和nHS对性状的响应，对高斯性状（BWT、200 dg、365 dg、CINT）使用恒等连接函数，对二元SB性状使用logit连接函数。秋季出生前的高mTHI和高nHS对所有产前（a.p.）时期的BWT产生的有害影响最强（最大为34.4±0.79 kg）。当母牛在春季产犊前后遭受热应激（HS）时，观察到CINT延长，最长可达391.6±3.82天（产前时期为56天）。产前42天和56天期间的高mTHI和高nHS意味着SB概率增加。我们发现在模型3中，所有产前时期对SB都有显著（<0.05）的季节效应，秋季概率最高（产前7天期间最大为5.4±0.82%）。犊牛体重增加量（200 dg和365 dg）对长期产后时期（42天和56天期间）的mTHI和nHS测量显示出最强的HS响应，200 dg最小值为194.2±4.15 kg（42天期间nHS为31至42天）或365 dg最小值为323.8±3.82 kg（42天期间mTHI≥60）。与在其他产犊季节或较凉爽条件下出生的犊牛相比，夏季出生且产前或产后mTHI高或nHS高的犊牛体重增加量较低。对于mTHI处于凉爽至温和气候条件且nHS较小至中等时，大多检测到最高的BWT、体重增加量和最短的CINT。结果表明存在急性和时间滞后的HS效应，并揭示了HS可能导致的牛基因组跨代表观遗传修饰以及对热的有限适应过程，特别是当在较凉爽的春季和秋季出现高温时。
