Effect of heat stress on the behavioral and physiological patterns of Small-tail Han sheep housed indoors

Abstract

This study was conducted to investigate the effects of heat stress on the behavioral and physiological patterns in Small-tail Han sheep housed indoors in summer without climate control. Sixteen adult animals were allocated into two groups of eight animals, based on sex: one group of eight rams and one group of eight ewes. Temperature-humidity index (THI) was used to assess the degree of heat stress. All sheep were subjected to a 10-day pre-experimental period of habituation to the experimental feed and environment. Physiological parameters monitored were respiratory rate (RR), rectal temperature (RT), and heart rate (HR). Blood chemistry parameters were also recorded, including plasma minerals and blood metabolites, from jugular vein blood samples. Behavioral parameters were lying, standing, excreting, drinking, foraging, walking, and ruminating. The research findings showed that there were some significant differences of behavior (standing, P = 0.001; walking, P = 0.049; ruminating, P = 0.010), physiology (RR, P = 0.0001; HR, P = 0.002; RT, P = 0.03;) and plasma minerals and blood metabolites (sodium, P = 0.047; phosphorus, P = 0.002; T4, P = 0.041; cortisol, P = 0.0047; triglyceride, P = 0.009) between ram and ewe and that heat stress also significantly affected (P < 0.05) standing, lying, foraging and drinking behavior, all of the physiological parameters and some of the blood chemistry parameters (chlorides, sodium, phosphorus, total protein, tetraiodothyronine, cholesterol, triglyceride, creatinine, cortisol, and glucose). These results indicate that ewe has better high-temperature tolerance than ram, and heat stress can alter behavioral and physiological patterns in Small-tail Han sheep housed indoors. These changes may allow the sheep to adapt better to the ambient temperature.

Effect of Shearing Wool and the Hot Months of the Year on some Production Characteristics in Turkish Awassi Ewes

“…The results of the concentration of the hormone cortisol indicate a variation in the metabolic rate as a result of the variation in the concentration of the cortisol hormone. This is agree with (17) showed that the decrease in the concentration of the hormone cortisol in the ewe blood plasma contributed to reducing the metabolic rate and thus reducing heat production, while it works to increase metabolic rates. This result is agree with (18) referred absence of significant differences in the weight increase between the shearing off and non-shear groups, despite the recording of mathematical differences that indicated that the shear group gave a higher weight than the non shear group.…”

Transcriptomic Analysis Provides Novel Insights into Heat Stress Responses in Sheep

“…Fewer studies have been performed on HTR4 with regard to body temperature regulation, but it has been shown in animals to exert important regulatory effects in gastrointestinal sensitivity, memory, and food intake, among others [23]. Under heat stress, sheep exhibited reduced food intake and rumination activities, which further reduced the amount of heat generated by metabolism so as to maintain a stable body temperature [6,9]. During this period, HTR4 might play a significant role.…”

“…Long-term high temperatures and excessively warm weather generate serious heat stress for animals. Heat stress directly or indirectly affects animal physiology, production, and health, among others [1,2,3], which is manifested by physiological features such as gasping for breath, accelerated respiration, elevated heart rate, rising rectal temperature, increasing in-vivo oxidative metabolism, and water and electrolyte disturbance [4,5,6,7]. Regarding reproduction, it can also cause reduced food intake, weight loss, and declining fertility [8,9,10], as well as declining immunity and disease resistance [11,12].…”

Effect of Postmortem Phases on Lamb Meat Quality: A Physicochemical, Microstructural and Water Mobility Approach

“…Fifty-four male sheep carcasses (8 mon of age, Small-Tail Han sheep) with the same feeding system (drylot feeding with the same commercial diet) were randomly collected at a local commercial abattoir in Hebei, China. The Small-Tail Han sheep is a predominant local sheep variety and widely raised in many provinces of China, which originated from Mongolia Sheep and carefully cultivated for a long time in northern China ( Li et al, 2018 ). The 54 carcasses were allocated randomly to three groups for sampling in pre-rigor (45 min postmortem), rigor mortis (24 h postmortem) and post-rigor (72 h postmortem) with 18 carcasses in each group.…”