High environmental temperatures cause heat stress in ewes, resulting in thermoregulatory problems. In this study, the thermoregulatory responses of Blackbelly adult ewes (G1, n = 14) and female lambs (G2, n = 7), during the summer under tropical conditions, in southern Mexico were analyzed. Different physiological variables and skin temperatures (ST) of the ewes were recorded. Breathing frequency (BF) values were similar between groups at 116.73 ± 33.598 bpm (G1) and 113.661 ± 34.515 bpm (G2) (p > 0.05). In the case of skin elasticity (SE), there were no significant differences between the time of day and the age of the ewes (p > 0.05). Significant differences were observed between groups for BF, rectal temperature (RT), and heart rate (HR) values (p < 0.05). All ST values, for both groups, were significantly higher during the afternoon (p < 0.001). In general, all Blackbelly adult ewes and female lambs during the summer present severe heat stress conditions as a result of an increase in physiological constants and ST. It is concluded that all ewes thermoregulate body temperature by modifying different physiological variables to counteract the effect of heat stress.

The aim of this study was to evaluate the intensity of the annual sexual behavior (SB) of Boer bucks under tropical conditions in southern Mexico. For one year, 16 extensively grazing males were evaluated for SB individually with estrogenized goats. From the beginning of the experiment and every 30 days, body weight (BW), body condition (BC), testicular circumference (TC), odor intensity (OI), and SB (nudging, ano-genital sniffing, flehmen, mounting attempts, mounts with intromission, and self-urination) were recorded. The bucks showed more intense SB during the months of November to May than during the months of June to October (p < 0.05). Greater frequencies were found for nudging, ano-genital sniffing, mounting attempts, and self-urination in the months of November to May (p < 0.001). BW was lower during the months of January to August than in the months of September to December (p < 0.05). On the other hand, TC increased from October to December (p < 0.05). Similarly, the OI in males varied over time (time effect; p < 0.001). In fact, an increased odor was found from October to December. The conclusions are that breed male goats from the tropics of Guerrero have a more intense SB during the months of November to May, but TC, OI, BW, and BC correspond to the time of the year when forage availability is the greatest.

J. Anim. Behav. Biometeorol., vol.11, n1, e2023001, 2023

Objective. To determine whether Blackbelly ewes are affected by heat stress (HS) during the summer in a tropical climate. Materials and methods. In this experiment, 21 female ewes were divided into two treatments (T1=7 female lambs and T2=14 multiparous ewes) to evaluate the effect of HS through the temperature and humidity index (THI), physiological, and hematological variables. Results. In the experiment, a THI between 77 and 88 U was found. Likewise, respiratory rate (RR) was higher in T2 in the afternoon (117 bpm) than in the morning (114 bpm) (p<0.05). Also, rectal temperature (RT) was found to be higher in T1 in the afternoon (39.3°C) than in the morning (38.9°C) (p<0.05). Finally, it was found that the heart rate (HR) was higher at T2 during the afternoon (p<0.05). The hematocrit (HCT) and hemoglobin (HB) variables were similar between treatments during the study, but there were differences between samples two to seven (higher concentrations) compared to sample 13 (lowest concentration) (p<0.001). Finally, the potential of the Hydrogen variable (pH) showed variations, being higher in samplings three and six, and lowest values in samples four, five, seven, and twelve (p<0.001). Conclusions. Blackbelly ewes showed severe HS during the summer in the tropics of Guerrero.