Oscillatory thermo-regulatory behavior of fecundity gene introgressed sheep in hot semi-arid region

Fecundity gene (FecB) introgression improves the prolificacy of sheep. However, it may adversely affect the adaptability of thermoregulatory behavior when it is introgressed in other than hot-humid regions because it is found in the sheep of the hot-humid region. Therefore, the present study was initiated to assess the oscillatory thermoregulatory behavior of FecB-introgressed sheep in a hot semi-arid region. The thermoregulatory behavior parameters (i.e., respiration rate [RT], heart rate [HR], rectal temperature [RT], and skin temperature [ST]) were recorded at a three-hour interval for continuous 24 hours in well-adapted sheep of the semi-arid region and in FecB-introgressed sheep of the same region during extreme climatic conditions (summer and winter). The cosinor analysis showed a daily circadian rhythm (P < 0.01) in RR, HR, and ST values, as well as similar significant (P < 0.01) differences in thermoregulatory behavior in both the sheep during the summer and winter. The rhythmic change of ambient temperature throughout the day influenced the thermoregulatory physiological behaviors of both well-adapted and FecB-introgressed sheep under semi-arid conditions. The nonsignificant (P > 0.05) difference in mesor, amplitude, and acrophase in RR, PR, RT, and ST among the breeds during summer and winter indicated that the FecB-introgressed sheep also use a similar adaptive strategy to cope with environmental extremes of the hot, semi-arid region like well-adapted sheep.