Effects of breed and sex on the adaptive profile of tropical goats

Abstract

This study was embarked upon to evaluate breed and sex effects on the thermo-physiology and blood parameters; predict heat stress index and appropriately classify Nigerian West African Dwarf (WAD) and Red Sokoto (RS) goats in a 2 x 2 factorial experiment involving twenty four goats. WAD goats had higher rectal temperature (38.93±0.10 versus 38.59±0.10) and pulse rate (54.78±0.24 vs. 53.67±0.24) compared to their RS counterparts. However, there was no significant difference in heat stress index between WAD and RS goats. Based on thermo-physiological parameters, male goats appeared to be more stressed. There was no significant Breed * Sex interaction effect on thermo-physiological traits. The results of haematological and serum biochemical and hormonal indices of goats also indicated that WAD goats appeared to be more stressed. The male goats had higher Cortisol (58.00±4.88 versus 37.67±4.88) and lower Thyroxine (111.50±8.32 vs. 141.18±8.32) levels. There was no significant Breed * Sex interaction effect on haematological indices. While male and female WAD goats were similar, female RS goats had higher value of TSH (1.20±0.21) than their male counterparts (0.57±0.21). The Artificial Neural Network algorithm revealed that respiratory rate, cortisol, pulse rate and WBC had more influence on heat stress prediction in goats compared to breed, sex and other haematological, serum biochemical and hormonal parameters. Haemoglobin, white blood cells, rectal temperature and pulse rate were sufficient to correctly assign WAD and RS goats to their appropriate breed. The present information may aid breed characterization and conservation of WAD and RS goats.   Keywords: Heat stress, blood markers, goats, prediction, tropics