The aim of this study was to evaluate the physiological responses of adult male Red Sokoto goats (n = 10; indigenous to the Guinea Savannah climate) and Sahel goats (n = 10; indigenous to the Sahel climate) at the peak of the cold-dry (CDS), hot-dry (HDS) and rainy seasons prevailing in the Guinea Savannah zone of Nigeria. Results revealed that Red Sokoto goats had significantly higher rectal temperature (RT), PCV, red blood cell (RBC), Hb, thyroxin (T 4 ), but lower respiratory rate (RR) and total leucocyte count (TLC) than Sahel goats during the CDS. Comparison within breeds for the three seasons showed that both breeds exhibited the highest (P < .05) PR, RT, neutrophil-lymphocyte ratio (N:L), but lower mean corpuscular volume and triiodothyronine (T 3 ) during the HDS. In addition, Red Sokoto goats showed higher (P < .05) RR and T 4 , but lower RBC, Hb, lymphocyte counts and T 3 :T 4 . However, Sahel goats exhibited higher (P < .05) PCV, RBC, erythrocyte osmotic fragility, but lower circulating T 4 . It was concluded that the cold and hot seasons exerted different physiological effects on the two breeds of goats with marked variation in RT, composition of blood cellular components, thyroid physiology and erythrocyte membrane integrity. ARTICLE HISTORY

ABSTRACT:The current study was aimed at evaluating the effect of heat stress (during the hot-dry period) on some physiological variables, haematology and erythrocyte osmotic fragility (EOF) in bucks, pregnant (single and twin) and lactating Red Sokoto (RS) goats. Forty apparently healthy adult goats were used for the study and were allotted to four groups [bucks (n = 10), pregnant (n = 10) dry (n = 10), and lactating (n = 10) does]. The pregnant goats were further re-grouped according to number of foetuses (single foetus, n = 5 and twins, n = 5). The temperature-humidity index and physiological variables measured were significantly higher in the afternoon compared to morning hours. Pregnant does had higher respiratory and pulse rates than the dry does, but no significant change (P > 0.05) in rectal temperature was observed between groups. On the basis of sex, bucks had lower (P < 0.05) mean corpuscular volume (MCV) than other groups, in addition to having higher (P < 0.01) mean corpuscular haemoglobin (MCH) and total leucocyte counts than dry does. Pregnant does exhibited significantly lower (P < 0.05) packed cell volume, but significantly higher (P < 0.05) MCH and mean corpuscular haemoglobin concentrations (MCHC) than lactating does. Does with a single foetus had significantly lower (P < 0.05) MCV, but higher MCHC than does with twin pregnancies. Using EOF as a biomarker of oxidative stress, erythrocytes of bucks were significantly more resistant to hypotonic haemolysis than those of dry, pregnant and lactating does, with no significant difference in EOF between does of different groups. The erythrocytes of single and twin pregnancies showed similar haemolysis pattern. In conclusion, sex, lactation, and the number of foetuses carried by pregnant does significantly influences physiological and haematological variables in RS goats during the hot-dry season. Also, during heat stress, the changes in physiological variables seem to enhance favourable adaptation by preventing an increase in rectal temperature even in twin pregnancies.

No abstract

No abstract

Abstract. The influences of breed, sex and age on seasonal changes in haematological variables of kids (1-4 months old) belonging to Red Sokoto (n = 60) and Sahel (n = 60) goats were studied at the peaks of the cold-dry, hot-dry and rainy seasons in a West Africa Guinea savanna climate. The results showed that, during the hot-dry season, Sahel goat kids had significantly higher (P < 0.05) packed cell volume (PCV) and red blood cell (RBC) count but lower (P < 0.05) mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and total leucocyte count than Red Sokoto kids. Similarly, younger kids of both breed had significantly higher (P < 0.05) PCV and RBC but lower MCV, MCH and MCHC compared with the older kids during the hot-dry season. Younger kids (1-2 months) of both breeds exhibited significantly (P < 0.05) high PCV and RBC but low MCH and MCHC during the hot-dry season as compared with the cold-dry and rainy seasons, with the magnitude of the change being greater in Sahel kids. More remarkable seasonal fluctuations in haematological parameters were observed in buck kids than doe kids of both breeds. Multivariate analysis revealed a clear distinction between the change in haematological parameters during the cold-dry as compared with the hot-dry and rainy seasons, with MCV having the strongest discriminating power (0.91 * ). In conclusion, breed, age and sex variations in haematological variables of goats were more pronounced in the hot-dry season, during which the seasonal changes were more dramatic in kids of Sahel goats, as well as in younger and male kids of both breeds. These findings may be useful in the management of tropical goat kids in different seasons.