Influence of sex, reproductive status and foetal number on erythrocyte osmotic fragility, haematological and physiologic parameters in goats during the hot-dry season

Abstract

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.

Influence of seasonal changes on physiological variables, haematology and serum thyroid hormones profile in male Red Sokoto and Sahel goats

“…In the present study, the increase in EOF during the HDS compared to the CDS and RAS in Sahel goats may be due to heat stress (Brzezinska-Slebodzinska 2001;Habibu et al 2014). Heat stress indicated by increase in body temperature during the HDS may have enhanced the production of free radicals and subsequently, occurrence of lipid peroxidation.…”

“…The PR was significantly higher in Sahel than Red Sokoto goats during the HDS, while the HDS was characterized by higher PR compared to the CDS and RAS. This may suggest increased rate of blood flow to the periphery and thus improved heat loss via sensible and insensible means (Marai et al 2007;Habibu et al 2014). In the Red Sokoto goats, RT was higher during the CDS and HDS compared to RAS.…”

“…Heat stress indicated by increase in body temperature during the HDS may have enhanced the production of free radicals and subsequently, occurrence of lipid peroxidation. The ultimate consequence is an increase in the fragility of the erythrocytes membrane and thus, elevation in EOF (Brzezinska-Slebodzinska 2001; Habibu et al 2014;Yaqub et al 2014). Similarly, higher EOF has been reported in animals exposed to transport stress compared to those in which the effect of transport stress was ameliorated using antioxidant ).…”

Phenotypic drift in osmotic fragility of Sahel goat erythrocytes associated with variability of median fragility

“…(Oyewale, 1991;Oyewale, 1993;Oyewale et al, 1997) and Sahel goats (Igbokwe & Igbokwe, 2015), 8 g/L in Red Sokoto (RS) goats (Habibu et al, 2014), and 6-8 g/L in RS goats during rest and after loading and transportation stress (Minka & Ayo, 2010). Some of these MEF values were read from published fragiligrams where there was no haemolysis in isotonic saline (Oyewale, 1991;Oyewale, 1993;Oyewale et al, 1997;Igbokwe & Igbokwe, 2015) in contrast to where there was isotonic haemolysis of about 20% (Habibu et al, 2014) or 20-40% (Minka & Ayo, 2010). An isotonic haemolysis may be an artefact arising from using blood samples with extracellular haemoglobin due to in vitro or in vivo haemolysis as shown in the increase of the mean corpuscular haemoglobin concentration (MCHC) to 63.7 ± 2.8 g/dL (Minka & Ayo, 2010) from a lower reference mean (32.3-39.6 g/dL) for goats (Byers & Kramer, 2010).…”

“…Normal values of MEF in goats are not available apart from those estimated from fragiligrams in reports of some controlled experiments with disparities in data presentations (Oyewale, 1991;Oyewale, 1993;Oyewale et al, 1997;Minka & Ayo, 2010;Habibu et al, 2014;Igbokwe & Igbokwe, 2015). Phenotypic variations in EOF may exist in Sahel goat populations under physiological conditions as was previously reported with respect to erythrocyte glutathione concentrations (Igbokwe et al, 1998).…”