HEAT STORAGE IN RELATION TO SOME COAT CHARACTERISTICS IN SHEEP AND GOATS UNDER DESERT CONDITIONS | ||||
| Journal of Animal and Poultry Production | ||||
| Article 3, Volume 30, Issue 1, January 2005, Page 129-141 PDF (509.83 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jappmu.2005.237949 | ||||
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| Author | ||||
| W. H. Abd-ElGhany, | ||||
| Wool Production And Technology Department, Desert Research Center, Mataria, Cairo, Egypt. | ||||
| Abstract | ||||
| To define the heat storage which may be considered as an important factor in adaptability for sheep and goats under desert conditions as well as to spotlight the coat contribution in thermoregulatory responses in summer, 20 Barki rams and 20 Baladi bucks were used in this study from the Desert Research Center flock raised at Maryout Research Station. Animals were kept in open pens exposing to direct sun light. Staple length STL, fibre diameter FD, and different coarse medullated fibres percentage (C1-C2-C3) % were measured. Rectal temperature RT, skin temperature ST, ear temperature ET, coat temperature CT and respiration rate RR were recorded. Plasma thyroxine T4, triiodothyronine T3 and cortisol levels were determined. Rams recorded higher (P>0.01) heat storage values (x=677.815kj) than bucks (x=496.38kj). Live body weights BWs of higher heat storage animals (HHS) were decreased than BWs of low heat storage animals (LHS). The heat storage / body weight (H/B ratio) of HHS groups were higher (P>0.05) than LHS groups of both the two species. Rams of HHS group were lower (P>0.05) in H/B ratio (16.97kj/kg) than the same group in bucks (18.09kj/kg). The HHS groups of rams and bucks had lower values of RT, ST, ET and RR than LHS groups. Rams and bucks of HHS groups recorded an increase in CT compared to LHS groups at 2 p.m. The HHS group of bucks tended to decrease in RT, ST, CT and RR values in comparison with the same group of rams. On the other hand, ET of HHS bucks group was higher than the same group of rams. Moreover, RR values of HHS groups were lower (P>0.05) than LHS groups in the two species which may indicate that the HHS animals appeared to be more able to conserve water by having lower respiratory rate than those of LHS animals under desert conditions in summer. The HHS group of bucks had lower (P>0.05) RR than the same group in rams, which means that bucks of HHS group could more efficiently regulate their water turn over rate than that of rams. Rams and bucks of the HHS groups recorded lower (P>0.05) plasma concentrations of T3 and cortisol than those animals of LHS groups. Plasma T3 concentrations of both HHS and LHS groups in bucks were higher (P>0.01) than those in rams, whereas the former groups of bucks had slightly lower concentrations for each of plasma T4 and cortisol than in rams, which may indicate that rams tended to reduce plasma T3 levels more than bucks in order to likely reduce relatively heat production. The animals of HHS groups had more of coarse medullated fibres percentage for type (C1), fibre diameter (FD) and staple length (STL); whereas they recorded less coarse medullated fibres percentage for type (C3) compared to those of LHS animals in the two species. According to their insulative properties, coarse medullated fibres (C1%) which existed in animals of HHS groups could cause values tendency in their RT, ST, ET, RR, T3 and cortisol leading to more regulated elevation of their core body temperature than animals of LHS groups. It is believed that both the two fleeces of higher heat storage groups of rams and bucks had staple length, fibre diameter and coarse medullated fibres enough to regulate their bodies temperatures than those had lower heat storage under solar radiation during hot summer in desert. | ||||
| Keywords | ||||
| Sheep; Goats; Heat storage; Thermoregulation; Physiological parameters; Blood constituents; Wool; Hair | ||||
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