Habituation to cold in four breeds of sheep

Slee, J.; Forster, Janet

doi:10.1016/0306-4565(83)90020-7

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…t h i s r e s P e cv ariation in the responses of sheep exposed A n e a r ' e r P u a P er s h°w e d * a t i n b r^ s h e e P to cold and heat (Sykes and Slee, 1969a: w 4 e r e s m a l l e r "; han o u t b r e d s h e e P a t 2 6 w e e k s Doney and Slee, 1972;Slee, 1974 and1985; °f a 8 e b u t h a d s i m i l a r 8 r o w t h r a t e s w h e n Slee and Forster, 1983). t h i s r e s P e cv ariation in the responses of sheep exposed A n e a r ' e r P u a P er s h°w e d * a t i n b r^ s h e e P to cold and heat (Sykes and Slee, 1969a: w 4 e r e s m a l l e r "; han o u t b r e d s h e e P a t 2 6 w e e k s Doney and Slee, 1972;Slee, 1974 and1985; °f a 8 e b u t h a d s i m i l a r 8 r o w t h r a t e s w h e n Slee and Forster, 1983).…”

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A comparison of inbred and outbred sheep on two planes of nutrition 2. Responses to acute cold and heat exposure

1988

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Four groups each of 14 sheep aged 11 to 13 months comprising outbred (O) and inbred (I, inbreeding coefficient 0·37 or 0·5) sheep reared on either a low plane (L, maintenance) or on a high plane (H, ad libitum) of nutrition from the age of 6 months were exposed first to acute cold and 1 week later to heat. Exposures in climate chambers ended for each sheep when rectal temperature decreased to 36°C (in the cold) or increased to 42·5°C (in the heat) subject to a limit of 8 h. Throughout the experiment, sheep were kept in matched quartets comprising one sheep of each type.The average cold resistance times (min) were 161, 267, 348 and 381 for the LI, LO, HI and HO groups respectively, showing a significant effect of both inbreeding and plane of nutrition (P < 0·01). Five sheep in the HO group lasted the full 8 h in the cold chamber with little or no reduction in rectal temperature. Skin temperature at the mid side was significantly higher in L than in H sheep throughout cold exposure, but there was no effect of inbreeding.Respiration rates were much higher before and during cold exposure in the H sheep, but there was no effect of inbreeding.The residual correlation of cold resistance with live weight was 0·58, but differences in live weight do not explain all the differences in cold resistance and particularly do not explain the rapid decrease in rectal temperature of the LI sheep. It was concluded that under cold exposure a high level of nutrition was able to compensate partly for the disadvantages of inbreeding, and that outbreeding was able to compensate partly for the adverse effects of poor nutrition.With heat exposure, there were no significant differences among the four groups in heat tolerance time, but within the 1st h, H sheep had slightly higher rectal temperatures and much higher respiration rates than L sheep. Inbreeding affected only the time taken to reach a respiration rate > 200 per min, which was longer in I (131 min) than in O sheep (113 min) and longer in L (149 min) than in H animals (96 min).

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A comparison of inbred and outbred sheep on two planes of nutrition 2. Responses to acute cold and heat exposure

1988

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The significance of interactions in practical sheep breeding in northern Europe

Steane

1983

Livestock Production Science

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Thermoregulation in neonatal ruminants

Rowan

1992

BSAP Occas. Publ.

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This review is directed to thermoregulation in ruminants relative to weather and husbandry conditions of the United Kingdom in which the principal ruminant species are cattle and sheep. The main thermoregulatory demands for neonates, but not necessarily for older animals, are posed by cold rather than heat. Thermoregulation is critical to the survival of neonatal ruminants. On many farms, neonatal deaths are, for example, 20% of lambs born. Neonatal ruminants are precocial compared with many altrical neonatal mammals and have well developed thermoregulation which allows them to maintain homeothermy in many environments. However, at birth the neonatal ruminant moves from a very stable thermal environment, of similar temperature to its core body temperature, to a variable thermal environment which is 10 to 50°C colder than its core temperature. At birth the coat is wet and energy losses can be very high. To maintain homeothermy, heat production can usually be increased 3- to 5-fold above resting heat production. However, there are only limited quantities of tissue substrates available for this and the early intake of sufficient colostrum by the newborn is essential to continued heat production and survival. Nutrition in early and late pregnancy also affects the viability of, at least, young lambs: placental insufficiency may cause chronic prenatal hypoglycaemia and hypoxaemia which, postnatally, inhibits spontaneous respiration and restricts heat production. In calves, dystocia may cause acidosis and decreased heat production.The principal thermoregulatory mechanisms and some factors which affect their efficiency in newborn calves and lambs are presented, with consideration of the limitations of lower critical temperatures.

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Habituation to cold in four breeds of sheep

Cited by 4 publications

References 7 publications

A comparison of inbred and outbred sheep on two planes of nutrition 2. Responses to acute cold and heat exposure

A comparison of inbred and outbred sheep on two planes of nutrition 2. Responses to acute cold and heat exposure

The significance of interactions in practical sheep breeding in northern Europe

Thermoregulation in neonatal ruminants

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