The effects of heat stress on the development of the foetal lamb

Hopkins, PS; Nolan, Colleen J.; Pepper, P.M.

doi:10.1071/ar9800763

Cited by 26 publications

(30 citation statements)

References 7 publications

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“…Moule 1954 found a total loss between birth and marking of 36·4 % of lambs born), and poor milk production of ewes-300-500 ml/day (Stephenson, unpublished data). Hopkins et al (1980) have described the survival of lambs in relation to the rectal temperatures and respiratory rates of their dams during exposure to tropical summer conditions. Macfarlane et al (1956Macfarlane et al ( , 1958 have described the water intakes of non-lactating sheep under semi-arid conditions.…”

Section: Introductionmentioning

confidence: 99%

Effects of Heat Stress on the Lactation Performance of Ewes Accustomed to Tropical Conditions and the Total Fluid Intake of Their Lambs

Stephenson¹,

Hooley²,

Findlay³

et al. 1980

Aust. Jnl. Of Bio. Sci.

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The impact of heat stress on the feed intake, milk production, water intake and urine output of undernourished lactating ewes and on the growth rate and water intake of their lambs was measured both in a climate chamber and during exposure to natural high ambient temperature conditions. Similar liveweight increases occurred in both stressed and unstressed lambs. Feed intake was depressed in heat-stressed ewes in the climate chamber but not under natural heat-stress conditions. During the first and second weeks of lactation calculated milk yield (200-500 mljday) and composition were unaffected by heat stress per se. However, undernutrition due to the poor quality roughage offered apparently depressed milk production of all ewes. Increased water intake (27 %) and plasma prolactin concentrations (220 %) were recorded in heat-stressed ewes, but daily urine output (27-36 mljkg body wt) was unaffected. No relationship between prolactin concentrations, milk production and antidiuretic activity was obvious. At the age of 5-6 weeks water intake accounted for 67 % (500 mljday) and 80 % (1000 mljday) of total fluid intake (water plus milk) of unstressed and heat-stressed lambs respectively. These data indicate the importance of making water freely available to lambs subjected to extensive grazing systems of tropical regions.

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Section: Introductionmentioning

confidence: 99%

Effects of Heat Stress on the Lactation Performance of Ewes Accustomed to Tropical Conditions and the Total Fluid Intake of Their Lambs

Stephenson¹,

Hooley²,

Findlay³

et al. 1980

Aust. Jnl. Of Bio. Sci.

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“…Birth weight and survival of neonatal lambs was improved when shade was provided during late pregnancy (Hopkins et al, 1980). This suggests that heat stress has an effect on the uterine environment, substantially reduces the total embryo cell number and placentome size resulting in smaller size of lambs.…”

Section: Effect On Growth Performancesmentioning

confidence: 77%

Global Warming and Livestock in Dry Areas: Expected Impacts, Adaptation and Mitigation

Salem¹,

Rekik²,

Lassoued³

et al. 2011

Climate Change - Socioeconomic Effects

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“…In studies conducted in temperature controlled rooms (elevated vs. winter temperatures), Hopkins et al (1980) found that induced heat stress had no detrimental effect on the mean daily feed intake and live weight of sheep. In their experiment, elevated temperatures were maintained for 16-17 h each day.…”

Section: Discussionmentioning

confidence: 99%

“…In this regard, Stephenson et al (1984) found that the birth weight of lambs born to ewes with access to shade was higher than that of lambs born to ewes with no access to shade. In the tropical conditions of Queensland (Australia) Hopkins et al (1980) found that chronic heat stress during pregnancy was associated with foetal growth retardation, resulting in a decline in lamb birth weight. The physiological mechanisms responsible for negatively affecting lamb birth weights following maternal heat stress are obscure (Alexander, 1974).…”

Section: Discussionmentioning

confidence: 99%

“…Heat stress reduces feed-intake, growth and reproduction. Studies conducted in Queensland (Australia) indicated that birth weight and survival of neonatal lambs was improved when shade was provided during late pregnancy (Hopkins et al, 1980). This suggests that heat stress has an effect on the uterine environment, causing lambs to be smaller at birth and to have a lower viability.…”

Section: Introductionmentioning

confidence: 97%

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The effects of shade and shearing date on the production of Merino sheep in the Swartland region of South Africa

Cloete¹,

Muller²,

Durand³

2000

SA J. An. Sci.

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A total of 497 Merino ewes were allocated to one of four experimental groups for the period 1996 to 1998. The treatments were designed to provide data on the effect of shade during an autumn lambing season and the effect of shearing prior to joining in September or prior to lambing in February. Dietary intake in shaded and control paddocks was similar, but animals in shaded paddocks consumed less water than those in control paddocks. Lambs born in shaded paddocks tended to be heavier at birth than those born in control paddocks. Survival of lambs was unaffected by the provision of shade, but lambs born in shaded paddocks were 3.8 % heavier at weaning than contemporaries born in control paddocks. Lambs born to ewes that were shorn prior to lambing tended to be lighter than those from ewes shorn prior to joining. Lamb survival prior to weaning tended to be higher in lambs born to ewes shorn prior to lambing than in those shorn prior to joining. Shearing of ewes prior to lambing had a beneficial effect on lamb survival during 1997, when the survival of progeny of ewes shorn prior to joining was low. Annual lamb survival data obtained in the present experiment were combined with that from two previous experiments conducted at the same site. The response in lamb survival of the progeny of ewes shorn prior to lambing depended on the average lamb survival observed in the control group. Multiple-born progeny of ewes shorn prior to lambing grew faster to lamb marking than contemporaries born to ewes shorn prior to joining. No difference was detected in single lambs. The clean fleece weight of ewes shorn prior to lambing was heavier than that of contemporaries shorn prior to joining. Similar benefits were found for staple strength and the frequency of mid-staple breaks. It was concluded that the shearing of ewes prior to lambing might be advantageous under certain conditions, particularly when lamb survival is likely to be low.

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The effects of heat stress on the development of the foetal lamb

Cited by 26 publications

References 7 publications

Effects of Heat Stress on the Lactation Performance of Ewes Accustomed to Tropical Conditions and the Total Fluid Intake of Their Lambs

Effects of Heat Stress on the Lactation Performance of Ewes Accustomed to Tropical Conditions and the Total Fluid Intake of Their Lambs

Global Warming and Livestock in Dry Areas: Expected Impacts, Adaptation and Mitigation

The effects of shade and shearing date on the production of Merino sheep in the Swartland region of South Africa

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