Chronic heat stress and prenatal development in sheep: I. Conceptus growth and maternal plasma hormones and metabolites.

  title={Chronic heat stress and prenatal development in sheep: I. Conceptus growth and maternal plasma hormones and metabolites.},
  author={Alan W. Bell and Brian W. McBride and R. M. Slepetis and Richard J. Early and William B. Currie},
  journal={Journal of animal science},
  volume={67 12},
Pregnant ewes were chronically exposed to thermoneutral (TN; 20 degrees C, 30% relative humidity) or hot (H; 40 degrees C 9 h/d, 30 degrees C 15 h/d, 40% relative humidity) environments between d 64 and 136 to 141 of pregnancy. They were sampled for blood at 14-d intervals during this period for measurement of plasma metabolites and hormones, then slaughtered and dissected to measure conceptus weights, dimensions and fetal organ weights. Rectal temperatures of H ewes were elevated .3 to 1.0 C… 

Figures and Tables from this paper

Chronic heat stress and prenatal development in sheep: II. Placental cellularity and metabolism.

Aspects of placental protein and energy metabolism were examined in pregnant ewes subjected to either thermoneutral (TN, 18 to 20 degrees C, 30% humidity, n = 7) or hot (H, 30 to 40 degrees C, 40%

Altered arterial concentrations of placental hormones during maximal placental growth in a model of placental insufficiency.

It is demonstrated that chronic heat exposure lowers circulating placental hormone concentrations and highlights that intrauterine growth retardation (IUGR) may result primarily from placental trophoblast cell dysfunction, and secondarily from later reduced placental size.

Heat stress during mid-pregnancy in sheep and the consequences for placental and fetal growth

It was concluded that restricted placental growth in heat-treated eWes retarded fetal growth during late pregnancy even in the absence of heat treatment, and it is suggested that selection of ewes which can maintain normal rectal temperatures during periods of heat stress would produce lambs of normal birthweight in a hot climate.

Maternal endocrine and fetal metabolic responses to heat stress.

Results are consistent with the following hypothesis: heat stress stimulates the release of maternal antidiuretic hormone or oxytocin, which reduces uterine blood flow and causes a shift in fetal metabolism from anabolic to catabolic pathways; one fetus of heat-stressed twins is more severely affected than its litter mate.

Effect of late-gestation maternal heat stress on growth and immune function of dairy calves.

It is concluded that heat stress of the dam during the dry period compromises the fetal growth and immune function of offspring from birth through weaning.

Late-gestation heat stress abatement on performance and behavior of Holstein dairy cows.

It is confirmed that heat stress abatement in the late gestation period improves performance of dairy cows in subsequent lactation.

Lamb birthweight in sheep differently acclimatized to a hot environment

The physiological basis for the difference in fetal growth in ewes which respond differently to a hot climate has not been identified, but possible mechanisms are discussed.

PHYSIOLOGY SYMPOSIUM: Effects of heat stress during late gestation on the dam and its calf12.

Emerging evidence suggests that late-gestation heat stress alters the mammary gland microstructure of the heifers during the first lactation and exerts epigenetic alterations that might explain, in part, their impaired productivity.



Nutrition of the conceptus: aspects of its regulation

  • J. Bassett
  • Medicine
    The Proceedings of the Nutrition Society
  • 1986
Viewed simplistically, nutrition of the developing conceptus can be seen as an added cost on the nutrient requirements of the pregnant animal, but provision of adequate nutrients to support growth of the conceptus is clearly more complex and involves considerable adaptive responses on the part of the mother throughout gestation.

Repeated measurement: sensitive tests for experiments with few animals.

  • J. L. Gill
  • Mathematics, Medicine
    Journal of animal science
  • 1986
A method is given for comparing treatments in a way that permits sensitive tests, often when the number of animals per treatment is not more than five or six, and modifications for the procedure are given for the case of heterogeneous variances and covariances.