Maternal Heat Stress and Its Effects on Calves

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Elmi Dahir I., Muse Mohamud M., Khalif Mohamud M., Konca Y.

15.Ulusal Zootekni Öğrenci Kongresi , Adana, Turkey, 9 - 11 May 2022, vol.1, pp.96-97

  • Publication Type: Conference Paper / Summary Text
  • Volume: 1
  • City: Adana
  • Country: Turkey
  • Page Numbers: pp.96-97
  • Erciyes University Affiliated: Yes


Heat stress (HS) is a condition characterized by high ambient temperature and humidity. Twothirds of the calves' development takes place in the last two months of pregnancy; during this rapid growth period of fetus, the stress of the mothers negatively affects the offspring. Feed consumption, milk production, reproduction, udder development, morbidity and mortality rate and immunity are adversely affected in dairy cows exposed to heat stress and economic loses. Low birth weight (about 9%) in calves and low milk yield in the next lactations are obtained in dairy cows exposed to stress in the last period of pregnancy. In heat stress condition, the blood flow to the placenta and nutrients transfers to embryo decrease, also, placental hormones circulation decrease in the mothers exposed to heat stress in the late period of pregnancy, and the cause give birth earlier. Calves with low birth weight can only compensate for the weight loss in a long period of one year. Reduced birth weight of calves due to in utero stress can be attributed fetal hyperthermia and impaired placental function and so, a shorter gestation period. In-utero heat stressed calves have lower plasma concentrations of insulin, insulinlike growth factor-I, prolactin and but no difference in glucose, or β-hydroxybutyrate (BHBA) and non-esterified fatty acid (NEFA) plasma concentrations.. Normally, postpartum calves are not exposed to metabolic stress due to the lack of production, and therefore they are less affected by environmental heat stress than adult animals. However, studies have shown that calves exposed to postnatal heat stress also have a decline in growth, an increase in morbidity and death rates in calves. For a successful calf production, in the prenatal and postnatal periods calves must be protected from heat stress.