Tracking growth performance and insulin response on four-month-old maternal heat-stressed lambs.

Poor growth performance and metabolic disorders are prevalent problems in lambs exposed to maternal heat stress, specifically during the last midthird of gestation. Columbia–Rambouillet crossbred lambs (n = 12) were immediately separated from their heat-stressed and non-stressed dam at lambing. The maternal heat stress exposure occurred during the last mid-third gestation and was for about 40 d (40 to 80 d). Lamb body weight (BW) was recorded daily for 4 mo. A glucose tolerance test was performed in mo 4 to evaluate glucose concentrations and insulin response. Maternal heat-stressed lamb (HS) presented reduced BW throughout the experimental time (P < 0.05) than maternal thermoneutral lamb (TN; CN = 12.69 ± 0.29 kg and HS = 9.89 ± 0.29 kg). Glucose concentrations were similar between environmental conditions (P > 0.05). Neither the insulin response presented a significance (P > 0.05) between those lambs exposed to HS and TN conditions during gestation. Although maternal exposure to HS can affect performance of the offspring throughout life, metabolic disorders associated with insulin resistance are not a problem at 4 mo. However, preliminary data showed that these same lambs at 8 mo old and 11 mo old show an irregular insulin response in maternal heat-stressed lambs that can persist throughout the life of the offspring. [ABSTRACT FROM AUTHOR]