Effects of late gestational protein restriction on birth weight, growth rate and plasma concentrations of IGF1, insulin, urea and glucose in suckling lambs

In this study the effects of late gestational protein restriction (LGPR) on birth weight، growth rate and plasma concentrations of insulin-like growth factor-1 (IGF-I)، insulin، urea and glucose in subsequent sucking lambs was investigated. Forty eight singe-bearing ewes from indigenous Lori-Bakhtiary sheep were fed iso-energetic diets either with 12. 5% (Control; n=24) or 8. 6% (Restricted; n=24) crude protein from day 105 until parturition. Ewes were fed ad-libitum after parturition. Lambs birth weight، morphological characteristics (head size، body length and height)، and growth rate and feed conversion rate until age of one-month were recorded. Blood samples were taken at birth، 4، 10 and 15 days of age and were analyzed for IGF-I، insulin and urea and glucose. LGPR decreased lambs birth weight (p<0. 05) but had no significant on morphological characteristics (p>0. 05). Glucose plasma concentrations were the lowest on birth day (p<0. 05) and increased with age. Insulin values did not significantly differ between control and restricted lambs (0. 97vs. 1. 20µg/dl). IGF-I values were not affected by LGPR with 204 and 213 ng/ml for restricted and control lambs respectively. Urea concentrations were 45 and 43 mg/dl for control and restricted lambs respectively. Urea values at age 15 were significantly lower in restricted (29mg/dl) in comparison to control lambs (41mg/dl). In conclusion LGPR born lambs showed lower birth weight and lower plasma urea concentration which might be a sign of better protein metabolism in subsequent suckling lambs.