Maternal nutrition and antioxidant supplementation: Effects on mother-young behaviors in a Patagonian sheep extensive grazing system

Undernourishment is a frequent condition in sheep pregnancies under extensive systems, since most of the pregnancies occur when the prairie has the lowest forage allowance. Underfed sheep pregnancies are associated with maternal-fetal oxidative stress, low birth weight and deteriorated ewe-lamb bond, which negatively affects the probability of postnatal survival. The aims of the present study were to determine if daily supplementation of underfed single-bearing grazing ewes during pregnancy (starting at Day 44) with concentrate food and/or vitamins C and E: 1) improves maternal body weight and body condition, and increases udder size and skin temperature of the udder at parturition, 2) increases lamb' body weight and both surface and rectal temperatures, and 3) modifies ewe-lamb behavior at lambing. A complementary goal was to determine if those effects differ between male and female lambs. The experiment was carried out under field conditions representative of Chilean Patagonia. Maternal supplementation with concentrate resulted in enhanced ewes' body weight (59.4 +/- 0.9 kg vs 55.1 +/- 0.9 kg; P = 0.0007) and body condition during gestation (2.21 +/- 0.05 vs 1.69 +/- 0.05; P<0.0001), enhanced udder volume (P<0.0001), increased newborn lambs' body weight (5.0 +/- 0.1 kg vs 4.7 +/- 0.1 kg P = 0.03), and strengthened maternal bonding with its lamb during a handling test, without effects on lamb' rectal temperature. Supplementation with vitamins C and E, did not produce a clear effect on the studied variables, and did not improve the response to supplementation with concentrate. In conclusion, improvement of nutritional plane in underfed single-bearing ewes it is not only relevant to improve the pregnancy outcomes, but also to ensure a better ewe-lamb bonding, which may improve lamb's survival and performance during lactation.