Early mother–young relationship and feeding behaviour of lambs are unaffected by low pasture allowance until the beginning of the last third of gestation in single-bearing ewes

Abstract

Nutrition during gestation influences ewes’ bodyweight (BW), the bond with their lamb, milk yield and lamb development, and thus feeding behaviour of lambs during postnatal rearing. The aim of this study was to determine if the level of native pasture allowance from before conception until the beginning of the last third of gestation of single-bearing ewes influences the ewe–lamb relationship at birth and the feeding behaviour of lambs during postnatal rearing. A second aim was to determine whether the nutritional treatments affect ewes’ milk yield and their lambs’ bodyweight. Eleven multiparous Corriedale ewes grazed a high pasture allowance [10–12 kg of dry matter (DM)/100 kg of BW/day; HPA treatment], and another 11 grazed a low pasture allowance (5–8 kg of DM/100 kg of BW/day; LPA treatment) for 145 days beginning 40 days before conception. After the end of this treatment all ewes grazed on Festuca arundinacea and received rice bran and crude glycerine until 3 days before birth. Ewes’ BW was recorded monthly before and during gestation. Latency from parturition until the ewe licked her lamb, latency for lamb to stand up and suckle were recorded, and Maternal Behaviour Score was determined 12–24 h after birth. All the variables recorded during postpartum were determined approximately every 30 days. Grazing, ruminating and suckling events of the lambs were recorded from Day 23 until 142 days of age. Milk yield was determined from 32 until 140 days after lambing. Lambs’ BW was recorded from birth until 140 days of age. On Day 41 the BW change tended to be greater in HPA ewes than in LPA ewes, and on Days 79 and 105 it was greater in HPA ewes than LPA ewes (P = 0.006 and P = 0.005 respectively). Treatments did not affect the behaviours at birth of ewes and lambs, milk yield, ruminating and suckling events of lambs, ewes’ and lambs’ BW. The lambs from HPA ewes tended to present a greater frequency of grazing than the LPA lambs. Different levels of native pasture allowances from before conception until the last third of gestation in single-bearing ewes, followed by an increase in nutrient supply, did not affect ewe–lamb behaviours at birth, milk yield, lambs’ growth, and their feeding behaviours during rearing.