Prepartum grazing with oat pasture and its effect on mother-lamb behaviour at parturition [Poster].

Nutrition during gestation has an important role at time of parturition for both mother and offspring. The effect of different nutritional management during the last month of pregnancy on body condition (BCS), body weight (BW) and mother-lamb behaviour at parturition was evaluated. One hundred and forty multiparous Corriedale ewes gestating a single lamb were offered native pasture (7% crude protein (CP)) during the first four months of gestation and were assigned to two differential nutritional management during the last month of pregnancy: (1) ewes grazing oat pasture (14% CP) (GO, n=71); (2) ewes fed native pasture (GNP, n=69), regarding BW and BCS at the beginningof the treatment (49.1±0.7 vs 49.7±0.7 kg and 3.74±0.05 vs 3.77±0.05 GO and GNP respectively). At parturition BW and BCS were registered, as well as duration of labour, delivery assistance and Maternal Behaviour Score (MBS,range 1-5). In lambs, birth weight, Apgar test for newborns (score 0-10), and time elapsed to stand and suck was recorded. Data were analysed using PROC MIXED and GENMOD of SAS, (mean ± SEM; P?0.05). At parturition GO ewes had higher BW (56.7±0.8 vs 52.7±0.7 kg P?0.0001) and BCS (3.7±0.04 vs 3.4±0.06 P=0.0007) than GNP. Duration of labour was longer (32.5±4.7 vs 24.03 min, p?0.001) and percentage of delivery assistance was significantgreater (22.5 vs 4.3%) in GO group. Lambs from GO mothers were heavier (4.77±0.07 vs 4.28±0.09 kg, P=0.0037),and took longer to stand (36.4±4.2 vs 28.5±3.9 min, p?0.001) and suck (56.4±5.2 vs 51.5±4.9 min, P=0.0011) than GNP lambs. There was no effect on MBS or Apgar test. The increment in BW and BCS of GO animals resulted in heavier lambs, that led to longer time of labor and less vigor compared with lambs of GNP ewes. Higher percentage of birth assistance in GO ewes suggests that the benefit of a greater weight at birth can be exploited only if control of parturition is performed. However, grazing oat pasture should be an alternative to be used with twin bearing ewessince lambs are usually lighter and have less vigor than single ones