Pre- and post-partum feed supplementation to improve sheep productivity in small-holder farms in southern Chile

Two experiments were carried out to assess the effect of feed supplementation in ewes during the pre- and post-partum period and subsequent ewe-lamb growth rates and reproductive performance during their first breeding season. In the first experiment, 50 Romney Marsch ewes on one farm were used and half were supplemented for 50 days before and after lambing with 500 g dry matter of grassland silage/day, and half were not supplemented. In the second experiment, six small flocks of Criollo ewes belonging to Mapuche farmers were used. Three flocks (total 30 ewes) were supplemented with a commercial multinutrient block (molasses, urea and mineral salts) for 50 days before and after lambing. The other 3 flocks (total 45 ewes) were maintained without supplementation. In both experiments, ewe live weight, body condition score (BCS), lamb birth weight and the subsequent ewe-lamb growth rate and reproductive performance were evaluated. The birth weight of ewe-lambs born to the supplemented dams in Experiment 1 was not statistically different (P>0.05) from the control group (3.9 kg vs. 4.2 kg). There was, however, a significant improvement (P<0.05) in weaning weight (31.4 vs. 27.6 kg), BCS, age at onset of ewe-lamb luteal activity assessed by progesterone measurements (171.8 vs. 194.9 days); and percentage of ewe-lambs showing oestrus activity at the end of the first breeding season (50 vs. 30%). There were no significant differences between groups for lamb birth weight in Experiment II (4.5 vs. 4.3 kg; P>0.05). However, differences (P<0.05) were found between ewe-lambs born to the supplemented dams and non-supplemented dams on weaning weight (21.8 vs. 17.2 kg), BCS, the age at onset of luteal activity (269 vs. 290 days) and pregnancy rate at the end of the first breeding season (55.6 vs. 30%). The results indicates that pre- and post-partum supplementation of ewes can improve ewe-lamb performance within their first reproductive season. (author). 19 refs, 4 figs, 3 tabs