Post Weaning Feeding Management and Performance of Merino Ewes Grazing on Natural and Improved Pastures at Mating Season

Abstract

In the uruguayan Basalt region, the reproductive performance of 300 Merino ewes and the effect of 3 post-weaning feeding managements (PWFM: I: 1.2 cm height of available forage and 16 ewes/ha; II: 2.03 cm height of available forage and 5 ewes/ha; III: 2.5cm height of available forage and 1 ewe/ha) as well as 2 feeding levels before and during the breeding season (FLM: native pastures: green DM/ha: 883kg, CP: 114g/kg DM, NDF: 781g/kg DM and improved pastures: DM /ha: 1270kg, CP: 194g/kg DM, NDF: 598g/kg DM) were studied with a factorial arrangement of treatments. The PWFM extended for 70 days, ewes were mated in the period from 13/4/96 to 13/5/96 and FLM were applied for 30 days, starting 15 days before beginning of breeding. There were not differences on the ovulation rate (P>0.05); however, the P values might indicate some effect of the treatments. The number of born lambs/ewe served increased with the ovulation rate because the higher number of ovulations balanced their less viability, individually considered. Actually, the number of born lambs/ewe served was higher with animals coming from PWFM III (1.18, 1.11 and 0.96, PWFM III, II and I, respectively; P = 0.02) and with the animals grazing on improved pastures at mating period (1.13 and 1.03, improved pastures and natural pastures, respectively; P = 0.10), were those which showed slight higher ovulation rate.

Desempenho de ovinos recebendo suplementos ou mantidos exclusivamente em pastagem de azevém (Lolium multiflorum Lam.)

“…O uso exclusivo da pastagem de azevém foi adequado para o desenvolvimento produtivo de ovelhas, com idade de 1 a 3 anos e cria ao pé. Bianchi et al (2001) observaram redução no peso médio do pós-parto ao desmame em ovelhas de 3 anos com cria em campo nativo com suplementado ou não com 300 g de cevada/ovelha/dia. Na média do período total de pastejo, o ganho médio diário das cordeiras foi semelhante (P>0,05), de 0,177; 0,201; e 0,216 kg para animais sob suplementação com grão de milho, farelo de soja ou sem suplementação, respectivamente.…”

Onset of reproductive activity of white and natural colored corriedale ewe lambs

“…According to Ribeiro et al (2003), there exists a strong relationship between body condition at mating with pregnancy rate, recommending a higher nutrient supply before and during the breeding season. This would lead to increment in pregnancy rates and prolificness, given the higher ovulation rate of supplemented sheep (BIANCHI et al, 2001). …”