164 The effect of grass silage compared to whole crop wheat silage on colostrum yield, lamb birth weight and ewe performance during late gestation

Abstract

Abstract Number of lambs born is a key factor influencing profitability of seasonal sheep meat production systems and a key driver of nutrient requirements. Energy and nutrient requirements to support foetal development, mammogenesis and lactogensis increase in the final eight weeks of ovine gestation. A 3 × 2 factorial design experiment involving 90 twin bearing ewes was conducted during the final eight weeks of pregnancy with ewes offered 100% of predicted metabolisable energy (ME) requirements. Three prolific breed types (Mule (Bluefaced Leicester X Blackface mountain), Belclare X and Lleyn X) were offered one of two silage types (grass (GS) or whole crop wheat (WCW)) resulting in six treatments (n = 15). Where silage intake was insufficient to meet 100% of ME requirements, concentrates were offered to reach 100% of ME allocation per ewe per day. Colostrum yield at one, ten and eighteen hours, combined litter weight (CLW), maternal body weight and body condition score (BCS) change during the final eight weeks of gestation were recorded. The data were analysed using repeated measures and glimmix in SAS (Version 9.4). Ewes offered grass silage produced lambs with a higher CLW (P = 0.03). There was an interaction between breed type and silage type with Mule ewes offered WCW producing a lower CLW than Mule ewes offered GS (P = 0.004), with no difference for Belclare or Lleyn ewes (P > 0.05). Within silage type Mule ewes offered GS had a higher CLW than Belclare ewes (P < 0.05) while within WCW Belclare ewes had a higher CLW than Lleyn ewes (P < 0.05). Other variables did not differ with treatment. In conclusion, a breed specific response was recorded in this study whereby Mule ewes produced a lower CLW when offered WCW compared to GS silage, though no differences were observed in the other breed types studied.