Maximising the contribution of fresh and conserved forages in the sheep's diet

A growing global population, the necessity to reduce environmental impact and increasing input costs are placing significant pressures on global sheep production systems to become more resource efficient while returning a viable income to farmers. Potential to deliver solutions to these challenges, through adaption and adoption of alternative forages/forage-based systems is receiving increasing interest in the Irish industry. Alternative home-grown feed sources (forages) on Irish farms can help reduce fertiliser use, concentrate supplementation, and anthelmintic inputs, leading to increased sustainability and profitability at farm level. A key attribute of efficiency and profitability in sheep production systems is ewe performance during late gestation and lactation when ewe energy and protein requirements are highest to support both the neonatal and new-born lamb. The aim of this thesis is to examine if alternative forages can support prolific ewes (Belclare X, Lleyn X, and Mule [Blue-faced Leicester ram and Black-faced Mountain ewe]) during these key production periods with similar or improved ewe and lamb performance. Two experiments were conducted during late gestation, the first compared whole-crop wheat silage (WCWS) with grass silage (GS) where ewe intake and colostrum yield were unaffected but combined litter weight (CLW) was lower for ewes offered WCWS compared to ewes offered GS. In the second experiment Italian ryegrass and red clover silage (IRGRCS) was compared with perennial ryegrass silage (PRGS), ewe metabolisable energy (ME) intake was lower for ewes offered IRGRCS compared to ewes offered PRGS while colostrum yield and CLW were unaffected. Within breed type for both experiments, Mule ewes had lower ME intakes and similar CLW to both other breed types and lower colostrum yield compared to Belclare X ewes. A third experiment examined prolific ewe performance when grazing an alternative forage (AF) system, which consisted of multispecies swards and a perennial ryegrass and red clover sward, compared to a perennial ryegrass (C) system during the lactation period. Ewes grazing the AF system had increased ewe body weight and body condition score at weaning compared to ewes grazing the C system while their lambs had a higher average daily gain (ADG) and weaning weight compared to the lambs of ewes co-grazing the C system. The final experiment compared the performance of Belclare X, Lleyn X, and Mule ewes over a four-year period. Mule ewes had higher fertility rate and scanned litter size compared to the Belclare X and Lleyn X ewes, respectively. Lambs born to Mule ewes had increased ADG, and increased birth and weaning weight per litter reared compared to Belclare X ewes. By developing new feed alternatives capable of supporting prolific breed types, farmers will potentially see increased profits from reduced inputs and will reduce their carbon footprint from current levels per kg of carcass produced helping to meet national and international greenhouse gas emission reduction targets.