Select Mules with improved carcass quality that also last longer The completed Longwool breeding research project has shown that an ‘improved’ Mule/Halfbred ewe, identified through widespread use of a new economic index in crossing sire sheep, can bring huge and sustained benefits to the UK sheep industry during the challenging years ahead. The UK sheep industry has never faced a period of greater challenge than in the last 5-6 years. This began with the devastating impact of Foot and Mouth Disease (FMD) in 2001, followed by the introduction of the Single Payment Scheme and removal of headage payments, and latterly, by declining lamb prices and falling market returns. Of course, the emergence of blue tongue disease in recent months also poses a significant long-term threat to our industry. This means we have to utilise all the technical knowledge and tools at our disposal in order to maximise economic returns and give ourselves the best chance of survival into the future. One of the ways to help ensure a more sustainable future for our sheep enterprises and businesses is to take the guesswork out of breeding and producing sheep. It was with this in mind that the Longwool project was initiated 10 years ago to develop a selection index tailored to the role of crossing sire breeds as the sires of Mule/Halfbred ewes. Mule and Halfbred ewes dominate our lowland flocks, but their carcass quality needs to be improved. This must be achieved without compromising their valued maternal traits, like litter size and mothering ability, while addressing other desirable traits, like improved longevity. It must be remembered that genetic selection results in permanent and cumulative gains, and even though the gain from one year of selection may be modest, over a period of time the benefits become substantial. This Longwool project (funded by Defra, EBLEX, HCC and QMS) involved setting up a large three-site study at Aberystwyth University, at ADAS Rosemaund and Pwllpeiran, and at SAC Edinburgh. A total of 4500 Scottish Blackface and Hardy Speckled Face ewes were mated to 45 performance-recorded Bluefaced Leicester (BFL) ram lambs, selected to represent the full range of carcass and growth traits found within the breed, from within the Penglas Group Breeding Scheme. From these matings, around 2200 Mule wethers were slaughtered to provide detailed growth and carcass data, while 1800 Mule ewes were evaluated over a minimum of five lamb crops for maternal performance and longevity. In summary, the aim of this work from the outset was to address four breeding goals in crossing sires and their progeny: Improve carcass composition, i.e., increase lean content, achieve better conformation and fewer days to finish (in both Mule wethers and terminal sire-cross lambs out of Mule ewes); Achieve good growth rates but limit any increase in ewe mature size (because it is uneconomic to keep bigger Mules!); Maintain Mule ewe maternal attributes, such as their current litter size and good mothering ability that affects lamb survival; Improve ewe longevitysince the profitability of lowland flocks can be markedly improved by reducing flock replacements with older more productive ewes being kept longer. The Longwool selection index that has been developed is an economic index. That means it is based on economic values of individual traits, mainly earnings from lambs marketed, carcass values and cull ewe values, while accounting for the costs associated with providing flock replacements, feed, labour and management time. It is expressed in £ per unit change in the individual breeding goal traits. It takes into account the flow of genes, or qualities, from a crossing sire to its descendants, i.e. to Mule/Halfbred wether lambs and ewes, and to terminal sire-cross lambs out of Mule/Halfbred ewes. The benefits occur immediately in the Mule/Halfbred wether lambs, but take time to accumulate before being seen in terminal sire cross lambs out of Mule/Halfbred ewes, and from the improvements in longevity of Mule/Halfbred ewes themselves. While carcass quality, lambing % and lamb survival were shown to have an important impact on profitability of Mule/Halfbred ewe flocks, the single most important trait was ewe longevity, and this is reflected in the relative weightings given to the various traits within the new index. The robustness and large scale of this study should give crossing sire breeders confidence to adopt the new economic index, which is now ready for use. In order to provide likely economic benefits to the UK sheep industry from its adoption, we have put considerable effort into modelling the genetic gains to provide indications of likely economic benefits that can be expected. For example, if we assume that all BFL breeding flocks engage in genetic selection by using the top 5% of rams from pedigree flocks, then the genetic gains will filter down to all rams bred in those flocks and sold for use in Mule production. In practice, a combination of young rams and stock sires are used within any one BFL flock each year. The calculated maximum benefit to the UK sheep industry from adopting the new index over a 10-year period, including allowing for the cost of performance recording, is £14.5 million. Obviously these benefits are divided between the Mule producer (for better carcass quality Mule wethers) and the commercial lowland producer (from more productive Mule/Halfbred ewes with better longevity, and producing terminal sire-cross lambs with better carcass quality). It is estimated that 13-19% of the total benefit would be obtained by the Mule producer, with the larger remaining 81-87% obtained by the lowland producer. However this does not allow for any increase in sale price of ‘improved’ Mule ewe replacements. Creating a demand and charging a premium for an ‘improved’ Mule ewe would distribute the benefit more evenly over time. So how can the BFL breed achieve this potential? In order to make progress a certain minimum level of recording by BFL breeders is essential. This includes recording of: Pre-mating ewe live weight – at 18 month of age as a minimum; Litter size born – record all lambs born live and dead; lamb survival – record all lambs born dead, dying or fostered; 8-week live weight of all lambs; Live weight and ultrasound muscle and fat depths at 21 weeks (standard Signet scanning service); Ewe longevity – yearly pre-mating inventory of ewes present, sold, culled or died. An enthusiastic and large uptake of this new economic index by crossing sire breeders will ensure a continued widespread influence of these breeds and their progeny on the UK national flock, and a chance to secure the long term market share for Mule/Halfbred ewes. Securing loyalty of customers by providing a better quality product, in terms of carcass, longevity and lamb survival, will help to stave off the many emerging and competing breeds and crosses now seeking to gain advantage in the market place. Improving ewe longevity provides a unique selling point to justify widespread uptake of the new index to provide an ‘improved’ Mule/Halfbred ewe. Mervyn Davies (ADAS), Will Haresign (Aberystwyth University), Rainer Roehe (SAC) and Ron Lewis (Virginia Tech, USA) NOVEMBER 2007