Evaluation of two exotic sheep breeds as meat sires for intensive sheep production systems : A thesis submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science (Honours) at Lincoln College, University of Canterbury

On 15 February 1882, the first frozen meat was exported from New Zealand. A decade later saw the evolution of the lamb export trade. Since this time there has been considerable improvement in the standard of lamb exported from New Zealand. This has been mainly achieved by introducing grade standards and amending them to meet the requirements of New Zealand's trading partners. The development of the export lamb trade has also seen a number of breed changes, reflecting the trends in consumer preferences. Exotic sheep breeds were imported into New Zealand as it was felt that no-one local breed had all the features required for the increasing diversity of New Zealand's export markets (Clarke, 1987). Two of the exotic breeds are the Texel and Oxford Down, whose major role is seen as alternative terminal sires, particularly in the role of producing a heavyweight lean lamb demanded by many markets (Frazer, 1982; Clarke et al., 1984; Marshall, 1985; Clarke, 1987). These exotic breeds were compared under intensive conditions, with the Suffolk, a heavyweight, terminal sire commonly used in New Zealand. The comparison was simulated using a model of an intensive finishing farm in Southland, at a stocking rate of 17.5 stock units per hectare. The model was driven by liveweight gain and incorporated feed supply and demand. Preliminary results were based on slaughtering lambs at 165 days to 257 days old. At all slaughter dates Oxford Down cross lambs were heaviest and had the highest fleece weight. Texel cross lambs were leannest at slaughter, and also the lightest. Using 1988/89 Southland lamb schedule prices, Texel cross lambs gave the highest average return (discounted to March) at $39.58. A further comparison involved slaughtering lambs in early August. Average total prices received (discounted to March) being $54.70 (Texel cross), $49.00 (Oxford Down cross) and $37.15 (Suffolk cross). It is suggested that there may also be a premium paid for Texel cross stock which would further lift returns. It is concluded that the Oxford Down is best suited to early season production with its rapid growth rates. The Texel appears to perform best as a heavyweight (20 kg plus) sire, as there is an insufficient premium paid at present for its medium weight progeny