A selection index with the objective of achieving economic improvements in saleable meat yield, calving ease and feed intake has been used in the UK beef industry since the mid 1980`s. In this paper, an improved index, which incorporates estimated breeding values for traits currently recorded in UK pedigree beef cattle, is described. The recorded traits are taken as birth weight, calving ease, gestation length, 400 day weight, ultrasonic fat and muscle depths, and muscling care. The breeding objective is made up of commercial carcass traits, calving ease and gestation length and is directed exclusively towards terminal sire buyers. When all available traits have been recorded in pedigree beef cattle herds, calving traits (birth weight, gestation length and calving ease) explain approximately 30% of the variability in index scores, with the remainder explained by the growth and carcass traits. The expected economic superiority of progeny from the top 40% of bulls ranked on the index, over the average bull, is £2.48 for carcass weight, £.79 for carcass conformation score, £-.05 for carcass fat score, £.37 for gestation length and £.24 for calving case. The overall economic superiority of progeny from the top 40% of bulls (£3.82 is reduced by 17% if both ease and gestation length are not recorded and by 10% if ultrasonic scanning traits are not recorded. Two component indices (for calving and production trait groups respectively) are also proposed to allow commercial bull and semen buyers to adjust emphasis on the two groups of traits depending on their individual production circumstances. In conclusion, the new index incorporates new selection criteria, and a more rigorously defined and transparent breeding objective which should maximise future benefits from performance recording and Best Linear Unbiased Prediction (BLUP) genetic evaluations in UK beef cattle.
Proceedings of the New Zealand Society of Animal Production, Volume 57, , 15-18, 1997
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