The Economic Effects of Using Heterozygotes for a Non-functional Myostatin Mutation within a Commercial Beef Production System

The application of molecular genetics to improve meat yield in beef carcases has generated global interest in recent years. Myostatin has been identified as a negative regulator of skeletal muscle mass. Muscular hypertrophy or “double muscling” in cattle has been attributed to naturally occurring mutations in the bovine myostatin gene that result in “inactive” or “non-functional” myostatin. The objective of this study is to take the findings of some recent Beef CRC experimental results relating to selection for the non-functional myostatin mutation, and examine the profitability implications of possible commercial application in the Australian beef industry. A herd-level economic analysis was undertaken using Beef-N-Omics. Inputs included herd costs and returns for a representative selfreplacing beef herd turning off young cattle, as published by the Industry & Investment NSW. Other inputs included pasture growth data for a representative good quality pasture system in the North-west of NSW, and herd production data based on the experimental results. Four scenarios were examined based on different combinations of herd structure and premiums available for muscle score. In a self-replacing system (with a $50 per female cost for the genetic screening test), the increase in gross margin over the base herd was 0.5 per cent ($3 per breeding cow or $2 per ha) when there was a 1 muscle score increase in the average muscle score of the heterozygous progeny. For an increase of 2 muscle scores in the progeny, the improvement in the gross margin was 4.9 per cent ($27 per breeding cow or $13 per ha). In the scenarios where a terminal sire system was applied to utilise the myostatin mutation, the economic benefits are potentially greater. In the case of a 1 unit increase in muscle score over the base herd, a 6.1 per cent increase in the gross margin was achieved ($34 per breeding cow or $17 per ha). If a 2 unit increase in muscle score was obtained a potential 17.7 per cent increase in the gross margin over the based herd was obtained ($96 per breeding cow or $48 per ha).