Growth and Carcase Characteristics:

Comparative Studies into the performance of South Devon crosses conducted by the United States Department of Agriculture at the Meat Animal Research Centre, Clay Centre, Nebraska.

In the early 1990s, researchers (Williams et al.) at the United States Meat Animal Research Centre developed a computer program which simulated the growth of both fat and fat free tissues in beef steers under a variety of production systems, many of which would be applicable to Australian conditions. Using data previously obtained from cross-breeding studies at Clay Centre, the growth of F1 steers was simulated for the following beef breed sires out of Hereford and Angus dams: Hereford-over-Angus and Angus-over-Hereford, Red Poll, South Devon, Pinzgauer, Tarentaise, Limousin, Brown Swiss, Simmental, Gelbvieh, Maine Anjou, Charolais, Chianina, Sahiwal and Brahman.

Following weaning at seven months, the growth of the steers was simulated to an end-point which met one of the three following targets:
1. Carcase weight of 300Kg.
2. 28% carcase fat.
3. AUSMEAT marbling score of 3.
At slaughter, however, for the results to be considered "feasible", the steers had to be aged 28 months or less, and have a carcase weight of between 300 and 400 Kg.

The following table shows the "feasible" results of the simulated post-weaning performance of the steers grown out on good quality feed, supplemented as necessary to allow them to maintain an average post-weaning growth rate of 1Kg per day. The figures in the columns are the number of post-weaning days which were required to reach the above targets, and the breed groups are ranked in the order in which they achieved all three of these.

From the table, it will be noted that the British cross steers (Hereford, Angus, Red Poll, South Devon) and the Pinzgauer cross steers reached their target fat and marbling contents before they reached the target carcase weight of 300Kg. With the exception of the Charolais cross steers, all the other breeds achieved the required weight and fat content before the target marbling score. In the case of the Chianina and Limousin crosses, however, the required amount of marbling was not achieved by the slaughter age of 28 months. The table clearly shows the South Devon crosses to have reached all three target carcass specifications ahead of all the other beef breed crosses analysed.

The next table simulates the post-weaning performance of the same group of cross-bread steers, but under a different management system. In this system, following weaning at seven months, the steers are backgrounded for approximately ten months on grass where they grow at an average rate of 0.5Kg per day. After 200days they are sent to a feedlot where they are grown out at an average rate of 1.36Kg per day until they reach the above carcase specifications. The figures in the columns are the number of days required in the feedlot to reach the above targets, and the breed groups are ranked in the order in which they achieved all three of these.

In this system, typical of what might be found in Australia, the South Devon cross steers again performed well, requiring only one day more in the feedlot than the top ranking Hereford-Angus crosses. In the case of the Maine Anjou, Brahman, Chianina and Limousin cross steers, it was not possible to achieve the required marbling score with a carcass weight of less than 400Kg.

These two simulations demonstrate the ability of South Devon cross steers to outperform other crosses under two very different management systems.

Reference:

Williams CB, Bennett GL, Keele JW. Simulated influence of postweaning production system on performance of different biological types of cattle. J. Anim. Sci. 1995;73:665-698. Back