Influence of energy and protein levels on growth rate, feed efficiency, carcase and meat quality of steers

The growth pattern of full fed Friesian steers was one of initial increasing rate of gain followed by a declining rate of gain with increasing bodyweight. Differences in ration energy level which had a significant effect on performance had little influence on efficiency or car-case composition of large breed type steers. In a serial slaughter experiment with Friesian steers, the carcases of animals grown on a grass silage/barley diet had more fat and less meat than those grown on a concentrates/chopped straw diet even though both diets were similar in energy content and supported similar levels of performance. There was an inter-action between the effects of diet and slaughter weight. At low carcase weights there was no effect of diet on composition but with increasing carcase weight, the diet effect emerged. A restriction of 20 per cent in feed intake reduced performance, efficiency and carcase fat content. Résumé Influence du niveau des apports énergétiques et azotés sur la vite.sse de croissance, l’efficacité alimentaire, la qualité des carca.s,ses et des viandes de boeuf