Maximising Profitability of Lamb Finishing Systems

Summary

The results showed that to reach 23 kilograms carcase weight was readily achievable and efficient in terms of feed conversion and cost of production, but to achieve 24 kilograms carcase weight was a more costly exercise. In one of the trials lambs grew at 310 grams per day during the first 57 days, but averaged over 82 days, the growth rate was only 220 grams per day (which meant that growth rate was slower in the second period). Lambs that entered the feedlot at lighter weights (37 to 40 kilograms) grew at a faster rate than lambs that entered at heavier weights (45 kilograms and over).

One of the reasons for a slower growth rate of heavier entry weight lambs and of lambs in the final period, was that lambs had already reached their mature weight. Lambs are only able to grow as large as their genetic potential allows, and after this will start to lay down fat. Larger lambs also eat a greater quantity of feed. A small increase in carcase weight can be achieved due to an increase in dressing percentage, however the cost of production to achieve this makes it inefficient. In one trial, growth rates in the final 28 days preslaughter were so low that lambs only put on an extra 2.7 kilograms of live weight (1.2 kilograms carcase weight). It cost an extra $6.66 in feed to gain $3.66 for the extra carcase weight. Increasing growth rates and turning lambs off in six weeks (42 days on feed) also resulted in significantly improved gross margins.