Effects of Replacing Barley with Processed Corn on the Growth Performance, Microbial Protein Synthesis and Profitability of Fattening Lambs

Barley as a native cereal is the main source of carbohydrates in fattening sheep. Substituting barley with other sources of carbohydrates, such as corn, could decrease digestive disorders. The objective of this study was to assess profitability, growth performance, and microbial protein production in fattening lambs by replacing barley with different processed corn. To achieve this, a completely randomized design including seven rations with five lambs as replicates were used. The treatments reared in individual cages during an 84-day time frame allowed us to determine body weight, dry matter intake (DMI), feed conversion ratio (FCR), gross profit, and microbial protein production. The results showed that the 40% barley ration had minimum means of final body weight, DMI, daily weight gain (P 0.05), FCR, and gross profit (P 0.10) versus the other rations. Also, the rates of allantoin, uric acid, xanthine, hypoxanthine, and microbial protein in a 100% pelleted corn diet were the highest with a significant difference compared to other treatments. Furthermore, the results of economic models indicated that initial weight and feed cost had negative effects, as opposed to that of daily body weight gain and DMI, which yielded positive effects on the gross profit. In addition, a greater initial weight could decrease partial production elasticity, but utilization of the corn-based rations resulted in more growth rate overall. Of course, the 40% pelleting corn could create a more accelerated growth rate compared to the other processed corn.