Effects of sorghum particle size on milling characteristics and growth performance in finishing pigs

Abstract

A total of 200 finishing pigs (PIC TR4×1050; initially 46.8±1.24kg) were used in a 69-day growth assay to determine the effects of sorghum particle size on growth performance and carcass characteristics. Pigs were sorted by sex, ancestry, and BW with 5 pigs per pen and 10 pens per treatment. Treatments were a corn–soybean meal-based control with the corn milled to a target particle size of 600μm and sorghum milled to target particle sizes of 800, 600, and 400μm. Actual mean particle sizes were 555μm for corn and 724, 573, and 319μm for sorghum. All diets were pelleted. Pigs were slaughtered (average final BW of 123kg) at a commercial abattoir. Pigs fed the sorghum-based treatments were not different in growth performance, hot carcass weight, backfat thickness, loin depth, or fat free lean index compared to those fed the corn control; however, there was a tendency for pigs fed sorghum-based treatments to have increased (P<0.09) ADG, ADFI, and dressing percentage. As particle size of sorghum was reduced from 724 to 319μm, ADG was not affected but G:F increased (linear, P<0.01). Reducing particle size of sorghum had no effect (P>0.23) on hot carcass weight, backfat thickness, loin depth, or fat free lean index, but dressing percentage tended to improve (P<0.06). In conclusion, linear improvements in G:F were demonstrated with reduction of sorghum particle size from 724 to 319μm. Moreover, our data suggest that the performance of pigs fed corn-based diets were within the range of the responses to those fed sorghum-based diets with varying sorghum particle sizes.