Substituição parcial do milho pela massa de fecularia seca sobre o desempenho e características da carcaça de novilhas em confinamento

The objective of this work was to study the effects of partial substitution of corn grain (COR) by dry cassava starch byproduct (CAS) on feed intake, weight gain, feed conversion and carcass physical characteristics in crossbred beef heifers finished in feedlot. Fifty-four heifers, of approximately 15 mo of age and 317 kg mean liveweight, were randomly distributed, in blocks according to breed group, between two treatments, with 27 replicates for performan- ce characteristics and 9 for carcass evaluation. The animals were fed ad libitum twice daily, with corn silage and one of two different concentrates, based on soybean meal and either COR or half COR and half CAS as energy source. No differences (P>0.05) were found between treatments in the variables studied, overall mean values being: daily weight gain (1.1 kg), dry matter (DM) intake (9.1 kg), DM intake/100 kg liveweight (2.6 kg), feed conversion ratio (8.4), warm carcass weight (209.3 kg), carcass weight in arrobas (13.9), carcass yield (51.7%) carcass length (121.1 cm), leg length (71.5 cm), rump roast thickness (25.5 cm), subcutaneous fat thickness (6.6 cm), muscle percentage (30.5), bone percentage (15.5), and muscle plus fat:bone proportions (5.4:1). The dry cassava byproduct can replace 50% of corn in the concentrate without effects on performance and carcass characteristics of crossbred heifers finished in feedlot.