Effects of soybean oil or various levels of whole cottonseed on growth performance, carcass traits, and meat quality of finishing bulls

This study evaluated the effects of including various levels of whole cottonseed (WC) or one level of soybean oil (SO) in high concentrate diets fed to finishing beef cattle. Two hundred eighty Nellore bulls were blocked by initial body weight (BW = 349 +/- 33 kg), assigned to 40 feedlot pens and pens within weight block were randomly assigned to treatments: five levels of inclusion of WC (0%, (WC0); 8%, (WC8); 16%, (WC16); 24% (WC24); and 32% (WC32); dry matter (DM) basis] in diets containing 13% (DM basis) of sugarcane bagasse. One additional treatment was formulated to contain similar concentration of lipid as diet WC32 but with no WC, rather using soybean oil (SO). When averaged across the total feeding period, increasing dietary level of WC affected DM intake (DMI), final body weight, average daily gain (ADG), and feed efficiency (G:F; quadratic; P <= 0.01). Compared to WCO, diet SO decreased DMI (P < 0.001), tended to reduce ADG, and final BW (P <= 0.09) but no differences in G:F were observed between this two treatments (P = 0.38). Compared to WC32, bulls fed SO had greater DMI, ADG, final BW, and G:F (P <= 0.02). Increasing dietary level of WC affected hot carcass weight (HCW), dressing percentage, and longissimus muscle area (quadratic; P <= 0.05). Bulls fed SO had greater HCW, dressing percentage, 12th-rib fat (P <= 0.001), and a tendency for greater longissimus muscle area (P = 0.09) compared with WC32. Increasing levels of WC did not affect meat composition (P >= 0.12). No differences in meat composition were observed between bulls fed SO and WCO (P >= 0.24) or bulls fed SO and WC32 (P >= 0.31). Trained panelists detected changes in tenderness (linear; P = 0.05) due the increasing levels of WC in the diets. Compared to WCO (P = 0.06) and to WC32 (P <= 0.05) bulls fed SO have greater tenderness and overall acceptability. Increasing levels of whole cottonseed in high-concentrate diets reduced the DMI of finishing bulls. Levels of WC greater than 15% of diet DM decreased feed efficiency. Including up to 32% of WC in finishing diets had no effects on meat quality or acceptability. No positive effects of increasing dietary fat content from 3.2 to 7.8% with SO were observed on growth performance and overall meat characteristics of finishing bulls.