R. Bras. Zootec.26/Mar/2019;48:e20180004.
Roughage-free finishing diet based on whole corn grain and a mixture of additives for Nellore heifers
This study was carried out to evaluate the effect of a blend of additives (choline, methionine, selenium, and organic zinc) on performance, feed efficiency, rumen parameters, and carcass traits of Nellore heifers finished with roughage-free diet. Nellore heifers (n = 36; average BW = 244±24.1 kg; average 24 months of age) were maintained in a feedlot system for 86 d. Heifers were separated into two groups: control and additive. Heifers in control group were fed a based diet composed of 850 g kg−1 corn grain and 150 g kg−1 of a mineral-vitamin-protein pellet. The additive group was fed a diet supplemented with a blend of choline, methionine, selenium, and organic zinc at 1,667, 4,000, 1, and 24.37 mg kg−1 of the diet dry matter, respectively. The animals were allotted to 18 pens (two heifers/pen), with nine pens per treatment. Heifers were weighed, blood samples were collected, ultrasonography examinations were performed periodically, and hot carcass and papillae samples were taken at slaughter. Data were analyzed as a completely randomized design. The model included the fixed effect of treatments (control and additive). Additive supplementation did not change dry matter intake, performance, or feed efficiency. There was no effect of additives on muscle or fat tissue deposition. Consequently, no changes in hot carcass weight and dressing were found. Overall, additive inclusion did not alter blood parameters, blood electrolyte balance, and rumen traits. Nellore heifers finished with roughage-free diets have no improvement on production traits nor in their rumen health by supplementation with a blend of choline, methionine, selenium, and organic zinc.