Individual feed intake and performance of finishing steers on ryegrass pasture supplemented with increasing amounts of corn using an automated feeding system

Abstract

Beef production in subtropical areas is mainly based on extensive grazing systems. During the winter, a drop in the forage quantity is common, energy supplementation may help maintain desired production levels. To measure the effect of increasing levels of corn supplementation on the individual forage intake and feed efficiency of finishing steers, we conducted a 99-d experiment during the winter-spring season in Uruguay. Sixty Aberdeen Angus steers (average BW 464.0 ± 29.7 kg) with access to the same sward of ryegrass (Lolium multiflorum Lam.) were managed under a strip-grazing system (sward height post-grazing: 5 cm) and access to an automated supplement feeder until slaughter. Steers were blocked by BW and previous supplement intake and randomly assigned to one of four groups of 15 animals: control (CON, 0.1% BW of corn), low supplementation (LS, 0.4% BW of corn), moderate supplementation (MS, 0.8% BW of corn), and high supplementation (HS, 1.2% BW of corn). Corn was pelleted with TiO2 to estimate fecal production. Diet digestibility was estimated with acid-insoluble ash concentration. The average daily forage allowance was 3.6 kg DM/100 kg BW per day. Supplement intake was 0.5, 1.8, 3.6, and 4.3 kg DM/d for CON, LS, MS, and HS group, respectively. Corn added at 0.4% BW resulted in a greater (P ≤ 0.01) forage intake than other treatments. A quadratic response was observed for forage (P ≤ 0.05) and total diet (P ≤ 0.01) intake to increasing rations of supplements. Total diet digestibility was greater (P ≤ 0.01) for CON and LS steers than for those from MS and HS; and an inverse, linear relationship with supplementation levels was observed (P ≤ 0.01). Steers grew faster with increasing amounts of supplementation (P ≤ 0.01) in comparison to CON cattle, responding quadratically (P ≤ 0.05) to added corn. Cattle from the CON group showed the lowest hot carcass weight (P ≤ 0.01). Finishing cattle on ryegrass pasture (low post-grazing sward height) using 0.6 to 0.8% BW of corn supplementation is the best option to obtain a better intake, performance, and carcass weight, being an alternative to reduce days on fattening and/or the cost of feeding animals.