Finishing stage of Abeerden Angus steers fattened on winter forage cereals and cereal grain at low rates

Resumen

The finishing stage of fattened steers (> 450 kg animal-1) is usually conducted in feedlots, due to their high energy demands. However, because of the high production costs (PC), middle and small farms are limited in utilization. The adequate energy-protein balance of forage cereals, rich in soluble nonstructural carbohydrates (SNSC), and low in soluble crude protein (SCP) (SNSC SCP-1>1.0), with extra supply of energy from cereal grains, permits obtaining high weight gains (DWG). The object of this trial was to finish rearing animals of British breed with oat (Avena sativa) in a stage of advance emergence and low rates of grains (0.4 % of LW). The study was divided into two stages: 1) 143 steers with 386.06 kg for 70 d, 2) subdivided into two periods: 234 steers, with 383.4 kg for 61 d, and 180 steers, with 416.0 kg animal-1 for 68 d. The nutritional quality (NQ), the DWG, the conversion efficiency (CE), and the PC were measured. The experimental unit was the animal, with 20 repetitions per stage. Linear and non-linear models were tested (variable LW) and the quadratic model was selected (linear). All the parameters were significant (0.95 and 0.97 R2 and 42.42 and 26.78 MSE, respectively). One point eighty-two
kilograms of corn and 1.38 and 1.84 kg animal-1 of sorghum were used, respectively. The ratio SNSC SCP-1 was 1.30 and 1.68. The DWG was of 1.04, 1.223, and 1.103 kg animal-1 d-1, respectively. The CE consisted of 10.78, 8.68, and 9.69 kg DM feed kg meat-1. The PC was 0.90, 0.68, and 0.89 u$s kg produced-1, respectively. The animals reached the finishing stage fattened on pasture, with low grain rate and PC inferior to the feedlot fattening.
Key words: nutritional quality, weight gain, production cost, conversion efficiency.