Effect of soybean oil, urea, roughage and a progestigin on the utilization of corn based finishing rations by beef cattle.

Abstract

Three feeding trials, two feeding behavior studies and a digestion trial were conducted to determine the value of soybean oil, urea and roughage in beef cattle finishing rations based on corn. The effect of an injected progestigin was also studied with heifers. The inclusion of the soybean oil decreased average daily gains, feed intake, feed efficiency and ruminal ammonia concentrations but increased ruminal volatile fatty acid concentrations. Carcass characteristics reflected growth performance values. Feeding patterns were unchanged although less total time was spent at the feeder when the oil supplemented rations were fed. The oil did not affect the apparent digestibility of the ration. The deletion of urea from the ration during the terminal phases of the finishing period had no effect on production values. The use of a progestigin resulted in greater gains from heifers fed the all-concentrate rations and less feed required per kg. of gain with heifers fed both the all-concentrate and roughage containing rations. Results from these studies indicate that: (1) the addition of 5% soybean oil to corn based finishing rations depressed animal performance, (2) finishing rations which contain more than 8 to 9% crude protein are probably not necessary from 360 kg. to slaughter weight, and (3) a progestigin improved the performance of heifers in the feedlot.