A feedlot experiment with steers showed that feeding 20% rice straw did not improve concentrate intake, daily gain or carcass weight when whole shelled corn was fed but was beneficial when the corn was ground. This experiment further showed that feedlot performance was improved when steers were fed whole rather than ground corn as the entire diet. Urea supplementation improved the performance of cattle fed either corn ration. Three metabolism experiments were conducted with steers fed whole or ground shelled corn fed with or without rice straw. The addition of 20% rice straw decreased nutrient digestibility as well as the digestible energy content of the concentrate. This depression was more pronounced in nutritionally unbalanced rations. A comparison between whole and ground shelled corn fed with 20 or 60% rice straw showed that whole corn was more digestible than ground corn in the 20% and similarly digestible in the 60% rice straw rations.

Three feedlot experiments were conducted to study the influence of feeding various protein supplements with whole and ground shelled corn. There was no significant difference in the total dry matter intake due to the physical form of the corn. Average daily gain and carcass weight were generally higher with whole than ground corn. Feeding a 6% urea-94% molasses mixture free-choice resulted in greater intake, daily gain and carcass weight than feeding 6% urea in a dry supplement as 25% of the total ration. There were no significant differences in the average daily gain and carcass weight of cattle fed soybean meal or urea-molasses supplements. A complex supplement, composed of urea and plant protein, fed at the rate of .5 lb (227 g) per day gave a variable response which was attributed to a reduced intake as a result of an ammonia odor from the supplement.

Two metabolism trials were conducted with steers to determine the influence of grinding and nitrogen source on the digestibility of shelled corn, the effect of roughage on digestible energy content and to compare corn and sorghum grain. Grinding the corn or replacing the soybean protein with urea did not influence energy, dry matter, nitrogen-free extract, or crude protein digestibility or digestible energy content. The addition of 20% rice straw decreased the digestibility of all nutrients as well as the digestible energy content of the concentrate. There was a consistent trend for the pH and the proportions of acetate and butyrate to be higher and propionate and total VFA to be lower on the whole than on the ground corn rations, which suggests that the whole corn has some roughage characteristics. There was very little difference in the digestibility or ruminal fluid when sorghum grain or corn rations were fed.

Two feedlot trials were conducted to study the performance of steers fed rations containing 5 or 20% rice straw, alfalfa hay, rice hulls, 5% oyster shells and all-concentrate. Total consumption of the 20% rice straw ration was greater than for other rations. However, concentrate intake was similar for the two levels of rice straw. The difference in carcass weights can be largely explained by concentrate intake. The similar concentrate intake, gain and carcass weight of rice straw fed steers suggest that 5% rice straw is adequate under conditions of this experiment while a comparison with the all-concentrate ration suggests that some roughage is needed. Alfalfa hay, possibly because of the fineness of grind did not satisfy this need. Gains, carcass weights and grades of steers fed 20% rice hulls, or 5% oyster shells were lower than when other rations were fed, indicating that these are not satisfactory roughage replacers at these levels. These data suggest that the response of fattening steers to roughage level depends on roughage source. Rumen fluid from steers fed 20% rice straw had the highest pH followed by rumen fluid from steers fed 20% rice hulls which was higher than from steers fed all-concentrate, 5% alfalfa hay, rice hulls or oyster shells Total volatile fatty acid concentration followed an inverse pattern in that rumen fluid from steers receiving 20% rice straw had a lower concentration than from steers fed other rations. Rumen fluid from steers fed 20% rice straw had more acetate and less propionate than from steers fed 20% rice hulls and the fluid from both had more acetate and less propionate than from steers fed other rations.