This experiment was carried out to study the effect of a directly fed exogenous fibrolytic enzyme on intake and digestion of DM, OM, protein, NDF, ADF, and hemicellulose of alfalfa and ryegrass hay by sheep. Four diets were randomly assigned to four ruminally cannulated lambs using a 4 × 4 Latin square design, repeated in time, with a factorial arrangement (2 × 2) of diets: 1) alfalfa hay; 2) alfalfa hay + exogenous fibrolytic enzymes (enzyme); 3) ryegrass hay; and 4) ryegrass hay + enzyme. Lambs consumed more DM and OM from alfalfa than from ryegrass hay (P < 0.001). The ADF intake was not different between the hays, but NDF intake was lower for alfalfa (P < 0.001). For both hays, the enzyme increased intake of DM (P < 0.01), as well as OM and CP (P < 0.05); however, NDF and ADF intake were not changed. Alfalfa hay had higher apparent digestibility of DM, OM, and CP (P < 0.001), but lower digestibility for NDF, ADF, and hemicellulose. The enzyme increased apparent digestibility of CP, hemicellulose (P < 0.05), and NDF (P < 0.10) for alfalfa. Also, for both hays, the enzyme improved N balance because lambs retained more N (P < 0.05). The enzyme increased (P < 0.05) total VFA concentration (3 and 6 h) for both hays. Results from this trial indicate that directly fed exogenous fibrolytic enzymes may change ruminal fermentation, intake, and digestibility of forages with different nutritive value.

The objective of this study was to evaluate the effects of a slow-release coated urea product (CU, 1% as dry matter of diet) on ruminal disappearance and fermentation, as well as on growth performance of beef steers. Soybean meal in control diet was replaced by CU and steam-rolled corn. For the growth performance trial, 20 beef steers (330±20 kg) were used. For the ruminal trial, four ruminally cannulated steers (230±20 kg) were used.Dry matter intake, daily gain, feed efficiency and carcass dressing were not affected (P>0.05) by CU. Ruminal ammonia N was higher (P<0.05) with CU than control diet. Potential disappearance and total ruminal disappearance of dry matter were increased, while the potential disappearance rate of neutral detergent fibre was reduced with CU. Slow coated urea at 1% of total diet did not affect growth performance and carcass dressing of beef steers.

Effects of zilpaterol hydrochloride (ZH) on growth performance trial (30-day period), and carcass traits of finishing lambs were evaluated. Twenty-eight male Rambouillet lambs (32.7±2.6 kg body weight) were randomly assigned to diets with: 0, 5.3, 10.6, and 15.9 mg ZH/kg dry matter (DM). Average daily weight gain, hot and chilled carcass dressing, muscle conformation, hindquarters width, major and minor torax width, crude protein, and ash of Longissimus dorsi (LD) increased linearly as ZH level increased. Feed conversion was linearly improved, and perirenal fat, leg length, and fat of LD were linearly reduced as ZH level increased. Hot and chilled carcass dressing, dorsal fat, area, and sherar forces values of LD, were cubically affected by ZH level, which at 15.9 mg/kg DM offered the best values. The ZH supplementations at 15.9 mg/kg DM showed positive effects on growth performance and carcass traits.