The use of alternative feeding strategies to improve feedlot beef cattle growth performance and nutrient utilization

The use of alternative feeding strategies such as yeast as a feed additive and cotton burrs as a roughage source to improve feedlot beef cattle growth performance and nutrient utilization were evaluated in two experiments. The first experiment evaluated the effects of live yeast fed to natural program beef steers and its effect on growth performance, apparent total tract nutrient digestibility, carcass characteristics, and feeding behavior. In experiment 1, steers (n = 144; 341 ± 52 kg) were assigned to 1 of 3 treatments, Control (CTL), Low Yeast (LY), and High Yeast (HY) in a completely randomized block design (12 pens/treatment). Data were analyzed using the GLIMMIX procedure of SAS, with pen as experimental unit. Gain efficiency tended to be quadratically improved (P = 0.08) between d0 and 183 with LY diet being 4.3% greater than other treatments. The number of premium choice carcasses increased linearly (P < 0.01) with increasing yeast levels at 33.3%, 68.8% and 70%, respectively. There was a tendency (P = 0.09) for choice carcasses to be decreased linearly with increasing yeast level. A quadratic response was observed for nutrient digestibility, in which steers fed LY had improved digestibility (P < 0.01) of dry matter by 5.4%, organic matter by 4.8%, neutral detergent fiber by 15.2%, acid detergent fiber by 20.2%, crude protein by 6.2%, and ether extract by 2.5% compared to HY and CTL treatments. Moderate inclusion of live yeast improved efficiency of nutrient utilization of steers fed steam-flaked corn-based finishing diets, which tended to positively affect growth performance. The second study evaluated the effect of cotton burrs as a roughage source during the transition of beef cattle (hay to finisher diet) on intake, ruminal characteristics, apparent total tract nutrient digestibility, and feeding behavior. Ruminally cannulated steers (n = 6; BW = 235 ± 81 kg) were assigned using a complete randomized design to 1 of 2 adaptation strategies: alfalfa hay or cotton burrs-based. Steers were fed ad libitum once daily, a series of six diets (7-d period each): wheat hay; 4 step-ups; and a finisher. Ruminal fiber degradability, pH, VFA and NH3, and apparent total tract nutrient digestibility were measured. Data were analyzed using GLIMMIX procedure of SAS (wheat hay period used as covariate). Intake was not affected by adaptation strategies (P ≥ 0.16), except for a tendency (P = 0.10) for alfalfa-strategy steers to ruminate more per kg of NDF consumed during finisher diet. Steers fed cotton burrs-strategy had a lower ruminal pH average on step-3 and finisher periods (5.62 and 5.51 vs. 6.04 and 5.83; P < 0.01 and P = 0.05, respectively). A greater area of pH below 5.6 (200 vs. 15 min*pH; P < 0.01); lower ruminal NH3 concentration (5.1 vs. 8.8 mg/L; P < 0.01); and lower digestibility (OM, ADF, and hemicellulose; P = 0.02) during step-3 were also observed for steers fed cotton burrs-strategy versus alfalfa hay strategy, respectively. However, cotton burrs-strategy steers showed greater (P < 0.01) NDF digestibility during step-4; greater (P < 0.01) OM digestibility during finisher diet; and lower acetate/propionate ratio (P = 0.04) with a tendency (P = 0.08) to have greater propionate molar proportion during step-2. Ruminal fiber degradability was not affected by adaptation strategies (P ≥ 0.36). Cotton burrs adaptation strategy induced an improved ruminal fermentation environment during finisher diet, although with riskier ruminal pH and rumination than alfalfa-strategy. Beef cattle diets can include a variety of products to effect growth performance and nutrient utilization, which provides a benefit to beef cattle producers.