376
Effects of ruminal alkalinizing and/or buffering agents fed to feedlot steers on performance and carcass characteristics
When added directly to the ration, calcium oxide and calcium hydroxide have the ability to increase rumen pH, fiber digestibility, and performance of feedlot cattle fed high concentrate/distillers grains (DG) diets. However, it is unclear which alkali is most effective, if safer, more economical buffers have the potential to improve performance, or if alkali/buffer combinations can significantly improve cattle performance over alkali or buffers fed alone. Thus, this study was performed to determine which alkali, buffer, or alkali/buffer combination is most effective at increasing performance of feedlot cattle fed a corn/DG-based diet. One hundred and twenty Angus x Simmental steers (395.3 ± 12.49) were allotted to 5 treatments based on BW, breed composition, and frame size. Four pens of 6 steers were fed rations supplemented with: no alkali/buffer (control), 1% calcium oxide (CaO), 1% calcium hydroxide (Ca(OH)2), 1% potassium bicarbonate (K2CO3), or 1% CaO + 1% K2CO3. Animals were slaughtered at an average BW of 590 kg. Data were analyzed using the MIXED procedure of SAS. No differences among treatments were found for BW or DMI throughout the study (P ≥ 0.55). Overall ADG was greatest for CaO and least for control (P = 0.09), while overall average daily gain for Ca(OH)2, K2CO3, and Ca(OH)2 + K2CO3 was intermediate and did not differ from CaO or control (P ≥ 0.10). Gain:feed was greatest for CaO for the first half of the study (P = 0.10), while G:F during the first half was intermediate for Ca(OH)2 and did not differ from any of the treatments (P ≥ 0.10) No differences in G:F were noted for the second half of the study or overall (P ≥ 0.16). Days on feed was greatest for control steers intermediate for steers fed Ca(OH)2, K2CO3, and Ca(OH)2 + K2CO3 and lowest for steers fed CaO (P = 0.005). Hot carcass weight, fat thickness, LM area, % KPH, yield grade, and marbling score did not differ among treatments (P ≥ 0.14). Dressing percentage was greatest for steers fed Ca(OH)2, and Ca(OH)2 + K2CO3, intermediate for control steers and lowest for steers fed CaO or K2CO3 (P = 0.05). In conclusion, all alkali and buffer additions decreased the number of days for cattle to reach market weight compared to control; however, CaO appears to be the most effective at improving performance.
Keywords: alkali, buffer, beef cattle