Effects of dry versus modified wet distillers grains with solubles with or without calcium oxide on economics, growth performance, and ruminal metabolism of beef feedlot steers

beef cattle;distillers grains;calcium oxide

Schroeder, Adam ; Felix ; Tara L.

关键词: beef cattle;    distillers grains;    calcium oxide;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/46608/Adam_Schroeder.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Objectives of this research were to determine the interaction of feeding dry (DDGS) or modified wet (MDGS) distillers grains with solubles (DGS) with or without calcium oxide (CaO) treatment to feedlot steers on: (1) growth performance, economics of gain, and USDA carcass grades; (2) pattern of intake and meal distribution; and (3) diet digestibility and rumen parameters. Exp. 1: Steers (n = 139; average initial BW = 336 ± 75 kg) were used in a randomized complete block design. Treatments were arranged in a 2 × 2 factorial and pens were randomly allotted to 1 of 4 dietary treatments: (1) 50% DDGS with 0% CaO, (2) 48.8% DDGS treated with 1.2% CaO, (3) 50% MDGS with 0% CaO, or (4) 48.8% MDGS treated with 1.2% CaO. The remainder of the diet was husklage, dry rolled corn, and vitamin and mineral supplement.(Exp. 2: Fistulated steers (n = 8; average initial BW = 540 ± 250 kg) were used in a replicated 4 × 4 Latin square design with the same dietary treatments as in Exp. 1). There was no interaction (P ≥ 0.14) of type of DGS and CaO inclusion on DMI, ADG, final BW, or USDA Yield and Quality grades. However, steers fed CaO treated distillers grains (DGS) had reduced (P < 0.01) DMI, regardless of DGS type. Because CaO treatment decreased DMI without affecting (P = 0.66) ADG, steers fed CaO treated DGS had increased (P < 0.01) G:F when compared to steers that were not fed CaO. Variation in DMI found in this experiment could be explained by differences in meal size and distribution. Steers fed CaO treated DGS ate a similar number of meals (P = 0.36), but ate smaller meals (P < 0.01). No effects (P ≥ 0.55) of CaO treatment or its interaction with DGS type were found for total tract DM or NDF digestibility. However, steers fed MDGS had increased (P < 0.01) NDF digestibility when compared to steers fed DDGS. Even though CaO treatment increased the ration cost $3.50 per metric ton of DM, the improved G:F in steers fed CaO treated DGS equated to a $0.098 feed savings (P < 0.01) per kg of BW gain. Even though G:F was similar in steers fed DDGS compared to MDGS, feeding MDGS reduced (P < 0.01) cost of gain and total feed cost over the 95 d experiment (P < 0.01). Exp. 2: There were no interactions (P ≥ 0.12) of DGS type and CaO addition on ruminal pH, VFA, enzymatic activity, methane concentration, or in situ DM and NDF disappearance; therefore, only main effects are discussed. Steers fed DDGS increased (P < 0.01) DMI compared to steers fed MDGS; however, CaO supplementation reduced (P = 0.03) DMI, regardless of DGS type. As expected, addition of CaO increased (P < 0.01) the pH of DGS in the diet by 1.7 pH units. This caused a time by CaO interaction (P = 0.05) for ruminal pH when CaO was added. Steers supplemented with CaO tended (P = 0.09) to have elevated ruminal pH at 1.5 h and had increased (P = 0.03) ruminal pH at 3 h post-feeding; however, ruminal pH did not differ (P ≥ 0.24) the remainder of the day. There was a time by CaO interaction (P < 0.01) for ruminal cellulase activity. Cattle fed 1.2% CaO diets had greater (P = 0.02) ruminal cellulase activity at 0 h post-feeding than cattle fed 0% CaO. Furthermore, feeding supplemental CaO increased (P = 0.04) the ratio of acetate to propionate (A:P) regardless of type of DGS fed. Increased ruminal pH and cellulase activity from supplemental CaO did not increase (P = 0.48) in situ NDF disappearance. No differences (P ≥ 0.48) in ruminal methane concentration were found when comparing DGS type or supplemental CaO. In conclusion, DGS type had little effect on ruminal metabolism. Although CaO increased ruminal pH and cellulase activity at some times post-feeding, it was not enough to affect in situ fiber disappearance or total tract fiber digestibility. However, steers fed CaO treated DGS still had increased feed efficiency and reduced cost of gain when compared to steers that were not fed CaO, regardless of DGS type.