Effects of feeding CaO treated modified wet distillers grains with solubles or corn stover to cattle on performance, carcass characteristics, and ruminal metabolism

corn stover;distillers grains;calcium oxide;cattle

Duckworth, Matthew ; Felix ; Tara L.

关键词: corn stover;    distillers grains;    calcium oxide;    cattle;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/46690/Matthew_Duckworth.pdf?sequence=1&isAllowed=y

美国|英语

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

【 摘 要 】

Traditionally, feedlot cattle have been fed corn grain; however, recent competition for corn grain for fuel has made it an expensive feed option for cattle producers. Therefore, alternative feeds, like corn co-products, are being considered as energy sources for cattle. Two such co-products are corn stover (CS) and modified wet distillers grains with solubles (MWDGS). These co-products are less expensive and less digestible than corn grain. Chemically treating corn co-products may increase their feeding value for feedlot cattle by increasing fiber digestibility. This may occur through two mechanisms: 1) altering the composition and structure of the cell wall component of forages through delignification, and 2) buffering ruminal acidity. It is currently not known if these mechanisms can be accomplished simultaneously with the use of calcium oxide (CaO) in CS and MWDGS-based diets, nor has the magnitude of the response of CaO in these types of diets been investigated. Therefore, three experiments were conducted. The objective of these experiments was to determine the effects of feeding CaO-treated MWDGS or CS, and corn silage to cattle during the finishing phase on growth, feed efficiency, and carcass characteristics; and on ruminal metabolism and in situ dry matter disappearance using fistulated cattle. Exp. 1: Steers (n = 162) were fed for ad libitum intakes one of three treatments: (1) 20% corn stover, untreated (UCS), (2) 20% corn stover, treated with 5% CaO (TCS), and (3) 40% MWDGS, treated with 2.5% CaO (TDG). Calcium oxide treatment of both MWDGS and CS reduced (P ≤ 0.03) DMI and final BW when compared to feeding UCS. Steers fed TCS had slower (P = 0.03) ADG than steers fed UCS; steers fed TDG were intermediate. Backfat (BF) was decreased (P < 0.01) in steers fed TCS and TDG compared to those fed UCS. Exp. 2: Heifers (n = 138) were fed for ad libitum intakes one of three treatments: (1) UCS, 2) TCS, and (3) 40% corn silage (SIL). Feeding TCS to heifers reduced (P < 0.01) DMI, final BW, yield grade, and BF when compared to feeding UCS and SIL. Heifers fed UCS had the same (P ≤ 0.02) ADG, DMI, marbling score, and BF as heifers fed SIL, although final BW and G:F were decreased. Exp. 3: Fistulated steers (n = 5) were fed for ad libitum intakes in a 5 x 5 Latin square design. Diets were: (1) UCS, (2) TCS, (3) TDG, (4) SIL, and (5) control, 50% cracked corn (CON). Ruminal pH tended to be reduced (P = 0.06) when steers were fed TCS compared to UCS. Steers fed TCS had the greatest (P ≤ 0.05) concentrations of acetate and total VFA. Apparent dry matter digestibility was affected (P = 0.02) by treatment. When steers were fed UCS, dry matter digestibility was reduced, but it did not differ when steers were fed TCS, CON, and SIL diets; those fed TDG were intermediate. Neutral detergent fiber digestibility tended (P = 0.06) to follow apparent digestibility. Feeding TCS increased (P = 0.01) apparent ADF digestibility in steers compared to feeding UCS and TDG, and was similar to feeding SIL and CON. In situ DM and NDF disappearance increased over time with treated corn stover compared to untreated corn stover, and disappearance tended to plateau around 48h. Feeding cattle TCS decreased DMI and reduced ADG although it increased DM and ADF apparent total tract digestibility when compared to feeding UCS. However, cattle fed TDG had decreased DMI and reduced ADG and no improvement in digestibility. Contrary to our hypothesis, feeding cattle CaO-treated corn stover tended to reduce, rather than increase, ruminal pH (P = 0.06). This was most likely caused by increased ruminal fermentation of fiber that increased VFA concentrations (P < 0.01). Cattle fed UCS had better performance than those fed TCS or TDG, and performed similarly to cattle fed SIL, even though the UCS was not as digestible. These data suggest that treating CS and MWDGS with CaO prior to feeding was not effective in enhancing growth performance.