Effects of pasteurization of potato slurry by-product fed in corn-or barley-based beef finishing diets1

Abstract

Pasteurization of vegetable by-products such as potato slurry (PS) before feeding may be necessary to prevent the spread of pathogens and beef carcass blemishes. We hypothesized that pasteurization would increase ruminal fermentability of PS starch. Four ruminally cannulated crossbred beef steers (initial BW = 432) were used in a 4 x 4 Latin square experiment with a 2 x 2 factorial arrangement of treatments to examine the main effects and interactions of pasteurization (54.4 degrees C for 2 h) of PS and grain type (GT; dry-rolled corn and barley) on ruminal and total tract digestion of beef finishing diets. Diets contained 7% alfalfa hay and 14% PS (DM basis) and were fed ad libitum three times daily. Corn-based diets had 71.7% corn, whereas barley-based diets had 60% barley and 11.7% corn. Pasteurization resulted in greater (P = 0.004) soluble, rapidly degradable starch (34.3 vs. 26.7% for pasteurized and nonpasteurized PS, respectively). Ruminal fluid pH was more acidic (P < 0.07) for corn-based diets than for barley-based diets (P = 0.07) at 0200 and 2100 (sample time x GT; P < 0.05). Ruminal fluid pH was more acidic (P = 0.06) at 1400 for corn-based diets containing pasteurized PS compared with other dietary treatments (sample time x pasteurization x GT; P = 0.04). Minimum and maximum ruminal pH were greater (P < 0.10) for barley-based diets than for corn-based diets. Ruminal fluid pH was < 6.0 for a greater (P = 0.04) proportion of the day for corn-based compared with barley-based diets. In vitro incubation measurements revealed that pasteurization of PS resulted in lower (P = 0.06) ruminal fluid ammonia N concentration. Ruminal fluid ammonia N concentration was lower (P = 0.11) for barley-based diets than for corn-based diets. Steers fed barley-based diets had greater (P = 0.02) DMI and lesser (P < 0.05) total tract digestibility of DM and ADF compared with steers fed corn diets. Pasteurization increased (P = 0.10) total tract starch digestibility. Results indicate pasteurization increased rapidly degradable starch, ruminal starch fermentability, and total tract starch digestibility of PS. Grain type interacted with pasteurization such that feeding corn-based diets containing pasteurized PS resulted in periodic reductions in ruminal pH. Feeding management may be more critical when feeding pasteurized PS in beef finishing diets.

Utilization and application of wet potato processing coproducts for finishing cattle1

“…Monteils et al (2002) reported in sacco potato peel starch disappearance rate was 5%/h compared with 34%/h for wheat starch. In contrast, Szasz et al (2005) reported that ensiled potato slurry starch was 27 to 38% soluble, and the insoluble fraction disappeared in vitro at 14%/h regardless of pasteurization at 54°C. This slurry probably was mostly peels and cooked coproduct based on chemical composition, in which most of the starch would have been gelatinized.…”

Influence of endosperm vitreousness and kernel moisture at harvest on site and extent of digestion of high-moisture corn by feedlot steers

“…Experimental procedures involving animals were approved by the University of Idaho Institutional Animal Care and Use Committee. Six ruminally and duodenally cannulated Angus-Jersey crossbred steers (450 kg of BW), which had been used in a previous study (Szasz et al, 2005), were fed the 6 test grains to examine the effects of kernel vitreousness and moisture at harvest on intake and digestibility of high-moisture corn. Steers were housed in individual pens (approximately 25 m 2 ) and had free choice access to fresh water.…”

“…where a, b, and c = constants from the nonlinear model described previously, whereas k = fractional ruminal outflow rate that was assumed to be 5.0%/h (Orskov and McDonald, 1979). A 5.0%/h outflow rate has been used to estimate effective degradability of feedstuffs in previous trials (Hristov and McAllister, 2002;Szasz et al, 2005). Response variables were analyzed as a 6 × 6 Latin square with a 2 × 3 factorial arrangement using the MIXED procedure.…”

Reducing rumen starch fermentation of wheat with 3% NaOH does not reduce whole tract starch digestibility and increases energy utilization in wethers during heat stress

“…Six zero-hour (T0) flask containing 1 g of grain sample and 100 ml of Kansas State pH 6.8 buffer solution (Marten and Barnes, 1980) followed by 15 min of incubation at 39˚C (Szasz et al, 2005) were included per run. T0 starch and DM disappearance were used to calculate the readily digestible fraction that disappears from the media before microbial fermentation (Ørskov et al, 1980).…”

“…In vitro starch (IVSD) and DM disappearance (IVDMD) for each sample were calculated as the amount of starch and DM that disappeared during the in vitro incubation and were fitted to the non-linear kinetic model (Ørskov and McDonald, 1979;Szasz et al, 2005) [-ct] ) where p is the starch or DM that disappeared at incubation time t (h); a is the soluble and rapidly degradable fraction (%); b is the potentially degradable fraction (%); c is the fractional rate at which b disappeared per hour. The effective DM and starch degradability (ED) were determined as per (Szasz et al, 2005;Anele et al, 2015); ED = a+ bc/(c+k)' where, a, b, and c are the constants obtained from the non-linear model, and k is the fractional outflow rate, assuming a medium passage rate of rumen solids outflow (5.0% h -1 ).…”