Effects of feeding starch sugar by-products on in situ rumen disappearance rate, growth performance, and carcass characteristics of late finishing Hanwoo steers

Objective: The aim of this study was to determine the effects of feeding starch sugar byproducts (SSBs) on in situ disappearance rate, performance, and carcass characteristics of Hanwoo steers in the late finishing stage. Methods: To determine the in situ disappearance rate, nylon bags filled with 5 g of SSB were inserted into the ventral sac of two cannulated Holsteins cows and incubated for 0, 2, 4, 8, 16, 24, and 48 h. A total of 30 Hanwoo steers were fed the experimental diets, which were basal diet (control) and 7% SSB on an as-fed basis (4.35% dry matter [DM]), formulated according to requirements of the Korean Feeding Standard for Hanwoo. The experiment was conducted over 80 days using a completely randomized block design. Results: Soluble fraction a of DM and organic matter (OM) was 44.20% and 64.60% DM, fraction b was 23.00% and 19.40% DM, and c values (the rate of degradation of fraction b) were 0.04 and 0.04/h, respectively. The effective degradability of DM at rumen solid outflow rates of 0.02, 0.05, and 0.08/h was 59.83, 54.75, and 52.16, respectively, and for OM was 77.78, 73.52, and 71.34, respectively. Initial and final body weight, average daily gain, DM intake, and gain:feed did not differ significantly between control and SSB groups during the entire experimental period. Carcass traits of Hanwoo steers with SSB supplementation were not significantly different between treatments except for dressing percentage, which was greater with SSB treatment. The content of saturated fatty acid (SFA) was greater and that of unsaturated fatty acids (UFA) was lower in the SSB group than in the control group. The ratio of UFA to SFA was significantly lower in the SSB group than in the control group. Conclusion: A total mixed ration containing less than 4.0% DM of SSBs can be used in Hanwoo steers without a decrease in productivity and carcass traits.