Intake, digestibility, insitu disappearance and ruminal fermentation of bermudagrass hay by lactating beef cows offered corn or hominy feed as supplements.

摘要

Hominy feed, a co-product of dry corn milling, has been evaluated to a limited extent in feedlot and dairy rations, but has not been evaluated as a supplemental energy source for lactating beef cows. The objective of this study was to determine the effect of level of hominy feed supplementation on intake, digestibility, in situ DM disappearance, and ruminal fermentation characteristics of medium quality bermudagrass hay. Five ruminally cannulated lactating beef cows (BW = 596 kg, SE = 13.9) were used in an experiment with a 5 x 5 Latin square design. Treatments were low hominy (LH; 0.25% of BW), medium hominy (MH; 0.50% of BW), low corn ( LC; 0.25% of BW), medium corn (MC; 0.50% of BW) and no supplement (CONT). The cows were housed individually. Supplements were offered at 0800 daily. Hay was offered to maintain 10% refusal and orts were collected daily. Fresh water was offered for ad libitum consumption. A mineral supplement was offered daily. Titanium dioxide was used as an external marker. Fecal samples were collected twice daily to estimate fecal output. Five consecutive 16 d periods were used, with 10 d for adaptation. Forage ruminal DM disappearance was measured using Dacron bags. Ruminal fluid was sampled on d 14 of each period to measure pH and for analysis of concentrations of volatile fatty acids (VFA) and rumen ammonia-N. Hay dry matter intake (DMI) was not affected (P = 0.35) by supplement. Total DMI (kg/d and % of BW) were greater (P < 0.05) for MC and MH compared with the other treatments. Dry matter digestibility did not differ ( P = 0.37) among treatments but MC and MH had greater (P < 0.05) digestible DMI compared with CONT and LC. Hay fraction B (potentially degradable DM) was greater (P < 0.05) for LH and MC compared with MH. Mean ruminal pH tended (P = 0.07) to be greater for LC and CONT compared with LH. Ruminal ammonia-N and total VFA concentrations were not affected (P ≥ 0.77) by supplements. Hominy feed and corn were similar as supplemental feedstuffs for lactating beef cows offered bermudagrass hay.