PSXIV-1 Effects of passage rate on forage intake and digestion in beef cattle

Abstract

Abstract The objective was to evaluate treatments designed to increase passage rate on forage intake and digestion. Eight ruminally-cannulated steers were assigned to a replicated 4 × 4 Latin square design. All steers were fed an ad libitum diet of prairie grass hay (10.4% CP) with the following treatments designed to increase passage rate: no treatment (control; CON), pelleted (PEL), 7% Ca(OH)2 treated (CAOH), and six 2 kg weights inserted into the rumen (WTS). Molasses (3% of diet DM) was added to all treatments. Feed, orts, and total feces was collected on d 12–17 to determine total tract digestibility. On d 17–20, ruminal pH was recorded every 8 hr. Data were analyzed using the MIXED procedure of SAS 9.4 with treatment and period as fixed effects and steer as a random effect. A treatment effect (P < 0.01) was observed for ruminal pH; steers fed CAOH had the highest pH (6.97) with WTS and CON intermediate and PEL being the lowest (6.34). Organic matter intake (OMI) was affected (P < 0.01) by treatment with PEL steers consuming the most (7.86 kg). While steers consuming CON had greater OMI than CAOH (P = 0.04), WTS was not different from CON (P = 0.50). Organic matter digestibility (OMD) was also affected (P < 0.01) by treatment as WTS and CON were the greatest (62.8% and 61.7%, respectively) and CAOH (58.7%) tended (P = 0.08) to be greater than PEL (55.9%). Total digestible organic matter intake (TDOMI) was affected (P < 0.01) by treatment; PEL had the greatest TDOMI with CON being intermediate, and CAOH and WTS being the least. Treatments designed to increase passage rate did affect forage intake and digestion with the greatest effect resulting from pelleting grass hay due to the severe reduction in particle size.