Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2018
Publication Date: 6/25/2018
Citation: Gelsinger, S.L., Coblentz, W.K., Zanton, G.I., Ogden, R.K. 2018. Ruminal and whole-tract diet digestion in calves before, during, and after weaning. Journal of Dairy Science. 101 (suppl. 2):263.
Technical Abstract: An experiment was conducted to determine ruminal and whole-tract digestibility of 2 starter feeds in calves at 5, 7, 9, 11, 13, and 15 wk of age. Ten (n=5/diet) bull calves were cannulated at 3 wk of age. They received milk replacer and one of 2 calf starter diets through wk 7, then starter only (up to 4500 g/hd per d) through wk 15. Diets were a complete pellet (A; 42% starch, 13% NDF) and texturized (B; 31% starch, 22% NDF). Portions of each diet were dried, ground and 1.25g was inserted into concentrate in situ bags (5 cm x 10 cm, 50µm porosity). Each calf received duplicate bags of each diet for a total of 8 bags/calf (2 diets x 2 timpoints). All bags were inserted at the time of starter feeding and removed 9 or 24 h later. This process was repeated over 3d each wk. Daily starter intake and fecal output were recorded during the same 3-d periods. Each diet, refusals, and feces were subsampled, dried, ground, composited by calf by wk and analyzed for NDF and N content. Apparent digestibility coefficients, total intake and output were calculated and submitted to the mixed procedure of SAS with P<0.05 considered significant. In situ ruminal DM disappearance was greatest for diet A at 9 and 24h. Ruminal DM disappearance of both diets increased with age. Disappearance of DM for diet A and B after 24-h incubation increased from 79.4 and 71.7% at 5 wk to 84.3 and 77.1% at 15 wk, respectively. In situ ruminal DM disappearance after 24h tended to be greater for both diets when placed inside the rumens of calves consuming diet B (79.0 vs 77.9%; P=0.10). Total starter intake and fecal output of DM, NDF, and N increased with time and were greater for B calves. While in situ DM disappearance increased, whole-tract starter DM digestibility changed quadratically with time: increasing from 74.7% in wk 5 to 80.7% in wk 7 and then progressively declining to 74.6% in wk 15. Whole-tract digestibility of DM and N was greater (P<0.01) and NDF tended to be greater (P=0.07) for A calves. This is likely due to diet formulation rather than physiological differences between groups as the consumed diet did not significantly effect in situ ruminal DM disappearance.