The daily patterns of feed intake and rumination influence rumen fermentation, rumen pH, and timing of absorbed nutrients in the dairy cow, but the effects of diet composition on these patterns are not well characterized. Data from 3 previously published experiments were examined to determine the influence of dietary starch, fiber, and fatty acids (FA) on daily patterns of intake, rumination, and rumen pH. Dietary neutral detergent fiber (NDF) and starch were investigated in 2 experiments, each with duplicated 4 × 4 Latin square designs with a 2 × 2 factorial arrangement of treatments in cows fed cows 1×/d at 1200 and 1400 h, respectively. To investigate fiber content and digestibility in the first experiment, brown midrib or isogenic conventional corn silage were fed in low- and high-NDF diets (29 and 38%, respectively). To investigate starch source and concentration in the second experiment, ground high-moisture corn or dry ground corn were fed in low- and high-starch diets (21 and 32%, respectively). Effect of fat concentration and saturation was investigated in the third experiment using a replicated 4 × 4 Latin square design that fed cows 1×/d at 0900 h; treatments included a control diet with no added fat and 2.5% added saturated FA, unsaturated FA, or a mixture of the saturated and unsaturated FA. In the first 2 experiments, intake followed a similar daily pattern regardless of starch and NDF concentration or digestibility. Rumination displayed a treatment by time interaction for both NDF and starch concentration, with high-fiber, low-starch diets causing greater rumination overnight but not midday. High-starch diets decreased total daily rumen pH equally across the day, but did not change the daily pattern. Type of corn silage did not affect the daily patterns of rumination or rumen pH, but pH was reduced throughout the day in brown midrib diets. In the third experiment, no interactions between fatty acid supplement and time of day were observed for intake, rumination, or rumen pH. Within all experiments, rumination fit or tended to fit a 24-h rhythm regardless of diet, with the amplitude of the rumination being reduced in low-starch diets and diets containing saturated FA or a mixture of saturated and unsaturated FA. Overall, intake, rumination, and rumen pH follow a daily pattern that was minimally modified by dietary fiber and starch type and level or fat level and fatty acid profile.
Bibliographical noteFunding Information:
The experiments investigating fiber and starch were conducted as part of the MS thesis (EXP 1) and PhD dissertation (EXP 2) of M. Oba (currently of University of Alberta) and we appreciate his contribution to data collection and allowing us to conduct the daily pattern analysis. We recognize the technical assistance of Kan Zhou and Chia Lin (Caroline) Wu of Penn State University. Research was supported in part by USDA Special Grant 2009-34281-20116 (PI: Harvatine), Agriculture and Food Research Initiative Competitive Grant no. 2015-67015-23358 and 2016-68008-25025 from the USDA National Institute of Food and Agriculture (PI: Harvatine), NIH Training Grant no. GM108563 (PI: Salfer), Penn State University including USDA National Institute of Food and Agriculture Federal Appropriations under Project number PEN04539 and accession number 1000803, Cargill Inc. (Wayzata, MN; PI: Allen, EXP 1), Corn Marketing Program of Michigan (Lansing; PI: Allen, EXP 2), Milk Specialties Global (Eden Prairie, MN; PI: Allen, EXP 3), and by the Michigan Agricultural Experiment Station (East Lansing).
© 2018 American Dairy Science Association
- circadian rhythm
- diurnal pattern
- feed intake