Characterization of the daily rhythm of intake, rumination, and rumen pH in cows fed diets differing in starch and fiber concentration and fatty acid profile
Open Access
- Author:
- Morelli, Michelle Catherine
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Kevin John Harvatine, Thesis Supervisor
Dr. Lester C Griel Jr., Thesis Honors Advisor
Dr. Lester C Griel Jr., Faculty Reader - Keywords:
- dry matter intake
rumination
rumen pH - Abstract:
- The cow has a daily pattern of intake and rumination that causes a daily rhythm in rumen pH. It is expected that the daily pattern of intake and rumination is regulated by the physiology of the cow, the nutrient composition of the diet fed, and the environment and herd management. However, the effect of diet on these rhythms is not well characterized, as intake, rumination, and rumen pH are commonly reported as sums or averages over the day. Rumination, feed intake, and rumen pH data observed every 5 seconds over 4 days in two experiments using Holstein cows were analyzed to determine the effect of diet on the daily rhythms. Two experiments used a duplicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Diets for the first experiment contained either brown midrib (BMR) or its isogenic normal control corn silage at two different concentrations of dietary neutral detergent fiber (NDF; 29% and 38%). The second experiment included diets of ground high-moisture (HM) corn or dry ground (DG) corn at two dietary starch concentrations (32% and 21%). A third experiment used a replicated 4 x4 Latin square design that examined the effect of saturated and unsaturated fatty acid supplements (FS). Treatments included a control diet with no added fat and a 2.5% added fatty acid supplement from a saturated FA, an unsaturated FA, or an intermediate mixture of the saturated and unsaturated FS. For the first two experiments, intake followed a similar daily rhythm regardless of corn type or starch and NDF level. Rumen pH was affected by NDF level for both experiments, with diets with low NDF resulting in lower rumen pH values than high NDF diets, but the daily rhythm was similar between treatments. The DG and HM corn diets did not differ in daily rumination, but BMR decreased rumen pH compared to the normal diets. Type of corn silage also did not significantly affect rumination behavior, but low NDF levels did result in less rumination throughout the day. The third diet showed no significant effect of supplementation of fat or supplement fatty acid profile on intake, rumination, and rumen pH behavior. Overall, intake, rumination, and rumen pH follow a daily pattern that is minimally modified by dietary fiber and starch type and level or fat level and fatty acid profile.