Analysis of the effects of feeding regimens that feed two rations over the day on rumen fermentation products and rumen microbial populations in dairy cattle.
Open Access
- Author:
- Crawford, Christine
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Kevin John Harvatine, Thesis Supervisor
Dr. Lester C Griel Jr., Thesis Honors Advisor - Keywords:
- Rumen fatty acid
Rumen microbial population
Circadian rhythms - Abstract:
- There is a daily pattern of feed intake that results in a change in rumen digesta composition over the day. The object of this study was to investigate the fatty acid composition of rumen digesta and the relative abundance of selected microbial populations in the rumen over the day when cows are fed the same diet for the entire day or diets differing in forage concentration. Samples were analyzed from a previous experiment using nine ruminally cannulated multiparous Holstein cows (158 + 48 DIM, mean + SD) in a 3x3 Latin Square design. Three diets used included a control (CON; 33.3% NDF), a low fiber diet (LF; 29.6% NDF), and a high fiber diet (HF; 34.8% NDF). The control treatment (CON) was fed the control diet at 0900 h, the high/low treatment (H/L) was fed HF at 0900 h and LF at 2200 h, and the low/high (L/H) treatment was fed LF at 0900 h and HF at 1300 h. Rumen samples were collected 8 times during the end of each period to represent every 3 h over the day. Whole rumen digesta was freeze dried and methylated prior to fatty acid analysis by gas chromatography. Additionally, microbial DNA was extracted from 6 of the cows and 10 microbial populations analyzed by Real-Time PCR. Preplanned contrasts compared CON to H/L and H/L to L/H at each time point over the day. There was a time interaction for all fatty acids except cis-10 trans-12 CLA and a treatment by time interaction for C18:0 and cis-9 C18:1. There was an effect of time, but no treatment by time interaction for most microbial populations other than Streptococcus bovis. Megasphaera elsdenii, B. fibrisolvens/Pseudobutyrivibrio, and total anaerobic fungi saw no effect. There is a daily rhythm of ruminal fatty acids that is impacted by diet composition, but the daily rhythm of microbial populations is less impacted.