Analysis of the effects of rumination time on the milk fatty acid profile in Holstein cattle
Open Access
- Author:
- McNew, James Furness
- 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:
- Rumination time
Milk fat
Milk fat depression - Abstract:
- Milk composition is variable among species and influenced by the diet and health status of the animal. The objective of this study to characterize the variation in milk fat concentration and yield between cows and the relationship between these variables prior to determining the relationship with rumination. The biohydrogenation theory is the leading theory for milk fat depression and explains most of the environmental variation in milk fat. Bacteria modify unsaturated fats to saturated fats, and during acidosis the rate of the reaction is decreased in the rumen. The trans intermediates escape the rumen and inhibit milk fat synthesis. Milk samples were collected on two separate days from multiparous Holstein cows. Cows were housed in free stalls with sand bedding and fed ad libitum a TMR once daily. A total of 156 milk samples were collected. 91 were collected on the first sampling and 65 samples were taken on the second. Each sample was composited by milk yield based on the proportion of milk produced at the morning and evening milking. Milk samples were methylated prior to fatty acid analysis by gas chromatography. Mid infrared spectrum was used to analyze milk fat, lactose, and protein and predict categories of milk fatty acids. Linear and quadratic regression were used to correlated specific fatty effects on milk fat percent, along with milk yield. Elevated levels of trans-10 18:1 was indicative of reduced milk fat in the samples, but explained a limited amount of the variation. The rumination data was not available for analysis due to issue with the manufacturer. However, this work demonstrated that there is considerable variation in milk fat and milk fatty acid profile in cows fed the same diet and managed in a similar way that may be explained by rumination time.