The University of Arizona

Fatty Acids Improve Reproduction in Dairy Cows Early Postpartum

Bonnie E. Jones1, R. Dean Fish1, Roy L. Ax1, Tony Martin2
1 Dept. of Animal Sciences, University of Arizona, Tucson, AZ
2 Dairy Veterinary Services, Chandler, AZ


A trial was designed to compare reproductive outcomes in a commercial dairy herd (approximately 2000 Holsteins) fed Megalac® (control) or Megalac®-R (Church and Dwight, Princeton, NJ). Both products are rumen-bypass fats supplying essential fatty acids to the small intestine for absorption; however, Megalac®-R contains significantly higher concentrations of linoleic and linolenic acids than Megalac®. All cows were randomly assigned to be fed either product beginning at parturition and continuing until 150d postpartum (0.33 lb/d). Beginning 21d prepartum every cow received 0.25 lb/d of Megalac®.

To monitor ovarian status, real-time ultrasonography was utilized to examine a subset of cows at 2 wk and 4 wk postpartum. All ovarian structures were recorded. Results indicate within cow, numbers of follicles and their distributions in terms of follicular sizes were similar between treatments. However, 49% of cows fed Megalac®-R had ovulated compared to 27% of cows fed Megalac® by 30d postcalving. The difference in ovulation frequency was statistically significant.

Milk samples were collected for progesterone analysis. Progesterone profiles for a subset of cows showed means of 2.0 and 2.76 estrous cycles per cow by 60d postpartum for the control and Megalac®-R treated cows, respectively. This difference was also statistically significant. Prostaglandin (Lutalyse®, Pfizer, New York) was prescribed by the herd veterinarian as a uterine therapy for various uterine problems, such as metritis or uterine tone.

Within the first 60d postpartum, 38.9% of cows fed Megalac® and 29.0% of cows fed Megalac®-R required prostaglandin treatment, with this difference being statistically significant. The incidence of cystic ovaries was less than 3.0% in both treatment groups within the 60d comparison period. Approximately 250 cows were subjected to an Ovsynch regimen to objectively evaluate 21d pregnancy rates. No difference was detected between treatments in terms of first or second service conception rates and services per conception. In summary, Megalac®-R contributed to improved uterine health and ovulation rates early postpartum compared to Megalac®.

to top