Case Study: Effects of Supplemental Linoleic and Linolenic Acids on Reproduction in Holstein Cows

A trial was designed to compare reproductive outcomes in a commercial dairy herd fed Megalac (calcium salts of long-chain fatty acids, Ca-LCFA, n = 1,312) or Megalac-R (Ca-LCFA+EFA, n = 708; Church and Dwight Co. Inc., Princeton, NJ). Both products are rumen-inert fat supplements of Ca-LCFA, although Megalac-R contains higher amounts of linoleic and linolenic acids. Beginning at 21 d prepartum, every cow received 0.11 kg/d of Ca-LCFA. All cows were randomly assigned to either product beginning at parturition and continuing until 150 d postpartum (0.16 kg/d). Ultrasonography was utilized to monitor ovarian status on a subset of cows less than 30 DIM. Milk samples were collected for progesterone analysis, and prostaglandins were prescribed by the herd veterinarian as a uterine therapy. Approximately 250 cows were subjected to an Ovsynch regimen to evaluate conception rates. Ultrasound results indicate that by 30 DIM, 49% of cows fed Ca-LCFA+EFA had ovulated compared with 27% of cows fed Ca-LCFA (P < 0.005). Progesterone profiles from milk sample analysis for a subset of multiparous cows showed means of 2.0 and 2.8 estrous cycles per cow by 60 DIM for the Ca-LCFA (n = 18) and Ca-LCFA+EFA (n = 17) treated cows, respectively (P < 0.05). Within the first 60 DIM, 38.9% of cows fed Ca-LCFA and 29.0% of cows fed Ca-LCFA+EFA required prostaglandin treatment (P < 0.005). No difference was detected between treatments in terms of conception rates and services per conception. In summary, the higher concentrations of linoleic and linolenic acids in Ca-LCFA+EFA contributed to improved uterine health and ovulation rates early postpartum compared with Ca-LCFA.