Administering the maternal bovine appeasing substance improves fertility in lactating dairy cows.

This experiment evaluated the effects of administering the maternal bovine appeasing substance (mBAS) at the time of artificial insemination (AI) on pregnancy per AI (P/AI) of Holstein cows under commercial dairy conditions. A total of 375 lactating Holstein dairy cows (178 primiparous and 197 multiparous cows) from 2 commercial dairy farms were enrolled. All cows were assigned to an ovulation synchronization + AI protocol when they reached 65 DIM. The protocol included 2 mg of estradiol benzoate + intravaginal progesterone-releasing device (DIB) on d -10, followed by 25 mg of dinoprost tromethamine on d -3, followed by 25 mg of dinoprost tromethamine + 1 mg of estradiol cypionate + 400 IU of equine chorionic gonadotropin + DIB removal and tail paint on d -2. On d 0 (24 h after tail paint application), cows with paint removed were classified as in estrus and inseminated. Cows with intact tail paint were considered not to be in estrus, administered 100 µg of GnRH, and inseminated 8 h later. At the time of AI, cows within farm and parity were randomly assigned to receive mBAS (Ferappease, FERA Diagnostics and Biologicals, College Station, TX; n = 197) or no treatment (CON, n = 178). The mBAS (10 mL) was applied topically to the nuchal skin area (5 mL) and above the muzzle (5 mL). Pregnancy status to AI was verified by detecting a viable embryo with transrectal ultrasonography 32 d after AI. Cows assigned to mBAS or CON had similar DIM at the time of AI, milk yield, and incidence of estrus during the synchronization protocol. Administering mBAS increased P/AI by 12.5 percentage points compared with CON cows (60.2% vs. 47.7%). Based on treatment differences in P/AI and an economic value of $200/pregnancy, mBAS administration yielded a return-on-investment of 833%. This calculation assumed mBAS cost of $3.00/cow, a herd of 1,000 cows in which mBAS yielded 125 more pregnancies, resulting in an economic benefit of $25,000 ($25,000/$3,000 = 8.33). The results of this experiment are novel and provide evidence that mBAS is effective in enhancing the reproductive performance of lactating dairy cows when applied during critical stress-sensitive periods such as AI.