Superovulation of cattle with equine pituitary extract and porcine ESH

Superovulation has been practiced in cattle for more than 50 years but the results have been highly variable. Scientists at six locations compared a horse pituitary extract (HAP) with a single batch of porcine FSH (pFSH) to determine the efficacy of these hormones to induce superovulation and to test for variability in the superovulatory response. Acetone-dried equine pituitaries were suspended in 40% ethanol containing 6% ammonium acetate, and the supernatant was mixed with 2.5 volumes of cold ethanol. The resulting precipitate was washed with cold ether and dried. Total doses of 18 mg of HAP and 36 mg of pFSH were injected intramuscularly (i.m.) over 4 days, two injections per day, and prostaglandin (PGF(2)alpha; 25 mg, i.m.) was administered on Day 3. Injections were begun on Days 6 to 13 of the estrous cycle. The overall ovulation rates (mean +/- SEM) for HAP and FSH were 8.8 +/- 0.7 and 15.1 +/- 1.0, respectively (n=231; P<0.01). Location interacted (P<0.01) with the type of gonadotropin for the ovulation rate. When expressed as a proportion of the number of corpora lutea, the total number of embryos recovered was greater (P=0.03) for pFSH than for HAP, but there was no difference in the number of Quality 1 and 2 embryos. The results show that HAP can induce a satisfactory superovulatory response, but there was no evidence of reduced variability of response to HAP compared with pFSH.