The Effect of Stilbestrol upon Lamb Performance in the Feedlot

Abstract

Subcutaneous implantation of a 15 mg. pellet of stilbestrol at the beginning of the feeding period increased significantly the rate of gain in lambs being fattened on various Kansas rations. Lambs given a second implant after 70 days of feeding did not gain any faster than those given only one implant. Carcass grades and dressing percentages were slightly lower in the treated lambs than in the untreated ones. Twelve lambs were lost (of 517 in the experimental tests at Garden City) from prolapse of the rectum and from excessive swelling and inflammation in the rectal or perineal region, or showing symptoms similar to those produced by urinary calculi. All 12 lambs dying from these causes had each received two implants of 15 mg. of stilbestrol. Virtually all the treated lambs, both those receiving one pellet and those receiving two, had preputial swelling and indicated distress during urination. Many of the treated lambs showed visible swelling in the perineal region. Measurements taken of the uro-genital systems of treated and untreated lambs revealed enlarged seminal vesicles, bladder, ampullae, urethra, prostate gland, and bulbo-urethral glands in the treated lambs. The most noticeable changes were seen in the Cowper's glands where in severe cases, a cul-de-sac filled with urine was developed. A possible explanation of the symptoms of urinary calculi and rectal prolapse in the treated lamb is offered.