Effects of alfalfa on uterine growth of ovariectomized prepubertal ewe lambs

Graduation date: 2003Alfalfa accumulates phytoestrogens and when ingested binds the estrogen\ud receptor and induces morphological changes similar to endogenous estrogens. The\ud objective of this study is to evaluate morphological changes in uteri, vulva, and\ud teats of ovariectomized prepubertal ewe lambs. Eighteen prepubertal ewe lambs\ud were ovariectomized in November 2000 and fed nonestrogenic hay until May 2001.\ud In May, ewes were fed bentgrass straw and cottonseed meal. On day 0 of a 12-day\ud feed trial, ewes were assigned randomly to three treatments (n=6 in each\ud treatment): Estradiol, Control, and Alfalfa. Estradiol treated ewes were fed\ud bentgrass straw and cottonseed meal ad libitum, plus receiving a daily injection of\ud 10 mg estradiol-17β suspended in corn oil. Control ewes were fed bentgrass straw\ud and cottonseed meal ad libitum and received a daily injection of corn oil vehicle.\ud Alfalfa ewes were fed alfalfa ad libitum and received a daily injection of corn oil\ud vehicle. Three blinded observers assigned each ewe a subjective score ranging\ud from 1 (no change) to 4 (significant change) for vulva and teat morphology on\ud Days 0, 1, 3, 5, 7, 9 and 12. Teat length and circumference were measured on Days\ud 1, 7 and 12. Ewes were slaughtered on Day 13, uteri were weighed, and a cross-section\ud was collected from each uterine horn. Cross-sections were fixed in Lillie's\ud Neutral Buffered Formalin and embedded in paraffin wax, sectioned at 4-5 μm, and\ud stained with hematoxylin and eosin. An ocular micrometer was used to measure\ud luminal epithelial cell height. Estradiol treated ewes had heavier (p<0.05) uterine\ud weights and greater (p<0.05) uterine luminal epithelial cell height than that of ewes\ud fed alfalfa or control ewes. Uterine weights and uterine luminal epithelial cell\ud height were greater (p<0.05) in alfalfa fed ewes than control ewes. Vulva scores\ud for estradiol treated ewes were higher than those of control ewes (p<0.05). Alfalfa\ud fed ewes had numerically higher vulva scores than control ewes but the difference\ud was not significant statistically (p>0.05). Teat scores or measurements showed no\ud differences (p>0.05) among treatments. Ewes exhibited slight changes in vulva\ud scores due to treatment, but the most noted effects were observed in uterine growth.\ud This research suggests that uterine weight and uterine luminal epithelial cell height\ud are sensitive to the estrogenic activity of alfalfa and estradiol-17 resulting in\ud morphological changes in estrogen target tissues in the prepubertal ewe lamb