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Graduation date: 1991

Inadequate concentrations of progesterone during gestation can result in impaired embryonic growth and losses. These losses may be attributed to an overactive mechanism of progesterone catabolism or improper luteal function, which results in low concentration of progesterone. Progesterone catabolism occurs to the greatest extent by the liver, which holds a vast supply of cytochrome P450 enzymes and aldo-keto reductases that are involved in steroid inactivation. Insulin is a hormone produced by the pancreas that is involved in glucose uptake and metabolism. Progesterone catabolism is decreased in the presence of elevated insulin levels. Lipoic acid is a naturally occurring antioxidant and multienzyme cofactor which has been shown to increase insulin sensitivity and enhance glucose uptake in a number of species. The objectives of the current experiments were to 1) determine if administering a racemic mixture of lipoic acid by gavage at a dose of 32 mg/kg BW would increase peripheral progesterone concentrations, decrease progesterone clearance rates, or modulate cytochrome P450 2C (CYP2C), cytochrome P450 3A (CYP3A), or aldo-keto reductase 1 C (AKRIC) hepatic enzyme activity, and 2) determine if dosing lipoic acid directly into the rumen at 32 mg/kg BW or 64 mg/kg BW would increase progesterone in the blood, decrease progesterone clearance rates, or modulate insulin. In the first trial, Katahdin cross ovariectomized ewes were randomly assigned to a control or a lipoic acid treatment group. In this experiment, a controlled internal drug release (CIDR) device was inserted in all ewes and serum samples were collected daily for five days to determine progesterone. Liver biopsies were performed on day 10 to measure CYP2C, CYP3A, and AKRI C activity. Following liver biopsies, CIDRs were removed and an intensive blood sampling was performed to measure progesterone decay from peripheral circulation. We found that while lipoic acid does not have an effect on peripheral progesterone concentrations or hepatic enzyme activity, lipoic acid supplemented ewes have decreased progesterone clearance rates compared to control ewes. In the second trial, ovariectomized Katahdin cross ewes were randomly assigned to a control, low lipoic acid (32 mg/kg BW), or a high lipoic acid (64 mg/kg BW) treatment group. A CIDR was inserted in all ewes and blood samples were taken daily for 4 days. Following CIDR removal on day 11, an intensive blood sampling was performed to measure progesterone decay from peripheral circulation. One week following CIDR removal, ewes underwent an intravenous glucose tolerance test. It was found that lipoic acid supplementation did not affect progesterone concentrations, progesterone clearance, or insulin area under the curve. There was a treatment effect such that high lipoic acid dosed ewes had higher area under the curve for glucose when compared to control and low lipoic acid dosed ewes. Although no differences in progesterone concentrations were seen in the second trial, we speculate that the administration method rather than the efficacy of lipoic acid may account for the lack of differences observed. This theory is based on evidence from our first trial that oral lipoic acid supplementation did in fact reduce progesterone catabolism, as well as published data demonstrating that ruminally dosed lipoic acid is less effective than the equivalent oral dose.

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

Graduation date: 1995

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains viii, 46 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 33-38).

The present studies were conducted to check the effects of acute ram introduction into a flock of anestrus ewes in Virginia. Ewes were bled via jugular venipuncture twice weekly and serum samples were radioimmunoassayed for progesterone (P4) content as an indicator of estrous activity. All rams were fitted with crayon equipped marking harnesses for use as an indicator of mating behavior in ewes. The first study tested the effects of introduction of vasectomized rams into a flock: of' 50 Dorset (D) and 50 Hampshire (H) purebred ewes in either May or June. More D ewes ovulated (96% vs 72% for H ewes) and mated (80% vs 20% for H ewes) in May. Of ewes which mated in May 65% D but no H ewes continued to cycle in June after removal of rams. Of ewes exposed to rams in June no difference among breeds was observed in percentage of ewes ovulating but more D ewes (72%) mated than H ewes (44%). Twenty-four percent of D but no H ewes cycled continuously throughout the 68 d or the study. Lambing date significantly affected mating behavior in H but not D ewes. The second study tested the effects of ram breed on incidence of mating and subsequent lambing in Rambouillet x Q Suffolk ewes In June and July of 1984 and 1985. Ewes were Q pre-exposed to either confined Suffolk (S) or Dorset (D) Q yearling rams or no (N) ram for 2 wk prior to breeding by Q either S or D rams. Lambing date was significantly affected by breeding treatment in 1984 and by pre-exposure treatment in 1985. Sixty-three percent of the ewes lambed in 1984 while 65% lambed in 1985. / Master of Science

Thirty-one Dorset (D), 24 Finnish Landrace (F), 35 Barbados Blackbelly x Dorset (BD), 10 Dorset x Finn (F), 24 Finn x Dorset (FD) and 35 grade Rambouillet (R) ewes were exposed to rams in various seasons. Ewes were born in 1979 or 1980; no R ewes were born in 1980. Ewes were bred in April, 1980 (APR80); November, 1980 (NOV80); August, 1981 (AUG81); May, 1982 (MAY82); and April, 1983 (APR83). Ewes born in 1980 entered the study in NOV80. The analytical model used to describe ewe performance included effects of ewe birth year (EBY), breed/EBY, season/EBY, breed x season/EBY and ewe (random). / Master of Science

"March 2003" / Includes bibliographical references (leaves 237-297) / ix, 297 leaves : ill. (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Animal Science, 2005

Bibliography : leaves 120-133. Defines the sources of reproductive wastage in FecB FecÊ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.