Brief Summary of Minutes of Annual Meeting

The meeting was called to order at 8 am on Thursday, May 30, 2002 by Chair Tim Rozell (KS). Meeting participants introduced themselves and 2 new members, Andrea Cupp (NE) and Derek McLean (WA), were welcomed. Colin Kaltenbach (AZ), administrative advisor, explained the new electronic format for the annual report which is due within 60 days of the meeting. Due to the limited character field available for the minutes, the group decided that the annual report should include a brief summary of the minutes excluding details regarding collaborations for the upcoming year.

Deb Hamernik (USDA-CSREES) provided news and updates regarding personnel, budgets and funding opportunities at USDA. She also explained her role as National Program Leader for Animal Physiology. Earlier receipt deadlines for FY 2003 NRI applications were noted, including December 1 for Animal Reproduction.

The business meeting began at 8:50 am with the election of Gary Moss (WY) as Member-at-Large for 2003. On behalf of the group, Chair Rozell (KS) expressed appreciation to Dale Holcombe (NV) for making local arrangements for the meeting in Reno. Dennis Hallford (NM) moved that the 2003 annual meeting be held in Reno, NV. The motion was seconded by Jerry Reeves (WA), and passed. The meeting will be held May 29-30, 2003. Dale Holcombe (NV) volunteered to gather information about possible meeting locations in the Reno area. This information will be disseminated to the group later in the year.

The group was reminded to send assay methods and procedures that may be of interest to the group to Jim Berardinelli (MT) so they can be compiled on the W112 web site (www.repro.montana.edu/W112). The purpose of this list is to provide an accessible archive of assay procedures that will not be lost as people retire.

The manuscript on estrous synchronization authored by Mike Day (OH) and Tom Geary (MT) was discussed briefly. Tom offered to contact Mike to check on the status of the paper. Troy Ott (ID) suggested Professional Animal Scientist as an appropriate journal for publication of this manuscript.

Members discussed news at each of their respective stations. Several position openings were noted, including department chairs at Colorado State, Michigan State, and Texas A&M. Jerry Reeves (WA) pointed out that Derek McLean had recently been hired at Washington State and plans to become a member of W112.

The remainder of the meeting was devoted to presentations and discussions of individual station reports and discussions of and arrangements for collaborations for 2002-2003. Plans for collaborations were recorded in writing and submitted to Secretary Adele Turzillo (AZ) who will compile them and make them available to the group.

OVARIAN BIOLOGY

1. Follicular Development

Better methods to synchronize estrus and ovulation will require the ability to control ovarian follicular development and atresia. Results in heifers indicated that atresia of dominant bovine follicles is not caused by altered expression of oxidative stress response proteins. Oxidative stress does not appear to mediate follicular atresia in cattle.

Growth/differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are ovarian growth factors. Immunization of ewes against GDF9 and BMP15 enhanced ovulation rate and may provide an alternative to current superovulation procedures.

Binding of follicle-stimulating hormone (FSH) to its receptor on granulosa cells initiates follicular development and differentiation. Two functional variants of the FSH receptor that appear to have unique structural characteristics and biological activities were found in bovine and porcine granulosa cells. Determining the functionality of these variants may increase our understanding of ovarian follicular development.

Cystic ovaries have a negative impact on reproductive efficiency. In lactating dairy cows, high peripheral concentrations of LH did not cause development of cysts. Pulsatile infusion of LH decreased the interval to first ovulation in postpartum cows.

2. Sexual Behavior

Sexual behavior and improvement of breeding capacity was studied in rams. Selecting ewes is unlikely to effect sexual behavior or orientation of their male offspring. Conditions for monitoring sexual behavior need to be considered carefully to make sound decisions on sexual performance. The naloxone challenge test cannot discriminate between asexual and sexually active rams. Sexual performance in Polypay rams did not alter reproductive performance of Polypay ewes. Serving capacity tests should be used without emphasis on level of sexual performance to obtain 60% lambing rate. The moderate heritability and high repeatability for ram sexual performance imply that 1 screening for this trait is adequate and favorable response to selection for serving capacity can be expected. Selection for ram libido score may enhance fertility despite small genetic correlations of libido score with number of lambs born.

Inhibin is a gonadal protein that exerts negative feedback on FSH secretion. A sensitive, specific 2-site immunoassay for ovine and bovine inhibin B was developed. In rams with detectable inhibin B concentrations, secretion was pulsatile. This assay may facilitate a better understanding of male reproductive physiology and development of strategies to assess testicular function in rams and bulls.

3. Ovulation

Follicular rupture and subsequent oocyte release are prerequisites for pregnancy. The preovulatory LH surge initiates proteolytic degradation of the follicle wall preceding ovulation. Matrix metalloproteinases (MMP) degrade extracellular matrix components. The LH surge increases MMP-1 and MMP-13 in bovine preovulatory follicles. MMP-1 and MMP-13 may mediate degradation of the follicle wall prior to ovulation. LH surge-induced elevations in intrafollicular prostanoid synthesis are required for follicle rupture in dairy cattle.

4. Luteal Function

The endogenous diazepam endozepine was detected in ovine luteal tissue and was 6 times higher in large luteal cells compared to small luteal cells. Since endozapine stimulates steroidogenesis, endozapine may mediate high constitutive production of progesterone by large luteal cells. These results suggest potential development of pharmaceutical products that would reduce embryonic wastage caused by luteal insufficiency.

5. Environmental Control

The role of thyroid hormones in seasonal anestrus was investigated in ewes. Thyroid inhibition with large dosages of propylthiouracil (PTU) decreased serum T4, inhibited onset of anestrus and extended the breeding season. PTU induced hypothyroidism in pregnant ewes. Decreasing sunlight and solar radiation appear to play little role in onset of cyclicity once puberty is attained in Rambouillet ewes in southern New Mexico.

Season and steroid hormones have important effects on GnRH and LH secretion. Anti-gonadotropic decapeptide (AGD) is a potent inhibitor of GnRH secretion. Experiments in ewes suggest that AGDs inhibition of GnRH secretion is predominant during anestrus. In another study, non-genomic effects of estradiol (E) were demonstrated in ovine pituitary cells. Rapid inhibitory actions of E on luteinizing hormone (LH) secretion were mimicked by membrane impermeable forms of E, suggesting that the inhibition occurred at the level of the plasma membrane. These results could lead to development of novel methods to regulate LH secretion.

Systemic inflammatory stress activates gene expression pathways in the hypothalamus that may play a role in neurobiological regulation of the stress response and mediate negative effects of stress on reproduction. Results indicate that stress, or stress-like levels of cortisol, interrupted follicular development and ovulation in ewes. The anti-gonadal effect of cortisol is due in part to reduction in pituitary GnRH receptor expression.

Several studies focused on relationships between nutrition and reproduction. Prepartum diets high in linoleic acid had no effect on subsequent reproductive performance in beef heifers. However, postpartum supplementation with dietary oils high in linoleate may influence reproduction in heifers by altering the synthesis and/or secretion of PGF. Feeding an ionophore antibiotic (Lasalocid) prior to calving and during the postpartum period increased calving rate. Because whole cottonseed reduced body weight gain, body condition score, antler growth, and testis growth in Red Deer stags and Fallow bucks, supplemental feeding of whole cottonseed to deer should be avoided. Elevated concentrations of progesterone in ewes fasted during the luteal phase may result from decreased metabolism reflected by changes in thyroxine and insulin.

Adipose-derived leptin has been implicated in the regulation of energy metabolism, feeding behavior, and reproductive hormone secretion. Peripheral concentrations of leptin were positively correlated with scrotal circumference and serum testosterone in growing bulls and with back fat and body condition scores in heifers. Brahman cows tended to have greater concentrations of metabolic hormones than Angus cows and this difference may be sensitive to forage quality. High levels of leptin in milk early in lactation may provide a mechanism for thermoregulation, satiation, and homeostatic endocrine control in the neonate. Cows with higher concentrations of leptin had shorter postpartum interval. Leptin concentrations were positively correlated with IGF-1, body weight and body condition score, and negatively correlated with postpartum interval.


UTERINE BIOLOGY

1. Maternal Recognition of Pregnancy

The bovine uterus is exposed to conceptus-derived interferon-tau (IFNt) during early pregnancy. IFNt is anti-luteolytic and stimulates several genes including the ubiquitin paralog ISG17. Induction of ISG17 is a pregnancy-specific response not observed with components of the ubiquitin/proteasome-dependent degradation pathway. PI3K appears to have a role in IFNt signaling in bovine endometrial (BEND) cells to reduce PGF secretion.

Mx is another IFNt stimulated gene expressed during diestrus and early pregnancy in ovine endometrium. Mx may be involved in pregnancy establishment and maintenance and co-regulated by steroids. Uterine Mx expression may be a general phenomenon during early pregnancy in domestic ungulates and is found at the fetal/maternal interface throughout gestation. Manipulation of Mx expression may reduce early embryonic wastage. Assaying for Mx or other interferon induced proteins in blood may provide a method for early detection of bred, non-pregnant, ruminants allowing for faster re-breeding and fewer days open.

2. Placental Development

Regulation of endometrial and placental progesterone secretion was investigated. LH appears to stimulate endometrial PGF secretion in nonbred ewes and prevent luteolysis 15-50 d post breeding. Uterine/placental PGF secretion is not reduced until the end of the first trimester, and thus may play a role in the 30-40 percent of pregnancies lost during this time. Caruncular/placental secretion of PGE2 appears to be regulated by PSPB after d 50 post breeding.

Exposure of pregnant ewes to hyperthermia (HT) during maximal placental development causes placental insufficiency and intrauterine growth restriction (IUGR). Ultrasonography was used to monitor placentome development in IUGR pregnancies, and Doppler velocimetry provided a good index of umbilical and fetal hypertension. These methods could be used to study maternal nutritional influences on fetal and placental development. HT alters fetal placental angiogenesis, similar to the response to hypoxia. Further study of these 2 environmental insults on placental and fetal development will help differentiate mechanisms of placental insufficiency and IUGR.

3. Fetal maturation

A study was designed to characterize conceptus development in in vivo- and in vitro-derived bovine pregnancies. Results suggest the importance of placental development in the birth of large calves derived from in vitro-produced embryos. High birth weights may be a consequence of aberrant placental development due to disruption of placental restraint on fetal growth toward the end of pregnancy.

ANIMAL DISEASE

1. Mastitis control

The effect of post-weaning fast and intramammary antibiotic infusion on hormone profiles during the drying off period in ewes was investigated. Fasting animals for 2 d at weaning influenced concentrations of IGF-I, GH, insulin, T3 and T4. Intramammary antibiotic infusion affected serum insulin, GH, T3 and T4 concentrations during the drying off period. These data suggest that hormones associated with lactation are influenced by both fasting and intramammary antibiotic infusion following weaning.

REPRODUCTIVE TECHNOLOGY

1. Immunocastration

Aggressive behavior was evaluated in bulls, steers and bulls actively immunized against GnRH. Data indicate active immunization against GnRH is an effective alternative to physical castration. Immunocastration consistently lowers aggressive behavior and is likely to facilitate handling and management of male cattle on the ranch and feedlot.

A sterilization vaccine against GnRH is being developed as an alternative to surgical spaying of feedlot heifers. Ovalbumin-GnRH fusion protein was the best antigen for immunization. Results indicate that GnRH immunocastration in bulls decreased testosterone (as indicated by body weight gains compared with surgically castrated steers) and scrotal size compared to intact bulls. A double hormone target sterilization vaccine (LH beta subunit and GnRH) is being developed to overcome the problem of non-responding animals.

2. Assisted reproductive technologies

Widespread use of artificial insemination (AI) in beef cattle on the Western range will require simple and efficient methods to synchronize estrus. Select Synch and CO-Synch are current protocols that use exogenous hormones to synchronize estrus. Results in beef heifers indicated that injection of GnRH 1 wk prior to CO-Synch did not increase pregnancy rate. Since ovulation of smaller follicles may result in higher embryonic mortality, protocols may be improved by assuring adequate follicular growth before ovulation. Addition of MGA at the time of PGF during Select Synch delayed estrus and ovulation and resulted in ovulation of larger follicles. However, pregnancy rates of cows receiving a bolus of MGA at the time of PGF with CO-Synch and timed AI were similar to control cows. The MGA/PGF protocol increased estrus synchrony and pregnancy rates in beef heifers compared to Select Synch and MGA/Select Synch. In postpartum anestrous cows, a progesterone-releasing CIDR induced and synchronized estrous cycles but MGA for 7 d had no effect. Fertility was improved following termination of pregnancy at 35 d of gestation compared to d 25 or during the luteal phase in non-pregnant cows.

Success of farming muskoxen for qiviut (underwool) in Alaska requires husbandry tools specific for this species. Importance of the bull in seasonal ovarian activity and his effect on estrous synchrony were tested. Introducing bulls in August truncated the breeding period to 2 wk (4-6 wk shorter than normal). A radiotelemetric system was found to be an excellent tool for estrus detection. This information will support development of management strategies to increase reproductive efficiency in reindeer and muskoxen.

Importance of the bull in the onset of ovarian activity was also investigated in beef cows. The effect of bulls on resumption of estrous cyclicity in first-calf beef cows was independent of type of suckling. Cows exposed to bulls later (d 55) during postpartum anestrus responded faster to the biostimulatory effect of bulls. Exposing cows to bulls or their excretory products did not alter breeding performance in first-calf restricted suckled beef cows using a modified CO-Synch protocol, but presence of a bull may enhance breeding performance of cows bred at timed AI using CO-Synch.

In red deer hinds, electronic estrus detection using the Heat Watch System was not as reliable for estrus detection as marking by stags.

Bovine spermatogonial stem cells were transferred to nude mouse testis and colonized as round cells that appear to be spermatogonial in nature.

PLANS FOR THE COMING YEAR

Many new and on-going collaborations among participating research stations are planned for 2002-2003. Space limitations prohibit detailed description of these collaborations in this report. A complete list may be obtained from the Secretary (Turzillo) or Administrative Advisor (Kaltenbach).

Alexander B, Rose J, Stellflug J, et al. Fos-like immunoreactivity in brain regions of domestic rams following exposure to rams or ewes. Phys Behav 2001;73:75-80.

Alexander B, Rose J, Stellflug J, et al. Low-sexually performing rams but not male-oriented rams can be discriminated by cell size in the amygdala and pre-optic area: A morphometric study. Behav Brain Res 2001;119:15-21.

Alexander B, Rose J, Stellflug J, et al. Low-sexually performing rams but not male-oriented rams can be discriminated by cell size in the amygdala and preoptic area: A morphometric study. Behav Brain Res 2001;119:15-21.

Alexander B, Rose J, Stellflug J, et al. Fos-like immunoreactivity in brain regions of domestic rams following exposure to rams and ewes. Phys & Behavior. 2001;73:75-80.

Ashley M, Holcombe D. Effect of stress induced by gathers and removal on reproductive success of feral horses. Wildlife Soc Bul 2001;29(1):248-254.

Bakke L, Dow M, Cassar C, et al. Effect of the preovulatory gonadotropin surge on matrix metalloproteinase-14, matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-2 expression within bovine periovulatory follicular and luteal tissue. Biol Reprod 2002;66: 1627-1634.

Banta M, Holcombe D. The effects of thyroxine on metabolism and water balance in a desert-dwelling rodent, Merriams kangaroo rat (Dipodomys merriami). J Comp Phys 2002; B 172:17-25.

Baratta M, West L, Turzillo A, et al. Activin modulates differential effects of E2 on synthesis and secretion of FSH in ovine pituitary cells. Biol Reprod 2001; 64:714-719.

Bazer F, Spencer T, Ott T, et al. Mediators of maternal recognition of pregnancy. In The Endometrium. S.E. Glasser, Ed., Harwood Academic Publishers, UK 2002; pp169-193.

Bellows R, Grings E, Simms D, et al. Effects of feeding supplemental fat during gestation to first-calf beef heifers. Prof Anim Sci 2001;17:81-89.

Berardinelli J, Weng J, Burfening P, et al. Effect of excess degradable intake protein on early embryonic development, ovarian steroids, and blood urea nitrogen on Days 2, 3, 4, and 5 of the estrous cycle in mature ewes. J Anim Sci 2001;79:193-199

Binelli M, Subramaniam P, Diaz T, et al. Bovine interferon-t stimulates the Jak-STAT pathway in bovine endometrial epithelial cells. Biol Reprod 2001;64:654-665.

Bolte M, Hess B, Means W, et al. Feeding lambs high-oleate or high-linoleate seeds differentially influences carcass fatty acid composition. J Anim Sci 2002;80:609-616.

Browkaw L, Hess B, Bartle S, et al. Effect of hand-fed versus self-fed supplementation on growth and reproductive performance of developing heifers. Prof Anim Sci 2002;18:38-43.

Carr A, Russell W, Stobart R, et al. Research Note: Is there an influence of individual rams on ewe prolificacy? Sheep & Goat Res J 2001;17 (1):27-28.

Cassar C, Dow M, Pursley J, et al. Effect of the preovulatory LH surge on bovine follicular progesterone receptor mRNA expression. Dom Anim Endo 2002;22:179-187.

Daniel J, Sterle S, McFadin-Buff E, et al. Breeding ewes out-of-season using melengestrol acetate, one injection of progesterone, or a controlled internal drug releasing device. Theriogenology 2001;56:105-110.

Devaskar S, Anthony R, Hay W. Ontogeny and insulin regulation of fetal ovine white adipose tissue leptin expression. Am J Physiol 2002;282:R431-438.

Dow M, Bakke L, Cassar C, et al. Gonadotropin surge-induced upregulation of the plasminogen activators (tissue plasminogen activator and urokinase plasminogen activator) and the urokinase plasminogen activator receptor within bovine periovulatory follicular and luteal tissue. Biol Reprod 2002;66:1413-1421.

Dow M, Bakke L, Cassar C, et al. Gonadotropin surge-induced upregulation of messenger RNA for plasminogen activator inhibitors 1 and 2 within bovine periovulatory follicular and luteal tissue. Reprod 2002;123: 711-719.

Fortune J, Rivera G, Evans A, et al. Differentiation of dominant vs subordinate follicles in cattle. Biol Reprod 2001;65:648-654.

Funston R, Ansotegui R, Lipsey R, et al. Synchronization of estrus in beef heifers using either melengesterol acetate (MGA)/prostaglandin or MGA/Select Synch. Theriogenology 2002;57:1485-1491.

Geary T, Salverson R, Whittier J. Synchronization of ovulation using GnRH or hCG with the CO-Synch protocol in suckled beef cows. J Anim Sci 2001;79:2536-2541.

Geary T, Whitter J, Hallford D, et al. Calf removal improves conception rates to the Ovsynch and CO-Synch protocols. J Anim Sci 2001;79:1-4.

Holmberg B, Morrison C, Keisler D. Endocrine responses of ovariectomized ewes to i.c.v. infusion of urocortin. J Endo 2001;171:517-524.

Holloway J, Warrington B, Forrest D, et al. Preweaning growth of F1 tropically adapted beef cattle breeds x Angus and reproductive performance of their Angus dams in arid rangeland. J Anim Sci 2002;80:911-918.

Kim L, Weems Y, Bridges P, et al. Effect of indomethacin, luteinizing hormone, trilostene, mifepristone, ethamoxytriphetol(MER-25), or pregnancy on secretion of PGE, PGF2 alpha, and P4 by ovine corpora lutea of pregnancy or the estrous cycle. PGs & Other Lipid Med 2001;63:189-203.

Lewis A, Berardinelli J. Gross anatomical and histomorphometric characteristics of the oviduct and uterus during the pubertal transition in the sheep. J Anim Sci 2001;79:167-175.

Manikkam M, Bao B, Rosenfeld C, et al. Expression of the bovine oestrogen receptor-beta (bERbeta) messenger ribonucleic acid (mRNA) during the first ovarian follicular wave and lack of change in the expression of ERbeta mRNA of second wave follicles after LH infusion into cows. Anim Repro Sci 2001;67:159-69.

Manikkam M, Calder M, Salfen B, et al. Concentrations of steroids and expression of mRNA for steroidogenic enzymes and gonadotropin receptors in bovine ovarian follicles of first and second waves and changes in second wave follicles after pulsatile LH infusion. Anim Repro Sci 2001;67:189-203

Mansur R, Holcombe D, Bruce L, et al. Effect of colostrum intake on serum hormone concentrations and immunoglobulin G (IgG) absorption in neonatal lambs. Sheep & Goat Res J 2002;17:33-38.

Martin P, Davis D, Weiss M, et al. Xenotransplantation of bovine bone marrow stromal cells into pig fetuses: Incorporation into skeletal muscle. Anim Biotech 2001;12(2):183-191.

Mikus J, Duff G, Krehbiel C, et al. Effects of an estradiol implant on locoweed consumption, toxicity, and recovery in growing beef steers. Prof Anim Scientist 2001;17:109-114.

Mostyn, A, Keisler D, Webb R, et al. The role of leptin in the transition from fetus to neonate. Proc Nutr Soc 2001;60:187-194.

Peters M, Smith M, Smith G. Use of critical interactive thinking exercises in teaching reproductive physiology to undergraduate students. J Anim Sci 2002;80:862-865.

Pru J, Rueda B, Austin K, et al. Interferon-tau suppresses PGF2a secretion independently of the mitogen activated protein kinase and nuclear factor k B pathways. Biol Reprod 2001;64:965-973.

Pru J, Austin K, Haas A, et al. Pregnancy and interferon-t upregulate gene expression of members of the 1-8 family in the bovine uterus. Biol Reprod 2001;65:1471-1480.

Regnault T, Galan H, Parker T, et al. Placental development in normal and compromised pregnancies. Placenta 2002;23:S119-129.

Regnault T, Orbus R, De Vrijer B, et al. Placental expression of VEGF, PlGF and their receptors in a model of placental insufficiency-intrauterine growth restriction (PI-IUGR). Placenta 2002;23:132-144.

Ricke W, Smith G, Smith M. Matrix metalloproteinase expression and activity following prostaglandin F2 alpha-induced luteolysis. Biol Reprod 2002;66:685-691.

Ricke W, Smith G, McIntush E, et al. Analysis of luteal tissue inhibitor of metalloproteinases (TIMP-1, -2, and 3) during prostaglandin F2 alpha-induced luteolysis. Biol Reprod 2002;66:1387-1394.

Ricke W, Smith G, Reynolds L, et al. Matrix metalloproteinase (2, 9, and 14) expression, localization and activity in ovine corpora lutea throughout the estrous cycle. Biol Reprod 2002;66:1083-1094.

Roberts A, Funston R, Moss G. Insulin-like growth factor binding proteins in the bovine anterior pituitary. Endocrine 2001;14:399-406.

Roberts A, Funston R, Moss G. Insulin-like growth factor binding proteins in the bovine anterior pituitary. Endocrine 2001;14: 399-406.

Rule D, Moss G, Snowder G, et al. Adipose tissue lipogenic enzyme activity, serum IGF-1, and IGF-binding proteins in the callipyge lamb. Sheep and Goat Research J 2002;17(2):39-46.

Sawyer H, Smith P, Heath D, et al. Formation of ovarian follicles during fetal development in sheep. Biol Reprod 2002;66:1134-1150.

Shirley K, Hernandez J, Hallford D, et al. Serum luteinizing hormone, growth hormone, and insulin-like growth factor-I after releasing hormone challenge in prepubertal ewe lambs selected for twinning. Theriogenology 2001;56:867-877.

Smith M, Ricke W, Bakke L, et al. Ovarian tissue remodeling: Role of matrix metalloproteinases and their inhibitors. Mol Cell Endo 2002;191:45-56.

Sosa J, Senger P, Reeves J. Evaluation of American Wagyu sires for scrotal circumference by age and body weight. J Anim Sci 2002;80:19-22.

Stellflug J, Wulster-Radcliffe M, Hensley E, et al. Oxytocin-induced cervical dilation and cervical manipulation in sheep: Effects on laparoscopic artificial insemination. J Anim Sci 2001;79:568-573.

Stellflug J, Hatfield P, Wulster-Radcliffe M. Reproductive performance of ewe lambs from ewes from different selection practices with or without induced estrus. Anim Reprod Sci 2001;66:185-193.

Suwannaroj S, Lagoo A, Keisler D, et al. Antioxidants suppress mortality in the female NZB x NZW F1 mouse model of systemic lupus erythematosus (SLE). Lupus 2001;10:258-65

Thatcher W, Guzeloglu A, Mattos R, et al. Uterine-conceptus interactions and reproductive failure in cattle. Theriogenology 2001;56:1435-1450.

Thomas M, Enns R, Hallford D, et al. Relationships of metabolic hormones and serum glucose to growth and reproductive development in performance-tested Angus, Brangus, and Brahman bulls. J Anim Sci 2002;80:757-767.

Ulker H, Gant B, deAvila D, et al. LHRH antagonist decreases LH and P4 secretion but does not alter length of estrous cycle in heifers. J Anim Sci 2001;79:2902-2907.

Ulker H, Kanter M, Gohdal O, et al. The effect of recombinant LHRH fusion proteins on testicular development and histology in ram lambs. Deutche Tierarztliche Wochenschrift 2001;108:459-464.

Weber P, Madsen S, Smith G, et al. Pre-translational regulation of neutrophil L-selectin in glucocorticoid challenged cattle. Vet Immunol Immunopathol 2001;83:213-240.

Weems Y, Bridges P, Sasser R, et al. Effects of an aromatase inhibitor (CGS 16949A) on secretion of estradiol-17 beta, pregnancy specific protein B(PSPB), P4, and prostaglandins E and F2 alpha (PGE2;PGF2 alpha) in 90-day ovariectomized pregnant sheep. PGs & Other Lipid Med 2001;66:77-87.

Wells N, Hallford D, Hernandez J, et al. Use of calcium sulfate to alleviate signs of copper toxicosis in ewe lambs. Bov Prac 2001;35(1):70-72.

Wulster-Radcliffe M, Williams M, Stellflug J, et al. Technical note: Artificial vagina vs a vaginal collection vial for collecting semen from rams. J Anim Sci 2001;79:2964-2967.

Yankey S, Hicks B, Carnahan K, et al. Expression of the antiviral protein Mx in peripheral blood mononuclear cells of pregnant and bred, non-pregnant ewes. J Endo 2001;170, R7-R11.

Yankey S, Hicks B, Carnahan K, et al. Expression of the antiviral protein Mx in peripheral blood mononuclear cells of pregnant and bred, non-pregnant ewes. J Endo 2001;170:R7-R11.