RESUMO
The objective was to evaluate the effect of equine chorionic gonadotropin (eCG) and hCG post artificial insemination (AI) on fertility of lactating dairy cows. In Experiment 1, cows were either treated with eCG on Day 22 post AI (400 IU; n = 80) or left untreated (n = 84). On Day 29, pregnant cows were either treated with hCG (2500 IU; n = 32) or left untreated (n = 36). Pregnancy and progesterone were evaluated on Days 29 and 45. In Experiment 2, cows (n = 28) were either treated with eCG on Day 22 (n = 13) or left untreated (n = 15) and either treated with hCG on Day 29 (n = 14) or left untreated (n = 14). Blood sampling and ultrasonography were conducted between Days 22 and 45. In Experiment 3, cows were either treated with eCG on Day 22 post AI (n = 229) or left untreated (n = 241). Pregnancy was evaluated on Days 36 and 85. In Experiment 1, eCG on Day 22 increased (P < 0.02) the number of pregnant cows on Day 29 (50.0 vs. 33.3%) and on Day 45, the increase was higher (P < 0.01) in cows with timed AI (41.2 vs. 6.5%) than in cows AI at detected estrus (50.0 vs. 37.8%). Pregnancy losses were reduced by eCG and hCG, but increased in cows that did not receive eCG but were given hCG (P < 0.01). Treatment with hCG tended (P < 0.06) to increase progesterone in control cows, but not in cows treated with eCG. In Experiment 2, hCG increased (P < 0.01) the number of accessory CLs on Day 35 (28.5 vs. 0.0%) and tended (P < 0.07) to increase progesterone. In Experiment 3, eCG increased the number of pregnant cows (P < 0.05) on Days 36 and 85, but only in cows with low body condition (eCG = 45.6 and 43.5%; Control = 22.9 and 22.9%). In conclusion, eCG at 22 days post insemination increased fertility, primarily in cows with low body condition and reduced pregnancy losses when given 7 days before hCG; hCG induced accessory CLs and slightly increased progesterone, but hCG given in the absence of a prior eCG treatment reduced fertility.
Assuntos
Bovinos/fisiologia , Gonadotropina Coriônica/farmacologia , Fármacos para a Fertilidade Feminina/farmacologia , Inseminação Artificial/veterinária , Lactação , Animais , Gonadotropina Coriônica/administração & dosagem , Feminino , Fármacos para a Fertilidade Feminina/administração & dosagem , Cavalos , Humanos , GravidezRESUMO
Reproduction continues to be a critical component to maintain a dairy farm economically viable. For every farm and for every cow, there is an optimum time for pregnancy, which is mostly influenced by level of production, persistency of lactation, and parity. In general, as production decreases, lactation number increases, and persistency of lactation decreases, cows should be bred sooner postpartum and pregnancy obtained early in lactation. The voluntary waiting period is determined based on the desired interval postpartum to pregnancy and the pregnancy rate of the farm. As pregnancy rates increase, the voluntary waiting period can be delayed, particularly when milk production is high. Studies in the literature have compared several breeding strategies to obtain a pregnant cow. In general, pregnancies obtained by artificial insemination are cheaper than those originated by natural service. The major reason is that AI programs result in similar or better reproductive performance and are cheaper to implement than natural service programs because of the high costs of acquiring and feeding bulls. Within the AI program, those that incorporate timed AI for first insemination followed by detection of estrus result in lowest median days open and more profit per cow, and the benefits of improving reproduction are greater when milk prices ar e low. The use of embryo technologies as a breeding program for lactating dairy cows, with the aim to improve reproductive performance, is only attractive when the differential in fertility relative to AI is large. In most cases, AI programs have to result in very poor fertility (<15%) for the typical results from embryo transfer (40-45% pregnancy) to be economically attractive at current costs. For dairy heifers, there is littl e justification to incorporate timed AI programs when detection of estrus is excellent, above 70%; however, for farms with detection of estrus below 60%, either timed AI for first AI followed by detection of estrus or timed AI alone improve reproductive performance and reduce the cost per pregnancy.(AU)
Assuntos
Animais , Bovinos , Prenhez/metabolismo , Embriologia/métodos , Ração Animal , Bovinos/classificação , Inseminação Artificial/veterináriaRESUMO
During early postpartum, high-producing dairy cows undergo a period of extensive tissue catabolism because of negative nutrien t balance. Homeorrhetic controls assure that nutrients are partitioned to favor lactation at the same time that homeostasis secures survival. However, unrestrained metabolic disturbances often lead to diseases which, in turn, dramatically decrease both productive and reproductive performance. Negative nutrient balance ha s been associated with compromised immune and reproductive functions in dairy cows. Low circulating concentrations of glucose and insulin associated with elevated concentrations of non-esterified fatty acids and ketone bodies postpartum have disruptive and detrimental effects on the oocyte, granulosa and immune cells. Negative nutrient balance is associated with changes in the pattern of ovarian follicle growth which can indirectly affect oocyte quality. Some of this disruption seems to be the result of endocrine and biochemical changes that alter the micro- environment of the growing and maturing oocyte. In addition, cows under negative nutrient balance have extended periods of anovulation. Postpartum anestrus, as well as infertility, is magnified by losses of body condition during the early postpartum period. The underlying mechanism for resumption of ovulatory cycles seems to be associated with metabolic signals and regulatory hormones primarily insulin and insulin- like growth factor (IGF)-1, which link nutritional status with gonadotropin secretion, recoupling of the growth hormone-IGF system, and follicle maturation and ovulation. Feeding diets th at promote increases in plasma glucose and insulin may improve the metabolic and endocrine status of cows in early lactation. Furthermore, fertility in postpartum cows is also determined by uterine health. Reductions in circulating concentrations of Ca and antioxidant vitamins around parturition are also linked with impaired immune competence and result in greater risk of uterine diseases that impair reproduction. Specific nutrients and dietary ingredients have been implicated to affect reproduction in cattle. Excess intake of dietary protein has been suggested as detrimental to fertility, although feeding excess of dietary protein can no longer be justified. Addition of moderate amounts of supplemental fat to the diet improves caloric intake, modulates prostaglandin F2 secretion by the uterus, affects ovarian dynamics, enhances luteal function and embryo quality, and has moderate positive effects on fertility. More specifically, some fatty acids might impact fertilization rate and embryo quality in dairy cows. On the contrary, some dietary ingredients, such as gossypol, when ingested in large quantities decrease fertility of dairy cows because of its negative effects on embryo quality and pregnancy maintenance.(AU)
Assuntos
Animais , Metabolismo/fisiologia , Homeostase/fisiologia , Oócitos/citologia , Dieta , Bovinos/classificação , Ciências da Nutrição AnimalRESUMO
During early postpartum, high-producing dairy cows undergo a period of extensive tissue catabolism because of negative nutrien t balance. Homeorrhetic controls assure that nutrients are partitioned to favor lactation at the same time that homeostasis secures survival. However, unrestrained metabolic disturbances often lead to diseases which, in turn, dramatically decrease both productive and reproductive performance. Negative nutrient balance ha s been associated with compromised immune and reproductive functions in dairy cows. Low circulating concentrations of glucose and insulin associated with elevated concentrations of non-esterified fatty acids and ketone bodies postpartum have disruptive and detrimental effects on the oocyte, granulosa and immune cells. Negative nutrient balance is associated with changes in the pattern of ovarian follicle growth which can indirectly affect oocyte quality. Some of this disruption seems to be the result of endocrine and biochemical changes that alter the micro- environment of the growing and maturing oocyte. In addition, cows under negative nutrient balance have extended periods of anovulation. Postpartum anestrus, as well as infertility, is magnified by losses of body condition during the early postpartum period. The underlying mechanism for resumption of ovulatory cycles seems to be associated with metabolic signals and regulatory hormones primarily insulin and insulin- like growth factor (IGF)-1, which link nutritional status with gonadotropin secretion, recoupling of the growth hormone-IGF system, and follicle maturation and ovulation. Feeding diets th at promote increases in plasma glucose and insulin may improve the metabolic and endocrine status of cows in early lactation. Furthermore, fertility in postpartum cows is also determined by uterine health. Reductions in circulating concentrations of Ca and antioxidant vitamins around parturition are also linked with impaired immune competence and result in greater risk of uterine diseases that impair reproduction. Specific nutrients and dietary ingredients have been implicated to affect reproduction in cattle. Excess intake of dietary protein has been suggested as detrimental to fertility, although feeding excess of dietary protein can no longer be justified. Addition of moderate amounts of supplemental fat to the diet improves caloric intake, modulates prostaglandin F2 secretion by the uterus, affects ovarian dynamics, enhances luteal function and embryo quality, and has moderate positive effects on fertility. More specifically, some fatty acids might impact fertilization rate and embryo quality in dairy cows. On the contrary, some dietary ingredients, such as gossypol, when ingested in large quantities decrease fertility of dairy cows because of its negative effects on embryo quality and pregnancy maintenance.
Assuntos
Animais , Dieta , Homeostase/fisiologia , Metabolismo/fisiologia , Oócitos/citologia , Bovinos/classificação , Ciências da Nutrição AnimalRESUMO
Reproduction continues to be a critical component to maintain a dairy farm economically viable. For every farm and for every cow, there is an optimum time for pregnancy, which is mostly influenced by level of production, persistency of lactation, and parity. In general, as production decreases, lactation number increases, and persistency of lactation decreases, cows should be bred sooner postpartum and pregnancy obtained early in lactation. The voluntary waiting period is determined based on the desired interval postpartum to pregnancy and the pregnancy rate of the farm. As pregnancy rates increase, the voluntary waiting period can be delayed, particularly when milk production is high. Studies in the literature have compared several breeding strategies to obtain a pregnant cow. In general, pregnancies obtained by artificial insemination are cheaper than those originated by natural service. The major reason is that AI programs result in similar or better reproductive performance and are cheaper to implement than natural service programs because of the high costs of acquiring and feeding bulls. Within the AI program, those that incorporate timed AI for first insemination followed by detection of estrus result in lowest median days open and more profit per cow, and the benefits of improving reproduction are greater when milk prices ar e low. The use of embryo technologies as a breeding program for lactating dairy cows, with the aim to improve reproductive performance, is only attractive when the differential in fertility relative to AI is large. In most cases, AI programs have to result in very poor fertility (<15%) for the typical results from embryo transfer (40-45% pregnancy) to be economically attractive at current costs. For dairy heifers, there is littl e justification to incorporate timed AI programs when detection of estrus is excellent, above 70%; however, for farms with detection of estrus below 60%, either timed AI for first AI followed by detection of estrus or timed AI alone improve reproductive performance and reduce the cost per pregnancy.
Assuntos
Animais , Bovinos , Embriologia/métodos , Prenhez/metabolismo , Ração Animal , Bovinos/classificação , Inseminação Artificial/veterináriaRESUMO
Pregnancy per artificial insemination (AI) was evaluated in dairy cows (Bos taurus) subjected to synchronization and resynchronization for timed AI (TAI). Cows (n=718) received prostaglandin F(2alpha) (PGF) on Days -38 and -24 (Days 39 and 53 postpartum), gonadotropin-releasing hormone (GnRH) on Day -10, PGF on Day -3, and GnRH and TAI on Day 0. Between Days -10 and -3, cows received a progesterone intravaginal insert (CIDR group) or no CIDR (Control group). Between Days 14 and 23, cows received a CIDR (Resynch CIDR group) or no CIDR (Resynch control group), GnRH on Day 23, with pregnancy diagnosis on Day 30. Cows in estrus (between Days 0 and 30) were re-inseminated at detected estrus (RIDE). Nonpregnant cows received PGF on Day 30 and GnRH and TAI on Day 33. Plasma progesterone was determined to be low or high on Days -24 and -10. Pregnancy rates were evaluated 30 and 55 d after AI. The CIDR insert included in the Presynch-Ovsynch protocol did not increase overall pregnancy per AI for first service (36.1% and 33.6% for CIDR; 34.1% and 28.8% for Control) but did decrease pregnancy loss (7.0% for CIDR and 15.6% for Control). The CIDR insert increased pregnancy per AI in cows with high progesterone at the time the CIDR insert was applied. Administration of a CIDR insert between Days 14 and 23 of the estrous cycle after first service did not increase overall pregnancy per AI to second service (24.7% and 22.7% for Resynch CIDR; 28.6% and 25.3% for Resynch control). For second service, RIDE cows had lower pregnancy rates in the Resynch CIDR group than in the Resynch control group. Cows with a CL (corpus luteum) at Day 30 had higher pregnancy rates in the Resynch CIDR group than those in the Resynch control group.
Assuntos
Bovinos/fisiologia , Inseminação Artificial/métodos , Lactação , Animais , Ciclo Estral , Feminino , Hormônio Liberador de Gonadotropina/farmacologia , Gravidez , Taxa de Gravidez , Progesterona/administração & dosagem , Progesterona/sangue , Progesterona/farmacologia , Prostaglandinas/farmacologiaRESUMO
To evaluate the effects of incorporating medroxyprogesterone acetate (MAP) in an Ovsynch protocol, cyclic lactating dairy cows were assigned randomly to two groups (control and MAP, n=8 each). Ovsynch treatment (Day 0: GnRH, Day 7: PG, Day 9: GnRH) was initiated at random stages of the estrous cycle (control) and an intravaginal polyurethane sponge impregnated with 300mg of MAP was inserted intravaginally in the MAP group at Day 0 and removed at Day 7 of the Ovsynch protocol (MAP treatment). Ovaries were scanned daily from Day 0 until the second GnRH treatment on Day 9 and from then every 6h for 36 h. Milk samples were collected three times weekly starting 17 days before the initiation of treatment to determine the stage of the cycle at the beginning of the Ovsynch protocol. Blood samples were collected to monitor estradiol (E2), progesterone (P4), LH, and 15-ketodihydro-PGF(2alpha) (PGFM) by RIA. Response to the first GnRH treatment varied with the stage of the cycle at the time of initiation of treatment, as cows in metestrous and late diestrous did not ovulate. In cows ovulating, growth rate of the new follicle was not affected by the addition of MAP. No treatment differences were found in E2 concentrations which reached a maximum at Day 9, consistent with the maximum follicular size. At Day 7, cows with luteal concentrations of P4 had increased concentrations of PGFM, but cows with basal P4 did not show an active release of prostaglandins. There were no treatment differences in the ovulatory response to the second GnRH-induced ovulation, with 11 of the 16 cows ovulating between 16 and 32 h. The addition of MAP to the Ovsynch protocol could not mimic the normal high progesterone levels needed to prevent premature ovulations in those cows with premature CL regression.
Assuntos
Bovinos/fisiologia , Dinoprosta/análogos & derivados , Hormônio Liberador de Gonadotropina/administração & dosagem , Hormônios/sangue , Lactação , Acetato de Medroxiprogesterona/administração & dosagem , Folículo Ovariano/fisiologia , Prostaglandinas F Sintéticas/administração & dosagem , Administração Intravaginal , Animais , Dinoprosta/sangue , Estradiol/sangue , Ciclo Estral , Feminino , Cinética , Hormônio Luteinizante/sangue , Indução da Ovulação/veterinária , Progesterona/sangueRESUMO
During early pregnancy, a "critical period" may be defined between Days 15 and 17. Embryonic mortality associated with this period causes significant economic losses to the cattle industry. During this period, the endometrium will follow a default program to release luteolytic pulses of PGF2alpha, unless the conceptus sends appropriate antiluteolytic signals to block PGF2alpha, production. Maintenance of pregnancy is dependent on a successful blockage of endometrial PGF2alpha production. Biology of the critical period is complex and multifactorial. Endocrine, cellular and molecular factors, both from maternal and conceptus origins act in concert to determine whether luteolysis or maintenance of pregnancy will prevail. Understanding the influences of such factors in the biology of the critical period allowed researchers to produce a series of strategies aiming to favor maintenance of pregnancy in lieu of luteolysis. Strategies include hormonal and nutritional manipulations to decrease plasma concentrations of estradiol 17beta (E2) while increasing those of progesterone (P4), and inhibiting the PGF2alpha-synthesizing enzymatic machinery in the endometrium during the critical period. Experimental results indicate that use of such strategies has improved pregnancy rates following artificial insemination and embryo transfer programs.
Assuntos
Bovinos/fisiologia , Corpo Lúteo/metabolismo , Dinoprosta/metabolismo , Endométrio/metabolismo , Resultado da Gravidez/veterinária , Prenhez/fisiologia , Animais , Transferência Embrionária/veterinária , Endométrio/citologia , Estradiol/sangue , Feminino , Fertilidade , Fertilização in vitro/veterinária , Fase Luteal/sangue , Gravidez , Taxa de Gravidez , Progesterona/sangueRESUMO
Our objective was to evaluate the effect of excessive intake of ruminally degradable crude protein [11.1 and 15.7% of dietary dry matter (DM)] and supplemental fat (Ca salts of long-chain fatty acids at 0 or 2.2% of dietary DM) on the productive performance of lactating Holstein cows (n = 45) during the first 120 d postpartum. The main N sources were soybean meal and urea in the diets with high concentrations of degradable protein versus a combination of vegetable and animal by-product feedstuffs in the diets with less degradable protein. Cows fed the diets with excess degradable protein had slower rates of increase in DM intake (DMI) and milk production, had lower plasma insulin and greater plasma glucose and urea concentrations, and lost more than twice the body weight of cows fed the diets with less degradable protein. Supplemental fat in the highly degradable protein diet reduced the loss of body condition, stimulated DMI, and reduced concentrations of plasma nonesterified fatty acids early postpartum compared with the highly degradable protein diet without added fat. Without affecting DMI, supplemental fat stimulated milk production (2 kg/d) starting at 3 wk postpartum. During early lactation, DMI and milk production were sensitive to the degree of ruminal degradability of protein and energy supplementation in the form of fat.
Assuntos
Cálcio/administração & dosagem , Bovinos/fisiologia , Dieta , Proteínas Alimentares/metabolismo , Ácidos Graxos/administração & dosagem , Lactação , Amônia/sangue , Ração Animal , Animais , Composição Corporal , Peso Corporal , Proteínas Alimentares/administração & dosagem , Digestão , Feminino , Insulina/sangue , Lipídeos/sangue , Leite/química , Rúmen/metabolismo , Glycine max , Ureia/administração & dosagem , Ureia/sangueRESUMO
Multiparous Holstein cows (n = 45) were assigned at calving to one of four diets arranged in a 2 x 2 factorial design. The two main factors were dietary concentration (dry matter basis) of 1) degradable intake protein (11.1 or 15.7%) and 2) supplemental fat (Ca salts of long-chain fatty acids; 0 or 2.2%). Soybean meal and urea were replaced with less degradable protein meals (corn gluten meal, meat and bone meal, fish meal, and blood meal). During the first 9 wk postpartum, cows fed diets containing the greater concentration of highly degradable protein demonstrated less follicular development on their ovaries, were delayed in their first luteal activity postpartum (25.2 vs. 38.6 d), accumulated less luteal tissue (< 15 vs. > 70 mm), and had lower plasma progesterone accumulated over time. The supplementation of Ca salts of long-chain fatty acids to the 15.7% degradable protein diet doubled the number of corpora lutea, reduced time to first rise in progesterone by 6 d, doubled the number of normal luteal phases, and restored the pattern of accumulated plasma progesterone concentrations to a pattern that was similar to that induced by other diets. Cows were synchronized to estrus and inseminated at approximately 65 d postpartum. Pregnancy rate was increased from 52.3 to 86.4% when fat was supplemented. Cows fed fat tended to have more corpora lutea and a larger corpus luteum and accumulated more plasma progesterone than did cows not fed fat. Diets containing excess degradable protein or Ca salts of long-chain fatty acids influenced ovarian structures and reproductive performance.
Assuntos
Cálcio/administração & dosagem , Bovinos/fisiologia , Proteínas Alimentares/metabolismo , Ácidos Graxos/administração & dosagem , Lactação/fisiologia , Reprodução/fisiologia , Animais , Colo do Útero/fisiologia , Proteínas Alimentares/administração & dosagem , Digestão , Estro , Feminino , Fertilização , Folículo Ovariano/fisiologia , Palpação , Gravidez , Reto , Útero/fisiologiaRESUMO
Bovine interferon-alpha I1 (bIFN-alpha) may be useful for enhancing fertility in sheep and cattle because it has extensive sequence homology with ovine and bovine trophoblast protein-1 and, like those proteins, extends corpus luteum lifespan. To test the effectiveness of bIFN-alpha to enhance fertility, several experiments were performed in which inseminated heifers were given i.m. injections of bIFN-alpha approximately at the time of embryo-mediated signals that result in maintenance of the corpus luteum. In Exp. 1, heifers given 20 mg of bIFN-alpha daily from d 14 to 17 tended (P less than .07) to have lower pregnancy rates at d 110 to 112 of gestation (36/75; 48% vs 43/72; 60%). Similar results were obtained in Exp. 2 when heifers received a single injection of 40 mg of bIFN-alpha or placebo at d 13 after estrus; pregnancy rates at d 42 were 39/104 (38%) for bIFN-alpha and 47/98 (48%) for placebo. In Exp. 3, heifers were given gradually increasing doses of bIFN-alpha or placebo from d 11 to 19, because such a regimen had been shown to reduce the number of heifers experiencing hyperthermia after bIFN-alpha injection. Pregnancy rates were 42/95 (44%) for bIFN-alpha and 62/111 (56%) for placebo. Across all three experiments, pregnancy rates were lower (P less than .01) for heifers treated with bIFN-alpha (117/274; 43%) than for heifers treated with placebo (152/281; 54%). In conclusion, these results demonstrate that, under the administration systems used, bIFN-alpha does not increase pregnancy rate, but rather tends to reduce it.
Assuntos
Bovinos/fisiologia , Estro/efeitos dos fármacos , Fertilidade/efeitos dos fármacos , Fertilização/efeitos dos fármacos , Interferon Tipo I/farmacologia , Animais , Temperatura Corporal/efeitos dos fármacos , Método Duplo-Cego , Feminino , Gravidez , Distribuição Aleatória , Proteínas RecombinantesRESUMO
Experiments were performed to determine the mechanism by which recombinant bovine interferon-alpha I1 (rbIFN-alpha) causes an acute reduction in plasma concentrations of progesterone. In experiment 1, administration of a prostaglandin synthesis inhibitor blocked rbIFN-alpha-induced hyperthermia but did not prevent the decline in plasma concentrations of progesterone. The decline in progesterone concentrations caused by rbIFN-alpha was, therefore, not a direct consequence of the associated hyperthermia or of pathways mediated through prostaglandin synthesis. It is also unlikely that rbIFN-alpha acts to increase the clearance of progesterone since injection of rbIFN-alpha did not decrease plasma concentrations of progesterone in ovariectomized cows given an intravaginal implant of progesterone (experiment 2). In experiment 3, rbIFN-alpha did not affect basal and LH-induced release of progesterone from cultured luteal slices, indicating that rbIFN-alpha is unlikely to affect luteal function directly. Injection of rbIFN-alpha did, however, cause a decrease in plasma concentrations of LH in ovariectomized cows (experiment 4) that coincided temporally with the decrease in progesterone concentrations seen in cows having a functional corpus luteum. The present results strongly suggest that rbIFN-alpha acts to reduce secretion of progesterone by interfering with pituitary support for luteal synthesis of progesterone. The finding that rbIFN-alpha can inhibit LH secretion implies that interferon-alpha molecules should be considered among the cytokines that can regulate hypothalamic or pituitary function.
Assuntos
Temperatura Corporal/efeitos dos fármacos , Bovinos/fisiologia , Interferon Tipo I/farmacologia , Células Lúteas/efeitos dos fármacos , Progesterona/sangue , Animais , Feminino , Hormônio Luteinizante/metabolismo , Hormônio Luteinizante/fisiologia , Progesterona/metabolismo , Proteínas RecombinantesRESUMO
Experiments were performed to (1) verify the inhibitory effect of bovine trophoblast protein-1 (bTP-1) on uterine prostaglandin synthesis, (2) evaluate whether other interferon-alpha (IFN-alpha) molecules also inhibit prostaglandin secretion, and (3) test whether the enzyme 2',5'-oligoadenylate synthetase (2-5A synthetase) can be induced in endometrium by interferon-alpha. In experiment 1, all interferon molecules (bTP-1, oTP-1, bIFN-alpha and hIFN-alpha) equally inhibited secretion of PGF and PGE2 from endometrial explant cultures obtained at day 17 of the estrous cycle. In experiment 2, endometrial explants obtained from day 17 of the cycle were cultured with and without bovine serum albumin (BSA; 50 micrograms/ml) and bIFN-alpha (0, 0.84, 4.2, and 42 nM). Addition of BSA to the culture medium greatly enhanced the accumulation of PGF into the medium. The bIFN-alpha inhibited accumulation of PGF and PGE2 in both the presence or absence of BSA by 12 h. All three concentrations of bIFN-alpha were equally effective in inhibiting prostaglandin accumulation. Additionally, all concentrations of bIFN-alpha increased the amounts of 2-5A synthetase in endometrium. In conclusion, these results confirm the inhibitory effect of bTP-1 on PGF release from endometrium and demonstrate that bTP-1 can also inhibit PGE2 secretion. Furthermore, other interferon-alpha molecules, including bIFN-alpha, hIFN-alpha, and oTP-1, also reduced PGF and PGE2 secretion in culture. It is likely, therefore, that conceptus and other interferon-alpha molecules exert similar effects on endometrium in vitro and that the antiluteolytic effects of bIFN-alpha in vivo are mediated in part by changes in endometrial prostaglandin synthesis.