Intracellular regulation of endometrial PGF(2a) and PGE(2) production in dairy cows during early pregnancy and following treatment with recombinant interferon-tau.

Objectives were to examine how the conceptus and recombinant bovine interferon-tau (rbIFN-tau) regulate intracellular components of the PGF(2a) synthetic pathway and to determine if arachidonic acid (AA) is limiting in endometrial tissue of pregnant cows. In Experiment 1, uteri were collected from either cyclic or pregnant dairy cows on Day 17 post-estrus. Intercaruncular explants were dissected and incubated for 60 min to quantify PGF(2a) production in response to oxytocin (10(-6) M), A23187 (10(-5) M), melittin (10(-5) M), and phorbol 12, 13 dibutyrate (PDBu, 10(-6) M). Additional explants from the same cows were incubated for 24 h with and without AA. Oxytocin and A23187 did not stimulate PGF(2a) in explants from either cyclic or pregnant cows. Both PDBu, melittin, and A23187 + melittin stimulated PGF(2a) production in explants of cyclic cows, but not in explants of pregnant cows. The addition of AA to explant cultures for 24 hr did not increase PGF(2a) production during a subsequent 60-min incubation. In Experiment 2, explants were collected from cows that received intrauterine infusions of either BSA (1.9 mg/1.2 ml) or rbIFN-tau (0.2 mg rbIFN-tau + 1.7 mg BSA/1.2 ml) twice a day from Days 14 to 17 of the estrous cycle. Treatments of rbIFN-tau attenuated PGF(2a) secretion induced by in vitro PDBu and A23187 treatments. However, rbIFN-tau treatment in vivo had no effect on the in vitro induction of PGF(2a) secretion by melittin. IFN-tau may regulate the PGF(2a) synthetic pathway by reducing activity of PKC or PKC mediated events.

Technical note: Application of the Box-Cox data transformation to animal science experiments.

In the use of ANOVA for hypothesis testing in animal science experiments, the assumption of homogeneity of errors often is violated because of scale effects and the nature of the measurements. We demonstrate a method for transforming data so that the assumptions of ANOVA are met (or violated to a lesser degree) and apply it in analysis of data from a physiology experiment. Our study examined whether melatonin implantation would affect progesterone secretion in cycling pony mares. Overall treatment variances were greater in the melatonin-treated group, and several common transformation procedures failed. Application of the Box-Cox transformation algorithm reduced the heterogeneity of error and permitted the assumption of equal variance to be met.

Milk plasmin during bovine mammary involution that has been accelerated by estrogen.

The purpose of this study was to evaluate whether the plasminogen and plasmin system within bovine mammary secretions was influenced by an estrogen treatment that was used to accelerate mammary tissue involution. Holstein cows were injected with 4 ml of ethanol excipient (n = 21) or 15 mg of estradiol-17 beta (n = 23) on each of the 4 d that preceded final milk removal. Dates of final milk removal (d 0) were designated as 60 d prior to expected dates of calving. Each mammary quarter was sampled once to collect secretions that corresponded to d 0, 3, 11, and 25 or d 1, 7, 18, and 30 of the dry period. Concentrations of plasminogen, plasmin, and somatic cells in secretions increased earlier for treated cows than for control cows. The ratio of plasminogen to plasmin in secretions decreased earlier for treated cows than for control cows. These responses support the suggestion that the plasminogen and plasmin system is involved in the involution of bovine mammary tissue. Estrogen treatment increased the activation of plasminogen, which was evidenced by a precipitous decrease in the ratio of plasminogen to plasmin that occurred as concentrations of plasminogen and plasmin increased. The activation of plasminogen likely contributed to the increased rate of mammary tissue involution that was effected by exogenous estrogen. Endogenous estrogen secreted by the developing fetal and placental unit might mediate, in part, the gradual involution that occurs during lactation.

Factors affecting human placenta and birth weights and vitality of newborns in a subtropical environment

Os fatores que afetam o peso de nascimento e da placenta e a vitalidade de recém-nascidos humanos na Flórida foram avaliados em bancos de dados de 1480 (conjunto de dados I) e 788 (conjunto de dados II) casos. Este último conjunto foi uma subdivisäo do primeiro, tendo menos casos devido a procedimentos de seleçäo mais rígidos. Estes procedimentos excluíram natimortos ou fetos com valores muito elevados ou baixos em qualquer variável de resposta, sendo que estes últimos foram entäo considerados como casos anormais. Os fatores avaliados afetaram significativamente as variáveis de resposta na maioria dos casos, mas näo necessariamente em ambos os conjuntos de dados. No conjunto de dados II, efeitos do mês do parto foram detectados em todas as variáveis exceto vitalidade aos 5 min. pós- parto (valor II de Apgar). O peso da placenta foi 112g menor nos meses quentes do que nos meses frios. A vitalidade em 1 min. pós-parto (valor I de Apgar) foi afetada pelo mês mas näo de modo sistemático. Os recém-nascidos do sexo masculino tiveram pesos 45g maiores para placenta, para peso corporal (142g) e para peso total (187g). O grupo étnico afetou todas as respostas, exceto o peso placentário. Efeitos da paridade foram detectados para todas as respostas, exceto peso placentário e valor II de Apgar; a duraçäo da gestaçäo afetou todas as respostas, exceto o peso placentário. Os pesos placentário e do recém nascido correlacionaram-se intensamente com sua soma (correlaçäo de parte com o todo), mas näo um com o outro nem com os valores de Apgar. Estes correlacionaram-se intensamente um com o outro. O conhecimento das características das variáveis de resposta e dos fatores que as influenciam deve contribuir consideravelmente para o conhecimento geral dos fatores que afetam as características dos nascimentos humanos.

Estrogen administered at final milk removal accelerates involution of bovine mammary gland.

To evaluate whether estrogen hastened involution of mammary tissue, Holstein cows were injected with 4 ml of ethanol excipient (n = 21) or 15 mg of estradiol-17 beta (n = 23) on each of the 4 d that preceded final milk removal. Dates of final milk removal (d 0) were designated as 60 d prior to expected dates of calving. Milk volumes were recorded, and samples were collected prior to the first and fourth injections. During the dry period, each mammary quarter within the cow was sampled once to collect secretions on dates that corresponded to d 0, 3, 11, and 25 or 1, 7, 18, and 30 of the dry period. Milk synthesis and secretion declined abruptly because of treatment. The decreased concentrations of alpha-lactalbumin, lactose, citrate, and potassium in secretions of controls, as well as the increased somatic cells, protein, lactoferrin, and sodium, occurred earlier in secretions from treated cows. These shifts of approximately 6 d, relative to days dry, suggested that exogenous estradiol increased the involution rate of mammary tissue.

Technical note: subjective enumeration of episodic events (spikes) in animal physiology experiments.

Blood samples of nine sheep were taken over time and analyzed for estrone, estradiol, and progesterone. Results were plotted for each sheep, and graphs were evaluated by 26 evaluators with various previous experience. Sheep were sampled for different time periods. Repeatabilities for the number of spikes of estrone, estradiol, and progesterone recorded for sheep were variable, ranging from .019 to .547. Repeatabilities for evaluators ranged from .033 to .427, but these values decreased to < .001 to .030 when adjusted by covariance for the number of spikes possible. Results indicated that either an objective procedure for counting spikes should be used in comparable research or that evaluators should be trained in visual counting procedures to improve their repeatability.

Effects of steroid administration on pituitary luteinizing hormone and follicle-stimulating hormone in ovariectomized pony mares in the early spring: pituitary responsiveness to gonadotropin-releasing hormone and pituitary gonadotropin content.

These experiments tested the hypothesis that administration of steroid hormones to ovariectomized (OVX) mares during the vernal transition to the breeding season would influence LH and FSH secretion. Circulating gonadotropin concentrations, response to exogenous GnRH, and pituitary gonadotropin content were monitored. Experiments 1 and 2 were conducted, beginning 10 March, and 3 February, respectively, utilizing a total of 30 long-term OVX pony mares. In experiment 1, mares were administered vehicle (n = 5) or estradiol-17 beta (E2, n = 5, 5 mg/3 ml sesame oil), twice daily for 16 days. Blood samples were collected daily for assessment of circulating LH and FSH concentrations. On Day 10 of treatment, 400 micrograms GnRH were administered to all mares. LH increased significantly over days of treatment in the estradiol-treated group, but pituitary response to GnRH tended to be less than in control mares. Circulating FSH tended to decline over days of treatment in estradiol-treated mares, and the pituitary response to GnRH was significantly reduced. Pituitary LH, but not FSH, was increased on Day 16 of treatment with estradiol. In experiment 2, 20 OVX mares received, twice daily, vehicle (n = 5), E2, n = 5; 5 mg), progesterone (P4, n = 5; 100 mg), or progesterone plus estradiol (P4/E2, n = 5; 100 + 5 mg). Treatment continued for 14 days. GnRH (100 micrograms) challenges were administered on Days 6 and 13 of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Restricted conceptus mobility results in failure of pregnancy maintenance in mares.

Cycling pony mares were bred and used to test the effect of restricted conceptus mobility on luteal maintenance (i.e. maternal recognition of pregnancy). In Experiment 1, uterine horns were ligated to restrict conceptus mobility to one uterine horn, Group 1; one horn plus the uterine body, Group 2; or one horn, the body and approximately 80% of the second horn, Group 3. Pregnancies were monitored with real-time ultrasonography. Four of five mares in Group 1 and two of four mares in Group 2 returned to estrus (Day 16.0 +/- 1.9 and 14.5 +/- 0.7, respectively) and subsequently lost the embryonic vesicles (Day 17.2 +/- 1.2 and 15.7 +/- 0.7, respectively). None of the four mares in Group 3 lost the vesicles. There was a significant effect of the interaction of treatment (amount of uterus available to the conceptus) and day on plasma progesterone (P) concentration (p less than 0.005). In Experiment 2, conceptus mobility was restricted to one uterine horn in two groups of mares, of which the second was treated with the synthetic progestin, Regu-Mate (allyl trenbolone). In the first group, each of three mares lost the vesicle (Day 17.3 +/- 4.3). In the second group, four of five mares maintained the pregnancies, indicating that pregnancy failure was due to the effects of declining P. These data indicate that restricted conceptus mobility results in luteolysis in the mare, and that the subsequent decline in P leads to embryonic death.(ABSTRACT TRUNCATED AT 250 WORDS)

Avulsion of the bovine prepuce from its attachment to the penile integument during semen collection with an artificial vagina.

Avulsion of the prepuce (AP) from the penile integument during intromission into an artificial vagina (AV) is the most common injury involving the penis and prepuce of bulls collected for the production of frozen semen at artificial insemination (AI) centers. We observed clinical cases at two AI centers. Because temporary loss of seminal collections from genetically superior bulls occurs and the possibility of impotency exists, the economical loss from AP is significant. Surgery, rather than a nonsurgical procedure, is the preferred method for repair of AP if the diagnosis occurs on the same day as the injury. After injury, seminal collection is avoided. The bull can then begin a conditioning program prior to returning to a normal semen collection schedule. A specific etiology for AP remains undetermined; however, many variables potentially involved in its occurrence are known. Bulls with good libido following 4 to 5 yr of sexual inactivity are particularly susceptible to AP. No genetic predisposition was observed. At present, we believe that AP is caused by many factors and that implementing preventive measures does help.

Induction of lactation: histological and biochemical development of mammary tissue and milk yields of cows injected with estradiol-17 beta and progesterone for 21 days.

Lactations were induced in nonpregnant, nonlactating dairy cows by subcutaneous injections of estradiol-17 beta and progesterone for 21 d (.10 and .25 mg/kg body weight/d) and dexamethasone (.028 mg/kg body weight/d) on d 31 to 34. Milking was initiated on d 35. Each cow was biopsied two or three times during the experiment with five to eight mammary tissue biopsies on d 0, 7, 14, 21, 28, 35, 49, and 130. Mammary tissue preinjection had abundant connective and adipose tissues with limited lobuloalveolar structures. Beginning on d 7, there was decreased stroma, increased epithelial cell area, increased lobuloalveolar architecture, plus the accumulation of intracellular and intraluminal secretions which were high in lipid droplets. From d 7 through 35, these changes were progressive although variable among cows. Changes in activities of enzymes and concentrations of ribonucleic acid and deoxyribonucleic acid were gradual during this time but essentially paralleled histological development. Tissue samples during lactation (d 49 and 130) showed increased histological and biochemical development; development was maximal for d 130 samples. Fourteen of 15 cows that lactated had mean daily yields of milk more than 5 kg and yields of milk of 12 cows with projected or actual 305-d lactations were 63.0% of that during their previous natural lactations. Reasons for less yields of milk and for varied patterns of tissue development were not identified nor explained by concentrations of several selected hormones in plasma.

Periparturient endocrine changes of conceptus and maternal units in Holstein heifers bearing genetically different conceptuses.

Holstein heifers (n = 21) were balanced across sires and assigned to three service-sire-breed groups in which heifers were inseminated artificially to either purebred Angus (n = 7), Holstein (n = 7) or Brahman (n = 7) bulls. Semen from four bulls was used for each service sire-breed group. Blood samples were collected from a jugular vein thrice weekly from d 160 to 265 of pregnancy, daily thereafter until 15 d postpartum, and then thrice weekly until d 60 postpartum. Concentrations of progesterone, estrone, estradiol, and estrone sulfate from 23 d prepartum to parturition, and of 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) from 2 d prepartum to d 15 postpartum were measured by radioimmunoassay. Heifers within the Brahman-service-sire group had longer gestations (P less than .05) than those of Holstein- or Angus-service-sire groups (285.0 vs 278.7), 279.0 d). Calf birth weight was lower (P less than .05) in Angus- than Holstein- and Brahman-service-sire groups (30.6 vs 36.1, 43.4 kg). Daily trends of prepartum maternal progesterone concentrations were approximately 1 ng/ml lower (P less than .01) in Angus- than Holstein- or Brahman-service-sire groups until luteolysis occurred. Heifers bearing crossbred Angus conceptuses had lower daily trends of prepartum estrogens concentrations (P less than .01), whereas heifers of the Holstein- and, even more dramatically, of the Brahman-service-sire groups had a higher magnitude and greater rise of plasma estrogens concentrations between d -10 and -1 prepartum (less than .01). Postpartum mean concentrations (P less than .05) and response curves of PGFM were lower (P less than .01) in the Angus- than in the Holstein- or Brahman-service-sire groups. Calf birth weights were correlated with least-squares means for maternal concentrations of prepartum estrone (r = .57), estradiol (r = .59) and estrone sulfate (r = .64) and postpartum maternal concentrations of PGFM (r = .56). Functional responses of the conceptus (e.g., estrogens) and maternal units (e.g., progesterone and PGFM) were influenced by conceptus genotype during the periparturient period.

Relationships between maternal hormones and weight of newborn sheep.

Intact and ovariectomized mixed-breed sheep were studied in chronic experiments during the last weeks of pregnancy. Measurements were made of the rate of uterine blood flow (ml/min and ml X min-1 X kg-1, combined weight of fetus, uterus, and placenta) and of arterial and uterine venous concentrations of progestagens, estrone, and estradiol. The birth weight of the lamb was directly related to mean maternal concentrations of estrone and estradiol and to the rate of progestagen release by the uterus and its contents (ng X ml-1 X kg-1), calculated by taking the product of the rate of blood flow and the arteriovenous progestagen difference. Ovariectomy altered the relationship between birth weight and progestagen release. Data suggest that rates of progestagen release both by the fetoplacental unit and by the ovary are proportional to the birth weight of the lamb.

Induction of lactation: comparison of injections of estradiol-17 beta and progesterone for 7 or 21 days on prolactin response to thyrotropin releasing hormone and milk yield in dairy cattle.

Subcutaneous injections of estradiol-17 beta and progesterone (.10 and .25 mg/kg of body weight) for 7 (group I) or 21 (II) days were used. Dexamethasone (.028 mg/kg of body weight per day) or adrenocorticotropin (200 IU per day) was injected into cows in each group on days 18 to 20 (I) or 32 to 34 (II). Additionally, 100 mug of thyrotropin releasing hormone was injected intravenously on days 1, 7, 17 (I) or 1, 7, and 31 (II). Milking was initiated on days 21 (I) or 35 (II). Overall 13 of 14 cows had mean daily yields of milk greater than 5 kg; 12 had 305-day lactations. Yields of milk in cows injected for 21 days were greater on day 1 and increased more rapidly until peak was reached at 10 wk; daily mean production throughout lactation was greater (14.3 versus 10.1 kg) than for cows injected for 7 days. Lactation curves pooled within cow within treatment differed. Concentrations of estradiol, estrone and progesterone increased during steroid injections and were 2- to 3-fold higher on day 21 in II than on day 7 (I or II), but concentrations of prolactin and total glucocorticoids in plasma did not differ during this time. The quantity of prolactin released in response to injection of thyrotropin releasing hormone was greater 10 days after steroid injections than before or during steroid injections. Preinjection concentrations of prolactin were correlated with magnitude of postinjection response to thyrotropin releasing hormone, but response was not correlated with concentrations of steroids in plasma on day of injection.

Effects of heat stress during pregnancy on maternal hormone concentrations, calf birth weight and postpartum milk yield of Holstein cows.

For an evaluation of the effects of heat stress during pregnancy on calf birth weight and postpartum maternal milk yield, 21 cows and 10 heifers were assigned to shade (S; n = 16) or no shade (NS; n = 15) treatments during the last trimester of pregnancy in June 1978. At parturition, all cows were removed from treatment and uniformly managed in the milking herd. At 4-d intervals from d 199 of pregnancy to parturition, respiration rates, rectal temperature, heart rate and Black Globe temperature were recorded and blood samples obtained via tail venipuncture between 1300 and 1600 h. Weekly prepartum body weights of dam, birth weight of calf and subsequent daily milk yield were recorded. Black Globe temperature, rectal temperature and respiration rates were higher in cows given NS. Calf birth weight was lower in the NS group. Milk yield was correlated in a linear manner with calf birth weight, and cows in group NS exhibited reduced lactation performance after calving. Plasma progestin concentrations were higher in heat-stressed cows (6.0 vs 5.1 ng/ml). Estrone-sulfate concentrations were reduced in plasma of NS cows (2,505 vs 4,433 pg/ml). Thus, hormone concentrations of maternal and fetal origin were altered by environment. Plasma thyroxine concentrations were lower in NS cows (51.2 vs 66.4 ng/ml), while plasma triiodothyronine concentrations were elevated (1.8 vs 1.5 ng/ml), indicating altered thyroid hormone metabolism in heat-stressed cows. Heat stress altered endocrine dynamics during pregnancy and reduced calf birth weight and may have indirectly altered subsequent milk yield.

Fetal death in utero: effect on estrone, estradiol-17 beta and progesterone levels in the ewe.

Polyvinyl catheters were placed in the maternal femoral artery (MA) and maternal uterine vein (UV) of 11 near-term ewes and in the umbilical vein of their fetuses. 1-5 days postoperatively 100 ml of air were injected into the umbilical vein of 7 fetuses. 4 fetuses served as controls. Samples of blood from MA were taken 15 min prior to air embolism and every 15 min for 3 h, then at +4, +5 and +6 h after air injection. Plasma levels of estrone (E1) estradiol (E2) and progesterone (P) were determined by radioimmunoassay. In MA and UV of treated ewes there was a significant decrease in P, but not in E1 or E2 after fetal death compared to control ewes. Control levels of P in MA were 9.6 ng/ml; values at 1, +2, +4 and +6 h were 8.8, 3.3, 2.3 and 1.2 ng/ml, respectively.

Periparturient endocrine changes of conceptus and maternal units in Jersey cows bred for milk yield.

Control cows, sired by and bred to bulls with assumed zero estimated breeding values, and selected cows, sired by and bred to bulls of high predicted difference for milk yield, were used. Blood samples were collected via jugular venipuncture on alternate days from 35 to 14 days prepartum, from 14 to 28 days postpartum, and daily from 14 days prepartum to 14 days postpartum. We examined blood hematocrit, and concentrations in plasma of protein, estrone, estradiol, estrone sulfate, progestins, glucocorticoids, luteinizing hormone, and prolactin. Total plasma volume was measured on days -21, -7, and +11. Weekly body weights, prepartum and postpartum, were recorded. All data were analyzed by least squares analysis of variance with day and hematocrit as continuous independent variables. Hematocrit was higher for selected cows throughout the sampling period. Prepartum concentrations of progesterone were higher in selected cows, but concentrations of estrone, luteinizing hormone, and prolactin were lower than in control cows. Hormonal and physiological responses indicated that selection for milk yield influenced both the conceptus and maternal units as measured by prepartum endocrine function.

A study of prostaglandin F2 alpha as the luteolysin in swine: V. Comparison of prostaglandin F, progestins, estrone and estradiol in uterine flushings from pregnant and nonpregnant gilts.

Uterine flushings were collected from 38 gilts representing Days 6,8,10,12,14,15,16 and 18 of the estrous cycle and pregnancy. The same group of gilts were represented within each of the respective days of the estrous cycle and pregnancy, i.e., three to six gilts per day per status. Uterine flushings (about 40ml) were assayed for prostaglandin F (PGF), estrone (E1), estradiol (E2), progestins (P) and protein. Nonpregnant gilts had higher (P < .01) concentrations of P in uterine flushings than pregnant gilts, but pregnant gilts had higher (P < .01) E1 and E2 concentrations. Significant day by status interactions were detected for E1 (P < .05), but not for E2 concentrations in uterine flushings. Total recoverable PGF and PGF concentrations in uterine flushings were greater (P < .01) in pregnant than nonpregnant gilts and significant (P < .01) day by status interactions were detected. In nonpregnant gilts, PGF increased between Days 12 and 16, i.e., during the period of corpora lutea (CL) regression. In pregnant gilts, PGF in uterine flushings increased markedly between Days 10 and 18. Total recoverable PGF on Day 18 of the estrous cycle was only 464.5 +/- 37.6 ng as compared to 22,688.1 +/- 1772.4 ng on Day 18 of pregnancy. Total recoverable protein was also higher (P < .01) in pregnant gilts. These data indicate that PGF synthesis and secretion by the uterine endometrium and/or conceptuses is not inhibited during pregnancy and suggest that PGF is sequestered within the uterine lumen of pregnant gilts, as is the total protein component of endometrial secretions referred to as histotroph.