Progesterone concentrations in beef heifers bred at puberty or third estrus

Peripheral serum progesterone concentrations were evaluated in beef heifers following breeding collected on d 6 +/- 1, 9 +/- 1 collected on d 6 +/- 1, 9 +/- 1 and 12 +/- 1 (estrus = d 0) after the puberal estrus of all heifers and after the third estrus of E3 heifers. Progesterone concentrations were higher (P less than .05) for heifers in E1 compared with heifers in E3 on d 6, 9 and 12 after breeding to a fertile bull. Progesterone concentrations on d 6, 9 and 12 did not differ (P greater than .10) between pregnant heifers in E1 and E3; however, non-pregnant heifers in E1 had higher (P less than .05) concentrations of progesterone compared with non-pregnant heifers in E3 on each day. Concentrations of progesterone did not differ (P greater than .10) between non-pregnant heifers in E1 and heifers of E3 during their puberal cycle. Pregnant heifers in E1 and E3 had higher (P less than .05) concentrations of progesterone on each day than non-pregnant heifers in their respective treatments. There were no interactions (P greater than .10) between treatment, pregnancy status and day-of-estrous cycle for concentrations of progesterone. Results of this study indicated that luteal function differed between heifers that failed to conceive at their puberal estrus and heifers that failed to conceive at third estrus. However, concentrations of progesterone did not differ between heifers that conceived at puberal or third estrus. The relationship of changes in luteal function from the puberal through the third estrous cycle and pregnancy is not clear.     

Progesterone concentration in defatted milk of dairy cows in early pregnancy.

Progesterone concentrations have been measured in defatted milk of British Friesian cows of four herds during the oestrus cycles (other than short cycles) immediately before artificial insemination (AI) at oestrus and immediately after AI (in non-pregnant cows), and during early pregnancy. Differences in mean progesterone concentrations between herds were significant (P less than 0.05) on all days within the day 10-18 period after AI, both in pregnant and in non-pregnant, inseminated cows but were not significant between pregnant and non-pregnant cows within herds until day 17 or 18. It is concluded that up to this time (that of luteolysis in non-pregnant cows) undefined factors, variable among herds, can have a much greater influence on the rate of progesterone secretion by corpora lutea and consequent progesterone concentration in plasma and milk than does the presence of conceptuses. Maximum mean progesterone concentration reached during early pregnancy in two herds did not differ significantly; it was reached in the 11-15-day period in one herd but not until 46-50 days in the second. Mean progesterone concentration declined after day 90.     

Re-insertion of a progesterone-containing intravaginal device to synchronise returns to oestrus in dairy heifers

Recommendations for oestrus synchronisation of dairy heifers using progesterone-containing intravaginal devices suggest re-insertion of used devices 16 days after first insemination for a period of 5 days to allow a second opportunity for artificial insemination. Controlled studies on the effectiveness of re-using intravaginal devices to synchronise returns to oestrus in non-pregnant dairy heifers are lacking. A clinical trial was conducted involving 750 Friesian heifers in 13 herds. After an initial synchronisation programme, the used intravaginal devices were re-inserted 14 or 16 days after first insemination into half of the heifers in each herd for a period of 5 days. After the first synchronisation programme, 47.5% of heifers remained non-pregnant. Re-insertion of used intravaginal devices for 5 days significantly increased the number of non-pregnant heifers detected in oestrus and inseminated by 48 hours after device removal compared to heifers in which devices were not re-inserted (45.2% v. 27.3%, p < 0.05, in herds where intravaginal devices were re-inserted on day 14; 48.8% v. 13.6%, p < 0.05, in herds where intravaginal devices were re-inserted on day 16). Re-insertion at 14 or 16 days after first insemination was equally effective in increasing visible returns to service. However, the number of non-pregnant heifers synchronised for a second round of artificial insemination was less than expected. Conception rate to the re-synchronised oestrus was unaffected by the treatment. It is concluded that the additional procedures of CIDR re-insertion, removal, tailpainting and insemination involved in there-synchrony programme, and the relatively low in-calf rate to the re-synchronised round of insemination, reduced the potential benefits of re-synchronisation.     

The use of progesterone administered intravaginally and pregnant mare serum gonadotrophin given by injection in controlled breeding programs in beef and dairy cattle

Five experiments involving 1,244 cows and heifers were carried out to investigate the factors which might influence the calving performance to fixed-time artificial insemination following intravaginal administration of progesterone (PRID) and intramuscular injection of pregnant mare serum gonadotrophin (PMSG). Factors examined were duration of PRID treatment, time of treatment after calving, time and dose PMSG and lactational status. Experiments 1, 2 and 3 were carried out on milked Friesian cows, experiment 4 on Friesian heifers and experiment 5 on suckled and dry Herefords. All cows were inseminated once with frozen/thawed semen 54 to 58 h or 46 to 50 h after completion of PRID treatment. Overall there was a progressive increase in calving rates with an increase in the duration of treatment from 12 to 14 to 16 days but there was little or no effect of time after calving (4 v 7 weeks) at which treatment was commenced. The poorer calving performance of cows treated for 12 to 14 days was associated with relatively high peripheral levels of plasma progesterone at the time of the PRID removal, suggesting the presence at the end of treatment of residual secretory luteal tissue. There was an effect on calving performance of PMSG given at the time of PRID removal but its effect varied according to the duration of PRID treatment. After 12 days treatments (experiments 1 and 5) PMSG had little effect, whereas after 14 days treatments, 0, 500 and 750 IU PMSG gave calving rates of 27%, 40% and 46% in experiment 2 and 5%, 24% and 38% in experiment 5.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the effects of gonadotropin-releasing hormone, human chorionic gonadotropin or progesterone on pregnancy per artificial insemination in repeat-breeder dairy cows

Three different treatments were compared to improve pregnancy per artificial insemination (P/AI) in repeat-breeder (RB) dairy cows. All cows (n = 103) were assigned to one of four groups: (1) gonadotropin-releasing hormone (GnRH); (2) human chorionic gonadotropin (hCG); (3) once-used controlled internal drug release (CIDR) device; and (4) control. All treatments performed 5-6 days after artificial insemination (AI) and milk samples were collected just before treatment for progesterone assays. There were no significant differences in milk fat progesterone concentration among trial groups. Cows were observed for estrus signs thrice daily. Pregnancy per AI on day 45 in hCG and CIDR groups were significantly higher than GnRH and control groups (60.0% and 56.0% vs. 26.9% and 29.6%, respectively), but there were no differences in P/AI between GnRH and control groups. There were also no significant differences between hCG and CIDR groups. Milk fat progesterone concentrations were compared between pregnant and non-pregnant cows in each group and only in the hCG group it was significantly lower in pregnant cows. In conclusion, treating repeat-breeder cows with hCG or once-used CIDR 5-6 days after AI improved P/AI.     

Infertility in heifers caused by pathogenic strain of Mycoplasma bovigenitalium

Mycoplasma bovigenitalium (M. bovigenitalium, strain AL) was inoculated by insemination during estrous into the uterus or the cervix of 12 heifers. The inoculum consisted of a mixture of M. bovigenitalium (strain AL) and diluted semen taken from a highly fertile bull free of mycoplasma infection. Mycoplasma organisms were recovered 3 days postinoculation (PI) from the vaginal mucous of eight of 12 inoculated heifers, and at weekly intervals thereafter until the time of necropsy. All inoculated heifers had granular vulvovaginitis; some also had mucopurulent vaginal discharges. Six of the 12 infected heifers were inseminated more than once, yet none became pregnant. Macroscopic changes observed at necropsy in the genital tracts, in addition to granular vulvovaginitis, consisted of mucopurulent discharges emananting from the uterus, cervix, and vagina. All ovaries had corpora lutea. Mycoplasmas were recovered at necropsy from eight of the 12 heifers. Isolations were made from the vaginal wall, cervix, uterus, right and left oviducts, and the ovaries. All recovered mycoplasms were identified as M. bovigenitalium. It was concluded that M. bovigenitalium (strain AL) can cause inflammatory changes and infertility in heifers.     

Clinical and endocrinological investigation of possible ovulatory failure in a dairy cow

Ovulatory failure was diagnosed in a cow by repeated rectal palpation. The follicle continued to increase in size accompanied by a thickening of the wall and retention of fluid in the central cavity. Plasma hormone profiles showed normal preovulatory oestradiol and luteinising hormone peaks. Four days later progesterone concentrations rose and were maintained for 14 days before falling to baseline concentrations as in a normal luteal phase. Twenty-two days after the luteinising hormone peak, the animal returned to oestrus.     

A comparison of two techniques for the synchronisation of oestrus in dairy heifers.

Seventy-four heifers in four separate breeding groups were allocated into two treatment groups for oestrus synchronisation. Group 1 was given a combination of an initial injection of norgestomet and oestradiol valerate together with a norgestomet ear implant left in place for nine days. Group 2 was given two injections of the synthetic prostaglandin luprostiol 10 days apart. The animals in group 1 were artificially inseminated once 48 hours after the removal of the implant and those in group 2 were inseminated once 72 hours after the second injection of luprostiol. Subsequently any returns were rebred by either AI or natural service. There was no significant difference between the numbers of animals in the two treatment groups which were diagnosed pregnant 33 to 35 days after insemination, although the implant treatment gave a higher overall proportion of pregnancies (70 per cent, 51 per cent). It also gave significantly smaller numbers of 'open' days over the whole of the breeding period. A study of individual animals by progesterone assay and investigation of ovarian structures by real-time ultrasound showed that some of them had unusual progesterone profiles but nevertheless became pregnant. It would appear that a corpus luteum may be responsive to prostaglandins even though it is secreting only a low level of progesterone.     

Plasma Progesterone during the Luteal Phase and Pregnancy in Parturient and Barren Blue Fox Vixens

Abstract

The variation in progesterone secretion during the luteal phase and pregnancy in blue fox vixens was analyzed. Progesterone was measured in blood plasma once or twice a week using radioimmunoassay. The material was allocated into three groups; five mated, but barren, blue fox vixens, six mated vixens with implantation zonès in the uterus, but no cubs at parturition, and 26 normally parturient vixens. The progesterone profiles for the three different groups of females showed a steady increase in progesterone immediately after mating. Maximum values were observed on days 8–12 of pregnancy. Then the progesterone levels decreased gradually until delivery around day 52. The levels of progesterone were found to be significantly different (P<0.05) between non-pregnant and pregnant females from day 22 after mating. The plasma progesterone level seems to be affected by the presence of conceptuses.     

Studies on canine pregnancy using B-mode ultrasound: Diagnosis of early pregnancy and the number of conceptuses

The ultrasonic (B-mode) detection of canine pregnancies was first achieved 21 to 23 days after the calculated luteinising hormone peak when daily examinations were made in six bitches. In 51 pregnant bitches examined for the first time between 20 and 35 days, one bitch was incorrectly diagnosed as non-pregnant 24 days after the calculated luteinising hormone peak. In only 31-8 per cent of pregnancies was conceptal number accurately determined. The greatest tendency was to underestimate the number of conceptuses.     

Conception Rates after AI in Swedish Red and White Dairy Heifers: Relationship with Progesterone Concentrations at AI

Blood samples were collected from 211 dairy heifers at the time of field insemination [artificial insemination (AI)]. Heifers were defined as either first‐service heifers (n = 91) or third to eigth‐service heifers [presumed (third AI, n = 60)] or well‐defined repeat breeders (greater than the fourth AI, n = 60). Plasma progesterone concentrations at AI were evaluated in relation to oestrous behaviour at AI and conception rates post‐AI. Conception rates after third AI were good, but conception rates decreased markedly after fourth AI and onwards. Those heifers that did not become pregnant after AI had significantly higher basal progesterone concentrations (>0.5 nmol/l) at AI, so‐called suprabasal concentrations, compared with those which conceived after AI (irrespective of the number of AI practised). Relative risk for repeat breeding was 58% after AI performed at suprabasal progesterone concentrations, while it was 42% at basal (0.5) progesterone concentrations. Results from this field study confirm results obtained in earlier controlled studies of repeat‐breeder heifers (RBH), indicating that the current definition of repeat breeding should be retained. Analysis of suprabasal progesterone concentrations could be considered as a tool for identification of RBH, provided that heat detection and AI timing are optimal. Besides considering the direct costs involved in repeat breeding, it remains to be determined whether it would be economically beneficial to identify and exclude RBH from the breeding population.     

Hormone secretion and characteristics of estrous cycles after treatment of heifers with human chorionic gonadotropin or prostaglandin F2 alpha during corpus luteum formation

Fertility in cattle is related positively to concentrations of progesterone in blood during the estrous cycle preceding insemination. This study determined whether treatment of heifers with prostaglandin F2 alpha (PGF2 alpha) or human chorionic gonadotropin (hCG) during d 2 to 4 of an estrous cycle affected progesterone during that cycle and whether hormone secretion during the cycle and onset of subsequent estrus were related to progesterone secretion. Nine Holstein heifers were assigned to an experiment designed as a triplicate Latin square, and each heifer received each of three treatments during three consecutive estrous cycles. Treatments were: saline (control, 1 ml) on d 2, 3 and 4 after estrus; hCG, 1000 IU on d 2, 3 and 4; and PGF2 alpha, 25 mg on d 3 with repeated doses 12 and 24 h later. Progesterone throughout the estrous cycle was higher in heifers given hCG than in those given saline. Progesterone during the first week of the cycle was lower in heifers given PGF2 alpha than those given saline, but means for these two groups were similar thereafter. Number of peaks of 15-keto,13,14-dihydro-PGF2 alpha (PGFM) during 24 h after onset of luteolysis was lower in heifers given hCG than in those given saline or PGF2 alpha. Patterns of secretion of luteinizing hormone and estradiol at subsequent estrus were not affected by treatment. Temporal relationships among hormone secretion and onset of estrus were unaffected by treatment.     

Serum IGFBP4 concentration decreased in dairy heifers towards day 18 of pregnancy

This study was conducted to determine if the main components of the somatotropic axis change during the early phase of pregnancy in the maternal blood system and whether differences exist on day 18 after pregnancy recognition by the maternal organism. Blood samples of pregnant heifers (Holstein Friesian; n = 10 after embryo transfer) were obtained on the day of ovulation (day 0), as well as on days 7, 14, 16 and 18 and during pregnant, non-pregnant and negative control cycles. The oncentrations of progesterone (P₄), oestrogen, growth hormone (GH), insulin-like growth factor-1 and -2 (IGF1, -2) and IGF-binding protein-2, -3 and -4 (IGFBP2, -3, -4) were measured. The mRNA expressions of growth hormone receptor 1A, IGF1, IGF2, IGFBP2, IGFBP3 and IGFBP4 were detected using RT-qPCR in liver biopsy specimens (day 18). In all groups, total serum IGF1 decreased from day 0 to 16. Notably, IGFBP4 maternal blood concentrations were lower during pregnancy than during non-pregnant cycles and synchronized control cycles. It can be speculated that the lower IGFBP4 in maternal blood may result in an increase of free IGF1 for local action. Further studies regarding IGFBP4 concentration and healthy early pregnancy are warranted.     

Evaluation of factors that affect embryonic loss in dairy cattle

OBJECTIVE: To identify potential risk factors for embryonic loss before 35 to 42 days of gestation in dairy cattle. DESIGN: Prospective observational study. ANIMALS: 381 cows. PROCEDURE: Body condition score was determined at the time of artificial insemination (AI; day 0) and on days 20, 23, and 27 and between days 35 and 41; serum progesterone concentration was measured on days 0; 20 or 21; and 23, 24, or 25. Cows were excluded from analyses if day 0 serum progesterone concentration was > or = 1.0 ng/mL and classified as pregnant on day 23 if serum progesterone was > 1.5 ng/mL on day 20 or 21 and day 23, 24, or 25. Cows were examined via transrectal ultrasonography on day 27 or 28 and rectally palpated for pregnancy on days 35 to 41. RESULTS: 39% of cows that were pregnant on day 23 lost their embryo by day 27, and 18% of cows that were pregnant on day 27 or 28 were not pregnant on days 35 to 41. Breeding a pregnant cow posed the greatest risk for embryonic loss at both time periods. Mean serum progesterone concentrations on day 21 or 22 and day 23, 24, or 25 were lowest for cows that lost an embryo between days 24 and 28. Cows with a linear somatic cell count score > 4.5 before AI were twice as likely to lose the embryo by 35 to 41 days, compared with cows with a score < 4.5. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that embryonic loss could be reduced by more accurate estrus detection, reducing mastitis, and strategies to improve progesterone concentration after breeding.     

Suppression of preovulatory luteinizing hormone surges in heifers after intrauterine infusions of Escherichia coli endotoxin

A study was conducted to test the hypothesis that high cortisol concentrations associated with products of infections (endotoxin) cause derangement in the neuroendocrine mechanism controlling ovulation in heifers. Eight Holstein heifers were given 2 injections of prostaglandin (PG), 11 days apart, to synchronize estrus. Starting from 25 hours after the second injection of PG (PG-2), the uterus of each heifer was infused with 5 ml of pyrogen-free water (control, n = 3) or Escherichia coli endotoxin (5 micrograms/kg of body weight) in 5 ml of pyrogen-free water (treated, n = 5), once every 6 hours for 10 treatments. Blood samples were obtained every 15 minutes via indwelling jugular catheter for an hour before and 2 hours after each infusion, then hourly until an hour before the next infusion. Ultrasonography of the ovaries was performed every 12 hours, starting 24 hours after PG-2 injection until 96 hours after PG-2 injection. Serum concentrations of luteinizing hormone and cortisol were determined by validated radioimmunoassays. Changes in cortisol concentrations were not detected in control heifers with preovulatory luteinizing hormone surges at 60 to 66 hours after PG-2 injection, followed by ovulations 72 to 96 hours after PG-2 was injected. None of the treated heifers ovulated, and the resulting follicular cysts (14 to 18 mm diameter) persisted for 7 to 21 days. In all treated heifers, serum cortisol concentrations increased (4- to 10-fold) during the first 2 hours after each infusion and then decreased gradually until the next infusion. Luteinizing hormone concentrations remained at baseline values throughout the treatment period in all treated heifers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of progesterone and human chorionic gonadotrophin administration five days postinsemination on plasma and milk concentrations of progesterone and pregnancy rates of normal and repeat breeder dairy cows.

Treatment with a progesterone-releasing intravaginal device between days 5 and 12 after estrus elevated (p less than 0.05) plasma progesterone concentrations between days 6 and 8 in comparison with controls. Treatment with injectable progesterone (200 mg) on days 5, 7, 9 and 11 postestrus did not increase plasma progesterone concentrations over controls. The administration of 1500 IU human chorionic gonadotrophin (hCG) on day 5 after estrus resulted in a sustained increase (p less than 0.01) in plasma progesterone concentrations from day 8 until day 20 when measurements ceased. Pregnancy rates, as a result of artificial insemination (AI) at the pretreatment estrus, in these treatments (n = 12-14 each), were unaffected by any of the treatments and ranged from 57.1 to 75.0% at 45-60 days post-AI. In a field trial, of 36 repeat breeder cows treated with 1500 IU hCG 5.5 days after insemination, 47.2% were pregnant at 60 days, whereas 39.5% of saline-treated controls were diagnosed pregnant. Treatment with hCG significantly (p less than 0.05) increased milk progesterone concentrations over controls on days 14 and 20 after insemination.     

Effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given GnRH

The effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given 100 microg of GnRH im were determined in three experiments. In Experiment 1, heifers were given GnRH 3, 6 or 9 days after ovulation; 8/9, 5/9 and 2/9 ovulated (P<0.02). Mean plasma concentrations of progesterone were lowest (P<0.01) and of LH were highest (P<0.03) in heifers treated 3 days after ovulation. In Experiment 2, heifers received no treatment (Control) or one or two previously used CIDR inserts (Low-P4 and High-P4 groups, respectively) on Day 4 (estrus=Day 0). On Day 5, the Low-P4 group received prostaglandin F(2alpha) (PGF) twice, 12 h apart and on Day 6, all heifers received GnRH. Compared to heifers in the Control and Low-P4 groups, heifers in the High-P4 group had higher (P<0.01) plasma progesterone concentrations on Day 6 (3.0+/-0.3, 3.0+/-0.3 and 5.7+/-0.4 ng/ml, respectively; mean+/-S.E.M.) and a lower (P<0.01) incidence of GnRH-induced ovulation (10/10, 9/10 and 3/10). In Experiment 3, 4-6 days after ovulation, 20 beef heifers and 20 suckled beef cows were given a once-used CIDR, the two largest follicles were ablated, and the cattle were allocated to receive either PGF (repeated 12h later) or no additional treatment (Low-P4 and High-P4, respectively). All cattle received GnRH 6-8 days after follicular ablation. There was no difference between heifers and cows for ovulatory response (77.7 and 78.9%, P<0.9) or the GnRH-induced LH surge (P<0.3). However, the Low-P4 group had a higher (P<0.01) ovulatory response (94.7% versus 61.1%) and a greater LH surge of longer duration (P<0.001). In conclusion, although high plasma progesterone concentrations reduced both GnRH-induced increases in plasma LH concentrations and ovulatory responses in beef cattle, the hypothesis that heifers were more sensitive than cows to the suppressive effects of progesterone was not supported.     

Megestrolacetat applied for oestrusinduction and oestrussynchronization in heifers (author's transl)]

Forty-seven heifers with the diagnosis anoestrus were treated with 15 mg to 60 mg megestrolacetat (Niagestin "NOVO") per os for 10 days. Thirty heifers showed oestrus within 10 days after treatment and 56% of these conceived after first insemination. There was no significant difference in fertility after different doses of megestrolacetat. Ten cycling heifers were synchronized with 50 mg megestrolacetat per os for 14 days. On the first day of treatment 5 mg oestradiolvalerat was given intramuscularily. All heifers came into heat and were inseminated 2--4 days after treatment. Fifty per cent were pregnant 55 days after insemination. Dosage of megestrolacetat for cows and heifers are discussed.     

Bovine cystic ovarian disease: plasma hormone concentrations and treatment.

Ovarian function in 91 dairy cows with cystic ovarian disease was assessed by rectal palpation and by plasma hormone analysis before and after treatment. Plasma analysis showed that 84% of the cysts were correctly classified clinically and only these cows are considered further. Luteinised cysts occurred in 59 cows whereas only 18 had non-luteinised cysts. The mean plasma concentrations of luteinising hormone (LH), follicular stimulating hormone (FSH), progesterone, oestradiol and testosterone were not significantly different when compared with values at relevant stages of the oestrous cycle in normal cows. Success of treatment with progesterone, a synthetic prostaglandin, human gonadotrophin (HCG), or gonadotrophin releasing hormone (GnRH) was not dependent upon prior hormone concentrations, except for the prostaglandin which required active luteal tissue. LH and FSH concentrations in cows with luteinised cysts were not significantly different before and after successful treatment with GnRH or progesterone. Normal luteal function was not always established after treatment of non-luteinised cysts with GnRH.     

Effect of time of oocyte collection and site of insemination on oocyte transfer in mares

The objective of the study was to compare embryo development rates after transfer of oocytes collected 22 or 33 h after hCG injection into recipients inseminated within the uterus or the oviduct. Oocytes were collected at approximately 22 or 33 h after hCG injections and incubated for approximately 16 or 1.5 h, respectively, before transfer. Intrauterine inseminations using 1 x 10(9) progressively motile sperm were done approximately 12 h before and 2 h after transfer. For intraoviductal inseminations (gamete intrafallopian transfer [GIFT]), semen was centrifuged through a Percoll gradient, and 200,000 progressively motile sperm were transferred with oocytes into the oviduct. Time of oocyte collection (22 or 33 h) after hCG injection did not affect embryo development rates (17/25, 68%, vs 12/23, 52%, respectively; P = 0.40). When results from oocyte collections at 22 and 33 h after hCG were combined, oocyte transfer with intraoviductal vs intrauterine insemination resulted in similar (P = 0.70) embryo development rates (12/22, 55%, and 17/26, 65%, respectively). However, the interaction between time of oocyte collection and site of insemination tended to be significant (P = 0.09), suggesting that GIFT using oocytes collected at 33 h after hCG may not be as effective as using oocytes collected at 22 h after hCG. Because intraoviductal insemination requires a low number of sperm, GIFT could be used in cases of male subfertility, frozen semen, or sexed sperm.