Postpartum Anestrus Research Articles

The reproductive activity of autumn and spring-lambing ewes given bromocriptine during lactation.

Abstract Reproductive activity during the first 60 days post partum was investigated in three North Country Cheviot (NCC) ewes that lambed in the autumn, and five Poll Dorset and five NCC ewes that lambed in the spring. The ewes were treated with bromocriptine (CB 154, Sandoz) from the first to the eighth week of lactation. Bromocriptine effectively reduced plasma and milk prolactin levels, but this treatment did not induce an earlier onset of ovulation or oestrus in lactating ewes in the autumn or in the spring. A clear seasonal variation in the duration of post-partum anoestrus was apparent in these animals.

ホルスタイン種乳牛に対するProgesterone releasing intravaginal deviceの応用

A progesterone releasing intravaginal device with an estradiol benzoate capsule (PRID) wasapplied to Holstein cows.1) In 4 cows in postparturient anestrus PRID was inserted into the vagina for 12days and 25mg of prostaglandin F2α(PGF2α) was injected intramuscularly 24hours before the removal of PRID. All the cows, exceptone, showed standing estrus within 48hours after this removal. The estrous cows were inseminated artificiallyonce58hours after the removal and became conceived, except one.2) In 8 cows showing an abnormal estrous cycle, PRID was inserted for 12days and superovulation treated with PMSG or FSH and PGF2α48hours before the removal of PRID. The mean numbers of ova collected and normal embryos per donor were 4.4 and 2.9, respectively, and 66% of ova collected from the donors with superovulation was judged as normal.3) In 5 donor cows 1 to 4days after collection following the usual superovulation scheme (first) PRID was inserted for 14days. Superovulation was treated again with PMSG or FSH in combination with PGF2αtreatment 2days before the removal of PRID (second). The proportion of normal embryos was 65.5 and 40.0% in the first and second treatment, respectively.In conclusion, the PRID treatment was effective for the recurrence of estrus in postpartum anestrus and for superovulation in cows showing an abnormal estrouscycle.

Pituitary concentrations of gonadotropins and receptors for GnRH in suckled beef cows at various intervals after calving.

Mature beef cows were slaughtered at 5 (n = 6), 10 (n = 6), 20 (n = 6) or 30 (n = 5) d after calving to identify endocrine events that may affect the duration of postpartum anestrus. Additional cows (n = 6) were slaughtered 12 to 14 d after their first postpartum estrus (luteal phase cows). Anterior pituitary concentrations of luteinizing hormone (LH) were low at d 5 (383 +/- 69 micrograms/g), averaged 445 +/- 103 and 682 +/- 207 micrograms/g at d 10 and 20, respectively, and were elevated (P less than .05) by d 30 (1,097 +/- 174 micrograms) to a concentration similar to luteal phase cows (1,208 +/- 148 micrograms/g). Concentrations of follicle-stimulating hormone (FSH) averaged 12.4 +/- 1.1, 9.6 +/- 2, 8.6 +/- 1.8 and 7.4 +/- 3.3 mg/g at d 5, 10, 20 and 30, respectively. Affinity (1.6 +/- .2 X 10(9) M-1) of anterior pituitary receptors for the GnRH (gonadotropin-releasing hormone) analog (DAla6; des-Gly10, [D-Ala6]-LH-RH ethylamide) and weights (2.1 +/- .1 g) of the anterior pituitaries did not differ among groups (P greater than .05). Number of receptors for GnRH averaged 37 +/- 7, 39 +/- 9, 25 +/- 5 and 23 +/- 5 X 10(-14) M/mg protein at d 5, 10, 20 and 30, respectively. Anterior pituitaries from luteal phase cows contained 22 +/- 2 X 10(-14) M/mg protein of receptors for GnRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive disorders in dairy cattle. II. Interrelationships between pre-or post-service infectious and functional disorders

This retrospective study was aimed at investigating the interrelationships between the various post-partum reproductive disorders whose incidence distribution was reported in a previous paper. There were 343 calving cows, and 319 of them were inseminated at least once. Although approximately one-third of the cows suffered from metritis, its influence on subsequent pathology was only minor. No within-animal relationship could be found between post-partum cyclic anestrus and post-AI anestrus. The distribution of repeat breeding cows showed that almost half of them also had post-AI anestrus, and only 17% had no other disorders. Previous metritis accounted for only 10% of these cases. Embryonic mortality was related only to post-partum cyclic anestrus. Finally, it was found that approximately half of the cows suffered from more than one reproductive disorder with many different relations between the disorders within individuals during post partum. In conclusion, optimal efficiency of post-partum reproduction requires careful checking of all possible disorders.

Reproductive disorders in dairy cattle: I. Respective influence of herds, seasons, milk yield and parity

This study was performed in two large dairy units (with 130 and 213 calving cows each) during one year. The objectives were to investigate 1) epidemiological patterns of main post-partum reproductive disorders (metritis, post-partum and post-service anestrus, repeat breeding and embryonic death) and 2) the impact of herd, calving season, milk yield and parity on these patterns. Approximately 20% of the cows in both herds were not affected by any of the disorders. Prevalence of metritis was high (32 to 44%) and appeared influenced by the herds' conditions interacting with calving months and milk yield effects. Cyclic post-partum anestrus incidence was also essentially affected by the herd effect with an added seasonal interaction. Other disorders in both herds were also primarily subjected to the seasonal effect. Individual milk yield and parity only marginally affected the epidemiological patterns. We concluded that even in similar environmental conditions, no general patterns of incidence of reproductive disorders can be drawn and that they are essentially dependent on the characteristics of each herd management.

Corpora lutea of pregnancy and elevated serum progesterone during pregnancy and postpartum anestrus in woodchucks (Marmota monax).

Serum samples (n = 62) were collected from wild-caught woodchucks (n = 45) that were nonpregnant (n = 3), pregnant (n = 25) or postpartum (n = 34) when bled at the time of capture and/or necropsy, or following maintenance and observation for variable periods of time. Progesterone concentrations were determined by radioimmunoassay and related to the actual or estimated time from parturition which occurs at 31 days postcoitum in this species. Mean serum progesterone levels during the initial, middle and last third of pregnancy were 6.5 +/- 1.7, 22.5 +/- 3.7 and 16.8 +/- 3.2 ng/ml, respectively. Postpartum progesterone levels were elevated above basal values (less than or equal to 0.3 ng/ml) in both lactating and nonlactating animals for 2-3 months postpartum and were not consistently basal until more than 90 days postpartum. Mean progesterone levels at less than 30, 30-60, 61-90, and greater than 90 days postpartum were 25.1 +/- 6.2, 60.6 +/- 18.5, 22.8 +/- 8.7 and 0.4 +/- 0.2 ng/ml, respectively, and those at 30-60 days postpartum were greater than those at midpregnancy (P less than 0.05). Mean corpus luteum diameters were also greater (P less than 0.05) postpartum (2.9 +/- 0.3 mm) than during pregnancy (1.5 +/- 0.3 mm). The correlation between placental scars and ipsilateral corpora lutea indicated that the corpora lutea observed postpartum were the corpora lutea of the recent pregnancy. The termination of each uterine horn in a separate external cervical os precluded the occurrence of transcornual migration.(ABSTRACT TRUNCATED AT 250 WORDS)

EFFECT OF PROGESTERONE AND TEMPORARY WEANING ON CYCLIC ACTIVITY AND FERTILITY OF BEEF COWS AT A PROSTAGLANDIN- SYNCHRONIZED ESTRUS

Three experiments were conducted to assess the effect of short-term calf removal (CR) or treatment with progesterone (P4) on onset of cyclic ovarian activity and fertility in beef cows suckled by a single calf. Estrous cycles of all cows were synchronized by two injections of a prostaglandin F (PGF) analogue 11 days apart. The cows were inseminated at 68 and 92 h after the second PGF injection. In exp. 1, calf removal for 48 h after the second injection of PGF did not alter fertility compared to controls. In exp. 2, cows were treated with 100 mg P4 at the time of the first PGF injection. P4 increased the number of cycling animals by 7% and fertility by 13%, but the differences were not significant. In exp. 3, combinations of CR and P4 were used. When these latter data were summarized and pooled with similar groups from previous experiments, P4 increased cyclic ovarian activity by 9% (P < 0.07) and fertility by 14% (P < 0.04). The results indicate that treatment with P4 caused a moderate increase in onset of cyclic ovarian activity and significantly increased fertility. Key words: Beef cows, postpartum anestrus, progesterone

Characterization of hormonal patterns in the beef cow during postpartum anestrus.

Characterization of hormonal patterns in the beef cow during postpartum anestrus.

Distribution of visible follicles on the ovarian surface in ewes.

Two studies were conducted to determine the distribution of follicles on the ovarian surface in ewes. In Exp. 1, the effect of the corpus luteum on the distribution of follicles was investigated on d 9, 12 and 14 postestrus in unilaterally ovulating ewes. Follicles (greater than or equal to 2 mm diameter) were inventoried by size and distance from the center of the corpus luteum or corpus albicans. There were more small follicles (less than or equal to 4 mm diameter) on d 9 than on d 12 and 14, Although the ovary bearing the corpus luteum had a greater number of large follicles, no positive relationship of the corpus luteum to the diameter of the closest follicle or the distance of the largest follicle was found. In Exp. 2, follicles were inventoried on ovaries from ewes during the estrous cycle, postpartum anestrus, seasonal anestrus and the peripuberal period. During the estrous cycle, two apparent waves of follicular growth were noted. In addition, during the luteal phase the luteal ovary consistently had a larger follicle than the nonluteal ovary. When estimates were made of the effects of size of follicle on distance of the follicle from the reference structure and of distance on size of follicle, presence of luteal tissue, and day of estrous cycle were found to influence the variances. In addition the interaction of these characteristics affected the variation of size or distance. Weighting the distribution of ovarian structures for relative ovarian mass allowed an examination of localization of structures to standardized ovarian areas. More follicles and corpora lutea were found in the middle of the ovary than on the ends. Although the numbers of follicles in a standardized area were correlated with ovarian mass, occurrence of corpora lutea in a standardized area was not significantly correlated with ovarian mass. Collectively, these results are indicative of a local effect by the corpus luteum on the diameter of the largest follicle and a systemic effect on the number of follicles. In addition, because specific regions appear to be more favorable for follicular activity and ovulation, a precise local effect of the corpus luteum is difficult to determine.

The relationship in the response of ovaries of superovulated heifers

Pregnant Holstein–Friesian (HF) heifers were transported from central Europe (defined as temperate conditions) to north-eastern Brazil (defined as tropical, semiarid conditions). They were kept in open-sided pens with a hard floor, a roof for shade and sprinkled with water for 10 min every hour if ambient temperature exceeded 30°C. Their diet was balanced to meet nutritional requirements and they were fed twice daily. Control animals were randomly chosen first and second lactation animals located on a farm 25 km away and receiving similar management. Imported animals were superovulated in 1996 (n=63) and 1997 (n=96), compared to 38 and 45 cows in the control herd. The variates recorded were: the interval post-partum to first oestrus; changes in ovarian size and activity; responses to superovulation; and, embryo quality.The average daily milk yields of the imported cows were 20.0 and 23.3 l in 1996 and 1997, respectively compared to 22.1 l throughout the experiment for cows in the control herd.The post-partum anoestrus interval in the imported cows were 112.1±30.5 days in 1996 compared to 55.0±18.0, 48.2±12.0 and 42.6±10.7 days in 1997 for control cows. The size and functionality of the ovaries was lowest for the imported animals in 1996 but did not differ between other group–year combinations. These animals also had a lower superovulatory response in 1996 than control cows in terms of the number of ovulations (6.4±4.3 versus 13.6±5.9, P<0.05) and good quality embryos (1.2±0.9 versus 4.4±2.1, P<0.05). The two groups of cows did not differ in respect of these characters in the second year of the study.The imported cows had lower reproductive efficiency and responses to superovulation in their first year in their new environment. A period of approximately 1.5 years is required for full adaptation.

Modulation of reproductive hormones by suckling and exogenous gonadal hormones in young beef cows post partum.

Plasma concentrations of LH, prolactin, progesterone and oestradiol-17 beta were measured during post-partum anoestrus in 12 young beef cows (6 suckling, 6 not suckling). A progesterone-releasing intravaginal device (PRID) was inserted on Day 60 post partum for 12 days in 3 cows in each group. Two of three suckling cows exhibited oestrus within 2 days after PRID removal (Day 73) whereas none of the untreated cows showed oestrus before Day 93. Five of six non-suckling cows showed oestrus before Day 60. Intensive bleeding periods on Days 45, 58, 70 and 72 provided plasma samples for LH and prolactin measurements. Suckling did not affect the LH baseline or the number of LH spikes but did decrease the mean value of the spikes; all three of these characteristics were increased for prolactin. The number of prolactin spikes and the length of anoestrus in suckling cows were correlated (r = +0.87, P less than 0.05) as were mean basal LH level and length of anoestrus (r = -0.89, P less than 0.05). A decrease in plasma LH occurred in suckling and non-suckling cows during the period (Days 60-72) they were treated with gonadal hormones.

Effect of the sire on the subsequent lactation performance in the dam

ABSTRACTThe effects of 18 buffalo sires, used in 2 years of a progeny-testing programme, on the subsequent lactation performances of their mates, were investigated from a study of 685 lactation records. The traits studied were: milk production, lactation length, length of post partum anoestrus, number of services per conception and length of service period (calving to conception). Parity of calving and sire had a significant effect on 305-day milk yield and lactation length of the mates. Between the 2 years, the sires did not differ for any of the traits of their mates. Although the breeding value of the sires, high or low, did not differ significantly, the sires with high breeding value tended to depress the milk production in the subsequent lactation of their mates and vice versa (r= −0·05). The birth weight of the calves significantly affected milk production. It was concluded that all methods of sire evaluation are likely to be biased by the effect of sires.

Influence of GnRH infusion on endocrine parameters and duration of postpartum anestrus in beef cows

The effect of an intravenous infusion of gonadotrophin releasing hormone (GnRH) on the duration of postpartum anestrus in suckled beef cows was studied. Twenty-eight, mature, suckled beef cows were assigned in equal numbers to one of four treatment groups which were based on infusion with saline or GnRH (15ug/hour for 12 hours) and stage postpartum (pp) (20 or 35 days). Serum LH and progesterone were determined by radioimmunoassay for the period which began 5 days pre-infusion and ended at 55 days postpartum (ie: 35 or 20 days post-infusion). Serum LH remained below 5ng/ml during infusion in all control cows. Peak serum LH values, times of LH peaks, and duration of LH responses (means ± SE) during infusion were 49 ± 12 ng/ml, 162 ± 42 minutes and 7.8 ± 1.3 hours for the 20 day group and 44 ± ng/ml, 144 ± 6 minutes, and 8.2 ± 1.1 hours for the 35 day group respectively. Serum progesterone levels indicated that the proportion of cows showing the onset of estrous cycles within 10 days of infusion was greater in the 20 day pp GnRH group (4/7) than the 20 day pp saline group (0/7) (p < .05) but was not significantly different between the 35 day pp GnRH (4/7) and 35 day pp saline (2/6) groups. The incidence of estrus was not affected by GnRH treatment and was 37% in all cows prior to 55 days pp. It was concluded that infusions of GnRH for 12 hours at a rate of 15 ug/hour could induce estrous cycles in suckled beef cows treated at 20 days postpartum.

Etude de quelques caractéristiques de reproduction chez la brebis Peulh, du Niger

The duration of the oestrous cycle, oestrous, pregnancy and post-partum anoestrus, as well as the kinetics of plasma progesterone and prolactin levels during each of those periods, were studied in ewes of a tropical breed without wool. The value of the parameters and the profiles of the two hormones were comparable to those of other European and tropical breeds, suggesting that the Sahelian climate has little to do with the sexual endocrinology of the sheep.

Influence of suckling by Friesian cows on milk production and anoestrus

The effect of time (morning or afternoon), intensity (three or four calves per cow), frequency Once or twice daily) and duration (1, 2, 4 or 8 weeks) of suckling on the performance of multiparous Friesian cows in early lactation was studied in four experiments. In each experiment there was a group of cows that were machine milked twice daily from calving. Milk production from sucked cows was greater during the suckling period than from machine-milked cows in the same period, but in no case was there any significant difference between suckling treatments. Increases in production during the 8-week suckling period ranged from 7.1 (P &gt; 0.05) to 19.4% (P&lt; 0.05), or from 75-21 8 kg. The extra milk produced by the cows sucked once daily went to the calves, and similar (P &gt; 0.05) quantities or significantly less milk (P&lt; 0.05) was produced at the alternate machine milkings compared with non-sucked cows in the same period. Regardless of suckling treatment in early lactation, the cows failed to show any carryover benefit. Lactation length and liveweight change in cows was unaffected by suckling treatment. The interval of post-partum anoestrus increased by about 6 days for each additional week of suckling. The average increase due to 8 weeks suckling in the four experiments ranged from 41-66 days. Teat damage increased with duration of twice-daily suckling, but had no effect on yields after sucking stopped. Teat damage of cows sucked once or twice daily to 8 weeks was similar. The incidence of mastitis was low in both sucked and machine-milked cows, and was not related to suckling treatment. Multiple sucking of Friesian cows in early lactation is a means of obtaining more milk from individual cows without incurring penalties in liveweight and body condition loss; it has no effect on post-weaning milk production.

Effect of progestagen intravaginal sponges and PMSG on synchronisation of oestrus in maiden heifers and on interval from calving to oestrus in beef cows

Abstract The effectiveness of progestagen sponges plus PMSG in inducing and synchronising oestrus and pregnancy in nulliparous heifers was assessed. Eighty-one percent of the treated heifers were synchronised, but none of the controls. The hormone treatment advanced the mean calving date by 19 days, but there was no difference between treated and control in the percentage of heifers that finally calved. The interval between calving and first oestrus for hill-country beef cows 2–10 years old in an untreated control group was 94 days, in a group treated with progestagen-impregnated sponges for 21 days was 98 days, and in a group treated with these sponges plus 1000 i.u. of PMSG at the time of withdrawal was 85 days. The last treatment reduced post-partum anoestrus by 11 days in comparison with the mean of the other two treatments (P < 0.01). There was no difference between age groups in the percentage of cows showing oestrus, conceiving to first service, and calving for the control treatment. However, in the two hormone treatments none of the 2-year-old cows conceived to first oestrus and 13% calved, but 46% of cows in the older age groups conceived to first oestrus and 79% calved.

Effects of early weaning on reproductive efficiency in beef cows

Six hundred eighty-three mature cows of the Devon, A. Angus, and Hereford breeds were used to investigate the effect of weaning 90 days after calving on the postpartum reproduction (anestrus and pregnancy rate). The calving pariod was 90 days, from September to November (Spring 1976). The breeding period, also of 90 days, began at the end of the calving period and was from December to February (Summer 1977). The calves were separated from their mothers with a mean age of 90 days for the “W” group of cows and 200 days for the “S”. Early weaning increased overall conception in the 90 days breeding period by 43.07% (P < .001) and reduced the postpartum anestrus from 60.42% in the “S” group to 13.79% (difference of 46.63% − P < .001) in the “W” group.

Hormonal control of oestrous cycle in the ewe (a review)

During the cycle, the secretion of progesterone by the corpus luteum inhibits the positive feedback of oestrogens and thus prevents the LH discharge, and also primes the central nervous system for oestrous behaviour. Prostaglandin F 2α has been identified as the hormone produced by the uterus which causes luteal regression. The LH discharge leading to ovulation follows the demise of the CL. None of the characteristics of the LH surge (duration, maximum level, total release) can be related to ovulation rate. However, the interval from onset of oestrus to the beginning of the LH discharge is greater in highly prolific breeds than in less prolific ones. The knowledge of these physiological processes leading to oestrus and ovulation makes possible the control of ovarian activity in the ewe. In cyclic females, the control of the timing of the LH discharge and ovulation can be obtained either by inducing luteolysis with PGF 2α or its synthetic analogues after day 4–5 of the cycle, or by artificially lengthening the luteal phase with exogenous progesterone or progestagens. During the seasonal and post-partum anoestrus, PGF 2α is ineffective and progesterone or progestagens alone are generally unable to induce oestrus and ovulation. Addition at the end of progestagen treatment of inducers of follicular growth and LH release is necessary. Both PMSG and synthetic GnRH are used for this purpose.

Effect of duration and pattern of underfeeding in early lactation on milk production and reproduction of dairy cows

Eighty cows of mixed breeds were fed so that they calved in moderate condition, and were then strip-grazed at different rates over the first ten weeks of lactation. Two levels of feeding were used factorially ; either ad libitum pasture intake (H) or an allowance of pasture which resulted in an intake of 7 kg of pasture dry matter cow-1 day-1 (L), for the first or second five-week period. After ten weeks, all cows were grazed as one group as well as seasonal conditions permitted. The effects of five-week periods of underfeeding on milk, milk fat and protein yield were equal and additive over the first ten weeks of lactation, HL and LH groups producing 11 kg and LL group 22 kg less milk fat than the HH group. Residual effects, however, from week 11 to the end of lactation differed markedly between treatments, the LH group producing the same as, but HL and LL groups producing 9 and 21 kg less than, the HH group. Residual effects of only 0.7 and 1.0 times the immediate effect were recorded for underfeeding in the first five and ten weeks of lactation, respectively. Cows underfed in early lactation gained more liveweight in later lactation at the expense of milk yield. An extra 10 kg pasture dry matter was required in early lactation to give an extra kilogram of milk fat over the lactation. The calving to conception interval in the LL group was 18 days longer than in the HH group (P &lt; 0.05). The delay was associated with both a longer post-partum anoestrus and a higher number of services per conception. There was no effect of stage of underfeeding (HL vs LH) on reproductive performance. The poor understanding of factors affecting residual effects from underfeeding in early lactation is highlighted. As pattern of underfeeding has little effect on lactation performance, this gives the farmer considerable flexibility in allocating feed supplies in early lactation.

Oestrus synchronisation with a prostaglandin analogue: I. Systems in lactating dairy cattle

Summary Three trials were completed to compare different regimes for the use of an analogue of prostaglandin F2 alpha(“Estrumate”: ICI) in the breeding management of herds of lactating dairy cows with seasonally concentrated calving patterns. The first regime involved two injections of ‘Estrumate’ 11 days apart, followed by insemination, either at 72h and 96h after the second injection, or at the first observed oestrus. Every cow had calved at least 40 days before the first injection. The second regime involved a single ‘Estrumate’ injection given to every cow not inseminated during the first seven days of the breeding programme. Treated cows were inseminated when observed in oestrus within 48h of injection, or at 72h and again at 96h. The third regime utilised the technique of tail-painting during the pre-mating period to identify groups of cycling cows which were subsequently givena single injection of “Estrumate” and inseminated 72h lateror at a subsequent behavioural oestrus. All regimes significantly altered the conception pattern from that obtained in untreated herd-mates. The variable incidence of post-partum anoestrus, genuine short oestrous cycles and the degree of precision in oestrus synchronisation in lactating dairy cows resulted in many animals being unnecessarily injected and/or inseminated. The third regime overcame most of these problems and could have application in many largeherds. The identification of cycling animals and insemination at detected oestrus are important components of programmes using prostaglandins for the purpose of oestrus synchronisation in lactating cows in seasonal dairy herds.