Early Postpartum Beef Cows Research Articles

Transvaginal follicular aspiration and embryo development in superstimulated early postpartum beef cows and subsequent fertility after artificial insemination

This study was conducted to investigate in early postpartum suckled beef cows with and without FSH pre-stimulation: (i) the influence of the postpartum period on the number and quality of oocytes recovered by ovum pick-up (OPU), (ii) the overall efficiency of the OPU/IVP embryos from days 30 to 80 postpartum and (iii) if repeated OPU negatively affect fertility following a fixed-time artificial insemination protocol. After parturition suckled Angus cows ( n = 30) were divided in three groups ( n = 10 group −1). All cows were anestrous at the commencement of experimental treatments (30.0 ± 3.2 days postpartum, mean ± SD; range 25–34 days). Group 1 treatments included: dominant follicle ablation (DFA), FSH treatment and OPU procedure 5 days after DFA. A total of 9 mg FSH (Ovagen™) was administered s.c. once a day over 2 days at equal doses (4.5 + 4.5 mg). For fertility test the cows received an intravaginal progesterone treatment from Days 78 to 86 postpartum and were fixed-time artificially inseminated (FTAI) at 56 and 72 h after device removal. Group 2: as cited for Group 1 with no FSH treatment. In both groups, OPU was repeated four times (Days 35, 49, 63 and 77 postpartum) and the collected oocytes classified as viable were in vitro matured, fertilized and presumptive embryos cultured for 8 days. Group 3 (Control FTAI): cows that had not previously aspirations were FTAI as Groups 1 and 2. Pregnancy was diagnosed by means ultrasonography 39 days after FTAI. The numbers (mean ± SEM) of follicles visible and aspirated at the time of OPU in FSH-treated cows were greater ( P < 0.05) than in non-treated cows (10.6 ± 0.6 and 8.4 ± 0.4 vs. 8.0 ± 0.5 and 4.6 ± 0.3, respectively). Following FSH treatment, the number (mean ± SEM) of recovered oocytes per cow per OPU session and percentage of viable oocytes were greater in the treated ( P < 0.05) than in non-treated animals (3.0 ± 0.1 and 39.5% vs. 1.5 ± 0.1 and 30.0%). The cleavage and embryo development rates were similar ( P > 0.05) for both groups (14.8 and 6.4% vs. 16.6 and 5.5%). After FTAI the pregnancy rates were not different ( P > 0.05) among groups (70, 60 and 90% for Groups 1, 2 and 3, respectively). We can conclude that (1) FSH-treated suckled postpartum cows can be a source of oocytes for in vitro fertilization and (2) repeated DFA/OPU applied during postpartum period did not affect the subsequent fertility following FTAI.

Effect of treatment with two intravaginal inserts on the uterine and vaginal microflora of early postpartum beef cows

To describe the bacterial species found within the uterus and vagina of early postpartum (10 to 20 d) beef cows treated for 14 d with (i) two intravaginal (CIDR-B) progesterone releasing inserts (C-P4; n=31); (ii) two identical but blank inserts (C-BL; n=15); (iii) untreated controls (CON; n=15). It was hypothesised that due to the locally immunosuppressive effects of progesterone on the uterus, the bacterial microflora of C-P4 would be altered by this treatment in contrast to CON and C-BL. Cows were enrolled at two intervals 7 d apart. Blood samples were collected at 0, 7 and 14 d after beginning treatments for subsequent progesterone assay. A triple guarded swabbing technique was used to collect bacteriological samples from the uterus of every cow on days 0, 7 and 14 following CIDR insertion. Swabs were also collected from the inserts and vagina of every cow on day 14. Due to the small sample sizes, only descriptive statistics were generated. Plasma progesterone levels were maintained at mid-luteal phase concentrations by the intravaginal progesterone releasing inserts (C-P4: 4.2 +/- 0.4 ng/mL at 7 d; 3.6 +/- 0.2 ng/mL at 14 d), although increased progesterone concentrations were found in 4/15 CON and 9/15 C-BL cows on day 14. Bacteria were isolated from 32/61 (52%) of all uterine samples collected at the time of insertion. Uterine and vaginal swabs from CON cows showed a marked reduction in isolates over time such that 14 d after insertion only 1/15 uterine swabs grew bacteria. In contrast, C-BL and C-P4 treated cows failed to show reductions in the number of uterine or vaginal isolates at 14 d after device insertion. Heavy growths of Pseudomonas aeruginosa and Actinomyces pyogenes were found on the intravaginal inserts from C-BL and C-P4 cows. Cows enrolled in the second week of the study that received intravaginal inserts (C-P4 + C-BL) were more likely to have Pseudomonas isolated from the uterus than those enrolled in week 1 (1/18 versus 14/28). The presence of two intravaginal inserts, regardless of hormone content, substantially altered the profile of uterine and vaginal bacteria in early postpartum beef cows. It was suspected that because of the early stage at insert application, the cervix had not involuted sufficiently to provide an adequate microbial barrier to the uterus. Pseudomonas aeruginosa was the predominant species isolated from both uterine and insert cultures after 14 d of treatment but may have been a contaminant, due to the greater proportion of cows infected with it that had been enrolled in the second week of the study.

Relations between Plasma IGF-I Concentrations during Treatment with CIDR-based or Ovsynch Protocol for Timed AI and Conception in Early Postpartum Japanese Black Beef Cows

We examined the relations between plasma insulin-like growth factor (IGF) -I concentrations during treatment with CIDR-based or Ovsynch protocol for timed AI and conception and plasma steroid concentrations in early postpartum Japanese Black beef cows. Cows in the control group (Ovsynch; n = 21) underwent Ovsynch protocol (GnRH analogue on Day 0, PGF(2alpha) analogue on Day 7, and GnRH analogue on Day 9), with AI on Day 10, approximately 20 h after the second GnRH treatment. Cows in the Ovsynch+CIDR group (n = 22) received Ovsynch protocol plus a CIDR for 7 days (starting on Day 0). Cows in the further treatment group (EB+CIDR+GnRH; n = 22) received 2 mg of estradiol benzoate (EB) on Day 0 in lieu of the first GnRH treatment, followed by the same treatment as in the Ovsynch+CIDR protocol. Plasma IGF-I concentrations were determined on Days -7, 0, 7, 9 and 17. Conception rates were improved in the CIDR-combined groups (both CIDR-treated groups were combined) relative to Ovsynch group (P < 0.05) for cows with low IGF-I concentrations (<1,000 ng/ml) on Days -7, 0, and 7, but improved conception rate produced by the CIDR-based protocols did not occur in cows with a high IGF-I concentration (> or =1,000 ng/ml). Plasma estradiol-17beta concentrations increased from Day 0 to 7 (P < 0.05) and were unchanged from Day 7 to 9 in the Ovsynch group with low IGF-I concentrations on Day 0, while they were unchanged from Day 0 to 7 and increased from Day 7 to 9 (P < 0.05) in the Ovsynch group with high IGF-I concentrations on Day 0 and in the CIDR-combined group. Plasma progesterone concentrations in the Ovsynch group with low IGF-I concentrations on Day 0 were higher on Day 14 than in the Ovsynch group with high IGF-I concentrations on Day 0 and in the CIDR-combined group (P < 0.05). In conclusion, CIDR-based protocols may improve conception relative to Ovsynch in early postpartum beef cows with lower plasma IGF-I concentrations at the start of the protocols. This improvement is probably due to prevention of premature increases of estradiol-17beta and progesterone concentrations, which occurred in cows with low IGF-I concentrations treated with Ovsynch, by the CIDR treatment.

The effect of eCG or estradiol at or after norgestomet removal on follicular dynamics, estrus and ovulation in early post-partum beef cows nursing calves

In post-partum anestrous beef cows suckling calves, neither the choice of hormonal regime to ensure the presence of a healthy dominant follicle at the end of a progestagen treatment nor the optimum hormone to induce estrus and ovulation is clear. Twenty-eight beef cows, in good body condition, 25–30 days post-partum, were assigned to one of four treatments: (i) 3 mg norgestomet (N) implant with 5 mg estradiol valerate (EDV) and 3 mg N injection at the time of insertion (Crestar) for 5 days followed by 600 IU eCG at the time of implant removal; (ii) Crestar for 5 days as in (i) followed by 0.75 mg estradiol benzoate (EDB) 24 h later; (iii) Crestar for 9 days followed by 600 IU eCG at the time of implant removal; and (iv) Crestar for 9 days followed by 0.75 mg EDB 24 h later. Ovarian scanning was preformed from 4 days before implant insertion until ovulation and 4 days postovulation to detect the CL. Daily blood samples were collected from day 20 post-partum until second ovulation for FSH and E 2 assay. Data were analyzed using analysis of variance. There was no effect of the stage of follicle wave at the time of implant insertion on interval to new follicle wave emergence (range 1–7 days; mean 4.7 days). FSH concentrations were decreased to 5.9±2.0 and 7.7±1.1 ng/ml for pre- and post-selection cows 1 day after start of treatment; thereafter, they increased on Day 2 to 7.9±2.0 and 11.0±1.1 ng/ml and on Day 3 to 10.3±2.7 and 11.4±1.7 ng/ml for pre- and post-selection cows, respectively, despite high-estradiol concentrations at that time. There was no effect of treatment on the interval from implant removal to ovulation (3.2–4.0 days) or on the number of cows detected in estrus (26 of 27 cows). The size of the ovulatory follicle in cows given 0.75 mg EDB 24 h post implant removal was decreased in animals at the pre-selection stage (12.2±0.1 mm) of the follicle wave compared with those at the post-selection stage (15.3±0.9 mm) at implant removal. Cows given 600 IU eCG at the pre-selection phase of follicular growth had multiple ovulations (4.0±1.1). Cows given EDV at the start of a 5-day implant period had higher estradiol concentrations before and on the day of implant removal than those given EDV at the start of a 9-day implant period. The injection of 0.75 mg EDB 1 day after implant removal tended to increase concentrations of estradiol one day later. In conclusion, 5 mg EDV and 3 mg N at insertion of a 3 mg N implant resulted in variable new follicle wave emergence 1–7 days later in post-partum beef cows nursing calves (22 of 27); both eCG and EDB were equally effective at inducing estrus after implant removal in cows in good BCS, but eCG resulted in a significant increase in ovulation rate in cows treated before dominant follicle selection.

Transvaginal ultrasound-guided oocyte aspiration for production of embryos &amp;lt;i&amp;gt;in vitro&amp;lt;/i&amp;gt;

Abstract. reproductive potential in genetically valuable animals (BEAL et al., 1992). Now that repeatable oocyte retrieval methods are being fine-tuned, it is likely these procedures will become routinely used to obtain oocytes for further gamete and embryo research and also by seedstock producers for in vitro embryo production from farm animals in the commercial sector. The use of transvaginal ultrasound-guided oocyte aspiration and IVF procedure does offer an alternative to cattle producers who have genetically valuable cows that for some reason are unable to produce viable embryos through standard embryo collection procedures. This technology can be used on oocytes harvested from older ovulating or nonovulating cows, females with physical injuries (e.g., fractured leg) and problem cows having an abnormal cervix. Good success has been reported using IVF procedures on oocytes obtained from supplemental follicles of cows with cystic ovarian disease. With IVF the potential exists for more embryos to be produced in a shorter period of time, since the procedure can be repeated on the same cow 3 to 4 times or more a month. At this station, we are harvesting oocytes from early postpartum (&lt; 40 days) beef and dairy cattle, before the female begins cyclic activity. The approach allows the opportunity to produce one or more extra calves from the cow before she is mated for a natural pregnancy. Currently, transvaginal ultrasound-guided oocyte aspiration is now being used to harvest valuable oocytes from minor farm animal breeds, from domestic females representing rare bloodlines, clinically infertile females and reproductively senescent cows. Research continues to find applications for this technology, including harvesting oocytes from young prepubertal heifers and early postpartum beef cows for in vitro embryo production. The use of ultrasound-guided oocyte aspiration should not be overlooked to obtain oocytes for in vitro embryo production and to aid in germplasm preservation of endangered exotic species.

Advancement of ovulation and oestrus after temporary calf removal and FSH supplementation in postpartum beef cows

To evaluate the effect of temporary calf removal and/or FSH supplementation on post-partum ovarian and oestrous activity, 40 anoestrous multiparous Aberdeen Angus cows under grazing conditions were used. The animals were allocated, on the basis of calving date and body condition, to four initially similar groups according to a 2 × 2 factorial design (ten animals per group) involving a 72 h calf removal (TCR) and exogenous follicle stimulating hormone supplementation (FSH). Anoestrus was determined by measuring plasma progesterone concentrations before treatments, which began at 29.6 ± 4.9 days postpartum. Total FSH supplementation (12 mg, porcine FSH) was performed by six intramuscular decreasing doses (3, 3, 2, 2, 1 and 1 mg, respectively) distributed at 12 h intervals, beginning 24 h before TCR. Oestrus detection (twice daily) and blood sample collection (every 2–3 days) were performed from 7 days before the start of treatments and for 45 days thereafter. The TCR plus FSH group had higher oestrous and ovulation rates at 40 days postpartum (control, 10% and 10%; TCR, 10% and 10%; FSH, 10% and 10%; TCR plus FSH, 60% and 60%) and 60 days postpartum (control, 30% and 30%; TCR, 50% and 50%; FSH, 40% and 50%; TCR plus FSH, 80% and 100%). These differences were significant ( P < 0.05) for oestrous rates at 40 days postpartum and for ovulation rates at 40 and 60 days postpartum. TCR plus FSH significantly shortened ( P < 0.05) the intervals (mean ± s.e.m., days) from calving to first ovulation (control, 61.2 ± 5.5; TCR, 62.8 ± 4.6; FSH, 61.6 ± 3.8 and TCR plus FSH, 43.4 ± 3.1) and a similar trend ( P > 0.05) was observed for the intervals from calving to first oestrus (control, 61.2 ± 5.5; TCR, 62.3 ± 5.4; FSH, 63.4 ± 3.9 and TCR + FSH, 47.7 ± 5.2). The rate of short first luteal phases (⩽ 10 days) was: control, 40%; TCR, 33%; FSH, 43%; TCR plus FSH, 89% ( P < 0.12). In summary, TCR plus FSH resulted in increased ovulation and oestrus rates, shorter postpartum intervals, but subnormal corpora lutea were formed following the first ovulation in early postpartum beef cows.

Pregnancy rates for embryos transferred from early postpartum beef cows into recipients with normal estrous cycles.

Survival rate of embryos from first ovulations of postpartum cows with SHORT (6.9 +/- 0.3 days; n = 35) or NORMAL (17.1 +/- 0.3 days; n = 42) luteal phases and quality of the embryos on Day 6 were compared. At 19 to 23 days postpartum, cows were allotted to receive a norgestomet implant for 9 days (normal luteal phase) or to serve as untreated controls (short luteal phase). Calves were weaned 7 days after initiation of treatment to induce behavioral estrus in cows for mating. In 25 cows, growth of the ovulatory follicle was monitored by ultrasonography. On Day 6 after estrus, embryos were recovered nonsurgically, and live embryos were transferred into recipient cows exhibiting normal estrous cycles. The medium used to flush the embryos from the uterus of each donor cow was assayed for prostaglandin F2 alpha (PGF2 alpha). Days from calf removal to estrus and size of ovulatory follicles at ovulation (4.1 +/- 0.3 days and 16.7 +/- 0.7 mm, respectively) did not differ between NORMAL and SHORT cows. Interval from detection of the ovulatory follicle to ovulation was longer in NORMAL (10 +/- 0.7 days) than in SHORT cows (8 +/- 0.6 days; p < 0.05). Rates of recovery of an embryo or ovum (64%), rates of fertilization (65%), and quality or stage of development of Day 6 embryos did not differ between SHORT and NORMAL cows. Overall pregnancy rate from recovered oocytes was 13% for SHORT and 32% for NORMAL cows (p = 0.06); survival of fertilized oocytes was 23% for SHORT and 47% for NORMAL cows (p = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced postpartum anestrus of suckled beef cows treated with microencapsulated luteinizing hormone-releasing hormone analog.

This study evaluated the effect of microencapsulated LHRH agonist (D-Trp6-LHRH) on gonadotropin release and occurrence of estrus in early postpartum beef cows. Angus cows (n = 54) were assigned randomly to two treatment groups at d 5 postpartum. Group 1 received a single i.m. injection of D-Trp6-LHRH (LHRH-A) encapsulated in poly-DL-lactide-coglycolide, calculated to release 15 micrograms of LHRH-A per day for 30 d (n = 23). Group 2 received vehicle only (control, n = 31). Blood samples (15-min intervals for 6 h) were obtained on d 5, 10, 20, 30, and 40 postpartum for evaluation of LH and FSH concentrations (n = 12 per group). Days to first postpartum estrus were reduced by treatment with LHRH-A (Group 1, 43.7 +/- 4.2 d vs Group 2, 55.9 +/- 4.7 d; P < .05). However, days to conception were similar between groups (68.9 +/- 7.9 vs 76.7 +/- 6.7 d, respectively). On the day of treatment, cows treated with LHRH-A had higher mean concentrations of LH and FSH than did controls (8.3 +/- 1.4 vs 2.0 +/- .4 ng/mL for LH and 211.0 +/- 8.6 vs 51.2 +/- 2.7 ng/mL for FSH (P < .05). There were no differences in mean concentrations of LH or FSH between treatment groups on d 10, 20, 30, and 40 postpartum. Cows given LHRH-A had more (P < .05) LH pulses on d 10 and 30 postpartum than did controls. This study demonstrated that microencapsulated D-Trp6-LHRH reduced the postpartum anestrous interval in suckled beef cows.

Role of prostaglandin F 2α in follicular development and subsequent luteal life span in early postpartum beef cows

In postpartum cows expected to have corpora lutea (CL) of normal (norgestomet-treated) compared to short (control) life spans, function of the largest follicle increases after an increase in concentrations of prostaglandin F 2α (PGF). To determine whether PGF alters follicular growth and subsequent life span of the CL, 43 crossbred beef cows (19 to 22 d postpartum) were assigned to one of four treatments: 1) control (C; n = 10), 2) control + PGF (CPGF; n = 10), 3) norgestomet (N; n = 13), 4) norgestomet + flunixin meglumine (NFM; n = 10). Flunixin meglumine inhibits prostaglandin endoperoxide synthase. On day 0, N and NFM cows received a 6 mg implant of norgestomet. From days 3 through 8, CPGF and NFM cows were injected every 8 hr with 10 mg PGF im or 1 g FM iv, respectively. Implants were removed on day 9. On day 11, each cow received 1000 IU of hCG im to induce formation of CL. Follicular growth was monitored by daily ultrasonography from days 6 through 11. In a majority of the cases ( 25 32 ), the largest follicle present on day 6 was still the largest on day 11; frequency of persistence did not differ with treatment. Rate of growth of the largest follicle was greater in CPGF than in N cows (.6 ± .1 vs .3 ± .1 mm/d, respectively; P < .05) but did not differ between C and NFM cows (.4 ± .1 and .5 ± .1 mm/d, respectively). Concentrations of estradiol in NFM cows were higher (P < .05) on day 3 and declined to concentrations similar to those of the other treatments on day 9. There were no differences among treatments in concentrations of estradiol after implant removal. Proportions of cows forming CL in response to hCG were 8 10 , 8 10 , 8 13 and 6 9 in groups C, CPGF, N, and NFM, respectively and did not differ with treatment. Proportions of cows with normal CL were greater (P < .05) in N than in CPGF ( 4 8 vs 0 8 ) and in NFM than in C ( 5 6 vs 2 8 ). In conclusion, changes in PGF during follicular growth did not play a significant role in the formation of CL of normal life span in postpartum beef cows.

Embryo recovery from early postpartum beef cows

Embryo recovery from early postpartum beef cows

Influence of Infusion of Prostaglandin F (PGF ) and Weaning on Surface and Histologic Populations of Ovarian Follicles in Early Postpartum Beef Cows

Twenty-four beef cows were infused continuously for 11 d (d 2 to 13 after parturition) into the descending aorta with either prostaglandin F2 alpha-Tham salt (PGF2 alpha; 33.5 mg/d; n = 12) or with .9% NaCl (saline; n = 12) vehicle. Cows from each infusion treatment then were assigned to three slaughter groups (G). Cows in G1 and G2 were suckled until slaughter on d 15 and 35, respectively, whereas calves in G3 were weaned on d 31 and cows were slaughtered on d 35 after parturition. Nonatretic and atretic (greater than 4 pycnosis) antral follicles (greater than .15 mm) on ovaries ipsilateral to the previously gravid uterine horn were evaluated by histological techniques. Compared with saline infusion, PGF2 alpha increased mean diameters of the largest (F1) follicles on the ipsilateral (d 15 and 35; P less than .07) and contralateral (d 15; P less than .07) ovaries (surface evaluation) as well as mean diameters of the largest (F1, d 35; P less than .002), second- and third-largest (F2, F3 d 15 and 35; P less than .01) nonatretic follicles (histologic evaluation) in suckled cows. Compared with suckled cows slaughtered on d 35, weaning on d 31 increased the number of medium follicles (3 to 5 mm), diameters of the three largest nonatretic follicles, percentage of large nonatretic follicles (greater than 3.67 mm) and mitotic index of class 3 (.68 to 1.57 mm) follicles in saline-infused cows. In contrast, in PGF2 alpha-infused cows, weaning decreased (P less than .05 to P less than .001) all of these responses. Surface and histologic evaluations of follicular activity indicated that postpartum infusion of PGF2 alpha stimulated development of large follicles. In response to weaning, PGF2 alpha infusion favored development of those large follicles toward ovulation or atresia on nonovulated follicles.

Coincident secretion of follicle-stimulating hormone and luteinizing hormone in early postpartum beef cows: effects of suckling and low-level increases of systemic progesterone.

The current experiment was conducted with beef cows during the first 2 weeks postpartum (PP) to determine the effects of suckling and low-level increases of systemic progesterone on secretory characteristics of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in peripheral plasma. Variables measured included mean gonadotropin concentrations, FSH/LH pulse frequencies, pulse amplitudes and synchrony of coincident release. Suckled (S) cows had lower (P less than 0.01-P less than 0.05) mean concentrations of FSH and LH in plasma, lower (P less than .05) FSH and LH pulse frequencies and a lower (P less than 0.05) pulse synchrony (21.6 vs 72.3% coincident pulses) than nonsuckled (NS) cows on Day 7 PP. Neither FSH nor LH pulse amplitude was affected by suckling. Similar differences existed for mean gonadotropin concentrations, pulse frequencies and pulse synchrony on Day 14 PP between S and NS cows. Implanting cows with progesterone implants on Day 7 PP, which chronically increased plasma progesterone to 0.5-0.6 ng/ml, increased (P less than 0.05) mean plasma FSH and LH concentrations, FSH and LH pulse frequencies and pulse synchrony (87.5 vs. 66.3%) in NS-implanted (NSI) versus NS-nonimplanted (NSNI) cows. Progesterone implants had no beneficial effect in S cows. Thus, three major findings seem pertinent: 1) associated with the suckling-induced depression of episodic gonadotropin release was a marked decline in FSH/LH pulse synchrony; 2) a high degree of FSH/LH pulse synchrony (72-88%) was restored in the absence of suckling when gonadotropin pulse frequency increased to 4-5/6 h; 3) the absence of suckling, followed by the provision of low-level progesterone stimulation for 7 days, appeared to have additive effects on FSH and LH secretion. These results provide evidence that the neuroendocrine block associated with suckling in early PP beef cows is, in addition to being associated with depressed LH release, comprised of characteristic anomalies in FSH secretion, FSH/LH pulse synchrony and failure to respond to a putative hypothalamo-hypophyseal potentiator, progesterone.