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1.
The influence of exposure to exogenous estradiol on the interval from parturition to first ovulation, luteinizing hormone (LH) secretion and luteal function was examined in cows. Cows were assigned at parturition to one of three treatments. Cows received either a 3.0 (1-E; n = 30) or .75 cm (1/4-E; n = 28) implant containing 17 beta-estradiol or served as untreated control animals (C; n = 33). Implants were administered within 2 days following parturition and removed on day 40 postpartum (day 0 = day of parturition). Single blood samples were collected twice weekly and analyzed for progesterone to determine length of postpartum anestrus and duration of the initial increase in progesterone. Sequential blood samples were collected on day 35 +/- .1 postpartum (15 min intervals for 18 hrs) from 5 cows in each treatment and analyzed for LH. Concentrations of estradiol were higher (P less than .01) in the 1-E (5.3 +/- .24) than in C (3.9 +/- .23) or 1/4 E (3.9 +/- .25) cows on day 35 postpartum. The interval from parturition to the first estrous cycle of normal duration was similar for cows in the C and 1-E treatment (53 +/- 2.4 and 56 +/- 2.4 days, respectively). Cows in the 1/4-E treatment had a longer (P less than .05) interval (68 +/- 2.5 days). Secretion of LH was similar among treatments on day 35 postpartum. The first normal luteal phase after parturition was preceded by a transient rise in progesterone in 81, 64 and 85% of the cows in the C, 1-E and 1/4-E treatments, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

2.
Body condition score is used as a management tool to predict competency of reproduction in beef cows. Therefore, a retrospective study was performed to evaluate association of BCS at calving with subsequent pregnancy rate, days to first postpartum ovulation, nutrient status (assessed by blood metabolites), and calf BW change in 2- and 3-yr-old cows (n = 351) managed and selected to fit their environment of grazing native range over 6 yr at the Corona Range and Livestock Research Center, Corona, NM. Cows were managed similarly before calving, without manipulation of management, to achieve predetermined BCS at parturition. Palpable BCS (scale of 1 to 9) were determined by 2 experienced technicians before calving. Cows were classified to 1 of 3 BCS groups prior calving: BCS 4 (mean BCS = 4.3 ± 0.02), 5 (mean BCS = 5.0 ± 0.03), or 6 (mean BCS = 5.8 ± 0.06). Cows were weighed weekly after calving and serum was collected once weekly (1 yr) or twice weekly (5 yr) for progesterone analysis to estimate first postpartum ovulation beginning 35 d postpartum. Year effects also were evaluated, with years identified as either above or below average precipitation. Days to first postpartum ovulation did not differ among calving BCS groups (P = 0.93). Pregnancy rates were not influenced by calving BCS (P = 0.83; 92%, 91%, 90% for BCS 4, 5, and 6, respectively). Days to BW nadir was not influenced by BCS at calving (P = 0.95). Cow BW was different at all measuring points (P < 0.01) with BCS 6 cows having the heaviest BW and cows with BCS 4 the lightest. Cows with calving BCS 4 and 5 lost more (P = 0.06) BW from the initiation of the study to the end of breeding than cows with BCS 6. However, cow BW change at all other measurement periods was not different (P ≥ 0.49) among calving BCS groups. Serum glucose and NEFA concentrations were not influenced by calving BCS (P ≥ 0.51). Calf BW at birth (P = 0.60), branding (55-d BW; P = 0.76), and weaning (205-d BW; P = 0.60) were not impacted by cow calving BCS. Body condition score did not influence overall pregnancy rates, indicating that young cows can have a reduced BCS and still be reproductively punctual. Therefore, these results indicate that reproductive performance of young cows with reduced BCS may not be affected when managed in extensive range conditions.  相似文献   

3.
The objective of this study was to determine whether an antiestrogen (enclomiphene) would shorten the interval to first estrus and conception in postpartum beef cows. Sixty postpartum Angus beef cows were stratified by age, body condition, and calving date and were randomly assigned to one of two treatment groups. Group 1 cows (n = 24) received three silastic implants, each containing 150 mg of enclomiphene, on d 20 postpartum. Implants were removed on d 30 postpartum. Group 2 cows (n = 28), received empty implants and served as controls. Cows were artificially inseminated at first detected estrus. Estrus detection and ovulation were further verified by increased serum progesterone. Concentrations and pulse frequencies of LH were determined from blood samples collected at 15-min intervals for 6 h on d 20, 25, 30, and 40 postpartum. Hypothalami and pituitaries were collected from four cows in each treatment group on d 30 postpartum and analyzed for concentrations of estradiol receptors. Concentrations of total and unoccupied hypothalamic and pituitary estradiol receptors were reduced by enclomiphene. Neither concentrations nor pulse frequencies of LH differed significantly between treatment groups on any of the 4 d. Days to first estrus did not differ (P greater than .05) between enclomiphene-treated (57 +/- 6; n = 24) and control (56 +/- 4; n = 28) cows. Days to conception did not differ between treated (81 +/- 9) and control (79 +/- 8) cows. The dose of enclomiphene used in this study reduced hypothalamic and pituitary estrogen receptors but did not alter secretion of LH or days to first estrus in the postpartum beef cow.  相似文献   

4.
An experiment was performed to evaluate the effect of the side of ovulation with respect to the previously gravid uterine horn on fertility of cows inseminated at one of two periods postpartum. All cows were treated with an intravaginal progesterone insert for 7 d and received estradiol benzoate (2 mg, i.m.) at the time of device insertion, prostaglandin F2alpha (25 mg, i.m.) at the time of device removal, and estradiol benzoate (1 mg, i.m.) 30 h after device removal. All cows were inseminated 28 to 30 h after the second treatment with estradiol benzoate, regardless of observed estrus. Cows treated in Period 1 received inserts at 16 to 20 d postpartum and were inseminated at 25 to 29 d postpartum. Cows treated in Period 2 received inserts at 26 to 30 d postpartum and were inseminated at 35 to 39 d postpartum. Diameter of the largest follicle at insert removal was greater in cows treated in Period 2 (10.1 +/- 0.3; mm +/- SEM) than in cows treated in Period 1 (9.1 +/- 0.3; P < .05). Diameter did not differ with the side of ovulation in respect to the previously gravid uterine horn. Diameter was greater in cows 5 to 9 (10.3 +/- 0.3) than in cows 3 to 4 (9.0 +/- 0.3) or 10 to 13 (9.4 +/- 0.6) yr of age (P < .01). The proportion of cows that ovulated from the ovary contralateral to the previously gravid uterine horn was greater (P < .05) than of those that ovulated from the ipsilateral ovary, and the incidence of ovulation was reduced in cows 3 to 4 yr of age (P < .01). Conception rate tended to be greater for ovulation from the ipsilateral compared with the contralateral ovary, relative to the previously gravid uterine horn (P < .10) and for ovulation from the right than the left ovary (P < .06). Conception rate was less if cows ovulated a follicle that was < 9 mm than a follicle > or = 9 mm in diameter at insert removal (P < .01) and was greater in cows inseminated in June than in April or May (P < .05). In conclusion, in cows in which estrus was synchronized at 25 to 39 d postpartum, ovulation from either the ovary ipsilateral to the previously gravid uterine horn, or the right ovary, tended to increase fertility.  相似文献   

5.
Our objectives were to determine the effects of early ovulation on fertility and uterine health of dairy cows. Four hundred and forty‐five Holstein cows (185 primiparous and 260 multiparous) from five herds were used. Blood samples were collected at 21, 35 and 49 days in milk (DIM) and cows were considered to be cyclic at 21 DIM (Cyc21) if serum progesterone (P4) concentration was above 1 ng/ml, cyclic by 49 DIM (Cyc49) if P4 concentration was above 1 ng/ml at 35 or 49 DIM, or not cyclic (NotCyc) if P4 concentration was below 1 ng/ml at all sample times. Endometrial cytology for diagnosis of subclinical endometritis was examined at 49 DIM in a subset of 414 cows. Cows in the group Cyc21 had increased hazard of insemination, for the first service, compared with cows in Cyc49 [hazard ratio (HR) = 1.40; 95% CI = 1.10–1.79; p = 0.006] and NotCyc (HR = 2.07; 95% CI = 1.52–2.82; p < 0.001). Cows in the Cyc49 group also had increased hazard of insemination compared with cows in the NotCyc group (HR = 1.47; 95% CI = 1.13–1.93; p = 0.005). Median days to insemination were, respectively, 71, 76 and 96 for cows in Cyc21, Cyc49 and NotCyc groups. Cows in Cyc21 had greater first service pregnancy per AI than Cyc49 [38.6 vs 28.1%; adjusted odds ratio (AOR) = 1.67; 95% CI = 1.01–2.75; p = 0.04] and NotCyc (38.6 vs 23.6%; AOR = 2.08; 95% CI = 1.08–4.00; p = 0.03). Pregnancy per AI was similar in Cyc49 and NotCyc cows (28.1 vs 23.6%; AOR = 1.25; 95% CI = 0.70–2.24; p = 0.45). Cows in Cyc21 had increased hazard of pregnancy up to 300 DIM compared with Cyc49 (HR = 1.52; 95% CI = 1.17–1.96; p = 0.002) and NotCyc (HR = 1.98; 95% CI = 1.41–2.78; p < 0.001). Cows in Cyc49 tended to have increased hazard of pregnancy compared with NotCyc (HR = 1.31; 95% CI = 0.96–1.77; p = 0.09). Median days to pregnancy were, respectively, 103, 147 and 173 for cows in Cyc21, Cyc49 and NotCyc groups. Cows in the Cyc21 group had decreased prevalence of subclinical endometritis compared with cows in the NotCyc group (29.9 vs 43.7%; AOR = 0.53; 95% CI = 0.29–0.97; p = 0.04); however, the prevalence did not differ from the Cyc49 group (29.9 vs 39.1%; AOR = 0.68; 95% CI = 0.41–1.14; p = 0.15). Cyc49 cows had similar prevalence of subclinical endometritis compared with NotCyc cows (AOR = 0.77; 95% CI = 0.46–1.29; p = 0.32). Early postpartum ovulation was associated with improved uterine health and fertility.  相似文献   

6.
Thirty-six postpartum Holstein cows consisting of eighteen cows that shed the placenta soon after calving (NRP) and eighteen cows that retained placenta greater than 24 h (RP) were used. There were four treatment groups. Group I consisted of 9 NRP cows which received intramuscular injection of sterile saline on day 15 postpartum. The second group consisted of 9 NRPN cows which received 100 micrograms of gonadotrophin releasing hormone on day 15 postpartum (NRPT). The third group consisted of 9 RP cows which received saline on day 15 postpartum (RPN) and the fourth group consisted of 9 RP cows which received 100 micrograms of gonadotrophin releasing hormone on day 15 postpartum (RPT). Blood samples were collected once daily during the first month and once every other day during the second month postpartum. In addition fourteen cows (RPT, n = 7; NRPT, n = 7), were used to study short-term changes in serum luteinizing hormone concentrations following gonadotrophin releasing hormone treatment on day 15 postpartum. Blood samples were obtained from these cows every 15 min during 1 h before and 6 h after gonadotrophin releasing hormone administration. Sera from all samples were assayed for progesterone and luteinizing hormone concentrations. Starting from four days after calving rectal palpations and ultrasound examinations of the ovaries were carried out once every four days until day 28 postpartum in order to monitor ovarian changes. All cows were inseminated on the first estrus after day 60 postpartum and examined for pregnancy between 35 and 42 days after insemination.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
Effects of heat stress during the last third of gestation on reproductive changes postpartum were studied in Holstein cows. Cows and heifers 160 to 190 d of gestation were assigned in June 1978 to shade (n = seven cows and two heifers) or no shade (n = eight cows and two heifers) management treatments. After parturition, all cows (n = 19) were moved to the milking herd and managed uniformly. On the day of calving and on each Monday, Wednesday and Friday thereafter until d 50 postpartum, jugular blood samples were collected. Beginning approximately 7 d postpartum, the reproductive tract of each cow was examined rectally after collection of blood samples. Estrus was monitored twice daily and cows were inseminated after d 45 postpartum. Prepartum heat stress increased 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) concentrations postpartum and increased the rate of uterine involution. Regardless of prepartum treatment, progesterone concentrations indicated that luteal phases had begun by d 12.4 +/- 1.3 postpartum, which was about 3 d before PGFM was basal. The first luteal phase lasted only 10.7 +/- .9 d. First estrus was not detected until d 32.3 +/- 4.8 postpartum. The previously gravid uterine horn had a negative effect on ovarian volume, diameter of the largest follicle and percentage of ovaries with a corpus luteum. However, prepartum heat stress attenuated this effect. This study indicates that heat stress prepartum had residual effects on postpartum reproductive changes, and that the previously gravid uterine horn exerted some control, which was attenuated by heat stress, over ovarian recrudescense. Even though heat stress prepartum affected sensitive measures of postpartum reproductive function, it did not alter days to first estrus, days open (102.3 +/- 13.1) or services/conception (2.5 +/- .3).  相似文献   

8.
The effect of gonadotropin-releasing hormone analogue (GnRH-A) or follicular aspiration at the onset of progesterone-based timed artificial insemination (TAI) on subsequent follicular growth and synchronization of ovulation was examined in early postpartum Japanese Black cows. A total of 40 (22 in Exp. 1 and 18 in Exp. 2) Japanese Black cows at 20-30 days postpartum were fitted with a progesterone releasing internal device (PRID) for 7 days, injected with a prostaglandin F2α analogue upon removal of the PRID and GnRH-A 48 h later, and inseminated 18 h after GnRH-A injection. In Exp. 1, the animals were divided into three groups (untreated control, GnRH-A injection or follicular aspiration) of different treatments on the first day of PRID insertion (day 0), and the synchronized ovulation rate in the follicular aspiration group (100%; 8/8) tended to be higher (P = 0.077) than that in the control group (42.9%; 3/7). In Exp. 2, follicular growth in the GnRH (n = 9) and follicular aspiration (n = 9) groups was monitored by ultrasonography. Four out of the nine animals in the GnRH group had a corpus luteum on either day 4 or day 7 (OV group), and the other five animals had no induced ovulation (NOV group). The diameter of the ovulatory follicle on day 9 in the OV group (1.44 ± 0.11 cm) tended to be greater (P = 0.078) than that in the NOV group (1.13 ± 0.07 cm). Follicular aspiration at the onset of PRID-based TAI of early postpartum Japanese Black cows, regardless of the resumption of ovarian cyclicity, tended to result in a higher rate of synchronization of ovulation than that of the untreated controls.  相似文献   

9.
AIMS: To quantify the effect of treating lactating dairy cows that had histories of periparturient disorders or disease with a single intrauterine infusion of 0.5 g cephapirin, 3-6 weeks prior to the start of the seasonal breeding period. METHODS: Cows (n=690) from spring-calving dairy herds (n=22) were enrolled in a prospective case-control study if they had a history of dystocia, a dead calf at calving or within 24 h of calving, retained foetal membranes (RFM), metabolic disease, twins or a vulval discharge 13 days postpartum. Cows were blocked by age, periparturient condition and calving date, and randomly assigned to be either treated with 0.5 g of cephapirin by intrauterine infusion, or left as untreated controls. Treatment occurred 24-42 days before the planned start of mating (PSM) within each herd. In addition, the reproductive tracts of 91 cows from 4 herds were examined using a vaginal speculum and rectal palpation and cervical-os discharge was scored on a scale from 0 (nil) to 3 (purulent). RESULTS: Overall, more treated cows were retained in the trial herds until pregnancy testing than control cows (p0.05). Average 28-day submission rate was higher (93.1% vs 87.1%; p0.05) and PSM-to-first-service interval was shorter (9+/-1 vs 11+/-1 days; p0.05) in treated than control cows. The percentage of cows not pregnant at the end of the mating period was not affected by treatment overall. However, amongst cows diagnosed with RFM, a dead calf, or vulval discharge, pregnancy rates 28 and 56 days after PSM were higher for treated than control cows (p0.05). Cows with a purulent cervical-os discharge had lower 28-day submission rates (p0.01), lower 28-day pregnancy rates (p0.05) and higher non-pregnant rates at the end of mating than cows with nil or mucoid cervical-os discharges. CONCLUSIONS: Intrauterine treatment with 0.5 g cephapirin improved reproductive performance of dairy cattle, especially those that had a history of RFM, a calf dead at calving or within 24 h of calving, or a vulval discharge.  相似文献   

10.
Ovarian follicular dynamics and estrous synchronization after Gonadotropin-releasing hormone (GnRH) treatment at Controlled Internal Drug Releasing device (CIDR) insertion were investigated in Japanese Black cows. CIDR was inserted for eight cows at 7 days after estrus. Cows were allocated to either Group A: 8-day CIDR insertion with GnRH treatment on d 0 (n=4, d 0=CIDR insertion) or Group B: 8-day CIDR insertion (n=4). Both groups were injected with prostaglandin F2alpha (PGF2alpha) on d 7. Ultrasonography and blood sampling were performed twice daily. Intensive sampling was performed every 15 min for 8 hr to determine the pulsatile release of LH on d -1, d 5 and d 10. Three of four cows showed intermediate ovulation within 2 days after GnRH treatment during CIDR insertion in Group A, whereas no ovulation was found in Group B. Three of four cows in Group A and all four cows in Group B ovulated after CIDR removal. Plasma progesterone concentrations from d 3 to d 7 in three intermediate ovulatory cows in Group A (8.4 +/- 1.6 ng/ml) was significantly higher than those in Group B (4.1 +/- 1.2 ng/ml; 4 cows) during CIDR insertion (P<0.01). Interval to estrus and ovulation after CIDR removal was observed at 60.0 +/- 12.0 hr and 76.0 +/- 6.9 hr in three cows in Group A, and 75.0 +/- 15.1 hr and 93.0 +/- 20.5 hr in Group B, respectively. There was a significant increase in LH pulse frequency on d 10 compared on d -1 or d 5 in both groups (P<0.05), in addition those on d 10 in Group A tended to be higher than in Group B. As a result, GnRH treatment at CIDR insertion at 7 days after estrus induced intermediate ovulation with formation of corpus luteum (CL) and rather synchronized emergence of ovulatory follicle during CIDR insertion. These induced CL increased plasma progesterone concentrations and contributed to precise synchronization.  相似文献   

11.
ABSTRACT

Aims: To assess the change in body condition score (BCS) during the early and late dry periods and its association with postpartum diseases and milk yield in grazing dairy cows from central Argentina.

Methods: BCS assessments during the dry period, and cow health and milk production records up to 90 days in milk (DIM), were collated for cows from 28 farms at monthly visits between 2007 and 2008. Cows were categorised into four groups; those in Group 1 (n=7,067) maintained or gained BCS during the early and late dry periods; Group 2 (n=2,615) maintained or gained BCS during the early dry period and lost BCS during the late dry period; Group 3 (n=1,989) lost BCS during the early dry period and maintained or gained BCS during the late dry period; and Group 4 (n=5,144) lost BCS during the early and late dry periods.

Results: Cows in Group 1 had reduced odds of having retained fetal membranes (RFM), metritis, and clinical mastitis up to 90 DIM than cows in Group 2 (p<0.001), but the odds of disease were similar to cows in Group 3. The odds of having RFM or clinical mastitis tended to be lower in cows in Group 1 than cows in Group 4 (p=0.08). The odds of cows being culled or dying during the first 90 DIM were lower for cows in Group 1 than for those in Groups 2, 3, and 4 (p≤0.05). Mean accumulated milk yield up to 90 DIM was higher in cows in Group 1 than Group 2 and Group 4 (p<0.001), but was similar to that of cows in Group 3 (p=0.28).

Conclusions and clinical relevance: Cows that lost BCS during the late dry period had increased odds of being diagnosed with several postpartum diseases and had decreased milk yield compared to cows that maintained or gained BCS during the entire dry period. Loss of BCS during any stage of the dry period was also associated with increased incidence of culling or death during the first 90 DIM. These results should raise awareness among dairy cattle producers of the importance of properly managing cow body condition during the dry period, especially during the late dry period.  相似文献   

12.
The objective of this study was to investigate the effect of intrauterine infusion with liquid paraffin (LP) on phagocytic migration into the uterus of cows. Smears of swab samples of the external os of the cervix and discharges collected inside the vagina were obtained in multiparous dairy cows (n = 10) that had been infused with 50 ml of LP (LP group: n = 5) or physiological saline (PS group: n = 5) on day 10 or 11 after ovulation (day 0: ovulation). The samples were collected for cytological examination 0 (just before), 0.25, 1, 2, 3, 4, 6, 8, 12 and 24 h after LP or PS infusion and then at daily intervals until subsequent ovulation. The number of neutrophils increased significantly (p < 0.05) for 8 days compared with the pre-infusion level in the LP group and for 2 days in the PS group. The average numbers of neutrophils in the LP group were significantly (p < 0.05) greater than those in the PS group on 3, 4, 5 and 8 days after infusion. The number of monocytes from 6 h to 8 days after LP infusion was significantly higher than that before infusion (p < 0.05). The average numbers of monocytes at 4 and 6 h and 1 day after infusion in the LP group were significantly higher than those in the PS group. These findings indicate that LP stimulates phagocytic migration into the uterine lumen in cows and that LP infusion into the uterus might enhance uterine defence mechanisms during uterine infection.  相似文献   

13.
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.  相似文献   

14.
We conducted a progesterone-based timed AI protocol after follicular fluid aspiration using the ovum pick-up (OPU) technique to examine its applicability to the suckled beef cow. A total of 19 beef cows were randomly allocated to one of the following three groups based on the number of days postpartum: 13 to 60 days (Group A: suckled; early postpartum period, n=9), 61 to 150 days (Group B: suckled; mid postpartum period, n=6), or 151 to 281 days (Group C: non-suckled; prolonged open period, n=4) postpartum. These cows were treated with follicular fluid aspiration and insertion of a progesterone-releasing intravaginal device (PRID) on day 0. The PRID was removed and 500 microg of cloprostenol was intramuscularly administered on day 7. A dose (100 microg) of fertirelin acetate was injected intramuscularly 48 hours later, and this was followed by a timed AI (TAI) after another 18 hours (day 10). Serum samples were taken on days 0, 7, 9, 10, 12, 17, 24 and 31 for determination of the estradiol-17beta (E(2)) and progesterone concentrations. Pregnancy diagnosis was made by rectal palpation approximately 60 days after TAI. There was no significant difference in the peripheral E(2) concentrations among the three groups during the period of the hormonal treatment. The average progesterone concentrations in Group A on day 17 were significantly higher than those in Group B and exceeded 1.0 ng/ml on day 17 and thereafter. There was no significant difference in the numbers of collected immature oocytes among the three groups. The pregnancy rates in Groups A, B, and C were 77.8% (7/9), 83.3% (5/6) and 50.0% (2/4), respectively. In conclusion, this timed AI protocol is applicable to suckled beef cows within the period of 60 days postpartum.  相似文献   

15.
Twenty-eight Hereford x Angus cows (4 yr of age) were used to determine the effects of pre- and postpartum dietary energy on performance and reproductive function in suckled beef cows. The experiment was designed as a 2 x 2 factorial with cows receiving either 70 (L) or 150% (H) of NRC recommended level of dietary energy before and(or) after parturition, resulting in four treatment combinations (L-L, L-H, H-L, H-H). Prepartum diets were fed for approximately 110 d, and postpartum diets were fed until either 10 d after the second postpartum ovulation or 150 d postpartum for those cows that failed to ovulate. Cows receiving low compared with high levels of energy before calving lost more (P less than .01) weight, body condition, subcutaneous fat, and longissimus muscle area before parturition and had calves with lighter (P less than .01) birth weights. Cows receiving low compared with high levels of energy postpartum lost more (P less than .01) weight, body condition, and longissimus muscle area after parturition. Low levels of energy before and after parturition decreased (P less than .01) milk production and calf weight at 70 d of age. Rates of cervical and uterine involution were unaffected by dietary energy treatments. Cows receiving high levels of energy prepartum had increased (P less than .01) mean concentrations and pulse frequency of LH in serum after parturition, and cows receiving high levels of energy postpartum had increased (P less than .05) pulse frequency of LH. Low levels of energy postpartum decreased (P less than .01) appearance rate of small (5.0 to 7.9 mm) and large (greater than or equal to 10 mm) follicles, and low levels of energy prepartum decreased (P less than .02) appearance rate of large follicles based on transrectal ultrasonography. Cows receiving high levels of energy prepartum had shorter (P less than .02) intervals from parturition to ovulation, and a higher (P less than .01) percentage of the cows that received high levels of energy postpartum ovulated by 150 d postpartum. In summary, prepartum level of dietary energy influenced birth weight and weight gain of calves, milk production, concentrations and pulse frequency of LH in serum, appearance rate of large follicles, and the interval to first ovulation. Postpartum level of dietary energy influenced milk production, weight gain of calves, pulse frequency of LH, appearance rate of small and large follicles, and the percentage of cows that ovulated after parturition.  相似文献   

16.
The postpartum uterine bacteriology, histology, resumption of ovarian activity and polymorphonuclear granulocyte (PMN) number and function in 18 Swedish dairy cows were studied. Cows were milked either 2x (n = 9) or 3x per day (n = 9). Endometrial biopsy samples for bacteriological and histological investigations were collected during 8 weeks postpartum, starting within one week after calving. Milk samples for progesterone determination were collected twice a week until the cows had shown normal reproductive cyclicity. Blood samples for granulocyte function (phagocytic capacity and total number) were collected from each animal on the same days as when the biopsies were obtained. All animals in both groups were free from bacteria at the latest after 6 weeks post-partum and there was no difference regarding bacterial elimination and bacterial species between milking groups. No difference regarding uterine histology between milking groups was seen. In both groups, 8 cows had normal to slight infiltration of leukocytes in the endometrium at the end of sample collection. No changes in granulocyte function could be seen in the 2 milking groups. Resumption of ovarian activity was detected on day 45.6 +/- 9.3 (mean +/- SD) postpartum in the 2x milking group and 36.6 +/- 9.0 (mean +/- SD) post-partum in the 3x milking group (p = 0.05). Based on our findings, an increased milking frequency from 2 to 3 times a day did not influence the uterine function postpartum.  相似文献   

17.
The objectives were to investigate the relationships between endometrial cytology (EC) and interval from calving to first ovulation, and pregnancy in dairy cows, and that between uterine fluid and EC. On day 25 postpartum, 39 dairy cows were grouped based on EC, as having low (?8%) or high (>8%) polymorphonuclear cells (PMN), and the quantity of uterine fluid was assessed by ultrasound. The interval from calving to first ovulation was shorter in low, than in high PMN cows (32 vs. 45 d). A greater proportion of cows with uterine fluid had high PMN (64% vs. 21%), and the PMN increased from 14% to 34% as the quantity of uterine fluid increased. The mean interval from calving to ovulation was longer in primiparous cows with high PMN (49 d) compared to that of primiparous and multiparous cows with low PMN (28 and 29 d, respectively). Although the conception rate to first service at 92 d postpartum was not different between PMN groups, the cumulative pregnancy at 270 d tended to be higher in low than in high PMN (80% vs. 58%) multiparous cows. Also, cows that had uterine fluid on day 25 postpartum had a shorter interval from calving to pregnancy than those with no uterine fluid (161 vs. 208 d). In conclusion, combining transrectal ultrasonography with endometrial cytology on day 25 postpartum has diagnostic value in the assessment of uterine inflammation.  相似文献   

18.
The influences of body condition score (BCS) at calving and postpartum nutrition on endocrine and ovarian functions, and reproductive performance, were determined by randomly allocating thin (mean BCS = 4.4 +/- 0.1) or moderate condition (mean BCS = 5.1 +/- 0.1) Angus x Hereford primiparous cows to receive one of two nutritional treatments after calving. Cows were fed to gain either 0.45 kg/d (M, n = 17) or 0.90 kg/d (H, n = 17) for the first 71 +/- 3 d postpartum. All cows were then fed the M diet until 21 d after the first estrus. A replication (yr 2; M, n = 25; H, n = 23) was also used to evaluate reproductive characteristics. Concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were quantified in plasma samples collected weekly during treatment and during 7 wk before the first estrus. Estrous behavior was detected by radiotelemetry, and luteal activity was determined based on concentrations of progesterone in plasma. All cows were bred by AI between 14 and 20 h after onset of estrus, and pregnancy was assessed at 35 to 55 d after AI by ultrasonography. Cows that calved with a BCS of 4 or 5 had similar endocrine function and reproductive performance at the first estrus. During treatment, H cows gained BW and increased BCS (P < 0.01), and had greater (P < 0.05) concentrations of IGF-I, leptin, insulin, glucose, and thyroxine in plasma than M cows. However, during the 7 wk before the first estrus, plasma concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were not affected by time. Cows previously on the H treatment had a shorter (P < 0.01) interval to first postpartum estrus and ovulation, and a larger dominant follicle (P < 0.01) at first estrus, than M cows, but duration of estrus and the number of mounts received were not influenced by nutrient intake. Pregnancy rate at the first estrus was greater (P < 0.03) for H (76%, n = 38) than for M (58%, n = 33) cows. Increased nutrient intake after calving stimulated secretion of anabolic hormones, promoted fat deposition, shortened the postpartum interval to estrus, and increased pregnancy rate at the first estrus. Concentrations of IGF-I and leptin in plasma were constant during 7 wk before the first estrus, indicating that acute changes in these hormones are not associated with the resumption of ovarian function in primiparous beef cows.  相似文献   

19.
The aim of this study was to examine whether the nutritional state of cows peripartum was associated with the recovery of ovarian function and conception rates after synchronization of ovulation and fixed-time artificial insemination (OVSYNCH/TAI). The effect of the interval in days from calving to the first ovulation on conception rates after OVSYNCH/TAI was also investigated. Conception rates of cows after OVSYNCH/TAI (n=39) were 43.6%. The conception rates of cows with a body condition score (BCS) of 2.75-3.25 at 30 d postpartum and on the day of OVSYNCH treatment were significantly higher than in cows with a BCS < or =2.5 (P<0.05). The percentage of cows establishing ovarian cyclicity before 55 d postpartum in cows with a BCS of 2.75-3.25 at 30 d postpartum and on the day of OVSYNCH treatment were significantly higher than in cows with a BCS < or =2.5 (P<0.05). The conception rates after OVSYNCH/TAI in cows which recovered ovarian cyclicity within 34 d postpartum were significantly higher than in cows with first ovulation > or =56 d (P<0.05). These results indicated that the nutritional state in cows peripartum influenced the conception rates after OVSYNCH/TAI and the postpartum ovarian cyclicity and also suggested that the conception rates after OVSYNCH/TAI decreased in cows with delayed recovery of ovarian cyclicity.  相似文献   

20.
The effect of two insemination policies after synchronization of oestrus on reproductive performance in two groups of cows was investigated. Oestrus was synchronized by two treatments with prostaglandin F2 alpha (PGF2 alpha) at a 14-day interval. Cows in Group 1 (n = 234) were inseminated twice on appointment 66 and 90 h after the second treatment. Cows in Group 2 (n = 222) were intensively watched for signs of oestrus after the synchronization protocol and inseminated on observed oestrus. Cows with abnormal discharge after synchronization were excluded from breeding and inseminated later during the study period. Service rate within 1 week after synchronization was higher in Group 1 than in Group 2 (89.3 versus 67.1%). Conception rates on first service did not differ between groups (33.2 versus 30.0%). Days to first service and days open were shorter in Group 1 (P < 0.05). The number of cows culled for infertility did not differ between the groups. Endometritis 14-20 days post-partum decreased the percentage of cows pregnant at the end of the study period in both groups but did not have a significant effect on conception rates and days open. It is concluded that additional inseminations required in the timed artificial insemination protocol were economically justified by the reduction in days open in comparison with insemination on observed oestrus after synchronization.  相似文献   

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