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

1983 ◽  
Vol 63 (2) ◽  
pp. 325-330 ◽  
Author(s):  
J. G. MANNS ◽  
W. D. HUMPHREY ◽  
J. R. NKUUHE
Keyword(s):  
Key Words ◽  
Beef Cows ◽  
Ovarian Activity ◽  
Moderate Increase ◽  
Short Term ◽  
Cyclic Activity ◽  
Estrous Cycles ◽  
Prostaglandin F ◽  
Calf Removal

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

Effect of short-term calf removal at three stages of a follicular wave on fate of a dominant follicle in postpartum beef cows.

2001 ◽  
Vol 79 (10) ◽  
pp. 2688 ◽  
Author(s):  
B E Salfen ◽  
F N Kojima ◽  
J F Bader ◽  
M F Smith ◽  
H A Garverick
Keyword(s):  
Beef Cows ◽  
Dominant Follicle ◽  
Short Term ◽  
Follicular Wave ◽  
Three Stages ◽  
Calf Removal

Influence of PMSG antiserum on serum progesterone and estrous cycles of PMSG-treated gilts

1992 ◽  
Vol 72 (1) ◽  
pp. 173-176 ◽  
Author(s):  
R. N. Kirkwood ◽  
P. A. Thacker
Keyword(s):  
Key Words ◽  
Luteal Phase ◽  
Ovarian Activity ◽  
Serum Estradiol ◽  
Serum Progesterone ◽  
Estrous Cycles ◽  
Blood Samples ◽  
Effect Of Treatment

Forty-seven prepubertal gilts (88.4 ± 0.9 kg) received an injection of 750 IU PMSG to stimulate ovarian activity. After 96 h, 23 gilts received an injection of an anti-PMSG serum. Blood samples were obtained at the time of PMSG injection (day 0) and at 2, 4, 6, 11, 18, 25 and 32 d. There was no effect of treatment on serum estradiol concentrations or on the occurrence of normal estrous cycles. However, luteal phase serum progesterone concentrations were higher (P < 0.01) in gilts receiving the anti-PMSG. Key words: PMSG, antiserum, gilts, ovulation

Melengestrol acetate, estradiol-17β and GnRH for synchronization of estrus and ovulation in beef cows

1999 ◽  
Vol 79 (1) ◽  
pp. 39-43 ◽  
Author(s):  
J. Thundathil ◽  
J. P. Kastelic ◽  
W. O. Olson ◽  
R. B. Cook ◽  
R. J. Mapletoft
Keyword(s):  
Key Words ◽  
Pregnancy Rate ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Conception Rate ◽  
Estrus Synchronization ◽  
Short Term ◽  
Melengestrol Acetate ◽  
Conception Rates ◽  
Estradiol 17Β

Three experiments were conducted with suckled crossbred beef cows to determine the efficacy of various short-term regimens for synchronizing estrus or ovulation and to determine whether feeding melengestrol acetate (MGA) after timed AI will increase pregnancy rate. In exp. 1, all cows (n = 141) were given 0.5 mg MGA head−1 d−1 for 7 d (days 1 to 7), 1 or 5 mg E17β (and 100 mg progesterone) or 100 µg GnRH on day 1, and 500 µg cloprostenol on day 7. There were no significant differences among groups for estrous or synchronized conception rates (average, 84.4 and 52.1%, respectively). With an identical protocol in exp. 2 (78 cows), by day 11, cows given 5 mg E17β had the highest estrous and synchronized pregnancy rates (65.4 and 42.3%), compared to 1 mg E17β (46.2 and 15.4%) and GnRH (34.6 and 11.5%). Cows not detected in estrus were timed-inseminated and given 100 µg GnRH, 100 h after cloprostenol. There were no significant differences among groups for synchronized conception rate to timed AI (65.0%) or synchronized pregnancy rate to all inseminations (56.4%). Overall, 5 mg E17β gave the most consistent results. In exp. 3, 84 cows were given 100 µg GnRH on days 1 and 9, 500 µg cloprostenol on day 7, and were timed-inseminated on day 10. Half were fed MGA (0.5 mg head−1 d−1) on days 16 to 22, but the pregnancy rate was not different from that in the remaining cows (55.0 versus 47.8%, P > 0.5). Key words: Ovary, follicles, estrus synchronization, beef cows

FAILURE OF EXOGENOUS PROSTAGLANDIN F2α TO ENHANCE UTERINE INVOLUTION IN BEEF COWS

1988 ◽  
Vol 68 (3) ◽  
pp. 669-676 ◽  
Author(s):  
L. A. GUILBAULT ◽  
P. VILLENEUVE ◽  
J. J. DUFOUR
Keyword(s):  
Plasma Concentrations ◽  
Prostaglandin F2α ◽  
Physiological Saline ◽  
Beef Cows ◽  
Tissue Loss ◽  
Primary Metabolite ◽  
Descending Aorta ◽  
Uterine Involution ◽  
Prostaglandin F ◽  
Calf Removal

Twenty-four beef cows of 5th parity were fitted with catheters in the descending aorta via a superficial costoabdominal artery. On the day of parturition (day 0), cows were assigned randomly and equally to two infusion treatments and three slaughter groups. Cows were infused continuously for 11 d with either prostaglandin F2α-tham salt (PGF2α; 33.5 mg d−1 from days 2 to 13) or 0.9% physiological saline (saline) via the descending aorta. In the first slaughter group, cows were suckled until slaughtered on day 15. Cows in the second slaughter group were suckled until slaughtered on day 35; whereas in the third group, calves were weaned on day 31 and cows slaughtered on day 35. Reproductive tracts were collected at slaughter and degree of uterine involution was assessed by recording weight and diameter of the cervix, weight, diameter and length of both uterine horns as well as surface areas of caruncular and intercaruncular endometrium. During the infusion period, plasma concentrations of 15-keto-13, 14-dihydro-PGF2α, the primary metabolite of PGF2α, were higher in PGF2α- than in saline-infused cows (1091 vs 738 pg mL−1, SE = 105, P < 0.03). All cervical and uterine (except uterine horn diameter) measures of involution were greater (P < 0.1) on day 15 than on day 35. Calf removal did not affect (P > 0.1) uterine involution on day 35. None of the responses measured to assess uterine involution differed (P > 0.1) between PGF2α- and saline-infused cows on day 15 or 35. It is concluded that early postpartum administration of PGF2α by continuous infusion does not alter uterine involution in terms of reduction in size and tissue loss by days 15 and 35 postpartum. Key words: Cows, postpartum, prostaglandin F2α, uterine involution.

REPRODUCTIVE PERFORMANCE OF HORMONALLY TREATED SHEEP MAINTAINED YEAR-ROUND IN A CONTROLLED-LIGHT ENVIRONMENT

1982 ◽  
Vol 62 (4) ◽  
pp. 1109-1117 ◽  
Author(s):  
A. J. HACKETT ◽  
H. A. ROBERTSON ◽  
H. A. ROBERTSON ◽  
R. J. DWYER ◽  
M. S. WOLYNETZ
Keyword(s):  
Key Words ◽  
Reproductive Performance ◽  
Similar Pattern ◽  
Treatment Effects ◽  
Hormone Treatment ◽  
Breeding Program ◽  
Light Environment ◽  
Day Length ◽  
Ovarian Activity ◽  
Prostaglandin F

Six experiments were conducted on hormonally treated ewes maintained year-round in a controlled-light environment in a breeding program designed to produce three lamb crops in 2 yr. Various combinations of fluorogestone acetate (FGA), prostaglandin F2α (PGF2α) and pregnant mares' serum gonadotrophin (PMSG) were used to synchronize estrus in the ewes. There were no significant differences (P > 0.05) in fertility between FGA- and PGF2α-treated ewes when the ewes were having cyclic ovarian activity (cycling) at the time of treatment, i.e. in January and May in our system. Among ewes in the constant day-length lighting regime, fertility was lower in September than in January or May. Prolificacy ranged from 1.7 to 2.0 in the six experiments. Fecundity, a measure of the overall productivity, followed a similar pattern to fertility and was not significantly (P > 0.05) affected by the various treatments. These findings demonstrated the feasibility of maintaining a controlled 8-mo breeding program for sheep maintained year-round in a controlled-light environment. Key words: Reproduction in sheep, controlled light, hormone treatment effects.

Techniques for estimation of milk yield in beef cows and relationships of milk yield to calf weight gain and postpartum reproduction.

1990 ◽  
Vol 68 (4) ◽  
pp. 937-943 ◽  
Author(s):  
W. E. Beal ◽  
D. R. Notter ◽  
R. M. Akers
Keyword(s):  
Weight Gain ◽  
Milk Production ◽  
Milk Yield ◽  
Beef Cows ◽  
Milk Composition ◽  
Ovarian Activity ◽  
Machine Milking ◽  
Calf Removal ◽  
On Farm ◽  
Fall Calving

Abstract Milk production is a primary factor controlling weaning weight of beef calves. The purpose of this experiment was to develop a practical and reliable on-farm method of estimating milk production and to relate estimates of milk production and milk composition to preweaning weight gain of calves. A second objective was to relate milk production to postpartum ovarian activity. Milk production of spring- and fall-calving grade Angus cows was estimated by machine milking (MM; average of 66, 123 and 189 d postpartum) and weigh-suckle-weigh (WSW; average of 50, 95, 136 and 179 d postpartum) techniques following overnight calf removal. Cows and calves were weighed monthly and the postpartum interval to first ovulation following calving was determined. The repeatability of the estimated milk production by MM (.97) was higher (P < .01) than by WSW (.35). The correlation of average WSW and average MM estimates of milk production with preweaning calf gain were high and similar (> .75). Inclusion of milk composition did not improve the multiple correlation of MM-estimated milk production and calf gain. Neither milk production in early lactation (−.06) nor prebreeding weight change (−.07) was correlated with postpartum interval to ovulation. Machine milking was a repeatable method of estimating milk production of beef cows and can be used to evaluate effects of management variables on lactation of beef cows.

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