scholarly journals SHORT-TERM FEEDING OF MELENGESTROL ACETATE PLUS GnRH AND PGF2α TO ENHANCE REPRODUCTIVE EFFICIENCY OF REPLACEMENT DAIRY HEIFERS

2014 ◽  
Vol 51 (3) ◽  
pp. 156-163
Keyword(s):  
Reproductive Efficiency ◽  
Short Term ◽  
Dairy Heifers ◽  
Melengestrol Acetate

Fertility of inseminations with two sperm concentrations in oestrus-synchronized cattle

1973 ◽  
Vol 17 (2) ◽  
pp. 163-168
Author(s):  
L. J. Boyd ◽  
G. F. Smith ◽  
P. D. P. Wood ◽  
J. Craven ◽  
D. R. Melrose ◽  
...  
Keyword(s):  
Field Trials ◽  
Return Rate ◽  
Breeding Period ◽  
Dairy Herds ◽  
Dairy Heifers ◽  
Melengestrol Acetate ◽  
Beef Herds ◽  
Live Sperm ◽  
And Control

SUMMARYTwo field trials were conducted to evaluate oestrus synchronization under farm conditions and to determine if increased sperm numbers per insemination would enhance fertility at the first synchronized oestrus. One hundred and seventy-seven previously unmated British Friesian females in 6 dairy herds and 236 suckler cows in 9 beef herds were used. Treated animals received 1·0 mg melengestrol acetate (MGA) daily for 14 days. Treated and control animals were inseminated with either 15 or 60 million sperm per first insemination.Oestrus was synchronized in 94% of the treated dairy heifers and 66% of the treated suckler cows. Oestrus detection by herdsmen appeared to be much less precise in suckler herds than in the dairy herds.First inseminations were given during a 21-day breeding period (commencing at withdrawal of MGA) to 97% of treated and 79% of control dairy heifers (P<0·01), and to 77% of the treated and 69% of the control suckler cows (P>0·05). On an average, first inseminations were given 10 days earlier to treated heifers and 7 days earlier to treated suckler cows than to their control counterparts. The 45-day non-return rate to first inseminations was 81% for control and 41% for treated dairy heifers (P< 0·001) and 69% for control and 46% for treated suckler cows (P>0·05).Oestrus-synchronized animals required significantly more services than control animals during a 30-day breeding period. However, there was no difference between treated and control animals in the non-return rate to one or more services given during the prescribed 30-day breeding period.Insemination with 15 or 60 million live sperm had no effect on the non-return rate of treated or control animals.

scholarly journals Impairment of zebrafish reproduction upon exposure to melengestrol acetate

2017 ◽  
Author(s):  
Kewen Xiong ◽  
Chunyun Zhong ◽  
Xin Wang
Keyword(s):  
Endocrine Disruption ◽  
Endocrine Disruptor ◽  
Egg Production ◽  
Control Fish ◽  
Fish Reproduction ◽  
Short Term ◽  
Melengestrol Acetate ◽  
Short Term Exposure ◽  
Female Zebrafish ◽  
Hatching Rates

AbstractSynthetic progestins contamination is common in the aquatic ecosystem, which may lead to serious health problem on aquatic animals. Melengestrol acetate (MGA) has been detected in the aquatic environment; however, its potential effects on fish reproduction are largely unclear. Here, we aimed to investigate the endocrine disruption and impact of MGA on zebrafish reproduction. Six-month old reproductive zebrafish were exposed to four nominal concentrations of MGA (1,10, 100 and 200 ng/L) for 15 days. Treatment with MGA reduced the egg production with a significant decrease at 200 ng/L. The circulating concentrations of estradiol and testosterone in female zebrafish or 11-keto testosterone in male zebrafish were significantly diminished compared to the non-exposed control fish. The early embryonic development or hatching rates were unaffected during the MGA exposure. Our results indicated that MGA was a potent endocrine disruptor in fish and the fish reproduction could be impaired even during a short-term exposure to MGA.

Effect of Melengestrol Acetate on Rate of Excretion of Estrogen in Urine of Dairy Heifers

1973 ◽  
Vol 36 (4) ◽  
pp. 741-748 ◽  
Author(s):  
R. D. Randel ◽  
C. J. Callahan ◽  
R. E. Erb ◽  
H. A. Garverick ◽  
B. L. Brown
Keyword(s):  
Dairy Heifers ◽  
Melengestrol Acetate

80 Relationship between anogenital distance and reproductive efficiency of embryo recipient dairy heifers

2022 ◽  
Vol 34 (2) ◽  
pp. 276
Author(s):  
A. Garcia-Guerra ◽  
R. Sala ◽  
L. Carrenho-Sala ◽  
F. Valencia ◽  
M. Fosado ◽  
...  
Keyword(s):  
Reproductive Efficiency ◽  
Anogenital Distance ◽  
Dairy Heifers

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

scholarly journals Sward structure and short-term herbage intake in Arachis pintoi cv. Belmonte subjected to varying intensities of grazing

2017 ◽  
Vol 156 (1) ◽  
pp. 92-99 ◽  
Author(s):  
G. P. Silva ◽  
C. A. Fialho ◽  
L. R. Carvalho ◽  
L. Fonseca ◽  
P. C. F. Carvalho ◽  
...  
Keyword(s):  
Nutritive Value ◽  
Block Design ◽  
Intake Rate ◽  
Short Term ◽  
Tropical Pastures ◽  
Dairy Heifers ◽  
Bite Rate ◽  
Sward Height ◽  
Herbage Intake ◽  
Sward Structure

AbstractThe use of forage legumes has been proposed as a means of generating sustainable grazing environments. Their limited use, particularly in tropical pastures, is partially due to the limited knowledge regarding the efficiency of utilization by animals. The present study characterized the sward structure, nutritive value and ingestive behaviour of dairy heifers in pastures of peanut cv. Belmonte under continuous stocking management. Treatments corresponded to sward heights of 5, 10, 15 and 20 cm, according to a randomized complete block design, with four replications. The following response variables were evaluated: vertical distribution of the morphological components within the sward, forage mass, nutritive value (simulated grazing), bite rate (BR), bite mass (BM) and short-term herbage intake rate (STIR). The top half of the sward height was mainly composed of leaves and the bottom half mainly of stolon and dead material regardless of management height. Greater values of neutral detergent fibre and acid detergent fibre were recorded during autumn, while higher values of in-vitro dry matter (DM) digestibility (0·85) occurred during spring regardless of management height for the grazed stratum. In relation to treatments, greater values of crude protein were recorded on swards managed at 5 cm (0·27) and 10 cm (0·26). Bite rate, BM and STIR varied with sward height, but not with a season of the year. The STIR followed a broken line response to sward height, with increasing values up to 13·1 cm (106 g DM/kg body weight). Sward structure played an important role in determining the STIR. To maximize the STIR of dairy heifers under continuous stocking management, swards should be managed at heights of not <13·1 cm.

Effect of Melengestrol Acetate on Plasma Progesterone, Luteinizing Hormone and Total Corticoids in Dairy Heifers

1972 ◽  
Vol 35 (2) ◽  
pp. 389-397 ◽  
Author(s):  
R. D. Randel ◽  
C. J. Callahan ◽  
R. E. Erb ◽  
H. A. Garverick ◽  
B. L. Brown
Keyword(s):  
Luteinizing Hormone ◽  
Plasma Progesterone ◽  
Dairy Heifers ◽  
Melengestrol Acetate

Effect of melengestrol acetate (MGA) treatment or temporary kid removal on reproductive efficiency in meat goats

2006 ◽  
Vol 66 (1-3) ◽  
pp. 253-257 ◽  
Author(s):  
D.J. Jackson ◽  
C.M. Fletcher ◽  
D.H. Keisler ◽  
N.C. Whitley
Keyword(s):  
Reproductive Efficiency ◽  
Melengestrol Acetate ◽  
Meat Goats
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