Induction of ovulation with GnRH and PGF2a in lactating Bos taurus × Bos indicus cows

2004 ◽  
Vol 52 (4) ◽  
pp. 501-508 ◽  
Author(s):  
C. Ahuja ◽  
F. Montiel

Induction of ovulation for timed artificial insemination (TAI) with the Ovsynch protocol was evaluated in 49 anoestrous and lactating Bos taurus × Bos indicus cows. Palpation per rectum and transrectal ultrasonography were used on Days -30, -20, -10 and 0 (start of treatment) to confirm anoestrus but with the presence of follicles = 10 mm, and every other day during treatment to determine ovarian activity. Cows were randomly assigned to: (1) Ovsynch (n = 24; Day 0, 200 µg GnRH; Day 7, 150 µg PGF2a; Day 9, 200 µg GnRH + TAI 16 to 20 h later) and (2) control (n = 25; no treatment). Rates of ovulation for the first GnRH injection, detection of a corpus luteum (CL) at PGF2a injection, pregnancy and induction of cyclicity were greater (P < 0.05) with Ovsynch. There was no effect of body condition score (P ? 0.05). In conclusion, the Ovsynch protocol was not effective in obtaining acceptable pregnancy rate for TAI, but it was effective for induction of cyclicity in anoestrous and lactating Bos taurus × Bos indicus cows under tropical conditions.

2021 ◽  
Vol 248 ◽  
pp. 104482
Author(s):  
Luiz Francisco Machado Pfeifer ◽  
Walvonvitis Baes Rodrigues ◽  
Eriklis Nogueira

1994 ◽  
Vol 45 (4) ◽  
pp. 795 ◽  
Author(s):  
H Hearnshaw ◽  
PF Arthur ◽  
R Barlow ◽  
PJ Kohun ◽  
RE Darnell

Post-weaning growth and body condition, puberty and pelvic size of 197 heifers comprising straightbred Hereford (HxH) and Brahman (BxB), first-cross (BxH) and back-cross (HxBH and BxBH) heifers were evaluated. The heifers were born over a 3 year period, and grazed improved and semi-improved pastures following weaning at Grafton, New South Wales. Prior to weaning, heifers had been reared by dams on three pasture systems (high, medium and low quality pastures). Heifers from low quality pre-weaning pasture had higher (P < 0.05) post-weaning liveweight gain than those from high and medium quality pastures. BxH heifers gained 71 g/day more (P < 0.05) than the mean gain of their contemporaries of the other genotypes, whose gains were similar, from weaning to either 26 or to 30 months of age. Liveweight at all ages was influenced by genotype x pre-weaning pasture system interaction. At 30 months of age, BxH heifers from high and medium pre-weaning pastures were the heaviest. At the same age, but from low quality pre-weaning pasture, heifers with crossbred dams (HxBH and BxBH) were the heaviest. Wither height depended significantly (P < 0.05) on the proportion of Bos indicus genes, increasing from 113.8 cm in the HxH heifers to 124.4 cm in the BxB heifers at 30 months of age. BxH heifers had a higher (P < 0.05) body condition score than their contemporaries of the other genotypes, which were in similar condition, at 26 and 30 months of age. On average (across pre-weaning pasture system), 9% of BxB heifers had reached puberty by 22 months of age compared to 62, 95, 82 and 64% (s.e.= 9) for HxH, HxBH, BxH and BxBH heifers respectively. No significant genotype differences were obtained in the height, width and size of the pelvic opening of the heifers, measured just prior to the beginning of the mating season at 26 months of age.


1993 ◽  
Vol 44 (5) ◽  
pp. 1079 ◽  
Author(s):  
CS McSweeney ◽  
PM Kennedy ◽  
MJ D'Occhio ◽  
LA Fitzpatrick ◽  
D Reid ◽  
...  

Supplementation designed to increase the supply of glucose and amino acids, was compared with early weaning as strategies for reducing post-partum anoestrous in Bos indicusx Bos taurus (518x318) first-lactation heifers. Twenty-three pregnant heifers were allocated to four treatment groups and fed long-chopped hay (15.8 g N/kg dry matter) ad libitum and a complete mineral mixture throughout the experiment as well as 450 g molasses and 50 g urea per day during the final month of pregnancy. After calving, three groups were supplemented daily for 120 days with either 2 kg cracked rice (E), 0.4 kg formaldehyde-treated casein (P), or cracked rice (2 kg)+formaldehyde-treated casein (0.4 kg) (E+P); the unsupplemented control group had their calves weaned at 60 days post-partum. Supplemented animals had significantly higher intakes of hay (7- 1-7.3 v. 5.9 kg OM/day), weight gain (0.4-0.5 v. 0.0 kg/day) and body condition score (4.6-4.7 v. 4.3) than the unsupplemented heifers, but there were no differences between the supplemented groups in these variables. Unsupplemented animals and heifers fed P partitioned similar amounts of lactose and fat into milk, whereas secretion of both lactose and protein was significantly higher in the E+P and E groups. All control heifers ovulated within 14 days of their calves being weaned, whereas only two of the lactating supplemented heifers (EfP) showed cyclic ovarian activity at that time and three other lactating heifers ovulated several weeks later. The response to weaning occurred in heifers that had a liveweight and condition score of 374 kg and 4.3 respectively, which was 30-50 kg and a half unit in condition below the suckling heifers. In unsupplemented heifers showing ovarian cyclicity, acetate entry rate was less than half that of the supplemented animals, whereas glucose entry rate, adjusted for loss to lactose, was similar for both groups. Supplementation did not affect either the basal concentration or frequency of pulsatile release of luteinizing hormone (LH) at 60 days post-partum, or the LH response to gonadotrophin releasing hormone (5 8g GnRH). It is concluded that under the conditions of the present study, weaning had a greater effect than post-partum nutritional supplements on the resumption of ovarian activity in first-lactation heifers with moderate nutrition.


2010 ◽  
Vol 9 (1) ◽  
pp. 79-84 ◽  
Author(s):  
F. Escobedo-A ◽  
M.G.J. Nuncio-Och ◽  
J. Herrera-Ca ◽  
B. Gomez-Ramo ◽  
J.C. Segura-Cor ◽  
...  

2016 ◽  
Vol 56 (11) ◽  
pp. 1810
Author(s):  
J. Galindo ◽  
S. Estrada ◽  
C. S. Galina ◽  
R. Molina ◽  
D. A. Contreras ◽  
...  

To evaluate the effect of an energy supplementation, 26 postpartum Bos indicus cows were assigned either to receive an energy diet supplementation (n = 11, SSD) or no supplementation (n = 15, NSSD). Cows in the SSD treatment received a diet consisting of 5.5% crude protein, 2.85 Mcal digestible energy per head per day, at 1% ratio of the average bodyweight, started 23.5 ± 3.4 days after calving and continued for 44 days. In contrast, NSSD cows were grazing only native pastures during the experiment. All cows were synchronised at 65 days postpartum with a subcutaneous progestin ear implant (Norgestomet) for 9 days and an injection of oestradiol valerate and Norgestomet at the same time as implant placement. A random sample of six animals from each treatment was scanned with ultrasound every 6 h and the dominant follicle (s) was measured until ovulation occurred or after 114 h. The nadir of body condition score for the NSSD was observed at 37.5 ± 3.4 days postpartum, while SSD was at 22.3 ± 7.9 days (P < 0.01); no differences (P > 0.05) in dorsal backfat thickness or average bodyweight between treatments were observed. During the ultrasound-scanning period, four of six cows ovulated in the SSD treatment and five of six in the NSSD. No difference (P > 0.05) was observed at the time of ovulation after progestin implant withdrawal (55.8 ± 7.8 h in NSSD vs 94.5 ± 21.7 h in SSD). The largest follicle diameter at the beginning of the scanning was in SSD treatment (7.25 ± 1.4 mm in SSD vs 5.0 ± 0.8 mm in NSSD), whereas at the time of ovulation, it was similar (15.2 ± 1.8 mm in SSD vs 11.0 ± 1.4 mm in NSSD) between the treatments (P > 0.05). The resumption of ovarian activity was similar between SSD (69 ± 20.7 days, ranging from 42 to 83 days) and NSSD (69.8 ± 6.4 days, ranging from 59 to 73 days). The length of postpartum anoestrus was influenced by the onset of the nadir of body condition score. Energy diet supplementation did not influence the onset of ovarian activity.


2010 ◽  
Vol 22 (1) ◽  
pp. 168 ◽  
Author(s):  
L. Cutaia ◽  
M. Ramos ◽  
P. Chesta ◽  
G. A. Bó

An experiment was designed to test the following hypotheses: (1) the administration of 400IU of eCG (Novormón, Syntex SA, Buenos Aires, Argentina) 14 days after fixed-time artificial insemination (FTAI) increases pregnancy rates in cross-breed Zebu × Bonsmara suckled cows synchronized with progesterone releasing devices (DIB 0.5, 0.5 g of progesterone, Syntex SA); and (2) pregnancy rates in cows treated with estradiol or GnRH, combined with a DIB device, are not different. Primiparous suckled cows (n = 260), between 60 and 120 days postpartum (DPP) and with a body condition score between 2.0 and 2.5 (1 to 5 scale) were used. At the beginning of the experiment (Day 0), all cows were examined by rectal palpation (only 11% had a CL), received a DIB device, and were randomly allocated to 1 of 3 treatment groups. Cows in the E2 group received 2 mg of estradiol benzoate (EB) intramuscularly (i.m.) at DIB insertion and those in the two GnRH groups received 100 μg of gonadorelin (GDR Gonasyn, Syntex SA) at the same time. On Day 7, DIB devices were removed and all cows received 500 μg of cloprostenol (Ciclase DL, Syntex SA) plus 400 IU of eCG (i.m.). Cows in the E2 group received 0.5 mg of estradiol cypionate (ECP, Cipiosyn, Syntex SA) and underwent FTAI administered by one technician, using semen from 1 of 2 bulls between 52 and 56 h later. Cows in the GnRH groups received a dose of 100 μg of gonadorelin (full GnRH group) or 50 μg of gonadorelin (1/2 GnRH group) at the time of the FTAI (52 to 56 h after DIB removal). Fourteen days after FTAI cows in the 3 groups were further subdivided (3 × 2 factorial) to receive or not 400 IU of eCG i.m. Pregnancy was determined 30 days after FTAI using real-time ultrasonography. Data were analyzed by logistic regression, taking into account the effect of the synchronization treatment, eCG or noteCG, 14 days after FTAI and sire used. No differences in pregnancy rates were found (P = 0.16) among treatment groups (E2: 39/87, 43.7%, full GnRH: 38/92, 41.3%, and 1/2 GnRH: 25/81, 30.9%). However, there was a significant (P = 0.02) effect of eCG treatment 14 days after FTAI (eCG: 60/127, 47.2% v. no eCG: 41/133, 30.8%). Furthermore, bull A (77/155, 47.1%) resulted in higher pregnancy rate (P = 0.009) than bull B (28/107, 26.2%), but there were no significant interactions between bull and synchronization treatment or eCG administration 14 days after FTAI (P > 0.1). We conclude that the application of 400 IU of eCG 14 days after FTAI increases pregnancy rates in suckled Bos taurus × Bos indicus primiparous cows with fair to poor body condition score synchronized with progesterone releasing devices. Furthermore, the use of estradiol ester or GnRH at DIB insertion and removal did not affect pregnancy rates.


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