11 Early Induction of Luteolysis in Fixed-Time Artificial Insemination Protocols Increases Fertility in Beef Cows

2018 ◽  
Vol 30 (1) ◽  
pp. 145
Author(s):  
J. B. Borges ◽  
A. B. Machado ◽  
E. Pradebon ◽  
M. Dias ◽  
M. Bernardi ◽  
...  
Keyword(s):  
Odds Ratio ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Binary Outcomes ◽  
Serum Progesterone ◽  
Ovulatory Follicle ◽  
Condition Score ◽  
Prostaglandin F ◽  
Intravaginal Device

Complete luteolysis is essential for pregnancy success in beef cows submitted to fixed-time AI (FTAI) protocols. The objective of this study was to evaluate the effect of prostaglandin F (PGF) administration on Day 7 compared with Day 8 of an FTAI protocol on serum progesterone (P4) concentration, oestrus behaviour, ovulatory follicle (OF) diameter, and pregnancy per AI (P/AI). A total of 469 nonlactating Angus cows [with corpus luteum (CL), n = 359 or without CL, n = 110], body condition score 2.9 ± 0.2 (1 to 5 scale), maintained on pasture were used. Cows received a 1-g progesterone-releasing intravaginal device (Reproneo; GlobalGen, Jaboticabal, Brazil) and 2 mg of oestradiol benzoate i.m. (Syncrogen; GlobalGen) on Day 0. On Day 7, animals were randomly allocated into 2 groups. Cows were treated with 500 μg of sodium cloprostenol, IM (Inducio; GlobalGen), on Day 7 (PGF7, n = 238) or Day 8 (PGF8, n = 231). Then, P4 devices were removed and 0.5 mg of oestradiol cypionate, IM (Cipion; GlobalGen) was injected in all females on Day 8. The FTAI was performed 48 to 52 h after P4 device removal. Females had sacral region painted with appropriate paint (TELL TAIL, GEA, Hamilton New Zealand) on Day 8 to detect expression of oestrus. Transrectal ultrasonography (7.5-MHz linear transducer, MediSono P3V, Wilmington, DE, USA) was performed on Day 0 to detect presence of CL, on Day 10 to measure OF diameter, and on Day 40 to diagnose pregnancy. Blood samples were collected on Days 8 and 10 to measure P4 serum concentration by radioimmunoassay. Oestrus behaviour and pregnancy rate were analysed as binary outcomes using logistic regression (Proc GLIMMIX, SAS; SAS Institute Inc., Cary, NC, USA). OF diameter and P4 concentration were submitted to analysis of variance (Proc GLIMMIX, SAS). The oestrus manifestation was greater (odds ratio = 2.9; P = 0.0002) in females of PGF7 group (91.6%; 218/238) than PGF8 group (78.8%; 182/231). The P/AI of cows that exhibited oestrus was 60.2% (241/400) v. 39.1% (27/69), resulting in higher chance (odds ratio = 2.4) of pregnancy associated with oestrus behaviour (P = 0.0014). Diameter of the OF did not differ (P = 0.0881) between PGF7 (11.7 mm) and PGF8 (11.3 mm). The P/AI was higher (P = 0.0034) for PGF7 (63.9%, 152/238) v. PGF8 (50.2%, 116/231). In group PGF7, P4 on Day 8 did not differ between pregnant (1.7 ng mL−1) and nonpregnant (1.9 ng mL−1) females. However, group PGF8 pregnant females had lower P4 concentration (2.6 ng mL−1) on Day 8 (P = 0.0005) than nonpregnant (3.4 ng mL−1) females. On Day 10, P4 did not differ between treatments (PGF7 = 0.11 ng mL−1 v. PGF8 = 0.09 ng mL−1) and did not affect fertility (P = 0.2515). According to results, OF diameter and P4 concentration on Day 10 were not influenced by the day of PGF administration; however, earlier PGF injection resulted in higher oestrus behaviour and increased fertility.

scholarly journals Evaluation of the 7 & 7 Synch and 7-day CO-Synch + CIDR ® protocols for estrus synchronization of beef cows prior to fixed-time artificial insemination with conventional or sex-sorted semen

2020 ◽  
Author(s):  
C.M. Andersen ◽  
R.C. Bonacker ◽  
E.G. Smith ◽  
C.M. Spinka ◽  
S.E. Poock ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Sexed Semen ◽  
Condition Score ◽  
Prostaglandin F ◽  
Activation Status

AbstractAn experiment was designed to compare the recently developed 7 & 7 Synch and the 7-day CO-Synch + CIDR protocols for synchronization of estrus among beef cows prior to fixed-time artificial insemination (FTAI) with conventional or sex-sorted semen. Bos taurus cows (n = 1538) were blocked based on age and days postpartum (DPP) and randomly assigned to protocol and semen type. Cows treated with the 7-day CO-Synch + CIDR protocol (n = 769) received administration of gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin) and insertion of a 1.38 g intravaginal progesterone releasing insert (CIDR) on Day -10, and administration of prostaglandin F2α (PG; 500 μg cloprostenol) coincident with CIDR removal on Day -3. Cows treated with 7 & 7 Synch (n = 769) received PG and insertion of CIDR on Day -17, GnRH on Day -10, and PG coincident with CIDR removal on Day -3. Estrus detection aids (Estrotect™) were applied to all cows on Day -3, and activation status was recorded at FTAI. Cows received FTAI 66 h after CIDR removal with either conventional (20 × 106 cells per unit) or sex-sorted (4 × 106 cells per unit; SexedULTRA 4M™) semen. A greater proportion of cows expressed estrus (P = 0.01) prior to FTAI following 7 & 7 Synch (82%; 629/769) compared with the 7-day CO-Synch + CIDR (64%; 492/769). Estrus expression was also affected by protocol × DPP (P = 0.0004), with 7 & 7 Synch resulting in a greater increase in the proportion of cows expressing estrus prior to FTAI among cows with greater DPP. Across protocols, body condition score (BCS) affected (P = 0.05) estrus expression, with greater proportion of cows expressing estrus prior to FTAI at greater BCS. Sex-sorted semen resulted in reduced (P < 0.0001) pregnancy rates to FTAI. Irrespective of semen type, greater (P = 0.001) pregnancy rates to FTAI were obtained among cows treated with 7 & 7 Synch (conventional semen: 72% [280/389]; sex-sorted semen: 52% [199/380]) compared with the 7-day CO-Synch + CIDR (conventional semen: 60% [231/383]; sex-sorted semen: 44% [171/386]). In summary, 7 & 7 Synch resulted in an increased proportion of cows expressing estrus prior to FTAI and an increased pregnancy rate to FTAI with conventional and sexed semen. With these results and ease of application, 7 & 7 Synch offers potential as a platform to improve success with fixed-time AI in beef cows.

8 EFFECT OF SEMEN TYPES (SEXED v. NONSEXED) ON CONCEPTION RATES OF GIROLANDO HEIFERS INSEMINATED IN FIXED-TIME AI

2010 ◽  
Vol 22 (1) ◽  
pp. 162
Author(s):  
J. Almeida ◽  
O. A. Resende ◽  
D. L. Silveira
Keyword(s):  
Body Condition Score ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Sao Paulo ◽  
São Paulo ◽  
Device Removal ◽  
Conception Rates ◽  
Sexed Semen ◽  
Condition Score ◽  
Intravaginal Device

With the goal of optimizing protocols, fixed-time artificial insemination (FTAI) was performed under field conditions in a study to evaluate conception rates in Girolando (5/8) heifers (18 to 24 months of age) treated with estradiol benzoate (BE) to induce ovulation. Forty heifers were allocated to 2 groups with 20 animals each: GI-sexed semen (2 million spermatozoa/dose) and GII-nonsexed semen (20 million spermatozoa/dose), with body condition score (BCS) of 3.0 ± 0.14 (scale of 1 to 5), middleweight of 335 ± 38 kg, so that it was made for reutilization of progesterone device. On Day 0 (morning), the animals received 2.0 mg of BE (RIC-BE®,Tecnopec, São Paulo, Brazil), 0.075 mg of D-cloprostenol (Prolise®, ARSA S.R.L., Buenos Aires, Argentina), and an intravaginal device of 1 g of progesterone (Primer®, Tecnopec). On Day 8 (morning) the device was removed and 0.075 mg of D-cloprostenol was managed in the GI animals, then these animals received 1.0 mg of BE 24 h after device removal. The insemination was in the late afternoon of Day 10 with a 6-hour delay (4 to 6 pm). The GII animals received Primer previously used for 8 days (being used in the GI animals under the same protocol). After pregnancy diagnosis at 60 days, a third group was created (GIII) using the not-pregnant animals of GI and GII. In GIII, Primer from third use [disinfected in solution Kilol®-L 1:250 (Quinabra, São Paulo, Brazil) and rinsed with water, dried, and packed in plastic sacks and kept for 60 days] was used following the GI protocol with sexed semen. There were no significant differences (P > 0.05) in the conception rates of 40, 58, and 65% among groups GI (8/20), GII (11/20), and GIII (13/20). These results indicate very good conception rates for heifers, contrary to recommendations of commercial companies of sexed semen that alert for the conception rate for mated animals to be lower when using FTAI and mating protocols in mass, compared with that of AI after estrus observation.

178 USE OF A NEW INTRAVAGINAL DEVICE TO RELEASE PROGESTERONE IN FIXED-TIME EMBRYO TRANSFER EMBRYO RECIPIENTS

2010 ◽  
Vol 22 (1) ◽  
pp. 247
Author(s):  
J. R. V. Pimentel ◽  
P. H. P. Miguez ◽  
A. Kehrle ◽  
E. H. Madureira ◽  
F. A. Braga ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Body Condition Score ◽  
Block Design ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Sao Paulo ◽  
P Value ◽  
São Paulo ◽  
Condition Score ◽  
Intravaginal Device

Progestagen-releasing devices are commonly used for fixed-time artificial insemination and fixed-time embryo transfer (FTET). The aim of this study was to evaluate the efficacy of a new progesterone-releasing intravaginal device made of poly(3-hydroxy)butyrate-valerate copolymer (PHB-V) and poly-ϵ-caprolactone (PCL; Progestar®, Innovare, São Paulo, Brazil) to synchronize crossbredcows and heifers for FTET by determining ovulation, conception, and pregnancy rates. A total of 205 recipients ranging in age from 2 to 8 years (heifers, n = 77; non-suckled cows, n = 69; suckled cows, n = 59) were used on 3 different farms during February, March, and April 2008. The experimental design was a generalized block design (cyclicity, body condition score, postpartum interval, and animal category, i.e. heifers, suckled, or non-suckled cows), with 2 different synchronization treatments for FTET (Progestar® v. Crestar®). Cows were assigned to either Crestar® (norgestomet ear implants; Intervet Schering-Plough, Kenilworth, NJ, USA; n = 103) or Progestar® (PHB-V; n = 102) treatments. All groups were treated with 2 mg of estradiol benzoate i.m. (Innovare) and received the intravaginal or auricular device according to their group (Day 0). Together with P4 device withdrawal (Day 8), all animals received 400 IU of eCG i.m. (Novormon®, Schering-Plough) and 500 μg i.m. of PGF2α, (Sincrocio®, Ouro Fino, Brasil). On Day 9, all cows were treated with 1 mg of estradiol benzoate (Innovare) and the innovulation was performed on Day 17. Embryos were maintained at 37°C during the innovulation period. The percentage of usable recipients (AR) based on the presence of a functional CL on the day of embryo transfer, conception rate (numbers of pregnant recipients of the total number transferred; CR), and pregnancy rate (numbers of pregnant recipients of the total number synchronized; PR) were determined by ultrasonography 23 days after embryo transfer. Data were submitted to ANOVA (PROC GLM, SAS Institute Inc., Cary, NC, USA) and significant differences were considered to have a P-value of <0.05. None of the interactions were significant and there was no effect of treatment on AR (72.8% v. 83.3%), CR (47.9% v. 42.7%), and PR (34.7% v. 35.0%) for Progestar® v. Crestar® groups, respectively. This experiment showed that Progestar® was as efficacious as Crestar® to synchronize crossbred cows and heifers for FTET. FAPESP-Fundação de Amparo à Pesquisa do Estado de São Paulo and CNPq-Conselho Nacional de Desenvolvimento Científico e Tecnológico.

7 INFLUENCE OF ESTRUS EXPRESSION AND TREATMENT WITH GnRH ON PREGNANCY RATES IN BEEF CATTLE SYNCHRONIZED WITH PROGESTERONE DEVICES AND ESTRADIOL AND INSEMINATED AT A FIXED-TIME

2017 ◽  
Vol 29 (1) ◽  
pp. 111 ◽  
Author(s):  
G. A. Bó ◽  
A. Cedeño ◽  
A. Tribulo ◽  
S. Andrada ◽  
R. Tribulo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Beef Cattle ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Device Removal ◽  
Oestradiol Benzoate ◽  
Condition Score ◽  
To Receive

We have previously shown that expression of oestrus significantly influences the time of ovulation and pregnancy rates to timed-AI (P/TAI) in beef cattle synchronized with progesterone devices and oestradiol (Bó et al. 2016 Theriogenology 86, 388–396). Furthermore, delaying TAI from 48 h to 54–58 h after device removal improved P/TAI of those animals not showing oestrus by 48 h. The objective of the present study was to determine whether the administration of GnRH to those animals not showing oestrus by 48 h after device removal had an impact on P/TAI. Non-lactating and suckled beef cows and heifers (Bonsmara, Brangus, and Braford; n = 868), with a corpus luteum (CL) or a follicle ≥8 mm in diameter detected by ultrasonography (Mindray DP 30 Vet, 7.5 MHz, China) and body condition score 2 to 4 (1 to 5 scale) were synchronized in 3 replicates. On Day 0, animals received a progesterone device (DIB 0.5 g, Zoetis, Argentina) and 2 mg of oestradiol benzoate (Von Franken, Argentina). On Day 8, DIB were removed and cows received 0.150 mg of D+cloprostenol (Río de Janeiro, Argentina) plus 0.5 mg oestradiol cypionate (Cipiosyn, Zoetis). In addition, all cows were tail-painted on the sacrococcygeal area (CeloTest, Biotay, Argentina) at DIB removal and were observed to determine the expression of oestrus, according to the percentage of paint loss (PL) 48 h later. The animals that showed oestrus (PL > 30%) were recorded and TAI at that time while those with PL ≤ 30% (not in oestrus) were randomly allocated to receive 100 μg of gonadorelin (GnRH; Gonasyn, Zoetis) or no treatment and TAI between 54 to 58 h after DIB removal. Pregnancy was diagnosed by ultrasonography at 45 days after TAI, and data were analysed by logistic regression. There were no significant differences among replicates, inseminators, semen source or animal class (dry cows, suckled cows or heifers; P > 0.11). However, animals showing oestrus by 48 h after DIB removal had higher P/TAI (371/666; 55.7; P < 0.04) than those that did not show oestrus (96/202; 47.5%). Within animals not showing oestrus at 48 h, those that were in oestrus by the TAI at 54 to 58 h had higher P/TAI (71/124, 57.3%; P < 0.01) than those that did not show oestrus within that period (27/78; 34.6%). In addition, P/TAI was higher (P < 0.01) in animals that received GnRH (66/113; 58.4%) than in those that did not receive GnRH (30/89; 33.7%). In conclusion, the expression of oestrus significantly affected P/TAI in beef cattle synchronized with progesterone devices and oestradiol. Furthermore, treatment of animals not showing oestrus by 48 h after DIB removal with GnRH resulted in improved P/TAI performed 6 to 10 h later.

12 OVARIAN STRUCTURES, ESTRUS EXPRESSION, AND PREGNANCY RATE IN BEEF HEIFERS USING ESTRADIOL CYPIONATE OR GnRH AS OVULATION INDUCTORS IN TIMED AI PROTOCOL

2017 ◽  
Vol 29 (1) ◽  
pp. 113 ◽  
Author(s):  
E. Pradebon da Silva ◽  
A. B. Machado ◽  
L. S. Gambin ◽  
A. V. Gonsioroski ◽  
M. da Silva ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Body Condition Score ◽  
Device Removal ◽  
Treatment Groups ◽  
Follicle Diameter ◽  
Ovulatory Follicle ◽  
Condition Score ◽  
In The Beginning ◽  
Angus Heifers ◽  
Intravaginal Device

The aim of this study was to evaluate the effect of presence of corpus luteum (CL) at the onset of timed AI (TAI) protocol, size of ovulatory follicle and oestrus expression on pregnancy rate using E2 cypionate (EC) or GnRH as ovulation inductor in Angus heifers. On day 0, heifers [n = 414; 317 ± 23 kg; 3.08 ± 0.21 body condition score (1 to 5 scale) and 22–24 months of age] received a 1-g progesterone intravaginal device (Primer®, Agener União, Brazil) and 2 mg of oestradiol benzoate, IM, (RIC-BE®, Agener União, Brazil). On day 8, the device was removed, were administered 500 μg of sodium cloprostenol, IM, (Estron®, Agener União, Brazil) and heifers were divided in 2 groups: EC [n = 213; 0.5mg EC, IM, (SincroCP®, Ouro Fino, Brazil) on day 8] and GnRH [n = 201; 25 μg of Licerelin, IM, (GestranPlus®, Agener União, Brazil) at TAI] TAI was performed 50 h after device removal. Heifers were tail painted (Tell Tail®, GEA, New Zealand) to control oestrus expression from device removal to TAI. Heifers were scanned (7.5-MHz linear transducer MediSono® P3V, USA) to determine presence of CL (Day 0), ovulatory follicle diameter (OFD; Day 10) and ovulation (Day 11). Pregnancy was diagnosed 30 days after TAI. Oestrus expression was confirmed when marking ink was removed on day 10. Data were analysed using logistic regression and ANOVA. Oestrus expression was higher (P < 0.05) in EC (93.90%, 200/213) compared to GnRH group (67.66%, 136/201). The OFD differed (P < 0.05) according to presence of CL on Day 0 (10.3 mm) or not (9.6 mm), but was similar in treatment groups. Ovulation rate did not differ in EC (85%, 17/20) and GnRH (95%, 19/20) groups. Pregnancy rates were similar (P > 0.05) between EC (52.58%, 112/213) and GnRH (59.20%, 119/201) groups; however, in heifers that expressed oestrus, rates were higher (P < 0.05) (EC = 56%, 112/200; GnRH = 71.3%, 97/136) than in those did not show (EC = 0%, 0/13; GnRH = 33.8%, 22/65). Presence of CL at onset of TAI protocol was associated with higher pregnancy (P < 0.05) in GnRH group (68%, 68/100) compared with EC (54.46%, 61/112) group, but in heifers without CL, pregnancy were similar for GnRH (50.5%, 51/101) and EC (50.5%, 51/101) groups. Heifers were also classified in 3 groups according OFD: small (≤9.5 mm), medium (9.6–11.5 mm), and large (≥11.6 mm) to verify its effect on oestrus expression and pregnancy. Medium and large OFD were implicated in higher (P < 0.05) oestrus expression [(EC = 100%, 51/51; 96.97%, 32/33) and (GnRH = 83.02%, 44/53; 97.44%, 38/39)] than small OFD [(EC = 85%, 51/60) and (GnRH = 23.8%, 15/63)]. Pregnancy was lower (P < 0.05) in small OFD groups (EC = 28.3%, 17/60; GnRH = 25.4%, 16/63). In medium and large OFD, pregnancy was similar in EC (72.55%, 37/51; 54.55%, 18/33) groups, but differed (P < 0.05) between GnRH large (82.05%, 32/39) and medium (62.26%, 33/53). Higher pregnancy was achieved in heifers with CL in the beginning of TAI protocol treated with GnRH. Size of ovulatory follicle was associated with higher oestrus behaviour and pregnancy rate in EC and GnRH treatments.

scholarly journals The use of insulin to improve fertility of timed-inseminated postpartum suckled beef cows

2010 ◽  
Vol 45 (10) ◽  
pp. 1219-1221 ◽  
Author(s):  
Augusto Schneider ◽  
Luiz Francisco Machado Pfeifer ◽  
Eduardo Schmitt ◽  
Ivan Bianchi ◽  
Marcelo Brandi Vieira ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Body Condition ◽  
Chorionic Gonadotropin ◽  
Artificial Insemination ◽  
Body Condition Score ◽  
Insulin Injection ◽  
Fixed Time ◽  
Beef Cows ◽  
Condition Score ◽  
Equine Chorionic Gonadotropin

The objective of this work was to evaluate the effect of insulin alone or in association with equine chorionic gonadotropin (eCG) on the fertility of postpartum beef cows subjected to synchronization. A total of 340 cows was subjected to fixed time artificial insemination. In the trial 1, the cows were subjected to temporary weaning (TW), while in the trial 2 the same protocol was tested without TW. The addition of an insulin injection to a progesterone/eCG-based protocol without TW increased the pregnancy rate of beef cows with body condition score (BCS) equal to or lower than 2.5. Insulin had no effect on cows submitted to TW or with BCS equal to or higher than 3.0.

scholarly journals Development of fixed-time artificial insemination protocols for locally adapted Curraleiro Pé-Duro cows

2016 ◽  
Vol 68 (5) ◽  
pp. 1159-1167 ◽  
Author(s):  
R.D. Tortorella ◽  
M.R. Modesto ◽  
J.P. Neves ◽  
A.F. Ramos
Keyword(s):  
Body Condition Score ◽  
Hormonal Treatment ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Device Removal ◽  
Condition Score ◽  
Equine Chorionic Gonadotropin ◽  
Hot Environments ◽  
To Receive ◽  
Intravaginal Device

ABSTRACT Two experiments were conducted aiming to evaluate the effects of two ovulatory inducers (Exp.1) and equine chorionic gonadotropin (eCG; Exp.2) on follicular and luteal dynamics in a fixed-time AI (FTAI) protocol in locally adapted Curraleiro Pé-Duro cows. In Exp. 1 multiparous cows (n=12) received an intravaginal device containing 1g of progesterone (P4) for 8 days and 2mg of estradiol benzoate (EB) intramuscularly (IM) at device insertion (Day 0). At device removal (Day 8) 0.150mg of Sodium D-Cloprostenol was administered IM and the cows were randomly assigned to receive 1mg of EB (EB8) or 1mg of estradiol cypionate (EC8) IM, or to not receive any ovulatory inducer (Control). All the animals participated in all treatments (crossover). The interval from P4 removal to ovulation was shorter and less variable in the EB8 treatment group (P≤0.05). In Exp. 2 (crossover), multiparous cows (n=12) received the same hormonal treatment as the EB8 group in Exp.1. At device removal (Day 8) cows were randomly assigned to receive 300UI of eCG IM or to not receive eCG (Control). No difference was ascertained on follicular and luteal parameters in Exp. 2 (P>0.05). We concluded that EB can be used as the ovulatory inducer (Exp. 1) in a FTAI protocol in Curraleiro Pé-Duro cows. However, eCG (Exp. 2) was not able to stimulate follicular and luteal development. This result is probably due to the adaptive capacity of Curraleiro Pé-Duro cows that maintained a satisfactory body condition score even in dry and hot environments.

scholarly journals 9THE USE OF ECG TO INCREASE PREGNANCY RATES IN POSTPARTUM BEEF COWS FOLLOWING TREATMENT WITH PROGESTERONE VAGINAL DEVICES AND ESTRADIOL BENZOATE AND FIXED-TIME AI

2004 ◽  
Vol 16 (2) ◽  
pp. 127 ◽  
Author(s):  
G.A Bo ◽  
L. Cutaia ◽  
P. Chesta ◽  
D. Moreno
Keyword(s):  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Control Group ◽  
Treatment Groups ◽  
Condition Score ◽  
N 93 ◽  
Rectal Palpation

Treatments with progesterone (P4) releasing devices and estradiol benzoate (EB) have been extensively used in fixed-time AI (FTAI) programs in beef cattle. However, pregnancy rates in postpartum cows kept on pasture often have been lower than expected because of poor body condition score (BCS) and a high incidence of anestrous. A recent study (Cutaia L et al., 2003 Theriogenology 59, 216) suggested that the addition of eCG to a P4/EB FTAI program may improve pregnancy rates in cows with fair to poor BCS, but results were not conclusive. Therefore, this experiment was designed to further investigate the effect of eCG treatment on pregnancy rates in postpartum beef cows in those conditions. The experiment was performed at 2 locations with lactating Angus cows (n=93), 60 to 90d postpartum with a BCS 1.9 (1 to 5 scale; Location 1), and crossbred Zebu cows (n=290), 60 to 90d postpartum with a BCS 2.0 (Location 2). In each Location, cows were randomly allocated to 1 of the following treatment groups: Control, eCG Day6, or eCG Day8. All cows received a P4 intravaginal device (DIB, Syntex, Argentina) and 2mg EB i.m. (Syntex) on Day0, 500mg cloprostenol (Estroplan, Syntex) at the time of DIB removal (Day8), 1mg EB i.m. on Day9 and FTAI 52 to 56h after DIB removal. Cows in the Control group received no further treatment, whereas cows in the eCG-treated groups received 400 IU eCG (Novormon 5000, Syntex) on Day6 or Day8. Cows were examined on Day0 by rectal palpation (Location 1) or by ultrasonography (US; Location 2) and were classified as those with a CL or without a CL, with either large (&gt;8mm) or small (&lt;8mm)small follicles. Pregnancy was determined by US 45d after FTAI. Data were analyzed by logistic regression and the effects of location, treatment, ovarian status, AI technician and semen were considered in the model. There was no effect of location (P=0.3), AI technician (P=0.2) or semen (P=0.8) on pregnancy rates. However, there was an effect of treatment (P=0.02), attributed to higher pregnancy rates in the eCG Groups than in the Control Group (Table). Furthermore, cows with a CL or without a CL but with large follicles on Day 0 had higher pregnancy rates than those with small follicles (P=0.04). It was concluded that the use of eCG in a P4/EB FTAI program improved pregnancy rates in postpartum beef cows that were in fair topoor BCS.

12 THE EFFECT OF PROGESTERONE CONTENT IN A VAGINAL INSERT ON PREGNANCY RATES IN BEEF AND DAIRY CATTLE INSEMINATED AT FIXED TIME

2006 ◽  
Vol 18 (2) ◽  
pp. 114
Author(s):  
L. Cutaia ◽  
M. Aviles ◽  
F. Feresin ◽  
A. Franzoni ◽  
L. Peres ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Holstein Cows ◽  
Chi Square ◽  
Condition Score ◽  
Chi Square Test

Three experiments were conducted to compare pregnancy rates in cows and heifers treated with intravaginal progesterone (P4)-releasing devices impregnated with either 0.5 or 1.0 g of P4 and inseminated at a fixed time (FTAI). In Experiment 1, 102 postpartum beef cows (Hereford and Angus crossbred with Tuli, 60 to 90 d postpartum) with a body condition score (BCS) of 2.5 to 3.0 (1 to 5 scale) were used. On Day 0, all cows received 2 mg of estradiol benzoate (EB; Syntex, Argentina) i.m. and were randomly assigned to receive an intravaginal progesterone-releasing device with 0.5 g of P4 (DIB 0.5 g; Syntex) or 1.0 g of P4 (DIB 1.0 g; Syntex). On Day 7, DIB devices were removed and all cows received 150 µg D(+)cloprostenol (Ciclase; Syntex) i.m. On Day 8, all cows received 1 mg EB and were FTAI 52 to 56 h after DIB removal. In Experiment 2, 93 Holstein cows that were 90 to 110 days in milk (DIM), producing on average 5000 kg of milk per lactation and with a BCS of 2.5 to 3.0 received the same treatments as those in Experiment 1. In Experiment 3, 100 Holstein heifers, 20 to 22 months old, with a BCS of 2.5 to 3.0, also received the same treatments as those in Experiment 1. Pregnancy rates in all experiments were determined by ultrasonography 35 days after FTAI and compared by chi-square test. No differences in pregnancy rates were detected between lactating beef cows, dairy cows, or dairy heifers treated with DIB devices impregnated with 0.5 or 1.0 g of P4 (Table 1). It was concluded that vaginal P4 releasing devices impregnated with 0.5 g or 1.0 g of P4 results in comparable pregnancy rates in FTAI protocols in beef and dairy cattle. Table 1. Pregnancy rates in postpartum beef cows, Holstein cows, and Holstein heifers treated with DIB devices impregnated with 0.5 or 1.0 g of P4 and subjected to FTAI

362 EFFECT OF TIME OF REMOVAL OF A PROGESTERONE RELEASING DEVICE AND GnRH TREATMENT ON THE INTERVAL TO AND DISTRIBUTION OF OVULATIONS IN SUPERSTIMULATED BEEF COWS

2006 ◽  
Vol 18 (2) ◽  
pp. 288 ◽  
Author(s):  
P. Chesta ◽  
D. Maraña ◽  
L. Peres ◽  
G. A. Bo
Keyword(s):  
Body Condition Score ◽  
Animal Health ◽  
Fixed Time ◽  
Beef Cows ◽  
Unequal Variances ◽  
Treatment Groups ◽  
Condition Score ◽  
Red Angus ◽  
To Receive ◽  
Mean Time

An experiment was designed to evaluate the effect of the time of removal of an intravaginal progesterone (P4) releasing device and GnRH treatment on the interval to and the distribution of ovulations in beef cows superstimulated with Folltropin-V (Bioniche Animal Health, Belleville, Ontario, Canada). Red Angus donors (22 cows and 12 heifers) with a body condition score between 2.5 to 3.5 out of 5 were blocked by parity and randomly assigned to one of four treatment groups in a 2 × 2 factorial design. On Day 0, all donors received an i.m. DIB vaginal device (Syntex, Argentina) plus 2.5 mg estradiol-17β and 50 mg P4 (Laboritorio Rio de Janeiro, Argentina). Superstimulatory treatments were initiated on Day 4, with a total dose of 320 mg (cows) or 200 mg (heifers) NIH-FSH-P1 (Folltropin-V; Bioniche Animal Health, Inc., Belleville, Ontario, Canada) in twice daily i.m. injections over 4 days. All cows received PGF treatment (150 μD(+)cloprostenol: Ciclase; Syntex) in the morning and afternoon of Day 6 and were randomly divided to have DIB devices removed at the time of the second PGF treatment (Day 6.5) or 12 h later (Day 7). On Day 8, donors were further subdivided to receive GnRH (0.050 mg Lecirelina, Gonasyn; Syntex) or no further treatment, and all cows were fixed-time AI either 60 and 72 h after the first PGF injection (0 h). All cows and heifers were examined by ultrasonography every 8 h for a period of 120 h commencing at the time of DIB removal, to determine the time and distribution of ovulations. For each cow, mean time of ovulation was used for the statistical analysis. The distributions of ovulations were compared among groups by Levene's test, and then by ANOVA (equal variances) or Friedman two-way non-parametric ANOVA (unequal variances). No significant differences were detected between cows and heifers (P > 0.13) for the parameters evaluated, and data were combined. There was no effect (P > 0.22) of treatment on the number of ovulations (GnRH: 12.6 ± 1.6 vs. no GnRH: 15.1 ± 1.1 and Day 6.5: 13.7 ± 1.3 vs. Day 7: 14.3 ± 1.5), or numbers of transferable embryos (GnRH: 5.1 ± 1.1 vs. no GnRH: 3.1 ± 0.8 and Day 6.5: 3.5 ± 0.8 vs. Day 7: 4.81 ± 0.1). However, there was a significant effect of GnRH treatment and a GnRH-by-time-of-DIB-removal interaction on the distribution of ovulations (P < 0.05; Table 1). The administration of GnRH in a superstimulatory protocol using P4 releasing devices results in earlier and more synchronous ovulations than when GnRH is not used. Table 1. Distribution of ovulations (hours after the first PGF) in superstimulated Red Angus donors treated with progesterone-releasing devices (DIB) for 6.5 or 7 days with and without GnRH treatment on Day 8

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