9 Fixed timed artificial insemination during different seasons in Argentina (2016–2019)

2021 ◽  
Vol 33 (2) ◽  
pp. 112
Author(s):  
A. S. Bandeo ◽  
J. A. Berdugo ◽  
G. A. Crudeli ◽  
P. Maldonado-Vargas ◽  
J. L. Konrad
Keyword(s):  
Prostaglandin F2α ◽  
Fixed Time ◽  
Dominant Follicle ◽  
Breeding Performance ◽  
Different Seasons ◽  
Gonadotrophin Releasing Hormone ◽  
Timed Artificial Insemination ◽  
Native Pastures ◽  
Intravaginal Device ◽  
Positive Effect

The objective of this work was to evaluate pregnancy rates in buffaloes subjected to fixed-time AI (FTAI) during the year in Argentina. The data analysed was collected between 2016 to 2019 in a farm located in Paso Florentin City (27°20′33″ latitude and 58°08′27″ longitude) in Corrientes, Argentina. The animals were grazing native pastures (Andropogon lateralis, Paspalum almum). Ten fixed-time AI (FTAI) sessions were performed, 6 within the favourable season (BS, March–June) and 4 in the outbreeding season (OBS; September–December). Murrah and Mediterranean breed (n=141) buffaloes were used. All animals were healthy, without anatomical alterations and with normal reproductive tracts. Heifers (H), adult females with calf (AFC), and dry buffaloes (DB) were used. The average (±s.d.) weight of the animals were 459.0±37.5kg, 581.3±53.6kg, and 583.3±53.1kg, respectively. The presence of corpus luteum (CL) or a dominant follicle (≥8mm) at the beginning of the protocol was recorded. BS ovulation induction: Ovsynch (n=182); Day 0 gonadotrophin-releasing hormone (GnRH; 100μg, busereline acetate), Day 7 prostaglandin F2α (150μg, cloprostenol), Day 9 GnRH and FTAI 16h after the last GnRH injection. For the OBS (n=85): Day 0 intravaginal device (700mg of P4) + oestradiol benzoate (0.2g), Day 8 removal of the device + prostaglandin F2α + oestradiol cypionate (0.1g) + eCG (400IU) and Day 10 FTAI (52–56h) after device removal. Semen from 5 bulls of proven fertility was used, and the same technician performed all the inseminations. A specifically designed format to record the data were used and the average±s.d. of the physiological and the meteorological parameters were calculated. Pregnancy was detected 40 days after FTAI using ultrasonography. Comparison within variables were performed using ANOVA and Tukey test, with InfoStat-Statistical Software. A total of 267 inseminations were performed, and the overall pregnancy rate (PR) was 37.45% (100/267). Comparing BS with OBS, PR were 40.7% (74/182) and 30.6% (26/85) (P<0.005). Heifers had a higher PR (51.5%) than suckled buffaloes (38.8%) and dry buffaloes (20%) during the BS (P<0.05). In the OBS, there were no differences among categories on PR for [36.36 (4/11) H, 28.57 (12/42) AFC, 19.51 (8/41) DB; P>0.05]. The presence of a CL at the beginning of the FTAI protocol had a positive effect on PR during the year in all categories [31.79% (55/173) H, 40.42 (38/94) AFC, 21.51 (17/79) DB vs. 25.45% (28/110) H, 29.68 (19/64) AFC, 19.56 (9/46) DB; P<0.05]. Season had a significant effect over PR, but rain, temperature, daylight, and humidity did not differ during the year. These results show the feasibility of FTAI in water buffalo, confirm that it is possible to maintain the PR during the year, and demonstrate successful performance of protocol induction in cyclic females during the year. More research is needed to improve PR in buffaloes in Argentina, to explain the low results in suckled and dry adult buffaloes, and to analyse the effect of meteorological conditions over the breeding performance of the animals.

109 Pre-synchronization and reutilization of progesterone devices during a 6-day CO-Synch protocol for fixed-time artificial insemination in beef heifers

2021 ◽  
Vol 33 (2) ◽  
pp. 161
Author(s):  
E. R. Canadas ◽  
B. J. Duran ◽  
G. Machado ◽  
A. Nall ◽  
S. E. Battista ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Mixed Models ◽  
Generalized Linear Mixed Models ◽  
Fixed Time ◽  
P Value ◽  
Beef Heifers ◽  
Follicle Diameter ◽  
Follicle Size ◽  
Gonadotrophin Releasing Hormone ◽  
Intravaginal Device

Ovulatory response to the initial gonadotrophin-releasing hormone (GnRH) of the CO-Synch protocol is affected by circulating progesterone (P4) and follicle size. In addition, heifers that ovulate to the initial GnRH treatment have greater fertility after AI. Thus, this study determined the effect of (1) presynchronization (Presynch) before a 6-day CO-Synch protocol and (2) circulating [RCE1] (P4) on ovulatory response, oestrus expression, and pregnancies per AI (P/AI) in beef heifers. Yearling beef heifers (n=233) at three locations were randomly assigned in a 2×2 factorial design to the following treatments: (1) Presynch+6-day CO-Synch with a new P4 device; (2) Presynch+6-day CO-Synch with a once-used P4 device; (3) 6-day CO-Synch with a new P4 device; and (4) 6-day CO-Synch with a once-used P4 device. Presynch consisted of insertion of a new P4 intravaginal device (1.38g of P4) on Day −17 and removal of P4 device on Day −11 concurrently with 500µg of cloprostenol sodium (PGF). On Day −9, all heifers received either a new (New) or once-used (Used) CIDR and 100µg of gonadorelin acetate (GnRH). Six days later (Day −3), CIDRs were removed, 1000µg of PGF was administered and an oestrous detection patch applied (Estrotect). At 72h after CIDR removal, AI was performed concurrently with administration of 100µg of GnRH. Pregnancy was determined by transrectal ultrasonography 31 days after AI. A subset of heifers (n=155) was examined on Day −9 and Day −3 by ultrasonography to determine ovulation to Day −9 GnRH. Data were analysed using generalized linear mixed models (SAS 9.4; SAS Institute Inc.). Presynch heifers had larger follicle diameter on Day −9 (12.7±0.3 vs. 10.1±0.3 mm; P<0.001), greater ovulatory response to Day −9 GnRH (82.5%; 66/80 vs. 56%; 42/75; P<0.001), greater expression of oestrus (90.6%; 106/117 vs. 78.4%; 91/116; P<0.02), and earlier oestrus (49.8±1 vs. 53.1±1 h; P<0.01) compared with controls. There was a treatment×CIDR interaction on oestrous expression, such that a lesser (P<0.05) percentage of control heifers with new CIDR expressed oestrus compared with all other groups (Table 1). Heifers with a used CIDR during the 6-day CO-Synch tended (P=0.08) to have greater P/AI (52.1%; 61/117) than those with a new CIDR (40.5%; 47/116). In conclusion, presynchronization before initiation of a 6-day CO-Synch increased follicle diameter, enhanced ovulatory response and oestrous expression, but did not affect fertility. The earlier onset of oestrus in presynchronized heifers suggests that the timing of AI may need to be modified. Table 1. Oestrous expression and pregnancy per AI (P/AI) in beef heifers with or without presynchronization and treated with a new or used CIDR during a 6-day CO-Synch Treatment CIDR Oestrus (%; n/n) Time of oestrus (h) P/AI (%; n/n) Control New 67.8a (40/59) 53.7±1.5a 33.9 (20/59) Used 89.5b (51/57) 52.7±1.6a 50.9 (29/57) Presynch New 94.7b (54/57) 50.9±1.4b 47.4 (27/57) Used 86.7b (52/60) 48.7±1.3b 53.3 (32/60) P-value Treatment 0.03 0.01 0.21 CIDR 0.62 0.19 0.08 Interaction 0.003 0.75 0.38 a,bValues with different superscripts differ (P<0.05).

scholarly journals PSXIII-11 Altering length of the presynchronization period in a long-term progestin-based estrus synchronization protocol for timed artificial insemination of beef heifers

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 375-376
Author(s):  
Emma R Knickmeyer ◽  
Jordan M Thomas ◽  
James William C Locke ◽  
Rachael C Bonacker ◽  
Lauren Ciernia ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Reproductive Tract ◽  
Prostaglandin F2α ◽  
Estrus Synchronization ◽  
Dominant Follicle ◽  
Estrus Detection ◽  
Timed Artificial Insemination ◽  
Split Time ◽  
Synchronization Protocol

Abstract An experiment was designed to evaluate the effect of extending the presynchronization period in a progestin-based estrus synchronization protocol. Heifers were assigned to an 18 d or 14 d CIDR® treatment (1.38 g progesterone), with prostaglandin F2α (PG; 250 mg im) administered 16 d after CIDR® removal (Day 34). Heifers at two locations (location one, n = 193; location two, n = 649) were assigned to treatment based on reproductive tract score (RTS; Scale 1–5) and weight. Estrus detection aids (Estrotect®) were applied at PG and split-time artificial insemination (STAI) was performed based on estrus expression at 66 h. Heifers that expressed estrus at 66 h were inseminated and heifers that did not express estrus were inseminated at 90 h. Only heifers that failed to express estrus by 90 h received gonadotropin-releasing hormone (GnRH; 100 µg im) at AI. At location one, blood samples were collected at PG and AI (66 h or 90 h) from all heifers to determine E2 concentrations, and transrectal ovarian ultrasound was performed to detail ovarian structures on a subset of heifers (n = 73) at both time points. The proportion of heifers expressing estrus by 66 h (60%) or in total by 90 h (84%) after PG did not differ between treatments. Pregnancy rate to STAI did not differ between treatments (P = 0.3; 52%, 14 d CIDR®-PG; 50%, 18 d CIDR®-PG), or at the end of the 60 d breeding season (P = 0.2). There were no differences between treatments in mean diameter of the dominant follicle at PG (P = 0.6) or STAI (P = 0.3), nor were any differences observed between treatments in E2 concentrations at PG (P = 0.8) or STAI (P = 0.6). These data suggest that CIDR® treatment can be extended from 14 to 18 d, providing flexibility in scheduling without compromising reproductive outcomes.

77 Occurrence of early regression of corpora lutea in Dorper ewes subjected to a conventional superovulatory regimen

2021 ◽  
Vol 33 (2) ◽  
pp. 146
Author(s):  
M. S. Rocha ◽  
A. L. R. S. Maia ◽  
P. S. C. Rangel ◽  
L. M. Tavares ◽  
M. E. F. Oliveira ◽  
...  
Keyword(s):  
Body Condition Score ◽  
Genetic Material ◽  
Corpora Lutea ◽  
Multiple Ovulation ◽  
Chi Squared ◽  
Condition Score ◽  
Different Seasons ◽  
Gonadotrophin Releasing Hormone ◽  
Intravaginal Device ◽  
Functional Alteration

The early regression of corpora lutea (ERCL) is a functional alteration that occurs more often in animals subjected to multiple ovulation followed by embryo transfer (MOET) technique. Although it is mainly reported in goats, sheep are also susceptible to this disorder. The ERCL may compromise the quality and viability of embryos, and even embryonic recovery rate. Thus, the non-diffusion of the animal genetic material on a commercial scale increases costs, decreasing efficiency. This study aimed to assess the occurrence of ERCL in embryo donor ewes subjected to the MOET programs in different seasons. The research was carried out in a commercial herd in São Luís do Paraitinga city (23°22′S and 45°26′W), Brazil, over 4 years (2017–2020). Forty-four Dorper multiparous ewes aged between 3 and 9 years old and with body condition score (BCS) between 2 and 4.5 (1 to 5 scale) were used. Each ewe was used at least once for MOET and a maximum of 5 times, totalling 104 procedures. Regardless of the day of the oestrous cycle or anovulatory period (Day 0), ewes received a conventional superovulatory protocol consisting of an intravaginal device treatment with 0.33mg of progesterone (CIDR®, Zoetis). On Day 7, the device was replaced with a new one and ewes administered i.m. 0.24mg of sodium cloprostenol (Sincrocio®, Ourofino). The superovulatory treatment [256mg of FSH (Folltropin®, Vetoquinol)] started on Day 12 and consisted of decreasing doses (20, 20, 15, 15, 10, 10, 5, and 5%) administered intramuscularly (IM) every 12h for 4 days plus 200IU of equine chorionic gonadotrophin (eCG, Novormon®, Zoetis) at device removal on Day 14 and 0.1mg of gonadotrophin-releasing hormone (Fertagyl®, MSD) IM 1 day later (Day 15). Laparoscopic AI was performed twice on Day 16 using cooled semen. Five days after AI, ovaries were assessed by laparoscopy to check the presence and viability of corpora lutea (CL). Ewes that had avascular CL (pinkish to whitish colour) were classified as ERCL and embryo collection was not performed. The occurrence of ERCL in each season and category of BCS was checked by either chi-squared or Fisher test. Logistic regression was performed according to the incidence of ERCL in each category of age. Values of P<0.05 were considered as significant. From 104 procedures, ERCL was identified in 26 cases, totalling 25% of occurrence. The proportion of occurrence did not differ (P>0.05) among seasons: breeding (10/43: 23%), transition (10/36, 28%), or anoestrous (6/25, 24%). There was no difference in ERCL incidence in ewes presenting different BCS categories: lower/thin (2 to 2.5: 3/12, 25%); average/good (3 to 3.5: 15/66, 22%) and higher/fat (4 to 4.5: 8/26, 31%). Indeed, there was no association (P>0.05) between ERCL and age. In conclusion, a relevant occurrence of ERCL was detected in superovulated embryo donor ewes but this incidence was not associated with season, age, or BCS of Dorper ewes. These data highlight the importance of pharmacological measures to control ERCL in MOET protocols for commercial sheep herds.

13 Pre-synchronization by Induction of a Dominant Follicle Using a Progesterone Device in a GnRH-Based-Ovulation Synchronization Protocol in Lactating Dairy Cows

2018 ◽  
Vol 30 (1) ◽  
pp. 146
Author(s):  
M. P. Bottino ◽  
L. A. C. L. DaSilva ◽  
L. M. S. Simoes ◽  
G. Santos ◽  
I. Y. H. Martinez ◽  
...  
Keyword(s):  
Sustained Release ◽  
Dairy Cows ◽  
Prostaglandin F2α ◽  
Follicular Development ◽  
Experimental Period ◽  
Ovulation Rate ◽  
Dominant Follicle ◽  
Lactating Dairy Cows ◽  
Intravaginal Device ◽  
Synchronization Protocol

The objective was to compare a pre-synchronization protocol by induction of a dominant follicle using a progesterone intravaginal device before an Ovsynch protocol (Presynch) with Double-Ovsynch in lactating dairy cows. Lactating Bos indicus × Bos taurus crossbred cows (n = 440) were randomly allocated to 1 of 2 treatments (all IM injections): (1) Double-Ov (n = 228): GnRH (Day –17), prostaglandin F2α (PGF2α) 7 days later (Day –10) and gonadotropin-releasing hormone (GnRH) 3 days later (Day –7) followed by an Ovsynch protocol 7 days later (GnRH on Day 0, PGF2α on Day 7, GnRH on Day 9); (2) Presynch (n = 212): insertion of a sustained release progesterone intravaginal device (Day –10), 10 days later (Day 0), an Ovsynch protocol was initiated with progesterone device withdrawal on Day 7. All cows were artificially inseminated 15 to 20 h after the second GnRH injection of the Ovsynch protocol and were pregnancy checked by ultrasonography 30 and 60 days later. On a subsample (n = 102), ultrasonography was performed on Days 0, 7, 9, and 24 of the experimental period. On another subsample (n = 42), blood samples for progesterone analysis were taken on Days 0, 7, and 24. There were no differences between pre-synchronization methods on synchronization parameters [presence of a follicle >12 mm on D0, Double-Ov 94.2% (49/52) and Presynch 92.0% (46/50); P = 0.66], follicular diameter on the 1st GnRH (Double-Ov 17.2 ± 0.7 mm and Presynch 18.6 ± 0.9 mm; P = 0.28), ovulation rate to the 1st GnRH [Double-Ov 86.3% (44/51) and Presynch 81.2% (39/48); P = 0.50], synchronization rate [Double-Ov 84.6% (44/52) and Presynch 86.0% (43/50); P = 0.84], follicular diameter on the 2nd GnRH (Double-Ov 17.5 ± 0.6 mm and Presynch 18.0 ± 0.5 mm; P = 0.48), ovulation rate to the 2nd GnRH [Double-Ov 90.9% (40/44) and Presynch 86.0% (37/43); P = 0.48] and CL diameter on Day 24 (Double-Ov 27.9 ± 0.7 mm and Presynch 29.4 ± 0.9 mm; P = 0.19). Corpus luteum presence on Day 0 was different (P = 0.03) between treatments [Double-Ov 57.7% (30/52) and Presynch 36.0% (18/50)]. Moreover, there was no difference (P = 0.85) between pregnancy rates on Day 30 [Double-Ov 39.0% (89/228) and Presynch 40.1% (85/212)] or Day 60 after AI [Double-Ov 34.8% (79/227) and Presynch 38.7% (82/212); P = 0.41] and gestational loss between 30 and 60 days after AI [Double-Ov 7.9% (7/88) and Presynch 3.5% (3/85); P = 0.13]. Proportion of cows with P4 <1 ng mL−1 on Day 0 was similar between treatments [Double-Ov 13.6% (3/22) v. Presynch 5.0% (1/20); P = 0.37]. Likewise, the proportion of cows with P4 >1 ng mL−1 on Day 7 [Double-Ov 77.3% (17/22) v. Presynch 95.0% (19/20); P = 0.14] and P4 concentration on Day 24 (Double-Ov 4.7 ± 0.6 v. P4-Ov 5.9 ± 0.9; P = 0.84) were similar between treatments. In conclusion, pre-synchronization by induction of follicular persistence using a sustained-release progesterone device before Ovsynch yielded similar results to the Double-Ovsynch protocol on follicular development and regression patterns and on the fertility of lactating dairy cows.

17 INFLUENCE OF DIFFERENT CONCENTRATIONS OF PROGESTERONE DURING FIXED-TIME ARTIFICIAL INSEMINATION PROTOCOLS ON OVULATION AND PREGNANCY RATES IN NELORE HEIFERS

2008 ◽  
Vol 20 (1) ◽  
pp. 89
Author(s):  
M. F. Pegorer ◽  
R. L. Ereno ◽  
C. M. Barros
Keyword(s):  
Artificial Insemination ◽  
Bos Indicus ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
High Concentration ◽  
Serum Progesterone ◽  
Significant Difference ◽  
Intravaginal Device

Previous reports indicate that a high concentration of serum progesterone (P4) decreases LH pulse frequency (Burke et al. 1996 Anim. Reprod. Sci. 45, 13–28) and, consequently, follicular growth. This may reduce the efficiency of fixed-time artificial insemination (FTAI) protocols that utilize P4 in Bos indicus heifers (Marques et al. 2005 Acta Sci. Vet.). The objective of the present work was to evaluate the influence of different P4 concentrations on the ovulation and pregnancy rates of zebu heifers subjected to hormonal protocols for FTAI. Four hormonal protocols with different P4 concentrations were used to induce synchronization of ovulation in Nelore (Bos indicus) heifers (n = 292). Before the beginning of the treatments, the animals were subjected to ovary evaluations by ultrasonography (Aloka SSD 500, 5-MHz probe; Aloka, Tokyo, Japan) twice in an interval of 10 days. Only heifers with a corpus luteum (CL) in at least one of the ultrasonographic evaluations were utilized. At a random stage of the estrous cycle, the selected heifers received an intravaginal progesterone-releasing device containing 0.558 g of P4 [Triu�, Biogenesis, Buenos Aires, Argentina; Treatment 1 (T1); n = 76], or 1 g of P4 [Cronipress�, Biogenesis; Treatment 2 (T2); n = 70], or 0.558 g of P4 and prostaglandin F2α (PGF2α) [150 �g d-cloprostenol, IM, Croniben�, Biogenesis; Treatment 3 (T3), n = 75], or 1 g of P4 and PGF2α [Treatment 4 (T4), n = 71]. At the time of intravaginal device insertion (Day 0 = D0), all animals received 2 mg of estradiol benzoate (EB, Bioestrogen�, IM, Biogenesis), and PGF2α was administered only in animals from groups T3 and T4. Eight days later (D8), PGF2α (0.150 g d-cloprostenol) was administered to all heifers and the P4 source was removed. Twenty-four h after removal of the intravaginal device, the heifers were treated with EB (1 mg, IM), and 30 to 36 h later all animals were fixed-time inseminated (FTAI, D10), without estrus detection. In a subset of heifers from each group (T1 = 28; T2 = 34; T3 = 33; T4 = 31), ovarian ultrasonography was performed on D9 (at 8:00 A.M.) and D11 (at 14:00 P.M.) in order to determine ovulation rate after each treatment. The data were analyzed by logistic regression (GENPROC, SAS; SAS Institute, Inc., Cary, NC, USA). Ovulation rates after treatments T1, T2, T3, and T4, were, respectively, 71.4% (20/28), 76.5% (26/34), 84.9% (28/33), and 70.9% (22/31), and there was no significant difference among groups (P > 0.05). Pregnancy rates, ascertained by ultrasonography 40 days after AI, were 30.2% (23/76), 25.7% (18/70), 33.3% (25/75), and 28.2% (20/71), respectively, for T1, T2, T3, and T4, and likewise there was no significant difference among groups (P > 0.05). It is concluded that reduction of progesterone concentration in the intravaginal device (1 g v. 0.558 g) associated or not with administration of PGF2α at the beginning of treatments did not significantly influence ovulation and pregnancy rates in Nelore heifers submitted to a FTAI protocol. Additional experiments are underway to confirm or not the present results. This work was supported by FAPESP (Brazil) and BIOGENESIS (Argentina).

115 Presynchronization and reutilization of progesterone devices during a 6-day CO-Synch protocol for fixed-time artificial insemination in beef heifers

2021 ◽  
Vol 33 (2) ◽  
pp. 165
Author(s):  
E. R. Canadas ◽  
B. Duran ◽  
G. Machado ◽  
A. Nall ◽  
S. E. Battista ◽  
...  
Keyword(s):  
Factorial Design ◽  
Artificial Insemination ◽  
Fixed Time ◽  
P Value ◽  
Beef Heifers ◽  
Follicle Diameter ◽  
Follicle Size ◽  
Gonadotrophin Releasing Hormone ◽  
Intravaginal Device ◽  
Second Use

Ovulatory response to the initial gonadotrophin-releasing hormone (GnRH) of the CO-Synch protocol is affected by circulating progesterone (P4) and follicle size. In addition, heifers that ovulate to initial GnRH treatment have greater fertility after AI. Thus, the aim of this study was to assess the effect of (1) presynchronization (Presynch) before a 6-day CO-Synch protocol and (2) P4 device reuse (new vs. second use) on ovulatory response, oestrous expression, and pregnancy per AI (P/AI) in beef heifers. Yearling beef heifers (n=233) were randomly assigned in a 2×2 factorial design to the following treatments: (1) Treatment (Presynch): (1a) Presynch+6-day CO-Synch with new P4 device; (1b) Presynch+6-days CO-Synch with a once-used P4 device; (2) Control (no Presynch): (2a) 6-day CO-Synch with new P4 device; (2b) 6-day CO-synch with once-used P4 device. Presynch consisted of insertion of a new P4 intravaginal device (CIDR, 1.38g of P4; Zoetis) on Day −17 and removal of the CIDR on Day −11 concurrently with 500µg of cloprostenol sodium. On Day −9, all heifers received either a new or once-used (used) CIDR and 100µg of gonadorelin acetate (GnRH, Parnell Inc.). Six days later (Day −3) CIDRs were removed, 1000µg of PGF was administered, and an oestrous detection patch applied (Estrotect, Rockway Inc.). At 72h after CIDR removal, 100µg of GnRH and AI using 3 different sires was performed. Pregnancy was determined by ultrasonography 31 days after AI. A subset of heifers (n=151) were examined on Day −9 and Day −3 by ultrasonography to assess ovulation to Day −9 GnRH. Data were analysed using GLIMMIX (SAS 9.4; SAS Institute Inc.). Presynch heifers had larger follicle diameter on Day −9 (12.7±0.3 vs. 10.4±0.3 mm; P&lt;0.0001), greater ovulatory response (84.6%; 66/78 vs. 52.05%; 38/73; P&lt;0.0001), greater oestrus expression (90.6%; 106/117 vs. 78.4%; 91/116; P=0.03), and expressed oestrus earlier (49.8±1.0 vs. 53.1±1.1 h; P=0.01) compared with controls. There was an interaction for treatment and CIDR on oestrous expression, whereas a lesser (P=0.003) percentage of control heifers with new CIDR showed oestrus compared with all other groups (Table 1). Heifers treated with a used P4 device tended (P=0.08) to have greater P/AI (52.1%; 61/117) than those with a new CIDR (40.5%; 47/116). In conclusion, presynchronization before initiation of a 6-day CO-Synch increased follicle diameter, ovulatory response, and oestrous expression, but did not affect fertility. The earlier onset of oestrus in Presynch heifers warrants further study on timing of AI. Table 1. Oestrous expression and pregnancy per AI (P/AI) in beef heifers with or without presynchronization and treated with a new or used CIDR Treatment CIDR Oestrus (%; n/n) Time of oestrus (h) P/AI (%; n/n) Control New 67.8a (40/59) 53.7±1.5a 33.9 (20/59) Used 89.5b (51/57) 52.7±1.6a 50.9 (29/57) Presynch New 94.7b (54/57) 50.9±1.4b 47.4 (27/57) Used 86.7b (52/60) 48.7±1.3b 53.3 (32/60) P-value Treatment 0.03 0.01 0.21 CIDR 0.62 0.18 0.08 Interaction 0.003 0.78 0.38 a,bValues with different superscripts differ (P &lt; 0.05).

scholarly journals Effects of prolonging the interval from progestin removal to prostaglandin F2α injection from 16 to 17 days in a long-term estrus synchronization protocol in beef heifers

2021 ◽  
Author(s):  
N Oosthuizen ◽  
G D Melo ◽  
G E Seidel ◽  
R L Stewart ◽  
L Rowden ◽  
...  
Keyword(s):  
Prostaglandin F2α ◽  
Fixed Time ◽  
Transrectal Ultrasonography ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Treatment Groups ◽  
Follicle Diameter ◽  
Randomized Design ◽  
Angus Heifers

Abstract To determine effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG protocol, 1,049 Angus heifers at six locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to one of two treatment groups: 1) PG16 (n = 518), heifers received a controlled internal drug release (CIDR) insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal (Day 30), and a 100-µg injection of gonadotropin-releasing hormone concurrent with TAI 66 ± 2 h later; or 2) PG17 (n = 531), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal (Day 31), and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to a subset (n = 482) of heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 116). Transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI differed by treatment where PG17 heifers had greater (P &lt; 0.01) expression of estrus than PG16 heifers (57.8 ± 6.1 vs. 43.4 ± 6.1%, respectively). Nevertheless, dominant follicle diameters at PGF and at TAI were similar (P ≥ 0.59) between PG16 and PG17 heifers. In addition, PR/AI did not differ (P = 0.29) between PG16 and PG17 treatments (50.5 ± 3.2 vs. 45.7 ± 3.1%, respectively). Results of this experiment indicate that delaying the injection of PGF and TAI in the 14-day CIDR-PG protocol increased estrus expression prior to TAI yet did not improve fertility in beef heifers.

scholarly journals PSII-29 Effects of delayed injection of prostaglandin F2α and TAI in the 14-d CIDR-PG & TAI protocol in replacement beef heifers

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 375-376
Author(s):  
Nicky Oosthuizen ◽  
Gabriela Melo ◽  
Lawton Stewart ◽  
George Seidel ◽  
Graham Cliff Lamb ◽  
...  
Keyword(s):  
Prostaglandin F2α ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Transrectal Ultrasonography ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Treatment Groups ◽  
Follicle Diameter ◽  
Randomized Design ◽  
Angus Heifers

Abstract To determine the effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG & TAI protocol, 911 Angus heifers at 5 locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to 1 of 2 treatment groups: 1) PG16 (n = 452), heifers received a CIDR insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal [d 30], and a 100-µg injection of gonadotropin-releasing hormone concurrently with TAI 66 ± 2 h later; or 2) PG17 (n = 459), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal [d 31], and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 171). Furthermore, transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI was similar (P = 0.50) between treatments (48.9 vs. 52.0%, respectively). Moreover, dominant follicle diameter at PGF and TAI was similar (P ≥ 0.43) between PG16 and PG17 heifers. Pregnancy rates to TAI did not differ (P = 0.48) between treatment groups (46.4 vs. 48.9%, respectively). The results of this experiment indicate that delaying the injection of PGF from d 30 to d 31 along with TAI in the 14-day CIDR-PG & TAI protocol had no effects on fertility parameters in beef heifers. In conclusion, the PGF injection and TAI in the 14-d CIDR-PG & TAI protocol may be delayed, providing more flexibility in scheduling without negatively affecting fertility.

30 OVULATION AND PREGNANCY RATES IN CYCLING NELLORE HEIFERS AFTER FIXED-TIME ARTIFICIAL INSEMINATION PROTOCOLS USING DIFFERENT CONCENTRATIONS OF PROGESTERONE, ASSOCIATED OR NOT WITH eCG

2010 ◽  
Vol 22 (1) ◽  
pp. 173
Author(s):  
M. F. Pegorer ◽  
R. L. Ereno ◽  
R. A. Satrapa ◽  
C. M. Barros
Keyword(s):  
Hormonal Treatment ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Repeated Measurements ◽  
Blood Levels ◽  
Dominant Follicle ◽  
Device Removal ◽  
Follicle Diameter ◽  
Intravaginal Device

The objective of the present study was to evaluate the influence of different P4 concentrations, associated or not with eCG, in the ovulation and pregnancy rates of Nellore heifers submitted to hormonal protocols for FTAI. In experiment (exp.) 1, heifers (n = 15) presynchronized with a hormonal treatment were randomly allocated in 4 groups. At the time of intravaginal device insertion (Day 0) all animals received 2 mg of estradiol benzoate (EB) and a intravaginal progesterone-releasing device containing 0.558 g of P4 (Triu®, Biogenesis Bago, Buenos Aires, Argentina; group 0.5G, n = 4) or 1g of P4 (Cronipres®, Biogenesis Bago; group 1G, n = 4), or 0.558 g of P4 and PGF2α (150 μg of D-cloprostenol, group 0.5G/PGF, n = 4), or 1 g of P4 and PGF2α (group 1G/PGF, n = 3). Eight days later (Day 8), PGF2α (150 μg D-cloprostenol) was administered to all heifers, and the P4 source was removed. Twenty-four hours after removing the intravaginal device (Day 9), the heifers were treated with EB (1 mg, i.m.). Blood samples were collected on Days 0, 1, 2, 4, 8, and 10 to evaluate plasma P4 concentration. In exp. 2, cycling Nellore heifers (n = 292) were treated with the same protocols as in the exp. 1. However, 30 to 36 h later all animals were FTAI on Day 10. In exp. 3, heifers (n = 459) received the treatments described for groups 0.5G/PGF and 1G/PGF associated with 300 IU of eCG (i.m. groups 0.5G/PGF/eCG and 1G/PGF/eCG) at the time of intravaginal device removal (Day 8). In a subset of heifers from each group, ovarian ultrasonography was performed to determine the diameter of the dominant follicle on Day 9 (exp.3) and the ovulation rate on Day 12 (exp. 2 and 3). ANOVA for repeated measurements was used to compare P4 levels, and the binary variables (ovulation and pregnancy rates) were analyzed by logistic regression. In exp. 1, P4 concentrations were higher in animals that received 1.0 compared with 0.558 g of P4, and lower in heifers that received PGF2α on Day 0. In both exp. 2 and 3 there were no significant differences in ovulation (65 to 77%) and pregnancy (exp.2: 26 to 33%; exp.3: 39 to 43%) rates among the several groups. In exp. 3, the animals that received 0.558 g of P4 had a larger diameter of the dominant follicle on Day 9 compared with heifers treated with 1.0 g (10.3 ± 0.2 v. 9.3 ± 0.2 mm; P < 0.01). It is concluded that reduction of P4 concentration in the intravaginal device or the administration of PGF2α at the beginning of the treatments decreases blood levels of P4 between Days 1 and 8 of the FTAI protocols. However, although the use of intravaginal devices with lower P4 contributed to increase the dominant follicle diameter on Day 9, there was no significant increase on ovulation and pregnancy rates. Additionally, the association of eCG with FTAI protocols did not improve follicular growth or ovulation and pregnancy rates. Supported by FAPESP (Sao Paulo, Brazil).

163 Treatment with gonadotrophin-releasing hormone at the time of AI in beef heifers that fail to express oestrus after an estradiol-based synchronisation protocol improves pregnancies per AI

2020 ◽  
Vol 32 (2) ◽  
pp. 208
Author(s):  
A. Butler ◽  
H. Butler ◽  
G. Cesaroni ◽  
R. Alberio ◽  
S. Perez Wallace ◽  
...  
Keyword(s):  
Pregnancy Loss ◽  
Fixed Time ◽  
P Value ◽  
Device Removal ◽  
Releasing Hormone ◽  
Condition Score ◽  
Gonadotrophin Releasing Hormone ◽  
To Receive ◽  
Angus Heifers ◽  
Intravaginal Device

Oestrus expression between progesterone (P4) withdrawal and fixed-time AI (FTAI) has been shown to improve pregnancies per AI (P/AI) by 27% in beef cattle. As a result, cattle that do not express oestrus after P4 withdrawal present a challenge to the efficiency of FTAI. The present study was designed to test the hypothesis that administration of gonadotrophin-releasing hormone (GnRH) at the time of AI in heifers that do not express oestrus can improve fertility. Two-year-old Angus heifers (n=1032) with a condition score of 2.75 to 3.5 at two locations in Argentina were used. On Day 0, heifers received an intravaginal device containing 0.5g of P4 (Cronipres, Biogenesis) and 2mg of oestradiol benzoate intramuscularly (Bioestrogen, Biogenesis). On Day 8, devices were removed and heifers received 150µg of d-cloprostenol intramuscularly (Enzaprost, Biogenesis), 0.5mg of oestradiol cipionate intramuscularly (Croni-Cip, Biogenesis), and an oestrus detection patch (Estrotect, Rockway Inc.). On Day 10, AI was performed in all heifers 50 to 54h after device removal. Heifers were categorised based on oestrus expression, and those that did not express oestrus were randomised to receive 100µg of gonadorelin acetate intramuscularly (Gonasyn, Syntex; n=158) concurrent with AI or remain as untreated controls (n=151). Pregnancy was determined using ultrasonography at Days 38 and 111 after AI. Differences in fertility were evaluated using generalised linear mixed models, and the results are shown in Table 1. Oestrus expression between device removal and FTAI was 70.1% (723/1032). Pregnancies per AI at Days 38 and 111 were different between groups (P&lt;0.01). Heifers that expressed oestrus had greater P/AI than those that did not regardless of treatment (P&lt;0.01). However, in heifers that did not express oestrus, treatment with GnRH at the time of AI resulted in greater P/AI than in control heifers (P=0.004). Similarly, P/AI at Day 111 were greater in heifers that expressed oestrus than in those that did not regardless of treatment (P&lt;0.01). Heifers that did not express oestrus and were treated with GnRH had greater P/AI than those that did not express oestrus and remained as controls (P=0.02). Pregnancy loss between Days 38 and 111 was not different between groups; however, there was a tendency (P=0.06) for greater pregnancy loss in heifers that did not express oestrus and were treated with GnRH compared with heifers that expressed oestrus. In summary, treatment with GnRH at the time of AI is a suitable strategy to improve P/AI in heifers that fail to exhibit oestrus after an oestradiol-based synchronisation protocol. However, this strategy appears to increase pregnancy loss, and thus further research is needed to confirm this observation and the mechanisms underlying it. Table 1.Pregnancies per AI (P/AI) and pregnancy loss (%; no. in parentheses) in Angus heifers based on oestrus expression and treatment with GnRH Group P/AI Day 38 P/AI Day 111 Pregnancy loss Oestrus 68.9 (498/723)A 65.2 (471/723)A 5.4 (27/498) No oestrus control 29.8 (45/151)B 28.5 (43/151)B 4.4 (2/45) No oestrus + GnRH 45.6 (72/158)C 40.5 (64/158)C 11.1 (8/72) P-value &lt;0.001 &lt;0.001 0.15 A-CValues within a column with different superscripts differ significantly (P&lt;0.05).

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