STRATEGIES TO INCREASE FERTILITY DURING FIXED-TIME ARTIFICIAL INSEMINATION IN BEEF CATTLE

The application of Fixed Time Artificial Insemination (FTAI) protocols has strongly boosted artificial insemination in Brazilian bovine herds. The control of the estrous cycle with protocols based on progesterone and estrogen involves synchronizing the emergence of a follicular wave, controlling the progesterone phase, and inducing ovulation in a synchronized manner. The increase in pregnancy rates starts with the preparation of the breeding season and the choice of protocols and females. Thereafter, based on the characteristics of the property and the lots of animals, small adjustments can be made to the hormonal protocols as needed. Finally, resynchronization can increase usability by allowing multiple inseminations within short periods. The search for new strategies is of paramount importance for the development of the FTAI protocol and the increase in final pregnancy rates. Thus, this review sought to highlight the main critical points and adjustments of the FTAI protocols and their applicability in the reproduction of beef cattle.

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Parenteral Copper Administration at the Beginning of a Fixed-Time Artificial Insemination Protocol in Beef Cattle: Effect on Ovarian Function and Pregnancy Rates

Biological Trace Element Research ◽

10.1007/s12011-021-02795-y ◽

2021 ◽

Author(s):

Juan Patricio Anchordoquy ◽

Santiago Nicolás Lorenti ◽

Gustavo Sebastián Polero ◽

Nicolás Agustín Farnetano ◽

Diana Esther Rosa ◽

...

Keyword(s):

Beef Cattle ◽

Artificial Insemination ◽

Ovarian Function ◽

Fixed Time ◽

Pregnancy Rates

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Response of beef heifers and non-suckling beef cows to different oestrous synchronization protocols

Animal Science ◽

10.1017/s135772980005270x ◽

2002 ◽

Vol 74 (3) ◽

pp. 547-552 ◽

Cited By ~ 3

Author(s):

D. Cavestany ◽

N. Negrin ◽

R. Negrin ◽

J. F. Groth

Keyword(s):

Beef Cattle ◽

Medroxyprogesterone Acetate ◽

Artificial Insemination ◽

Experimental Period ◽

Fixed Time ◽

Beef Cows ◽

Pregnancy Rates ◽

Gnrh Analogue ◽

Beef Heifers

AbstractThe objective was to evaluate different oestrous synchronization schemes in beef cattle under range conditions. In experiment 1, 202 heifers averaging 26 months of age were assigned randomly to three treatments: (a) GnRH-PG. (no. = 44) day 0 (D0): injection of GnRH; D7: injection of PGF2α; D0 to D25 oestrous detection (OD) and artificial insemination (AI); (b) OD-PG. (no. = 45) D0 to D4; OD + AI; D5: injection of PGF2α; D5 to D25 OD + AI; and (c)Ovsynch. (no. = 113) D0: injection of GnRH; D7: injection of PGF2α; D9: injection of GnRH and 16 h later AI at fixed time. In experiment 2, 318 non-suckling cows were assigned randomly to three treatments: (a) GnRH-PG. (no. = 106) D0: injection of GnRH; D7: injection of PGF2α; D0 to D25 OD + AI; (b) GnRH-MAP-PG. (no. = 106) D0: injection of a GnRH analogue and insertion of an intravaginal sponge impregnated with 250 mg of medroxyprogesterone acetate; D7: injection of PGF2α and sponge withdrawal; D0 to D25 OD + AI; (c) controls. (no. = 106) OD and AI. The experimental period lasted 25 days and, with exception of the Ovsynch treatment, oestrous detection was carried out twice a day (a.m./p.m.) and inseminations performed 12 h later. The pregnancy rates assessed by ultrasonography 30 days after AI were: experiment 1: (a) 30·0%; (b) 28·6% and (c) 62·3% (P < 0·05); experiment 2: (a) 60·2%; (b) 57·8% and (c) 45·5% (P < 0·05). It is concluded that in heifers and non-suckling cows, oestrous synchronization treatments result in higher pregnancy rates. In non-suckling cows, the addition of a progestagen did not improve the response.

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Cooled semen for fixed-time artificial insemination in beef cattle

Reproduction Fertility and Development ◽

10.1071/rd14185 ◽

2016 ◽

Vol 28 (7) ◽

pp. 1004 ◽

Cited By ~ 9

Author(s):

Juliana C. Borges-Silva ◽

Márcio R. Silva ◽

Daniel B. Marinho ◽

Eriklis Nogueira ◽

Deiler C. Sampaio ◽

...

Keyword(s):

Beef Cattle ◽

Sperm Motility ◽

Artificial Insemination ◽

Egg Yolk ◽

Fixed Time ◽

Pregnancy Rates ◽

Reproductive Efficiency ◽

Sperm Abnormalities ◽

Hypoosmotic Swelling Test ◽

Interesting Approach

This study evaluated the use of cooled semen in a fixed-time artificial insemination (FTAI) program compared with frozen–thawed semen to improve pregnancy rates in beef cattle. Ejaculates of three bulls were collected and divided into two treatments: (1) frozen–thawed semen and (2) cooled semen. Egg-yolk extender without glycerol was used for the cooled semen treatment. Straws (25 × 106 spermatozoa) were submitted to cooling for preservation at 5°C for 24 h, after which FTAI was performed. Nelore cows (n = 838) submitted to FTAI were randomly inseminated using frozen–thawed semen or cooled semen. There was a 20% increase in the pregnancy per AI (P AI–1) using cooled semen compared with frozen–thawed semen (59.9 ± 4.7 vs 49.4 ± 5.0%; P < 0.005). There was no difference in P AI–1 among the bulls (P = 0.40). The frozen–thawed semen had fewer functional spermatozoa than did the cooled semen when evaluated by sperm motility (61.7 vs 81.0%), slow thermoresistance test (41.7 vs 66.7%) and hypoosmotic swelling test (38.3 vs 53.7%; P < 0.05). The percentage of sperm abnormalities did not differ between the freeze–thawing and cooling processes (18.6 vs 22.1%; P > 0.05). Because there was less damage to spermatozoa and improvement in P AI–1, the use of cooled semen instead of frozen–thawed semen is an interesting approach to increase reproductive efficiency in cattle submitted to a FTAI protocol.

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Control of the estrous cycle to improve fertility for fixed-time artificial insemination in beef cattle: A review1

Journal of Animal Science ◽

10.2527/jas.2009-2349 ◽

2010 ◽

Vol 88 (suppl_13) ◽

pp. E181-E192 ◽

Cited By ~ 55

Author(s):

G. C. Lamb ◽

C. R. Dahlen ◽

J. E. Larson ◽

G. Marquezini ◽

J. S. Stevenson

Keyword(s):

Beef Cattle ◽

Estrous Cycle ◽

Artificial Insemination ◽

Fixed Time

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113 Influence of cattle stress response to restraint method on artificial insemination pregnancy rates

Journal of Animal Science ◽

10.1093/jas/skz053.093 ◽

2019 ◽

Vol 97 (Supplement_1) ◽

pp. 41-42

Author(s):

Russell C Carrell ◽

William B Smith ◽

Lea A Kinman ◽

Vitor R G Mercadante ◽

David Roper

Keyword(s):

Pregnancy Rate ◽

Stress Responses ◽

Artificial Insemination ◽

Bos Taurus ◽

Physiological Stress ◽

Negative Impact ◽

Fixed Time ◽

Pregnancy Rates ◽

Restraint Mechanism ◽

In Pregnancy

Abstract Activation of physiological stress responses have been associated with decreased pregnancy rates in beef cattle. Therefore, alternative cattle restraint methods have been developed to reduce this negative impact. However, little evidence exists comparing pregnancy outcomes of differing methods. Thus our objective was to determine if a difference was present in pregnancy rate to fixed-time artificial insemination in Bos taurus beef females when using a breeding box (b) versus a squeeze chute (c). Cows and heifers from two separate locations (Virginia Tech University, VT; and R.A. Brown Ranch, RAB) were exposed to FTAI protocols at location of origin while restrained in a squeeze chute (n = 169) or a breeding box (n = 162). Females were exposed to the 7 day Co-Sync + CIDR protocol pre-breeding. At day of breeding, females were randomly assigned to treatment. Immediately following breeding, blood was collected via coccygeal venipuncture for assessment of plasma cortisol concentration using an automated ELISA assay (Immulite 2000 XPi, Siemens). Chute and Exit Score (1–5) were assessed at the time of breeding by a trained technician at each location. Pregnancy was verified thirty days post-breeding via rectal ultrasonography. Pregnancy rate (PROC FREQ) and cortisol (PROC GLIMMIX) were analyzed using SAS version 9.4. Also, a Linear Regression Model (SAS version 9.4) was used to determine relationships between chute score, exit score, and cortisol. It was found that there was no difference in pregnancy rate between the breeding box and the squeeze chute (61.73% vs 64.71%, P = 0.31, respectively). Cortisol showed no difference between b and c (59.44±10.17 vs 58.61±10.16, P = 0.68, respectively). There was no linear relationship between cortisol, exit score, and chute score (P = 0.14). It can be concluded that stress responses are similar between the breeding box and squeeze chute. Therefore females will have similar pregnancy rates when exposed to FTAI in either restraint mechanism.

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Comparative Study Between Different Methods of Insemination in Iraqi Does

The Iraqi Journal of Veterinary Medicine ◽

10.30539/iraqijvm.v35i2.581 ◽

2011 ◽

Vol 35 (2) ◽

pp. 95-104

Author(s):

HA . AL-Mutar

Keyword(s):

Comparative Study ◽

Pregnancy Rate ◽

Breeding Season ◽

Artificial Insemination ◽

Fixed Time ◽

Experimental Animals ◽

Pregnant Mare Serum Gonadotropin ◽

Abdominal Palpation ◽

Serum Gonadotropin ◽

In Pregnancy

Present experimental was carried out on 22 does 2-4 years old. The aim was to induction of estrous in non-breeding season using impregnated sponge with 20 mg of medroxy progesterone acetate (MPA) for 13 days and with an i/m injection of 500 IU Pregnant Mare Serum Gonadotropin (PMSG) hormone 24 hrs before sponge withdrawal and to compare the pregnancy rate using three different methods of insemination; natural , cervical and laparoscopic artificial insemination at fixed time 24-48 hrs after estrous onset. All does were showed signs of estrous (100%), the estrous time was 46.9±4.90hrs (24-60hrs) after sponge withdrawal. While estrous length was 37.09±1.91 (24–72hrs). All experimental animals followed up by abdominal palpation, ultrasonography at 30, 60 and 90 days post-insemination, while the laparoscopic examination was performed at day 30 post-insemination, to improve the efficiently of the different methods of inseminations in pregnancy rate ultrasonographical diagnosed by rectal and abdominal methods of 14 does post-inseminations appeared that two were pregnant, seven suspected and five non pregnant. At day 60th , post-insemination the pregnancy diagnosis of (22) does appeared that (14) were pregnant, six suspected and two non pregnant. While at day 90, the examination of all does appeared that (16) animals were pregnant and six were not. The laparoscopic examination, at 30 days post-insemination showed that eight does were pregnant, two suspected and two were not pregnant. In conclusion that the pregnancy rate of laparoscopic insemination is (75%), comparisons to natural (66.7%) and cervical AI method (75%) but there is no significant different between them, while the kidding percentage was appear in natural insemination (75%), cervical (100%) and laparoscopic insemination (150%). The results of this study indicate that estrus can be efficiently induced in female goats during non-breeding season using 20mg MPA impregnated spongewith 500IU PMSG.

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Reproductive efficiency Nellore and crossbred cows submitted to administration of melengestrol acetate (MGA) after FTAI protocols

Research Society and Development ◽

10.33448/rsd-v9i10.8897 ◽

2020 ◽

Vol 9 (10) ◽

pp. e5679108897

Author(s):

Alan Gabriel Valero ◽

Carlos Renato de Freitas Guaitolini ◽

Andre Maciel Crespilho ◽

Gabriela Passamani da Cruz ◽

Marcio Luiz Denck Tramontin ◽

...

Keyword(s):

Statistical Analysis ◽

Breeding Season ◽

Medroxyprogesterone Acetate ◽

Artificial Insemination ◽

Fixed Time ◽

Pregnancy Rates ◽

Conception Rate ◽

Reproductive Efficiency ◽

Crossbred Cows ◽

Melengestrol Acetate

This study aimed to evaluate the influence of medroxyprogesterone acetate (MGA) supplementation between the 13th and 20th day after Fixed-Time-Artificial Insemination (FTAI), on the conception and gestation rates of Nellore and crossbred cows (Nellore x Angus), pluriparous and lactating. For the study, 349 Nellore cows and 270 crossbred cows were selected, distributed into 1) group G1 (n=176): Nellore cows submitted to the FTAI protocol, without MGA supplementation; 2) group G2 (n=173): Nellore cows submitted to the FTAI protocol, with supplementation for 7 days of MGA® (0.28g/AU/day) from the 13th post-FTAI; 3) group G3 (n=119): crossbred cows: FTAI protocol, without MGA supplementation; 4) group G4 (n=151): crossbred cows: FTAI protocol followed by MGA supplementation for 7 days (0.28g/AU/day), from the 13th to the 20th day after FTAI. For statistical analysis, the procedures MIXED and GLIMMIX from SAS were used. G3 had higher rates of conception (CR=85.7%) and pregnancy (PR=95.8%) at the end of the breeding season (P<0.05), without the interference of supplementation with MGA (P>0.05). G1 females had a lower conception rate (TC=76.7%) (P<0.05), with the use of MGA® (CR-MGA=59.5%), but similar rates of pregnancy (PR=90.3%; PR-MGA=92.5%) to the G2, at the end of the breeding season (P>0.05). When G2 and G4 were compared, we found that crossbred females supplemented had higher rates of conception and pregnancy. In conclusion, crossbred animals have higher conception and pregnancy rates at the end of the breeding season. Besides, we found that Nellore females had a lower conception rate, with the use of MGA® Premix.

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14 SYNCHRONIZATION OF OVULATION IN ANESTROUS NELORE COWS TREATED WITH HORMONAL PROTOCOL WITHOUT PROGESTERONE OR PROGESTAGENS

Reproduction Fertility and Development ◽

10.1071/rdv18n2ab14 ◽

2006 ◽

Vol 18 (2) ◽

pp. 115 ◽

Cited By ~ 1

Author(s):

A. F. Souza ◽

V. G. Pinheiro ◽

R. L. Ereno ◽

C. M. Barros

Keyword(s):

Estrous Cycle ◽

Fixed Time ◽

Estradiol Benzoate ◽

Pregnancy Rates ◽

Preovulatory Follicles ◽

Estrus Detection ◽

Calf Removal ◽

D 12 ◽

Hormonal Treatments ◽

In Pregnancy

Postpartum anestrous cows are usually treated with progesterone/progestagen protocols in order to induce ovulation and sustain pregnancy. In the present work, the efficiency of a protocol (modified GPE), in which temporary calf removal (TCR) and/or administration of eCG, replaced the use of progesterone/progestagens, was evaluated in anestrous animals. Anestrous Nelore cows (40 to 60 days postpartum, n = 22) were randomly allocated to two groups: GPE/eCG and TCR/GPE/eCG. At a random stage of the estrous cycle (D0), animals from Group GPE/eCG were treated with GnRH (50 �g, licereline, i.m., Gestran Plus�; Tecnopec, Sao Paulo, Brazil) and seven days later (D7) they received PGF2� (150 mcg, d-cloprostenol, i.m., Prolise�) and eCG (300 UI, i.m., Novormon�). On D8, estradiol benzoate (EB, 1 mg, Estrogin�; Tecnopec) was administered, and 30 to 36 h afterwards all cows were inseminated at fixed-time (FTAI), without estrus detection. The animals from group TCR/GPE/eCG received the same treatment described above, but with temporary calf removal (during 48 h) before beginning hormonal treatments. The ovaries were examined by ultrasonography (Aloka SSD 500, 7.5 MHz probe) before (D-12, D-2), during (D0, D7, D8), and after (D9, D10, D11, D17, D60) hormonal treatments. The absence of CL, during the ultrasonography performed before starting the treatments, was the criterion used to classify the cows as in postpartum anestrus. Administration of GnRH (D0) induced ovulation (determined by the presence of CL on D7) in 6 of 11 cows (54.5%) from Group GPE/eCG and TCR/GPE/eCG. In relation to synchronization of ovulation after EB administration, in Group GPE/eCG, two cows (18.1%) ovulated until 12 h after FTAI, and four (36.3%) 12 h afterwards (24 h after FTAI). In Group TCR/GPE/eCG, one cow (9%) ovulated approximately 6 h before FTAI, two (18.1%) 12 h after FTAI, and two (18.1%) 12 h afterwards. Preovulatory follicles had a diameter of 11.0 � 1.3 and 11.5 � 2.6 mm in Groups GPE/eCG and TCR/GPE/eCG, respectively. Pregnancy rates, determined by ultrasonograpy 40 to 46 days after FTAI, were 27.2% (3/11) and 45.4% (5/11), respectively. The results indicate that association of TCR with protocol GPE/eCG did not improve synchronization of ovulation or pregnancy rates (P > 0.005). However, increase in pregnancy rates was observed in another experiment with a large number of animals (Pinheiro et al. 2005 Reprod. Fert. Dev. 17, 161, abstr), in which cows from Group TCR/GPE/eCG had higher pregnancy rates (51.5%; 34/66) when compared to animals from Group GPE/eCG (28.3%, 21/74; P < 0.05). This work was supported by FAPESP and by fellowships for A. F. Souza and V. G. Pinheiro from CNPq, Brazil.

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Effects of postpartum energy intake on pregnancy rates in beef cattle subjected to GnRH- or CIDR-based timed artificial insemination protocols

Canadian Journal of Animal Science ◽

10.4141/cjas07128 ◽

2008 ◽

Vol 88 (3) ◽

pp. 439-447 ◽

Cited By ~ 2

Author(s):

J. J. Wichtel ◽

E. Charmley ◽

G. F. Richardson ◽

J. L. Duynisveld ◽

R. Lofstedt

Keyword(s):

Beef Cattle ◽

Energy Intake ◽

Artificial Insemination ◽

Body Condition Score ◽

Post Partum ◽

Fixed Time ◽

Estradiol Benzoate ◽

Pregnancy Rates ◽

Estradiol Treatment ◽

Serum Progesterone

The objectives were to determine the effects of three levels of postpartum metabolisable energy (ME) intake on pregnancy rates in beef cattle subjected to either GnRH-based (OVS) or progestin-based (CIDR) protocols for fixed time artificial insemination (TAI). Hereford cross cows were assigned to ME and TAI treatments (within ME) on the basis of parity and predicted calving date. The postpartum grass-silage-based diet was formulated to provide either Low (93 MJ d-1), Medium (103 MJ d-1) or High (120 MJ d-1)] ME from calving (January to February) to turnout (May 25). Lactating cows [n = 175, 5.7 ± 1.1 mean (± SD) body condition score at calving] were subjected to their assigned TAI protocol; OVS [i.m. treatments of GnRH (100 μg) on day 0, PGF2α (25 mg) on day 7, a second GnRH on day 9 and TAI 16 to 18 h later], or CIDR [i.m. treatment with 1 mg estradiol benzoate and 100 mg progesterone concurrent with CIDR (1.9 g progesterone) insertion on day 0, PGF2α treatment at CIDR removal on day 7, a second estradiol treatment on day 8 and TAI 28 to 30 h later). Cows were 60 ± 13 d post-partum at the time of insemination. Lower ME intakes reduced (P < 0.05) maternal body weight and calf weight gain, but ME intake did not affect (P > 0.05) the proportion cycling (113/175 = 65%, based on serum progesterone concentrations on days -5 and -14), ovulation following TAI, or the TAI pregnancy rates (based on ultrasonography). Timed insemination pregnancy rates were greater for CIDR- than OVS-treatment (63 vs. 45%, respectively, P < 0.05), regardless of ME intake. Key words: Beef cow, estrus synchronization, Ovsynch, CIDR, energy intake, reproduction, calf gains

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