49 USE OF DILUTION OF CRYOPRESERVED SEMEN IN FIXED-TIME ARTIFICIAL INSEMINATION OF MANGALARGA MARCHADOR MARES

2012 ◽  
Vol 24 (1) ◽  
pp. 136
Author(s):  
M. B. R. Nogueira ◽  
A. C. F. Farinasso ◽  
A. C. Rezende ◽  
T. L. C. Pinto ◽  
J. C. Souza
Keyword(s):  
Osmotic Stress ◽  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Binomial Distribution ◽  
Osmotic Shock ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Ovulatory Follicle ◽  
Frozen Semen

Equine AI with frozen semen has become more frequent in reproduction centers, but osmotic shock during thawing is still a major problem as it impairs gamete viability and fertility. To overcome this, multi ultrasonographic (US) exams must be performed to ensure AI at the closest time to ovulation possible. The objective was to evaluate, in vivo, the effects of dilution of the cryoprotectant dimethylphormamide on the success of a fixed timed (20 h post-ovulation) AI protocol, in an attempt to reduce osmotic shock and the intense labour usually required during equine AI with frozen semen. Thirty-five Mangalarga Marchador mares were used in this trial. When dominant follicles reached at least 35 mm in diameter, ovulation was induced with 6 mg of equine gonadotrophin extract (EGE) intravenously. Artificial insemination was performed 20 h after ovulation according to 1 of the following protocols: no dilution (n = 14): three 0.5-mL straws were thawed and the semen deposited by a flexible rod at the uterine tip in the ipsilateral horn where the pre-ovulatory follicle was detected; or dilution (n = 21): three 0.5-mL straws were thawed as described and centrifuged after addition of 1.5 mL of BotuSêmen® extender (1:1 dilution). Pregnancy rates were evaluated between treatments, age and presence of intrauterine liquid (IUL) classes and period between ovulation and AI. Data were analysed as a binomial distribution with the GENMOD procedure (SAS, Cary, NC, USA). Pregnancy rate was higher (P < 0.05) for mares inseminated with diluted semen (42.9%) compared to those inseminated with no semen dilution (4.8%). Age and IUL class did not influence pregnancy rates. It can be concluded that reduction of osmotic stress through the dilution of cryopreserved equine semen increased pregnancy rates after AI. Semen dilution, as tested in this trial, yielded good pregnancy rates in a fixed-time AI protocol in mares, simplified mare management greatly and allowed the use of a fixed-time protocol successfully. Supported by CNPQ, CAPES.

scholarly journals Effect of progesterone, human chorionic gonadotropin and progesterone + human chorionic gonadotropin treatment on conception rates in repeat breeder cows

2020 ◽  
Vol 89 (4) ◽  
pp. 307-315
Author(s):  
Hasan Alkan ◽  
Huseyin Erdem
Keyword(s):  
Pregnancy Rate ◽  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Artificial Insemination ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Group 4 ◽  
Prostaglandin F ◽  
Repeat Breeder ◽  
Group 1

The aim of this study was to investigate the effects of hormonal support on the pregnancy rate in repeat breeder cows. Prostaglandin F2α + Ovsynch oestrus synchronization protocol was applied to the cows. Following the fixed time insemination (day 0), the cows were divided into 4 groups. In Group 1 (n = 42), progesterone releasing intravaginal device (PRID) was placed vaginally at 84 h and removed on the 9th day after the artificial insemination. In Group 2 (n = 40), the cows were administered human chorionic gonadotropin (hCG) on the 7th day. Group 3 (n = 45) was applied a combination of progesterone and hCG. Group 4 (n = 42) was not given any treatment. Blood samples were collected from all cows 4 times on days 3.5, 7, 12, and 18 to evaluate progesterone concentrations. The pregnancy rates were 40.47%, 37.50%, 44.44%, and 30.95% in Group 1, 2, 3, and 4, respectively (P > 0.05). In addition, in cows with progesterone concentrations <2 ng/ml on day 3.5, the pregnancy rates were found to be lower than in the cows with progesterone concentrations >2 ng/ml in Group 4 (P < 0.05). Progesterone supplementation in cows with progesterone concentrations < 2 ng/ml appeared to increase pregnancy rates (P < 0.05) in Groups 1 and 3. As a result, post-insemination hormonal applications in the repeat breeder cows did not increase the pregnancy rate. However, it was concluded that determination of progesterone concentrations on day 3.5 following artificial insemination and then hormonal support in the cows with low concentrations would increased the pregnancy rate.

scholarly journals Comparison of the effects of Presynch-Ovsynch, Presynch- Ovsynch+CIDR, and G6G protocols on the reproductive performance of lactating Holstein cows in the postpartum period

2021 ◽  
Vol 53 (4) ◽  
Author(s):  
Hesam Kohsari ◽  
Khatereh Berenjian
Keyword(s):  
Serum Concentration ◽  
Pregnancy Rate ◽  
Reproductive Performance ◽  
Body Condition Score ◽  
Dairy Farm ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Holstein Cows ◽  
Treatment Protocols ◽  
Ovulatory Follicle

This study was performed on an industrial dairy farm near Tehran province, Iran, on 666 lactating Holstein cows from September 2019 to June 2020 in order to eliminate the harmful effects of heat stress on the reproductive performance of the cows. The hypothesis of the recent study was that by increasing the serum concentration of progesterone (P4) in the luteal phase before insemination in the form of Presynch-Ovsynch+CIDR (POC) and G6G protocols, the pregnancy rate of cows would be increased compared to the Presynch-Ovsynch (PO) protocol. The aim of the present study was to evaluate the effects of Presynch-Ovsynch (PGF2α-14d- PGF2α-12d-Ovsynch (OVS: GnRH(GnRH1)- 7d-PGF2α(PG)-2d-GnRH)-18h-Fixed-time artificial insemination (FTAI), n=212), Presynch-Ovsynch+CIDR (similar to the PO protocol, plus the use of a CIDR for 7 days, from the start of the OVS+FTAI protocol to the time of PG injection, n=230), and G6G (PGF2α- 2d-GnRH-6d-OVS+FTAI, n=224) protocols on the reproductive performance and pregnancy rate of lactating Holstein cows. The average body condition score (BCS) for the cows was about 2.5 at the time of the onset of the OVS+FTAI program. The average daily milk production for cows at the time of the start of the OVS+FTAI program was 38.3 kg/day. On average, the studied cows were inseminated 86 days postpartum. Implementation of the G6G protocol in comparison to the PO and POC protocols increased the serum concentration of P4 at GnRH1 (P=0.04). The cows that received the G6G protocol had a greater number of corpuses luteum (CL) on their ovaries at PG in comparison to the cows in the PO and POC protocols (P=0.03 and P=0.05, respectively). For all treatment protocols, the pregnancy rate of cows with &gt;2 CLs on their ovaries at PG was significantly higher than for cows with ≤2 CLs on their ovaries at this time. The overall pregnancy rate for all cows studied was 42%. Separately, pregnancy rates for cows in PO, POC, and G6G protocols were calculated at 36.7%, 41.7%, and 47.3% respectively. The highest and the lowest pregnancy rates were obtained in the G6G and PO protocols, respectively (P=0.03). It can be concluded that the G6G protocol increased the pregnancy rate of cows in comparison to the PO but not to the POC protocol. This result can be attributed to the increase in serum concentration of P4 at GnRH1 and the greater number of CLs at PG following implementation of the G6G compared to the PO protocol. Although CIDR administration in the POC protocol led to an increase in the pregnancy rate of cows compared to the PO protocol, possibly by increasing the synchrony rate and the quality of the ovulatory follicle, this increase was not statistically significant (P=0.09).

The influence of purified porcine relaxin on the reproductive performance of sows following artificial insemination with fresh or frozen semen

1991 ◽  
Vol 71 (1) ◽  
pp. 237-239 ◽  
Author(s):  
P. A. Thacker ◽  
A. D. Gooneratne ◽  
R. N. Kirkwood
Keyword(s):  
Key Words ◽  
Pregnancy Rate ◽  
Litter Size ◽  
Reproductive Performance ◽  
Artificial Insemination ◽  
Pregnancy Rates ◽  
Frozen Semen

Pregnancy rates and litter sizes following insemination of sows with fresh-extended and frozen-thawed semen averaged 71 vs. 53% and 10.6 vs. 4.4, respectively, and was not affected by the addition of 12.5 μg relaxin to semen. These results indicate no relaxin mediated effect on either pregnancy rate or litter size when sows are artificially inseminated with relaxin-supplemented semen. Key words: Artificial insemination, relaxin, sows

19 FACTORS AFFECTING PREGNANCY RATE AFTER ARTIFICIAL INSEMINATION WITH EQUINE SEMEN: PRODUCTION OF THE FIRST FOAL USING FROZEN SEMEN IN KOREA

2011 ◽  
Vol 23 (1) ◽  
pp. 116
Author(s):  
Y. S. Park ◽  
Y. G. Cho ◽  
K. H. Cho ◽  
G. J. Cho
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Technology Development ◽  
Skim Milk ◽  
Development Program ◽  
Field Trials ◽  
Pregnancy Rates ◽  
Chi Square ◽  
Semen Collection ◽  
Frozen Semen

Research in the area of equine artificial insemination (AI) has led to its increased application in field trials (Loomis and Graham, 2008). However, procedures for equine semen collection, cooling and freezing of semen and artificial insemination need further improvement. This study examined the effect of semen preparation and ovulation on equine AI success. Stallion semen was collected via artificial vagina, diluted with skim-milk extender, and preserved by either cooling to 4°C or cryopreservation and storage in liquid nitrogen. Mares were examined by ultrasound for follicle development with every 12 h during oestrus. During AI, semen was inserted into uterine horn adjacent to the ovulating follicle sized over 4 cm and irregular shape. In experiment 1, mares were inseminated with either cooled, cooled-transported, or frozen–thawed semen. Cooled semen was used immediately after collection and cooling. Cooled-transported semen was used 4 h after semen collection and dilution. Semen freezing procedure was followed by Moore et al. (2006). In experiment 2, we examined the effect of buffer (skim-milk extender), which was infused into the uterus at the time of AI with frozen–thawed semen. In experiment 3, we compared AI pregnancy rates for mares ovulating spontaneously v. after treatment with hCG. Pregnancy data were analysed Chi square test where P-values < 0.05 were considered significantly different. In experiment 1, the pregnancy rates after AI using cooled, cooled-transported, and frozen–thawed semen were 60 (10/6), 50 (8/4), and 37.5% (8/3), respectively, and similar among treatments. In experiment 2, the pregnancy rate of mares infused with buffer at AI was 37.5% (8/3) which was higher than that with no buffer (0%; 6/0). In experiment 3, the pregnancy rates of mares were similar between ovulated spontaneously (25%; 8/2) and ovulated with hCG (50%; 8/4). The results suggest that equine semen that has been cooled, cooled and transported or frozen can be successfully used to establish AI pregnancy. Also, the pregnancy rates after AI can be increased by infusing buffer into the uterus at AI or by inducing ovulation with hCG. These experiments resulted in the first foal produced in Korea with frozen–thawed equine semen. This research was supported by Technology Development Program for Agriculture and Forestry, Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea.

scholarly journals 161 PREGNANCY RATES OBTAINED AFTER EMBRYO TRANSFER AT FIXED TIME OF IN VIVO-, IVF- AND CLONED-DERIVED EMBRYOS

2005 ◽  
Vol 17 (2) ◽  
pp. 231
Author(s):  
J. Lagioia ◽  
M. Panarace ◽  
M. Marfil ◽  
M. Basualdo ◽  
J. Gutierrez ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Transfer Programs ◽  
Estrus Detection ◽  
Group 2 ◽  
Low Efficiency ◽  
Group 1

The most important factor in bovine embryo transfer programs is the low efficiency in the utilization of the recipients; this low efficiency is associated with low response to synchronization protocols and failures in estrus detection. It has been shown that cows transferred at fixed time with in vivo-derived embryos resulted in high rates of recipients selected for transfer and high overall pregnancy rates (recipients pregnant/recipients treated) (Tribulo et al. 2002 Theriogenology 57, 563). An experiment was designed to evaluate the pregnancy rate in recipients transferred with in vivo (fresh and frozen), IVF, and cloned-derived embryos without estrus detection. A total of 1555 non-lactating Bos Taurus crossbred beef cows was divided into two groups. Cows from group 1 (n = 421) were synchronized with a progesterone intravaginal releasing device (1 g P4; DIB, Syntex®, Buenos Aires, Argentina) plus 2 mg of estradiol benzoate (EB) i.m. (Syntex®) on Day 0. On Day 5, they received 400 IU of eCG (Novormon 5000, Syntex®) i.m. and 150 μg of D-Cloprostenol (PGF2α) (Bioprost-D, Biotay®, Buenos Aires, Argentina). The DIB devices were removed on Day 8 and on Day 9, 1 mg of EB was injected. Day 10 was arbitrarily considered as the day of estrus. Cows from group 2 (n = 1134) received 2 doses of PGF2α 14 days apart and were checked for heat during 5 days after the second PGF2α dose. Cows of both groups were examined 7 days after estrus by ultrasonography (Pie Medical Scanner 200®) and those with a corpus luteum >10 mm of diameter were transferred nonsurgically with in vivo (fresh and frozen), IVF, and cloned-derived embryos. In group 1, 360 cows were transferred, and in group 2, 726 cows were transferred (Table 1). Pregnancy was diagnosed 23 days later by ultrasonography (Pie Medical Scanner 200®). The pregnancy rates were compared statistically between groups 1 and 2 by analysis of variance (Infostat, LSD Fisher). There was no significant statistic difference (P > 0.05) between pregnancy rate in group 1 and 2 with in vivo (fresh), IVF, and cloned-derived embryos. However, pregnancy rate of frozen in vivo-derived embryos was lower in group 1 than in group 2 (P < 0.05). Results showed that treatment using DIB combined with EB, PGF2α, and eCG associated with embryo transfer without estrus detection (group 1) had no difference in pregnancy rate when compared with the treatment where synchronization with PGF2α and heat detection were used (group 2). Another important advantage is the use the group 1 treatment for increasing the flexibility and efficiency in the management of the recipients of in vivo, IVF, and cloned-derived embryo transfer programs. Table 1. Comparison of pregnancy rates between group 1 (embryo transfer at fixed time) and group 2 (embryo transfer 7 days after estrus detection)

scholarly journals Pregnancy rates in hair sheep after Ovsynch synchronization and a combined intracervical fixed-time artificial insemination and 10-day mating period

2019 ◽  
Vol 12 (11) ◽  
pp. 1779-1783
Author(s):  
D. A. Vallejo ◽  
J. D. Londoño ◽  
Y. A. Yepes ◽  
V. Tamayo ◽  
A. F. Mejia ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Prostaglandin F2α ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Control Group ◽  
Mating Period ◽  
Mating Group ◽  
Alternative Materials ◽  
And Control

Aim: This study aimed to evaluate the pregnancy rates in hair ewes using an Ovsynch synchronization protocol under a breeding system that combines fixed-time insemination plus a 10-day mating period as an alternative. Materials and Methods: Through an experimental study (n=27), ewes were randomly located into one of three treatments: (1) Pre-synch (n=9): Prostaglandin F2α (PGF2α)+Gonadotropin-releasing hormone (GnRH)+PGF2α+GnRH; (2) Ovsynch (n=9): GnRH+PGF2α+GnRH; and (3) control: Ewes bred by natural mating (NM) (n=9). Ewes were fixed-time inseminated (fixed-time artificial insemination [FTAI]) with fresh semen, collected just before the insemination time through vaginoscopy at 16 h after the second GnRH (gonadorelin) injection. Each experimental group was placed separately during 15 days and, after this time, fertile rams were allowed back with ewes for a 10-day mating period. Control group ewes remained with the rest of the herd suitable for breeding and were bred under NM. Pregnancy diagnosis was performed by ultrasound at 28-, 56-, and 84-day post-breeding to differentiate between FTAI and NM pregnancies. Total (FTAI±NM) pregnancy rates at 56-day post-breeding were used to compared Pre-synch, Ovsynch, and control. For this purpose, two-tailed proportions comparison z-test was used with a 95% confidence level, for testing as the null hypothesis whether two proportions were equal. Results: Pregnancy rates were higher in control ewes (66.4%) than FTAI (46.6%). When pregnancy rates after a 10-day mating period (40%) were added, the final rate (86.6%) was significantly (p<0.05) higher in Ovsynch-based protocols. The pregnancy rate was significantly lower in FTAI ewes compared to FTAI +10-day mating group (p<0.05). The overall pregnancy rate was 88.0, 85.7, and 67.0 (p>0.05) for Pre-synch, Ovsynch, and control ewes, respectively. Conclusion: These results provide evidence on the benefits of combined FTAI protocols for improving the reproductive efficiency of sheep.

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

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.

22 PREGNANCY RATES IN DAIRY COWS TREATED WITH PROGESTERONE-RELEASING DEVICES AND DIFFERENT GONADOTROPIN-RELEASING HORMONE OR ESTRADIOL PLUS EQUINE CHORIONIC GONADOTROPIN FIXED-TIME ARTIFICIAL INSEMINATION PROTOCOLS

2008 ◽  
Vol 20 (1) ◽  
pp. 91 ◽  
Author(s):  
G. Veneranda ◽  
L. Filippi ◽  
D. Racca ◽  
L. Cutaia ◽  
G. A. Bo
Keyword(s):  
Dairy Cows ◽  
Pregnancy Rate ◽  
Milk Yield ◽  
Artificial Insemination ◽  
Fixed Time ◽  
Gonadotropin Releasing Hormone ◽  
Pregnancy Rates ◽  
Device Removal ◽  
Treatment Groups ◽  
Lactating Dairy Cows

We have previously shown that the addition of eCG improved pregnancy rates following fixed-time artificial insemination (FTAI) in lactating dairy cows treated with estradiol benzoate (EB) and progesterone releasing devices (Veneranda et al. 2006 Reprod. Fertil. Dev. 18, 118). An experiment was designed to compare pregnancy rates in lactating dairy cows treated with progesterone-releasing devices and EB plus eCG with different gonadotropin-releasing hormone (GnRH)-based protocols. Five-hundred lactating dairy cows between 30 and 51 days postpartum (when prostaglandin F (PGF) treatments were given in the Pre-Synch groups), with a milk yield of 29.5 � 7.0 kg per day (range 13.0 to 46.0 kg) and a body condition score (BCS) between 2.5 to 3.5 out of 5 were used. Cows were blocked by days postpartum and randomly assigned to five treatment groups. Cows in the Pre-Synch group received PGF 28 and 14 days prior to the insertion of a DIB device (1 g progesterone, Syntex SA, Buenos Aires, Argentina) and the administration of 50 µg of Lecirelin (GnRH, Ovusin, Syntex SA) IM (Day 0). On Day 7, DIB were removed and cows received PGF (0.5 mg cloprostenol, Ciclase, Syntex SA). On Day 9, cows received a second GnRH treatment and were FTAI 16 h later (60 h after device removal). Cows in the Modified Pre-Synch group were treated similarly except that they received a DIB for 7 days prior to the second PGF injection and no DIB at the time of the first GnRH. Cows in the P4-Synch group were treated as those in the Pre-synch group but did not receive the two doses of PGF 28 and 14 days earlier. Cows in the P4 + EB + eCG groups received a DIB for 8 days, 2 mg of EB at DIB insertion (Day 0), and PGF and 400 IU eCG (Novormon, Syntex SA) IM at DIB removal (Day 8); they were subdivided to receive 1 mg of EB on Day 9 (P4 + EB + eCG + EB group) or GnRH on Day 10 (P4 + EB + eCG + GnRH group). Cows in these latter two groups were also FTAI 60 h after device removal. Pregnancy was determined by rectal palpation 50 days after FTAI and data were analyzed by logistic regression. Pregnancy rates were not affected by BCS, days postpartum, or milk yield (P > 0.5). However, there was a significant group effect due to a higher (P < 0.05) pregnancy rate in the P4 + EB + eCG + EB (49%) and P4 + EB + eCG + GnRH (44%) treatment groups than in those in the Modified Pre-Synch group (30%). Pregnancy rate in the P4-Synch group (39%) was lower (P < 0.05) than those in the P4 + EB + eCG + EB group but not different from the others. Finally, pregnancy rate in Pre-Synch group (41%) was intermediate and not different from the other treatment groups. Results of these experiments suggest that treatments with progesterone-releasing devices, EB, and eCG result in pregnancy rates that are comparable to or better than those obtained in GnRH-based protocols in lactating dairy cows. Further studies are needed to investigate whether eCG could increase pregnancy rates in cows treated with GnRH and progesterone-releasing devices. The authors thank Syntex SA for providing the hormones used in the study.

scholarly journals The effect of clitoral stimulation post artificial insemination on pregnancy rates of multiparous Bos indicus beef cows submitted to estradiol/progesterone-based estrus synchronization protocol

2020 ◽  
Vol 98 (7) ◽  
Author(s):  
Ramiro V Oliveira Filho ◽  
Reinaldo F Cooke ◽  
Gustavo A de Mello ◽  
Victor M Pereira ◽  
Jose Luiz M Vasconcelos ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Estrus Synchronization ◽  
Exit Velocity ◽  
Clitoral Stimulation

Abstract Clitoral stimulation after artificial insemination (AI) in beef cattle is a common practice utilized by AI technicians; however, the effect of clitoral stimulation during fixed-time AI (TAI) is still unknown. The objective of the present experiment was to evaluate the effect of clitoral stimulation on temperament responses and pregnancy rates to TAI in Bos indicus beef cows. A total of 1,186 multiparous Nellore cows across three different locations were assigned to an estradiol/progesterone-based estrus synchronization + TAI protocol (day −11 to 0). Cows were randomly assigned to receive either 3 s of clitoral stimulation (n = 602) or no clitoral stimulation (n = 584) immediately after TAI (day 0). Cow body condition score (BCS) was recorded on day −11. Estrus expression was evaluated based on estrus detection visual aid patch activation on day 0 (estrus, ≥50% activated; no estrus, &lt;50% activated). Temperament was assessed by individual chute score based on a 5-point scale before TAI, and individual exit velocity was measured after clitoral stimulation. Pregnancy diagnosis was performed 30 d after TAI via transrectal ultrasonography. Pregnancy rate to TAI was positively affected by BCS (P &lt; 0.01) and estrus expression (P = 0.03). Pregnancy rates of cows receiving clitoral stimulation did not differ (P = 0.39) from cows non-stimulated (47.5 ± 4.6% vs. 44.3 ± 4.6%, respectively). No interaction of clitoral stimulation and estrus expression was observed (P = 0.26). Chute score was positively correlated to exit velocity (P &lt; 0.01; r = 0.29); however, clitoral stimulation did not affect exit velocity (P = 0.86). In summary, pregnancy rates to TAI are influenced by various factors and multiple strategies have the potential to increase the fertility of beef cows submitted to TAI; however, clitoral stimulation of Bos indicus beef cows did not improve TAI pregnancy rate.

scholarly journals A retrospective analysis of bull:cow ratio effects on pregnancy rates of beef cows previously enrolled in fixed-time artificial insemination protocols

2021 ◽  
Author(s):  
Claire L Timlin ◽  
Nicholas W Dias ◽  
Laura Hungerford ◽  
Tracey Redifer ◽  
John F Currin ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Artificial Insemination ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Economic Feasibility ◽  
Virginia Department ◽  
Breeding Soundness ◽  
Breeding Seasons ◽  
Natural Service

Abstract This retrospective study aimed to determine if the number of cows exposed per bull affects pregnancy rates of cows returning to estrus after fixed-time artificial insemination (FTAI). Data were compiled over the course of 13 breeding seasons (6 fall and 7 spring seasons) between 2010 and 2017 from the Virginia Department of Corrections herd. Available records contained data from 17 farms and 324 groups of cows (average 47 cows/group). Multiparous cows and heifers (average age per group: 5.11 ± 0.14 years; n = 14,868) were exposed to FTAI. After FTAI, animals were placed on pasture with bulls diagnosed as fertile by a breeding soundness exam for natural service of cows who did not become pregnant to FTAI (n = 7,248; average 22 cows/group). Animals were classified as pregnant to FTAI, to natural service on first return to estrus, or to natural service on second or subsequent estrus determined by fetal aging at pregnancy diagnosis. The bull:cow ratio for the total number of cows exposed ranged from 1:9 to 1:73 with an average of 1:31. The bull:cow ratio considering only open cows exposed after FTAI ranged from 1:2 to 1:44 with an average of 1:14. There was significant negative, small correlation between the bull:cow ratio for total number of cows exposed and return to estrus pregnancy rate in fall breeding seasons (P = 0.01, r 2 = 0.04) but not in spring (P = 0.90). There was a significant negative, small correlation between bull:cow ratio of open cows exposed and pregnancy rates to first return to estrus in fall herds with a single sire (P &lt; 0.001, r 2 = 0.11). There was no correlation in fall herds using multiple sires or spring herds (P ≥ 0.12). Bull:cow ratio accounted for only 1 – 11% of variation in the pregnancy rates, thus we conclude that a decreased bull:cow ratio (up to 1:73) did not affect natural service return to estrus pregnancy rate. Cattlemen may consider a reduced number of bulls needed for natural service breeding after FTAI, which can decrease bull related costs and increase the economic feasibility of adopting FTAI protocols.

Sign in / Sign up

Export Citation Format

Share Document