Progress 10/01/02 to 09/30/07
Outputs
OUTPUTS: Two studies were conducted this past year. In the first experiment 25 cows were synchronized with the CO-Synch + CIDR protocol at the University of Illinois Orr Beef Center (Baylis, IL). Although cows received all synchronization treatments, including the second injection of GnRH, cows were not inseminated (by design). They were administered a previously used CIDR 14 days after the second injection of GnRH. The CIDR was removed 6 days later (20 days after the second injection of GnRH). HeatWatch patches were applied to all cows and they were monitored for estrus behavior for the next 22 days. Cows were also monitored for estrus visually (independent of the HeatWatch results). Based on visual estrus detection 84% of the cows were detected in estrus during the first six days after the CIDR removal (76% during the first three days after the CIDR removal). The cows not detected in estrus fell into three categories: non-detected estrus (HeatWatch detected only; 3 cows), delayed
estrus (2 cows; HeatWatch detected on days 9-10), and silent estrus (no estrus detected until 21-22 days after CIDR removal; 2 cows). The second study was conducted on 127 cows at the University of Illinois Beef Herd in Baylis, IL (Orr Beef Center). The cows were synchronized as in the first study and they were bred (TAI; approximately 56 hours after PGF treatment) at the time of the second injection of GnRH. All cows were administered a previously used CIDR on day 14 after the second injection of GnRH. One-half of the cows also received an injection of GnRH (100 mcg) at the time of CIDR insertion. HeatWatch monitors were affixed to all cows and they were monitored for estrus behavior for the first six days after CIDR removal. The CIDR was left in situ for six days as in the first study and as was done last year. Pregnancy status was determined via ultrasonography approximately 65 days after the TAI. Only 73% of the cows not conceiving to the TAI were detected in estrus during the
first six days after CIDR removal. Return estrus were synchronized (74% of the cows exhibiting estrus were in estrus the first two days after CIDR removal). Inclusion of GnRH had no affect on improving synchrony or on improving the establishment of pregnancy.
PARTICIPANTS: Darrel J. Kesler, Ph.D. is the principal investigator. Dr. Kesler designed the studies, oversaw the implementation of the studies, and summarized the data analysis and results.
TARGET AUDIENCES: Results from these studies provide valuable information to beef producers throughout the U.S. Data were not only disseminated to researchers, but to livestock producers and to graduate and undergraduate students.
Impacts
Three accomplishments were made during the past year: 1) Once-used CIDRs administered 14-20 days after the initial insemination synchronize the return estrus without compromising the conception rate. 2) Inclusion of GnRH at the administration of the resynch CIDR had no effect on synchrony or on the establishment of pregnancy. 3) Non-pregnant cows with not detected estrus were a result of non-detection, delayed estrus, and silent estrus.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
Two experiments were conducted. Experiment 1 was conducted at the Orr Beef Research Center in Baylis, IL. A total of 252 were included in the experiment. All cows were synchronized with the CO-Synch + CIDR protocol. Cows were inseminated at a predetermined time of 54 hours after the PGF injection and CIDR removal. Cows were then randomly assigned to one of two groups. Cows in the control group received no further treatment. Cows in the CIDR-treated group were administered a once-used CIDR 14 days after the initial timed AI. The CIDR was left in situ for six days and removed 20 days after the initial timed AI. All cows were observed for estrus and inseminated at estrus 18 to 24 days after the initial AI. Pregnancy rates to the initial AI were not different (averaged 40%). Conception rates to the return estrus were 47% and 59% for control and CIDR-treated cows, respectively. Return estrus rates averaged 41%; however, return estrus for the CIDR-treated cows were more
(P<.05) synchronized (97% of the cows that exhibited estrus were in estrus in a two day period). Cumulative pregnancy rates (1st and 2nd AI) did not differ and averaged 53%. Experiment 2 was conducted at the Dixon Spring Agriculture Center in Simpson, Illinois. A total of 471 beef cows suckling calves were included in this study. All cows were synchronized with the CO-Synch + CIDR protocol. Cows were inseminated at a predetermined time of 54 hours after the PGF injection and CIDR removal. Cows were then randomly assigned to one of two groups. Cows in the GnRH-treated group were administered an injection of GnRH (100 mcg) 12 days after the initial AI while cows in the CIDR-treated group were administered a once used CIDR on 14 days after the initial AI. The CIDR was left in situ for six days and removed 20 days after the initial timed AI. All cows were observed for estrus and inseminated at estrus 18 to 24 days after the initial AI. Pregnancy rates to the initial AI were not different
(averaged 53%). Conception rates to the return estrus were 66% and 60% for GnRH-treated and CIDR-treated cows, respectively (P>.10). Return estrus rates averaged 62%; however, return estrus for the CIDR-treated cows were more (P<.01) synchronized. Cumulative pregnancy rates (1st and 2nd AI) did not differ and averaged 72%. Previous studies have demonstrated that the administration of a CIDR through day 21 negatively affected the return estrus conception rate. These data demonstrate that use of a once-used CIDR through day 20 synchronized the return estrus without affecting (or with minimum affect) on the return estrus conception rate. This agrees with data published by Colazo et al. (Theriogenology 65:557-572; 2006) where once-used CIDRs were administered to heifers. In that study conception rates were 64% and 62% for CIDR-treated and control heifers, respectively, and the CIDR improved synchrony of the return estrus.
Impacts
These data suggest that a once-used CIDR may be used for resynchronization without compromising the conception rate. This would permit producers to increase use of AI and reduce the number of clean-up bulls needed allowing for increased profits and improved quality of life.
Publications
- Larson, J.E., Lamb, G.C., Stevenson, J.S., Johnson, S.K., Day, M.L., Geary, T.W., Kesler, D.J., DeJarnette, J.M., Schrick, F.N., DiCostanzo, A. and Arseneau, J.D. 2006. Synchronization of estrus in suckled beef cows for detected estrus and artificial insemination and time artificial insemination using gonadogropin-releasing hormone, prostaglandin, and progesterone. J. Anim. Sci. 84:332-342.
- Stevenson, J.S., Pursley, J.R., Garverick, H.A., Fricke, P.M., Kesler, D.J., Ottobre, J.S. and Wiltbank, M.C. 2006. Treatment of cycling and noncycling lactating dairy cows with progesterone during ovsynch. J. Dairy Sci. 89:2567-2578.
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Progress 01/01/05 to 12/31/05
Outputs
The purpose of these studies was to determine if the addition of a resynchronization CIDR in the CO-Synch+CIDR protocol would improve the expression of estrus and return estrus pregnancy rates in cows not conceiving to the initial timed-AI (TAI). Two trials were performed using crossbred Angus and Simmental cows. All cows in both trials were synchronized using the CO-Synch+CIDR protocol and a fixed TAI. The ReSynch group received a resynchronization CIDR during days 14-21 after the TAI. The Control group was not administered a resynchronization CIDR. In trial two, cows (n=155) were administered the same treatment as the trial one ReSynch group. Post-AI CIDR treatment did not affect initial ReSynch pregnancy rates, which averaged 66%. Second service pregnancy rates tended (P=.07) to be higher than controls at 62%. Cumulative pregnancy rates and return estrus were similar to controls. While further research is necessary, these results exhibit feasibility of the CIDR as
a resynchronization tool. Another study was conducted to evaluate the utility of the combined use of estrous synchronization, sex-sorted semen, in vitro fertilization, and embryo transfer technologies. The study included 486 postpartum suckled beef cows. Holstein oocytes collected from slaughterhouse ovaries were fertilized in vitro with frozen-thawed semen that had been sex sorted to produce female offspring. The beef cows had been synchronized with the CO-Synch protocol (GnRH followed seven days later with PGF and a second injection of GnRH two days later) including or not including a CIDR (inserted at GnRH treatment and removed at PGF treatment). Two days after PGF all cows received an injection of GnRH. One or two blastocysts were transferred into the cows seven days after the second GnRH treatment if the cows had luteal tissue. Single embryos were placed in the uterine horn ipsilateral to the ovary with the CL whereas for twins one embryo was placed in each uterine horn.
Pregnancy was diagnosed 40-55 days post-transfer via ultrasonography. Luteal tissue was detected per rectum in 463 cows (95%). Pregnancy rates were not affected (P>.10) by inclusion of the CIDR; however, pregnancy rate was higher (P<.01) in cows receiving two embryos (51%) vs. one embryo (38%). Sex of calf was assessed at calving and 90% (158/176) of the calves were heifers. Twenty-two percent of the cows with twin transfers calved with twins. There tended (P=.06) to be a higher pregnancy loss in cows with twin transfers (31%) than in cows with single transfers (19%). Inclusion of CIDR in the synchronization did not affect (P>.10) pregnancy loss. Calving rate was not affected by inclusion of the CIDR; however, calving rate was higher (P<.01) in cows receiving twins (46/100) vs. one embryo (30/100). Eight of the cows were diagnosed with hydramnios/hydrallantois and were not affected by CIDR inclusion nor number of embryos transferred. Calving difficulty was no greater than in previous
years even though the Holstein calves were larger than beef calves and even though a large number of cows gave birth to twins. No excessive large calves were observed.
Impacts
These data demonstrate the utility of resynchronization--synchronizing the return estrus for AI--and the utility of combined use of estrous synchronization, sex-sorted semen, in vitro fertilization, and embryo transfer technologies. The stacking of this technology is an efficacious method to improve pregnancy rates and increase to number of calves of desired sex.
Publications
- Kesler, D.J. 2005. Estrus synchronization systems--GnRH. Applied Reproductive Strategies in Beef Cattle. Proc. Applied Reproductive Strategies in Beef Cattle Symp., Reno, NV, pp. 35-46.
- Kesler, D.J. 2005. Estrus synchronization systems--GnRH. Applied Reproductive Strategies in Beef Cattle. Proc. Applied Reproductive Strategies in Beef Cattle Symp., Lexington, KY, pp. 40-52.
- Kesler, D.J. 2005. Estrus synchronization systems--GnRH. Applied Reproductive Strategies in Beef Cattle. Proc. Applied Reproductive Strategies in Beef Cattle Symp., College Station, TX, pp. 43-55.
- Kesler, D.J. 2005. Reproductive technologies: Technology stacking. Proc. Applied Reproductive Strategies in Beef Cattle Symp., College Station, TX, pp. 315-319.
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Progress 01/01/04 to 12/31/04
Outputs
Two studies were conducted on resynchronization-synchronization of the return estrus in females not conceiving to the first synchronized AI. A total of 83 heifers and 233 cows were included in two studies. Females were administered a CIDR 5 to 14, 14-21, or 5-21 days after a timed AI or received no treatment and served as controls. Post-AI treatment had no effect on the first service pregnancy rates in heifers (68%)or cows (56%). Non-pregnant females treated with a CIDR that was left in situ until day 21 had a more uniform return to estrus; however, second service pregnancy rates were compromised in cows (71% vs. 48%). This effect was not observed in heifers as second service pregnancy rates were 60% for both control and treated heifers. In summary, resynchronization with the CIDR synchronizes the return estrus, but is not a value reproductive tool when used alone as pregnancy rates were compromised.
Impacts
Resynchronization with the CIDR alone is not a valuable reproductive tool. Although it synchronizes the return estrus in non-pregnant cows, second service pregnancy rates are compromised. Further research is needed to develop a resynchronization protocol.
Publications
- Bremer, V.R., Damiana, S.M., Ireland, F.A., Faulkner, D.B. and Kesler, D.J. 2004. Optimizing the interval from PGF to timed AI in CoSynch+CIDR and 7-11 Synch estrus synchronization protocols for postpartum beef cows. J. Anim. Sci. 82(Suppl. 2):106.
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Progress 01/01/03 to 12/31/03
Outputs
An experiment was conducted to determine the optimal, yet practical, time to breed cows synchronized with CoSynch+CIDR and 7-11 Synch protocols. Two fall breeding herds of Angus x Simmental suckled beef cows managed at the University of Illinois Dixon Springs Agriculture Center in Simpson, Illinois were each assigned to one of the two synchronization procedure experiments. The interval from PGF to time AI (TAI) was the main effect in both experiments. The cows in experiment 1 were synchronized with the CoSynch+CIDR protocol. All cows (n = 226) were administered an injection of GnRH at the same time as CIDR insertion. Seven days later the CIDR was removed and cows were administered PGF. Cows were inseminated at predetermined times (48, 54, and 66 hours post PGF) using semen from commercial bull studs and concurrently administered GnRH. All cows in experiment 2 were synchronized with the 7-11 Synch protocol. All cows (n = 318) were fed 0.5 mg of MGA/head/day for seven
days. The MGA was fed each morning at the same time with ground corn at a rate of 0.45 kg/head/day. On the seventh day of MGA feeding all cows were administered an injection of PGF. Four days after the injection of PGF cows were administered GnRH followed by an injection of PGF seven days later. Cows of the 7-11 Synch experiment were randomly assigned to one of the same three time intervals from PGF of TAI as the CoSynch+CIDR experiment. Bulls for subsequent breeding were included with the cows 10 days after completion of TAIs. Cows were examined for pregnancy via ultrasonography 32 to 37 days after the TAI. The synchronized pregnancy rates for cows inseminated 54 and 66 hours after PGF were greater (P<.05) than cows inseminated at 48 hours in the CoSynch+CIDR experiment. Synchronized pregnancy rates for cows with CoSynch+CIDR were 59%, 74%, and 74% when TAI at 48, 54, and 66 hours, respectively. Synchronized pregnancy rates for cows with 7-11 Synch were 59%, 52%, and 63% when
inseminated at 48, 54, and 66 hours, respectively; however, pregnancy rates were not affected (P>.05) by time of insemination. The 48 day breeding season pregnancy rates were determined 110 days post TAI via transrectal palpation. Time of AI did not affect (P>.05) the 48 day breeding season pregnancy rates and averaged 87% across all times in both experiments. In summary, both CoSynch+CIDR and 7-11 Synch have relatively long intervals of time from PGF to TAI without compromising fertility; however, delaying from 48 h to 54-66 h improved synchronized pregnancy rates in cow synchronized with the CoSynch+CIDR protocol.
Impacts
A popular estrus synchronization protocol for beef cows, CoSynch, has been modified to include the CIDR. Inclusion of the CIDR improves pregnancy rates; however, the proper time to AI after the injection of PGF had not been evaluated. These data demonstrate that higher pregnancy rates will be obtained if the interval is extended from 48 hours to 54-66 hours. This resulted in 15 more calves per 100 cows treated for synchronization which will have a huge impact on profitability.
Publications
- Kesler, D.J. 2003. Synchronization of estrus in heifers. Prof. Anim. Sci. 19:96-108.
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