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Evaluation Of Long Term Cidr Based Estrus Synchronization Protocols In Primiparous Two Year Old Beef Cows
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Book Synopsis Evaluation of Long-term CIDR-based Estrus Synchronization Protocols in Primiparous Two-year-old Beef Cows by : Jillian Mae Abel
Download or read book Evaluation of Long-term CIDR-based Estrus Synchronization Protocols in Primiparous Two-year-old Beef Cows written by Jillian Mae Abel and published by . This book was released on 2015 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development and comparison of strategies designed to enhance reproductive management of primiparous two-year-old beef cows coincide with the recent increase in heifer retention and the significant number of younger age females that are now entering the U.S. cow herd. Reproductive management of primiparous two-year-old cows presents a unique challenge in managing a beef herd, since this age group of females typically experiences the highest incidence of reproductive failure. Strategic management of replacement beef heifers and primiparous cows is necessary to ensure their continued long-term reproductive success, which provides the opportunity for beef producers to increase retention rates, reduce input costs, and ultimately enhance production efficiency. Estrus synchronization and artificial insemination (AI) are important management tools available to producers that facilitate genetic improvement and enhance reproductive efficiency. A list of recommended protocols may be used to facilitate fixed-time AI (FTAI) in beef cows and heifers, and we now know that specific protocols perform better among various age classes of females. Short-term controlled internal drug release (CIDR)-based protocols are currently the preferred method to synchronize estrus prior to FTAI in postpartum beef cows. Alternatively, long-term CIDR-based protocols have been used with greater success in beef heifers. Progestin-based estrus synchronization protocols offer the potential to induce estrous cyclicity in anestrous postpartum cows and advance conception date. Experiment 1 was designed to compare the 14-d CIDR-PG (14-d) and 7-d CO-Synch + CIDR (7-d) protocols on the basis of estrous response, pregnancy rates after fixed-time AI (FTAI), and final pregnancy in primiparous two-year-old cows. Cows assigned to 14-d (n = 355) received a CIDR insert on Day 0 with removal on Day 14. Cows assigned to 7-d (n = 349) received GnRH and CIDR inserts on Day 23. On Day 30 CIDRs were removed from 7-d cows and PGF2[alpha] was administered to all cows in each treatment. On Day 33, 66 and 72 h after PGF2[alpha], GnRH was administered concurrent with FTAI. Estrous response at FTAI was higher for 7-d compared to 14-d cows (74% vs 43%, respectively; P
Book Synopsis Comparison of CIDR-based Protocols to Synchronize Estrus in Beef Heifers by : Nicole Renee Leitman
Download or read book Comparison of CIDR-based Protocols to Synchronize Estrus in Beef Heifers written by Nicole Renee Leitman and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrus synchronization and artificial insemination (AI) are reproductive management techniques that allow beef producers to enhance the reproductive efficiency and genetic composition of their cow herd. However, U.S. beef producers have been reluctant to adopt these reproductive management tools, largely due to time and labor. Recent research to synchronize estrus, therefore, has focused on the development of estrus synchronization protocols that facilitate fixed-time AI (FTAI). Although protocols have been developed that allow the successful use of FTAI in beef cows, the same degree of success in beef heifers has not been realized. Additionally, no published research has focused on characterizing the physiological responses to long- and short-term CIDR-based protocols in beef heifers. Experiment 1 evaluated ovulatory response to GnRH and synchrony of estrus and ovulation after PGF2[alpha] (PG) in beef heifers. The CIDR Select and Select Synch + CIDR protocols were evaluated among estrous cycling and prepubertal beef heifers and the CIDR-PG and Select Synch protocols were evaluated among estrous cycling beef heifers. A reduced variance for the intervals to estrus and ovulation was detected for estrous cycling heifers treated with the CIDR Select protocol in comparison to the other 3 treatments. The combined results of the estrous cycling and prepubertal heifers revealed an increased ovulatory response to GnRH for heifers treated with the CIDR Select protocol compared to the Select Synch + CIDR protocol, which ultimately resulted in a reduced variance for interval to estrus and ovulation after PG. Furthermore, no differences within treatment were detected in the variance for interval to estrus or ovulation among estrous cycling and prepubertal heifers treated with the CIDR Select protocol. These results suggest that the CIDR Select protocol may facilitate FTAI more effectively in mixed groups of estrous cycling and prepubertal beef heifers. Experiments 2 and 3 evaluated modifications to the CIDR Select protocol. Estrous cycling beef heifers were used in Exp. 2. The hypothesis tested was that reducing the interval from CIDR removal to GnRH administration by 2 d would facilitate an improvement in the synchrony of estrus after PG. Although a larger number of heifers that were assigned to the 28 d protocol were on d 5 and 6 at the time GnRH was administered, response to GnRH was not improved and synchrony of estrus was not enhanced following PG. In Exp. 3, a second modification to the CIDR Select protocol was evaluated using estrous cycling and prepubertal beef heifers. The hypotheses tested were: 1) reducing the interval from CIDR removal to GnRH may facilitate an improvement in the synchrony of estrus after PG, and 2) the addition of GnRH following CIDR removal is required to improve the synchrony of estrus after PG. Although no difference in estrous response was detected, mean intervals to estrus and variance for interval to estrus differed based on the interaction of treatment length, GnRH, and estrous cyclicity status. The results from Exp. 3 clearly suggest that further evaluation of long-term CIDR-based protocols is required.
Book Synopsis Comparison of Long-term CIDR-based Protocols to Synchronize Estrus in Postpartum Beef Cows by : Justin Michael Nash
Download or read book Comparison of Long-term CIDR-based Protocols to Synchronize Estrus in Postpartum Beef Cows written by Justin Michael Nash and published by . This book was released on 2011 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrus synchronization and artificial insemination are two of the most important management practices available to producers to increase reproductive performance in a beef cow-calf operation. Unfortunately, a small number of producers utilize these practices due to increased labor requirements. The use of fixed-time artificial insemination (FTAI) reduces the amount of time and labor required to detect estrus, leading to decreased input requirements. The following experiments were performed in order to compare the use of long-term controlled internal drug release (CIDR) insert-based estrus synchronization protocols prior to FTAI in estrous-cycling and anestrous postpartum beef cows. In experiments 1 and 2, two long-term CIDR-based estrus synchronization protocols were compared on the basis of physiological characteristics, including serum steroid hormone concentrations, estrous response, and follicular dynamics, as well as pregnancy rates resulting from FTAI. From these intensive trials, it was determined that both protocols yielded comparable pregnancy rates and similar physiological responses when used in postpartum beef cows. In experiment 3, the use of either a long- or short-term CIDR-based estrus synchronization protocol was compared prior to FTAI in a large-scale field trial. Results indicated that pregnancy rate resulting from FTAI was similar for both protocols. These data provide preliminary support for the use of long-term CIDR-based estrus synchronization protocols prior to FTAI in postpartum beef cows.
Book Synopsis Comparison of Long-term Progestin-based Protocols to Synchronize Estrus in Beef Heifers by : Daniel A. Mallory
Download or read book Comparison of Long-term Progestin-based Protocols to Synchronize Estrus in Beef Heifers written by Daniel A. Mallory and published by . This book was released on 2009 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiment 1 evaluated two long-term progestin-based and controlled internal drug release estrus synchronization protocols to determine their potential to facilitate fixed-time artificial insemination in estrous cycling and prepubertal beef heifers. Conception to AI, AI pregnancy, and final pregnancy rates did not differ between treatments. Experiment 2 compared two long-term progestin-based estrus synchronization protocols to evaluate their potential to facilitate fixed-time artificial insemination in estrous cycling and prepubertal beef heifers. Estrous response after PG was greater among CIDR treated heifers compared to MGA treated heifers. Conception to AI, AI pregnancy, and final pregnancy rates did not differ between treatments. In summary, the long-term CIDR protocol compared favorably with the MGA protocol. Experiment 3 was conducted to compare pregnancy rates resulting from fixed-time AI after administration of either one of two long-term CIDR-based protocols. CIDR-GnRH-PG and CIDR-PG treated heifers were fixed-time inseminated at 72 or 66 hr after PG, respectively. Fixed-time AI pregnancy rates tended to be higher among CIDR-PG compared to CIDR-GnRH-PG treated heifers. Final pregnancy rates did not differ between treatments. In summary, both long-term progestin-based protocols were effective in synchronizing estrus prior to fixed-time AI in beef heifers.
Book Synopsis Comparison of Long-term CIDR-based Protocols to Synchronize Estrus and Ovulation Prior to Fixed-time Artificial Insemination in Postpartum Beef Cows by : Neal Timothy Martin
Download or read book Comparison of Long-term CIDR-based Protocols to Synchronize Estrus and Ovulation Prior to Fixed-time Artificial Insemination in Postpartum Beef Cows written by Neal Timothy Martin and published by . This book was released on 2012 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Comparison of Controlled Internal Drug Release (CIDR)-based Protocols to Synchronize Estrus and Facilitate Artificial Insemination (AI) in Postpartum Beef Cows by : Dallas James Wilson
Download or read book Comparison of Controlled Internal Drug Release (CIDR)-based Protocols to Synchronize Estrus and Facilitate Artificial Insemination (AI) in Postpartum Beef Cows written by Dallas James Wilson and published by . This book was released on 2008 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: Artificial insemination (AI) and estrous synchronization are reproductive technologies that enable beef producers to efficiently improve herd genetics. The recent development of protocols designed to synchronize estrus and ovulation enable producers to utilize fixed-time AI (FTAI), thus reducing time and labor required to detect estrus. The 7-d Select Synch and CO-Synch + CIDR protocols provide an efficient and effective means to synchronize estrus in postpartum beef cows. Recently a 5-d Select Synch and CO-Synch + CIDR protocol was developed. To date, however, the literature is devoid of information comparing the 7-d and 5-d protocols on the basis of their practical application in the field. Experiment 1 was designed to fully characterize and compare the 7-d and 5-d Select Synch + CIDR protocols. There were no differences between treatments for estrous response, interval to estrus, or the variance for interval to estrus. Additionally, response to GnRH and follicle size at GnRH did not differ between the two treatments, nor were there any differences in synchronized conception or pregnancy rates resulting from AI. Experiment 2 was designed to compare pregnancy rates resulting from fixed-time AI following administration of the 7-d and 5-d CO-Synch + CIDR protocols with FTAI at 66 and72 h. There was no effect of treatment, technician, sire, or location on FTAI pregnancy rates. The results from these experiments indicate that the 7-d and 5-d Select Synch and CO-Synch + CIDR protocols performed comparably on the basis of synchronizing estrus and facilitating pregnancy resulting from FTAI, respectively.
Book Synopsis Comparison of Short-term Vs. Long-term Estrous Synchronization Protocols Using CIDR Devices in Sheep and Goats During and Outside the Natural Breeding Season by : Audra Whitney Harl
Download or read book Comparison of Short-term Vs. Long-term Estrous Synchronization Protocols Using CIDR Devices in Sheep and Goats During and Outside the Natural Breeding Season written by Audra Whitney Harl and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Controlling reproductive cycles during active cyclicity and seasonal anestrous in small ruminants is critical for profitability. The objective of this study was to evaluate the effect on estrous response and interval to estrus of two CIDR protocols in sheep and goats during breeding and non-breeding seasons. In experiment 1, 133 ewes were randomly assigned to 1 of 3 treatments during the breeding season. In the CIDR-7 group, ewes received a CIDR insert for 7 d. In the CIDR-7 + PGF treatment, ewes received a CIDR insert for 7 d and 20 mg of prostaglandin-F2[subscript] [alpha] (PGF2[subscript] [alpha]) upon CIDR removal. Ewes in the CIDR-14 treatment received a CIDR insert for 14 d. Following CIDR removal all ewes were exposed to a ram every 12 h until breeding. There was a shorter interval from CIDR removal to estrus in the CIDR-14 treatment compared to the CIDR-7 and CIDR-7 + PGF treatments (P
Book Synopsis A Comparison of Co-Synch + CIDR and ECP + CIDR as Estrus Synchronization Techniques for Timed Artificial Insemination of Beef Heifers by : Morgan J. Roberts
Download or read book A Comparison of Co-Synch + CIDR and ECP + CIDR as Estrus Synchronization Techniques for Timed Artificial Insemination of Beef Heifers written by Morgan J. Roberts and published by . This book was released on 2010 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study was conducted as an estrus synchronization technique comparison. The objective of this study was to compare the effectiveness of two different estrus synchronization protocols for use in beef heifers. Two CIDR based protocols were utilized in this study, Co-Synch + CIDR (progesterone, gonadotrophin releasing hormone, and prostaglandin) and ECP + CIDR (Estradiol Cypionate, progesterone, prostaglandin, and gonadotrophin releasing hormone). 65 heifers were located on the same farm, however, were separated into three groups for handling ease (Group 1=21, Group 2-23, and Group 3=21). 42 heifers (Group 1=21, Group 2=11, and Group 3=10 were synchronized using the Co-Synch + CIDR technique. Heifers were administered a 2.0 ml injection of GnRH at the time of CIDR insertion. The CIDR implants remained in the heifers for 7 days. A 5.0 ml injection of PGF was administered at the time of CIDR removal. Removal was followed by TAI 52 hours later. At the time of AI heifers received another injection of GnRH. 23 heifers (Group 2=12 and Group 3=11) received the ECP + CIDR protocol. Each heifer received a 0.5 ml injection of ECP at time of CIDR insertion. CIDR remained in heifers for 7 days. All heifers were administered a 5.0 ml shot of PGF at time of CIDR removal. 52 hours after removal, heifers were TAI and were given an injection of GnRH. Conception rates of 57.1%, 18.2 % and 60.0% were achieved with the Co-Synch + CIDR protocol after time artificial insemination. ECP + CIDR resulted in conception rates of 33.3% and 90.9% after timed artificial insemination.
Book Synopsis Comparison of Progestin Based Protocols to Synchronize Estrus and Ovulation in Beef Cows by : Daniel Joseph Schafer
Download or read book Comparison of Progestin Based Protocols to Synchronize Estrus and Ovulation in Beef Cows written by Daniel Joseph Schafer and published by . This book was released on 2005 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Management Practices to Optimize Reproductive Efficiency in Primiparous and Multiparous Suckled Beef Cows by : Jonathan F. Bader
Download or read book Management Practices to Optimize Reproductive Efficiency in Primiparous and Multiparous Suckled Beef Cows written by Jonathan F. Bader and published by . This book was released on 2003 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous work from our laboratory suggests that prepartum supplementation with whole soybeans (WSB) improves first service conception rate without affecting body condition score or estrous cyclicity status prior to initiation of estrus synchronization protocols in postpartum beef cows. The objective of the first experiment was to examine the effects of prepartum lipid supplementation to superstimulated multiparous suckled beef cows and subsequent results on embryo quantity and quality. There was no difference between treatments in quantity or quality of embryos recovered. These findings suggest that prepartum supplementation of WSB to superstimulated multiparous suckled beef cows does not affect the quantity and quality of embryos recovered. Our research has also focused on estrus synchronization and facilitating the use of fixed-time artificial insemination (AI) in beef cows. The second experiment was designed to compare pregnancy rates of postpartum beef cows resulting from fixed-time AI and after synchronization of estrus with either the 7-11 Synch or MGA ® Select protocols. The results from this experiment indicate that estrus synchronization with 7-11 Synch or MGA ® followed by fixed-timed AI (GnRH at AI) result in comparable pregnancy rates in postpartum beef cows. Both protocols may be effectively utilized by producers for fixed-time AI.
Book Synopsis Synchronization and Ovarian Development in Dairy Cows and Heifers by : Rebecca L. J. Coral Escalante
Download or read book Synchronization and Ovarian Development in Dairy Cows and Heifers written by Rebecca L. J. Coral Escalante and published by . This book was released on 2012 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reproductive management is an important factor for improving reproductive efficiency in the dairy industry. Reproductive efficiency affects the profitability of the dairy herd by decreasing days not pregnant and increasing milk produced in a cow's lifetime. There are many reproductive programs used to synchronize the estrous cycle. Prostaglandin F2[alpha] (PGF2[alpha])-based programs synchronize estrus before artificial insemination (AI) after observed estrus. Some disadvantages to PGF2[alpha]-based reproductive programs are time requirements necessary for estrus detection (2 to 3 times/d for about 30 min) and lack of estrus activity observed in dairy cows (only about 40% will show estrus). An advantage to PGF2[alpha]-based reproductive programs is acceptable conception rates (about 45 to 60%) that can surpass timed AI (TAI). Reproductive programs that employ TAI are achieved by synchronization of ovulation with a series of PGF2[alpha] and gonadotropin releasing hormone (GnRH) injections followed by insemination 16 h later. Some of the advantages to synchronization of ovulation followed by TAI are: no estrus detection and acceptable conception rates (40 to 50%). Many reproductive programs include a presynchronization step. The advantage to presynchronization is a tightened synchrony by getting more cows and heifers in the same stage of the estrous cycle before estrous synchronization and AI or TAI. There are a variety of presynchronization methods used in cattle. One of the most common programs is two injections of PGF2[alpha] 14 d apart 12 d before initiation of Ovsynch (d 0 GnRH, 7 d, PGF2[alpha], 56 h, GnRH, 16 h, TAI) (Moreira et al., 2001). Another is double Ovsynch where the Ovsynch program is administered 7 d before another Ovsynch program (Giordano et al., 2012). Long-term progestogens can also be used as a means to presynchronize the estrous cycle and has been successful in beef cows and heifers. Long term progestogens, such as a CIDR (controlled internal drug release) for 14 d, will suppress estrus, inhibit ovulation, and induce the development of a persistent dominant follicle that can ovulate after CIDR removal (Ahmad et al., 1995; Revah and Butler, 1996; Roche et al., 1999). Ovulation of the dominant follicle allows for cows and heifers to be late in the luteal stage of the estrous cycle before PGF2[alpha] and AI or PGF2[alpha], 56 h, GnRH, 16 h, TAI. Presynchronization has shown to decrease the days to pregnancy. This is an advantage because it will directly affect the number of days a cow is not pregnant and the amount of milk she will produce in her lifetime. The objective of this research was to evaluate pregnancies per AI, ovarian follicular and luteal development of postpartum dairy cows and dairy heifers in response to long term progestin-based programs (14dCIDR) compared with PGF2[alpha]-based programs. Experiment 1 (Chapter 2) evaluated the use of a 14dCIDR-PGF2[alpha] program to a PGF2[alpha]-alone program for synchronizing dairy heifers before AI. Heifers were examined by real-time ultrasonography during treatment to assess the ovarian response. Heifers were also monitored for estrus following presynchronization and treatment of PGF2[alpha] to assess ovulation response. The 14dCIDR-PGF2[alpha] system resulted in more heifers with a larger CL at the time of PGF2[alpha]. This is ideal because of the greater luteolytic effects of PGF2[alpha] has on a more mature CL. The 14dCIDR-PGF2[alpha] heifers were AI and became pregnant sooner compared with the PGF2[alpha]-alone heifers. Experiment 2 (Chapter 3) evaluated the use of a 14dCIDR_TAI program compared with a PGF2[alpha]-based program in grazing dairy cows. The 14dCIDR_TAI program employed synchronization of ovulation before TAI and the PGF2[alpha]-based program employed synchronization of estrus with AI after observed estrus. The evaluation of reproductive efficiency for each program was examined. Cows assigned to the 14dCIDR_TAI program were AI early in the breeding season and were all AI by the end the breeding season compared with the PGF2[alpha]-based program. The PGF2[alpha]-based program had a greater first service conception rate (FSCR) compared with the 14dCIDR_TAI program but did not achieve a greater number of pregnancies after two inseminations. Experiment 3 (Chapter 4) evaluated the use of a 14dCIDR_TAI program compared with another common TAI program (Presynch-Oysynch56) in postpartum lactating dairy cows. Follicular dynamics and luteal development were monitored in both programs. Each program was evaluated for effectiveness to presynchronize the estrous cycle and establish pregnancy. The 14dCIDR_TAI and the Presynch-Ovsynch56 programs were comparable in their effectiveness to presynchronize the estrous cycle and establish pregnancy in cows that were cycling. Non-cycling cows treated with the Presynch-Ovsynch56 program had lesser conception rate compared with those that were cycling. There was no difference in conception rate with non-cycling or cycling cows treated with the 14dCIDR_TAI. Experiment 4 (Chapter 5) evaluated the use of the 14dCIDR_TAI program with or without PGF2[alpha] at CIDR removal. It is possible for cows to still have a CL after the end of the 14dCIDR treatment either due to longer estrous cycles or the cow was early in her estrous cycle when the CIDR was inserted. The addition of PGF2[alpha] may help improve the synchrony and conception rates after presynchronization of the estrous cycle before TAI. The addition of the PGF2[alpha] at CIDR removal demonstrated an increase in the number of cows that showed estrus after presynchronization but conception rates were comparable. Overall, the use of the 14dCIDR as means to presynchronize the estrous cycle has been demonstrated as an effective way to enhance the synchrony and decrease the interval to pregnancy in dairy cows and heifers.
Book Synopsis Utilization of Sex-sorted Semen in Beef Cattle by : Kolton Wyatt Aubuchon
Download or read book Utilization of Sex-sorted Semen in Beef Cattle written by Kolton Wyatt Aubuchon and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reproduction is one of the most important traits for cattle producers. The continued and consistent production of calves for market and replacement purposes is the backbone of many cattle operations' economic success. The value of male and female calves can vary greatly depending on the purpose that animal is meant to serve. This difference in value has made the ability to control the gender of a calf crop a topic of great interest. The development of sex-sorted semen has given producers the ability to shift the ratio of male and female offspring within their operation. The relative novelty of sex-sorted semen means there are still improvements being made to the technology and room for further adoption to occur. In the first chapter, a review of the literature encompasses the development of sex-sorted semen, its uses in different industries and operations, and its differences from unsorted semen. Three studies were conducted to evaluate the use of sex-sorted semen in beef cows and heifers. The second chapter describes research evaluating the use of X- and -Y- sorted semen in beef cows and heifers using various estrous synchronization and timing of insemination. The finding of this study further supports existing evidence of the importance of detection of estrus when utilizing sex-sorted semen and also showed the potential for use of Y-sorted semen in terminal mating systems. The third chapter evaluates the use of sex-sorted semen in beef heifers following synchronization using MGA-PG and insemination following heat detection. Results indicate that inseminating at a later time following observation of estrus behavior is advantageous when utilizing sex-sorted semen. The last chapter evaluated the difference between the novel 7&7 Synch and the classic 7-Day CO-Synch+CIDR estrous synchronization protocols following fixed-time AI (FTAI) with Y-sorted semen. Results of this study showed no difference between the 7&7 Synch and the 7-Day CO-Synch+CIDR protocols in the mature cows, but that the 7-Day CO-Synch+CIDR was more effective on two-year-old cows. Results of these studies indicate that sex-sorted semen can be utilized in beef cattle operations and acceptable pregnancy rates can be achieved. Further research is needed to improve the technology.
Book Synopsis Timing GnRH Administration with Split-time Artificial Insemination Following Administration of CIDR-based Protocols to Synchronize Estrus and Ovulation in Beef Heifers and Cows by : Brianne Elizabeth Bishop
Download or read book Timing GnRH Administration with Split-time Artificial Insemination Following Administration of CIDR-based Protocols to Synchronize Estrus and Ovulation in Beef Heifers and Cows written by Brianne Elizabeth Bishop and published by . This book was released on 2015 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Historically, adoption of AI within beef herds has increased due to improvements in methods to synchronize estrous and expanded use of fixed-time artificial insemination (FTAI) where all females are inseminated at a predetermined fixed time. Because pregnancy rates are higher among females that exhibit estrus prior to AI, split-time AI was developed as an alternative breeding strategy whereby insemination is delayed 20 to 24 hours (h) for females that fail to express estrus prior to a predetermined fixed time. Three experiments were designed to test hypotheses related to the timing and use of GnRH in breeding programs involving STAI based on results from previously published studies. Estrus was synchronized for heifers in experiment 1 with the 14-d CIDR-PG protocol, and for cows in experiment 2 using the 7-d CO-Synch + CIDR protocol. Females in each treatment that exhibited estrus by 66 h were inseminated at 66 h, whereas AI was delayed 24 h (90 h after PGF2?) for females failing to exhibit estrus by 66 h. Females in treatment 1 received GnRH 66 h after PGF2? irrespective of estrus expression; however, in treatment 2, GnRH was administered coincident with delayed AI only to females not detected in estrus at 66 h. GnRH administered to estrus females at 66 h did not affect AI pregnancy rate; however delaying GnRH to 90 h for non-estrous females at 66 h improved estrous response for cows but not for heifers, with no effect on AI pregnancy rate. A third experiment evaluated pregnancy rates of heifers that failed to exhibit estrus by 90 h after PGF2? following treatment with the 14-d CIDR-PG protocol. Treatments were compared on the basis of whether or not GnRH was administered concurrent with AI, 90 h after PG. There was no effect of treatment on AI pregnancy rate. Collectively, these results indicate: 1) GnRH is not required among females that exhibit estrus prior to AI; 2) delayed administration of GnRH increases total estrous response in cows when STAI is practiced; and 3) GnRH is not required when STAI is practiced in conjunction with the 14-d CIDR-PG protocol in heifers.
Book Synopsis Synchronization of Estrus in Beef Heifers and Cows with GnRH And/or CIDR-based Protocols by : Gonzalo Barquero
Download or read book Synchronization of Estrus in Beef Heifers and Cows with GnRH And/or CIDR-based Protocols written by Gonzalo Barquero and published by . This book was released on 2004 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Managing Cattle Reproduction by : Daniel V. Chavez
Download or read book Managing Cattle Reproduction written by Daniel V. Chavez and published by . This book was released on 2018 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Efficiency of reproduction is crucial for successful cow-calf operations. Cows naturally have varying timing of estrous cycles between cohorts and manipulation of current estrus synchronization and artificial insemination (AI) techniques may prove pivotal in increasing conception rates. The objective of these experiments was to determine if alternative methods of estrus synchronization or AI may increase incidence of successful fertilization and pregnancy, either by bull or AI. In Exp. 1, 168 (n = 84 each year) crossbred and purebred Angus two and three year old beef cows were randomly assigned to one of two estrus synchronization treatment groups: 1) a Controlled internal drug release (CIDR) and GnRH administration d-7, removal of CIDR and PG administration d 0, or 2) PG administration on d 5. Bulls were turned out d 0 at a bull to cow ratio of 1:17 for 90 d. Blood samples were taken approximately 30 d after bull turn out and 45 d after bull removal to determine pregnancy. Estrus detection patches were used to determine estrus. Although estrus response was greater in CIDR than PG (P = 0.02), early pregnancy (P = 0.92) and final pregnancy rates (P = 0.89) were not different. However, estrus response in the first 5 d was greater (P
Book Synopsis Comparison of Two Short-term Progestogen Based Estrous Synchronization Protocols in Yearling Heifers and Suckled Postpartum Cows of Bos Indicus X Bos Taurus Breeding by : Erin N. McKinniss
Download or read book Comparison of Two Short-term Progestogen Based Estrous Synchronization Protocols in Yearling Heifers and Suckled Postpartum Cows of Bos Indicus X Bos Taurus Breeding written by Erin N. McKinniss and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In Experiment 3, yearling heifers (n = 407) were synchronized with either the SSC +TAI treatment from Experiment 1 or 7-11 treatment that included melengestrol acetate (MGA; 0.5 mg/head/d) for 7 d with GnRH 4 d after the last day of MGA followed by DPG 7 d later. Estrus was detected and heifers were inseminated similar to Experiment 1. Heifers were distributed to treatment by reproductive tract score (RTS; Scale: 1=immature to 5= estrous cycling) and BCS. The 7-11 heifers had greater (P 0.05) ER (55.2 vs. 41.9%), CR (47.0 vs. 31.3%), and SPR (33.5 vs. 24.8%) compared to SSC+TAI heifers, respectively. Heifers exhibiting estrus at 60 h after PG (61.7%) had a greater (P
Book Synopsis Effects of Pubertal Status and Number of Estrous Cycles Prior to Breeding in Beef Heifers, Average Daily Gain on Reproductive Performance and Comparison of Two Fixed Time AI Estrus Synchronization Protocols by : Rebecca A. Vraspir
Download or read book Effects of Pubertal Status and Number of Estrous Cycles Prior to Breeding in Beef Heifers, Average Daily Gain on Reproductive Performance and Comparison of Two Fixed Time AI Estrus Synchronization Protocols written by Rebecca A. Vraspir and published by . This book was released on 2014 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reproductive success is the most important factor in beef cattle production and is affected by timing of pubertal onset in heifers, and reproductive biotechnologies utilized. Three studies were conducted to evaluate the effects of pubertal status, ADG, and 2 fixed time AI protocols on reproductive success in beef heifers. In the first study, heifers that were pubertal prior to breeding had a greater AI and overall pregnancy rate; produced more calves born within the first 21 d of the calving season; and weaned older, heavier calves than non-pubertal heifers. Additionally, heifers that had ≥2 estrous cycles, prior to the first breeding season, had a greater second season pregnancy rate than those heifers that had 0 or 1 estrous cycles prior to the first breeding season. In the second study, as ADG increased leading up to breeding the odds of attaining puberty increased for Gudmundsen Sandhills Laboratory heifers. For West Central Research and Extension Center heifers, as ADG increased the odds of puberty attainment decreased. Odds of pregnancy were affected by BW gain and pubertal status interaction; however, pubertal status had the greatest influence on increasing the odds of pregnancy. In the third study, 2 progestin-based fixed time AI protocols, MGA and 14-d CIDR, were compared to evaluate pregnancy rates. Fixed time AI pregnancy rate and final pregnancy rate was similar between MGA and 14-d CIDR. An economic analysis suggested synchronizing heifers with MGA was a more cost-effective treatment.
