Estrous Synchronization Protocol Research Articles

Evaluation of a needle-free injection system for administration of cloprostenol for luteolysis in lactating dairy cows

Luteolytic drugs are critical for managing reproductive success in dairy cows. Currently prostaglandin analogs are only ap­proved for intramuscular injection. The utilization of a needle and syringe for administration of any drug can result in needle-stick injuries to workers. Furthermore, needle-free injection systems have been shown to eliminate transmission of blood­borne pathogens, such as anaplasmosis, in cattle. Data on the efficacy of needle-free injection systems and their application in an estrous synchronization protocol has not been reported. The objective of the present study was to evaluate the effective­ness of utilizing a needle-free injection system (Pulse Needle­Free Systems, Lenexa, KS) for the intramuscular delivery of clo­prostenol (Estrumate®, Merck Animal Health, Madison, NJ) for the purpose of estrous synchronization in lactating dairy cows.

242 Comparison of GnRH administration day in the 7&7 Synch versus 8&6 Synch Protocol for fixed-timed artificial insemination in beef heifers

Abstract The research aimed to investigate the impact of reducing the time interval for progesterone exposure on the ovulatory follicle just before performing fixed-timed artificial insemination (FTAI). This was achieved by adjusting the timing of administering a gonadotropin-releasing hormone agonist (GnRH; specifically, 100 µg gonadorelin, known as Cystorelin). The study assessed the effectiveness of two estrous synchronization protocols, the “7 & 7 Synch” and a modified protocol, by examining estrus expression (EE) and the resulting pregnancy rates (PR) following FTAI. The research utilized frozen conventional Angus semen from Select Sires, Inc. (Plain City, OH), and involved 66 Angus-cross heifers from the beef cattle research unit near Fayetteville at the University of Arkansas. To ensure consistency, the heifers were divided into two treatment groups based on their cyclicity status (CYC) and age. CYC status was determined by assessing a reproductive tract score (RTS) 1 wk before the synchronization process. RTS scores ranged from 1 to 5, with RTS 1-3 indicating pre- or peripubertal status and scores of 4 and 5 indicating cycling. Heifers with an RTS of 1 and 2 were excluded from the study before synchronization commenced. Both treatment groups involved the insertion of a controlled internal drug-releasing device (CIDR; specifically, Eazi-breed, containing 1.38 g of progesterone) into the vagina on d -14. Simultaneously, a prostaglandin F2α analogue (PGF; 500 µg cloprostenol sodium, known as Synchsure) was administered. In the first treatment group (7&7), GnRH was administered on d -7, while in the second group (8&6), GnRH was given on d -6. In both cases, PGF was administered on d 0 when the CIDR was removed, precisely 72 ± 1 h before FTAI, along with another dose of GnRH. Estrus expression (EE) was assessed during FTAI by examining Estrotect patches (Rockway Inc., Spring Valley, WI). EE was considered present when a patch had 50% or more of its color rubbed off, and it was deemed absent when less than 50% of the color had worn off. Pregnancy rates (PR) were determined through ultrasound examination on d 55. EE and PR were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC). Statistical differences were declared at α ≤ 0.05 and tendencies declared between 0.05 < P ≤ 0.1. Heifers on the 8&6-d protocol had greater rectal temperatures at breeding compared with 7&7-d heifers (P < 0.0001). AI pregnancy rates were greater in heifers on the 8&6-d protocol compared with the heifers on 7&7-d protocol (P = 0.625) with average pregnancy rates of 39.4% and 30.3%, respectively. Overall, pregnancy rate was greater as well for the 8&6-d heifers compared with the 7&7-d heifers (P = 0.044), with mean overall pregnancy rates of 78.8% and 54.5%, respectively.

Effect of protected fatty acid supplementation on ovarian activity, reproductive hormone profiles and reproduction of Barki ewes under semiarid conditions

Abstract. The objective of this experiment was to evaluate the impact of dietary supplementation with rumen-protected fat (calcium soaps of fatty acids, CSFA) and/or hormonal superovulation using equine chorionic gonadotropin (eCG) on ovarian activity, changes in ovarian hormones, and reproductive performance in Barki ewes under semiarid conditions. A total of 39 non-pregnant Barki ewes, with an average body weight of 34.7 ± 0.25 kg and an average age of 3–4 years, were divided into four groups. The first group (9 ewes) served as the control, while the second group (10 ewes) received double doses of PGF2α, administered 9 d apart, and was superovulated with 600 IU (international unit) eCG. The third group (10 ewes) was supplemented with 30 g per head per day of rumen-protected fat. The fourth group (10 ewes) underwent the same superovulation protocol as the second group and was also supplemented with 30 g per head per day of rumen-protected fat. All the ewes were fed a basal diet. Ovarian activity was detected using ultrasonography during the estrus phase in all the groups, after which all the ewes were naturally bred with Barki rams. The results demonstrated significant (P<0.05) increases in estradiol 17-β (E2) and progesterone (P4) levels in the treated groups compared to the control group. Ewes in all the treated groups exhibited large follicles, with an overall mean diameter (≥5 mm) significantly higher than that of ewes in the control group. Although there were no significant differences between the treated and control groups, the ewes treated with CSFA and/or the eCG hormone showed tendencies to improve the reproductive traits of Barki ewes. Overall, the findings of this study demonstrated a positive effect of CSFA alone or in combination with an estrous synchronization protocol on ovarian activity in Barki ewes, as indicated by the number and size of follicles and the presence of large-sized follicles.

134 A 12-year summary of effects of body weight at breeding and synchronization protocols on reproductive success of Bos indicus-influenced beef heifers grazing warm-season grasses

Abstract A retrospective analysis of 5 studies (2011 to 2022) evaluated the effects of body weight and synchronization protocols before the start of breeding season on reproduction of Bos indicus-influenced beef heifers. Data were collected from 594 Brangus crossbred heifers weaned on average at 280 ± 26 d of age, allocated to bahiagrass pastures (4 to 5 heifers and 0.8 to 1.0 ha/pasture), and supplemented with soybean hulls-based concentrate (0.5 to 1.8% of body weight, (BW); dry matter basis] from 2 weeks post-weaning until the end of the breeding season (189 ± 24 days of supplementation). Heifers were initially sorted into those that were supplement (S) and were not supplemented (NS) assigned to an estrous synchronization protocol before the start of the breeding season. Then, within each synchronization group, heifers were sorted into those that were below (BE) or above (AB) the average BW of all heifers (300 kg) at the start of the breeding season (n = 130, 126, 146, and 192 for BE+NS, BE+S, AB+NS, and AB+S heifers, respectively). Data were analyzed using GLIMMIX procedure of SAS using synchronization, BW at breeding, and resulting interaction as fixed effects, and heifer (synchronization × BW), study, and pasture(study) as random effects. Effects of synchronization × BW at breeding and synchronization were not detected for heifer BW and overall average daily gain (ADG). However, AB heifers were always (P < 0.0001) heavier from post-weaning until the end of the breeding season and had (P < 0.0001) greater overall ADG than BE heifers. Effects of synchronization × BW at breeding tended (P = 0.07) to detected for puberty attainment at the start of the breeding season, which was least (P < 0.01) for BE+NS, did not differ between BE+S vs. AB+NS (P = 0.37), and was greatest for AB+S heifers (31, 66, 60, and 81 ± 7.4%, respectively). However, final pregnancy and calving percentages differed (P < 0.01) only for BE vs. AB heifers (68 vs. 81 ± 4.4% and 63 vs. 75 ± 5.2%, respectively). Effects of synchronization × BW at breeding tended (P = 0.10) to detected for percent of heifers calving within the first 30 days of the calving season, which was least (P < 0.03) for BE+NS and did not differ (P = 0.20) among BE+S, AB+NS, and AB+S heifers (48, 69, 61, and 64 ± 5.9%, respectively). Hence, in Bos indicus-influenced beef heifers, BW above 300 kg at the start of the breeding season led to improved overall reproductive performance compared to BW < 300 kg, whereas estrous synchronization protocols had positive effects to puberty attainment (regardless of heifer BW) and improved early calving distribution only when heifers were below 300 kg at the start of the breeding season.

13 Effects of an acclimation protocol during the handling events of the 7 d CO-synch + CIDR protocol on temperament and reproductive performance of Bos taurus commercial beef heifers

Abstract It has been previously reported that cattle temperament significantly impacts fertility to estrous synchronization (ES) protocols. In addition, enrolling heifers to acclimation protocols following weaning resulted in improved reproductive parameters with an increased proportion of acclimated heifers reaching puberty earlier when compared with non-acclimated cohorts. The objective of the present experiment was to assess the effects of an acclimation protocol during the handling events of an ES on changes in temperament and fertility to the ES protocol in Bos taurus commercial beef heifers. A total of 361 Angus-influenced commercial heifers from 5 different locations were enrolled in the experiment. Before enrolling heifers in the 7-d CO-Synch + CIDR protocol (d -10), individual heifers were evaluated for reproductive tract score (RTS), and chute score (CS) and stratified to receive acclimation (TRT) or to serve as control (CTRL). On d -10, heifers from TRT and CTRL groups received ear tags of different colors and individuals from CTRL and TRT were kept together in their pastures. Before each handling event of the ES (d 0,7,10), TRT heifers were sorted from CTRL and submitted to acclimation, which consisted of running heifers through the handling facilities without catching individuals in the restraining chute. Treatment heifers were then comingled with CTRL heifers, and all heifers were brought to the handling facilities for the ES event. Individual CS and exit velocities (EV) were recorded for all animals at all days (-10,0,7,10). Chute scores were recorded in a 1 to 5 scale, where 1 = calm, no movement; 2 = restless movements; 3 = frequent movement, vocalization; 4 = constant moving, vocalization, shaking of the chute; 5 = violent, continuous struggling. Individual estrus detection patch scores were assessed at the day of fixed-time artificial insemination (FTAI) based on percentage of activation, where 0 = lost; 1 = less than 25% activated, 2 = less than 50% activated, 3 = less than 75% activated, 4 = more than 75% activated. Pregnancy status was determined by rectal ultrasonography approximately 40 d after FTAI. Estrus detection patch scores did not differ between CTRL and TRT heifers (P = 0.1906). In addition, pregnancy rates to FTAI did not differ between TRT and CTRL heifers (56.81% and 52.74%; P = 0.3563). Reproductive tract scores (P = 0.777), EV (P = 0.9607) and CS (P = 0.990) did not differ between CTRL and TRT on d -10. However, CS, but not EV was decreased on d 7 (P = 0.001) and 10 (P = 0.0002) for TRT heifers when compared with CTRL. We conclude that enrolling heifers to an acclimation protocol during the handling events of the ES protocol was effective at decreasing excitability of heifers by the day of FTAI, as evidenced by decreased CS observed for TRT heifers on d 7, and 10 but did not support an increase in fertility to the ES protocol.

PSIII-7 Effect of Time of Estrus on Conception Rate for a Sexed Semen Artificial Insemination Protocol in Multiparous Beef Cows

Abstract Sexed semen artificial insemination is a breeding technique that allows producers to shorten breeding seasons, optimize genetics through use of superior semen, create calves based on sex preference, and increase profitability. Sexed semen is a technology that sorts semen by differences in DNA content between X (female) and Y (male) bearing sperm. However, sexed semen practices have yet to be widely used in beef cows due to reduced sperm numbers, low conception rates, and increased costs. The objective of this study was to determine the effect of time of estrus upon fixed-time artificial insemination (FTAI) of sex-sorted semen on conception rate using two different estrous synchronization protocols. Multiparous commercial beef cows (n = 73) were randomized by age, body condition score (BCS), and days post-partum at the University of Arkansas Livestock and Forestry Research Station in Batesville. Both synchronization treatments (TRT) used a controlled internal drug releasing device (Eazi-breed CIDR; 1.38g progesterone) inserted intravaginally on d -14 of the protocol simultaneous to administration of prostaglandin F2α (PGF; 500µg cloprostenol sodium; Estrumate). In the first treatment (TRT 1; 7&7 Synch), gonadotropin-releasing hormone (GnRH; 86µg gonadorelin; Fertagyl) was administered on d -7. In the second treatment (TRT 2; 8&6 Synch), GnRH was administered on d -6. Both treatments were then administered PGF simultaneous to CIDR removal on d 0, 66 ± 2h before FTAI and administration of GnRH. Standing heat (estrus) was visually detected every 3 h for 30 min intervals between CIDR removal and FTAI. Heat detection patches were used in conjunction with visual detection of estrus. Time of estrus was signified as time of standing immobile when mounted in combination with presenting a patch score of 4 (>75% color removed). Time of estrus (TD) was deviated from time of FTAI and categorized into three equal time groups (Grp 1 = 0 to 11.0 h; Grp 2 = 11.01 to 22.0 h; and Grp 3 = 22.01 to 33.0 h). Conception rate (CR) was determined via ultrasound 37 ± 2 d after FTAI. Data were analyzed using the GLIMMIX procedure of SAS 9.4. CR did not differ by age of dam (P = 0.58), BCS (P = 0.48), or TRT (P = 0.83). However, TD had an effect on CR (P = 0.002); and resulted in CR of 45% (Grp 1), 87% (Grp 2), and 42% (Grp 3). In conclusion, these results indicate artificially inseminating cows with sexed semen between 11.01 and 22.0 h after time of standing estrus will increase pregnancy rates for multiparous commercial beef cattle.

Effect of different Estrous Synchronization Protocols on Reproductive Performance of Barbari Goats

Effect of different Estrous Synchronization Protocols on Reproductive Performance of Barbari Goats

Effect of hCG administration on ovulation and estrus in Saanen goats subjected to short-term estrus synchronization protocol during the breeding season

This study aimed to compare the effect of hCG administered at 24 or 36 h following a short-term estrus synchronization treatment on the ovulation time and estrus parameters in non-lactating Saanen goats during the breeding season. The estrous cycles of does were synchronized with an intravaginal sponge containing 60 mg of medroxyprogesterone acetate (MAP) for six days, and an injection of 125 µg of d-cloprostenol at the time of sponge insertion in addition to an injection of 300 IU of eCG 24h before sponge removal. After removal of the sponges, does were injected intramuscularly either 1 ml physiological saline (0.9% NaCl) solution after 12 h (Group1/Control; n=10), 100 IU hCG after 24 h (Group2; n=9) or 100 IU hCG after 36 h (Group3; n=9). Estrus behavior after sponge removal was observed twice daily for 84 h using teaser bucks and transrectal ovarian ultrasonography was performed twice a day for seven days to determine small, medium and large follicle numbers, luteal development and the time of ovulation. Blood samples were collected on the same days to determine serum progesterone (P4) and estradiol (E2) concentrations. No significant differences were observed in terms of estrus parameters, ovarian structure and serum P4 and E2 concentrations between the hCG-treated groups and the control group. Average values observed for all groups: estrous response (53.57%), the interval from sponge removal to estrus and ovulation (35.2 h and 67.86 h, respectively), duration of estrus (18.4 h), the interval from estrus onset to ovulation (50.37 h), ovulation rate (96.43%), number of ovulations (1.36), ovulatory follicle diameter (6.86 mm), corpus luteum diameter (8.22 mm), follicle and luteal growth rate (1.17 and 0.68 mm/day, respectively). In conclusion, administration of hCG at 24 or 36 h following a short-term estrous synchronization protocol does not affect ovulation time, estrus parameters, and serum P4 and E2 concentrations in goats during the breeding season.

94 Changes in Vaginal Microbiome of Beef Cows Enrolled in an Estrous Synchronization Protocol

Abstract Vaginal pH and microbiome have been reported to influence fertility in women. In cattle, estrous synchronization protocols are a great tool to overcome infertility; however, the effects of the hormones administered in the protocol on vaginal microbiome and pH are unknown. A total of 24 cows were enrolled in the 7-d Co-Synch + controlled internal drug release (CIDR) protocol and had individual vaginal flushes collected during the handling events of the protocol on days 0, 7 and on day 10 at timed-artificial insemination (TAI). Flushes were used for pH analysis and DNA extraction. Extracted DNA was submitted to analysis by whole genome shotgun sequencing. Pregnancy status was assessed by ultrasonography 35 days after TAI. Firmicutes was the most abundant phylum, followed by Proteobacteria, and Actinobacteria for all collection days. Bacteria from the Clostridia genus were the most abundant in all samples. Greater alpha Shannon diversity (within sample diversity) was observed for pregnant animals on day -10 compared with non-pregnant animals at the phylum, class, and order (P < 0.01), as well as family, and genus level (P < 0.001). Overall, Shannon diversity was decreased on day 7 compared with day 0 (P < 0.05 at class and order level; P< 0.01 at genus and family level) and was greater at TAI compared with day 7 (P < 0.01 at the phylum, class, and order level; P < 0.001 at family and genus level). No differences were observed for Shannon diversity between samples from D0 and TAI (P > 0.05). No correlations between Shannon diversity were observed in relation to vaginal pH (P > 0.1). Bray-Curtis analysis (between sample diversity) revealed clustering by day (P < 0.05 at the order, family, and genus level) and a tendency (0.1 < P < 0.05) at the phylum and class level. In conclusion, greater fertility was observed for animals with greater within sample diversity prior to protocol initiation. Furthermore, vaginal bacterial diversity changes throughout the protocol, with decreased diversity observed on day 7 of the protocol, but restored diversity on day0 at TAI.

58 Reproductive Performance of Beef Cow-Calf Operations in VA with a Fall or Spring Breeding Season

Abstract Establishing two breeding seasons (Fall and Spring) is a common practice in the southeast USA, including VA. We performed a retrospective analysis of data from 11 years, 22 breeding seasons and 14 locations in VA to compare reproductive performance between Fall and Spring breeding seasons. A total of 30,191 breeding records (24,032 for cows and 6,259 for heifers) from the VA Department of Corrections beef cattle operations were analyzed. Every year, each cow and heifer were enrolled in estrous synchronization protocols and received fixed-time artificial insemination (TAI) and were then exposed to natural service bulls for an approximately 65-day breeding season. Fall breeding occurred from November until January, and Spring breeding from March until May. Body condition score (BCS; 1 to 9, scale) was determined at the initiation of the TAI protocol. Estrus detection before TAI was performed by scoring an estrus detection aid prior to insemination. Pregnancy rate was determined by ultrasonography between days 55-65 post-TAI and 40-50 after the end of the breeding season. Data were analyzed using the SAS GLIMMIX procedure for binary data and MIXED procedure for continuous data. Average BCS was greater (P < 0.001) for Fall cattle than Spring cattle (5.7 ± 0.02 and 5.1 ± 0.02, respectively); however, days postpartum at TAI was similar between Fall and Spring (P = 0.645; 77.8 and 76.2 ± 0.5 days, respectively). Pregnancy rate to TAI differed (P < 0.0001) between Fall and Spring, 53.0 ± 0.03% and 48.6 ± 0.05%, respectively. Interestingly, estrus expression was greater (P < 0.001) for Spring than Fall (58.4 ± 0.05% and 50.4 ± 0.06%, respectively) and also was greater for cows that became pregnant to TAI compared with cows that failed to become pregnant to TAI (P < 0.001; 61.7 ± 0.03% and 46.9 ± 0.04%, respectively). End of breeding season pregnancy rate differed between season and was greater for Fall than Spring (P < 0.001; 90.7 ± 0.04% and 87.9 ± 0.04%, respectively). Calf birth weight was similar between seasons (P = 0.478; 34.1 and 34.4 ± 0.09 kg, for Fall and Spring, respectively). However, 205-day adjusted weaning weights differed (P < 0.001) between seasons with Spring calves being heavier than Fall calves (246.3 ± 0.12 kg and 227.8 ± 0.21 kg, respectively). In conclusion, for beef cow-calf operations in VA reproductive performance is enhanced for Fall breeding seasons; however, weaning weights were greater for calves born during the Spring seasons.

73 Comparison of GnRH Administration day in the 7 & 7 Synch Versus 8 & 6 Synch Protocol for Fixed-Timed Artificial Insemination in Beef Heifers

Abstract The study was conducted to identify effects of a decreased interval of progesterone on the ovulatory follicle before fixed-timed artificial insemination (FTAI) by altering the day of a gonadotropin-releasing hormone agonist (GnRH;00µg gonadorelin; Cystorelin) administration. Evaluation of the 7 & 7 Synch and altered estrous synchronization protocols was done using estrus expression (EE) and FTAI pregnancy rates (PR). Using frozen conventional Angus semen (Select Sires, Inc. Plain City, OH), Angus-cross heifers (n = 68) from the University of Arkansas beef cattle research unit near Fayetteville were stratified into two treatment groups by cyclicity status (CYC) and age. Cyclicity status was determined by using a reproductive tract score (RTS) taken one week prior to beginning synchronization. Scores ranged from 1-5, where RTS 1-3 were considered pre- or peripubertal while scores 4 and 5 were considered cycling. Heifers with a RTS of and 2 were culled prior to synchronization. Each treatment used a controlled internal drug releasing device (CIDR; Eazi-breed; 1.38g progesterone) inserted intravaginally on –14 d simultaneous to the administration of a prostaglandin F2α analogue (PGF; 500 µg cloprostenol sodium; Synchsure). In the first treatment (7 & 7), GnRH was administered on –7 d. In the second treatment (8 & 6), GnRH was administered on –6 d. Both treatments were then administered PGF simultaneous to CIDR removal on 0d, 72 ±h prior to FTAI and the administration of GnRH. Estrus expression was recorded at the time of FTAI using an Estrotect patch (Rockway Inc., Spring Valley, WI). Estrus expression was determined as a patch with 50% or more of the color rubbed off. On the contrary, a patch with less than 50% of the color rubbed off, was not. Pregnancy rates was determined via ultrasound on 58 d. Estrus expression and PR were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC) with CYC as a fixed effect for EE; CYC and EE as fixed effects for PR. Statistical differences were determined with α ≤ 0.05 and tendencies were observed between 0.06-0.1. There was an effect of CYC on EE (P = 0.001) and a tendency to affect PR (P = 0.088). There was no treatment effect on EE (P = 0.892) or PR (P = 0.708). In conclusion, the altered time of GnRH administration in the 7 & 7 synch at 72 ± hours did not affect EE or PR; however, research will continue to investigate adjusting length of time from PGF injection to FTAI to evaluate the effects.

74 Ovulatory Follicle and Corpus Luteum Development ofBos Taurus Cows Under Nutrient Restriction

Abstract Establishment and maintenance of pregnancy is a central concern to the cattle industry, as it strongly impacts efficiency and profitability of beef cow-calf operations. The objective of this study was to determine if nutrient restriction impacts ovulatory follicle size and corpus luteum (CL) volume of Angus cows enrolled in estrous synchronization. A total of 26 Angus cows were housed at the Virginia Tech – Shenandoah Valley Agricultural Research and Education Center (SVAREC) equipped with a Calan gate system for individual animal intake, stratified by body weight (BW) and randomly assigned to one of two treatments: 1) a maintenance diet that provided 100% of nutrient requirements (MTN; n = 13) or 2) a diet providing 70% of nutrient requirements (REST; n = 13). Nutrient requirements were calculated and adjusted weekly based on BW using the 2016 NRC version of Beef Cattle Nutrient Requirements Model Software. Cattle underwent an acclimation period of4 days and were exposed to nutritional treatments for 30 days before estrous synchronization. Body weight was measured daily using an automated scale, and a conventional livestock scale at the beginning and end of the experiment. Cows were synchronized using a 7-day CO-synch + CIDR protocol beginning on day -10. An estrus alert patch was applied on day -3 and read on day 0 to assess expression of estrus. Ultrasonography of the ovaries was performed at each event of the estrous synchronization protocol. Data were analyzed using the MIXED procedure of SAS. Initial BW was similar between treatments (P = 0.07; 600 ± 32 kg), but MTN compared with REST cows had greater final BW (P < 0.01; 687 ± 24 and 556 ± 27 kg, respectively) and greater average daily gain (1.35 ± 0.18 and -0.72 ± 0.21 kg/d, respectively). Estrus expression was numerically greater (P = 0.185) MTN (84.62%) than REST (61.54%) cows. Diameter of the largest follicle was similar (P = 0.851) between treatments at the CIDR insertion (12.6 ± 0.6 mm) and CIDR removal (12.9 ± 0.4 mm), but were greater for MTN than REST cows at 60 hours after CIDR removal (14.01 ± 0.6 and 12.37 ± 0.5 mm, respectively). Volume of CL was similar (P > 0.01) at 5 (3211 ±13 mm3) and 7 (5280.3 ± 212 mm3) days after ovulation. In conclusion, nutrient restriction during estrous synchronization negatively affects diameter of the ovulatory follicle, but it did not affect subsequent CL volume in mature Angus cows.

55 Investigating the Potential Benefits of an Immunostimulant (Mycobacterium Cell Wall Fraction) Treatment on Increased Pregnancy Success of Embryo Transfer Recipients

Abstract Modulating the vaginal and uterine microbiome through the use of immunostimulants has the potential to improve fertility in cattle. The object of this study was to evaluate the potential benefits of an immunostimulant, mycobacterium cell wall fraction (MCWF), to increase pregnancy success of embryo transfer (ET) recipients. The three main objectives of this study were: determining if injecting ET recipient cows with MCWF increased proportion of cows with a corpus luteum (CL) on ET day, identifying differences in CL volume and progesterone concentration at the time of ET, and determining if ET recipients that received MCWF have greater pregnancy rate. A total of 926 beef cows at eight different locations were enrolled in this study. Primiparous and multiparous cattle were enrolled in a 7-day CO-Synch + CIDR estrous synchronization protocol. During this protocol, cows received an injection of GnRH (100-μg) at CIDR (controlled internal drug release) insertion [d -9], a prostaglandin F2α injection (25 mg), and CIDR removal [d-2] followed by another injection of GnRH (100 μg; d 0) within 60-66 hours after CIDR removal. At each location at (d 0), cows were sorted based on BCS and days post-partum and randomly assigned to one of two treatments: 1) MCWF- a single intramuscular injection (5 mL) of MCWF at (d 0; Amplimune, NovaVive Inc.; n = 452) or 2) Control- a single intramuscular injection (5 mL) of saline (n = 474). Seven days after (d 7), cows were examined by ultrasonography to determine if a CL was present. Recipient cows that had a CL received ET with a frozen or fresh in vivo or in vitro produced embryo in the ipsilateral uterine horn to the CL, with embryo type and grade balanced between treatments. Blood samples were collected in one location (n = 98) for analysis of plasma concentration of progesterone on (d 7) ET day. Pregnancy diagnosis was then performed by ultrasonography between 30 and 90 days of gestation. Data were analyzed using the GLIMMIX and MIXED procedures of SAS. Cow BCS and days postpartum were similar (P > 0.10) between treatments (5.5 ± 0.6 and 103 ± 14 days, respectively). Recipient cow utilization rate was similar between treatments (P = 0.49; 81.2 ± 0.42%). At the time of ET MCWF had larger CL than Control cows (5,768.6 ± 133.7 and 5,408.0 ± 128.5 mm3, respectively, P = 0.03). and increased progesterone concentration (2.68 ± 0.17 and 2.18 ± 0.14 ng/mL, respectively, P = 0.01). However, pregnancy rate to ET was similar (P = 0.922) between treatments (60.9 and 61.3 ± 0.05% for Control and MCWF, respectively). In conclusion, treatment of ET recipient cows with MCWF increased CL volume and concentration of progesterone at the time of ET but failed to generate greater pregnancy rates.

Estrous synchronization in cattle, sheep and goat

Synchronization of estrous refers to manipulating the estrous cycle or induction of estrous to bring a large number or group of female animals into estrous at a short, determined time. An estrous cycle is a rhythmic event in the female animal from one estrous phase to the next. The normal estrous cycle length is 21 days in cows, 20 days in doe, and 17 days in the ewe. The hormones used in estrous synchronization are estrogen, progesterone, GnRH, and prostaglandin. Estrous synchronization helps shorten the breeding period instead of females being bred over a period of normal length, and this depends on the treatment protocols to be followed. Combining GnRH with prostaglandin F2α (PGF2α) and a progesterone-based synchronization program has shown a novel direction in cattle's estrous synchronization, which causes manipulation in follicular development. Estrous synchronization protocol should be followed based on managemental capabilities and expectations of the farmer. This review article was compiled to summarize the protocols used for estrous synchronization in different species.

Effect of Progestin based Estrus Synchronization Protocol on Estrus Parameters, Hormonal Profile and Vaginal Cytology in Surti Goats

This investigation was conducted to study the effect of progestin and prostaglandin-based estrous synchronization protocol on estrus parameters, hormonal profile and vaginal cytology in Surti goats. Ten non-pregnant Surti goats were selected and subjected to estrus synchronization with intra-vaginal progesterone sponges (60 mg Medroxyprogesterone acetate, MAP) for 11 days followed by PGF2α injection (125 μgCloprostenol). Whole blood was collected on day 0 (before treatment), day 5, 11 (after treatment), at proestrus, estrus and diestrus for analyzing progesterone as well as estrogen hormone concentration. The vaginal exfoliative cytology was studied at proestrus, estrus and diestrus. Estrus parameters such as induction rate was 100%, time of onset of estrus from PG injection was 29.70 ± 1.06 h and duration was 30.74 ± 0.19 h. Significantly higher population of parabasal cells and superficial cells were observed during proestrus, intermediate cells in diestrus and cornified cells during estrus. At estrus, level of progesterone was lowest and estrogen was highest. Combination of progestin and prostaglandin-based protocol is successful in synchronization of estrous cycle with 100% estrus induction rate in Surti goats. Further in addition to other signs, vaginal exfoliative cytology can also be used for determining different phases of estrous cycle.

Delayed Timing of Insemination Relative to Estrus Improves Pregnancy to Artificial Insemination With Sex-Sorted Semen in Beef Heifers

Objective: The objective was to evaluate the effect of timing of artificial insemination (AI) relative to the onset of estrus on pregnancy outcome when using sex-sorted semen in beef heifers. Study Description: Beef heifers were subjected to the melengestrol acetate with prostaglandin (MGA-PG) estrous synchronization protocol and visually observed for estrus every four hours for five days following injection of PG. Following detection of estrus, heifers were inseminated with semen sorted to contain X-chromosome bearing sperm cells (4.0 × 106 live cells per 0.25 mL straw of SexedULTRA 4M). Heifers were retrospectively categorized into one of three intervals from estrus onset to insemination: 1) 12.5–15.9 hours; 2) 16.5–21.0 hours; and 3) 21.4–27.5 hours. Results: Heifers with the shortest interval (12.5–15.9 hours) from estrus onset to insemination had a similar (P > 0.10) AI pregnancy rate as compared with heifers with the interval from estrus onset to insemination of 16.5 to 21 hours. Heifers inseminated 21.4 to 27.5 hours following estrus onset achieved a greater (P ≤ 0.05) AI pregnancy rate than heifers inseminated 12.5 to 15.9 hours following estrus onset. The Bottom Line: Insemination of beef heifers with sex-sorted semen later than 21 hours after estrus onset appears to improve pregnancy rate to AI when compared to earlier insemination times.

The Role of Housing Conditions on the Success of Artificial Insemination in Intensively Reared Dairy Ewes in Greece.

Simple SummaryArtificial insemination (AI) is a powerful tool for animals’ genetic improvement. However, its application in sheep remains relatively limited due to inconsistent results, since the success of the method is dependent on many factors. In our study, we investigated the impact of housing conditions during the summer period on the fertility of dairy sheep in Greece, after cervical AI with cooled semen. The pregnancy rate was found to be negatively affected by the ambient temperature and Temperature-Humidity Index inside the shed, space availability, frequency of bedding renewal, and outdoor access. Appropriate housing conditions could help to increase pregnancy rates following AI during the summer months.The objective was to assess the effect of housing conditions during the summer months on the success rates of cervical artificial insemination (AI) with cooled semen, in intensively reared dairy ewes in Greece. The study involved 2083 Lacaune ewes from 23 flocks that were serviced during May to September. An estrous synchronization protocol with the insertion of progestogen sponges for 14 days and eCG administration at sponge removal, was used. All ewes were inseminated 54–57 h after sponge removal with cooled semen (15 °C) from 10 Lacaune rams. Pregnancy diagnosis was performed via trans-dermal ultrasonography at 35–40 days after AI. Data recording started the day after sponge placement (15 days prior to AI), and lasted up to 14 days after AI. Daily records included temperature, relative humidity, and Temperature-Humidity Index (THI) inside the shed. Available space and volume per animal, frequency of bedding renewal, access to a yard, and indoor light were also recorded in each farm. Binary logistic regression of data records showed that temperature and THI increases at days −15 to +4 around AI (day 0) had a negative effect on pregnancy rates (reducing the likelihood of pregnancy by 3–6% and 7%, respectively). The latter also decreased significantly (p < 0.05) in farms with high stocking density, non-frequent bedding renewal, and outdoor access by ewes (by 30%, 34%, and 44%, respectively). Overall, the results indicate that appropriate housing conditions are warranted to increase the success of AI in dairy ewes during the summer months.

311 Administering a Bovine Appeasing Substance to Beef Heifers During an Estrous Synchronization Protocol and its Impacts on Temperament and Pregnancy Rate

Abstract This experiment evaluated the impacts of administering a bovine appeasing substance (BAS) to Bos taurus (angus crossed) beef replacement heifers at the initiation of an estrous synchronization (TAI) protocol on their temperament and pregnancy rates. A total of 348 heifers at four locations were stratified by body weight (BW); reproductive tract score (RTS), and temperament score [TS; average of exit velocity (EV) and chute score (CS), determined at the day of initiation of TAI) and assigned to receive BAS (IRSEA Group, Quartier Salignan, France; n = 173) or placebo (water; CON; n = 175). Treatments (5 mL) were topically applied to the nuchal skin area of each heifer at the initiation of the TAI protocol. Within location, heifers were allocated to pens (6 pens per treatment; pen being the experimental unit) and received a free-choice total mixed ration during the duration of the experiment. Temperament (EV, CS) was assessed three times (days 0, 7 and 9) during the TAI protocol by the same trained technician. Pregnancy rate was determined by ultrasonography between days 45 and 55 post TAI. Heifer BW (379.5±5 kg), RTS (3.8±0.06), CS on days 0, 7 and 9 (2.33±0.06, 2.08±0.04, and 1.91±0.04, respectively), and EV on days 0, 7 and 9 (1.35±0.03, 1.28±0.03, and 1.39±0.03 m/s, respectively), and estrus expression prior to TAI (40.2±5.9%) were similar (P&amp;gt;0.10) between treatments. Pregnancy rate to TAI differed among locations (P&amp;lt; 0.05); however, it was not affected by treatment (39.7±8.2% and 41.0±3.7% for CON and BAS, respectively), with no treatment by location interaction. In conclusion, administration of BAS to beef heifers at the initiation of a TAI protocol did not alter temperament, measured as CS and EV, and failed to increase pregnancy rates.

PSI-5 Comparison of 7&amp;7 Synch and 7-day Co-Synch + Cidr Protocols in a Fixed-Time ai System on Beef Cows Using Y-Sorted sex-Selected Semen

Abstract The 7&amp;7 Synch and the 7-day CO-Synch+CIDR fixed-time estrous synchronization protocols were compared among mature and two-year-old lactating postpartum Angus and SimAngus cows (n=201). Mature (n=63) and two-year-old (n=36) cows treated with the 7&amp;7 Synch received an injection of prostaglandin F2α (PGF; 25 mg dinoprost tromethamine) at the same time as insertion of an intravaginal progesterone-releasing insert (CIDR; 1.38g progesterone) on Day -17, gonadotrophin-releasing hormone (GnRH; 100 μg gonadorelin) on Day -10, and PGF at time of CIDR removal on Day -3. Mature (n=65) and two-year-old (n=37) cows in the 7-day CO-Synch+CIDR groups received an injection of GnRH on Day -10 that coincided with CIDR insertion and received PGF at the time of CIDR removal on Day -3. Fixed-timed AI (FTAI) by a single technician using Y-chromosome-bearing sex-sorted semen (4x106 sperm/unit of SexedULTRA 4M) from one of two Charolais bulls occurred on Day 0, 70 hours after PGF injection. Seven days later bulls were pastured with cows for the remainder of the breeding season. Transrectal ultrasound was performed 77-83 days after AI and fetal size was used to differentiate AI and natural service pregnancies. Within the mature cows and two-year-old age groups, the GLIMMIX procedure in SAS was used to compare FTAI and breeding season pregnancy rates with estrous synchronization treatment and sire as main effects. No differences (P=0.41) were observed amongst mature cows in FTAI pregnancy rates between the 7&amp;7 Synch (52.4%) and the 7-day CO-Synch+CIDR (44.9%) treatments. A greater (P=0.05) proportion of two-year-old cows were pregnant to FTAI following treatment with the 7-day CO-Synch+CIDR (56.7%) as compared to the 7&amp;7 Synch (33.4%). A greater (P=0.02) proportion of two-year-old cows in the 7-day CO-Synch+CIDR treatment (91.9%) were pregnant at the conclusion of the breeding season as compared with the 7&amp;7 Synch (69.7%).

PSIII-5 Evaluation of Gnrh Administration day in the 7 &amp; 7 Synch Protocol for Fixed-Timed Artificial Insemination in Multiparous Beef Cows

Abstract The objective was to determine the effects of a decreased interval of progesterone on the ovulatory follicle prior to fixed-timed artificial insemination (FTAI) in a 7 &amp; 7 Synch estrous synchronization protocol using estrus expression (EE), FTAI pregnancy rates (AIPR) on 37±2d, and overall pregnancy rates (OPR) after a 60d bull exposure 90±2d determined via ultrasound. Using conventional Angus semen, multiparous Angus-cross cows (n=201) from two locations were randomized by age and days post-partum into two treatments. Both treatments used a controlled internal drug releasing device (Eazi-breedTM CIDR; 1.38g progesterone) inserted intravaginally –14d of the protocol simultaneous to administration of prostaglandin F2α (PGF; 500µg cloprostenol sodium; Estrumate®). In the first treatment (7&amp;7), gonadotropin-releasing hormone (GnRH; 86µg gonadorelin; Fertagyl®) was administered on –7d. In the second treatment (8&amp;6), GnRH was administered on –6d. Both treatments were then administered PGF simultaneous to CIDR removal on 0d, 66±2h prior to FTAI and administration of GnRH. EE was determined at the time of artificial insemination using an EstrotectTM patch (Rockway Inc., Spring Valley, WI). EE was signified as a patch with 50% or more of the color rubbed off or missing. Subsequently, a patch with less than 50% of the color rubbed off, was not. AIPR, OPR and EE were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC.). There was a significant effect on EE (P=0.01), a tendency on PR (P=0.08), and no effect on OPR (P=0.53) by treatment. EE, AIPR, and OPR for 7&amp;7 were 95±2.1%, 82±3.7% and 96.7±1.7% and for 8&amp;6 were 86±4.0%, 91±3.1% and 98±1.5%, respectively. In conclusion, the altered timeframe of GnRH administration affected EE and tended to affect PR in multiparous beef cows, suggesting that GnRH administration may improve PR when administered 6d, instead of 7d, prior to CIDR removal.