Sire effect on the pregnancy outcome in beef cows synchronized with progesterone based Ovsynch and CO-Synch protocols

Animal Reproduction Science 104 (2008) 1–8

Sire effect on the pregnancy outcome in beef cows synchronized with progesterone based Ovsynch and CO-Synch protocols R. Kasimanickam a,∗ , J.B. Hall b , J.F. Currin a , W.D. Whittier a a

Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Duckpond Drive, Phase III, Blacksburg, VA 24061, USA b Department of Animal and Poultry Sciences, College of Agricultural and Life Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA Received 27 October 2006; accepted 2 January 2007 Available online 10 January 2007

Abstract The objective was to determine the sire effect on the pregnancy outcome in beef cows in which stage of estrus was synchronized with progesterone based fixed-time artificial insemination (AI) protocols. Three Angus sires with more than 300 breedings were evaluated for differences in pregnancy outcome from 1868 inseminations. Angus cross beef cows (N = 1868) were synchronized with Ovsynch-CIDR or CO-SynchCIDR protocols for fixed-time AI. Cows in both groups that showed estrus on day 9 before 1500 h were designated to Selectsynch-CIDR group and were inseminated according to AM-PM rule. Results indicated that Sire 2 had lower fixed-time AI pregnancy rate compared to Sire 3 (48.1% versus 58.7%; P = 0.01). Significant sire × synchronization program and sire × location interactions were observed for fixed-time AI (P < 0.05). Sire 2 had a lesser fixed-time AI pregnancy in both Ovsynch-CIDR and CO-Synch-CIDR groups compared to Sire 3. In two of four locations, Sire 2 had a lesser fixed-time pregnancy rate compared to Sire 3. No sire differences were observed in AI pregnancy for cows in Selectsynch-CIDR group. In conclusion, evidence in this study suggest that there are differences in sire fertility when they were used in fixed-time AI protocols, possibly due to the sire differences in sperm capacitation process. Further studies are needed to investigate association of the sire differences in fixed-time AI protocols with sire differences in the sperm capacitation process. © 2007 Elsevier B.V. All rights reserved. Keywords: Sire fertility; Beef cows; Synchronization; Pregnancy rate

∗

Corresponding author. Tel.: +1 540 231 6778; fax: +1 540 231 1676. E-mail address: [email protected] (R. Kasimanickam).

0378-4320/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2007.01.003

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1. Introduction The reproductive performance of the individual beef herd is extremely important and plays a major role in its financial success. Currently, most commercial beef cows and a large proportion of purebred beef cows are bred by bulls. To improve genetics within a herd, the use of artificial insemination (AI) utilizing proven purebred bulls is of utmost importance (Barth, 1993). Success with AI has been highly dependent on accurate heat detection, timing of insemination, use of high quality semen, and proper insemination technique. Numerous studies with embryo quality, pregnancy and non-return rate have investigated the optimal time of AI relative to the stage of estrus and concluded that 12–16 h after the onset of estrus is the optimal time for breeding (Schiewe et al., 1987; Pursley et al., 1998; Dalton et al., 2000, 2001; Sartori et al., 2004;). In dairy cattle, Dalton et al. (2001) showed a 98% fertilization rate for 0 h natural service after onset of estrus compared to 67% and 79% for 0 and 24 h for AI after the onset of estrus, respectively. Also in the same study another experiment reported a greater (82%) fertilization rate for 24 h AI compared to 0 h AI (66%). Similar fertilization rates and transferable embryo rates have been reported by Schiewe et al. (1987) in beef cows when AI was performed with high quality semen at 24 h after the onset of estrus compared to AI at 12, 36 and 48 h after onset of estrus. Macmillan and Watson (1975) studied the effects of the time interval from estrus to AI on nonreturn rates of sires. They have selected groups of sires with different fertility to AI cows at different stages of estrus and concluded that the fertility varied between sires within each estrus to AI interval. The lack of a decline in non-return rate at early insemination among above average fertility sires compared to average and below average fertility sires indicates sire fertility is closely associated with sperm longevity in female reproductive tract. This indicates that fixedtime AI (AI) may magnify the differences in sire fertility due to variation in time from AI to ovulation (DeJarnette et al., 2004). This fertility difference can potentially be utilized to select a specific sire for a particular synchronization program which may result in a higher pregnancy rate. The objective of the present study was to determine the sire effect on the pregnancy outcome in beef cows synchronized with progesterone based Ovsynch and CO-Synch fixed-time AI protocols. 2. Materials and methods 2.1. Estrous synchronization and insemination Data used in this study were retrospectively collected from 2004 and 2005 AI breedings that occurred on four Virginia correctional center beef farms. Sires (N = 3) with satisfactory semen variables, which had more than 300 fixed-time AI breedings were selected and their breeding data were used for the present study. The cows selected for the analysis were synchronized with progesterone based protocols (Fig. 1). Briefly, Angus crossbred suckled beef cows (N = 1868) at four locations were estrous synchronized with 100 ␮g of gonadotropin releasing hormone (GnRH; Cystorelin® , Merial, Athens, GA, USA) + controlled internal drug release device (CIDR; Eazi-BreedTM CIDR® , Pfizer Animal Health, New York, NY, USA) on day 0, 25 mg of PGF2␣ (Lutalyse® , Pfizer Animal Health, New York, NY, USA), Kamar device and CIDR device removal on day 7 and received either 100 ␮g of GnRH 48 h after PGF2␣ on day 9 (Ovsynch-CIDR), and fixed-time AI 16 h after GnRH on day 10 (65.8 ± 2.3 from PGF2␣ ) or 100 ␮g of GnRH on day 10 (CO-Synch-CIDR) at the time of AI (63.2 ± 4.2 from PGF2␣ ). In both groups, cows that showed estrus by exhibiting activated Kamar devise before 1500 h on day 9 were designated to

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Fig. 1. Schematic representation of synchronization programs.

Selectsynch-CIDR group and were inseminated using AM-PM rule. Two weeks later bulls were penned with cows for subsequent breeding. 2.2. Pregnancy determination The pregnancy status of each cow was determined 70 days after fixed-time AI either by perrectal palpation or by trans-rectal ultrasonography (Sonosite 180Plus, Sonosite Inc., Bothell, WA, USA). Pregnancy rates were calculated by dividing the number of cows that were diagnosed pregnant by the total number of cows for each sire and for each treatment group. Within the farm, cows inseminated with semen from different sires (apart from three study sires) were excluded in the analysis. 2.3. Statistical analyses Data were analyzed with a statistical software program (SAS Version 9.1 for Windows, SAS Institute, Cary, NC, USA). General Linear Model was used to examine the differences between sires. The outcome measured was pregnancy rate to fixed-time AI. Variables included in the model were sire (1–3), location (1–4), treatment (Ovsynch-CIDR and CO-Synch-CIDR), age of the dam (2, 3–6 years, ≥7 years), body condition score (≤4, 5–6, ≥7) and all possible two way interactions. The P value was set at <0.05 for inclusion and >0.1 for exclusion. However, appropriate variables were retained in the model. Pregnancy rates and 95% confidence intervals are given in Table 1. Fixed-time AI pregnancy rates between sires within the treatment groups and sires within farms were compared using least square means (Tables 2 and 3). Sire differences in the AI pregnancy rate for cows in Selectsynch-CIDR group were analyzed using chi-square test (Table 4). 3. Results The results indicated that there was no difference in the fixed-time AI pregnancy rate between Ovsynch-CIDR (54.4%; 690/1269) and CO-Synch-CIDR (52.2%; 313/599) groups (P > 0.05). However, there were differences in the fixed-time AI pregnancy rates between sires (Table 1). Cows inseminated with the frozen semen from Sire 2 had lesser pregnancy rates compared to Sire 3 (P < 0.01; Table 1). No differences in the fixed-time AI pregnancy rates were found among locations, body condition scores at initiation of synchronization program and ages of the dam (P > 0.1; Table 1). Significant interactions for sire × treatment and sire × location were observed (P < 0.05).

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Table 1 Effects of farm, synchronization program, sire, body condition score, age on the fixed-time AI pregnancy outcome in beef cows Variablea

Level

Location

1 2 3 4

Synchronization program

Ovsynch-CIDR CO-Synch-CIDR

Sire

1 2 3

Body condition score

≤4 5–6 ≥7

457 1223 188

51.4 (45.2, 57.6) 52.2 (47.9, 56.4) 56.4 (48.3, 64.4)

Age

2 3–6 ≥7

914 670 284

51.2 (44.8, 57.6) 53.5 (48.3, 58.8) 55.2 (47.8, 62.7)

N

PR (95% CL)

237 396 333 902

52.3 (43.3, 61.2) 50.9 (43.1, 58.7) 57.6 (49.2, 66.1) 52.5 (46.9, 58.1)

1269 599

54.4 (46.2, 58.3) 52.2 (50.3, 58.5)

652 446 770

53.2 (47.2, 59.3) ab 48.1 (40.4, 55.8) a 58.7 (53.4, 64.0) b

Different letters (a and b) within variable were significant, P < 0.05. N: sample size; PR: pregnancy rate. a Accounted for sire × synchronization program and sire × farm interactions.

Table 2 Effect of sire (N = 3) on the fixed-time AI pregnancy outcome in Ovsynch-CIDR and CO-Synch-CIDR synchronization program in beef cows (N = 1376) Sire 1

Sire 2

Sire 3

Total

N

PR

N

PR

N

PR

N

PR

Ovsynch-CIDR CO-Synch-CIDR

452 200

54.7 ab 51.7 ab

322 124

48.1 a 48.0 a

495 275

60.3 b 57.0 b

1269 599

54.4 52.2

Total

652

53.2 ab

446

48.1 a

770

58.7 b

1868

53.3

Different letters (a and b) within the row are different (P < 0.05). PR: pregnancy rate.

Table 3 Effect of sire (N = 3) on the fixed-time AI pregnancy outcome within farms in beef cows (N = 1376) Sire 1

Sire 2

Sire 3

Total

N

PR

N

PR

N

PR

Location 1 Location 2 Location 3 Location 4

54 208 92 298

49.6 ab 52.0 ab 55.4 a 55.8 a

50 44 103 249

46.7 a 40.5 a 51.8 a 53.5 a

133 144 138 355

62.1 b 58.8 b 59.4 a 48.5 a

237 396 333 902

52.8 50.9 57.6 52.5

Total

652

53.2 ab

446

48.1 a

770

58.7 b

1868

53.3

Different letters (a and b) within the row are different (P < 0.05). PR: pregnancy rate.

N

PR

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Table 4 Effect of sire (N = 3) on the AI pregnancy outcome in Selectsynch-CIDR programa in beef cows (N = 316) Sire 1 N PR

114 58.8

Sire 2 N PR

63 50.1

Sire 3 N PR

139 55.4

Total N PR

316 55.7

PR: pregnancy rate. a Cows showed estrus observed by activated Kamar on day 9 before 1500 h.

In both the Ovsynch-CIDR and CO-Synch-CIDR groups, Sire 2 had a significantly lesser fixedtime AI pregnancy rates compared to Sire 3 (Table 2). In two out of four locations, Sire 2 had lesser fixed-time AI pregnancy rates compared to Sire 3 (P < 0.05; Table 3). No sire differences in AI pregnancy rate for cows in Selectsynch-CIDR group (P > 0.1; Table 4). 4. Discussion The present study evaluated the sire effect on pregnancy outcome in progesterone based Ovsynch and CO-Synch fixed-time AI programs. The results indicate that there was no difference in the fixed-time AI pregnancy rate between Ovsynch-CIDR (54.4%; 690/1269) and CO-SynchCIDR (52.2%; 313/599) groups (P > 0.10). Geary et al. (2001) compared Ovsynch and CO-Synch programs with or without calf removal and concluded no differences in the conception rate. Also, Martinez et al. (2002) compared pregnancy rates between Ovsynch and CO-Synch in conjunction with progestin in beef heifers and cows concluded no difference in cows, which is consistent with the present study. In contrast, in a previous study it was concluded that conception rate among Ovsynch treated cows was greater compared to CO-Synch treated cows (Geary and Whittier, 1998a). In the present study, over-all fixed-time AI pregnancy rate for Sire 2 was less compared to Sire 3 (48.1% versus 58.7%). Sire 2 had a significantly lesser fixed-time pregnancy rate compared to Sire 3 in both Ovsynch-CIDR and CO-Synch-CIDR groups. It should be noted that cows in both groups that were inseminated before 1500 h on day 9 were excluded from the fixed-time AI analysis to remove bias from early bred cows. Ovarian follicular wave synchronization using GnRH-PGF2␣ (Ovsynch and CO-Synch) has been studied by various research groups (Pursley et al., 1995, 1998; Geary and Whittier, 1998a; Geary et al., 1998b, 2001; Moreira et al., 2000; Martinez et al., 2002; DeJarnette et al., 2004). Pursley et al. (1995) reported that cows ovulate between 24 and 32 h after the second GnRH injection of the Ovsynch protocol. It has also been estimated that the viability of sperm in the female tract is 24–30 h (Lamb et al., 2001). Therefore, in fixed-time AI programs where GnRH is administered before or at the time of insemination, it is probable that an asynchrony between ovulation and arrival of viable sperm capable of fertilization might result in decreased pregnancy rates.

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Contributing factors for decreased synchronized pregnancy rates in beef cows that are subjected to these protocols were asynchrony of follicle wave emergence, premature estrus and/or ovulation, ovulation from smaller sized follicles resulting in low lifespan and reduced function of corpus luteum (Vasconcelos et al., 2001; Hiers et al., 2003; Peters and Pursley, 2003). The contributing factors from bulls might be differences in post-thaw sperm viability, progression of spermatozoa in the female internal genital tract and the resultant sperm reservoir, capacitation, acrosome reaction and fertilizing capacity (Januskauskas et al., 1999; Hunter, 2003; Phillips et al., 2004; Rodr´ıguez-Mart´ınez et al., 2005). Short lifespan of the male and female gametes in the female tract necessitate accurate timing of artificial insemination. In cows, delayed ovulation following estrus minimizes the chances of successful fertilization due to the short fertile lifespan of bovine gametes (Dransfield et al., 1998; Nebel et al., 2000). Studies reported wide variation in estrus to ovulation intervals among individual cows or heifers. In the present study, timing of PGF2␣ to AI interval was 65.8 ± 2.3 h for Ovsynch-CIDR group and 63.2 ± 4.2 h for CO-Synch-CIDR group. No significant differences were observed in the fixed-time AI pregnancy rate between Ovsynch-CIDR group and CO-SynchCIDR group. Also, in the present study, no sire differences were observed in the AI pregnancy rate for cows in Selectsynch-CIDR group. According to Walker et al. (1996), the mean estrus to ovulation intervals and ranges were similar for cows exhibiting spontaneous estrus and for those in which estrus was induced by PGF2␣ might be the possible reason for no differences in pregnancy rates. Pursley et al. (1998) reported that cows inseminated at the time of second injection of GnRH (0 h), approximately 24–32 h before ovulation, had the least pregnancy loss compared with cows inseminated 8, 16, 24 or 32 h after the second injection of GnRH. However, in this study sire differences were observed in the fixed-time AI pregnancy rate for both Ovsynch-CIDR and COSynch-CIDR protocols. Bovine seminal plasma binding protein PDC-109, enables sperm binding to oviductal epithelium thus promoting the formation of the sperm reservoir and plays a crucial role in sperm capacitation (Gwathmey et al., 2003; Hunter and Rodr´ıguez-Mart´ınez, 2004). A study by Thundathil et al. (1999) concluded that the proportion of uncapacitated spermatozoa in frozen thawed sperm varies among bulls and fertility is positively correlated with the amount of uncapacitated spermatozoa after thawing. The sperm reservoir serves to maintain the fertility of sperm until ovulation by regulating capacitation and preventing polyspermy. A recent study by Rodr´ıguez-Mart´ınez et al. (2005) in boars concluded that the numbers of capacitated spermatozoa available at any time varies at the fertilization site. Because the capacitated sperm lifespan is very short, there is a need for continuous release of sperm from the sperm reservoir. Rodr´ıguez-Mart´ınez et al. (2005) also indicated that there is a diverse individual response to capacitation by the spermatozoa in the tubal sperm reservoir. This determines the presence of spermatozoa during different stages of capacitation and sperm viability before ovulation thus increasing the odds of fertilization. The lifespan of the oocyte is a determining factor for successful fertilization, which means the oocyte is waiting for the arrival of eligible sperm. If the oocyte is aged before the arrival of the capable sperm cells then failure of fertilization and or embryonic development may results. In this scenario, it is possible that the capacitation suppressing factors (decapacitating factors) play a negative role by preventing a supply of capacitated sperm in a timely manner. Even though suppression of capacitation is an essential storage strategy, it might play a role in the asynchrony between ovulation and arrival of capable sperm. In the present study, no differences in the PR for fixed-time AI among locations were observed (P > 0.05). However, there was a sire × location interaction observed (P < 0.05). Sire 2 had lesser pregnancy compared to Sire 3 in two of four locations. This indicates that other factors like

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environment and inseminator might play a role. The effect of inseminator on the PR within farm was not different (P > 0.1; not shown). In summary, Sire 2 had poorer pregnancy rate following progesterone based synchronization Ovsynch and CO-Synch programs compared to Sire 3. In twp of four locations Sire 2 had a lesser pregnancy rate compared to Sire 3. No sire differences were observed in AI pregnancy for cows in Selectsynch-CIDR group. In conclusion, evidence in the present study suggest that there are differences in sire fertility when they were used in fixed-time AI protocols, possibly due to the sire differences in sperm capacitation process. Further studies are needed to investigate association of the sire differences in fixed-time AI protocols with sire differences in the sperm capacitation process. Acknowledgements The authors acknowledge staff of Virginia Department of Corrections, Virginia, USA and Select Sire Power Inc., Rocky Mount, VA, USA for their participation and support for this study. References Barth, A.D., 1993. Factors affecting fertility with artificial insemination. Vet. Clin. N. Am. Food Anim. Pract. 9, 275–289. Dalton, J.C., Nadir, S., Bame, J.H., Noftsinger, M., Saacke, R.G., 2000. The effect of tome of artificial insemination on fertilization status and embryo quality in superovulated cows. J. Anim. Sci. 78, 2081–2085. Dalton, J.C., Nadir, S., Bame, J.H., Noftsinger, M., Nebel, R.L., Saacke, R.G., 2001. Effect of time of insemination on number of accessory sperm, fertilization rate, and embryo quality in non lactating dairy cattle. J. Dairy Sci. 84, 2413–2418. DeJarnette, J.M., Marshall, C.E., Lenz, R.W., Monke, D.R., Ayars, W.H., Sattler, C.G., 2004. Sustaining the fertility of artificially inseminated diary cattle: the role of the artificial insemination industry. J. Dairy Sci. (Suppl.) 87, E93–E104. Dransfield, M.B.G., Nebel, R.L., Pearson, R.E., Warnick, L.D., 1998. Timing of insemination for dairy cows identified in estrus by a radiotelemetric estrus detection system. J. Dairy Sci. 81, 1874–1882. Geary, T.W., Whittier, J.C., 1998a. Effects of a timed insemination following synchronization of ovulation using the Ovsynch or CO-Synch protocol in beef cows. Proc. Anim. Sci. 14, 217–220. Geary, T.W., Whittier, J.C., Downing, E.R., LeFevre, D.G., Silcox, R.W., Holland, M.D., 1998b. Pregnancy rates of postpartum beef cows that were synchronized using Syncro-Mate-B or the Ovsynch protocol. J. Anim. Sci. 76, 1523–1527. Geary, T.W., Whittier, J.C., Hallford, D.M., MacNeil, M.D., 2001. Calf removal improves conception rates to the Ovsynch and Co-Synch protocols. J. Anim. Sci. 79, 1–4. Gwathmey, T.M., Ignotz, G.G., Suarez, S.S., 2003. PDC-109 (BSP-A1/A2) promotes bull sperm binding to oviductal epithelium in vitro and may be involved in forming the oviductal sperm reservoir. Biol. Reprod. 69, 809–815. Hiers, E.A., Barthle, C.R., Dahms, M.K.V., Portillo, G.E., Bridges, G.A., Rae, D.O., Thatcher, W.W., Yelich, J.V., 2003. Synchronization of Bos indicus × Bos taurus cows for timed artificial insemination using gonadotropin-releasing hormone plus prostaglandin F2␣ in combination with melengestrol acetate. J. Anim. Sci. 81, 830–835. Hunter, R.H.F., 2003. Refelctions upon sperm-endosalpingeal and sperm-zona pellucida interactions in vivo and in vitro. Reprod. Domest. Anim. 38, 147–154. Hunter, R.H.F., Rodr´ıguez-Mart´ınez, H., 2004. Capacitation of mammalian spermatozoa in vivo, with a specific focus on events in the fallopian tubes. Mol. Reprod. Dev. 67, 243–250. Januskauskas, A., Gil, J., Soderquist, L., Haard, M.G., Haard, M.C., Johannisson, A., Rodr´ıguez-Mart´ınez, H., 1999. Effect of cooling rates on post-thaw sperm motility, membrane integrity, capacitation status and fertility of dairy bull semen used for artificial insemination in Sweden. Theriogenology 52, 641–658. Lamb, G.C., Stevenson, J.S., Kesler, D.J., Garverick, H.A., Brown, D.R., Salfen, B.E., 2001. Inclusion of an intravaginal progesterone insert plus GnRH and prostaglandin F2a for ovulation control in postpartum suckled beef cows. J. Anim. Sci. 79, 2253–2259. Macmillan, K.L., Watson, J.D., 1975. Fertility differences between groups of sires relative to the stage of oestrus at the time of insemination. Anim. Prod. 21, 243–249. Martinez, M.F., Kastelic, J.P., Adams, G.P., Cook, B., Olson, W.O., Mapletoft, R.J., 2002. The use of progestins in regimens for fixed-time artificial insemination in beef cattle. Theriogenology 57, 1049–1059.

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