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Administration of eCG on Day 6 postpartum could enhance reproductive performance of Holstein dairy cows
Animal Reproduction Science 138 (2013) 159–162
Contents lists available at SciVerse ScienceDirect
Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci
Administration of eCG on Day 6 postpartum could enhance reproductive performance of Holstein dairy cows M. Vojgani, V. Akbarinejad, A. Niasari-Naslaji ∗ Department of Theriogenology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
a r t i c l e
i n f o
Article history: Received 9 October 2012 Received in revised form 24 February 2013 Accepted 1 March 2013 Available online 14 March 2013 Keywords: Dairy cows Postpartum eCG Reproductive performance
a b s t r a c t Injection of eCG on Day 6 postpartum could enhance early resumption of ovarian activity in Holstein dairy cows. The present study was conducted to investigate the effects of eCG treatment on Day 6 postpartum on reproductive performance of Holstein dairy cows. Holstein dairy cows (n = 420) were randomly assigned to two groups. Cows in eCG-treated group (n = 220) received an intramuscular injection of eCG (500 IU Folligon® ) on Day 6 postpartum, while cows in the Control group (n = 200) received no treatment. Estrus expression was observed thrice daily, and AI was carried out 12 hours after standing estrus. Data were analyzed using GLM and Genmod procedures, and survival analysis. Days to first service decreased in the eCG-treated (74.4 ± 1.76 days) compared to the Control (84.2 ± 2.79 days) group (P = 0.008). Calving to conception interval was shorter in eCG-treated (103.9 ± 3.14 days) vs Control (130.3 ± 5.70 days) group (P = 0.0006). Cows treated with eCG were inseminated and conceived earlier than untreated cows (P < 0.05). In conclusion, injection of eCG on Day 6 postpartum improved reproductive performance in Holstein dairy cows. © 2013 Elsevier B.V. All rights reserved.
1. Introduction Decline in reproductive efficiency is a ubiquitous problem in modern dairy industry (Beam and Butler, 1999; Lucy, 2001; Macmillan et al., 1996; Roche et al., 2000; Royal et al., 2000), resulting in economic disadvantages for dairy farms (Meadows et al., 2005; Plaizier et al., 1997; Schmidt, 1989). The percentage of postpartum anestrous cows has increased over the last decades (LeBlanc, 2010; Lucy, 2001; McDougall, 2006; Stevenson, 2000). The average interval to the first ovulation has become prolonged and approximately 20% of dairy cows became anestrous before the beginning of voluntary waiting period (Gümen et al., 2003; Moreira et al., 2001; Sakaguchi et al., 2004). Anestrous cows had lower conception rates (Gümen et al., 2003;
∗ Corresponding author at: P.O. Box: 14155-6453, Tehran, Iran. Tel.: +98 21 6111 7136; fax: +98 21 6693 3222. E-mail addresses: [email protected], [email protected] (A. Niasari-Naslaji). 0378-4320/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.anireprosci.2013.03.003
Kawashima et al., 2006), delayed days to the first service and longer calving to conception interval (Kawashima et al., 2006; Walsh et al., 2007) compared to cyclic cows. Therefore, early resumption of postpartum ovarian function and commencement of estrous cycles prior to the first service could improve the first service conception rates and decrease calving to conception interval (Shrestha et al., 2004; Stevenson and Call, 1983; Thatcher and Wilcox, 1973). Postpartum anovulatory anestrus in dairy cows is not due to the absence of a dominant follicle, but rather the failure of dominant follicle to ovulate (Roche et al., 1998). Although a new follicular wave commences about 5–7 days after parturition (Beam and Butler, 1997; Beam and Butler, 1998), the newly emerged follicle, reaching to large size by Day 10 postpartum (Savio et al., 1990), may experience ovulation, cystic degeneration or atresia (Beam and Butler, 1999; Roche et al., 2000; Sakaguchi et al., 2004). More recently, we have demonstrated that the administration of eCG on Day 6 postpartum could enhance follicle growth and ovulation in the first wave dominant follicle,
M. Vojgani et al. / Animal Reproduction Science 138 (2013) 159–162
and reduce the interval from calving to the first ovulation to less than 20 days (Rostami et al., 2011). Moreover, the second and third ovulation occurred earlier in eCG-treated compared to the control cows (Rostami et al., 2011). The purpose of this study was to investigate the effect of injecting eCG on Day 6 postpartum on fertility parameters of postpartum dairy cows. 2. Materials and methods 2.1. Location and animals
Proportion of cows not inseminated
160
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
eCG Control
0
50
100
150
200
250
300
Days in milk
This study was conducted at a commercial dairy farm with 1200 milking cows located in Varamin county, Tehran province, Iran (Latitude: 35◦ 46 N; Longitude: 51◦ 65 E; Altitude: 1200 m). Out of 533 Holstein cows that calved between June and November 2011, 420 cows were enrolled in this study. The enrolled cows did not have any puerperal disorders such as dystocia (incidence: 16.5%), twinning (incidence: 2.3%) and retained placenta (incidence: 13.3%), and any other productive and/or reproductive disorders including metritis (incidence: 11.3%), clinical mastitis (incidence: 3.6%) and lameness (incidence: 4.5%). Cows were housed in free stall barns and received a total mixed ration (NRC, 2001). Cows were milked thrice daily and had a herd average milk production of 9800 kg per lactation. 2.2. Experimental design Cows (n = 420) were randomly assigned to two experimental groups. Cows in eCG group (n = 220; primiparous cows, n = 71; multiparous cows, n = 149) received an i.m. injection of eCG (500 IU; Folligon® ; Intervet, Holland) on Day 6 postpartum. Cows in the Control group (n = 200; primiparous cows, n = 80; multiparous cows, n = 120) received no treatment. After termination of voluntary waiting period (VWP ≥ 42 days), cows were inseminated 12 hours after standing estrus. Estrus detection was performed thrice daily (5:00, 14:00, 20:00) by visual observation for at least 30 minutes each time. All inseminations were conducted by the same technician and pregnancy diagnosis was performed, thrice weekly, between Days 40 and 45 after AI by transrectal palpation. 2.3. Statistical analysis Days to first service, service per conception, and calving to conception interval were analyzed using Proc GLM including treatment and parity as main effects and milk production as covariate in the model. First service conception rate was analyzed using Proc Genmod including Logit in the model; treatment, parity, sperm and milk production were considered as covariates. The proportion of repeat breeder cows (cows failed to conceive after 3 services) was analyzed using Proc Genmod including Logit in the model; treatment, parity and milk production were considered as covariates. Survival analyses (Proc Lifetest) were used to evaluate the effects of treatment and parity on interval to first service and interval to conception. Milk production was considered as a covariate. For intervals from parturition to first insemination and conception,
Fig. 1. The proportion of cows not inseminated over time postpartum (survival analyses). Survival curves were presented for cows in eCG (received 500 IU eCG on day 6 postpartum) and Control (received no treatment) groups.
the survival analysis regressed the proportion of cows that were not inseminated and conceived, respectively. Data for cattle that were never inseminated and conceived were included in the statistical analyses as censored observations. Differences between the survival curves were tested with the Wilcoxon test. The effects of treatment and parity on interval to first insemination and conception were analyzed using Proc Phreg. All analyses were conducted in SAS (SAS, 2008). Data are presented as means ± standard error of the mean or percentages. 3. Results Fifteen animals (eCG-treated: 8 animals; Control: 7 animals) were excluded from this study due to health problems such as lameness, persistent mastitis and accidental injuries. Days to first service was lower in eCG-treated (74.4 ± 1.76) than Control group (84.2 ± 2.79; P = 0.008; Table 1). Survival curves were different between eCGtreated and untreated cows in terms of the interval to first service (P = 0.009; Fig. 1); however, survival curves were not different between primiparous and multiparous cows (P > 0.05). Calving to conception interval was significantly lower in eCG-treated (103.9 ± 3.14) than that in Control group (130.3 ± 5.70; P = 0.0006; Table 1). There was an effect of treatment on the survival curves with regard to interval to conception (P < 0.0001; Fig. 2), but there was no effect of parity on the survival curves (P > 0.05). First service conception rates, proportion of repeat breeders and services per conception were not different between two groups (P > 0.05). There was no effect of parity and interaction of parity by treatment on days to first service, first service conception rates, proportion of repeat breeders, services per conception and calving to conception interval (P > 0.05). In addition, there was no influence of sperm on the first service conception rates (P > 0.05). 4. Discussion According to the working hypothesis of the present study, eCG treatment on Day 6 postpartum could enhance the reproductive performance in Holstein dairy cows. More
M. Vojgani et al. / Animal Reproduction Science 138 (2013) 159–162
161
Table 1 Performance of dairy cows with and without eCG on day 6 postpartum. Data were presented as mean ± SEM and percentages. Parameter
DFS (day) FSCR (%) RB (%) SPC CCI (day)
eCG
Control
P-value
Primiparous cows (n = 69)
Multiparous cows (n = 143)
Total (n = 212)
Primiparous cows (n = 78)
Multiparous cows (n = 115)
Total (n = 193)
Trt
Pa
Trt*Pa
76.2 ± 3.13 59.4 (41/69) 13.0 (9/69) 1.9 ± 0.17 101.9 ± 5.03
73.6 ± 2.12 47.6 (68/143) 11.9 (17/143) 2.1 ± 0.11 104.9 ± 3.98
74.4 ± 1.76 51.4 (109/212) 12.3 (26/212) 2.0 ± 0.09 103.9 ± 3.14
86.6 ± 4.15 64.1 (50/78) 14.1 (11/78) 1.8 ± 0.17 122.9 ± 8.38
82.6 ± 3.74 39.1 (45/115) 21.7 (25/115) 2.4 ± 0.15 135.2 ± 7.68
84.2 ± 2.79 49.2 (95/193) 18.7 (36/193) 2.2 ± 0.11 130.3 ± 5.70
0.008 0.149 0.903 0.516 0.0006
0.433 0.301 0.491 0.060 0.476
0.769 0.117 0.409 0.408 0.562
Trt: treatment; Pa: parity; DFS: Days to first service; FSCR: first service conception rate; RB: repeat breeder cows; SPC: service per conception; CCI: calving to conception interval.
Proportion of cows not conceived
recently, we have demonstrated that eCG administration on Day 6 postpartum could enhance early resumption of ovarian activity in Holstein dairy cows (Rostami et al., 2011). It is well documented that cows with early resumption of ovarian function have higher fertility (Galvão et al., 2010; Santos et al., 2009; Stevenson and Call, 1983; Thatcher and Wilcox, 1973). Indeed, minimizing the interval from calving to the first ovulation provides ample time for completion of multiple ovarian cycles (more luteal phases) prior to insemination, which, in turn, improves reproductive efficiency of dairy cows (Kawashima et al., 2006; Stevenson and Call, 1983; Thatcher and Wilcox, 1973). In the present study, early administration of eCG postpartum advanced days to first service in dairy cows. Likewise, enhancement of the initiation of postpartum luteal activity shortened the interval from calving to the first service (Darwash et al., 2001). Kawashima et al. (2006) pointed out that cows ovulating within 3 weeks postpartum had shorter days to first service than anovular cows. In addition, in herds in which AI was based on estrus detection, anestrous cows had delayed days to first service compared to cyclic cows (Horan et al., 2005; Walsh et al., 2007). Treatment of cows with eCG 6 days after parturition enhanced ovarian follicular growth and early ovulation postpartum (Rostami et al., 2011). Moreover, eCG substantially increased the proportion of cows that ovulated by Day 20 postpartum, and also decreased the interval from calving to the second and third ovulation (Rostami et al., 2011).
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
eCG Control
0
50
100
150
200
250
300
350
400
450
Days in milk Fig. 2. The proportion of cows not conceived over time postpartum (survival analyses). Survival curves were presented for cows in eCG (received 500 IU eCG on day 6 postpartum) and Control (received no treatment) groups.
In the present study, eCG treatment on Day 6 postpartum enhanced reproductive performance in dairy cows. Treatment with eCG on Day 14 postpartum has been reported to increase plasma estradiol concentrations (Sheldon and Dobson, 2000). Availability of circulating estradiol could accelerate uterine involution through reducing uterine size and increasing uterine tone (Hussain, 1989) and benefit to the uterine defense mechanisms (Rowson et al., 1953). Estradiol also has a positive effect on the ability of the endometrium to secrete PGF2 ␣ in response to oxytocin, but the uterus must have been exposed to sufficient amount of progesterone during previous luteal phase (Frazer, 2005). Administration of eCG on Day 6 postpartum advanced elevation of progesterone following parturition (Rostami et al., 2011). It is documented that cows experiencing ovulation and subsequent elevation of progesterone as early as 21 days postpartum had lower prevalence of subclinical endometritis (Galvão et al., 2010), which could compromise fertility of dairy cows (Galvão et al., 2009; Gilbert et al., 2005; Kasimanickam et al., 2004). Greater fertility could be expected for cows following early resumption of ovarian activity compared with cows considered noncyclic (having progesterone concentrations <1 ng/ml) by 49 days postpartum (Galvão et al., 2010). Some aspects of neutrophils function, as the main uterine defense mechanism against bacterial infection (Hussain, 1989; Lewis, 2003; Herath et al., 2006), were significantly enhanced in the presence of high peripheral plasma progesterone concentrations (Subandrio et al., 2000). The migratory response of neutrophils into the uterine lumen is greatest under progesterone dominance but their phagocytic activity is higher under estrogen dominance (BonDurant, 1999; Dhaliwal et al., 2001). We have also demonstrated that short-term exposure to progesterone (for 7 days) may enhance reproductive performance of dairy cows with mild clinical endometritis (Salasel et al., 2008). Therefore, improved fertility in eCG-treated cows could be due to more appropriate uterine environment provided by enhanced ovarian function leading to multiple ovarian cycles prior to voluntary waiting period. Finally, advancement of days to first service and improvement of fertility led to reduced calving to conception interval in eCG-treated cows compared to untreated cows. Similarly, shorter calving to conception interval has been reported in cyclic cows compared to noncyclic cows in other studies (Kawashima et al., 2006; Shrestha et al., 2004; Walsh et al., 2007).
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5. Conclusion In conclusion, the present study substantiated that early resumption of ovarian activity using eCG on Day 6 postpartum could advance days to first service and enhance fertility, resulting in considerable decrease in calving to conception interval in Holstein dairy cows. Acknowledgements The authors wish to express their great appreciations to Dr. A. Gerami and Dr. H. A. Seifi for their kind assistance in statistical analysis. References Beam, S.W., Butler, W.R., 1997. Energy balance and ovarian follicle development prior to the first ovulation postpartum in dairy cows receiving three levels of dietary fat. Biol. Reprod. 56, 132–142. Beam, S.W., Butler, W.R., 1998. Energy balance, metabolic hormones, and early postpartum follicular development in dairy cows fed prilled lipid. J. Dairy Sci. 81, 121–131. Beam, S.W., Butler, W.R., 1999. Effects of energy balance on follicular development and first ovulation in postpartum dairy cows. J. Reprod. Fertil. Suppl. 54, 411–424. BonDurant, R.H., 1999. Inflammation in the bovine reproductive tract. J. Dairy Sci. 82 (Suppl. 2), 101–110. Darwash, A.O., Lamming, G.E., Royal, M.D., 2001. A protocol for initiating oestrus and ovulation early postpartum in dairy cows. Anim. Sci. 72, 539–546. Dhaliwal, G.S., Murray, R.D., Woldehiwet, Z., 2001. Some aspects of immunology of the bovine uterus related to treatments for endometritis. Anim. Reprod. Sci. 67, 135–152. Frazer, G.S., 2005. A rational basis for therapy in the sick postpartum cow. Vet. Clin. North Am. Food Anim. Pract. 21, 523–568. Galvão, K.N., Fraiblat, M., Butler, W.R., Brittin, S.B., Guard, C.L., Gilbert, R.O., 2010. Effect of early postpartum ovulation on fertility in dairy cows. Reprod. Domest. Anim. 45, 207–211. Galvão, K.N., Frajblat, M., Brittin, S.B., Butler, W.R., Guard, C.L., Gilbert, R.O., 2009. Effect of prostaglandin F2␣ on subclinical endometritis and fertility in dairy cow. J. Dairy Sci. 92, 4906–4913. Gilbert, R.O., Shin, S.T., Guard, C.L., Erb, H.N., Frajblat, M., 2005. Prevalence of endometritis and its effects on reproductive performance of dairy cows. Theriogenology 64, 1879–1888. Gümen, A., Guenther, J.N., Wiltbank, M.C., 2003. Follicular size and response to Ovsynch versus detection of estrus in anovular and ovular lactating dairy cows. J. Dairy Sci. 86, 3184–3194. Herath, S., Dobson, H., Bryant, C.E., Sheldon, I.M., 2006. Use of the cow as a large animal model of uterine infection and immunity. J. Reprod. Immunol. 69, 13–22. Horan, B., Mee, J.F., O’Connor, P., Rath, M., Dillon, P., 2005. The effect of strain of Holstein-Friesian cow and feeding system on postpartum ovarian function, animal production and conception rate to first service. Theriogenology 63, 950–971. Hussain, A.M., 1989. Bovine uterine defence mechanisms: a review. J. Vet. Med. 36, 641–651. Kasimanickam, R., Duffield, T.F., Foster, R.A., Gartley, C.J., Leslie, K.E., Walton, J.S., Johnson, W.H., 2004. Endometrial cytology and ultrasonography for the detection of subclinical endometritis in postpartum dairy cows. Theriogenology 62, 9–23. Kawashima, C., Kaneko, E., Montoya, C.A., Matsui, M., Yamagishi, N., Matsunaga, N., Ishii, M., Kida, K., Miyake, Y-I., Miyamoto, A., 2006. Relationship between the first ovulation within three weeks postpartum and subsequent ovarian cycles and fertility in high producing dairy cows. J. Reprod. Dev. 52, 479–486. LeBlanc, S., 2010. Assessing the association of the level of milk production with reproductive performance. J. Reprod. Dev. Suppl. 56, 1–7.
Lewis, G.S., 2003. Steroidal regulation of uterine resistance to bacterial infection in livestock. Reprod. Biol. Endocrinol. 1, 117. Lucy, M.C., 2001. Reproductive loss in high-producing dairy cattle: where will it end? J. Dairy Sci. 84, 1277–1293. Macmillan, K.L., Lean, I.J., Westwood, C.T., 1996. The effects of lactation on the fertility of dairy cows. Aust. Vet. J. 73, 141–147. McDougall, S., 2006. Reproduction performance and management of dairy cattle. J. Reprod. Dev. 52, 185–194. Meadows, C., Rajala-Schultz, P.J., Frazer, G.S., 2005. A spreadsheet-based model demonstrating the nonuniform economic effects of varying reproductive performance in Ohio dairy herds. J. Dairy Sci. 88, 1244–1254. Moreira, F., Orlandi, C., Risco, C.A., Mattos, R., Lopes, F., Thatcher, W.W., 2001. Effects of presynchronization and bovine somatotropin on pregnancy rates to a timed artificial insemination protocol in lactating dairy cows. J. Dairy Sci. 84, 1646–1659. NRC, 2001. Nutrient Requirements of Dairy Cattle, seventh ed. National Academy Press, Washington D.C., USA. Plaizier, J.C., King, G.J., Dekkers, J.C., Lissemore, K., 1997. Estimation of economic values of indices for reproductive performance in dairy herds using computer simulation. J. Dairy Sci. 80, 2775–2783. Roche, J.F., Mackey, D., Diskin, M.D., 2000. Reproductive management of postpartum cows. Anim. Reprod. Sci. 60–61, 703–712. Roche, J.F., Mihm, M., Diskin, M.G., Ireland, J.J., 1998. A review of regulation of follicle growth in cattle. J. Anim. Sci. 76, 16–29. Rostami, B., Niasari-Naslaji, A., Vojgani, M., Nikjou, D., Amanlou, H., Gerami, A., 2011. Effect of eCG on early resumption of ovarian activity in postpartum dairy cows. Anim. Reprod. Sci. 128, 100–106. Rowson, L.E.A., Lamming, G.E., Fry, R.M., 1953. The relationship between ovarian hormones and uterine infection. Vet. Rec. 65, 335–341. Royal, M.D., Darwash, A.O., Flint, A.P.F., Webb, R., Woolliams, J.A., Lamming, G.E., 2000. Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility. Anim. Sci. 70, 487–502. Sakaguchi, M., Sasamoto, Y., Suzuki, T., Takahashi, Y., Yamada, Y., 2004. Postpartum ovarian follicular dynamics and estrous activity in lactating dairy cows. J. Dairy Sci. 87, 2114–2121. Salasel, B., Bolourchi, M., Hovareshti, P., Niasari-Naslaji, A., Gerami, A., 2008. Effectiveness of short-term progesterone, GnRH and Ceftiofur for treating mild clinical endometritis in lactating dairy cow with low plasma progesterone concentrations. 15th World Buiatrics Congress, Budapest, Hungary, pp. 191. Santos, J.E.P., Rutigliano, H.M., SáFilho, M.F., 2009. Risk factors for resumption of postpartum estrous cycles and embryonic survival in lactating dairy cows. Anim. Reprod. Sci. 110, 207–221. SAS Institute Inc., 2008. Statistical Analysis System: A User’s Guide, version 9.2. Cary, NC. Savio, J.D., Boland, M.P., Hynes, N., Roche, J.F., 1990. Resumption of follicular activity in the early post-partum period of dairy cows. J. Reprod. Fertil. 88, 569–579. Schmidt, G.H., 1989. Effect of length of calving interval on income over feed and variable costs. J. Dairy Sci. 72, 1605–1611. Sheldon, I.M., Dobson, H., 2000. Effect of administration of eCG to postpartum cows on folliculogenesis in the ovary ipsilateral to the previously gravid uterine horn and uterine involution. J. Reprod. Fertil. 119, 157–163. Shrestha, H.K., Nakao, T., Suzuki, T., Higaki, T., Akita, M., 2004. Effects of abnormal ovarian cycles during pre-service period postpartum on subsequent reproductive performance of high-producing Holstein cows. Theriogenology 61, 1559–1571. Stevenson, J.S., 2000. Are your cows cycling; if not why? Hoard’s Dairyman 145, 202–203. Stevenson, J.S., Call, E.P., 1983. Influence of early estrus, ovulation and insemination on fertility in post partum Holstein cows. Theriogenology 19, 367–375. Subandrio, A.L., Sheldon, I.M., Noakes, D.E., 2000. Peripheral and intrauterine neutrophil function in the cow: the influence of endogenous and exogenous sex steroid hormones. Theriogenology 53, 1591–1608. Thatcher, W.W., Wilcox, C.J., 1973. Postpartum estrus as an indicator of reproductive status in dairy cow. J. Dairy Sci. 56, 608–610. Walsh, R.B., Kelton, D.F., Duffield, T.F., Leslie, K.E., Walton, J.S., LeBlanc, S.J., 2007. Prevalence and risk factors for postpartum anovulatory condition in dairy cows. J. Dairy Sci. 90, 315–324.
Contents lists available at SciVerse ScienceDirect
Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci
Administration of eCG on Day 6 postpartum could enhance reproductive performance of Holstein dairy cows M. Vojgani, V. Akbarinejad, A. Niasari-Naslaji ∗ Department of Theriogenology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
a r t i c l e
i n f o
Article history: Received 9 October 2012 Received in revised form 24 February 2013 Accepted 1 March 2013 Available online 14 March 2013 Keywords: Dairy cows Postpartum eCG Reproductive performance
a b s t r a c t Injection of eCG on Day 6 postpartum could enhance early resumption of ovarian activity in Holstein dairy cows. The present study was conducted to investigate the effects of eCG treatment on Day 6 postpartum on reproductive performance of Holstein dairy cows. Holstein dairy cows (n = 420) were randomly assigned to two groups. Cows in eCG-treated group (n = 220) received an intramuscular injection of eCG (500 IU Folligon® ) on Day 6 postpartum, while cows in the Control group (n = 200) received no treatment. Estrus expression was observed thrice daily, and AI was carried out 12 hours after standing estrus. Data were analyzed using GLM and Genmod procedures, and survival analysis. Days to first service decreased in the eCG-treated (74.4 ± 1.76 days) compared to the Control (84.2 ± 2.79 days) group (P = 0.008). Calving to conception interval was shorter in eCG-treated (103.9 ± 3.14 days) vs Control (130.3 ± 5.70 days) group (P = 0.0006). Cows treated with eCG were inseminated and conceived earlier than untreated cows (P < 0.05). In conclusion, injection of eCG on Day 6 postpartum improved reproductive performance in Holstein dairy cows. © 2013 Elsevier B.V. All rights reserved.
1. Introduction Decline in reproductive efficiency is a ubiquitous problem in modern dairy industry (Beam and Butler, 1999; Lucy, 2001; Macmillan et al., 1996; Roche et al., 2000; Royal et al., 2000), resulting in economic disadvantages for dairy farms (Meadows et al., 2005; Plaizier et al., 1997; Schmidt, 1989). The percentage of postpartum anestrous cows has increased over the last decades (LeBlanc, 2010; Lucy, 2001; McDougall, 2006; Stevenson, 2000). The average interval to the first ovulation has become prolonged and approximately 20% of dairy cows became anestrous before the beginning of voluntary waiting period (Gümen et al., 2003; Moreira et al., 2001; Sakaguchi et al., 2004). Anestrous cows had lower conception rates (Gümen et al., 2003;
∗ Corresponding author at: P.O. Box: 14155-6453, Tehran, Iran. Tel.: +98 21 6111 7136; fax: +98 21 6693 3222. E-mail addresses: [email protected], [email protected] (A. Niasari-Naslaji). 0378-4320/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.anireprosci.2013.03.003
Kawashima et al., 2006), delayed days to the first service and longer calving to conception interval (Kawashima et al., 2006; Walsh et al., 2007) compared to cyclic cows. Therefore, early resumption of postpartum ovarian function and commencement of estrous cycles prior to the first service could improve the first service conception rates and decrease calving to conception interval (Shrestha et al., 2004; Stevenson and Call, 1983; Thatcher and Wilcox, 1973). Postpartum anovulatory anestrus in dairy cows is not due to the absence of a dominant follicle, but rather the failure of dominant follicle to ovulate (Roche et al., 1998). Although a new follicular wave commences about 5–7 days after parturition (Beam and Butler, 1997; Beam and Butler, 1998), the newly emerged follicle, reaching to large size by Day 10 postpartum (Savio et al., 1990), may experience ovulation, cystic degeneration or atresia (Beam and Butler, 1999; Roche et al., 2000; Sakaguchi et al., 2004). More recently, we have demonstrated that the administration of eCG on Day 6 postpartum could enhance follicle growth and ovulation in the first wave dominant follicle,
M. Vojgani et al. / Animal Reproduction Science 138 (2013) 159–162
and reduce the interval from calving to the first ovulation to less than 20 days (Rostami et al., 2011). Moreover, the second and third ovulation occurred earlier in eCG-treated compared to the control cows (Rostami et al., 2011). The purpose of this study was to investigate the effect of injecting eCG on Day 6 postpartum on fertility parameters of postpartum dairy cows. 2. Materials and methods 2.1. Location and animals
Proportion of cows not inseminated
160
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
eCG Control
0
50
100
150
200
250
300
Days in milk
This study was conducted at a commercial dairy farm with 1200 milking cows located in Varamin county, Tehran province, Iran (Latitude: 35◦ 46 N; Longitude: 51◦ 65 E; Altitude: 1200 m). Out of 533 Holstein cows that calved between June and November 2011, 420 cows were enrolled in this study. The enrolled cows did not have any puerperal disorders such as dystocia (incidence: 16.5%), twinning (incidence: 2.3%) and retained placenta (incidence: 13.3%), and any other productive and/or reproductive disorders including metritis (incidence: 11.3%), clinical mastitis (incidence: 3.6%) and lameness (incidence: 4.5%). Cows were housed in free stall barns and received a total mixed ration (NRC, 2001). Cows were milked thrice daily and had a herd average milk production of 9800 kg per lactation. 2.2. Experimental design Cows (n = 420) were randomly assigned to two experimental groups. Cows in eCG group (n = 220; primiparous cows, n = 71; multiparous cows, n = 149) received an i.m. injection of eCG (500 IU; Folligon® ; Intervet, Holland) on Day 6 postpartum. Cows in the Control group (n = 200; primiparous cows, n = 80; multiparous cows, n = 120) received no treatment. After termination of voluntary waiting period (VWP ≥ 42 days), cows were inseminated 12 hours after standing estrus. Estrus detection was performed thrice daily (5:00, 14:00, 20:00) by visual observation for at least 30 minutes each time. All inseminations were conducted by the same technician and pregnancy diagnosis was performed, thrice weekly, between Days 40 and 45 after AI by transrectal palpation. 2.3. Statistical analysis Days to first service, service per conception, and calving to conception interval were analyzed using Proc GLM including treatment and parity as main effects and milk production as covariate in the model. First service conception rate was analyzed using Proc Genmod including Logit in the model; treatment, parity, sperm and milk production were considered as covariates. The proportion of repeat breeder cows (cows failed to conceive after 3 services) was analyzed using Proc Genmod including Logit in the model; treatment, parity and milk production were considered as covariates. Survival analyses (Proc Lifetest) were used to evaluate the effects of treatment and parity on interval to first service and interval to conception. Milk production was considered as a covariate. For intervals from parturition to first insemination and conception,
Fig. 1. The proportion of cows not inseminated over time postpartum (survival analyses). Survival curves were presented for cows in eCG (received 500 IU eCG on day 6 postpartum) and Control (received no treatment) groups.
the survival analysis regressed the proportion of cows that were not inseminated and conceived, respectively. Data for cattle that were never inseminated and conceived were included in the statistical analyses as censored observations. Differences between the survival curves were tested with the Wilcoxon test. The effects of treatment and parity on interval to first insemination and conception were analyzed using Proc Phreg. All analyses were conducted in SAS (SAS, 2008). Data are presented as means ± standard error of the mean or percentages. 3. Results Fifteen animals (eCG-treated: 8 animals; Control: 7 animals) were excluded from this study due to health problems such as lameness, persistent mastitis and accidental injuries. Days to first service was lower in eCG-treated (74.4 ± 1.76) than Control group (84.2 ± 2.79; P = 0.008; Table 1). Survival curves were different between eCGtreated and untreated cows in terms of the interval to first service (P = 0.009; Fig. 1); however, survival curves were not different between primiparous and multiparous cows (P > 0.05). Calving to conception interval was significantly lower in eCG-treated (103.9 ± 3.14) than that in Control group (130.3 ± 5.70; P = 0.0006; Table 1). There was an effect of treatment on the survival curves with regard to interval to conception (P < 0.0001; Fig. 2), but there was no effect of parity on the survival curves (P > 0.05). First service conception rates, proportion of repeat breeders and services per conception were not different between two groups (P > 0.05). There was no effect of parity and interaction of parity by treatment on days to first service, first service conception rates, proportion of repeat breeders, services per conception and calving to conception interval (P > 0.05). In addition, there was no influence of sperm on the first service conception rates (P > 0.05). 4. Discussion According to the working hypothesis of the present study, eCG treatment on Day 6 postpartum could enhance the reproductive performance in Holstein dairy cows. More
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Table 1 Performance of dairy cows with and without eCG on day 6 postpartum. Data were presented as mean ± SEM and percentages. Parameter
DFS (day) FSCR (%) RB (%) SPC CCI (day)
eCG
Control
P-value
Primiparous cows (n = 69)
Multiparous cows (n = 143)
Total (n = 212)
Primiparous cows (n = 78)
Multiparous cows (n = 115)
Total (n = 193)
Trt
Pa
Trt*Pa
76.2 ± 3.13 59.4 (41/69) 13.0 (9/69) 1.9 ± 0.17 101.9 ± 5.03
73.6 ± 2.12 47.6 (68/143) 11.9 (17/143) 2.1 ± 0.11 104.9 ± 3.98
74.4 ± 1.76 51.4 (109/212) 12.3 (26/212) 2.0 ± 0.09 103.9 ± 3.14
86.6 ± 4.15 64.1 (50/78) 14.1 (11/78) 1.8 ± 0.17 122.9 ± 8.38
82.6 ± 3.74 39.1 (45/115) 21.7 (25/115) 2.4 ± 0.15 135.2 ± 7.68
84.2 ± 2.79 49.2 (95/193) 18.7 (36/193) 2.2 ± 0.11 130.3 ± 5.70
0.008 0.149 0.903 0.516 0.0006
0.433 0.301 0.491 0.060 0.476
0.769 0.117 0.409 0.408 0.562
Trt: treatment; Pa: parity; DFS: Days to first service; FSCR: first service conception rate; RB: repeat breeder cows; SPC: service per conception; CCI: calving to conception interval.
Proportion of cows not conceived
recently, we have demonstrated that eCG administration on Day 6 postpartum could enhance early resumption of ovarian activity in Holstein dairy cows (Rostami et al., 2011). It is well documented that cows with early resumption of ovarian function have higher fertility (Galvão et al., 2010; Santos et al., 2009; Stevenson and Call, 1983; Thatcher and Wilcox, 1973). Indeed, minimizing the interval from calving to the first ovulation provides ample time for completion of multiple ovarian cycles (more luteal phases) prior to insemination, which, in turn, improves reproductive efficiency of dairy cows (Kawashima et al., 2006; Stevenson and Call, 1983; Thatcher and Wilcox, 1973). In the present study, early administration of eCG postpartum advanced days to first service in dairy cows. Likewise, enhancement of the initiation of postpartum luteal activity shortened the interval from calving to the first service (Darwash et al., 2001). Kawashima et al. (2006) pointed out that cows ovulating within 3 weeks postpartum had shorter days to first service than anovular cows. In addition, in herds in which AI was based on estrus detection, anestrous cows had delayed days to first service compared to cyclic cows (Horan et al., 2005; Walsh et al., 2007). Treatment of cows with eCG 6 days after parturition enhanced ovarian follicular growth and early ovulation postpartum (Rostami et al., 2011). Moreover, eCG substantially increased the proportion of cows that ovulated by Day 20 postpartum, and also decreased the interval from calving to the second and third ovulation (Rostami et al., 2011).
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
eCG Control
0
50
100
150
200
250
300
350
400
450
Days in milk Fig. 2. The proportion of cows not conceived over time postpartum (survival analyses). Survival curves were presented for cows in eCG (received 500 IU eCG on day 6 postpartum) and Control (received no treatment) groups.
In the present study, eCG treatment on Day 6 postpartum enhanced reproductive performance in dairy cows. Treatment with eCG on Day 14 postpartum has been reported to increase plasma estradiol concentrations (Sheldon and Dobson, 2000). Availability of circulating estradiol could accelerate uterine involution through reducing uterine size and increasing uterine tone (Hussain, 1989) and benefit to the uterine defense mechanisms (Rowson et al., 1953). Estradiol also has a positive effect on the ability of the endometrium to secrete PGF2 ␣ in response to oxytocin, but the uterus must have been exposed to sufficient amount of progesterone during previous luteal phase (Frazer, 2005). Administration of eCG on Day 6 postpartum advanced elevation of progesterone following parturition (Rostami et al., 2011). It is documented that cows experiencing ovulation and subsequent elevation of progesterone as early as 21 days postpartum had lower prevalence of subclinical endometritis (Galvão et al., 2010), which could compromise fertility of dairy cows (Galvão et al., 2009; Gilbert et al., 2005; Kasimanickam et al., 2004). Greater fertility could be expected for cows following early resumption of ovarian activity compared with cows considered noncyclic (having progesterone concentrations <1 ng/ml) by 49 days postpartum (Galvão et al., 2010). Some aspects of neutrophils function, as the main uterine defense mechanism against bacterial infection (Hussain, 1989; Lewis, 2003; Herath et al., 2006), were significantly enhanced in the presence of high peripheral plasma progesterone concentrations (Subandrio et al., 2000). The migratory response of neutrophils into the uterine lumen is greatest under progesterone dominance but their phagocytic activity is higher under estrogen dominance (BonDurant, 1999; Dhaliwal et al., 2001). We have also demonstrated that short-term exposure to progesterone (for 7 days) may enhance reproductive performance of dairy cows with mild clinical endometritis (Salasel et al., 2008). Therefore, improved fertility in eCG-treated cows could be due to more appropriate uterine environment provided by enhanced ovarian function leading to multiple ovarian cycles prior to voluntary waiting period. Finally, advancement of days to first service and improvement of fertility led to reduced calving to conception interval in eCG-treated cows compared to untreated cows. Similarly, shorter calving to conception interval has been reported in cyclic cows compared to noncyclic cows in other studies (Kawashima et al., 2006; Shrestha et al., 2004; Walsh et al., 2007).
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