The Journal of Animal & Plant Sciences, 30(1): 2020, Page: 255-258
ISSN: 1018-7081
Short Communication
FERTILITY OF LACTATING JERSEY X HOLSTEIN-FRIESIAN COWS IN SUBTROPICAL REGION SUBMITTED TO A DOUBLE-OVSYNCH VERSUS OVSYNCH PROTOCOL FOR TIMED ARTIFICIAL INSEMINATION
A. A. Channa1, M. Aleem1, M. A. Jabbar2, H. Monir3 and N. Ahmad1*
1Department of Theriogenology, Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore, 54000, Pakistan; 2Department of Animal Nutrition, Faculty of Animal Production and Technology, University of Veterinary and Animal Sciences, Lahore, 54000, Pakistan; 3Sapphire Dairy Farm, Kasur, Pakistan
*Corresponding author’s E-mail address: nasimahmad@uvas.edu.pk
ABSTRACT
Pre-synchronization prior to Ovsynch protocol is an efficient method to improve ovulation and pregnancy rate in dairy cows. The objective of this study was to define the effect of Double-Ovsynch (DOS; GnRH, PGF2α 7 d later and GnRH 2 d later followed by the OVS protocol with interval of 7 d; timed AI 16 to 24 h after the last GnRH of OVS) and Ovsynch (OVS; GnRH, PGF2α 7 d later and GnRH 2 d later; timed AI 16- 24 h after the last GnRH) protocols on ovulation and pregnancy rate in crossbred dairy cows. The ovulation rate (day 7 post TAI, DOS n = 20 vs. OVS n = 21) and pregnancy rate (day 35 post TAI, DOS n = 125 vs. OVS n = 148) were determined using ultrasonography. Serum concentrations of progesterone on d 7 after the last GnRH of each protocol was determined in the subset of randomly selected cows (DOS n = 10) and (OVS n =10) protocol. The Ovulation rate (OR) was higher (P < 0.05) in DOS as compared to OVS (90% vs. 47%) protocols. Likewise, pregnancies per AI (P/AI) significantly (P<0.05) increased in DOS as compared to OVS (62 % vs. 30%). Mean serum concentrations of progesterone on d 7 remained similar (P > 0.05) between DOS and OVS (8.68 ± 0.78 ng/mL: 8.19 ± 1.85 ng/mL)protocols. It is concluded that DOS compared to OVS yields better ovulation and pregnancy rate in crossbred dairy cows.
Key words: Ovsynch; Double-Ovsynch; Ovulation; Pregnancy; Crossbred cows
INTRODUCTION
Commercial dairy farming with exotic herds comprising of Holstein, Jersey and their crosses, is one of the fast growing industries in tropical and sub-tropical countries. Reproduction, in high milk yielding dairy cows, is the key to profitability. However, estrus detection and estrus expression rate are less and lead to overall lowered fertility and increased calving interval (Washburn et al. 2002,Lopez-Gatius et al. 2005,Wiltbank et al. 2006) . To overcome heat detection in large dairies, estrus and ovulation synchronization protocol (Ovsynch) was developed (Pursley et al. 1995) in United State of America (USA) which had a provision to breed cows at fixed time. The Ovsynch is a hormonal regime in which gonadotropin-releasing hormone (GnRH) and Prostaglandin F2α (PG) are used. GnRH induces ovulation and PG causes luteolysis of the corpus luteum (CL). The fertility though was lower in TAI with that of detected estrus using synch (Tenhagen et al. 2004). The plausible reason for lowered fertility is the variation in the ovulatory response due to the stage of cycle (Vasconcelos et al. 1999) .
The presence of large follicle at the time of 1st GnRH of Ovsynch protocol improves the ovulation and pregnancy rates in dairy cattle (Vasconcelos et al. 1999) . Therefore, prior to the Ovsynch, some pre-synchronization regimes were developed in order to enhance the success of this protocol. This included use of single PG (LeBlanc and Leslie 2003), double PG (Moreira et al. 2001) , G6G (Bello et al. 2006) and Double-Ovsynch (Souza et al. 2008) . The results from the pre synchronization with PG indicated its ineffectiveness to induce cyclicity in an-ovular cows (Moreira et al. 2001) whereas Double-Ovsynch protocol was able to induce cyclicity in acyclic lactating Holstein cows and enhanced ovulation and pregnancy rate of ensuing Ovsynch protocol (Astiz and Fargas 2013). The information regarding the success of the double Ovsynch protocol in crossbred cows in sub-tropical large dairy herds is lacking. Therefore, the present experiment was designed to compare Ovsynch and Double-Ovsynch protocol for ovulation and pregnancy rate in crossbred cows.
MATERIALS AND METHODS
Animals and management: Lactating crossbred (Friesian x Jersey n=273) dairy cows from a commercial dairy farm located in District Kasur of Punjab province of Pakistan were used in the present experiment, conducted from November 2015 to February 2016. These experimental cows were accommodated in free stall barns, and fed with total mixed ration formulated at farm with 24 h free access to fresh water. These crossbred dairy cows were randomly selected to receive two different breeding groups or protocols; 1. Double- Ovsynch (DOS n=125)2. Ovsynch (OVS n=148). From each group, a subset of cows was randomly assigned, DOS n=20 and OVS n=21 for determination of ovulation. Furthermore, within each subset of cows, ten cows were randomly selected for blood sampling for determination of progesterone concentrations. These cows were at 60-180 days post-partum having body weight 480 ± 18 Kg with BCS 3.5 ± 0.35 (1 as thin and 5 obese as described by Ferguson et al.1994). These animals were ensured through rectal palpation that they had no abnormalities in their reproductive tracts.
Hormonal treatments, AI and blood collection: Crossbred cows (n= 273) were randomly divided into two treatments without determining the stage of estrous cycle (1) DOS; Double-Ovsynch (GnRH, 7 d PGF2α, 2 d GnRH, 7 d later GnRH, 7 d PGF2α, 2 d GnRH, 16~24 hour-TAI n=125) and (2) OVS; Ovsynch (GnRH 7 d PGF2α 2 d GnRH 16~24 hour-TAI n=148). Inseminations in all cows were performed with commercially available imported Holstein-Friesian bull frozen thawed semen (25 x 106 sperm / dose) by single technician. Ovulations were determined in a subset of cows (OVS n= 21 and DOS n= 20) seven days post TAI and pregnancy diagnosis was carried out at day 35 post TAI in all the cows enrolled in the both groups/protocols. The time line of the experiment is presented in (Fig. 1). The hormones used for synchronization programs were PGF2α (Dalmazin, 2 mL i.m.,Cloprostenol sodium 0.075 mg/mL; Fatro, Italy) and GnRH (Dalmarelin 4 mL i.m., Lecirelin acetate 25 µg/mL; Fatro, Italy). Seven days after TAI, ovulations were confirmed by visualization of CL, and pregnancy was diagnosed using trans-rectal linear transducer (Honda HS1500 Tokyo, Japan). Furthermore, for determination of P4 concentrations at day 7 after TAI, blood samples from ten randomly selected cows from each subset were withdrawn through tail vein puncture and placed in a vacutainer without anticoagulant (BD Vacutainer, by Preanalytical Solutions, Franklin Lakes, NJ).
Progesterone Estimation: The blood samples which were collected on day 7 after last GnRH injection of each protocol to determine the serum progesterone (P4) concentrations from each cow. Serum was separated after centrifugation (3000 rpm) from blood sample and stored at -20 ºC until assay. P4 assay was performed through commercially available competitive kit (DSI, P4 ELISA, Diagnostic Systems Ltd, Italy). The minimum detection level 0.156 ng/mL while coefficient of variation in intra-assay and was 3.5 and 6.2 % respectively.
Statistical Analysis: Ovulation and pregnancy per AI was analyzed using binary logistic regression test using Statistical Analytical System for Windows (SAS 9.2 Institute Inc, Cary, NC, USA). Student’s t-test was used to determine the difference between DOS and OVS protocol for progesterone levels using Statistical Software SPSS (version, 20, 2017).
RESULTS AND DISCUSSION
Effect of synchronization protocol on ovulation rate, serum concentrations of P4 and pregnancy/A.I in crossbred cows of this study are presented in Fig. 2. The outcomes of the present study revealed that ovulation rate was significantly high in DOS than OVS (90% vs. 47%; P<0.05, respectively). The pregnancy rate was also higher (62 % vs. 30%, P<0.05) in DOS than OVS. Serum progesterone concentrations after 7-days from last GnRH in each protocol was similar i.e., DOS; 8.68 ± 0.78 and OVS 8.19 ± 1.85 ng/mL (P>0.05). The suitability and successful induction of the DOS in various synchronization regimens has previously been reported in Holstein cows to improve the ovulation rate and fertility (Souza et al. 2008,Herlihy et al. 2012, Santos et al. 2017). Similarly, the findings of our study support the hypothesis that by using DOS protocol pregnancy rate in crossbred dairy cows can be enhanced under subtropical conditions. The results of this study revealed that the pregnancy rate in crossbred multiparous lactating cows was improved by 32% in DOS as compared to OVS. Similar findings have been reported in primiparous lactating Holstein cows where DOS protocol ensued 20% more pregnancy rate as compared to control groups (Souza et al. 2008) .In contrast to our findings, DOS protocol did not improve the pregnancy rate in multiparous lactating Friesian cows (Souza et al. 2008) . The recent meta-analysis conducted by (Borchardt et al. 2017), reported over all improved pregnancy rate in cows went under Double-Ovsynch protocol in general and lower specifically in multiparous cows. The variation in results of these experiments might be ascribed by the number of calvings, lactation yield, general management and dose of hormone for commencement of DOS protocol (Souza et al. 2008) .
In the present study, the application of DOS protocol demonstrated better ovulation rate than OVS (90 % vs. 47%). These outcomes are in agreement with earlier report in Holstein dairy cows in which the DOS enhanced the ovulation rate and fertility (Ayres et al. 2013). It is well documented that DOS increase fertility in cows by two mechanisms firstly by causing ovulation in acyclic cows, in response to the first part of DOS protocol so the response to subsequent hormonal injection becomes better and secondly by increasing the progesterone at the time when the second part of DOS is initiated (Souza et al. 2008).
The present study demonstrated that, DOS increased ovulation and pregnancy (P/A.I) in crossbred cows. These finds are in close agreement with previous studies which reported higher ovulation and pregnancy rate in DOS protocol followed by fixed time AI in lactating Holstein dairy cows as compare to the Ovsynch protocol (Souza et al., 2008; Ayres et al., 2013; Giardano et al., 2013). The increased pregnancy rate using DOS is already reported in anestrous Holstein dairy cows and primiparous cows compared to standard OVS (Souza et al. 2008, Öztürk et al. 2010,) . The DOS protocol yielded higher ovulation, synchronization rate and greater pregnancy P/A.I as compared to other pre-synch protocols even in heat stress lactating dairy cows (Dirandeh et al. 2015).. The enhanced fertility with Double-Ovsynch may be related to high progesterone during the follicular phase, that reduce the LH (Lutenizing Hormone) secretion and improve the quality of dominant follicle or oocyte (Mihm et al. 1994, Ferreira and Wiltbank 2008, Souza, Ayres et al.2013) .The results of the present experiment for post AI progesterone at day seven did not differ in the two protocols. For supporting the pregnancy, progesterone concentrations could be one of the factors for the successful pregnancy (Mann and Lamming 1999).
Fig. 1. Schematic diagram of synchronization protocols; Double-Ovsynch and Ovsynch in crossbred dairy cows
Conclusion: Taken together, it can be concluded that these data are new and solid that DOS resulted in higher ovulation and pregnancy rate than OVS in crossbred dairy cows. The most likely the driver for this higher fertility is the enhanced ovulation rate. It is implied that DOS as a pre-synchronization tool can be used safely in tropical and sub-tropical areas particularly when the herd fertility is compromised (This paper is based on a part from PhD research thesis)
Statement of Novelty: The Ovsynch is a normal routine reproductive management protocol with variable pregnancy rates at different farms and locations. In the present experiment, Ovsynch and Double-Ovsynch have been compared for ovulation and pregnancy rate followed by fixed timed AI in crossbred dairy cows.
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