ABSTRACT
The study was designed to evaluate the efficacy of Controlled Internal Drug Release (CIDR-B), CIDR + Prostaglandin 2α and Prostaglandin F2α alone in synchronizing estrus, conception and pregnancy rates in Bunaji and Friesian x Bunaji cows. The study was conducted between July and October using forty seven cows (47) consisting of twenty four (24) Bunaji and twenty three (23) Friesian x Bunaji cows in a 2×3 factorial arrangement with eight (8) cows each except for treatment III which had seven (7) Friesian x Bunaji cows. Cows used for this study were rectally palpated for cyclicity, aged between 3-5 years and body condition score 2.5 and above. CIDR coated with 1.39g of progesterone was inserted through the vagina with the aid of an applicator, on day six (6) 2ml of PGF2α (Estrumate) was administered intramuscularly before CIDR removal on day seven (7). Behavioural signs of estrus were observed after insert removal, standing to be mounted was the primary sign of estrus used in this study and cows that came into estrus were inseminated by experienced inseminators 8-12 hours after. Retention rates were 100 % for all the treatments. Estrus response rates were 62, 56 and 26 for CIDR and CIDR + PGF2α respectively. Interval to onset of estrus was shorter for CIDR + PGF2α 3 hours and 1.75 hours than CIDR 5.0 hours and 5.0 hours in Bunaji and Friesian x Bunaji cows. Estrus duration was longer in Friesian x Bunaji; 12 hours CDIR, 13.5 hours than Bunaji 7.00 hours CIDR, 11.0 hours CIDR + PGF2α. Number of mounts were more in Friesian x Bunaji cows; 9.00 hours CIDR, 11.25 CIDR + PGF2α than in Bunaji 8.66 hours CIDR, 4.33 CIDR + PGF2α. More cows came into estrus between 6 am and 12 noon than 12 noon to 6 pm. Cows inseminated were rectally palpated for diagnosis of pregnancy. Conception rates were 33 % for Bunaji and 42 % Friesian x Bunaji treated with CIDR, 60 % for Bunaji and 50 % for
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Friesian x Bunaji treated with CIDR + PGF2α and 0 for Bunaji and 75 for Friesian x Bunaji treated with PGF2α. It is concluded from the study that, CIDR, CIDR + PGF2α are capable of synchronizing estrus in Bunaji and Friesian x Bunaji cows. Prostaglandin was effective only in Friesain x Bunaji cows. Estrus response, conception and pregnancy rates could be improved using a combination of CIDR + PGF2α.
TABLE OF CONTENTS
DECLARATION ……………………………………………………………………………………………………………… iii
CERTIFICATION ……………………………………………………………………………………………………………. iv
DEDICATION ………………………………………………………………………………………………………………….. v
ACKNOWLEDGEMENTS ……………………………………………………………………………………………….. vi
ABSTRACT ………………………………………………………………………………………………………………….. viii
TABLE OF CONTENTS …………………………………………………………………………………………………… x
ESTRUS SYNCHRONIZATION PROTOCOL ………………………………………………………………….. xv
CHAPTER ONE ……………………………………………………………………………………………………………….. 1
1.1 INTRODUCTION ………………………………………………………………………………………………….. 1
1.2 JUSTIFICATION …………………………………………………………………………………………………… 3
1.3 RESEARCH HYPOTHESIS ……………………………………………………………………………………. 5
1.4 OBJECTIVES OF THE STUDY ………………………………………………………………………………. 5
CHAPTER TWO ………………………………………………………………………………………………………………. 6
LITERATURE REVIEW …………………………………………………………………………………………………… 6
2.1 Physiology of the bovine estrous cycle ……………………………………………………………………………. 6
2.1.1 Estrous Cycle ……………………………………………………………………………………………………………. 6
2.1.1.1 Phases of the estrus cycle …………………………………………………………………………………………. 6
2.1.1.1.1 Estrus phase ………………………………………………………………………………………………………… 6
2.1.1.1.2. Metestrus phase ………………………………………………………………………………………………….. 8
2.1.1.1.3. Diestrus phase ……………………………………………………………………………………………………. 9
2.1.1.1.4. Proestrus phase ………………………………………………………………………………………………… 10
2.2. Estrus Detection ………………………………………………………………………………………………………… 10
2.2.1. Signs of estrus ………………………………………………………………………………………………………… 10
2.2.2. Methods of heat detection ………………………………………………………………………………………… 11
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2.2.2.1. Pedometry …………………………………………………………………………………………………………… 11
2.2.2.2. Measuring electrical Resistance …………………………………………………………………………….. 12
2.2.2.3. Tail painting ………………………………………………………………………………………………………… 12
2.2.2.4. Estrus alert devices ………………………………………………………………………………………………. 13
2.2.2.5. Remote sensing devices …………………………………………………………………………………………. 13
2.2.2.6. Teaser bulls …………………………………………………………………………………………………………. 13
2.3. Factors affecting heat detection …………………………………………………………………………………… 14
2.4. Follicular Development ……………………………………………………………………………………………… 15
2.5. Atresia ……………………………………………………………………………………………………………………… 18
2.6. Corpus Luteum Function and Luteolysis ………………………………………………………………………. 19
2.6.1. Luteolysis ………………………………………………………………………………………………………………. 21
2.7. Estrus Synchronization ………………………………………………………………………………………………. 23
2.7.1. Synchronization agent……………………………………………………………………………………………… 24
2.7.1.1. Prostaglandin F2α………………………………………………………………………………………………….. 24
2.7.1.2. Progestins ……………………………………………………………………………………………………………. 29
2.7.1.3. Gonadotropin Releasing Hormone (GnRH) …………………………………………………………….. 32
2.8. ESTRUS SYNCHRONIZATION PROTOCOLS ………………………………………………………….. 36
2.8.1. Progesterone Insert + PGF2α …………………………………………………………………………………….. 36
2.8.2. GnRH + Progesterone Insert (7 to 14 d) + PGF2α ………………………………………………………… 37
2.8.3. GnRH+CIDR (5 d) +PGF2α ……………………………………………………………………………………… 39
2.9. Artificial Insemination ……………………………………………………………………………………………….. 40
2.9.1. Origin ……………………………………………………………………………………………………………………. 41
2.9.2. Artificial insemination becomes a central point of research ………………………………………….. 41
2.9.3. Modern advances of artificial insemination in dairy cattle ……………………………………………. 43
2.9.4. Advantages of artificial insemination ………………………………………………………………………… 44
2.9.5. Disadvantages of artificial insemination …………………………………………………………………….. 45
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CHAPTER THREE …………………………………………………………………………………………………………. 46
3.0 MATERIALS AND METHODS………………………………………………………………………………….. 46
3.1. Study Location ………………………………………………………………………………………………………….. 46
3.2. Selection and Management of Experimental Animals …………………………………………………….. 46
3.3. Estrous synchronization ……………………………………………………………………………………………… 47
3.4. Estrus Detection ………………………………………………………………………………………………………… 49
3.5. Insemination and Pregnancy Diagnosis ………………………………………………………………………… 49
3.6. Data Collection …………………………………………………………………………………………………………. 50
3.7. Statistical Analysis …………………………………………………………………………………………………….. 51
CHAPTER FOUR …………………………………………………………………………………………………………… 56
4.0. RESULTS ………………………………………………………………………………………………………………… 56
4.1. RETENTION RATE …………………………………………………………………………………………………. 56
4.2. ESTRUS RESPONSE RATE ……………………………………………………………………………………… 56
4.3. INTERVAL TO ONSET OF ESTRUS ………………………………………………………………………… 56
4.4. ESTRUS DURATION ……………………………………………………………………………………………….. 56
4.5. NUMBER OF MOUNTS PER ESTRUS PERIOD ………………………………………………………… 57
4.6. SWOLLEN VULVA AND VAGINAL DISCHARGE RATE ………………………………………… 57
4.7. NUMBER OF COWS THAT EXHIBITED STANDING ESTRUS AT DIFFERENT TIMES OF THE DAY. …………………………………………………………………………………………………….. 59
4.8. CONCEPTION AND PREGNANCY RATES …………………………………………………………. 61
CHAPTER FIVE …………………………………………………………………………………………………………….. 63
5.0. DISCUSSION …………………………………………………………………………………………………………… 63
5.1. RETENTION RATE …………………………………………………………………………………………………. 63
5.2. ESTRUS RESPONSE RATE ……………………………………………………………………………………… 63
5.3. INTERVAL TO ONSET OF ESTRUS ………………………………………………………………………… 65
5.4. EFFECT OF PROTOCOL ON NUMBER OF MOUNTS ………………………………………………. 66
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5.5. SWOLLEN VULVA …………………………………………………………………………………………………. 67
5.6. NUMBER OF COWS THAT EXHIBITED STANDING ESTRUS AT DIFFERENT TIME OF THE DAY …………………………………………………………………………………………………………………. 67
5.7. CONCEPTION AND PREGNANCY RATES ……………………………………………………………… 68
CHAPTER SIX ……………………………………………………………………………………………………………….. 70
6.1. SUMMARY, CONCLUSION AND RECOMMENDATIONS ……………………………………….. 70
6.2. CONCLUSION …………………………………………………………………………………………………………… 70
6.3 RECOMMENDATIONS …………………………………………………………………………………………….. 71
REFERENCES ……………………………………………………………………………………………………………….. 72
CHAPTER ONE
1.1 INTRODUCTION
Synchronization of estrus (heat) involves manipulating the estrous cycle of female animals so they can be bred at approximately the same time. Estrus synchronization and artificial insemination (AI) are reproductive management tools that have been available to producers for over 30 years. These tools remain the most important and widely applicable reproductive biotechnologies available for cattle operations (Seidel, 1995). One measure of the reproductive efficiency of any cow-calf operation is the percent annual calf crop output. Reproductive inefficiency in cow-calf operation has been reported to reduce milk yield, number of replacement heifers and increase involuntary culling due to death, infertility and disease (Grohn and Rajala-Schultz, 2000). De Rensis (2000) reported an estimated loss of $300 million per year to the United States Dairy industry due to poor detection of estrus There is abundant literature on the influence of season on the reproduction of domestic animals (Rekwot et al., 1987). It is no longer in doubt that even in Nigeria the possibility of synchronizing estrus and ovulation in farm animals with the use of exogenous hormones exist. The broad objective of estrus synchronization programme is to be able to predict in advance the time a group of females that are ready to be bred and to obtain normal fertility at synchronized estrus.
During the last three decades, various estrus synchronization programmes have been adopted to control onset of estrus and artificial insemination in dairy cattle (Stevenson,
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1997; Voh, Jr. et al., 2004a; b). These are dependent entirely on manipulation of the corpus luteum by prolonging the luteal phase with progestagins or inducing premature luteolysis by prostaglandins. It has been reported that manipulation of ovarian follicular development by Gonadotropin Releasing Hormone (GnRH), human Chorionic Gonadotropin (hCG) or Pregnant Mare Serum Gonadotropin (PMSG) may be necessary adjunct for synchronization of ovulation and improving fertility (De Rensis, 2000). There are several protocols available for synchronizing estrus among female animals. Traditional protocols are designed to mimic or control the corpus luteum of the ovary. New protocols have been designed to control ovulation and/or the follicular waves that occur on the ovary during the 21-days estrous cycle. The synchronizing agents in use include progesterone compounds like Progesterone Release Intra-vaginal Device (PRID) (Sanofi, UK), Cystorelin, Ovacyst, Factrel, Fertagyl, Controlled Internal Drug Release (CIDR) (Carter Holt, New Zealand) and Synchromate B (Intervet, Holland) which extend the life span of the corpus luteum (CL) while luteolytic agents like Lutalyse (Upjohn, USA) and Estrumate (ICI, UK) which shorten the life span of the corpus luteum. The CIDR is a T-shaped rubber device that contains progesterone. Short and long-term treatments with the CIDR have been studied for oestrous synchronization. Longer treatment periods (14-21days) resulted in a high degree of estrus synchrony but reduced fertility at the synchronized estrus (Macmillan and Peterson, 1990). But it has been suggested that hormonal injections can be administered along with the CIDR treatment to increase efficiency (Medina-Britos et al., 2001).
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1.2 JUSTIFICATION
Reproductive performance has been declining in dairy cows with increasing number of days open and decreased conception rates over the last 25 years (Silvia, 1998). Several studies have estimated that ≤ 50% of the cows are detected in estrus (Barr, 1975; Stevenson and Britt, 1977; Heersche and Nebel, 1994). The use of milk progesterone assays indicate that between 5 and 25% of cows inseminated are not in estrus (Reimers et al., 1985; Nebel et al., 1987), with some herds having more than a 30% error rate. Average herd size continues to grow and making it even more challenging to accurately detect estrus (Xu and Burton, 1999). Increasing herd size and other factors have contributed to the difficulty with accurate estrus detection. While most producers have low estrus detection rates, leading to longer calving intervals and economic losses (Larson et al., 1992). Difficulties in estrus detection, silent estrus and unknown time of ovulation cause low reproductive performance in domestic animals (Zakari, 1981).
Estrus synchronization improves estrus detection rates (Ryan et al., 1999 and Xu and Burton, 1999). Synchronization of the estrus has the potential to shorten the calving season, increase calf uniformity, and enhance the possibilities for utilizing AI (Lamb, 2010), decrease culling rates, and improve net income to producers (Bellows et al., 1979). Regardless of the causes of the estrus detection problem, it has led to an increased interest in synchronization of estrus and ovulation. Estrus synchronization is a reproductive management tool that is particularly useful in artificial insemination (AI) and embryo transfer (ET) programs (Parish et al., 2011). It manipulates females‟ estrous cycles with one or more hormones to bring cattle into estrus (heat) within a short period of time
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(Parish et al., 2011). Estrus synchronization is important for the convenient timing of the breeding of cattle in artificial insemination and embryo transfer programs. Several methods have been used to synchronize estrus or induce heat in dairy cows; this include injection of prostaglandin (PGF2α) so as to shorten the estrous cycle and allows the cow to show heat during a restricted time period (Lamb, 2010).
Progesterone Releasing Intra-vaginal Devices (PRID; McPhee et al., 1983) and Controlled Internal Drug Release-Bovine (CIDR-B) devices (Macmillan et al., 1991) have been shown to successfully release progesterone at a fairly predictable rate. These two devices have been studied as methods for estrous synchronization as well as for studying follicular dynamics (Macmillan et al., 1991). Macmillan and Peterson (1990) found a conception rate of 58% in heifers treated with CIDR devices for 7 days and the Prostaglandin F2 alpha injected at device removal. The lining of the vagina absorbs the progesterone from the CIDR. Previous research has shown that increasing serum progesterone levels in dairy cows through administration of a controlled internal drug releasing device (CIDR) containing progesterone can result in increased conception and calving rates (Folman et al., 1990; Melendez et al., 2006). Buvanendran (1979), reported that several interrelated factors, such as genetic, physiologic, management and environmental factors are responsible for the less than average performance of dairy cows in Nigeria. Extreme environmental conditions such as temperature and humidity have been shown to decrease reproductive efficiency. Voh Jr. (1984) also reported that some of the factors responsible for low reproductive efficiency include irregular estrus cycles, poor signs of estrus and low fertility rates. Despite this the possibility of synchronizing estrus and ovulation in Nigerian cattle with exogenous hormone exist.
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1.3 RESEARCH HYPOTHESIS
HO: There will be no difference in estrus synchronization and conception rates when an injection of 2 ml of prostaglandin F2α (Estrumate (B)) administered on day 6 before removal of CIDR insert is compared with CIDR insert in place for 7days and 1dose of prostaglandin F2α (Estrumate (B)). HA: There will be difference in estrus synchronization and conception rates when an injection of 2 ml of prostaglandin F2α (Estrumate (B)) administered on day 6 before removal of CIDR insert is compared with CIDR insert in place for 7days and 1dose of prostaglandin F2α (Estrumate (B)).
1.4 OBJECTIVES OF THE STUDY
The objectives of the study were to determine:
1. the efficacy of CIDR alone, CIDR + PGF2α or PGF2α alone in synchronizing estrus in Bunaji and Friesian x Bunaji cows.
2. the effect of these protocols on the pregnancy and conception rates of Bunaji and Friesian x Bunaji cows.
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