PROSTAGLANDIN VERSUS PROGESTAGEN PROTOCOLS IN OESTRUS SYNCHRONIZATION IN THE YANKASA EWE

PROSTAGLANDIN VERSUS PROGESTAGEN PROTOCOLS IN OESTRUS SYNCHRONIZATION IN THE YANKASA EWE

 

Abstract

 

This study was carried out to compare the effects of prostaglandins (Lutalyse® and estroPLAN®) and progestagen (CIDR® and FGA-45®) in the synchronization of oestrus in Yankasa ewes. Cycling Yankasa ewes (n = 26), aged 1 to 4 years and weighing 14-28 kg with body condition scores of 2.5-3.5 were used in this study. They were randomly allocated into four groups: Group I ([YK-LT], n = 7) ewes were treated with Lutalyse®, Group II ([YK-ET], n = 7) with estroPLAN®, Group III ([YK-CD], n = 5) with CIDR® and Group IV ([YK-FG], n = 7) with Fluorogestone acetate-45®. The prostaglandin treatments were 2 intramuscular injections given 12 days apart while the progestagens were a-12-day intravaginal implants. Natural breeding was carried out using matured, sexually active proven rams for 5 days following the second prostaglandin injection in groups I and II and progestagen withdrawal in groups III and IV. Breeding was used to evaluate the effect of treatment in each group of ewes on parameters of oestrus (oestrus response rate, time-to-onset of oestrus, duration of oestrus, mean-mount per oestrus-detection-time and tightness of oestrus synchrony), conception rate (non-return to oetrus), pregnancy rate or progesterone profile. The results showed that oestrus response was 85.7 %, 100 %, 100%, 100 %, in the YK-LT, YK-ET, YK-CD and YK-FG groups, respectively. Time to onset of oestrus was 68.23 ± 17.28 h, 49.29 ± 4.48 h, 33.48 ± 8.58 h and 53.27 ± 12.33 h in the YK-LT, YK-ET, YK-CD and YK-FG, respectively. Duration of oestrus was 51.35 ± 13.9 h, 31.19 ± 7.9 h, 34.85 ± 8.3 h and 24.90 ± 6.3 h in the YK-LT, YK-ET, YK-CD and YK-FG groups, respectively. Mounts per oestrus period were 24.6 ± 5.9, 14.3 ± 4.3, 23.2 ± 6.8 and 14.7 ± 4.6 in the YK-LT, YK-ET, YK-CD and YK-FG groups, respectively. Conception rate equaled pregnancy rate and was 100 %, 100 %, 100 % and 86% in the YK-LT, YK-ET, YK-CD and YK-FG groups, respectively. The average serum progesterone (P4) concentrations 21 days post breeding were, 1.5 ± 0.54 ng/ml vs 2.7 ±0.35 ng/ml, 1.1 ± 0.28 ng/ml vs 3.1 ± 0.81 ng/ml, 1.1 ± 0.47 ng/ml vs 3.2 ± 0.44 ng/ml and 0.87 ± 0.38 ng/ml vs 2.3 ± 0.98 ng/ml in the YK-LT, YK-ET, YK-CD and YK-FG groups, respectively. Both protocols were efficient in oestrus synchronization. However, estroPLAN® and CIDR® offered the best results in synchronizing oestrus in Yankasa ewes and may be used by farmers to enhance productivity.

 

CHAPTER ONE

 

INTRODUCTION

 

1.1     Background

 

Oestrous synchronization is a process aimed at bringing animals to oestrus (heat) at a desired time by use of exogenous hormones to manipulate the life span of the corpus luteum (CL) and (or) to modulate follicular development (Siriwat, 2011). Oestrous synchronization increases the number of females pregnant early in the breeding season, which results in a shorter lambing season and a more uniform lamb crop at weaning (Siriwat, 2011). Oestrus synchronization is a valuable management tool that has been successfully employed to enhance reproductive efficiency in ruminants (Kusina et al., 2000). In small ruminants, it has been practiced for the last few decades. Many protocols have been developed to either shorten the luteal phase of the oestrus cycle with prostaglandins F_2α (Akusu and Egbunike, 1984; Ungerfeld and Rubianes, 2011) or prolong the luteal phase with exogenous progesterone (Gordon, 1975; Kruip and Brand, 1975; Oyedipe et al., 1989; Kusina et al., 2000; Omontese et al., 2010). Several protocols using a combination of progesterone, gonadotrophins and prostaglandins have also been applied in sheep (Oyedipe et al., 1989; Beck et al., 1996; Zarkawi, 2001; Husein and Kridi, 2002; Jafar et al., 2011).

 

Sheep is one of the principal domesticated small ruminant animals and they provide food and fibre products (Winrock International, 1983). They have lower feed requirements, compared to cattle due to their body size (Okunlola et al., 2010), which allows their integration into different farming systems (Hirpa and Abebe, 2008). Sheep play a significant role in the food chain and overall livelihoods of rural households, where they are largely the property of women and children (Lebbie, 2004). The world population of sheep has been estimated as 1,078,948,201 (Food and Agricultural Organization, 2010). In Nigeria, sheep population is currently estimated at 33.9 million, making up 3.1% of the world‟s total (Food and Agriculture Organization of the United Nations, 2011). In Africa, majority of the sheep population is owned by individuals or families in rural areas and the number per group is small (Okunlola et al., 2010). Traditionally, sheep serve as means of ready cash and as reserve against economic and agricultural production hardship (Hamito, 2008). Yankasa sheep is the most numerous breed of sheep in Nigeria, and having the widest distribution, it is found throughout the sub-humid and semi-arid zones (Federal Department of Livestock and Pest Control Services, 1991). It is estimated to constitute about 60% of the sheep population in Nigeria (Osinowo, 1992). Other breeds of sheep are Uda, Balami and West African Dwarf (WAD) sheep (Adebambo et al., 2000; Ozung et al., 2011). Fertility rates following oestrus synchronization have been attributed to factors such as heredity, breed, seasonality, age, environment, nutrition, diseases, semen quality, female reproductive status and hormonal treatment (Oyedipe et al., 1989; Beck et al., 1996; Lewis et al., 1996; Husein et al., 1998; Webb et al., 2004; Yavuzer, 2005).

 

1.2     Statement of the Research Problem

In Nigeria, human consumption of animal protein is below the recommended 28 g/person/day for a balance diet due to under-production (Ibe, 2004). A deliberate and conscious effort is needed to improve livestock production so as to increase protein supply. To control reproduction in ewes, it is important to adopt advanced pre-induced ovulation at a specific time and to achieve artificial insemination or natural service with satisfactory results (Cognie, 1988).

A wide variety of protocols have been used for synchronization of oestrus in sheep (Ungerfeld and Rubianes, 2011). This ranges from intravaginal progestagen sponges inserted for 12 to 14 days followed by equine chorionic gonadotrophin (eCG) at sponge removal to the use of prostaglandins (Gordon, 1975; Oyedipe et al., 1989; Zarkawi, 2001; Ungerfeld and Rubianes, 2011). Treatment of ewes with intravaginal sponges impregnated with progestagen (flurogestone acetate, FGA) or intravaginal device-containing progesterone, controlled internal drug release, (CIDR) for a period of 10 -16 days, with or without intramuscular injection of pregnant mare serum gonadotrophin (PMSG) at removal of intravaginal device, has been successfully used to improve reproductive performance (Kohno et al., 2005; Omontese et al., 2010; Jafar et al., 2011).

 

Treatment of ewes with intravaginal sponges impregnated with methyl acetoxy progesterone (MAP) for 14 days, intravaginal device containing progesterone (Controlled Internal Drug Release, CIDR) for a period of 12 days and intramuscular administration of pregnant mare‟s serum gonadotrophin (PMSG) at device removal as well as the use of prostaglandins in two intramuscular administrations 11 days apart have been successfully used to improve the reproductive performance (Hackett et al., 1981; Jafar et al., 2011). Comparative effect of different prostaglandins (estroPLAN^® and Lutalyse^®) and progestagens (CIDR^® and FGA-45^®) on oestrus response and reproductive performance in Yankasa sheep is yet to be evaluated in Nigeria.

 

 

1.3     Justification of the Study

 

Yankasa sheep constitute the largest sheep population in the northern part of Nigeria (Blench, 1999). Efforts to improve their reproductive efficiency through oestrus synchronization may improve the herd size as well as value for farmers. The application of assisted reproductive technologies (ARTs) such as oestrus synchronization will help improve reproductive performance in Yankasa sheep.

 

Significant increase in litter size has been reported following treatment with progestagens and prostaglandin F _2α or their analogues in other breeds of sheep (Ungerfeld and Rubianes, 2011; Jafar et al., 2011). However, information regarding comparative oestrus synchronization efficiency and fertility in Yankasa breed of sheep induced by different hormone treatments (progestagen or prostaglandin) is sketchy in Nigeria. Combination protocols of oestrus synchronization in most cases are expensive for farmers. More so, data on the efficiency of single oestrus synchronization treatment protocols in the Yankasa breed of sheep is scarce. This means that information regarding comparative oestrus synchronization efficiency using single hormone treatment (prostaglandins or progestagens) in Yankasa reed will be useful in the design of an intensive and cost- effective breeding programme. This study will also provide base-line data on reproductive performance in Yankasa ewes treated with different prostaglandins and progestagens.

 

1.4        Aim of the Study

 

The aim of this study was to compare the effectiveness of different prostaglandin (Lutalyse^® and estroPLAN^®) and progestagen (CIDR^® and FGA-45^®) treatment protocols in oestrus synchronization in Yankasa breed of sheep.

1.5     Objectives of the Study

 

To compare:

 

1. Effects of two different prostaglandin (Lutalyse^® and estroPLAN^®) and progestagen (CIDR^® and FGA-45^®) treatment protocols on oestrus parameters of Yankasa sheep.

 

2. Effects of two different prostaglandin (Lutalyse^® and estroPLAN^®) and progestagen (CIDR^® and FGA-45^®) treatment protocols on conception and pregnancy rates of Yankasa sheep.

 

3. Progesterone profile of Yankasa sheep following treatment with two different prostaglandin (Lutalyse^® and estroPLAN^®) and progestagen (CIDR^® and FGA-45^®).

 

 

PROSTAGLANDIN VERSUS PROGESTAGEN PROTOCOLS IN OESTRUS SYNCHRONIZATION IN THE YANKASA EWE

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