CC BY
52018, Scienceline Publication
Worlds Veterinary Journal
World Vet J, 8(3): 55-64, September 25, 2018
Application of Different Hormonal Protocols for Improving Reproductive Performance of Barki Ewes
Gamal Ashour1, Moharram Fouad El-Bassiony2*, Sherif Mohamed Dessouki1 and Mohamed Awad El-Wakeel2
1 Department of Animal Production, Faculty of Agriculture, Cairo University, 12613, Giza, Egypt 2Animal and Poultry Physiology Department, Desert Research Center, 11753, Cairo, Egypt *Corresponding author's Email: [email protected]
ABSTRACT
This investigation was designed to assess reproductive improvement in Barki ewes using different hormonal protocols. Seventy-five non-pregnant and non-lactating Barki ewes were randomly assigned into three equal groups (25 ewes each), namely G1, G2 and G3. (G1) served as control, while (G2) was treated with an intravaginal progestagen impregnated sponge for 12 days then was removed. On the ninth day, all treated ewes received an intramuscular injection of prostaglandin F2a. (G3) was also synchronized as G2, in addition to on the 10th day ewes were received an intramuscular injection of 750 IU PMSG in descending doses for three days so that the last dose was injected at the 12th day concurrently with sponges' removal. Meanwhile, on the 14th day, all ewes in G3 were received an intramuscular injection of hCG hormone (500 IU/ewe). The results showed an increase in plasma progesterone level from the first day of pregnancy and rises up to the last day before parturition. Progesterone w found to be higher in G3 (that had higher twining rate) than in G2 than in G1. Insignificant increase in estrus response was observed in groups (G2, G3) compared to G1 (100, 100 and 92%, respectively). Conception rate was significantly higher in G3 (100%) than G2 (92%) and G1 (88%). While, abortion rate was higher in G1 and surpassing G2 and G3 (9.0, 0.0 and 0.0 %, respectively). Lambing rate was significantly higher in G3 as compared to G2 and G1 groups (100, 92 and 80 %, respectively). While, weaning rate was recorded to be insignificantly higher in G2 than in G1 and G3 (100.0, 95.45 and 94.29%, respectively). It could be concluded that, hormonal manipulation using intravaginal progestagen impregnated sponge and PMSG in the presence of hCG; would be a proper way for enhancing the reproductive efficiency of Barki ewes.
Key words: Barki ewes, Synchronization, Superovulation, Twining, Reproduction INTRODUCTION
Low reproductive performance has been observed in sheep flocks raised traditionally in arid regions. This poor performance may be attributed to several factors including fertility, selection, nutrition and disease (Webb et al., 2004; Yavuzer, 2005). Increasing Barki sheep productivity by increasing lambing frequency and fecundity is considered to be the most important factor in the development of Barki sheep production. In this regard, increasing the rate of fecundity in sheep offers the best opportunity to increase the efficiency of lamb meat production (Koyuncu and Alticekic, 2010). Natural lambing in Barki sheep occurs throughout the year in a scattered manner negatively affecting survival and growth rates of the lambs born during the unfavorable season of the year. Consequently, one of the most common ways to alleviate problems related to disorderly lambing is the using of exogenous source of hormones for artificially controlling the time of mating (Mekuriaw et al., 2016). In addition, the use of hormonal manipulation for estrus synchronization creates the opportunity for timed breeding and lambing. This in turn results in taking the advantages of seasonal variation of forage availability, photoperiod, labor resources and market demands. Estrus synchronization is a valuable management tool that has been employed successfully in enhancing reproductive efficiency, particularly in cows, ewes and does as early reported by Kusina et al. (2000). The success of a hormonal treatment for estrus synchronization depends on the productive status of ewes, season of the year, the type of hormonal protocol and the method of administration. Multiple ovulation programs are also possible with the use of estrus synchronization for improving herd productivity.
Estrus synchronization in small ruminants is achieved either by reducing the length of the luteal phase of the estrous cycle with prostaglandin F2a or by artificially extending it with exogenous progesterone or potent progestagens (Jainudeen et al., 2000 and Kusina et al., 2000). Synchronization of estrus has been practiced for the last few decades when many protocols varying in degrees of success which based on the use of intravaginal progestagen devises inserted for 7 to 14 days followed by gonadotropin injection at the time of devices' removal and introduction of teaser ram
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(Zarkawi, 2001). Also, hormonal treatments to control ovulation and reproduction are a perquisite for successful breeding and increasing the number of pregnant females (Motlomelo et al., 2002 and Husein et al., 2005). In small ruminants, several programs have been used for improving fertility by controlling the ovarian activity. Acceptable results of estrus responses have been achieved by using progestagen and equine Chorionic Gonadotropin (eCG) together at the time of progestagen withdrawal (Fonseca et al., 2005; Husein et al., 2005).
Application of assisted reproductive technologies is a prerequisite for improving reproductivity and productivity of livestock, especially in arid and semi-arid environments species which are usually characterized by low fertility. Most recently, Kaya et al. (2018) noted that hormonal protocols are one of the main items to improve, herds productivity including superovulation as proposed by Souza et al. (2014). In practice, generality of the superovulation protocols used for embryo production in ewes, both in vivo and in vitro, consists of the administration of intravaginal progestagen impregnated sponges; both for synchronization of estrus and ovulation or for avoidance of spontaneous ovulation (Cognie et al., 2003). The objectives of superovulation included inducing a high number of ovulations and subsequent high fertilization rate, while at the same time ensuring a normal physiological environment in the reproductive tract for embryo development. The application of superovulation technology to improve endogenous secretions of pregnant hormones increases offspring productivity and gross revenue in the small scale farm (Andriyanto and Manalu, 2011).
The present study was conducted to place on record the lambing rates of ewes following and to investigate the possibility of improving fertility and increasing twinning rate in Barki ewes under arid conditions of the North Western Coast of Egypt using different hormonal protocols for estrus synchronization and superovulation.
MATERIALS AND METHODS
Experimental region
The present study was carried out during the period from June 2015 to January 2016 at Animal Production Unit, Sustainable Development Center for Matrouh Resources, Matrouh Governorate, which belongs to the Desert Research Center (DRC), Ministry of Agriculture and Land Reclamation. The station is located at 240 Km West of Alexandria and 222 Km Egyptian western boarders.
Ethical approval
This experiment was performed according to all ethics and animal rights (Desert Research Center). As much as this work had considering all rules and regulations in conformity with the European union directive for the protection of experimental animals (2010/63/EU).
Experimental animals, feeding and management
Seventy-five, non-pregnant and non-lactating, Barki ewes averaged 48.10±0.72 kg Live Body Weight (LBW) and ranged between 2.5 and 3.5 years old were used in this study. All ewes were clinically examined for any reproductive disorders as well as general health status. Vaccination against the major prevailing epidemic diseases, internal and external parasites were controlled in proper time. Ewes were weighed before starting the experiment, and kept under an intensive production system and housed in semi-open yards throughout the experimental period. Lambs were left all the day time with their dams for suckling up to weaning age at three months of age. All groups were daily fed on a concentrate (0.75 kg) and berseem hay (0.5kg) per head during the experimental period to cover their nutrient requirements during different physiological status according to Kearl (1982). Lambs were daily fed only on their dams' milk from birth to weaning age at three months of age. The daily ration was offered in a certain mode of feeding starting with concentrate mixture at 08:30 h followed by chopped rice straw at 12:00 h and continuing to the next morning feeding. All animals drank fresh water three times a day (08:00, 14:00 and 20:00 h).
Experimental design
Animals were randomly divided into three equal groups (25 ewes per group (Figure 1). The first group (G1) was served as a control without any hormonal treatment and was left without synchronization or superovulation. While, the second group (G2) was treated using an intravaginal progestagen impregnated sponge (20 mg cronolone, Chronogest® CR, product of intervet international B. V. and manufactured in the European Union, (EU) was inserted. Sponges remained in situ for 12 days and were removed on the 12th day. On the ninth day, all ewes were received an intramuscular injection of prostaglandin F2a (1 ml Synchromate each 1 ml solution containing 0.250 mg Cloprostenol, Bremer Pharma GMBH, Germany). The third group (G3) was also synchronized using an intravaginal progestagen impregnated sponge for 12 days and received an intramuscular injection of prostaglandin F2a, on the ninth day, while on the 10th day ewes of the third group (G3) were received an intramuscular injection of 750 IU PMSG (Laboratorios Hipra, S.A. Avda. Ia Selva, 135, 17170 Amer (Girona) Spain). PMSG injections were applied in gradual decreasing doses for
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three days that each ewe received 275 IU at the 10th day, the second dose (250 IU) was injected at the 11th day, while the last dose (225 IU) was injected at the 12th day at the time of sponges' removal. Meanwhile, on the 14th day, all ewes in G3 group received an intramuscular injection of 500 IU/ewe of hCG hormone (Epifasi lyophilized ampoule contains 5000 I.U. of Human Chorionic Gonadotrophin, hCG) and 10 mg of lactose, manufactured by Egyptian int. pharmaceutical industries Co. (EIPICO, Egypt). During the synchronization period, all synchronized animals were subjected to a twice daily check (morning and evening) to ensure that sponges remained in their position during the treatment period.
Estrus detection and mating
Figure 1. Experimental design and timeline for the treatment administration for the control (G1), synchronization (G2) and synchronization + superovulation (G3) groups.
Blood sampling and progesterone assay
Blood samples (5 ml) were collected from the jugular vein into EDTA (ethylenediamine tetra-acetic acid) containing tubes. Blood samples were collected immediately before sponge insertion on day 0 from ewes. The rest of the samples were withdrawn on days 1, 3, 5, 7, 9, 10, 12, 13, 15, 17, 19, 30, 60, 90, 120, 150, 180 from all groups. Blood plasma was pipetted into 1.5 mL Eppendorf tubes using sterilized plastic disposable Pasteur pipettes and then stored at -20 °C until assayed for (P4) concentration. Progesterone hormone was quantified by ELISA method using BIOS kit provided by Chemux Bioscience Corporation, 385 Oyster Point Blvd Suite 5-6., South San Francisco, CA 94080, USA. The standard curve ranged between 0-50 ng/ml. The sensitivity of the curve was 0.2 ng/ml.
Estrus detection and mating
Nine fertile Barki rams were introduced to the ewes of all experimental groups, three rams for each group for estrus detection and mating; started 24 hours after removing the sponges (G2 and G3) and left to one week. While the control group (G1), rams left with ewes from the zero day throughout two estrus cycles (35 days total). Rams were allowed to
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interchange among different ewe groups to avoid sire/group confounding effect. The fertile rams' chest was colored in a different color for each group.
Rams were introduced to ewes for seven days and left with them for estrus detection and natural mating. Estrus was checked continuously by observation of the color marks on the ewe's rumps. Ewes were considered in estrus and mating had occurred when the paint mark was heavy and evenly distributed or copulation was observed.
Reproductive parameters
The following traits were estimated for each of the treated groups:
• Estrus response = number of ewes showing signs of estrus / total ewes treated in each group ><100.
• Conception rate = number of ewes conceived / number of ewes showing estrus and mated in each group ><100.
• Lambing rate = number of ewes lambed / number of ewes mated in each group ><100.
• Weaning rate = number of lambs weaned / number of lambs born in each group ><100.
• Abortion rate = number of ewes aborted / number of ewes conceived in each group *100.
• Litter size at birth = number of lambs born / number of ewe lambed.
• Litter size at weaning = number of lambs weaned / number of ewe lambed.
• Average litter weight at birth = the kilograms lambs born / number of ewe lambed.
• Fecundity rate = number of lambs born / number of ewe mated.
• Weaning weight = the kilograms lambs weaned / number of lambs weaned.
• Mortality rate up to weaning (%) =live lambs born - lambs weaned / live lambs born x100.
Statistical analysis
A General Linear Model procedure (SAS, 2004) was used for the statistical analyses of progesterone concentration, milk yield and composition during the experimental period using the following model:
Yijk = ^ + Pi + Tj + (P*T) ij + eijk
Where,
Yijk = Any observation of kth animal within jth treatment within ith period
^ = Overall mean
Pi = Effect of ith period
Tj = Effect of treatment (j = 1-3, 1= Tr1, 2= Tr2, 3= Tr3)
(P*T)ij = The interaction between period and treatment eijk = Experimental error
Significant differences among means were detected using Duncan's multiple range test (Duncan, 1955). While, reproductive traits (estrus response, conception, lambing, weaning, fecundity, abortion, single, twining, triple, mortality rates) and litter size at birth, litter size at weaning, weaning weight, sex ratio were analyzed using Chi-square test.
RESULTS AND DISCUSSION
Estrus response, and conception and abortion rates
The data presented in table (1) revealed that estrus response was non-significantly high in G2 (FGA+PGF2a) and G3 (FGA+PGF2a+PMSG and hCG) than the G1 (control group). The recorded data were (100, 100 and 92%, respectively). The data also indicated that conception rate was significantly higher (P<0.05) in G3 than in G2 and G1 (100, 92 and 88%). On the other hand, abortion rate was higher in control group (G1) surpassing G2 and G3, as both groups G2 and G3 showed no abortion (9.0, 0.0 and 0.0%, respectively) (Table 1).
Table 1. Estrus response and conception and abortion rates % of Barki ewes as affected by different hormonal protocols (LSM±SE)
Traits Treatment (T) ± SEM Significance
G1 G2 G3
Estrus response 92.00 (23/25) 100.0 (25/25) 100.0 (25/25) 97.33 (73/75) 5.30 NS
Conception rate 88.00 (22/25) 92.00 (23/25) 100.00 (25/25) 93.33 (70/75) 4.87 Ä
Abortion rate 09.00 (2/22) 00.00 00.00
G1 = control group; G2 = FGA and PGF2a; G3 = FGA, PGF2a, PMSG and hCG; NS = non-significant
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The results of this study confirm that using the intravaginal progestagen impregnated sponge is an effective tool for the synchronization of the estrus. These results were previously confirmed in goats at the beginning of the breeding season in semi-desert conditions (Riaz et al., 2012). In our study, progesterone treatment lasted for 12 days showed high efficiency. Hosseinipanah et al. (2014) concluded that the occurrence of estrus using CIDR in non- reproductive season for 10, 12 and 14 days was associated with the onset of good estrus and use of GnRH had positive effect on fertility in treatment groups, with the highest significant value for the 12 days P4 treatment. In the same year, Zoharaa et al. (2014) recorded higher pregnancy rates as observed in the 30 mg FGA treatment (100%) compared with 100 ^g Cloprostenol (88.2 %), 175 ^g Cloprostenol (75%) and 45 mg FGA (93.8 %) treatments. It was concluded that though FGA sponge protocol presented superior results.
In comparison with our results, Abdul Muin et al. (2013) suggested that CIDR treatment for 14 days with 400 IU PMSG and 0.05 mg cloprostenol prior to CIDR removal gave better result in estrus synchronisation than in CIDR treatment for 9 days with 0.05 mg cloprostenol given 24 hours before CIDR removal. In the present study both treatments were high to estrous response with no significant except to the control group. But the results of this study agree with recent report of Waheeb et al. (2017) who concluded that intravaginal progesterone sponge for 7 days+500IU eCG at sponge removal is convenient for estrus synchronization of ewes raised in field conditions during breeding season specially that the reproductive and fertility parameters recorded in his study were acceptable and within values reported previously in farm conditions. Also, Dendena (2017) stated a fertility rate of 85.1% after the administration of 500 IU of eCG, which was considered lower than PMSG treatment in this study, this may be referred to using higher dose (750 IU) in our treated group. Thus, our results were comparable to what has been most recently reported by Fornazari et al. (2018) as these stated that short-term progestagens (FGA e MAP) + eCG were 100.0% efficient in Assaf breed in cycle control worth to mention that in the same study the administration of 750 IU of eCG determined a fertility rate of 76.5%, which was controversially to our results. From our point of view, less prolific and less seasonal breeds tend to be more responsive to eCG administration, specially that different follicular populations present on the ovaries before progestagen treatments + eCG may also condition fertility rate (Omontese et al., 2016). In general, the present results meet these last investigators' observations that exogenous gonadotropin administration advanced ovulation and higher estrus synchronization precision (Letelier et al., 2011; Valentim et al., 2016), as they support ovarian mechanisms affecting follicular growth and maturation and promoting the proper luteinization of the CL (Valentim et al., 2016). In most studies, it is mentioned that in adult animals the expected estrus rate is greater than 90%, while nulliparous goats can reach up to 97.2% and lactating animals up to 85.7% (Abecia et al., 2011; Navanukraw et al., 2014; Alvarado-Espino et al., 2016).
Lambing rate, abortion rate, weaning rate, fecundity rate, litter size at birth, litter size at weaning and mortality rates (%)
Lambing rate is expressed as the percentage of ewes lambed out of ewes mated. As shown in table 2 lambing rate was significantly higher (P<0.05) in G3 as compared to G2 or G1 (100, 92 and 80%, respectively). While, weaning rate was recorded to be higher in G2 than in G1 and G3 and showed non-significantly rates of 100.0, 95.45 and 94.29%, respectively.
Table 2. Lambing rate, weaning rate, fecundity rate, litter size at birth, weaning rate, litter size at weaning and weaning weight of Barki ewes as affected by different hormonal treatment (LSM±SE)
Traits Treatment (T) Overall ± SEM Sig.
G1 G2 G3 mean
Lambing rate (%) 80.00 (20/25) 92.00 (23/25) 100.00 (25/25) 90.67 (68/75) 4.63 **
Weaning rate (%) 95.45 (21/22) 100.0 (26/26) 94.29 (33/35) 96.39 5.95 NS
Fecundity rate (%) 0.88b (22/25) 1.04b (26/25) 1.40a (35/25) 1.10 0.10 **
Mortality rate (%) 4.55 (1/22) 0.00 (0/26) 5.71 (2/35) 3.61 -- NS
Litter size at birth/ewe 1.10b (22/20) 1.13b (26/23) 1.40a (35/25) 1.22 0.05 *
Litter size at weaning/ewe 1.05 (21/20) 1.13 (26/23) 1.32 (33/25) 1.17 0.05 NS
Day 90 (Weaning weight)(kg) 16.71 17.53 17.45 17.28 -- NS
G1 = control group; G2 = FGA and PGF2a; G3 = FGA, PGF2a, PMSG and hCG; Sig. = significance; NS = non-significant Means within each row with different superscripts are significantly different at 5% level.
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As reported in our study, fecundity rate was significant higher in G3 and G2 than in G1 (1.40, 1.04 and 0.88), respectively (Table 2). Moreover, litter size at birth as expressed as number of born lambs per ewe lambed is considered to be an important parameter of fertility. Data illustrated in table 2 indicated that litter size at birth was significantly the highest in G3 followed by G2 as compared to G1 (1.40, 1.13 and 1.10, respectively). Litter size at weaning was significantly higher in G3 then G2 than in G1 (1.32, 1.13 and 1.05 respectively). The data also revealed that weaning weight showed insignificant increase in G2 as compared to G3 and G1 (17.53, 17.45 and 16.71, respectively). Nonsignificant higher values were recorded for mortality rate in G3 and G1 than in G2 (5.71, 4.55 and 0.00%, respectively).
In the tropics, biological and economic efficiency of animal production are predominantly determined by reproductive performance. Fertility is categorized as important parameters for determination the productivity of sheep; fertility may be estimated by several indicators as litter size per lambing for example which is more important than weight gain of lambs. Profit gain from increasing lamb survival is the major concern of sheep producers (Elliott et al., 2011). According to Elliott et al. (2011), sheep producers believed that using teasers for estrus synchronization, minimizing handling and interrupting ewes during the peri-partum period, and limiting duration of the breeding period would be beneficial to lamb survival. Contrarily to our results, it has been confirmed that high dose of eCG increases the ovulation rate but also reduces the embryonic survival rate (Diskin and Morris, 2008).
Formerly Gongnet (1996) reported malnutrition as the main cause of lamb mortality before weaning in lambs, for that reason, in recent study by Allou et al. (2013) advised with proper diet to enhance the adequate health that improve the survivability and lambs growth during the first three months of age. While, Gbangboche et al. (2005) referred the lamb survival rate before weaning to the age of the sheep at the first lambing influences, this was confirmed by Allou et al. (2013), who had stated that lambs survival is positively and beneficially correlated with this influence . Early reports indicated that the number of lambs surviving until weaning has been found to be influenced by ewes' body condition score at mating (Carson et al., 2001) rather than other surrounding factors.
Lambs with intermediate birth weights have a lower mortality risk than small and very large lambs (Piwczynski et al., 2012). However, the association between lamb birth weight and mortality was not detected in a study by Brien et al. (2009). In this regard, due to negative effects of large litters on lamb survival, close supervision should be provided to non-singleton lambs (Chniter et al., 2011). Litter size is influenced by several factors, and is low in ewes younger than 2 years of age and ewes having low weight at mating (Atashi et al., 2013). Weight gain in lambs is described by two subsequent phases, the first lasts from birth up to 90 days with a moderate weight change, this phase is followed by very fast changes in weight form 90 days until 200 days (7 months) of age (Allou et al., 2013).
Progesterone concentration
The results in Figure 2 to elucidate that plasma progesterone levels (ng/ml) as affected by FGA and PGF2a (G2) and FGA, PGF2a, PMSG and hCG (G3) as compared to the control group (G1). It could be observed that P4 levels attended to increase from the first day of pregnancy and rises to the end of the day before parturition. Also, progesterone was higher in G3 which contains the highest values of litter size at birth of newborn lambs as a result of increasing twinning rates in response to hormonal treatment for the superovulation. Mean concentration of P4 level was found to be 8.47 ng/ml in G3 followed by G2 (8.05 ng/ml) while the lowest value was observed in G1 (7.40 ng/ml).
Early pregnancy is a critical period for maternal recognition, and the lack of nutrients that stimulate an increase in circulating progesterone can increase early embryonic losses (Vinoles et al., 2012). According to Mann et al. (2006), most embryonic losses occur during the first few days after fertilization and during the implantation process, inadequate luteal function being one of the main causes. The maintenance of pregnancy in ruminants depends on the continued secretion of progesterone by the corpus luteum, which inhibits luteolysis. Progesterone deficiency due to primary luteal insufficiency has been reported as a cause of embryonic death (Mann and Lamming, 2001; Diskin and Morris, 2008). Increase concentrations of progesterone (P4) during meta-oestrus and early di-oestrus improves embryonic growth and the production of interferon-T (IFN-t) (Spencer, 2013 and 2016; Arosh et al., 2016), which in turn improves the relationship between embryo and uterus and increases embryonic survival rates (Mann et al., 2006).
The higher values of progesterone levels, found in G3 followed by G2 than that in the control group, may be due to the number of corpora lutea present as it is the source of progesterone in sheep. El-Tarabany (2012) found that progesterone concentration decreased significantly in ewes conceived single than in ewes conceived twin's fetuses by 34.3%. Also, Khan and Ludri (2002) found that in twin bearing goats' plasma progesterone level was significantly higher than in single bearing goats during all days of experiment. Manalu et al. (1998) reported that ewes with a high litter size had heavier placental tissue. Moreover, ewes with a high litter size had high ovulation rates that resulted in high number of corpora lutea as sources of progesterone during the embryonic phase of pregnancy and, probably, throughout the pregnancy period
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Time of sampling (days)
Figure 2. Plasma progesterone levels (ng/ml) as affected by FGA and PGF2a (G2) and FGA, PGF2a, PMSG and hCG (G3) compared to the control group (G1). G1 = control group; G2 = FGA and PGF2a; G3 = FGA, PGF2a, PMSG and hCG
Type of lambing and sex ratio
The data presented in table 3 demonstrate that single rate was significantly higher in the control non treated group (G1) as compared to other treated groups, being 90.00, 86.96 and 64.00%, respectively. Results of present study indicated that twining rate significantly increased in the hormonal manipulated group (G3) than (G2) and (G1) being 32.00, 13.04 and 10.00%, respectively, (Table 3). The influence of the superovulation treatment was observed for G3, as triple rate increased significantly in G3 as compared to other groups, with values of 4.0, 0.0 and 0.0%, respectively. Sex ratio (female %) exhibited significantly the highest values for G3 (60.00%) followed by G2 (59.09%) and finally G1 (46.15%). Conversely, sex ratio (male %) was significantly higher in G2 than in G1 and G3, recording 53.85, 40.91 and 40.00%, respectively.
A like to the Barki breed in our study herein, Awassi breed is a monotoccus with an ovulation rate of 1 and very low incidence of twinning (Jaber et al., 2004). For that reason, the twins and triplets born lambs weighed less at birth as compared with singles in control groups, this might be due to the competition between fetuses for nutrient supplied by the placenta from maternal circulation for growth due to the low capacity of uteri to provide for twins (Baneh and Hafezian, 2009). In Barki, twining in general and especially triple births is not common. Moreover, Clement et al. (1997) in his study assumed that the longer of lambing interval is accompanied with the increase in the range of sizes with the rank of lambing. Herein this study triples birth in group 3 (G3) is probably accompanied with the effect of PMSG injection. Sheep male lambs' are known to be born heavier than females, (Gbangboche et al., 2005), who also reported that this trend in weight significant different may last up to 12 months or more, this observation is reported under same rearing conditions for birth weight for males and females, but these variations tends to disappear at 120 days of age (Poivey et al., 1982; Fall et al., 1983). Binns et al. (2002) and Brien et al. (2009) found higher mortality in male than female lambs. On the other hand, another study reported a higher survival risk in male lambs (Atashi et al., 2013), while mortality risks for gender were not statistically different in a study in Quebec (Arsenault et al., 2003).
Table 3. Types of lambing and sex ratio (%) of Barki ewes as affected by different hormonal protocols (LSM±SE)
Traits Treatment (T) Overall ± SEM Significance
G1 G2 G3 mean
Single rate 90.00 (18/20) 86.96 (20/23) 64.00 (16/25) -- -- --
Twining rate l0.00b (2/20) 13.04b (3/23) 32.00 a (8/25) 18.34 2.74 **
Triple rate 0b 0b 4.00a (1/25) -- -- --
Sex ratio (female) 59.09 (13/22) 46.15 (12/26) 60.00 (21/35) 55.42 (46/83) 1.62 *
Sex ratio (male) 40.91 (9/22) 53.85 (14/26) 40.00 (14/35) 44.58 (37/83) 1.62 *
G1 = control group; G2 = FGA and PGF2a; G3 = FGA, PGF2a, PMSG and hCG. Means within each row with different superscripts are significantly different at 5% level.
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CONCLUSION
It could be concluded that, hormonal manipulation using intravaginal progestagen impregnated sponge and PMSG in the presence of hCG; for estrous synchronization and superovulation; would be a proper way for enhancing the reproductive efficiency of Barki ewes.
Acknowledgments
The authors are thankful to Dr. Khalid El-Bahrawy for his support and assisting in lab work and guide through writing the manuscript. Deepest thanks are due to Dr. Hamdy Gawish for facilitating the research work at the Sustainable Development Center for Matrouh Resources. We also would like to appreciate all participants who contributed during sample collection.
Competing interests
The authors declare that they have no conflict of interest with respect to the research, authorship, and/or publications of this article. The authors declare that they have no competing interests.
Author's contribution
Dr. Gamal Ashour designed the experiment, article writing and revision, Dr. Moharram Fouad El-Bassiony designed the experiment, laboratory analyses, statistical analysis, tabulation of experimental data, manuscript writing, commenting and approval, Dr. Sherif Mohamed Dessouki helped in statistical analysis, tabulation of experimental data and article writing; while, Mr. Mohamed Awad El-Wakeel helped in field study, collected data, laboratory analyses, manuscript writing. All authors have read and approved the final manuscript.
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