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Objective: Embryo vitrification facilitates multiple ovulation and embryo transfer (MOET) application in the sheep industry through the storage and transfer of genetically superior embryos. This study assessed the survival rate of vitrified embryos following direct transfer under field conditions. Materials and Methods: Thirty-five donors and 46 recipient ewes were synchronized for estrus using two injections of Cloprostenol. Superovulation was induced with 25 mg porcine follicle- stimulating hormone per donor twice daily for 4 days. Recipients were treated with 250 IU of pregnant mare serum gonadotrophin during the second injection of cloprostenol to ensure ovulation. Estrus donors were mated with rams. Embryos were collected on day 6 post-mating using a modified inguinal laparotomy and graded. Grade 1 embryos were vitrified in a medium containing tissue culture medium 199, 10% ethylene glycol, 10% dimethyl sulfoxide, and 0.5M sucrose and stored in liquid nitrogen. Following thawing, embryos were directly transferred to recipients through an open-pulled straw following an inguinal laparotomy. Sixteen recipients were treated with 20 μg Gonadorelin immediately after embryo transfer. Results: Onset and duration of estrus in donor and recipient ewes were 30.2 ± 0.8, 27.9 ± 0.6, and 33.7 ± 0.4, 27.50 ± 0.42 h, respectively. Corpora lutea number and recovered embryos/donor were 8.47 ± 0.68 and 6.93 ± 0.57, respectively. 85.7% of donors responded to superovulation treatment, and the embryo recovery rate was 82.5%. Grade 1 embryos per donor (5.5 ± 0.8) were significantly higher (p < 0.05) than all other grades. Pregnancy rates in recipients treated with Gonadotrophin-releasing hormone (GnRH) and without GnRH treatment were 62.5% and 56.6%, respectively. The respective lambing rates were 80% and 76.5%. Conclusion: These findings indicate the potential on-farm application of direct transfer of vitrified embryos in facilitating a MOET program for genetic improvement of sheep in Bangladesh.

The purpose of this study is to compare five protocols of estrous synchronization for Hu ewes to obtain the most effective and economical protocol, to apply the advantageous scheme in large-scale sheep farming. Healthy multiparous Hu ewes ( n = 150) were randomly divided into five groups, and all ewes were administered fluorogestone acetate (FGA, 45 mg) vaginal sponge. The sponges of the first three groups (Groups I, II, and III) were removed on the 11th day, and 0.1 mg of PGF 2α was injected intramuscularly on the ninth day. Group I received 6 μg of gonadotropin-releasing hormone (GnRH) by intramuscular injection at 36th h after withdrawal of the sponge. Group II was injected 330 IU of pregnant mare serum gonadotropin (PMSG) on the ninth day. The combination of 6 μg of GnRH and 330 IU of PMSG was treated in Group III at the same time as Group I and Group II. The sponges of the latter two groups (Groups IV and V) were removed on the 13th day, and 330 IU of PMSG was injected intramuscularly simultaneously. PGF 2α (0.1 mg) was administered on the 12th day in Group IV. All ewes were detected for estrus at 24, 36, 48, 60, and 72 h after the sponge removal. The loss of sponge and vaginitis was recorded when the sponge was withdrawn. Cervical artificial insemination (AI) was performed with fresh semen of Dorper rams diluted with skimmed milk. After 30 days of insemination, the conception was detected with a veterinary B-ultrasound scanner. The lambing status of all ewes and the cost of drugs for estrous synchronization in each group were recorded. The results showed the following: (1) on the whole, the average percentage of estrous ewes in the period of 24–36 h and 36–48 h after removal was significantly higher than other three periods and that of the period of 60–72 h was significantly lower than the first three periods after removal; (2) there was no significant difference in percentages of estrous ewes in any of the five time periods, sponge loss rate, vaginitis rate, total percentage of estrous ewes, conception rate, single lambing rate, twinning rate, and multiple lambing rate of ewes among five protocols; (3) total percentage of estrous ewes and conception rate were more than or equal to 80% in the Groups II and III, and the twinning lamb rate of the Group II protocol was 70%; (4) there was no difference in lambing rate of ewes among Groups II, III, IV, and V; (5) the Group III had the highest drug cost of 22.5 CNY. In conclusion, considering the lambing rate, twinning lamb rate, and drug cost for estrous synchronization, Group II was the most advisable for application and promotion in large-scale sheep farms among these five protocols of estrus synchronization.

The aim of the current study was to investigate the effects of injecting estrus-synchronized ewes with vitamin E and selenium (Se) on their reproductive performance. Awassi ewes (n = 74) were randomly assigned into one of two groups. Group one (control, n = 36) did not receive vitamin E/Se injections, and group two (vitamin E/Se, n = 38) received 13.6-mg/kg BW of vitamin E plus 0.045-mg/kg BW of Se. Concurrent with estrus-synchronization program, vitamin E/Se injections were given at the time of insertion, withdrawal, and 19 days after withdrawal of intravaginal sponges. At all injection times, serum samples were collected (20 ewes per group) to measure Se contents. Pregnancy rates were evaluated by progesterone assay and by ultrasonography, respectively, at days 19 and 40 after sponge removal. Lambing rate, singles and twins%, sex ratio (M:F), and birth weight were recorded at lambing. Vitamin E/Se injections did not affect (P > 0.25) BW at lambing or BW change of ewes from breeding to lambing. Vitamin E/Se injections tended (P = 0.08) to decrease total pregnancy losses from 44.8 to 24.3%, subsequently, injections positively improved (P < 0.05) pregnancy rates determined by progesterone assay (from 80.6 to 97.4%) and ultrasonography (from 63.9 to 86.8%). Although overall fertility was not affected, vitamin E/Se injections markedly increased the percentage of ewes that lambed after only one service from 64.0 to 93.3%. Singles and twins%, lamb sex ratio, and birth weight of lambs were not affected (P > 0.20) by vitamin E/Se injections. Under conditions of our study, multiple injections of vitamin E/Se improved the reproductive performance of estrus-synchronized ewes.

The aim was to explore the impact of periconceptional folic acid or flaxseed oil (FXO) supplementation on fertility, progesterone profile, and blood chemistry in pregnant ewes during the breeding season. In total, 54 Ossimi ewes were divided into three groups (18 animals each). The control treatment (CON) fed a basal diet only, while the others fed the basal diet and supplemented every other day with a single bolus of folic acid (FO 500 μg/head) or flaxseed oil (FX 50 ml/head). During the early stage of pregnancy, the FO and FX groups showed significantly higher serum antioxidant activity (glutathione and superoxide dismutase) as compared with the control CON group (P = 0.012 and 0.007, respectively). Although no significant variations were detected in the serum nitric oxide levels during the early stage and mid-stage of pregnancy, the FO and FX groups showed significantly lower serum nitric oxide concentration in the late stage of pregnancy (P = 0.001). The FO and FX groups showed significantly higher serum progesterone concentrations during the early stage (10.9 and 11.4 ng/ml, respectively) and mid-stage (22.2 and 23.4 ng/ml, respectively) of pregnancy as compared with the CON group (7.72 and 13.9 ng/ml, respectively). The FX group exhibited a significantly higher lambing rate (P = 0.034), as well as the proportion of female lambs (P = 0.029) as compared with the CON group. In conclusion, supplementing Ossimi ewes with folic acid or FXO significantly improved the progesterone profile during pregnancy. Moreover, the FXO supplementation significantly increased the lambing rate and the female lamb rate as compared with the control group.

Objective: Lambing in ewes is a complex and crucial aspect of sheep production that directly influences economic viability and production efficiency. In the present study, we analyzed the genomes of single lamb (SLE) and twin lamb (TLE) Hotan sheep to elucidate the genetic mechanisms underlying lamb production in Hotan sheep.Methods: In this study, we used genome-wide resequencing to analyze the genomes of Hotan sheep exhibiting SLE and TLE traits. To identify the population genetic structure and linkage disequilibrium associated with SLE and TLE traits, we employed two complementary genome selection signals: the interpopulation genetic differentiation index (FST) and nucleotide diversity. Subsequently, we performed gene annotation and enrichment analyses of the selected regions of the obtained genome.Results: Our analysis generated 801 Gb of sequence data, from which 31,864,651 highquality single nucleotide polymorphic loci were identified. We identified 290 selected regions and 332 genes across the Hotan sheep genome by using two widely adopted selective scanning detection methods (FST statistics and Piratio). Functional annotation and enrichment analysis of these genes identified 13 genes associated with the lambing rate, which were enriched in pathways such as the transforming growth factor-β signaling pathway (BMPR2, ID2, SMAD7, THBS1, and RBX1), renal cell carcinoma (PAK1, ELOC), inositol phosphate metabolism (PLC), non-homologous terminal junction (RAD5), ABC transporters (ABCC4), and the NET pathway (H2B, H4, and H2A).Conclusion: This study employed selective elimination analysis to identify candidate genes involved in the regulation of lambing trait in Hotan sheep. By investigating the molecular mechanisms underlying lambing rate in Hotan sheep, we developed molecular markers for twin lambing to enhance reproductive performance and promote the conservation and development of outstanding genetic resources in local Xinjiang sheep.

This study was conducted to evaluate the effect of feeding different sources of fat during flushing period on the reproductive performance, lambing percent, and twin numbers of Afshari ewes. A total of 84 ewes (mean weight 48 ± 3 kg; age: 3–4 years) were divided into seven groups of 12 animals and received flushing-specific rations for 5 weeks. The control group just received a basic ration (non-flushing). Lipid sources were calcium salt of palm oil (CaP), pure palm oil (PO), calcium salt of flaxseed (CaFL), calcium salt of sunflower oil (CaSF), flaxseed oil (FLO), and sunflower oil (SFO). Estrous cycles were synchronized in all ewes using 14-day CIDRs followed by 400-IU PMSG injection at the time of CIDR removal. Fertility and lambing percent were higher in ewes fed with diets containing calcium salts of flaxseed and SFO, as compared to other treatments. Total number of lambs in flushing treatments was significantly higher than that in the control group ( p  < 0.01). Serum cholesterol and progesterone levels were significantly greater in omega-3 (CaFL) and omega-6 (CaSF) treatments relative to other treatments ( p  < 0.01). It was concluded that supplementing the flushing diet with calcium salts of fatty acids (CSFA) increased blood metabolites and hormones related to reproductive performance; and improved fertility, lambing rate and ewes of CaFL treatment have the highest number of lambs (16 lambs) between different groups. Using saturated and unsaturated fatty acids, especially in their CSFA forms during flushing period, could improve the reproduction problems induced by progesterone deficiency, lack of durability of the fetus due to hormonal instability, and abortion control factors.

This study aims to investigate the estrus efficacy of FIS (fluorogestone intravaginal sponges)/eCG (equine chorionic gonadotropin) and cloprostenol treatments to establish the optimum protocols for estrus synchronization in ewes. Forty-two ewes were assigned into groups A (FIS/eCG group) and B (CLO (cloprostenol) group). Each group was randomly divided into three subgroups (n = 7) according to the dose of eCG (ECG1, ECG2 and ECG3) or cloprostenol (CLO1, CLO2 and CLO3). The estrus rates, lambing rates and average litter sizes were accounted. Serum concentrations of progesterone (P4), follicle-stimulating hormone (FSH) and luteinizing hormone were determined. Selected optimum schemes were employed in 636 ewes in four sheep farms. Estrus rates of groups A and B were 85.72% and 57.14%. Estrus onset times (EOTs) were 53.91 ± 12.26 and 46.41 ± 4.65 h for groups A and B. EOT of ECG1 was longer than that of CLO3 (P < .05). Lamb numbers, lambing rate and litter size of group B were lower than those of group A. The maximum and minimum lambing rates were calculated in ECG3 and CLO1 (157 vs. 57). On day 11, higher P4 values (P < .05) were determined of ECG3 and CLO1 compared to CLO2 and CLO3 subgroups. FSH concentration of ECG1 was significantly higher than that in group B (P < .05). Application results showed that estrus rate, pregnancy rate and lambing rates of ECG3 and CLO3 protocols were 95.97% vs. 70.91%, 91.37% vs. 88.89% and 149.87% vs 132.69% (P < .05), respectively. FIS/eCG and cloprostenol improved estrus synchronization. Injection of 400 IU eCG after FIS withdrawal was an optimum protocol for estrus synchronization of ewes.

Natural lambing in sheep in Ethiopia 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. Thus, controlling the time of mating artificially using exogenous source of hormones is considered as one of the ways to mitigated problems related to haphazard lambing. To this end, an experiment was conducted to evaluate efficacy of prostaglandin-based estrus synchronization protocol in local and crossbred ewes. A total of 160 ewes (80 local and 80 crossbreds) which lambed at least once and aged 3–5 years were used. Lutalyse® (dinoprost tromethamine sterile solution equivalent to 5 mg dinoprost per ml) and its analog, Synchromate® (cloprostenol sodium equivalent to 0.250 mg cloprostenol per ml), were tested at different doses. The treatments used were intramuscular injection of (1) 2.50 ml of Lutalyse® (12.5 mg dinoprost tromethamine), (2) 2 ml of Lutalyse® (10.0 mg dinoprost tromethamine), (3) 1 ml of Synchromate® (0.25 mg of cloprostenol Sodium), and (4) 0.8 ml of Synchromate® (0.20 mg of cloprostenol Sodium). Forty ewes (20 local and 20 crossbreds) were allocated per treatment. Following injection of the respective hormones, rams of known fertility were introduced into the flock for the duration of 96 h at the ratio of one ram to 10 ewes. All estrus synchronization protocols except treatment 4 (0.8 ml of Synchromate®) induced estrus (heat) in majority (55–65 %) of local and crossbred ewes within 96 h post-hormone injection. The time interval from hormone administration to onset of estrus was also more or less similar for all treatment groups except for treatment group 4 which showed heat quicker. The highest lambing rate was recorded in local ewes (84.62 % (11/13) treated with 2.5 ml of Lutalyse®, whereas the least was obtained in crossbreds (33.33 % (3/9) treated with 0.8 ml Synchromate®. In conclusion, even though 2.5 ml and 2 ml of Lutalyse® or 1 ml of Synchromate® were able to induce heat in majority of local and crossbred ewes, the highest lambing percentage was obtained from ewes treated with 2.5 ml of Lutalyse®. Therefore, the use of 2.5 ml Lutalyse® is recommended to synchronize estrus in local and crossbred ewes under Ethiopian smallholder sheep production system for the benefit of improved lambing rate.

ABSTRACT A field experiment was conducted to investigate the lambing rate, lamb growth and survivability of newborn lambs of pregnant Najdi ewes fed two different total mixed rations (TMR) with different levels of energy and protein viz. higher protein than recommended by National Research Council (1985; TMR1), and higher energy than National Research Council (1985; TMR2) compared with the traditional feeding system of barley and alfalfa hay; Control). A total of 96 Najdi ewes, about nine months old, were divided randomly into three dietary treatments two months before parturition (Late gestation). Lambing percentage, lamb birth weight, lamb weaning weight and mortality rate were recorded. Blood samples were collected regularly during the different stages and analyzed for different important nutritional metabolites. In addition, colostrum, at parturition, and milk samples on day 30, 60 and 90 postpartum were collected for nutrient contents. The results showed an improvement in lambing rate of ewes in T1 and T2 (81 and 80%, respectively) compared to the control (78.8%). Moreover, ewes in T2 showed higher lambs survival rate and average daily gain up to 90 days. There was no significant effect (P>0.05) of treatments on the colostrum composition but milk composition altered by the time interval. Blood metabolites did not vary among the groups, however, urea concentration was significantly (P<0.05) in the T1 and T2 groups. In conclusion, feeding Najdi ewes a diet containing higher energy and protein than recommended by National Research Council (1985), in comparison with the traditional feeding system, improved the lambing rate and growth of the newborns.

The aim of this study was to evaluate the effects of dose and application time of pregnant mare serum gonadotropin (PMSG) on reproductive performance of hair sheep ewes synchronized with fluorogesterone acetate (FGA) under tropical conditions of Northeastern Mexico. Ninety-nine hair ewes (63 Blackbelly and 36 Pelibuey) were treated with intravaginal sponges during 10 days. After insertion of FGA sponges, ewes were divided into four groups, and PMSG was injected intramuscularly at doses of 100, 200, and 400 IU. Relative to FGA sponge removal, PMSG was administrated at −48 h, −24 h, and at sponge removal. PMSG was not administered to the control group. Control ewes had similar ( P  > 0.05) lambing rate, fertility, and fecundity than those treated with 100 IU of PMSG, but lower ( P  < 0.05) percentages to these variables than those treated with 200 and 400 IU of PMSG. Time to estrus decreased linearly, and ovulation rate increased quadratically as PMSG dose increased (0 to 400 IU). Administration of PMSG before sponge removal increased ( P  < 0.01) response to estrus and decreased ( P  < 0.01) interval to estrus compared with control. Ovulation rate, lambing rate, fertility, and fecundity were not affected ( P  > 0.05) by administration time of PMSG. Both dose and time of PMSG application did not affect ( P  > 0.05) pregnancy rate, percentage of single and multiple lambing, and prolificacy. In conclusion, results show that the dose of 400 IU of PMSG administered before sponge withdrawal in an estrus synchronization protocol improved reproductive efficiency of hair sheep ewes.