Twin Ewes Research Articles

Live weight peculiarities of the Tsigai breed young sheep during the suckling period in connection with the terms of sheep ewes’ gestation

The correlation of the Tsigai breed ewes’ gestation period with the patterns of growth and development of the sheep growing stock during the suckling period was explored in the article. The dates of inseminations and calvings were selected for analysis to calculate the duration of ewes' gestation and indicators of live weight of young animals at birth and at weaning with subsequent calculation of correlations between these traits. The average duration of the ewes’ gestation period is 157.76 ± 0.61 days (Cv=7.6%). The single-born ewe lambs of the No. 01684 line were higher in live weight by 6.9% (р ≤ 0.001), and higher in average daily gain by 6.0% (р ≤ 0.001) than the sample averages at weaning. The single-born ram lambs the No. 80077 line have a significant advantage in terms of live weight at weaning by 9.1% (р ≤ 0.01), and in terms of average daily gains by 11.8% (р ≤ 0.05). Single-born ram lambs of the No. 01684 and No. 66796 lines with a reduced live weight at birth grow more intensively: a significant advantage in terms of live weight at weaning and average daily growth, respectively, is 12.1% (р ≤ 0.001) and 9.6 % (р ≤ 0.01) higher in comparison with the average sample values. Twin ewe lambs of the No. 80077 line with a lower live weight at birth by 0.2% and an increased weight at birth by 0.4, the difference of which is also not reliable, nevertheless have a significant advantage in average daily growth compared to the average – by 9.1% (р ≤ 0.001), while the twin ram lambs have no significant difference in the indicators of the suckling period. Milkiness is negatively associated with the duration of pregnancy of ewes and positively with the lambs live weight at weaning period. In order to establish a line for increased multiplicity, it is necessary to select ewe lambs to be used in the replacement stock from twin litters in the line No. 80077. The increased live weight of young animals from single litters is formed by the parent livestock of No. 01684, 20832, 65204 and 80077 lines. The advantage of twin ram lambs in terms of live weight over the average values has not been proven.

Novel single nucleotide polymorphism G216A of hormone-sensitive lipase gene associated with Awassi sheep reproduction

BackgroundLitter size plays a crucial role in determining profitability in the sheep industry. Breeding sheep with high litter sizes could be enhanced by selecting candidate genes. One gene affecting sheep's reproductive performance is the hormone-sensitive lipase (HSL) gene. As a result, this study investigated whether the HSL gene variation influenced the fertility of Awassi ewes. The genomic DNA was extracted from 52 singleton ewes and 48 twin ewes. The HSL gene exon 9 (278 bp) was amplified using polymerase chain reaction (PCR).ResultsStudy results revealed two genotypes identified in the 278-bp amplicons: GG and GA. Molecular sequence analysis identified a novel mutation in the GA genotype 216G > A. The statistical analysis revealed a significant association between the single nucleotide polymorphism (SNP) 216A > G and reproductive performance. Ewes with the SNP 216G > A genotype exhibited significantly increased litter sizes, twinning rates, lambing rates, and fewer days to lambing compared to ewes with GG genotypes (P ≤ 0.05). The logistic regression analysis results provided strong evidence that the 216G > A mutation significantly increased litter sizes.ConclusionsThis study concluded that variant 216G > A SNP positively impacts Awassi sheep reproduction. There is a higher litter size and more prolificacy in ewes with the 216G > A SNP than in those without the SNP.

The novel C268A variant of BMP2 is linked to the reproductive performance of Awassi and Hamdani sheep.

Prolificacy-associated genetic markers can be utilized to enhance litter size in the sheep breeding industry. Sheep reproduction is influenced by a multitude of genes, including bone morphogenetic protein 2 (BMP2). This study aimed to explore the potential relationship between variability in the BMP2 gene and reproductive performance in Awassi and Hamdani ewes. The genomic DNA was extracted from 99 single-progeny ewes and 101 twin ewes. Polymerase chain reaction (PCR) was employed to produce an amplicon consisting of four sequence fragments: 277bp, 251bp, 331bp, and 340bp, from exons 1, 2, 3, and 4 of the BMP2 gene, respectively. Three genotypes were identified for amplicons in exon 4 with 340-bp lengths: CC, CA, and AA. Upon analyzing the sequence of the CA genotype 382C > A, a novel mutation was discovered in this genotype. A robust association was identified between the single nucleotide polymorphisms (SNP) 382C > A and reproductive performance through statistical analysis. An important distinction was discovered between ewes carrying SNP 382C > A and those carrying CC in terms of litter sizes, twinning rates, lambing rates, and days to lambing. An analysis of logistic regression revealed a significant association between litter size and the 382C > A SNP. There was a decrease in lamb production among ewes with the CC genotype compared to those with the CA and AA genotypes. These results indicate that the SNP variant 382C > A has a positive influence on the reproductive performance of Awassi and Hamdani sheep. Sheep carrying the 382C > A SNP exhibit increased litter size and overall productivity compared to those without the SNP.

Reproduction of Awassi and Hamdani Sheep Is Associated With a Novel Missense SNP (p.24Ile>Thr) of the GnIH Gene.

Litter size is a crucial economic factor in the sheep industry. Several factors and genes influence litter size, making the identification of genes or loci involved a genetic challenge. Gonadotropin-inhibitory hormone (GnIH) is one of several genes that influence sheep's reproductive traits. Thus, this study aimed to investigate whether variations in the GnIH gene affect the reproductive performance of Awassi and Hamdani ewes. DNA was extracted from 99 single-progeny ewes and 101 twin ewes. The polymerase chain reaction (PCR) produced amplicons of 262 bp, 275 bp, and 284 bp from exons 1, 2, and 3 of the GnIH gene. Single-strand conformational polymorphism (SSCP) technique was used for genotyping experiments. Sequencing and in silico analysis were performed on each set of SSCP-resolved bands. Two genotypes of 262 bp amplicons were found: TT and TC. Sequence analysis revealed a novel missense mutation in the TC genotype at position c.122T>C. Five in silico tools were used to assess the impact of this mutation on GnIH protein structure, function, and stability, all of them demonstrated a deleterious effect. An analysis of statistical data revealed a strong correlation between the c.122T>C single-nucleotide polymorphism (SNP) and reproductive performance. Ewes with the SNP 122T>C exhibited a significant increase in litter size, twinning rates, lambing rates, and days to lambing when compared with ewes with the TT genotype. A lower number of lambs were born to ewes with the TT genotype than those with the TC genotype. These results concluded that the c.122T>C SNP variant positively influences the reproductive performance of Awassi and Hamdani sheep. Sheep that carry the c.122T>C SNP show higher litter size and increased productivity.

Litter size affects ovulation and pregnancy rate after a hormonal treatment without influencing expression of estrus in the anestrous season in ewes

The aim of this study was to determine if litter size affects the response to hormonal treatments for inducing estrus and ovulation during the non-breeding season. A total of 124 Corriedale ewes were utilized, consisting of 56 ewes that had given birth during the spring and were currently nursing either a single lamb (Single, n = 30) or twin lambs (Twin, n = 26). Additionally, a control group of ewes that had not given birth (Con, n = 68) was included. Estrus was induced 38 days after lambing using intravaginal sponges containing medroxyprogesterone acetate, which were left in place for 7 days. Furthermore, 350 IU of eCG was administered at the time of sponge removal. Upon detection of estrus, the ewes were inseminated, and transrectal ultrasonography was performed 8 and 40 days later to determine the presence of a corpus luteum (CL) and pregnancy, respectively. Expression of estrus did not differ due to postpartum status. However, a higher proportion of Con ewes than Twin ewes had a corpus luteum (P = 0.02), while the Single group did not differ from the other groups. Conception and pregnancy rates were higher in the Con group than in both, the Single and Twin groups (P ≤ 0.03). The litter size did not have a significant effect on the estrous response; however, postpartum status and/or lactation negatively impacted the pregnancy outcome.

Association of Novel C319T Variant of PITX2 Gene 3'UTR Region With Reproductive Performance in Awassi Sheep.

Several genes influence sheep's reproductive performance, among them the paired-like homeodomain transcription factor 2 (PITX2) gene. Thus, this study aimed to examine whether the variability within the PITX2 gene is associated with the reproductive performance of Awassi ewes. A total of 123 single-progeny ewes and 109 twin ewes were used to extract genomic DNA. An amplicon of 4 sequence fragments from exons 2, 4, 5 (upstream portion), and 5 (downstream portion) of the PITX2 gene was generated by polymerase chain reaction (PCR), 228, 304, 381, and 382 bp, respectively. Three genotypes of 382 bp amplicons were identified: CC, CT, and TT. Sequence analysis revealed a novel mutation in the CT genotype 319C > T. Statistical analysis revealed that single-nucleotide polymorphism (SNP) 319C > T was associated with reproductive performance. Single-nucleotide polymorphism 319C > T-carrying ewes had significantly (P ⩽ .01) lower litter sizes, twinning rates, lambing rates, and more days to lambing than those carrying CT and CC genotypes. Based on a logistic regression analysis, it was confirmed that the 319C > T SNP decreased litter size. Ewes with TT genotype produced fewer lambs than ewes with CT and CC genotypes. According to these results, the variant 319C> T SNP negatively affects the reproductive performance of Awassi sheep. Ewes carrying the 319C > T SNP have a lower litter size and are less prolific than those without the SNP.

A Missense p.Q>R234 Mutation in the Osteopontin Gene Is Associated With the Prolificacy of Iraqi Awassi Ewes.

One of the most valuable traits in production and breeding is a sheep's prolificacy which is influenced by several genes, one of which is the osteopontin (OPN) gene. Thus, this study aimed to determine the effect of genetic variation within the OPN gene on Awassi ewe prolificacy. Genomic DNA was extracted from 123 single-progeny ewes and 109 twin ewes. Polymerase chain reaction (PCR) was used to amplify 4 sequence fragments (289, 275, 338, and 372 bp), representing exons 4, 5, 6, and 7 of the OPN gene. A 372 bp amplicon was identified with 3 different genotypes: TT, TC, and CC. Sequence analysis revealed a novel mutation in TC genotypes p.Q>R234. Statistical analysis revealed that the single nucleotide polymorphism (SNP) p.Q>R234 was associated with prolificacy. Ewes carrying the p.Q>R234 SNP had significantly (P ⩽ .01) lower litter sizes, twinning rates, and lambing rates, and more days to lambing than those with the TC and TT genotypes. The p.Q>R234 SNP was confirmed to be responsible for lower litter size through logistic regression analysis. From these results, we can conclude that the missense variant p.Q>R234 adversely affects the traits of interest and shows that the p.Q>R234 SNP negatively influences the prolificacy of Awassi sheep. Based on this study, it is evident that ewes in this population carrying the p.Q>R234 SNP have a lower litter size and are less prolific.

A Novel c.100C > G Mutation in the FST Gene and Its Relation With the Reproductive Traits of Awassi Ewes.

Reproductive traits are affected by many factors, including ovarian function, hormones, and genetics. Genetic polymorphisms of candidate genes are associated with reproductive traits. Several candidate genes are associated with economic traits, including the follistatin (FST) gene. Thus, this study aimed to evaluate whether the genetic variations in the FST gene are associated with the reproductive traits in Awassi ewes. The genomic DNA was extracted from 109 twin ewes and 123 single-progeny ewes. Therefore, 4 sequence fragments from the FST gene were amplified using polymerase chain reaction (PCR) (exon 2/240, exon 3/268, exon 4/254, and exon 5/266 bp, respectively). For a 254 bp amplicon, 3 genotypes were identified: CC, CG, and GG. Sequencing revealed a novel mutation in CG genotypes c.100C > G. The statistical analysis of c.100C > G showed an association with reproductive characteristics. Ewes carrying the c.100C > G had significantly (P ⩽ .01) lower litter sizes, twinning rates, lambing rates, and more days to lambing compared with CG and CC genotypes. Logistic regression analysis confirmed that the c.100C > G single-nucleotide polymorphism (SNP) is responsible for decreasing litter size. According to these results, the variant c.100C > G negatively affects the traits of interest and is associated with lower reproductive traits in Awassi sheep. As a result of this study, ewes carrying the c.100C > G SNP have lower litter size and are less prolific.

Fetal programming by co-twin rivalry in sheep1

Fetal rivalry for space and nutrients compromises intrauterine environment and fetal growth, this leading to further consequences during adult life (i.e., fetal programming). Focusing on sheep, relevant fetal programming effects have been revealed on body composition and growth although little is known about their potential impact on the reproductive performance of adult ewes. This research focused on the analysis of fetal programming-related effects on 41,475 litter size (LS) records from 7,177 purebred Ripollesa ewes. Fetal programming sources of variation accounted for the linear and quadratic effect of absolute birth BW (ABBW), relative birth BW (RBBW) of twin-born ewes (i.e., both magnitude and direction of the birth BW difference between the ewe and its co-twin), and sex of twin ewe's littermate (SLM). More specifically, data were analyzed under a threshold mixed model and the statistical relevance of models accounting for different combinations of ABBW, RBBW, and SLM effects was compared by Bayes factors (BF; i.e., the ratio between the posterior probability of 2 competing models). The model accounting for RBBW and discarding both ABBW and SLM effects was clearly preferred; its posterior probability was 35.2 to 362.3 times higher than from remaining models and provided very strong (31.6 < BF < 100) and decisive evidences (BF > 100) supporting the relevance of RBBW and the negligibility of both ABBW and SLM. Single-born ewes were included as reference group and they reached a predicted LS of 1.189 lambs per lambing. Twin-born ewes being >600 g lighter than their co-twins suffered from an impaired reproductive ability with 1.162 lambs per lambing (95% credible interval [95CI], 1.147 to 1.179), and this estimate increased until ewes were 151 to 300 g lighter than their co-twins (1.226 lambs per lambing; 95CI, 1.208 to 1.244). Remaining categories (i.e., ewes being heavier or equal than their co-twins) did not provide significant differences and showed an enhanced reproductive ability of approximately 1.23 lambs per lambing. These significant differences in LS highlighted the influence of fetal programming in sheep under rangeland conditions, which implies decisive economic consequences worldwide. Moreover, these results could contribute additional information on twin biology, which could be useful in other mammalian species such as humans.

Transplacental transfer of medetomidine and ketamine in pregnant ewes

The extent of placental transfer of medetomidine and ketamine is unknown in pregnant ewes. Date-mated singleton (n = 8) and twin (n = 8) pregnant merino cross ewes were anaesthetized for Caesarean delivery of preterm lamb fetuses. A combination of medetomidine (20 μg/kg) and ketamine (10 mg/kg) was administered by intravenous injection and surgery performed immediately thereafter. Blood samples were collected from the ewe at one, five and 10 min after intravenous injection and from the umbilical vein of the fetus at delivery. Non-pregnant ewes were also anaesthetized (n = 8). There was no difference in the plasma concentration of medetomidine or ketamine when comparing singleton and twin ewes or pregnant and non-pregnant ewes for the short duration of the study. Fetal plasma concentrations of each drug were comparable to the maternal concentrations at the same time. We conclude that both drugs cross the placenta readily and provide anaesthesia and analgesia for the fetus when it is delivered.

Can a herb and white clover mix improve the performance of multiple-bearing ewes and their lambs to weaning?

The productive performance of highly fecund ewes and their progeny on ryegrass-based swards is limited in late pregnancy and lactation. Alternative herbages, such as chicory, plantain and red and white clover, have the potential to improve performance levels. In the present study, 49 twin- and 42 triplet-bearing Romney composite ewes bred to either Suffolk or Romney rams were allocated to one of three nutritional treatments from Day 131 of pregnancy [19 twin ewes on a ryegrass–white clover sward mix (Rye/WC); 16 twin ewes on a plantain–ryegrass sward mix (Plant/Rye); 14 twin ewes on a chicory–plantain–red and white clover sward mix (Herb); 13 triplet ewes on Rye/WC; 16 triplet ewes on Plant/Rye; and 13 triplet ewes on Herb] and remained on these sward treatments with their lambs until 75 days after the midpoint of the lambing period (L75). Nutritional treatment had no effect (P &gt; 0.05) on ewe liveweight, body condition score (BCS) or non-esterified fatty acid and β-hydroxybutyrate concentrations on Day 145 of pregnancy. At L75, ewes on the Herb treatment sward were heavier than ewes on Plant/Rye (70.75 ± 1.31 v. 61.43 ± 1.28 kg, respectively) and had a higher BCS than ewes on either Plant/Rye or Rye/WC (2.7 ± 0.1, 2.2 ± 0.1 and 2.3 ± 0.1, respectively). Sire type and nutritional treatment had no affect (P &gt; 0.05) on lamb birthweight or weight at L75. At L20, lambs born to ewes on the Herb sward treatment were heavier than those on the Rye/WC and Plant/Rye treatments (8.74 ± 0.23 v. 7.98 ± 0.23 and 7.79 ± 0.22 kg, respectively; P &lt; 0.05). Neither birth rank, sire type nor ewe treatment had any effect (P &gt; 0.05) on maximum heat production on a per kg liveweight basis or total heat production. Romney-sired lambs on the Herb sward treatment had higher (P &lt; 0.05) survival rates than those on the Rye/WC sward treatment (97.8% v. 61.7%, respectively). However, no such relationship was observed in lambs born to Suffolk sires (79.8% v. 84.8%, respectively). The survival response resulted in greater (P &lt; 0.05) total liveweight of Romney-sired lambs at L75 per ewe on the Herb nutritional treatment than on the Rye/WC treatment (61.6 ± 5.0 v. 36.7 ± 4.6 kg, respectively) a relationship not observed (P &gt; 0.05) in Suffolk-sired lambs. In conclusion, the present study indicates that there is the potential to improve the productive performance of multiple-bearing ewes and their lambs by grazing on a Herb sward mix.

Effects of dam parity and rearing rank on the glucose and fat metabolism, and adrenal function of post-pubertal single and twin-ewe progeny

In an effort to increase the number of lambs produced per ewe’s productive lifetime in New Zealand, an increasing number of ewe lambs (8–9 months old) are being bred. This, in turn, results in an increased proportion of second-parity 2-year-old ewes in New Zealand’s breeding flock, rather than the more usual first-parity 2-year olds. The longer-term effects of dam parity on resulting ewe progeny are of interest and few studies have examined this. The present study was designed to determine whether parity (first or second) of Romney 2-year-old dams had any effect on the metabolic function of their single- and twin-born and reared ewe lamb progeny at 10 months of age. Ten-month-old, single and twin ewe lamb progeny born to first- or second-parity dams (n = 8 per group) were catheterised and given intravenous glucose (0.17 g/kg liveweight) (GTT), insulin (0.15 IU/kg liveweight) (ITT) and epinephrine (1 μg/kg liveweight) (ETT) tolerance tests to assess their glucose and fat metabolism and adrenal function. Rearing rank reduced (P &lt; 0.05) the insulin response of twins to a glucose challenge, but increased (P &lt; 0.05) their glucose response to an insulin challenge. Offspring from first-parity dams had higher (P &lt; 0.05) basal plasma concentrations of cortisol and cortisone, whereas their cortisol/cortisone responses to an insulin challenge were unaffected by either dam parity or rearing rank. Neither dam parity nor rearing rank appeared to influence responses to an epinephrine challenge. The present study suggests that both dam parity and rearing rank alter the glucose and insulin metabolism of the offspring, which may have longer-term impacts on the growth and reproductive efficiency of the animal.

屋外の柵内における春季および夏季のサフォーク種双子成雌羊の個体間距離

屋外の柵内における春季および夏季のサフォーク種双子成雌羊の個体間距離

Passage through the rumen and the large intestine of sheep estimated from faecal marker excretion curves and slaughter trials

External digesta markers (Yb-labelled diets and Co-EDTA) were given orally as a pulse dose to four pairs of Rasa Aragonesa twin ewe lambs, fed on either chopped or ground and pelleted lucerne hay, in order to estimate slow (k1) and fast (k2) rates of passage of liquid and solid phase from faecal marker excretion curves. After the faecal sampling period daily doses of the same markers were infused continuously for 5 d and the animals slaughtered. Concentrations of markers in the different compartments of the gut were determined and used to calculate mean retention times. The results showed that the rumen and the large intestine were the two main mixing compartments of the gut, accounting for more than 95% of total mean retention time. Rates of passage estimated from faecal marker excretion did not accurately represent marker kinetics in the compartments of the gut derived from slaughter data. Accuracy in the estimation of fractional outflow rate from rumen (kR) by k1 was higher for low values of kR whereas k2consistently overestimated large intestine outflow rate (kLI), especially for high values of kR. The relationship between outflow rates from the main two mixing compartments was important in influencing the accuracy of prediction of faecal estimates.

Selection for reproduction rate in Australian Merino sheep: direct responses

Selection for reproduction rate in Australian Merino sheep: direct responses

Effect of Body Weight of Ewes on Subsequent Lamb Production

Birth and weaning weight records of 962 and 805 spring-born lambs, respectively, were analyzed. Age of dam did not significantly affect weight of the lambs at birth, but the 2- and 7-year-old ewes tended to wean lighter lambs. Sex and type of birth of the lambs exerted the most pronounced effect of the factors studied. Twin lambs weighed 0.76 and 7.1 kg. less than single lambs at birth and weaning, respectively. Twin ram lambs were 0.59 and 1.8 kg. heavier at birth and weaning than twin ewe lambs. There was a 5.63-kg. increase in weaning weight with each kilogram increase in birth weight. The greatest response of weaning weight to increase in birth weight occurred in the single lambs. The body weight of the ewes markedly affected weaning weight and to a lesser degree the birth weight of lambs. As the body weight of ewes increased, there was a significant increase in weaning weights of lambs. The heaviest ewes (59.5 to 63.6 kg.) produced heavier lambs at birth and at weaning than did other ewes in this study. An increase in the ewes' body weight of 1 kg. resulted in a 0.1-kg. increase in weaning weight of lambs.

Selection for weaning weight in Merino sheep. 2. Correlated responses in other production characters

The heritabilities of seven production characters of Merino Sheep and their phenotypic and genetic correlations with corrected weaning weight have been calculated using half-sib and dam-daughter correlations. Realized genetic correlations calculated from responses in Weight Plus and Weight Minus selection flocks, which showed broad agreement with these correlations, were : 17-month body weight, 0.72 ; yield, 0.22 ; clean fleece weight, 0.24 ; and staple length, 0.17. There was zero relationship with greasy fleece weight and crimps per inch, and a large negative relationship between folds and high weaning weight. There were strong phenotypic correlations between lamb growth and milk production through the total weight of milk protein produced. The lamb's genotype was the most important contributor to the difference in weaning weight between the flocks. There were no differences in reproductive performance or survival rates between the flocks but twice as many twin rams and 20 per cent more twin ewes were mated in the Weight Minus flock over the selection period.

Production of Antihormones by Prolonged Administration of Pituitary Extract. Effect on Anterior Hypophysis

A cytological study has been made of the hypophyses of 2 dogs and 2 sheep which had received prolonged injections of extracts of sheep-pituitary glands, and of 2 dogs that had been injected with antihormone-serum. The striking physical changes in one of the dogs, namely, an atrophy of the thyroid, adrenals and gonads, a cessation of growth, and the development of obesity, have been reported elsewhere. The 2 dogs which were injected subcutaneously with the sheep-pituitary extract for 4 and 7 months respectively, developed anti-hormones which inactivated not only the injected pituitary extract, but also several of the hormones of their own hypophyses. The 2 dogs which were injected daily with 10 cc of canine antihormone-serum showed signs of moderate inactivation of the gonads, thyroids and adrenals. Twin ewes were injected with sheep-pituitary extract daily for 6 months. Their genitalia and mammary glands continually showed signs of activation, and at autopsy their gonads and uteri were found to be stimulated. No gonadotropic antihormone developed. A half-sister of these ewes served as a control. The hyophyses of the dogs injected with sheep-pituitary extract. The basophile cells show the most striking abnormalities consisting of: (1) a great increase in the size and number of the basophiles; (2) an excessive clumping and liquefaction of cytoplasmic granules; (3) the formation of many vacuoles of 3 different types: (a) clear round spaces containing a non-stainable substance or one removed by the technic employed; (b) scattered clear pale blue vacuoles which in some of the basophiles coalesced to become extensive vacuolar inclusions; (c) scattered deeply basophilic vacuoles which in some cells displaced the cytoplasm almost entirely.