The implications of various gene variant combinations on breeding values for Awassi ewe milk production

Background and Aim: Milk production is an important factor to consider in selecting Awassi sheep. This trait is influenced by various genes that can be managed to boost production. The breeding values (BVs) for milk production in Jordan’s Awassi sheep flocks have been established. This study determined how combined gene variants of BLG, PRL, CSN3, CSN1S1, and CSN2 affect the estimated BVs (EBVs) for milk production in Awassi sheep. Materials and Methods: Milk and blood samples were collected from 391 Awassi sheep, which was then subjected to molecular analysis through sequencing in order to identify potential alleles and genotypes that could be linked to the EBVs of milk. Results: The predicted BVs for milk were significantly influenced by PRL and CSN3 gene variants. Through performing the act of epistasis, the i nteractions of BLG with CSN3 and –CSN1S1 greatly impacted EBVs for milk production. Likewise, the three-way interaction among PRL, CSN3, and CSN1S1, as well as the combined effect of CSN3 with CSN1S1 and CNS1 significantly improved BVs for milk production. When the breeding selection program incorporates the polymorphisms of these genes, gains in milk production can be obtained. Conclusion: Alleles within the examined genomic areas are crucial for evaluating BVs and maximizing genetic gain in milk production

The effects of Saccharomyces cerevisiae supplementation on intake, nutrient digestibility, and rumen fluid pH in Awassi female lambs

Aim: The aim of this study was to evaluate the effect of feeding low (LO)- or high (HI)-fiber diets supplemented with Saccharomyces cerevisiae (SC) on nutrient intake, digestibility, nitrogen balance, rumen fluid pH, and serum concentrations of glucose and urea nitrogen in Awassi female lambs in a 2×2 factorial arrangement of treatments. Materials and Methods: Experimental diets were as follows: (1) LO-fiber diet with no SC supplementation (-LO), (2) LO-fiber diet supplemented with SC (+LO), (3) HI-fiber diet with no SC supplementation (-HI), or (4) HI-fiber diet supplemented with SC (+HI). Eight female lambs were used in a replicated 4×4 Latin square design with 15-day experimental periods (10-day adaptation period and 5-day collection period). Results: A fiber×SC interaction (p≤0.05) was detected for dry matter (DM) and crude protein (CP) intake among diets showing greater DM and CP intake for +LO diet compared to +HI group supplemented with SC, whereas -LO and -HI were intermediate. A fiber×SC interaction (p=0.05) was also detected for the neutral detergent fiber (NDF) intake among diets. Intake of NDF was greater for the -HI diet compared with +LO and -LO diets. Similarly, NDF intake was greater for +HI diet than -LO diet. A tendency (p=0.07) for a fiber×SC interaction was detected for acid detergent fiber (ADF) intake among diets as well. ADF intake tended to be greater for HI-fiber diets. No difference was observed in the rumen fluid pH for lambs fed with the different diets. No fiber×SC interactions were detected for the digestibility of DM, CP, NDF, and ADF among dietary treatments. Digestibility of DM was greater (72.9 g/100 g vs. 67.1 g/100 g; p=0.0002) for LO versus HI fiber. However, NDF and ADF digestibilities were greater (60.8 and 61.9 g/100 g vs. 55.8 and 52.7 g/100 g for NDF and ADF digestibility, respectively; p≤0.01) for the HI-fiber than the LO-fiber diets. Conclusion: Results obtained in the current study indicate that SC supplementation has a minimal effect on the performance of Awassi female lambs fed with varying fiber levels

Growth Performance and Meat Characteristics of the First Awassi–Rambouillet Callipyge Backcross

The Awassi breed is desirable due to its resilient traits, but shows poor lean meat content on the carcass; the callipyge mutation may enhance growth and meat characteristics. The first backcross of callipyge Awassi–Rambouillet (CRAW) lambs was generated by mating Awassi ewes with heterozygous F1 (50 % Awassi and 50 % Rambouillet) rams for the callipyge mutation. A fattening trial with carriers of CLPG (CRAW), non-carriers (RAW), and Awassi (AW) ram lambs was conducted for 94 days and growth and meat characteristic parameters were recorded. Final body weight, average daily gain (ADG), feed conversion ratio, and dry matter intake, but not initial body weight, were greater in CRAW and RAW lambs as compared to AW lambs; hot and cold carcass, dressing percentage, and shoulder, rack, and loin weights were greater in CRAW vs. AW but not RAW lambs. Leg cuts were heavier in CRAW vs. both RAW and AW lambs; intermuscular and subcutaneous fat percentages were greater in CRAW as compared to AW but not RAW lambs. Non-carcass components showed kidney fat, kidney, liver and testes weights higher in CRAW lambs as compared to AW lambs, but these parameters were similar to those of RAW lambs. There were no differences in fat tail weight. Further, CRAW lambs had higher shear force and water holding capacity than RAW and AW lambs, while cooking loss was the lowest in CRAW lambs. In conclusion, the callipyge mutation with 25% Rambouillet genes can provide efficient improvements in growth and meat characteristics, with the exception of tenderness in Awassi sheep

Duplication in ECR near HMX1 and a SNP in GATA6 Genes Regulate Microtia in Awassi Sheep

Microtia and anotia are hereditary traits characterized by an underdevelopment or complete absence of the outer ear. These congenital malformations observed in many species can exist as part of various syndromes or as an isolated trait as seen in the fat-tailed Awassi sheep breed. Our study aims to identify the genetic mutations causing microtia in Awassi sheep by DNA sequencing. DNA was extracted from blood samples randomly collected from 84 Awassi sheep (16 earless, 41 short ear and 27 normal ear) across different farms. GATA6 exons 1, 2, 4, 6 and 7, CLRN1 intron 3, DCC intron 2, ECR near HMX1 and the intergenic region between GATA6 and MIB1 genes were screened, amplified and sequenced. Allele and genotype frequencies were calculated by direct counting. Association was performed using chi-squared test for goodness-of-fit. Results showed mutations in only two genes significantly associated with microtia in Awassi: duplication in part of ECR near HMX1 (6:114293121-6:114293196) and a SNP at GATA6 exon 7 (23:34498242). Association results revealed that the ECR locus accounts for the microtia phenotype, while GATA6 exon 7 acts as a modifier gene. Genetic screening for these loci can be used to improve selection against microtia in Awassi sheep

Relationships between Hha1 Calpastatin Gene Polymorphism, Growth Performance, and Meat Characteristics of Awassi Sheep

Advances in molecular genetics have allowed the identification of genes that can enhance livestock production. The aim of this study was to investigate possible relationships between the calpastatin (CAST) Hha1 gene polymorphisms and growth performance, carcass characteristics, and meat quality in Awassi sheep. A total of 87 blood samples were collected from two-week-old Awassi ram lambs. The amplification of the CAST Hha1 gene yielded a fragment of 622 bp. Three CAST genotypes were found in Awassi sheep: MM for two fragments (385 bp and 281 bp), MN for three fragments (622 bp, 385 bp, and 281 bp), and NN for only one fragment (622 bp). The M and N allele frequencies of the CAST Hha1 genotypes were 0.765 and 0.235, respectively, while the genotypic frequencies of MM, MN, and NN were 0.586, 0.356, and 0.057, respectively. Based on CAST Hha1 gene polymorphisms, three groups of lambs (MM: n = 8; MN: n = 6; and NN: n = 3 genotypes) were subjected to a fattening period of 70 days to investigate growth performance and meat characteristics. Only the final body weight and longissimus muscle width were significantly different between the three genotypes, while no significant differences were detected in any other carcass characteristics and meat quality parameters. In this study, new variants were observed in CAST using the Hha1 restriction site, potentially assisting in Awassi sheep breeding and selection programs to improve final body weight and longissimus muscle width

Growth performance and meat characteristics of the first filial Awassi Rambouillet callipyge ram lambs

Aim: This study was designed to introduce the callipyge (CLPG) and 50% of Rambouillet sheep genes to improve meat quality and quantity of Awassi (AW) sheep. Materials and Methods: The CLPG mutation was introduced into the AW sheep through frozen semen of homozygous Rambouillet rams for the CLPG mutation. Four ram lambs from the first-generation Rambouillet callipyge Awassi (F1-RCA) and five from pure AW were recruited for a fattening trial conducted in individual pens using standard ration, following which ram lambs were slaughtered for carcass and meat evaluation. Results: Final body weight, dry matter intake, average daily gain, and feed conversion ratio were significantly higher in F1-RCA than AW. Hot and cold carcass weights and the other carcass cuts' weights, except for the fat tail, were heavier in F1-RCA than AW. There was no difference in dressing percentage between the two genetic groups (p>0.05). All non-carcass components' weights, except spleen, kidney, and testis, were higher in F1-RCA. Total lean, total bone, and intermuscular fat weight were greater in F1-RCA, but bone-to-lean ratio was lower in F1-RCA when compared with AW (p0.05) were observed in all meat quality parameters for muscle longissimus with the exception of pH, redness color, and tenderness that were lower (p<0.05) in F1-RCA than AW. F1-RCA lambs had larger longissimus muscle area (30.9 vs. 16.9 cm2) and less leg fat depth (11.1 vs. 17.4 mm). Conclusion: The implications of this research show the potential of 50% of Rambouillet genes and the CLPG mutation to improve growth and meat characteristics in AW-Rambouillet crosses and can be used further to develop a meat-type AW with improved productivity and muscle mass

Genetic diversity and population structure of local and exotic sheep breeds in Jordan using microsatellites markers

Aim: This study was conducted to study the genetic and population structure of local (Awassi) and exotic (Romanov, Charollais, Assaf, Awassi, and Suffolk) sheep breeds in Jordan using eight microsatellite markers. Materials and Methods: A total of 125 sheep were used (25 from each breed) in the study. The number of alleles (A), the mean values of observed (Ho) and expected (He) heterozygosity, polymorphism information content (PIC), fixation index as a measure of heterozygote deficiency or excess, and Hardy-Weinberg equilibrium (HWE) were analyzed using PopGen and CERVUS softwares. Nei's standard genetic distances among breeds and dendrogram of unweighted pair group method with arithmetic mean (UPGMA) were calculated and constructed using PopGen software. Results: A total of 40 alleles were detected with an average number of alleles of 5. The mean Ho value was higher than the mean He value for all breeds. Awassi breed showed the highest average PIC value while Romanov had the lowest. There was a significant (p<0.05) deviation from HWE at each locus within and between breeds. Deviations from HWE were found to be highly significant for all markers except OARFCP304 locus. The genetic distance estimates revealed a close relationship between Romanov and Charollais and between Awassi and Charollais. In the UPGMA dendrogram, Charollais, Romanov, and Awassi breeds were placed together in one main cluster while Assaf was in a different subcluster. Awassi was placed alone in a second main cluster. Conclusion: Results of this study offer insight toward the genetic conservation of the studied breeds and a base on which breeding plans can be made

G1 point mutation in growth differentiation factor 9 gene affects litter size in Sudanese desert sheep

Background and Aim: Sudanese desert sheep encompass different sheep breeds named according to the different Sudanese tribes that rear them such as the Dubasi, Shugor, and Watish sheep. The objectives of this study were to screen for G1 point mutation in the polymorphic growth differentiation factor 9 (GDF9) gene, investigate its association with litter size, and construct the phylogeny of the different tribal breeds that belong to the Sudanese Desert sheep tribal types. Materials and Methods: Genomic DNA was extracted from whole blood of three tribal Desert sheep breeds (Dubasi, Watish, and Shugor) using the guanidine chloride method. Polymerase chain reaction-restriction fragment length polymorphism with HhaI restriction enzyme and sequencing techniques was used for genotyping the GDF9 locus for possible mutations associated with litter size in the three desert sheep tribal types. Results: G1 mutation in GDF9 caused the replacement of Arginine by Histidine at residue 87. The wild type allele (A) had the highest frequency, whereas the mutant type allele (a) had the lowest in all the sequenced subtypes. The genotype frequencies of the wild type ewes (AA) were higher than the heterozygous (Aa) and the mutant type (aa) frequencies in the three studied desert sheep types. No significant differences were found in the allele frequency between the three tribal types. Litter size was significantly influenced by the genotypes of GDF9 gene, parities, and subtypes (p≤0.01, 0.01, and 0.05, respectively). In the Watish sheep type, heterozygous sheep in their second parity recorded the highest litter size. Sequence alignment of GDF9 gene samples with the database entry indicated that all three tribal types were similar and identical to the reference sequence. The phylogenetic tree revealed that Shugor is the common ancestor of the studied types and Watish is more closely related to Shugor than Dubasi. This result mi ght partly explain the lower reproductive performance of Dubasi compared to Watish and Shugor. Conclusion: The presence of one copy of GDF9 gene increased litter size in the studied Sudanese Desert sheep. This locus may be used as a biomarker for litter size improvement through genotypic selection and allele or gene introgression

Genetic polymorphisms of fecundity genes in Watish Sudanese desert sheep

Background and Aim: The Watish sheep is a strain of desert sheep of smaller size compared to other desert sheep ecotypes, and there is anecdotal evidence that it is endowed with high litter size. The present study was designed for screening for polymorphisms in the known fecundity genes (bone morphogenetic protein receptor type 1B A<G in exon 6, bone morphogenetic protein 15 (BMP15) (FecXB, FecXG, FecXH, and FecXI) in exon2, growth differentiation factor 9 (GDF9) – G1 in exon1 and G8 in exon2 and PRLG<A in intron2) and their association with litter size in Watish. Materials and Methods: The study involved 156 Watish ewes of 2-6 years of age, along with data on litter size in the first, second, and third parity from Sinnar state and contiguous Blue Nile State. Genomic DNA was isolated and genotyped using polymerase chain reaction-restriction fragment length polymorphism. Allele and genotype frequencies were calculated by direct counting. Chi-square test for goodness of fit was performed for agreement with Hardy-Weinberg expectations and association testing. Results: The results demonstrated that all individuals were non-carriers for the target mutations of FecB, BMP15 (FecXB, FecXH, and FecXI), and GDF9-G8. With regard to the GDF9-G1 gene, the genotypic frequencies were 0.07% (G+) and 0.93% (++), in FecXG gene they were 0.993% (++) and 0.006% (B+), in PRL gene 0.516(++), 0.347(B+), and 0.137(BB). The Chi-square test showed a non-significant association between ewe's type of birth and the detected mutations genotypes. Conclusion: These results preliminarily indicated that GDF9-G1, BMP15 (FecXG), and PRL genes might have had some contribution for improving litter size in Watish Sudanese sheep. However, further studies using larger samples are needed to detect the effects of those mutations on Watish sheep litter size