Egyptian Sheep Breeds Research Articles

Genetic variations of &#946- and K-casein genes in Egyptian sheep breeds

Objective: Casein genetic polymorphisms are important and well known due to their effects on quantitative traits and technological properties of milk manufacturing. The casein fraction of ruminant milk proteins consists of four caseins, namely 8s1-, 8s2-, &#946-and K-casein. At the DNA level, polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) allow for the simultaneous typing of several alleles at casein loci, as well as the detection of unknown polymorphisms. The genetic polymorphism of two ovine milk protein casein genes, &#946- and K-caseins, was studied in sheep animals belonging to three main breeds reared in Egypt (Rahmani, Barki and Ossimi), as a tool for genetic improvement of milk trait characteristics. Methodology and results: SSCP of &#946-casein exon 7 revealed two different patterns in eighty-five tested animals. The sequence analysis of the PCR product (299-bp) of these two different patterns showed two single nucleotide substitutions; A®C and C®T without any amino acid exchange. The frequencies of these two different patterns were 96.67% and 3.33% in Rahmani; 65.52% and 34.48% in Ossimi and 88.46% and 11.54% in Barki, respectively. The nucleotide sequence of 9-casein in Egyptian sheep was submitted in database NCBI/ GenBank with the accession number JX080379. The polymorphism of Kcasein gene was also detected in eighty-six animals using PCR-SSCP technique. PCR amplified a fragment with 406-bp in exon 4 of this gene. SSCP results showed that all tested sheep animals are monomorphic. The alignment between our sequences with published sequence revealed two nucleotide substitutions; C®T and T®C. The nucleotide sequence of K-casein in our tested animals was submitted in database NCBI/ GenBank with the accession number JX050176. Conclusion and application of findings: This study aimed to identify the genetic polymorphism of &#946 and Kcasein genes, which are strongly related to economically important milk quantitative traits in some Egyptian sheep breeds, as a tool or genetic markers for improvement of these breeds. Key words: Sheep, &#946-casein, K-casein, PCR-SSCP, SNP.

CHANGES IN SOME HEMATOLOGICAL AND SERUM BIOCHEMICAL PARAMETERS DURING THE FIRST WEEK AFTER LAMBING IN SIX CONSECUTIVE PARITIES IN SOME EGYPTIAN SHEEP BREEDS

SUMMARY This study was carried out at the Agricultural Experimental Station, Department of Animal Production, Faculty of Agriculture, Alexandria University. It aimed to determine the effect of breed and parity on some hematological and biochemical parameters during the first week of lactation throughout six consecutive parities in some Egyptian sheep breeds. A total of 108 ewes of three breeds, Barki, Rahmani and Barki x Rahmani crossbreed (36 ewes per each breed and 6 ewes per each parity within breed) were used. Blood samples were collected every other day during the first week of lactation. Results demonstrated that Rahmani and crossbred ewes had higher Hb concentration compared to Barki ewes. There were significant differences (P < 0.05) among all sheep breeds in PCV %. Rahmani ewes had the highest PCV %, while Barki ewes had the lowest values. The crossbred ewes had greater (p < 0.05) MCHC than the other two pure breeds. Hemoglobin concentrations were higher (P < 0.05) in the ewes during the third and fifth parities than those in the other parities, while PCV and MCHC % fluctuated and recorded the highest values in ewes at the fifth and third parities, respectively. Rahmani ewes had greater (P<0.05) serum total protein and albumin concentrations than both Barki and crossbred ewes, while serum total lipids and cholesterol concentrations were higher (P< 0.05) in Barki ewes compared those of Rahmani and crossbred ewes. On the other hand, crossbred ewes showed higher (P<0.05) serum glucose, AST and ALT enzyme activities than the two pure breeds. Ewes, in the third parity, showed greater (P<0.05) serum albumin, cholesterol, AST and ALT than those of other parities. Low serum total protein concentrations were noted in the ewes at the second and third parities. Serum glucose concentrations were high in the first day of lactation, then decreased (P<0.05) sharply from the third day of lactation. Within the first day of lactation, ewes in the first parity recorded the lowest glucose concentrations, which were increased with increasing the parity of the different three breeds. Both Rahmani and crossbred ewes had higher hemoglobin concentrations and PCV % than Barki ewes; this may be reflected on the productivity and adaptability of each breed to their environment.

The effect of backfat thickness at mating on the reproductive and productive performances of ewes

Three Egyptian sheep breeds (Rahmani, n=40; Barki, n=50; Ossimi, n=36) were used to investigate the effect of backfat thickness of ewes, at mating, on their subsequent reproductive and productive performances. Ewes were assigned to four groups, according to their backfat thickness (<1; 1 to <1.5; 1.5 to <2; ≥2mm) respectively. The experimental design was thus completely randomized with the 12 groups arranged factorially (3×4), according to breed and backfat thickness. Ewe breeds did not significantly affect the studied reproductive and productive traits. However, the backfat thickness of the ewes significantly affected all the reproductive and productive traits, except for ewes conceived/ewes joined, and lambs born/ewe lambing. Superior performances were recorded for ewes with a backfat thickness of 1.5 to <2mm and those having ≥2mm – where the lambs weaned/ewe joined increased from 43% in the lowest backfat thickness group (<1mm) to 73% and 77% in the higher backfat thickness groups (1.5 to <2mm and ≥2mm groups, respectively). The kg lamb weaned/ewe joined increased gradually by increasing the backfat thickness of the ewes from 6.2kg in the lowest backfat thickness group, to 14kg in the highest backfat thickness group. However, no significant differences were recorded for ewes with a backfat thickness of 1.5 to <2mm, and those having ≥2mm regarding all the reproductive and productive traits, except for ovulation rate. Therefore, to optimize the profitability in sheep flocks, it is recommended to control the backfat thickness of ewes at mating between 1.5 and 2mm.

Genetic biodiversity studies on IGFBP-3 gene in Egyptian sheep breeds

The insulin-like growth factor binding protein-3 (IGFBP-3) gene is a structural gene associated with the growth and development of the animals. The present investigation was carried out to study DNA polymorphism by PCR-RFLP of IGFBP-3 gene in four Egyptian local sheep breeds and its comparison with Indian sheep breeds. Genomic DNA was isolated from a total of 20 animals from four Egyptian breeds of sheep namely Rahmani, Ossimi, Awassi, and Barki. A fragment of IGFBP-3 gene, comprising of a part of exon 2, complete intron 2, exon 3, and a part of intron 3, was amplified. The amplified fragment was found to be 654 bp in sheep as compared to earlier reports of 651 bp in cattle and 655 bp in buffalo. On digestion of 654 bp with Hae III restriction enzyme yielded single restriction pattern of five fragments of sizes 201, 201, 87, 67, 57 in all the animals belonging to the four Egyptian breeds studied revealing absence of polymorphism in those four Egyptian sheep breeds. On comparison, this fragment was monomorphic in Indian sheep breeds and buffalo ,while it was reported to be polymorphic in cattle.

Fingerprinting of fecB gene in five Egyptian sheep breeds

Recently, many aspects of FecB gene, including reproductive endocrinology, organs development and body mass have been studied. FecB has an additive effect on litter size and ovulation. The present investigation was carried out to study polymorphism by forced PCR-RFLP of FecB gene in five Egyptian local sheep breeds and its comparison with other foreign sheep breeds. Genomic DNA was isolated from a total of 100 animals of Egyptian sheep breeds namely Rahmani, Ossimi, Awassi, Barki and Awassi x Barki crossbred. Forced PCR of the FecB gene 190 base pair (bp) was amplified using specific primer designed to introduc a point mutation in the resulting PCR products with FecB carrier sheep containing an AvaII restriction site (G|GACC), whereas products from noncarriers lacked (of) this site. Digestion of FecB gene 190 base pair with AvaII restriction enzyme resulted in non carrier 190 bp band (wild type) in all the animals belonging to the five Egyptian breeds studied revealing absence of this restriction site in those five breeds. .

Protein Requirements for Maintenance of Egyptian Sheep Breeds

Protein Requirements for Maintenance of Egyptian Sheep Breeds

Breeding activity of two subtropical Egyptian sheep breeds under accelerated lambing system

The breeding performance of Rahmani and Ossimi fat-tailed Egyptian sheep bred every 8 months over 18 successive mating seasons was investigated in five flocks. 5066 and 3740 records on 1127 Rahmani and 830 Ossimi ewes respectively were obtained. Mating was in September, May and January, each mating season lasting 35 days. The results confirm the good breeding activity of the two subtropical breeds under an accelerated lambing system. This system has resulted in 41.9 and 54.7% more lambs weaned per ewe exposed to the ram for Rahmani and Ossimi respectively, compared with a single breeding season each year. The two breeds performed significantly better when bred in September than when bred in May, while the poorest performance was obtained for January matings. The number of lambs born per ewes exposed to the ram was 36 and 28% higher for September than for January matings in Rahmani and Ossimi ewes respectively. Corresponding estimates in the number of lambs marketed at 4 months of age were 38 and 29%. Seasonal variation was higher for fertility than for prolificacy. Pooled data on oestrous activity of Rahmani and Ossimi sheep from 13 trials were analysed. The results indicated that both breeds show oestrous activity throughout the year, though with less activity in spring. Highly significant ( P<0.001) variations in oestrous activity were found between flocks within breeds and between the periods of February to July and August to February. There was less variation in mating activity than in oestrous activity, with some discrepancy in their trends, especially in the spring.