Variation in the ovine FOXP3 gene and its effect on growth traits in Egyptian Barki sheep.

The aim of the present study was to detect the FOXP3 gene polymorphisms in Barki sheep at a variable region covering exon 13, intron 13 and the coding sequence in exon 14 and to test the association of these polymorphisms with growth traits. 122 Barki lambs were phenotyped for various growth traits, viz., birth weight (BW), weaning weight (WW), pre-weaning daily gain in weight (ADG1), post-weaning daily gain in weight (ADG2) and marketing bodyweight (MW). The polymerase chain reaction - single-strand conformational polymorphisms (PCR-SSCP) and DNA sequencing methods were used to identify the genetic variants in the FOXP3 gene. The associations between the variation in FOXP3 gene and growth traits were tested using a general linear model. Two variants (F1 and F2 with gene frequencies of 0.64 and 0.36, respectively), and three genotypes (F1F1, F1F2 and F2F2 with frequencies of 0.37, 0.53 and 0.10, respectively) were detected. The association of FOXP3 genotype was significant (p < 0.05) with ADG2 and MW. It is concluded that FOXP3 genotype might be helpful for sheep breeders to produce fast-growing lambs. However, further studies are needed in a large population to confirm the association we found.

Association of growth performance and body conformational traits with BMP4 gene variation in Barki lambs.

The objective of this study was to test the association of the variation in a 360 bp region in exon 2 of the ovine bone morphogenetic protein 4 (BMP4) gene with growth performance (birth weight, pre-weaning average daily gain, weaning weight, post-weaning average daily gain and marketing weight) and body conformational traits (height at withers, height at hips, body length, heart girth, thigh circumference, body mass index, skeletal muscle index, body index and relative body index) in 242 Barki lambs using polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). Two variants (A and B) and three genotypes (AA, AB and BB) were detected. The BMP4 genotype significantly affected (p < .05 or p < .01) post-weaning daily gain, marketing weight, height at hips, thigh circumference, body mass index and skeletal muscle index. The results provided valuable information indicating selection for the BMP4 genotype might increase growth and muscularity in Barki lambs.

Polymorphisms in hormone-sensitive lipase and leptin receptor genes and their association with growth traits in Barki lambs.

BACKGROUND AND AIM: Marker-assisted selection has many advantages over conventional selection in animal breeding. The candidate gene approach has been applied to identify genetic markers associated with economically important traits in livestock. This study was established to investigate variation in the hormone-sensitive lipase (HSL) and leptin receptor (LEPR) genes, and their association with growth traits in Barki lambs. MATERIALS AND METHODS: Records for birth weight (BW), pre-weaning average daily gain (ADG1), weaning weight (WW), post-weaning average daily gain (ADG2), and marketing weight (MW) were obtained from 247 Barki lambs. Polymerase chain reaction-single-stranded conformational polymorphism analyses were used to detect variation in exon 9 of HSL and exon 19 of LEPR. General linear models were used to test for associations between the variation in ovine HSL and LEPR, and growth traits. RESULTS: The SSCP banding patterns for HSL showed three variants (H1, H2, and H3), which contained two nucleotide-sequence differences (c.1865C>T and c.2038T>C). Two SSCP banding patterns (L1 and L2) were observed for LEPR and these contained two nucleotide-sequence differences (c.2800G>A and c.2978C>G). The HSL genotype showed no effect on the studied traits. The LEPR genotype was proven to have significant effects (p<0.05) on ADG2 and MW. The presence of the L1 variant was associated (p<0.01) with decreased ADG2 and MW. CONCLUSION: The finding of an association between LEPR gene variation and growth rate after weaning in Barki lambs warrants efforts to improve this trait.

Identification of the association between FABP4 gene polymorphisms and milk production traits in Sfakia sheep.

The aim of this study was to estimate the effect of variation in the fatty acid binding protein 4 gene (FABP4) on milk production traits in Greek Sfakia sheep. Polymerase chain reaction - single-stranded conformational polymorphism (PCR-SSCP) analysis was used to genotype a total of 374 Sfakia ewes for two regions of FABP4 located around exon 2-intron 2 (Region 1) and exon 3-intron 3 (Region 2). Each month, for a period of 6 months, milk samples were collected from the ewes to measure total milk yield, fat content, protein content, lactose content, non-fat solid content, pH, and somatic cell count (SCC). A general linear model was used to test the association between the variation observed in FABP4 and milk production traits. Four gene variants (A1-A4) were found in Region 1 and two variants (C1-C2) were found in Region 2. In the first region, the FABP4 genotype significantly affected ( P < 0.05 ) non-fat solid levels, fat content, and SCC. The presence of the A2 variant was significantly associated ( P < 0.05 ) with decreased SCC, while the presence of A4 was significantly associated with decreased milk yield ( P < 0.01 ), increased non-fat solid content ( P < 0.05 ), decreased fat content ( P < 0.01 ), increased lactose content ( P < 0.05 ), and increased pH ( P < 0.05 ). In the second region, FABP4 genotype had an effect ( P < 0.05 ) on protein content and the presence of the C2 variant was associated ( P < 0.05 ) with increased protein content, decreased SCC, and lower pH. The results suggest an association between variation in ovine FABP4 and milk production traits in Greek Sfakia sheep. Nevertheless, further analyses in independent sheep populations of increased size will strengthen these findings.