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ABSTRAKFaid-Allah E, Ghoneim E, Ibrahim AHM. 2016. Estimasi komponen varian dan nilai pemuliaan kriteria pertumbuhan pra-sapih pada domba Romney. JITV 21(2): 73-82. DOI: http://dx.doi.org/10. 14334/jitv.v21i2.1353 Penelitian ini dilakukan untuk melihat komponen-komponen ragam, pengaruh genetik langsung, parameter genetik maternal, estimasi nilai pemuliaan (EBV) dan faktor-faktor yang mempengaruhi kriteria pertumbuhan pra-sapih pada domba Romney.

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.

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The objective of this study was to test the association of variation in a 356 bp region in exon 1 of the caprine leptin gene with milk production traits (milk yield (MY), milk fat content (FAT), milk protein content (PRO), milk lactose content (LAC), milk solid not fat content (SNF), pH and somatic cell count (SCC)) in 106 Barki does using polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). General linear model was used to test association between the variation in leptin and milk-production traits. The SSCP banding patterns for leptin revealed two variants (L1 and L2), which contained two nucleotide sequence difference (c.670528A/G and c.670639T/C). The c. 670528A/G substitution results in the substitution of valine with alanine and c.670639T/C results in the substitution of arginine with histidine. Association analysis between the variation in leptin with milk production traits revealed that leptin genotype was associated (P < 0.05) with PRO and highly (P < 0.001) associated with MY. The presence of the L1 variant in the doe genotype was significantly associated with lower MY (P < 0.01) and decreased PRO (P < 0.01), whereas, the presence of the L2 variant in the doe genotype was significantly associated with higher MY (P < 0.05). The detected leptin variants showed significant (P < 0.05) additive effect on pH and highly significant (P < 0.01) dominance effects on MY and PRO. This suggests that selection for the leptin genotypes might increase milk production and milk protein content in Barki goats.