The variability of the promoter region and the 3′UTR (exon-7) of the BLG gene, encoding the β-lactoglobulin, was investigated by sequencing in 263 lactating Sarda goats in order to assess its association with milk traits. Milk traits included: milk yield, fat, total protein and lactose content, pH, daily fat and protein yield (DFPY), freezing point, milk energy, somatic cell count, total microbial mesophilic count, rennet coagulation time (RCT), curd firming rate (k20) and curd firmness (a30). A total of 7 polymorphic sites were detected and the sequence analysed was given accession number KM817769. Only three SNPs (c.−381C>T, c.−323C>T and c.*420C>A) had minor allele frequency higher than 0·05. The effects of farm, stage of lactation and the interaction farm × stage of lactation significantly influenced all the milk traits (P < 0·01, P < 0·001) except for lactose content and SCS, which were not affected by the farm, and RCT and k20, which were not affected by the stage of lactation. The BLG gene polymorphism influenced milk yield and DFPY, in relation to SNPs c.−381C>T and c.*420C>A (P < 0·01 and P < 0·05). All three SNPs affected milk pH, and this association was highly significant at c.−381C>T (P < 0·001). The c.−381TT homozygous goats showed lower pH, RCT and k20 than c.−381CT (P < 0·05). In conclusion the polymorphism of the goat BLG gene did not affect the total protein content of the Sarda goat milk, and only weakly influenced RCT and k20. On the other hand, an interesting effect on milk yields and DFPY emerged in two SNPs. This information might be useful in dairy goat breeding programs.

The 5′ flanking region and 3′ UTR of the caprine LALBA gene were analysed by SSCP and sequencing. A total of nine SNPs were detected: three in the promoter region, two were synonymous coding SNPs at exon-1, and four SNPs were in exon-4, within the 3′UTR. The nucleotide changes located in the promoter region (c.−358T>C, c.−163G>A, c.−121T>G) were genotyped by SSCP in 263 Sarda goats to evaluate their possible effect on milk yield, composition and renneting properties. We observed an effect of the three SNPs on milk yield and lactose content. Genotypes TT and CT at c.−358T>C (P < 0·001) and genotypes AG and GG at c.−163G>A (P < 0·01) were characterised by higher lactose contents, while c.−358CC and c.−163AA showed the lower milk yield (P < 0·01). SNPs c.−358T>C and c.−121T>G were part of transcription factors binding sites, potentially involved in modulating the LALBA gene expression. The LALBA genotype affected renneting properties (P < 0·001), as heterozygotes c.−358CT and c.−163GA were characterised by delayed rennet coagulation time and curd firming time and the lowest value of curd firmness. The present investigation increases the panel of SNPs and adds new information about the effects of the caprine LALBA gene polymorphism.