Abstract: In this paper, PCR-RFLP technique was firstly adopted to analyze the association of polymorphisms of CSN3, CSN1S2 and beta-lactoglobulin genes with litter sizes of 69 Xinong Saanen dairy goats. The results revealed that there was a statistical significant relationship between CSN3-TaqI locus and litter sizes (P < 0.05). For example, the first birth litter size of individuals with genotype TC were more than those of individuals with genotype CC (P < 0.01), while the second birth litter size of individuals with genotype CC were more than those of individuals with genotype TC (P < 0.05). Moreover, the results showed that no statistical significant difference between CSN3-HindIII locus and litter sizes was found (P > 0.05). However, there was significant relationship between CSN1S2-Alw26I locus and litter sizes. For instance, the first birth litter sizes of individuals with genotype NF more than those of genotype NN (P < 0.05), while the fourth birth litter sizes of individuals with genotype NF was less than those of genotype NN (P < 0.01). No significant correlation between beta-lactoglobulin gene and litter sizes was observed in this experiment. Based on these results, it was indicated that CSN3 and CSN1S2 gene had significant positive effects on litter sizes of dairy goats. So it is primitively presumed that casein gene such as CSN3, CSN1S2 gene and FecB gene probably might be linked, which would well explain the gene effects of CSN3 and CSN1S2 gene on litter sizes. Additionally，CSN3 and CSN1S2 gene can be regarded as effective molecular markers on MAS program for litter size of dairy goat.

Key words: CSN3 gene, CSN1S2 gene, β-lactoglobulin gene, Xinong Saanen Dairy goat, Litter sizes, Correlation