Studio del polimorfismo del gene dell'ormone della crescita (GH) e sue associazioni con le performances produttive in capre di razza sarda

This research tries to give a contribution to the characterization of the genetic patrimony of the Sarda breed goat; the aim was to assess the degree of sequence polymorphism of the Growth hormone (GH) gene and its possible correlations with milk productive traits. 50 pluriparous lactating goats were analyzed with the PCR-SSCP method, and their productive traits were monitored throughout lactation. Several polymorphic patterns were identified: two, eight, twelve and six within the exons 2, 3, 4 and 5, respectively. DNA sequencing of polymorphic patterns found with the SSCP analysis allowed to explain the observed variability with nucleotide sequence variations. Some mutations found in the exons 2, 3 and 4 of the GH gene cause some predicted aminoacid substitutions in the growth hormone peptide, that may affect the functionality of the mature peptide. The statistical analysis regarding the association between the SSCP polymorphic patterns and milk productive traits suggests an association between some polymorphisms in exons 2, 4 and 5 and daily milk yield; and between some polymorphisms within the exons 2 and 3 and the percentage of fat. The exon 4 showed significant differences between polymorphic patterns related to milk protein percentage and pH. These results underline the importance of GH as a candidate gene to consider in breeding programs, and highlight the high genetic variability at this locus in Sarda breed goats, encouraging further studies in this field.