Identification of milk protein percentage QTLs in Italian Friesian cattle by selective genotyping two GDD families with AFLP and SSR markers

In this work we evaluated the combined use of AFLP markers and selective genotyping in a Grand Daughter experimental design (GDD), to identify chromosomal regions candidate to contain QTL for milk protein percentage (PP) in Italian Friesian cattle. We verified the approach by microsatellite analysis of 4 candidate chromosomal regions. Twenty-five AFLP primer combinations, assayed on the extreme minus and plus-variant half-sibs and on the grandsires of 2 GDD families, produced 180 polymorphic bands of paternal origin. Association analysis resulted in 16 AFLPs significantly associated to PP-EBVs (Pless than or equal to 0.05), that mapped on 8 chromosomes, in regions where PP-QTLs were identified in previous studies. Microsatellite analysis confirmed association for 2 regions of BTA10 and BTA28