heritability of performance test traits in chianina, marchigiana and romagnola breeds

Performance testing is the main method of selection used for Marchigiana, Chianina and Romagnola breed since 1985. The young bulls are tested in a common central station for 6 months period, starting from the age of about 6 months. The bull selection is carried out accounting for genetic indexes of average daily gain (ADG) measured till weaning (PAGD), ADG realized during the test (TADG) and fleshiness (FLESH) measured at the end of test. Data of 2422 young bulls (735 Marchigiana, 863 Chianina and 824 Romagnola) were used to update estimates of heritability for performance test traits of aforementioned Italian beef cattle breeds. For traits measured till weaning (PADG), heritability differed among breeds from very low values for Marchigiana (0.02) to moderate for Romagnola (0.20), while for TADG, h2 estimates were more similar among breeds, ranging from 0.28 to 0.34. Similarly, h2 values obtained for FLESH trait were higher than values obtained till to weaning, but more variable among breed than TADG, i.e. from 0.19 to 0.55.