Mapeamento de QTLs para características de crescimento e de resistência no cromossomo 14 de bovinos F2 provenientes de um cruzamento Gir x Holandês.
Resumo
Brazil possesses the largest commercial bovine herd in the world and cattle
represents about 43% of agricultural PIB of Brazil. Crossing Bos taurus and Bos
indicus species allows the combination of traits of production from the first specie and
of rusticity from the second specie for the genetic improvement of the bovines. Due
to the economical relevance of livestock in Brazil, the search for regions in the
genome that contribute to prodution traits is object of many studies including traits
such as meat yield, precocity of growth and many weight measures (eg. birth weight,
yearling weight). The endoparasites and ectoparasites have great economical
relevance, once the growth losses and production (meat and milk) affect the bovine
herd and consequently, the producer and consumer. The objective of this work was
to map QTL (Quantitative Trait Loci) for growth traits and for resistance to
ectoparasite and endoparasites through the BTA14 scan, using microssatellite
markers in a F2 population Holstein x Gyr. The QTL mapping for the trait birth weight
(BW) suggested a QTL (P <0.05) at 1 cM from centromere and for the weight at 60
days (P60), a suggestive QTL (P <0.05) was found at 0 cM from centromere. The
mapping for resistance to the ectoparasite Boophilus microplus revealed a significant
QTL (P<0.01) at 22 cM from centromere but no association was observed for
endoparasites. Together, the results found in this work suggest the possibility to map
regions of the bovine genome that affect quantitative traits, like growth and
resistance, by means of microssatellite markers.