Economic considerations of breeding for polledness versus disbudding in beef cattle.

The domestication of animals has rendered horns less necessary for survival. Moreover, the use of polled and disbudded animals is interesting in order to avoid injuries of animals and handlers, among other advantages. We therefore conducted a comparative economic analysis of different traditional disbudding techniques versus selective breeding for polledness in Nelore cattle, the main beef breed of tropical systems in Brazil. The cost to obtain animals without horns was estimated in three different scenarios: disbudding with hot iron, disbudding with caustic paste, and phenotypic selection for polled animals. Price quotations of the materials were obtained in different states of the country and averaged. An initial frequency of horned animals of 92.16% was obtained based on the records of the Brazilian Association of Zebu Breeders. Selective breeding was found to be the best cost-effective scenario. This result differs from intensive production systems of dairy cattle in which traditional disbudding continues to be the best cost-effective scenario. The main explanation is the lack of difference in the price of Nelore semen from polled and horned bulls. Phenotypic selection for polled animals is the best cost-effective method, and it is in accordance with welfare practices. Care should be taken regarding the intensive use of few polled breeding animals in order to avoid inbreeding depression in other traits.

Associations of FASN gene polymorphisms with economical traits in Nellore cattle (Bos primigenius indicus).

The aim of this study was to identify molecular markers to be applied to marker-assisted selection. Three SNPs of the FASN gene were studied. PCR-RFLP was used for genotyping. The SNPs g.17924A>G, g.17860C>T and g.15603A>G all in the FASN gene were genotyped using the enzymes MscI, DdeI and Hae III, respectively. The animals were raised in extensive systems and belong to three lines selected for growth as part of the Selection Program of Zebu and Caracu Breeds, São Paulo, Brazil. Allele and genotype frequencies were compared between selection lines using the Genepop 3.4. Associations between polymorphisms and the traits studied were evaluated using the PROC MIXED procedure of the SAS/STAT 9.1.3. The G and C alleles were the most frequent alleles of the g.15603A>G and g.17860C>T loci, respectively. The g.17924A>G locus showed no polymorphism in the population studied. Allele and genotype frequencies differed significantly between the NeT line and the NeC and NeS lines. The g.15603A>G polymorphism tended to exert an additive effect on rump fat thickness and male yearling height. For g.17860C>T, an additive effect on male yearling height was observed. Genotype combination analysis revealed a significant effect on loin eye area. Although this study provided evidence of an association between the FASN gene and some traits, more detailed analyses are needed to obtain more efficient molecular markers.