Multiple Country and Breed Genomic Prediction of Tick Resistance in Beef Cattle.

Ticks cause substantial production losses for beef and dairy cattle. Cattle resistance to ticks is one of the most important factors affecting tick control, but largely neglected due to the challenge of phenotyping. In this study, we evaluate the pooling of tick resistance phenotyped reference populations from multi-country beef cattle breeds to assess the possibility of improving host resistance through multi-trait genomic selection.

Network analysis uncovers putative genes affecting resistance to tick infestation in Braford cattle skin.

Background: Genetic resistance in cattle is considered a suitable way to control tick burden and its consequent losses for livestock production. Exploring tick-resistant (R) and tick-susceptible (S) hosts, we investigated the genetic mechanisms underlying the variation of Braford resistance to tick infestation. Skin biopsies from four-times-artificially infested R (n = 20) and S (n = 19) hosts, obtained before the first and 24 h after the fourth tick infestation were submitted to RNA-Sequencing.

Linkage disequilibrium, persistence of phase and effective population size estimates in Hereford and Braford cattle.

Background: The existence of moderate to high levels of linkage disequilibrium (LD) between genetic markers and quantitative trait loci (QTL) affecting traits of interest is fundamental for the success of genome-wide association (GWAS) and genomic selection (GS) studies. Knowledge about the extent and the pattern of LD in livestock populations is essential to determine the density of single nucleotide polymorphisms (SNP) required for accurate GWAS and GS. Moreover, observed LD is related to historical effective population sizes (Ne), and can provide insights into the genetic diversity history of populations.

Sex pheromone of the American warble fly, Dermatobia hominis: the role of cuticular hydrocarbons.

Chemical communication between adults of the American warble fly, Dermatobia hominis (Diptera: Oestridae), was investigated by electroantennography and behavioral bioassays. Significant electroantennographic responses were recorded from both sexes to hexane-soluble cuticular lipids from either sex. Olfactometer tests indicated an attraction between males and females, and between females.