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Breeding practices and trait preferences are key to defining sound breeding objectives and designing genetic improvement programs at community level. The current study identifies these factors for village goats within a pilot community-based breeding program in Pella village, North West province, South Africa. Thirty-five farmers were interviewed using semi-structured questionnaire survey to characterize goat farmers’ production system. Breeding objectives were identified in 26 households using own flock ranking experiment and the body weight (kg) and linear measurements (cm) were collected for 10 best does and bucks. Majority of famers were males (83%) and literate (85.7%). Fifteen (43%) farmers owned a buck, and those that did not, relied on communal bucks. Average flock per household was 21±19. Farmer selling price for does was R1588.68±313.17 and bucks were sold for R1663.89±861.91. Body size traits were ranked high for both bucks (0.22) and does (0.10), followed by growth rate of 0.10 does and 0.08 for bucks. Average live body weight for all goats was 38±12 kg. Except for rump length, all linear body measurements studied were significantly correlated with body weight (p

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. Data consisted of tick counts or scores assessing the number of female ticks at least 4.5 mm length and derived from seven populations, with breed, country, number of records and genotyped/phenotyped animals being respectively: Angus (AN), Brazil, 2,263, 921/1,156, Hereford (HH), Brazil, 6,615, 1,910/2,802, Brangus (BN), Brazil, 2,441, 851/851, Braford (BO), Brazil, 9,523, 3,062/4,095, Tropical Composite (TC), Australia, 229, 229/229, Brahman (BR), Australia, 675, 675/675, and Nguni (NG), South Africa, 490, 490/490. All populations were genotyped using medium density Illumina SNP BeadChips and imputed to a common high-density panel of 332,468 markers. The mean linkage disequilibrium (LD) between adjacent SNPs varied from 0.24 to 0.37 across populations and so was sufficient to allow genomic breeding values (GEBV) prediction. Correlations of LD phase between breeds were higher between composites and their founder breeds (0.81 to 0.95) and lower between NG and the other breeds (0.27 and 0.35). There was wide range of estimated heritability (0.05 and 0.42) and genetic correlation (-0.01 and 0.87) for tick resistance across the studied populations, with the largest genetic correlation observed between BN and BO. Predictive ability was improved under the old-young validation for three of the seven populations using a multi-trait approach compared to a single trait within-population prediction, while whole and partial data GEBV correlations increased in all cases, with relative improvements ranging from 3% for BO to 64% for TC. Moreover, the multi-trait analysiswas useful to correct typical over-dispersion of the GEBV. Results from this study indicate that a joint genomic evaluation of AN, HH, BN, BO and BR can be readily implemented to improve tick resistance of these populations using selection on GEBV. For NG and TC additional phenotyping will be required to obtain accurate GEBV. Keywords: beef cattle, genomic selection, ticks, tropical adaptation, host resistance Made available in DSpace on 2021-07-02T15:02:52Z (GMT). No. of bitstreams: 1 Cardoso-FF-et-al-2021-Front.-Immunol.-12-620847.pdf: 956049 bytes, checksum: 8df4623128a231a788ce5792a5cc5c54 (MD5) Previous issue date: 2021

Understanding the biological mechanisms underlying tick resistance in cattle holds the potential to facilitate genetic improvement through selective breeding. Genome wide association studies (GWAS) are popular in research on unraveling genetic determinants underlying complex traits such as tick resistance. To date, various studies have been published on single nucleotide polymorphisms (SNPs) associated with tick resistance in cattle. The discovery of SNPs related to tick resistance has led to the mapping of associated candidate genes. Despite the success of these studies, information on genetic determinants associated with tick resistance in cattle is still limited. This warrants the need for more studies to be conducted. In Africa, the cost of genotyping is still relatively expensive; thus, conducting GWAS is a challenge, as the minimum number of animals recommended cannot be genotyped. These population size and genotype cost challenges may be overcome through the establishment of collaborations. Thus, the current review discusses GWAS as a tool to uncover SNPs associated with tick resistance, by focusing on the study design, association analysis, factors influencing the success of GWAS, and the progress on cattle tick resistance studies.