Resumo:
The age at first calving (AFC) has great economic impact on the beef cattle system, and
a calving at 24 months is an objective of selection. However, an AFC around 36 months has
been observed for Nellore cattle. Thus, a genome-wide association study (GWAS) was carried
out with 8,376 records of AFC in Nellore cows. 3,239 animals were also genotyped for the
GGP-Indicus 35K, which has been developed specifically for Bos indicus. The WssGBLUP
method was used, with adjacent SNPs in genomic windows of 1.0 Mb. After cleaning of dataset,
3,218 (2,161 males and 1,078 females) animals genotyped for 30,519 SNPs were used in
GWAS analysis. The average and standard deviation of AFC were 1041.7 and 140.6 days,
respectively. Estimate heritability of AFC was 0.0948±0.0203. The GWAS analysis found 12
genomic regions in BTA1, 2, 4, 5, 8, 10, 12, 15, 18, 19, 21 and 24, which explained a total of
15.84% of the additive genetic variance of IPP. A total of 90 protein coding genes were
identified and the genes HSD17B2, SERPINA14, SERPINA1, SERPINA5, SERPINA6, STAT1,
STAT4, NFATC1, ATP9B, CTDP1, THPO, ECE2, PSMD2, EPHB3, EIF4G1, EIF2B2, DVL3,
POLR2H, MAGEF1, CAMK2N2, TMTC2, GPC6, PRR5L, LDLRAD3, COMMD9, LDLRAD3,
HSD17B3, CACNA2D1, PCLO, ACACA, TADA2A, and LHX1 are related with fertility or
growth, which make them candidates for association studies with AFC.
