Use of dry-matter intake recorded at multiple time periods during lactation increases the accuracy of genomic prediction for dry-matter intake and residual feed intake in dairy cattle

Context Feed is the largest expense on a dairy farm, therefore improving feed efficiency important. Recording dry-matter intake (DMI) prerequisite for calculating efficiency. Genetic variation of and varies across lactation stages parities. DMI an expensive difficult-to-measure trait. This raises question which time periods during would be most appropriate to measure DMI. Aims The aim was evaluate whether sequence variants selected from genome-wide association studies (GWAS) recorded at multiple parities increase accuracy genomic estimated breeding values (GEBVs) residual (RFI). Methods Data 2274 overseas lactating cows were used GWAS select variants. performed using average phenotypes in 30-day window six different lactation. significant each period either first or later GEBVs RFI Australian BayesRC with 50 k single nucleotide polymorphisms (SNPs) Key results There differences correlations heritabilities between within parity periods. Compared single-nucleotide only, increased by up 11% SNPs plus DMI, lower (by 6%) likely because not RFI. accuracies highest mid- late-lactation parity. Conclusions Our showed that late could capture more genetic prediction through use custom genotype panels selection. Implications Collecting optimal period(s) may help develop accurate cost-effective cattle.