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The study of feeding behavior is of particular interest because it is directly related to efficiency of feeding. The aim of our study was to determine the genetic parameters of the feeding behavioral traits in Duroc boars (n = 766) in relation to the feed efficiency based on the analysis of variation components. Genstar and Shauer feeders were used to collect the behavioral data, including daily feed intake (DFI), total daily time spent in feeder (TPD), number of daily visits to feeder (NVD), average duration of each visit (TPV), feed intake per visit (FPV), and feed intake rate (FR). Genetic and environmental variabilities were determined by the mixed model equation using the REMLF90 program. Multiple regression analyses were used to adjust feed conversion rate (FCR) for the duration of the testing period, initial and final body weight, and average daily gain. The average initial body weight was 35.7 kg and the duration of testing period was 78.1 days. Actual FCR values reached 2.20 kg/kg with a phenotypic variability of 26.3%. Moderate values of heritability coefficients (h2) were observed for TPV (h2=0.168), FCR (h2=0.214), and DFI (h2=0.221) traits. The heritability parameters for FPV and TPD traits were higher and accounted to 0.269 and 0.290, respectively. The highest value of h2 was observed for NVD (0.494). Analyses of genetic correlations revealed several interesting findings. The boars, which more often visited feeding stations, spent more time in feeder (r2=+0.536 for NVD/TPD), herewith duration of each visit and feed intake rate were decreased (r2=–0.593 and –0.760 for NVD/TPV and NVD/FR, respectively). Feed conversion rate was positively correlated with TPD (r2=+0.530) and negatively correlated with FR (r2=–0,772). Our research results will be useful for development of artificial selection programs to select Duroc pigs for increased feeding efficiency. The study was supported by RFBR No19-316–90008.

The cost of fodder is the major part in expenditure in pork industry. In this regard, improving the feed efficiency is the main goal of breeding programs for the most of pig breeds. Residual feed intake (RFI) is an alternative measure for feed efficiency, which is accepted in different livestock species including pigs. RFI is defined as the difference between the observed and predicted feed intake based on average daily gain and (additionally) back fat thickness. Our aim was to find the candidate genes responsible for RFI in Russian Duroc boars. RFI values for individual boars (n = 766) were calculated using linear regression of daily feed intake on metabolic mid-test weight and average daily gain. The SNP genotyping was carried out using Porcine GGP HD BeadChip (GeneSeek/Neogene). After data quality control, performed in PLINK 1.9, 43,199 SNPs were selected for genome-wide association studies (GWAS). The average daily gain in studied boars was 957 g with variation in individual animals from 424 to 1508 g. Feed conversion rates averaged to 2.21 kg/kg with variation from 1.8 to 3.7 kg/kg. GWAS results showed the presence of 48 SNPs, which were significantly (P < 0.00001) associated with RFI, including 15 SNPs on SSC2, 9 SNP – SSC4, 2 SNPs – SSC6, 21 SNPs – SSC9, and 1 SNP – SSC17. A search for genes located within 0.4 Mb window (0.2 Mb down-stream to 0.2 Mb up-stream from identified SNP) revealed several putative candidates. Functional annotation of the obtained candidates showed the presence of genes involved in protein metabolism (ADAMTS2,UIMC1 on SSC2; NTNG1 on SSC4), regulation of glucose and bile acid metabolism (FGFR4 on SSC2), neuronal development (ENC1 on SSC2; NTRK1, MEF2D on SSC4), vitamin D and K pathways (BGLAP on SSC4). The study was funded by the Russian Ministry of Science and Higher Education No.0445-2019-0029.