Correlated responses in sow appetite, residual feed intake, body composition, and reproduction after divergent selection for residual feed intake in the growing pig

Residual feed intake (RFI) has been explored as an alternative selection criterion to feed conversion ratio to capture the fraction of feed intake not explained by expected production and maintenance requirements. Selection experiments have found that low RFI in the growing pig is genetically correlated with reduced fatness and feed intake. Selection for feed conversion ratio also reduces sow appetite and fatness, which, together with increased prolificacy, has been seen as a hindrance for sow lifetime performance. The aims of our study were to derive equations for sow RFI during lactation (SRFI) and to evaluate the effect of selection for RFI during growth on sow traits during lactation. Data were obtained on 2 divergent lines selected for 7 generations for low and high RFI during growth in purebred Large Whites. The RFI was measured on candidates for selection (1,065 pigs), and sow performance data were available for 480 sows having from 1 to 3 parities (1,071 parities). Traits measured were sow daily feed intake (SDFI); sow BW and body composition before farrowing and at weaning (28.4 ± 1.7d); number of piglets born total, born alive, and surviving at weaning; and litter weight, average piglet BW, and within-litter SD of piglet BW at birth, 21 d of age (when creep feeding was available), and weaning. Sow RFI was defined as the difference between observed SDFI and SDFI predicted for sow maintenance and production. Daily production requirements were quantified by litter size and daily litter BW gain as well as daily changes in sow body reserves. The SRFI represented 24% of the phenotypic variability of SDFI. Heritability estimates for RFI and SRFI were both 0.14. The genetic correlation between RFI and SRFI was 0.29 ± 0.23. Genetic correlations of RFI with sow traits were low to moderate, consistent with responses to selection; selection for low RFI during growth reduced SDFI and increased number of piglets and litter growth, but also increased mobilization of body reserves. No effect on rebreeding performance was found. Metabolic changes previously observed during growth in response to selection might explain part of the better efficiency of the low-RFI sows, decreasing basal metabolism and favoring rapid allocation of resources to lactation. We propose to consider SRFI as an alternative to SDFI to select for efficient sows with reduced input demands during lactation

Correlated Responses in Sow Feed Intake, Body Composition and Reproduction after Divergent Selection for Residual Feed Intake in the Growing Pig

Residual feed intake (RFI) represents the fraction of total feed intake which is not "explained" by maintenance and production requirements. Selection against RFI was suggested as a tool for increasing feed efficiency while having no correlated change in production traits (Kennedy et al. 1993). A divergent selection experiment on RFI is currently being carried out in the Large White breed; six generations of selection have been completed. Previous studies in mice and cattle (Hugues and Pitchford 2004; Meyer et al. 2008) found low to moderate correlations of RFI in growing animals with traits recorded in mature females. Moreover, the ability of sows selected for higher lean meat growth to sufficiently provide nutrients to piglets during lactation has been questioned. This study was performed to estimate genetic parameters and correlated responses for feed intake, body composition and reproduction traits of sows in lines selected divergently for RFI during growth

Observations préliminaires sur le jambon déstructuré. Description du phénomène et étude de quelques facteurs de variation

National audienc

The SPASIBA Force Field for Studying Iron-Tannins Interactions : Application to Fe3+ /Fe2+ Catechol Complexe

The SPASIBA force field parameters have been obtained for Fe3+ /Fe2+ -Oxygeninteractions occuring between non-heminic iron and hydroxyl groups of polyphenols foundin tannins. These parameters were derived from normal modes analyses based on quantumchemical calculations using the Density Functional Theory (DFT). Four models involvingcomplexation of iron with water ([Fe(H2O)6]3+ , [Fe(H2O)6]2+ ) and with cathechol molecules([Fe(cat)2(H2O)2]-1, [Fe(cat)2(H2O)2]-2) were studied using the Density Functional Theoryand the B3LYP hybrid functional under high spin states of iron