caa a22 4500 386321086 CHVBK 20180307111627.0 cr unu---uuuuu 161130e198804 xx s 000 0 eng 10.1017/S0003356100042331 doi S0003356100042331 pii (NATIONALLICENCE)cambridge-10.1017/S0003356100042331 Index selection for improved growth and carcass characteristics in a population of Large White pigs [Elektronische Daten] An experiment was carried out over 11 years to investigate selection for economy of production and carcass lean content under ad libitum feeding in Large White pigs. Two lines, a selection (S) and a control (C) line, were involved in the study. The S line comprised 80 females and 10 males and was based at two centres. Boars were performance tested centrally at one of the centres and gilts were on-farm tested. Testing was carried out in groups of two or three full-sibs over the live-weight range 27 o t 87 kg. Selection was based on an index (I) incorporating individual daily live-weight gain (DLWG) and ultrasonically measured backfat thickness (USBF) and a group food conversion ratio (FCR) and generations were overlapping. The C line (32 females and 16 males) was maintained at one centre and males were performance tested alongside S boars to monitor genetic progress. Cumulative realized selection differentials over years 1 to 10 were equivalent to 5·5, 51, 7·0 and 9·4 phenotypic standard deviations for DLWG, USBF, FCR and I respectively and generation intervals averaged 17·0 months. There was little genetic change in DLWG, however, USBF, FCR and I showed substantial improvements with cumulative responses in year 11 of —12·3 mm, —0·22 kg/kg and +45·2 points respectively. The reduction in USBF occurred in the first half of the study with no further improvements being achieved after year 6. This study illustrates the effectiveness of index selection for a limited number of economically important traits but highlights limitations to this approach. Copyright © British Society of Animal Science 1988 Ellis M. Faculty of Agriculture, The University, Newcastle upon Tyne NE1 7RU Chadwick J. P. Faculty of Agriculture, The University, Newcastle upon Tyne NE1 7RU Smith W. C. Faculty of Agriculture, The University, Newcastle upon Tyne NE1 7RU Laird R. West of Scotland Agricultural College, Auchincruive, Ayr KA6 5HW Animal Production Cambridge University Press 46/2(1988-04), 265-275 0003-3561 46:2<265 1988 46 ASC https://doi.org/10.1017/S0003356100042331 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0003356100042331 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ellis M. Faculty of Agriculture, The University, Newcastle upon Tyne NE1 7RU NATIONALLICENCE 700 1- Chadwick J. P. Faculty of Agriculture, The University, Newcastle upon Tyne NE1 7RU NATIONALLICENCE 700 1- Smith W. C. Faculty of Agriculture, The University, Newcastle upon Tyne NE1 7RU NATIONALLICENCE 700 1- Laird R. West of Scotland Agricultural College, Auchincruive, Ayr KA6 5HW NATIONALLICENCE 773 0- Animal Production Cambridge University Press 46/2(1988-04), 265-275 0003-3561 46:2<265 1988 46 ASC CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge