Livestock Production Science 67 2001 281–292 www.elsevier.com locate livprodsci
Fat deposition and distribution measured by computer tomography in three genetic groups of pigs
K. Kolstad
˚
Department of Animal Science , Agricultural University of Norway, P.O. Box 5025, N-1432 As, Norway
Received 1 October 1999; received in revised form 23 February 2000; accepted 14 March 2000
Abstract
Amounts and proportions of subcutaneous, inter intra muscular and internal fat depots were quantified by computer tomography CT at 10, 25, 50, 85 and 105 kg live weight in each of 141 animals of the three genetic groups: Norwegian
Landrace, Duroc and a crossbreed between Norwegian Landrace and a line selected for high backfat and slow growth LLP. Selection for reduced fat content at slaughter has resulted in earlier maturation of the fat depots P , 0.05. Differences were
found between genotypes in fat amounts and distribution from 10 to 105 kg live weight. At weaning, piglets of modern breeds do not differ in total fat amounts from ‘old’ type. Subcutaneous fat depot is the largest one, and is relatively largest at
weaning in all three genetic groups. This fat depot is absolutely and relatively largest in LLP P , 0.05. LLP has highest amounts of fat from 50 kg live weight P , 0.01. The efficient, fast growing Landrace breed has relatively high amounts
and proportions of internal fat during the whole growth period. Amounts and proportion of inter intramuscular fat depot appears to be high in the Duroc breed at 85 kg but not earlier.
2001 Elsevier Science B.V. All rights reserved.
Keywords : Pig; Fat amounts; Fat distribution; Breed differences; Computer tomography
1. Introduction pigs differ with respect to fat amounts and fat
distribution Wood and Cameron, 1994; Kolstad et Efficient pig meat production is best obtained with
al., 1996; Schinckel et al., 1996. There is also a combination of fast lean growth and low fat
genetic variation within breeds de Vries and van der ¨
deposition. Efficient production of good quality meat Wal, 1993; Schworer et al., 1999.
may be obtained by reducing the total fat amounts The two fat depots of greatest interest to the
while fat depots important for meat quality is kept at industry so far are backfat and intramuscular fat, also
optimum levels. It is generally known that breeds of known as marbling. Backfat has been the selection
criterion for leanness in several breeding schemes for several decades. Marbling has gained increased
attention during the past few years due to its connection to meat quality DeVol et al., 1988;
Barton-Gade, 1990; Tornberg et al., 1993; Casteels
Tel.: 147-64-948-000; fax: 147-64-947-960. E-mail address
: kari.kolstadihf.nlh.no K. Kolstad.
et al., 1994. Selection for high performance may
0301-6226 01 – see front matter
2001 Elsevier Science B.V. All rights reserved. P I I : S 0 3 0 1 - 6 2 2 6 0 0 0 0 1 9 5 - 0
282 K
. Kolstad Livestock Production Science 67 2001 281 –292
have resulted in a lower marbling score, and poorer lar fat Wood and Cameron, 1994. Also included
meat quality compared to less intensively selected was a crossbreed LLP between Norwegian Land-
breeds Gregor and Scholz, 1993; Cameron et al., race L and a selection line LP selected for high
1999. backfat and low growth rate Vangen, 1979. The LP
Differences between breeds of pig are found in selection line pigs have a backfat thickness of
amounts of internal fat Kolstad et al., 1996. approximately 31 mm at slaughter Vangen, 1980.
Internal fat depots do not influence carcass quality. Comparing amounts and distribution of fat in those
They will, however, influence the efficiency of meat genetic groups may help us to understand the
production. Whole body scanning is necessary to background of genetic variation in these traits, and
detect internal depots in live animals. indicate potentials for genetic changes.
Computer tomography CT can be used for detailed measurement of body components and fat
2.2. Experimental design, housing, feeding and distribution on live animals Afonso, 1992; Vangen
weight recording and Thompson, 1992; Kolstad and Vangen, 1996;
Kolstad et al., 1996. Earlier studies based on CT A total of 141 pigs were included in the experi-
observations on different breeds of pigs by Luiting et ment representing the three genetic groups Landrace
al. 1995, Kolstad and Vangen 1996, and Kolstad 63, Duroc 62 and LandraceLP 16. For the
et al. 1996 proved breed differences in mainte- experiment, two males and two females were select-
nance requirements, fat distribution and fat mobilisa- ed at random from each litter. The experiment
tion in pigs at about 60 kg live weight, i.e. when the included four batches, the first one starting in the
pigs grow most rapidly. The aim of the present study autumn 1996, and the last one ending in the spring
was to examine development of different fat depots 1998. All batches included all three genetic groups
in three genetic groups of pigs by repeated measure- and both sexes except the last batch where LLP was
ments of body composition by CT within animals not represented.
from weaning to slaughter, in order to increase the The animals entered the experiment at weaning 5
understanding of the background of genetic variation weeks of age. The animals stayed in mixed groups
in amounts and distribution of fat in pigs at different of about six during the whole experiment, with free
live weights, and indicate potentials for genetic access to water. The indoor temperature was kept at
changes. about 208C.
From weaning to 25 kg live weight, the animals were group fed. Piglets in the first two batches were
2. Material and methods fed ad libitum, or 80 of ad libitum during this
