Eli Gjerlaug-Enger defended her thesis on March 11th 2011

Ane Gro Siri Skjelfjord

Genetic analyses of meat, fat and carcass quality traits measured by rapid methods

Abstract from the thesis - PhD thesis 2011:13

The overall aim of this thesis was to analyse meat and fat quality traits using quantitative genetic methods. This study has demonstrated that it is possible to establish simple laboratory practices and high quality rapid analyses of meat and fat quality traits at a research abattoir. Developed multivariate calibration methods and Near-infrared spectroscopy (NIRS) data were used to predict many of the traits studied, and large-scale recordings provided the basis for the genetic analysis of the meat and fat quality traits. In addition, estimated genetic parameters of body composition traits from large-scale Computed tomography (CT) scan of live boars yielded new information about the growth of various body tissues.

The results show that low labour, large-scale measuring methods can provide high heritabilities for several traits. The meat quality traits: pH in M. gluteus medius, M. gluteus profundus and M. longissimus dorsi and drip loss, meat colour and meat composition traits of M. longissimus dorsi showed heritabilities from 0.12 to 0.50 in Landrace and from 0.22 to 0.62 in Duroc. The fat quality traits: fatty acid composition, fat moisture content, and fat colour in subcutaneous fat showed heritabilities from 0.06 to 0.67 in Landrace and from 0.01 to 0.57 in Duroc. The CT traits: growth of muscle, fat, bone and internal organs showed heritabilities from 0.19 to 0.53 in Landrace and from 0.43 to 0.59 in Duroc. On the basis of the parameters estimated here, breeding for a higher lean meat percentage and lower feed convention ratio is expected to result in deterioration of meat and fat quality traits.

In view of the genetic parameters and size of the heritabilities and genetic correlations, some new traits for meat, fat and carcass quality are recommended in the breeding programme for Norwegian Landrace and Duroc. Among the traits investigated, the traits of greatest importance are NIRS-predicted intramuscular fat, drip loss, a* value in meat and NIRS-predicted moisture and fatty acids composition in subcutaneous fat. The percentage of oleic acid, C18:1n-9, from the NIRS analysis is highly heritable and may improve technological quality, sensory properties and human health. A selection for L* value or reflectance in meat is discouraged due to the undesirable influence of the IMF in the measuring. CT scanning makes it possible to select directly for the growth rate of muscle, fat, bones and internal organs of live boars. Pig meat has many qualities important for human nutrition, and is a good source for essential minerals and nutrients, e.g. heme iron, protein with a good amino acid profile and good fatty acids. This study has demonstrated the possibilities of selecting for some of these component traits.

Published: 09.06.11
Updated: 10.06.11
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