Selection for Resistance to Swine Mycoplasmal Pneumonia over Five Generations in Landrace Pigs

Good genetic progress was achieved over five generations for both disease resistance and high meat production, according to new research from Japan.
calendar icon 28 June 2012
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The objective of this experiment, published recently in Livestock Science, was to evaluate the selection of a pig line with improved resistance to swine mycoplasmal pneumonia and meat production in Landrace pigs, according to H. Kadowaki and colleagues at Tohoku University in Japan.

The selection was conducted over five generations using estimated breeding values of daily gain, backfat thickness and mycoplasmal pneumonia scores (MPS).

In order to evaluate various lung lesions, the scientists established two different rearing environments (regularly cleaned versus not cleaned) for the pigs.

The heritability estimates for daily gain, backfat thickness and mycoplasmal pneumonia scores were 0.65, 0.60, and 0.07, respectively.

To compensate for the low heritability of MPS, the researchers examined the genetic correlation of immunity traits with the score to determine their usefulness in a selection index. Cortisol plasma levels at 105kg body weight had a high positive genetic correlation (0.65) with MPS and therefore, they used as an immunity trait.

The average breeding values in the fifth generation, as expressed in standard deviation units, were 1.32 for daily gain, -0.70 for mycoplasmal pneumonia score, and -0.04 for backfat and plasma cortisol level.

The selection traits showed good genetic progress in five generations, demonstrating the possibility of selecting for both disease resistance and high meat production in animals, concluded Kadowaki and colleagues.


Kadowaki H., E. Suzuki, C. Kojima-Shibata, K. Suzuki, T. Okamura, W. Onodera, T. Shibata and H. Kano. 2012. Selection for resistance to swine mycoplasmal pneumonia over 5 generations in Landrace pigs. Livestock Science, 147 (1–3): 20-26.

Further Reading

- You can view the full report (fee payable) by clicking here.

Further Reading

- Find out more information on enzootic/mycoplasmal pneumonia by clicking here.

June 2012
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