Genetic parameters for haemoglobin levels in pigs and iron content in pork

Genetic parameters were obtained for iron content in m. longissimus dorsi (2255 records) and haemoglobin levels recorded at 5 (4974 records) and 21 (2405 records) weeks of age in two sire lines from September 2009 until January 2011. The measure of iron in pork was the mean of two replicates. Genetic associations of haematological traits with meat quality traits (2255 records), as well as growth rate and backfat (close to 60 000 records), were estimated. Analyses were based on an animal model using residual maximum likelihood procedures. Iron content in pork was moderately heritable (0.34 +/- 0.07) and genetic correlations with haemoglobin measures ranged from 0.39 +/- 0.24 to 0.58 +/- 0.13, indicating their potential use as selection criteria for increasing iron levels in pork. However, heritabilities for haemoglobin levels were low, ranging from 0.04 +/- 0.2 to 0.18 +/- 0.04. Procedures to measure haemoglobin on farm may require refinement. Redness of pork, quantified by a* value, had high genetic correlations with iron content (0.90 +/- 0.04 to 0.94 +/- 0.03) and moderate genetic correlations with haemoglobin levels (0.31 +/- 0.22 to 0.55 +/- 0.15). Iron content had significant genetic associations with L* measures (-0.61 +/- 0.14 to -0.54 +/- 0.23), b* value (0.60 +/- 0.14 for dorsal b* measure, 0.50 +/- 0.15 for average of dorsal and ventral b* measures) and pH at 45 min post mortem (-0.42 +/- 0.14). These high genetic correlations between colour measurements and iron content in pork provide further avenues for selection strategies to improve iron content in pork. Current selection practices are not expected to affect iron content in pork, as no significant genetic correlations between performance and haematological traits were found.