Effect of genetic group and dietary crude protein content on technological properties of thighs intended for dry-cured ham production

This study (supported by AGER, grant n. 2011-0280) investigated the effects of commercial genetic group (GG: Anas, Danbred, Goland and Topigs) and dietary crude protein (CP) content on several technological properties of thighs aimed to dry-cured ham production. Thighs data from 282 pigs from a feeding study that involved 3 batches of 96 pigs each were used. In each batch, pigs were housed in 8 pens balanced for GG and assigned either to conventional (CONV) or low (LP) CP diets providing 147 or 119 g/kg CP and 6.0 or 4.8 g/kg standardized ileal digestible (SID) lysine in early (90 to 120 kg BW) and 132 or 103 g/kg CP and 4.4 or 3.5 g/kg SID lysine, respectively (12 pigs per pen, gilts and barrows, and 4 pens per treatment in each batch). Pigs were slaughtered when BW averaged 166 kg and carcasses were dissected. After a 24 h chilling period, thighs were dressed, subcutaneous fat thickness was measured and a trained operator scored the dressed thighs. A sample of thighs subcutaneous fat was individually collected to determine fatty acid (FA) composition and iodine number. Thighs were seasoned according to S. Daniele procedures and the weight of raw and dry-cured hams was recorded. Data were analysed according to a linear mixed model including the effects of batch, pen, diet, GG and sex and some interactions. The GG influenced the thigh dressed and seasoned weight and seasoning loss % (P<0.001), and affected marbling (P<0.001), fat cover (P<0.001) and lean colour (P=0.001). In particular ANAS, compared to Danbred, produced lighter thighs with a thicker fat cover and reduced seasoning loss. Thighs from Danbred were also more marbled and paler than those from the other GG. Subcutaneous fat of thighs from ANAS was richer in saturated FA than that of Topigs and contained a lower amount of polyunsaturated FA than that of Danbred, resulting in the lowest iodine number. Thighs from pigs fed LP showed higher fat covering thickness and score (P<0.05), a more saturated FA proportion and lower iodine number (P<0.05), and lower seasoning losses than those from CONV fed pigs, but also an increased marbling score. In conclusion, the provision of low CP and SID lysine diets seems not only economically and environmentally convenient, but it may also improve several important technological properties of raw hams. Nevertheless, the ncreased marbling score should be taken into account especially when using GG with high marbling tendency such as Dandred and Topigs.