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Carcass and ham quality characteristics of pig populations divided by harvest weights--HW (130 and 160 kg) were evaluated to determine the effects of gender (barrows and gilts) and distinct genetic groups--purebred (DUDU) and crossbred Duroc (DULA, DUWI and DULL) as well as purebred Large White (WIWI) on the suitability for use in dry-cured ham production. At 130kg, DUDU pigs yielded the highest fat thickness of the ham (P<0.01) and an intramuscular fat content (IMF) of 3.15% in Semimembranosus muscle (SM). DUDU pigs also had a SM pH(u) of 5.7. This genetic group met the specifications for dry-cured ham production. No differences could be found in meat quality characteristics between genetic groups harvested at 160 kg. However at this HW, gilts produced significantly (P<0.05) heavier and leaner hams compared to barrows.

Heavy weight gilts commonly show signs of oestrus during the late finishing phase, which results in a period of reduced feed intake and growth rate. Immunization against gonadotropin-releasing hormone (GnRH) (IM, immunocastration) was developed for finishing boars and recently extrapolated to females. Immunocastration acts by suppressing reproductive activity and improving the growth potential. The objective of this study was to evaluate the effects of IM on growth performance, reproductive activity and carcass characteristics of late finishing gilts. Seventy-two gilts (63.49 ± 0.39 kg) were either injected with saline (Intact) or immunized against GnRH (Immunized). The study consisted of three experimental periods: between the first to second immunization (V1 to V2, 15 to 19 weeks of age), from the second immunization to the beginning of daily boar exposure (DBE) (V2 to DBE, 19 to 21 weeks of age) and from the beginning of DBE to slaughter (S) (DBE to S, 21 to 25 weeks of age). Immunized gilts showed an overall increase (from 15 to 25 weeks) of 3.90 kg (P &lt; 0.05) of live weight, 56 g (P &lt; 0.05) of average daily gain (ADG) and 250 g (P &lt; 0.001) of average daily feed intake (ADFI). Immunized gilts had a greater ADFI (+240 g, P &lt; 0.05) and worse feed conversion ratio (+0.26, P &lt; 0.05) from 19 (V2) to 21 weeks of age (before DBE). Furthermore, those females had higher feed intake (+410 g; P &lt; 0.001) plus greater daily weight gain (+92 g; P &lt; 0.05) from V2 to S, and from DBE to S (+470 g of ADFI, P &lt; 0.001; +129 g of ADG, P &lt; 0.01, respectively). Immunocastration had no effect on backfat thickness, lean meat percentage and weight, cold carcass yield or loin depth (P &gt; 0.05). Immunized gilts showed 4.4% increased cold carcass weight (P &lt; 0.01) and 10.6% greater gross flank weight (P &lt; 0.001). Immunization against GnRH did not influence shoulder, collar, loin, belly or ham weights. Nor did it influence belly fat thickness, or meat, skin plus fat and bones yields of cold ham (P &gt; 0.05). Immunocastration reduced ovarian and uterine weights by 82% (P &lt; 0.001) and 93% (P &lt; 0.001), respectively, and suppressed oestrus manifestation in all gilts in the immunized group (P &lt; 0.001). These results indicate that immunization against GnRH is a promising tool for stimulating growth performance with no detrimental effects on carcass quality of heavy weight finishing gilts, by means of oestrus suppression.

a b s t r a c tRecords of a pig population used for dry-cured ham production were used to evaluate genetic groups by multivariate analysis. The investigated genetic groups were as follows: DULL¼Duroc  (Landrace  Large White), DULA¼ Duroc  Landrace, DUWI¼ Duroc  Large White, WIWI¼ Large White and DUDU¼ Duroc. Two groups were obtained for the carcass traits hot carcass weight (HCW), backfat thickness (BT) and loin depth (LD), with the groups including 597 and 341 animals harvested at 130 kg and at 160 kg weights, respectively. Two groups were also found for ham traits gross ham weight (GHW), trimmed ham weight (THW), ham inner layer fat thickness (HIFT), ham outer layer fat thickness (HOFT), pH (PH), and Göfo value, with 393 and 91 animals harvested at 130 kg and 160 kg weights, respectively. The analysis was performed within each group of traits and harvest weights, and the animals without records were excluded. The first and the second canonical variables explained 97.5% and 93.6% of the total variation for the carcass traits at 130 kg and 160 kg, respectively, and 88.8% of ham traits at 130 kg. In the dispersion graph concerning the canonical means, a significant distance was observed between the genetic groups DUDU and WIWI for the carcass traits at 130 kg and 160 kg and the ham traits at 130 kg. The 50% Duroc animals exhibited little dispersion regarding the carcass traits at 130 kg and 160 kg and were not divergent from the DUDU genetic group for the ham traits at 130 kg. In a cluster analysis using the single linkage method, DULL, DULA and DUWI were grouped with a high similarity level for the carcass traits at 130 kg and 160 kg and ham traits at 130 kg. Using the Tocher optimization method, 50% Duroc crossbred and 100% Duroc purebred animals were grouped for the ham traits at 130 kg, suggesting that for ham traits, 50% Duroc animals were similar to 100% Duroc purebred animals. In this context, the genetic groups Duroc  Large White, Duroc  Landrace and Duroc  (Landrace  Large White) are recommended for use in producing dry-cured ham.

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