Productive performance and in vivo body composition across the growing and finishing period and carcass traits in pigs of four sex types.

This study compares performance, body and carcass composition among castrated (CM), immunocastrated (IM) and entire males (EM), and females (FE) at 30, 70, 100 and 120 kg of body weight (total of n = 92; 20-24/sex type). Overall, IM had similar growth and feed intake to CM and greater than EM and FE. At each slaughter stage, IM had a lower killing-out percentage than CM and FE, in line with their heavier liver and kidneys. Flare fat proportion and backfat thickness on the ham and at the last rib level were similar for IM, EM and FE, and these were lower than CM. In EM and FE, backfat between the 3rd and 4th last ribs was lower and carcass lean content was higher than in CM, whereas IM were intermediate and not different to the other sexes. Females showed the largest ham proportion, this cut being leaner and less fatty than in CM. Belly proportion was higher in CM than in EM.

Evolution of testes characteristics in entire and immunocastrated male pigs from 30 to 120 kg live weight as assessed by computed tomography with perspective on boar taint.

The present study addressed (1) the levels of boar taint compounds in entire (EM) and immunocastrated (IM) male pigs during their growth, (2) the evolution of testes volume and density and (3) the relationship between physical characteristics of the testes and boar taint compounds. For that purpose 24 EM and 20 IM pigs were CT scanned at several body weights (TBW). After each scanning a subsample of pigs was slaughtered, and subcutaneous fat was collected to determine androstenone and skatole concentration. Additional subsample (n=4/sex) was CT scanned 13 days after the second vaccination (V2). Testes density changes with growth, is different in EM and IM, but is not a reliable marker of the level of boar taint compounds. On the other hand, testes to body volume ratio is a better predictor for androstenone and could provide a good tool at slaughter plants to detect immunocastrated pigs with high boar taint compounds.

Estimation of carcass composition and cut composition from computed tomography images of live growing pigs of different genotypes.

The aim of the present work was (1) to study the relationship between cross-sectional computed tomography (CT) images obtained in live growing pigs of different genotypes and dissection measurements and (2) to estimate carcass composition and cut composition from CT measurements. Sixty gilts from three genotypes (Duroc×(Landrace×Large White), Pietrain×(Landrace×Large White), and Landrace×Large White) were CT scanned and slaughtered at 30 kg (n=15), 70 kg (n=15), 100 kg (n=12) or 120 kg (n=18). Carcasses were cut and the four main cuts were dissected. The distribution of density volumes on the Hounsfield scale (HU) were obtained from CT images and classified into fat (HU between -149 and -1), muscle (HU between 0 and 140) or bone (HU between 141 and 1400). Moreover, physical measurements were obtained on an image of the loin and an image of the ham. Four different regression approaches were studied to predict carcass and cut composition: linear regression, quadratic regression and allometric equations using volumes as predictors, and linear regression using volumes and physical measurements as predictors. Results show that measurements from whole animal taken in vivo with CT allow accurate estimation of carcass and cut composition. The prediction accuracy varied across genotypes, BW and variable to be predicted. In general, linear models, allometric models and linear models, which included also physical measurements at the loin and the ham, produced the lowest prediction errors.