Heat stress is associated with impaired meat quality and disruption of redox balance. This study investigated the effect of chronic exposure to high temperature on meat quality and antioxidant markers of muscles (longissimus lumborum and gluteus medius) of growing Iberian pigs. Twenty-four pure Iberian pigs were allocated during 28 days to one of three treatments (n = 8/treatment): thermoneutral conditions (20 °C) and ad libitum feeding (TN), heat stress conditions (30 °C) and ad libitum feeding (HS) and thermoneutral and pair-fed with HS (TN-pf). Muscles of the HS group had greater intramuscular fat content than the TN-pf group and higher Zn levels than TN and TN-pf, whereas differences on fatty acid composition were negligible. Heat exposure did not affect pH, color coordinates of redness (a*) and yellowness (b*) and MDA values but had a positive influence on lightness and drip losses. Moreover, chronic heat stress stimulated the activity of antioxidant defenses SOD, CAT and GPx. The statistical factor analysis adequately classified the muscles studied, but was unable to differentiate samples according with treatments. Findings of the present study support an adaptive response of the Iberian pig to high temperatures and show the high Iberian meat quality even under adverse climate situations.

This study analyzes quality traits of longissimus lumborum and gluteus medius in surgically castrated (SC) males, inmunocastrated (IC) males and IC female Iberian pigs reared in intensive conditions (n = 18/sex). Vaccination with Improvac® was applied at 18 and 26 weeks of age and slaughtering at 31 weeks. At such conditions, notable sex differences were found. Both muscles of IC males were less red (P < .01), longissimus had lower intramuscular fat (P < .01) and gluteus less Fe content (P < .01) than SC males and IC females. Loins from IC males also exhibited higher drip losses (2.7% at 24 h) than SC males (1.9%) and IC females (1.6%) (P < .001). Fatty acid composition of muscles differed among sexes, especially polyunsaturated fatty acids, which varied as follows: IC males > IC females > SC males in both muscles. It was concluded that meat quality traits differed between inmunocastrated and surgically castrated male Iberian pigs.

SUMMARY When working with multi-catheterized animals, success and failure are separated by surgical procedures and minor details in catheter design and care. The current paper is a detailed description of novel approaches to multi-catheterization of pigs for investigations into nutrient absorption and metabolism of portal-drained viscera (PDV) in a native obese (Iberian) and a modern (Landrace) breed. Three Iberian and three Landrace gilts (25 kg average body weight; BW) were fitted with catheters in the carotid artery (CA), the portal vein (PV) and the ileal vein (IV). Tygon rings were attached to the catheter to mark the extent of introduction into the vessel and facilitate its fixing by means of a non-absorbable suture. The PV was catheterized through the visceral side of the left-lateral lobe of the liver and IV through a branch of the vein. The CA was secured directly in place with a purse-string suture where the artery was not occluded. Patency of the catheters was checked weekly and catheters filled with sterile heparinized saline and closed by two knots. Portal blood flow was determined to test the procedures. A 15 ml pulse dose of para-aminohippuric acid (PAH; 2% w/v) was infused into IV 45 min prior to blood sampling, followed by continuous infusion of 0·8 ml/min. Blood samples (4·5 ml) were taken simultaneously from CA and PV, using heparinized tubes, 5 min before feeding 0·25 of the total daily ration (barley–soybean meal diet; 160 g crude protein (CP)/kg; 14–14·5 MJ metabolizable energy (ME)/kg dry matter (DM); 2·4×ME for maintenance), and every 30 min for 4 h and then hourly until 6 h after feeding. Blood was centrifuged and plasma harvested and stored at −20 °C until PAH analysis. Whole-blood flow was based on the Fick principle. Post-prandial PDV blood flow was lower for the Iberian pigs than Landrace (866 and 1464 ml/min, respectively). The concurrence of access to the PV through the liver with a minimal wound, the non-occluded blood flow in CA, and the catheter design and care were all critical for the fast recovery of pigs and catheter patency. The procedures followed are recommended for studies of absorption of nutrients from the gastrointestinal tract and the impact of PDV on the metabolism of conscious, unrestrained, growing pigs.

SUMMARY: Improvements of a home-made mobile open-circuit respirometry system for the rapid determination of methane (CH₄) and carbon dioxide (CO₂) production, oxygen (O₂) consumption and, thereafter, heat production (HP) for small ruminants are described and validated. Upgrades consisted of three main features: utilization of a head hood (replacing the previous face mask); use of a computerized control system, data acquisition and recording for gases and air flux (replacing collecting bags for air sampling); and use of a gas cooler to remove the air sample moisture (replacing the chemical drier (silica gel) approach). Calibration factors were established by injecting nitrogen (N₂) and CO₂ in the system into the head hood. Repetitive and consistent values for the calibration factor were obtained for O₂ and CO₂ which confirmed the absence of leaks and the good performance of the system. In addition, an experimental test with 12 Manchega female dry sheep was conducted to validate the system. Three diets based on cereal grain, fibrous by-products and alfalfa hay (ALH) were used with four sheep per diet. Metabolizable energy intake was close to metabolizable energy for maintenance. Average HP measured by indirect calorimetry (respiratory quotient (RQ) method) was close to the average HP determined from Carbon–Nitrogen balance (CN method) accounting for 443 and 426 kJ/kg^0·75 body weight (BW) per day, respectively. Fasting HP was determined by the RQ method with two sheep from the ALH diet accounting for 269 kJ/kg^0·75 BW per day. The head hood and computerized control, data acquisition and recording as well as the gas cooler improved the system by reducing the labour input without loss of functionality for measuring gas exchange and energy metabolism in small ruminants.