Iberian pig adaptation to acorn consumption: I. Net portal appearance of metabolites

Most valuable cured products from Iberian pigs come from pure bred animals raised for a final grazing-fattening period where pigs eat mainly acorns, a low protein energy rich fruit. This is a nutritional challenge for animals fed equilibrated diets from weaning. The aim of the study was to determine net portal appearance (NPA) of metabolites in gilts fed acorns and evaluate adaptational changes after one week of feeding. Two sampling periods were carried out (after one day and after one week of acorn feeding) with six gilts (34 kg average BW) set up with three catheters: in carotid artery and portal vein for blood sampling, and ileal vein for para-aminohippuric acid (PAH) infusion to measure portal plasma flow (PPF). Pigs were fed at 2.5 × ME for maintenance a standard diet in two portions, at 09:00 (0.25) and 15:00 h (the remaining 0.75). On the day prior to the first sampling period, pigs were fed 2.4 kg of oak acorns. After feeding 0.25 of ration a 6 h serial blood collection was initiated. Following an identical protocol, a second sampling session was performed 1 week later. Adaptation to acorn consumption decreased NPA of ammonia (47%, P < 0.001). Although there was a transfer of urea from the gastrointestinal tract to the circulation in both sampling periods, no differences in NPA of urea was found (P > 0.05). NPA of glucose was not influenced by sampling period (P > 0.05), but NPA of lactate was greatly increased (231%, P < 0.001). There was a negative NPA of albumin although adaptation to acorn feeding did not alter it. Although NPA of triglycerides and cholesterol were unchanged, a subtle increase in arterial and portal cholesterol was noticed (9.6%, P < 0.01). Pigs fed a protein deficient diet for one week adapted decreasing NPA of ammonia for saving metabolic energy as less ammonia would become available for conversion to urea.