Abstract
In Iberian pig outdoor production, pigs are fed equilibrated diets until the final fattening period when grazing pigs consume mainly acorns from oak trees. Acorns are rich in energy but poor in crude protein where lysine is the first limiting amino acid (AA). Net portal appearance (NPA) is very useful to ascertain AA available for liver and peripheral tissues. The aim of this study was to determine NPA of AA in Iberian gilts fed with acorns and to ascertain if there was an effect of acorn feeding over time. 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 a marker infusion to measure portal plasma flow (PPF). Pigs were fed at 2.5 × ME for maintenance a standard diet in two meals, at 09:00 (0.25) and 15:00 h (the remaining 0.75). The day previous to first sampling, pig diet was replaced by 2.4 kg of acorn. A serial blood collection was done at −5 min, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5 and 6 h after feeding 0.25 of total daily acorn ration. Following identical protocol, one week later the second sampling was done. NPA of sum of essential AA (EAA) was poor. Although increased NPA of histidine (P < 0.001), leucine, phenylalanine and valine (0.05 < P < 0.08) was found after one week of acorn consumption, the sum of EAA did not change. Furthermore, fractional absorption (NPA/AA intake) of EAA, non-essential AA (NEAA) and total AA was 97, 44 and 49% lower, respectively, at the beginning of eating acorn than a week later. Supplementation, with some of the EAA and NEAA to Iberian pigs during the grazing period would be beneficial to overcome the increased portal-drained viscera (PDV) utilization of AA observed in the present study.
Highlights
There is a growing interest in semi-extensive and extensive production systems where an efficient use of feed resources constitutes a key factor for sustainability and animal welfare
Ileal digestibility of amino acid (AA) of acorn protein has been measured in Iberian pigs (Nieto et al, 2002a; García-Valverde et al, 2007), no information is available on their net portal appearance (NPA)
In a recent manuscript (Fernández-Fígares et al, 2018a), we have evaluated the NPA of metabolites of Iberian pigs fed acorns and we found out that ammonia decreased after one week of acorn consumption
Summary
There is a growing interest in semi-extensive and extensive production systems where an efficient use of feed resources constitutes a key factor for sustainability and animal welfare. Recommendations derived from modern breeds have been used in Iberian pigs, even though there are evidences that they have distinct metabolic (Fernández-Fígares et al, 2007) and nutritional features (Nieto et al, 2012). Ileal digestibility of AA of acorn protein has been measured in Iberian pigs (Nieto et al, 2002a; García-Valverde et al, 2007), no information is available on their net portal appearance (NPA). In a recent manuscript (Fernández-Fígares et al, 2018a), we have evaluated the NPA of metabolites of Iberian pigs fed acorns and we found out that ammonia decreased after one week of acorn consumption. The aim of the present study was to determine NPA of AA in Iberian pigs fed with acorn from evergreen oak (Quercus ilex rotundifolia) and if there was an adaptation effect to a very low protein diet. The information could be used to establish recommendations of AA supplementation when Iberian pigs are in grazing conditions
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