Iberian pig adaptation to acorn consumption: II. Net portal appearance of amino acids

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.

Net portal appearance of proteinogenic amino acids in Iberian pigs fed betaine and conjugated linoleic acid supplemented diets

“…Overall, NPA of AA in the present study reached a maximum (between 60 and 180 min) and decreased gradually, in agreement with the literature (Lenis et al, 1996;van der Meulen et al, 1997;Agyekum et al, 2016). In a previous study (Lachica et al, 2018a), we reported the maximum peak 30 min postprandial as result of the small amount of feed offered. In the present study the time pattern for essential, non-essential, and total AA was similar.…”

“…Simoes Nunes et al (1991) reported a general increment of AA absorption when pigs fed 0.24 casein were compared to pigs fed 0.12 casein diets. Lachica et al (2018a) reported lower NPA of essential AA when Iberian pigs were fed 0.25 of the daily ration of a diet of much lower content of CP (52 g/kg DM) than in the present study (17 vs. 183 (as average) μmol/min).…”

“…Comparing with previous studies with Iberian pigs (Rodríguez-López et al, 2010, 2013González-Valero et al, 2016;Fernández-Fígares et al, 2018;Lachica et al, 2018aLachica et al, , 2019, PPF (or portal blood flow) was on average greater in the present study as the amount of feed offered during sampling was also greater (1 instead of 0.25 of total daily ration), and comparable with modern breeds under similar experimental conditions (Yen et al, 2004;Hooda et al, 2009). In general, differences observed in the literature could be due to the experimental conditions, so great care is recommended when comparing data (Simoes Nunes and Malmlof, 1992;Ellis et al, 1995).…”

“…Lenis et al (1996) reported that NPA of non-essential AA represented 0.37 of the total in growing barrows fed different amount of fiber at 2.6 × ME for maintenance. On the other hand, NPA of essential AA represented barely 0.07 of total NPA of AA in Iberian growing pigs restrictively fed a very low-protein diet (Lachica et al, 2018a).…”

“…The NPA of AA was defined as the amount of ingested AA appearing in the portal blood as opposed to true absorption, the amount disappearing from the lumen (Rérat et al, 2002). In previous studies (González-Valero et al, 2012;Lachica et al, 2018a) we determined the NPA of AA of pigs fed an amount of feed proportional to the measurement period (0.25 of the daily ration for a 6 h measurement period) simulating extensive management where Iberian pigs spend the whole day grazing to cover their nutritional requirements. However, in the present study the whole daily ration was offered and subsequently NPA of AA measured over a relatively short period of time (6 h) which is more applicable to Iberian pigs reared under an intensive system when pigs are fed once or twice a day.…”