Influence of para-aminohippuric acid analysis on net portal-drained viscera flux of nutrients in pigs.

In nutrition studies, para-aminohippuric acid (PAH) is a marker frequently used to measure blood flow in pigs, which is essential for estimating portal-drained viscera (PDV) flux of nutrients. The aim of this study was to evaluate the PAH analytical method by means of qualimetric statistical procedures to estimate the matrix effect and the accuracy and limits of quantitation of the method. Net PDV flux of nutrients was determined in five multi-catheterized pigs using water, plasma or commercial serum as standard matrix. A proportional systematic error due to matrix effect was found for plasma and serum. Mean recovery was 99.4%, and intra- and inter-day precision of the method was 2.4% and 3.8% relative standard deviation, respectively. The limit of quantification was 0.22 mg PAH/l. Use of water for the PAH standard curves underestimated portal blood flow compared with PAH standards prepared with plasma or commercial serum (706, 954 and 927 ml/min; P<0.05, respectively). Consequently, PDV O2 consumption, glucose and amino acids fluxes were underestimated by 33% (P<0.001). In conclusion, our results stress the importance of using plasma from pigs not infused with PAH or alternatively commercial pig serum to prepare PAH standards to determine blood flow in pigs to avoid underestimation of blood flow.

An estimation of the protein requirements of Iberian x Duroc 50:50 crossbred growing pigs.

The effects of dietary protein content on the rates of gain and protein deposition were studied in Iberian (IB) × Duroc (DU) 50:50 barrows at 2 stages of growth [10.6 ± 0.2 (n = 28) and 60.0 ± 0.4 (n = 24) kg initial BW]. Two feeding, digestibility, and N-balance trials were performed. At each stage of growth, they were allocated in individual pens and given restrictedly (at 0.9 × ad libitum intake) one of 4 pelleted diets of similar energy concentration (13.8 to 14.5 MJ ME/kg DM), formulated to provide 4 different (ideal) CP contents (236, 223, 208, and 184 g CP/kg DM in the first trial, and 204, 180, 143, and 114 g CP/kg DM in the second trial). Feed allowance was offered in 2 daily equal meals. The average concentration of Lys was 6.59 ± 0.13 g /100 g CP for all diets. Whatever the stage of growth, average daily BW gain and gain to feed ratio were unchanged by increases in dietary CP content (477 ± 7 and 1,088 ± 20 g, and 0.475 ± 0.027 and 0.340 ± 0.113, respectively, in the first and second trial). In pigs growing from 10 to 27 kg BW, the average rate of N retention increased linearly (P < 0.01) on increasing the protein content in the diet up to a break point, so a linear-plateau dose response was observed. Pigs fed diets providing 208 to 236 g/kg DM did not differ in rate of protein deposition (PD). A maximum value of 87 (13.93 g N retained × 6.25) g PD/d was obtained when the diet supplied at least 208 g CP/kg DM. The broken-line regression analysis estimated dietary CP requirements at 211 g ideal CP (15.2 g total Lys)/kg DM. In the fattening pigs, there was a quadratic response (P < 0.01) in the rate of N retention as dietary CP content increased. Maximum N retention (18.7 g/d) was estimated from the first derivative of the function that relates the observed N retained (g/d) and dietary CP content (g/kg DM). This maximum value would be obtained by feeding a diet containing 185 g ideal CP (13.3 g total Lys)/kg DM and represents the maximum capacity of the IB × DU 50:50 pigs for protein accretion (i.e., 117 g PD/d). Consequently, cross breeding of IB dams with Duroc sires alters the metabolic response to dietary CP supply by increasing the potential of the crossbred to accrete protein and by modifying the pattern of PD response with BW.

Influence of betaine and conjugated linoleic acid on development of carcass cuts of Iberian pigs growing from 20 to 50 kg body weight.

Twenty Iberian gilts (20 kg body weight, BW) were fed diets containing no betaine or conjugated linoleic acid (CLA) (Control), 0.5% betaine, 1% CLA, or 0.5% betaine+1% CLA. Additionally, 5 pigs were killed at 20 kg BW for the initial points of the allometric equations. At 50 kg BW, left semicarcasses were cut into primal cuts, hams and shoulders trimmed and dissected. CLA alone did not affect any analyzed parameter. Betaine increased (23 and 21%, respectively) the yield of shoulder butt and spine and decreased allometric growth coefficient of belly and backfat, compared to Control diet. Tenderloins and trimmed hams of pigs fed CLA+betaine diet developed later and were heavier (22 and 5%, respectively) than Control pigs. Also, leaf fat developed earlier and had lighter weight (32%). Furthermore, pigs fed CLA+betaine diet had heavier lean (5%) and fat free lean (6%) of shoulders compared to Control pigs.