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This study was conducted to assess the effect of E. Coli lipopolyssacharide challenge (IC) on Nitrogen Balance (NB) in growing pigs (19 kg). Three NB trials were performed in a complete RBD, with six nitrogen levels (NL), two sanitary status (control and IC) and two individual replicates per treatment (6 x 2 x 6). Pigs were intramuscular injected with 30 and 34 μg LPS/kg for two consecutive days. Dietary NL ranged from 1.06 to 4.48 % (dry matter), with lysine being limiting in all diets. NB trials lasted 11 days in which feces and urine were collected at the last four days to determine N intake (NI), N excretion (NEX) and N deposition (ND). Data were analyzed as two-way ANOVA and polynomial contrasts were used. Body weight were unaffected by the factors under study (P >0,05). LPS-challenged pigs had a lower (P< 0,05) feed intake compared with control group (372,98 vs. 417,82). Interaction between NL and IC were observed (P< 0,05) for NI, NEX and ND. NL linearly increased NI, NEX and ND, with different equations for both groups (P< 0,05): ND = 127,86 + 246,95 NL in control group whereas ND = 150,66 + 155,4 in LPS group. LPS-challenged pigs fed the three highest NL exhibited a decrease in NI compared with control group (P< 0,05). From NL2 to NL6, ND was also impaired in LPS-challenged pigs compared with control. Nitrogen excretion was higher in LPS-challenged pigs fed the two highest NL compared with pigs from control group (P< 0,05). In conclusion, LPS challenge impairs nitrogen retention in growing pigs by 37%. These outcomes can be used further for modelling procedures to estimate lysine requirements of pigs in different sanitary status.

This study evaluated the effect of conventional (CONV) and sequential feeding (SEQ) programs with diets varying in amino acid content over the day on body composition in growing-finishing pig. Sixty-eight 25-kg (±2.04) BW barrows were assigned to the following feeding programs: 1) CONV in which pigs received 100% of standardized ileal digestible (SID) AA recommendations for the entire day; 2) SEQ providing 80% SID AA recommendations from 2400 to 1159 h and 120% from 1200 to 2359 h (SEQ80-120); 3) SEQ providing 70% SID AA recommendations from 2400 to 1159 h and 130% from 1200 to 2359 h (SEQ70-130); and 4) SEQ providing 60% SID AA recommendations from 2400 to 1159 h and 140% from 1200 to 2359 h (SEQ60-140). The experimental period lasted 82 days. At days 0, 28, 54 and 82 body lean mass, fat and minerals were measured using a dual energy X-ray absorptiometry (DXA). Pigs fed SEQ80-120 had body composition variables similar to CONV pigs (P >0.05). Whereas, pigs fed SEQ70-130 had greater (P< 0.05) body fat mass (5.27 vs 4.48 kg), bone mineral content (0.656 vs 0.605 kg), fat mass gain (0.100 vs 0.073 kg/d) and bone mineral gain (6.92 vs 5.16 g/d) than CONV pigs during phase 1. Still during phase 1, SEQ60-140 fed pigs had greater (P< 0.05) bone mineral content (0.655 vs 0.605 kg), lean mass gain (0.436 vs 0.374 kg/d) and bone mineral gain (7.48 vs 5.16 g/d) than CONV pigs. During phase 3, bone mineral content was higher (P< 0.05) for SEQ70-130 than CONV (1.408 vs 1.269 kg). During the entire experimental period, body composition variables were not affected by SEQ (P >0.05). According to our results, sequential feeding program improves body composition of pigs at the beginning of the growth period.

This study evaluated the effect of conventional and sequential feeding programs with diets varying in amino acid content over the day on nutrient balance for growing-finishing pig. Sixty-eight barrows with an average initial BW of 25.0±2.04 were housed in a single pen with five automatic intelligent precision feeders (AIPF; University of Lleida, Lleida, Spain). Pigs were distributed in four feeding programs: 1) conventional feeding (CONV) in which pigs received 100% of SID AA recommendations for the entire day; 2) sequential feeding (SEQ80-120) providing 80% SID AA recommendations from 0000 to 1159h and 120% from 1200 to 2359h; 3) sequential feeding (SEQ70-130) providing 70% SID AA recommendations from 0000 to 1159h and 130% from 1200 to 2359h; and 4) sequential feeding (SEQ60-140) providing 60% SID AA recommendations from 0000 to 1159h and 140% from 1200 to 2359h. Body lean mass and mineral body content were obtained by DXA analysis and were converted to body protein and P content. Three contrasts were constructed to evaluate the effects between CONV and sequential treatments. In phase 1 (0–28d), pigs fed SEQ70-130 presented higher crude protein intake, N retention, N excretion, P intake and P retention (P < 0.05) compared to CONV fed pigs. SEQ 60–140 fed pigs presented higher P retention and P retention efficiency (P < 0.05) compared to CONV fed pigs. In phase 2 (29–54d), no statistical difference for any evaluated variable was verified (P > 0.05). In phase 3 (55–82d), SEQ70-130 fed pigs showed higher N excretion and lower N retention efficiency and lysine efficiency (P < 0.05) when compared to CONV fed pigs. In the entire experimental period (0–82d), there were no significant differences between treatments. According to our results, sequential feeding program improves nutrient balance of pigs at the beginning of the growth period.

Two nitrogen (N) balance studies were conducted to compare the relative bioavailability (RBV) of L-Met with DL-Met as Met sources in young pigs. In each experiment, 42 barrows (PIC; initial BW in Exp. 1: 10.7 kg and Exp. 2: 20.5 kg) were allotted to 7 experimental diets with 6 pigs per treatment. The basal diets (diet 1) were formulated based on corn and soybean meal being deficient in Met, but adequate for the other AA (Exp. 1: 0.24% standardized ileal digestible [SID] Met; 0.53% SID Met + Cys; 1.30% SID Lys; Exp 2: 0.23% SID Met; 0.47% SID Met + Cys; 1.15% SID Lys). Three graded levels of DL-Met and L-Met (0.03, 0.06 and 0.09%) were supplemented to the basal diet on top to create diets 2 to 7 for both studies. In Exp.1, N retention (% of N absorbed) increased linearly (P < 0.05) with supplementation with both Met sources. The slope-ratio regression estimated the RBV of 106% [95% confidence interval (CI): 39 to 173%] for N retention (% of absorbed) on an equi-molar basis. In Exp. 2, N retained (g/d), N retention (% of N intake and % of N absorbed) increased linearly (P < 0.05) by supplementing with both Met sources. There was no effect of Met sources on all N balance parameters in both studies. The slope-ratio estimated the RBV of 89% (95% CI: -28 to 206%) for N retained (g/d), 95% (95% CI: 13 to 177%) for N retention (% of N intake) and 94% (95% CI: 20 to 167%) for N retention (% of N absorbed), respectively on an equi-molar basis. In conclusion, the 95% CI for the RBV of L-Met covers 100%, indicating the RBV of L-Met is not different from that of DL-Met as a Met source for weaned and growing pigs.