Effect of the essential amino acid-nitrogen to total nitrogen ratio on lysine requirement for nitrogen retention in growing pigs

Low protein diets supplemented with essential amino acids (EAA) fed to pigs reduce the excess supply of EAA and nitrogen (N). However, low protein diets may become limiting in non-essential amino acids (NEAA) and N, thus affecting the utilization of EAA for N retention. It has been suggested that the EAA-N:total N (E:T) ratio can give an indication of dietary N sufficiency. An N-balance study was conducted to determine the effect of E:T ratio on the Lys requirement for maximum N retention. A total of 80 growing barrows (19.3 ± 0.21 kg initial body weight) were randomly assigned to 1 of 10 diets (n = 8) in 8 blocks in a 2 × 5 factorial arrangement. Diets consisted of a low ratio (LR; E:T of 0.33) or a high ratio (HR; E:T of 0.36) with graded Lys content (0.82%, 0.92%, 1.02%, 1.12%, and 1.22% standardized ileal digestible [SID]). After a 7-d adaptation, a 4-d N-balance collection was conducted. Blood samples were obtained on d 2 of the collection period 2 h after the morning meal for plasma urea N (PUN) analysis. Data were analyzed using the MIXED model procedure with fixed effects of ratio (n = 2), Lys (n = 5), and their interactions. The experimental block (room) was included as a random effect (n = 8). The SID Lys requirement was estimated using PROC NLIN linear broken-line breakpoint model. There was a significant interaction between E:T ratio and Lys (P < 0.01), where LR diets had a higher N retention than HR diets, while increasing Lys linearly increased N retention (P = 0.01) in both HR and LR diets. The marginal efficiency of utilizing SID Lys (P < 0.01) reduced with increasing Lys content, while the efficiency of utilizing N (P < 0.05) increased as Lys increased. The SID Lys required to maximize N retention of pigs fed HR diets was estimated at 1.08% (R2 = 0.61) and LR diets at 1.21% (R2 = 0.80). The current results indicate that N may be limiting in diets with a high E:T ratio, limiting N retention. Supplying additional dietary N, as intact protein, can increase N retention, resulting in a greater Lys requirement.

Optimal dietary standardized ileal digestible lysine and crude protein concentration for growth and carcass performance in finishing pigs weighing greater than 100 kg1,2

Three experiments were conducted to determine the optimal dietary standardized ileal digestible (SID) lysine and CP concentrations for finishing pigs over 100 kg BW. In Exp. 1, 253 pigs (DNA 600 × 241, initially 102.0 kg) were used in a 23-d trial with 7 to 8 pigs per pen and 8 pens per treatment. Dietary treatments contained 4 SID lysine concentrations (0.45, 0.55, 0.65, or 0.75%). To formulate the experimental diets, a corn-soybean meal diet with 0.45% SID lysine was formulated without L-lysine HCl. Then, a corn-soybean meal diet containing 0.75% SID lysine was formulated including 0.23% L-lysine HCl. The 0.45 and 0.75% SID lysine diets were blended to provide the 0.55 and 0.65% SID lysine diets. Increasing SID lysine increased (quadratic, P < 0.05) ADG and ADFI with pigs fed 0.55% SID lysine having the greatest final BW. Marginal improvements in gain:feed (G:F; quadratic, P = 0.058) and carcass yield (linear, P = 0.051) and reduction in backfat (quadratic, P = 0.074) were also observed with increasing SID lysine. The quadratic polynomial models predicted maximum ADG and G:F at 0.62 and 0.63% SID lysine, respectively. The broken-line linear model predicted no further improvement in G:F over 0.55% SID lysine. In Exp. 2, 224 pigs (PIC 327 × 1050, initially 109.4 kg) were used in a 20-d trial with 7 pigs per pen and 7 to 8 pens per treatment. Dietary treatments included 4 concentrations of CP (10, 11, 12, or 13%) that were formed by reducing the amount of L-lysine HCl in a corn-soybean meal diet. Increasing CP increased (linear, P < 0.05) ADG and ADFI with the greatest responses observed in pigs fed the diet with 12% CP. Increasing dietary CP also improved (linear, P < 0.05) G:F, final BW, and hot carcass weight (HCW). In Exp. 3, 238 pigs (DNA 600 × 241, initially 111.8 kg) were used in a 26-d trial with 7 to 8 pigs and 6 pens per treatment. Dietary treatments included 5 concentrations of CP (9, 10, 11, 12, or 13%). Increasing CP improved (quadratic, P < 0.05) ADG and G:F with the greatest response observed in pigs fed 13% CP. Increasing CP marginally increased (quadratic, P < 0.074) HCW, with the greatest response observed in pigs fed 12% CP. In conclusion, the SID lysine requirement for pigs from 100 to 122 kg was 0.55 to 0.63% depending on the response criteria with performance maximized with diets containing 12 to 13% CP.

Ammonia induces Treg/Th1 imbalance with triggered NF-κB pathway leading to chicken respiratory inflammation response

Ammonia (NH₃) is a severe air pollutant and a component of haze (PM2.5). The respiratory tract is the first route of exogenous ammonia's entry into the human and animal body. Many studies have suggested that exposure to NH₃ is associated with a higher risk of respiratory tract tracheitis; however, the underlying mechanism remains unclear. In this study, chicken tracheas were used as a model to investigate toxic effects and genetic changes induced by NH₃ exposure, as evaluated by scanning electron microscopy (SEM) and bioinformatic analyses. The transcript analysis illustrated that NH₃ exposure caused immune disorders, which play key roles in regulating inflammatory responses from NH₃ exposure. Therefore, we carried out Real-time quantitative PCR (RT-PCR) and Western Blot analyses to detect the immune response genes; Treg/Th1, Th2 and Th17 secretions were found that led to inflammatory responses. Next, we also detected the NF-κB pathway and downstream genes, accompanied by cytochromes P450 (CYPs), antioxidative genes, and heat shock proteins (HSPs). Our results are consistent with transcriptome detection, indicating that ammonia has a negative effect on immune responses and causes inflammatory injury of the trachea. This study provided baseline information for exploration of the molecular mechanism of NH₃-PM2.5 induced respiratory diseases.

Metabolic profile analysis of free amino acids in experimental autoimmune uveoretinitis rat plasma

AIM

To determine the differences of amino acid (AA) levels in experimental autoimmune uveoretinitis (EAU).

METHODS

AA analysis of the plasma samples in EAU rats induced by interphotoreceptor retinoid-binding protein emulsion were performed with high performance liquid chromatography (HPLC) and phenylisothiocyanate (PITC) pre-column derivation methods were performed. Using partial least squares discriminant analysis (PLS-DA), the potential biomarkers were identified in EAU rat plasma, and the metabolic pathways related to EAU were further analyzed.

RESULTS

The method results showed that linear (r≥0.9957), intra-day reproducible [relative standard deviation (RSD)=0.04%-1.33%], inter-day reproducible (RSD=0.06%-2.07%), repeatability (RSD=0.03%-0.89%), stability (RSD=0.05%-2.48%) and recovery (RSD=1.98%-4.39%), with detection limits of 0.853-11.4 ng/mL. The metabolic profile in EAU rats was different from that in the control groups five AAs concentrations were increased and nine AAs were reduced. Moreover, five metabolic pathways were related to the development of EAU.

CONCLUSION

The developed method is a simple, rapid and convenient for determination of AAs in EAU rat plasma, and these findings will provide a comprehensive insight on the metabolic profiling of the pathological changes in EAU.