Reduced dietary nitrogen with a high Lys:CP ratio restricted dietary N excretion without negatively affecting weaned piglets.

We hypothesized that balancing the content of exogenous amino acids, especially lysine, to reduce protein content in swine diets could reduce nitrogen (N) pollution associated with animal husbandry. Two experiments (45 d each experiment) were performed on weaned piglets (Duroc × Landrace × Yorkshire, 28 d of age) to test this and to determine the optimal lysine to crude protein (Lys:CP) ratio in diet. In Exp. 1, 12 piglets (6 replicates [n = 6]) were fed diets containing different levels of CP (17% and 20%) but the same level of Lys. Increased CP content resulted in significant increases (P < 0.05) of average daily gain (ADG), average daily feed intake (ADFI), and body weight (BW), but did not affect the feed to gain ratio. In Exp. 2, 24 piglets (8 replicates [n = 8]) were fed 1 of 3 diets as follows: 1) 20% CP with a regular Lys:CP ratio (6.23%, control); 2) 17% CP with a reduced Lys:CP ratio (6.14%, LL); or 3) 17% CP with a standard Lys:CP ratio (7.32%, SL). The ADG, final BW, serum concentrations of growth hormone and insulin-like growth factor-1, villus height in the jejunum, and villus height to crypt depth ratio were the lowest in piglets fed LL diet, whereas blood urea N concentration was the lowest and the value of lipase activity was the highest in the piglets fed SL diet. The SL diet did not affect growth performance, intestinal morphology, or serum hormone concentrations, indicating that reduced dietary N with a high Lys:CP ratio can efficiently reduce dietary N excretion without negatively affecting weaned piglets.

Effects of dietary lysine restriction on inflammatory responses in piglets.

The aim of this study was to investigate the effects of lysine restriction on inflammatory responses in piglets. 38 male piglets with similar body weight of 9.62 kg were randomly divided into control group (basal diet) and lysine-restricted group (diet containing 70% lysine of the control diet). The results showed that lysine restriction increased the serum concentration of IgG an IgM. Piglets fed the lysine-restricted diet exhibited overexpression of interleukin-8 (IL-8) in the kidney (P < 0.05) and IL-6 and IL-4 in the spleen (P < 0.05). The mRNA abundances of IL-4 in the kidney (P < 0.05) and IL-10 in the liver (P < 0.05) were significantly lower in the lysine-restricted group compared with the control group. Meanwhile, lysine restriction increased the mRNA level of Tlr8 in the kidney (P < 0.05) but decreased the mRNA level of Tlr8 in the liver (P < 0.05). Finally, lysine restriction markedly enhanced extracellular signal regulated kinases 1/2 (ERK1/2) phosphorylation in the kidney and liver and nuclear transcription factor kappa B (NF-κB) was activated in the liver and spleen in response to dietary lysine restriction. In conclusion, lysine restriction affected inflammatory responses in the kidney, liver, and spleen via mediating serum antibody volume, inflammatory cytokines, Tlrs system, and ERK1/2 and NF-κB signals in piglets.

Roles of Dietary Amino Acids and Their Metabolites in Pathogenesis of Inflammatory Bowel Disease.

Inflammatory Bowel Disease (IBD) is a kind of chronic inflammation, which has increasing incidence and prevalence in recent years. IBD mainly divides into Crohn's disease (CD) and ulcerative colitis (UC). It is hard to cure IBD completely, and novel therapies are urgently needed. Amino acids (AAs) and their metabolites are regarded as important nutrients for humans and animals and also play an important role in IBD amelioration. In the present study, the potential protective effects of AAs and their metabolites on IBD had been summarized with the objective to provide insights into IBD moderating using dietary AAs and their metabolites as a potential adjuvant therapy.

Effects of Lysine deficiency and Lys-Lys dipeptide on cellular apoptosis and amino acids metabolism.

SCOPE: Lysine (Lys) is a common limiting amino acids (AA) for humans and animals and plays an important role in cell proliferation and metabolism, while metabolism of Lys deficiency and its dipeptide is still obscure. Thus, this study mainly investigated the effects of Lys deficiency and Lys-Lys dipeptide on apoptosis and AA metabolism in vitro and in vivo models. METHODS AND RESULTS: Lys deficiency induced cell-cycle arrest and apoptosis and upregulated Lys transporters in vitro and in vivo. SLC7A11, a cystine-glutamate antiporter, was markedly upregulated by Lys deficiency and then further mediated cystine uptake and glutamate release, which was negatively regulated by cystine and glutamate transporters. Meanwhile, Lys deprivation upregulated pept1 expression, which might improve Lys-Lys dipeptide absorption to compensate for the reduced Lys availability. Lys-Lys dipeptide alleviated Lys deficiency induced cell-cycle arrest and apoptosis and influenced AA metabolism. Furthermore, the mammalian target of rapamycin signal might be involved in sensing cellular Lys starvation and Lys-Lys dipeptide. CONCLUSIONS: Altogether, these studies suggest that Lys deficiency impairs AA metabolism and causes apoptosis. Lys-Lys dipeptide serves as a Lys source and alleviates Lys deficiency induced cellular imbalance.

Effects of Glutamate and Aspartate on Serum Antioxidative Enzyme, Sex Hormones, and Genital Inflammation in Boars Challenged with Hydrogen Peroxide.

Background. Oxidative stress is associated with infertility. This study was conducted to determine the effects of glutamate and aspartate on serum antioxidative enzymes, sex hormones, and genital inflammation in boars suffering from oxidative stress. Methods. Boars were randomly divided into 4 groups: the nonchallenged control (CON) and H2O2-challenged control (BD) groups were fed a basal diet supplemented with 2% alanine; the other two groups were fed the basal diet supplemented with 2% glutamate (GLU) or 2% aspartate (ASP). The BD, GLU, and ASP groups were injected with hydrogen peroxide (H2O2) on day 15. The CON group was injected with 0.9% sodium chloride solution on the same day. Results. Dietary aspartate decreased the malondialdehyde (MDA) level in serum (P < 0.05) compared with the BD group. Additionally, aspartate maintained serum luteinizing hormone (LH) at a relatively stable level. Moreover, glutamate and aspartate increased transforming growth factor-ß1 (TGF-ß1) and interleukin-10 (IL-10) levels in the epididymis and testis (P < 0.05) compared with the BD group. Conclusion. Both glutamate and aspartate promoted genital mRNA expressions of anti-inflammatory factors after oxidative stress. Aspartate more effectively decreased serum MDA and prevented fluctuations in serum sex hormones after H2O2 challenge than did glutamate.