Nitrogen and lysine utilization efficiencies, protein turnover, and blood urea concentrations in crossbred grower pigs at marginal dietary lysine concentration.

Nitrogen utilization efficiency (NUE) and lysine utilization efficiency (LUE) are key indicators of sustainable pork production and vary depending on nutritional and non-nutritional factors. The objective was to study NUE and LUE together with concentrations of blood urea nitrogen (BUN) and other metabolites in growing pigs fed diets with marginal Lys concentrations at 11-13 wk (40.5 kg mean BW) and 14 to 16 wk (60.2 kg mean BW). The cereal grain-soybean meal-based diets contained 10.6 and 7.9 g Lys/kg DM in periods 1 and 2, respectively. Feed intake and BW were measured for 508 individually penned pigs, and blood samples were collected 5 h after morning feeding at weeks 13 and 16. A subgroup of 48 barrows was used in a nitrogen (N) metabolism trial at weeks 13 and 16. In this subgroup, the mean N retention of pigs (27.3 g N/d) and mean LUE (70%) were not different between the periods, but NUE was higher in period 1 (47%) than in period 2 (43%) (P < 0.001). After administration of a single dose of 15N labeled glycine and measurement of 15N recovery in urine, the calculated whole-body protein turnover did not differ between the periods. The rate of protein synthesis was positively correlated with NUE (P < 0.001), but protein degradation was not. Excretion of urea-N in urine accounted for 80% of the total urinary N and was positively correlated with BUN. The N retention of all 508 pigs was estimated using an equation that was derived from the N metabolism data. N retention was on average 31.4 g/d, equal in both periods, and higher in barrows than in gilts in period 2, but not in period 1 (P = 0.003). The calculated NUE was, on average, 47% and was lower in barrows than in gilts (P < 0.001) and higher in period 1 than in period 2 (P < 0.001). The calculated LUE was, on average, 71%, and was lower in barrows than in gilts in period 2, but not in period 1 (P < 0.001). The BUN concentration was higher in barrows than in gilts (P < 0.001) and higher in period 1 than in period 2 (P < 0.001). BUN concentration was negatively correlated with NUE in Periods 1 (r = -0.50) and 2 (r = -0.15) (P < 0.05). We concluded that the maximum LUE was in the range of 70-72% under the conditions of this study, and only small differences between the periods and sexes existed. Protein synthesis, rather than degradation, appears to affect NUE. BUN concentration may be useful for estimating NUE in a large group of animals fed a diet with a marginal Lys concentration.

Increasing the utilization of protein and amino acids by pigs is an effective tool for improving the sustainability of pork production. This study showed that the utilization of lysine, the limiting amino acid in pigs, can reach 72% in growing pigs aged 11­16 wk when fed diets based on cereal grains and soybean meal. The average utilization of total nitrogen was 47%, with high variation among the pigs. Higher nitrogen utilization was associated with lower concentration of urea in the blood. This indicates that the blood urea concentration is an easy-to-determine proxy trait for nitrogen utilization in pigs when the concentration of lysine in the feed is low. Only small differences were observed between gilts and barrows during the investigation period. Nitrogen utilization increased when pigs had a higher rate of whole-body protein synthesis, which was associated with anabolic hormone concentrations in the blood.

Microbiome-derived cobalamin and succinyl-CoA as biomarkers for improved screening of anal cancer.

Human papillomavirus can cause preinvasive, high-grade squamous intraepithelial lesions (HSILs) as precursors to cancer in the anogenital area, and the microbiome is suggested to be a contributing factor. Men who have sex with men (MSM) living with human immunodeficiency virus (HIV) have a high risk of anal cancer, but current screening strategies for HSIL detection lack specificity. Here, we investigated the anal microbiome to improve HSIL screening. We enrolled participants living with HIV, divided into a discovery (n = 167) and validation cohort (n = 46), and who were predominantly (93.9%) cisgender MSM undergoing HSIL screening with high-resolution anoscopy and anal biopsies. We identified no microbiome composition signatures associated with HSILs, but elevated levels of microbiome-encoded proteins producing succinyl coenzyme A and cobalamin were significantly associated with HSILs in both cohorts. Measurement of these candidate biomarkers alone in anal cytobrushes outperformed anal cytology as a diagnostic indicator for HSILs, increasing the sensitivity from 91.2% to 96.6%, the specificity from 34.1% to 81.8%, and reclassifying 82% of false-positive results as true negatives. We propose that these two microbiome-derived biomarkers may improve the current strategy of anal cancer screening.

Factors Influencing Proteolysis and Protein Utilization in the Intestine of Pigs: A Review.

Pigs are among the most important farm animals for meat production worldwide. In order to meet the amino acid requirements of the animals, pigs rely on the regular intake of proteins and amino acids with their feed. Unfortunately, pigs excrete about two thirds of the used protein, and production of pork is currently associated with a high emission of nitrogen compounds resulting in negative impacts on the environment. Thus, improving protein efficiency in pigs is a central aim to decrease the usage of protein carriers in feed and to lower nitrogen emissions. This is necessary as the supply of plant protein sources is limited by the yield and the cultivable acreage for protein plants. Strategies to increase protein efficiency that go beyond the known feeding options have to be investigated considering the characteristics of the individual animals. This requires a deep understanding of the intestinal processes including enzymatic activities, capacities of amino acid transporters and the microbiome. This review provides an overview of these physiological factors and the respective analyses methods.

Metaproteomics Reveals Alteration of the Gut Microbiome in Weaned Piglets Due to the Ingestion of the Mycotoxins Deoxynivalenol and Zearalenone.

The ingestion of mycotoxins can cause adverse health effects and represents a severe health risk to humans and livestock. Even though several acute and chronic effects have been described, the effect on the gut metaproteome is scarcely known. For that reason, we used metaproteomics to evaluate the effect of the mycotoxins deoxynivalenol (DON) and zearalenone (ZEN) on the gut microbiome of 15 weaned piglets. Animals were fed for 28 days with feed contaminated with different concentrations of DON (DONlow: 870 µg DON/kg feed, DONhigh: 2493 µg DON/kg feed) or ZEN (ZENlow: 679 µg ZEN/kg feed, ZENhigh: 1623 µg ZEN/kg feed). Animals in the control group received uncontaminated feed. The gut metaproteome composition in the high toxin groups shifted compared to the control and low mycotoxin groups, and it was also more similar among high toxin groups. These changes were accompanied by the increase in peptides belonging to Actinobacteria and a decrease in peptides belonging to Firmicutes. Additionally, DONhigh and ZENhigh increased the abundance of proteins associated with the ribosomes and pentose-phosphate pathways, while decreasing glycolysis and other carbohydrate metabolism pathways. Moreover, DONhigh and ZENhigh increased the abundance of the antioxidant enzyme thioredoxin-dependent peroxiredoxin. In summary, the ingestion of DON and ZEN altered the abundance of different proteins associated with microbial metabolism, genetic processing, and oxidative stress response, triggering a disruption in the gut microbiome structure.