PSX-B-3 Effect of infrequent nitrogen supplementation on forage utilization

Our objective was to determine the effects of differing levels of supplemental nitrogen offered daily, or every 3 d on nitrogen balance, forage intake, and digestibility in cattle consuming low-quality forage. Five ruminally cannulated Angus × Hereford steers (BW = 350 ± 71 kg) were used in a 5 × 5 Latin square design. Steers consumed low-quality bluestem hay (67.7% NDF, 4.7% CP; DM basis) ad libitum. Treatments were no supplement (CON), or cottonseed meal offered at levels providing 120 mg N/kg BW each day (L/1D) or every 3 d (L/3D), 240 mg N/kg BW every 3 d (M/3D), or 360 mg N/kg BW every 3 d (H/3D). Hay, ort, urine, and fecal samples were collected during the last 6 d of each period and ruminal fluid during the last 3 d. Total digestible OM intake was greater in L/1D (6660 g/d; P < 0.01) compared to CON (4498 g/d) and increased linearly in steers supplemented intermittently (5145, 6170, and 6698 g/d for L/3D, M/3D, and H3/D, respectfully; P < 0.01). Total tract OM digestibility was similar between CON and L/1D, L/3D, and H/3D (58.21, 61.21, 60.82, and 60.91%, respectively; P ≥ 0.10) but was greater in M/3D steers (63.30%; P ≤ 0.02). Reducing frequency of protein supplementation to every 3-d improved forage intake and utilization similar to daily supplementation when provided at medium (240 mg N/kg BW) or high (360 mg N/kg BW) levels. Improved efficiency of nitrogen recycling likely buffered disruptions in protein supply, maintaining intake and digestibility of low-quality forage without daily supplementation. Supplementation of protein every 3 d at 240 g N/kg BW appears to the most biologically effective strategy, increasing intake of LQF and maximizing OM digestibility and N utilization.

Vitamin K Vitamers Differently Affect Energy Metabolism in IPEC-J2 Cells

The fat-soluble vitamin K (VK) has long been known as a requirement for blood coagulation, but like other vitamins, has been recently recognized to play further physiological roles, particularly in cell development and homeostasis. Vertebrates cannot de novo synthesize VK, which is essential, and it can only be obtained from the diet or by the activity of the gut microbiota. The IPEC-J2 cell line, obtained from porcine small intestine, which shows strong similarities to the human one, represents an excellent functional model to in vitro study the effect of compounds at the intestinal level. The acute VK treatments on the bioenergetic features of IPEC-J2 cells were evaluated by Seahorse XP Agilent technology. VK exists in different structurally related forms (vitamers), all featured by a naphtoquinone moiety, but with distinct effects on IPEC-J2 energy metabolism. The VK1, which has a long hydrocarbon chain, at both concentrations (5 and 10 μM), increases the cellular ATP production due to oxidative phosphorylation (OXPHOS) by 5% and by 30% through glycolysis. The VK2 at 5 μM only stimulates ATP production by OXPHOS. Conversely, 10 μM VK3, which lacks the long side chain, inhibits OXPHOS by 30% and glycolysis by 45%. However, even if IPEC-J2 cells mainly prefer OXPHOS to glycolysis to produce ATP, the OXPHOS/glycolysis ratio significantly decreases in VK1-treated cells, is unaffected by VK2, and only significantly increased by 10 μM VK3. VK1, at the two concentrations tested, does not affect the mitochondrial bioenergetic parameters, while 5 μM VK2 increases and 5 μM VK3 reduces the mitochondrial respiration (i.e., maximal respiration and spare respiratory capacity). Moreover, 10 μM VK3 impairs OXPHOS, as shown by the increase in the proton leak, namely the proton backward entry to the matrix space, thus pointing out mitochondrial toxicity. Furthermore, in the presence of both VK1 and VK2 concentrations, the glycolytic parameters, namely the glycolytic capacity and the glycolytic reserve, are unaltered. In contrast, the inhibition of glycoATP production by VK3 is linked to the 80% inhibition of glycolysis, resulting in a reduced glycolytic capacity and reserve. These data, which demonstrate the VK ability to differently modulate IPEC-J2 cell energy metabolism according to the different structural features of the vitamers, can mirror VK modulatory effects on the cell membrane features and, as a cascade, on the epithelial cell properties and gut functions: balance of salt and water, macromolecule cleavage, detoxification of harmful compounds, and nitrogen recycling.

Effect of activated carbon on the nitrogen balance in broilers, soil and corn forage fertilized with the excreta of the broilers

Objective: To evaluate the contribution and nitrogen retention in broilers supplementedwith activated carbon (CaAc), as well and in soils and corn forage fertilized with the excretaof chickens that consumed CaAc.Design / methodology / approach: Chickens individually housed received diets with fourlevels of CaAc: 0, 0.15, 0.30 and 0.45% and their nitrogen balance was determined usingthe total collection of excreta. 200 g of the chicken excreta were taken and mixed with 2 kgof soil (S + E) in plastic trays and watered every 15 d. On day 1 and 60, samples weretaken to perform the nitrogen balance assessment. The S + E mixtures were added to 17kg of agricultural soil in pots to produce corn forage for 100 d, their yield and compositionwere recorded. The results were analyzed with an ANOVA and linear regression.Findings / conclusion: In chickens, nitrogen retention showed a quadratic response (P<0.05); In the S + E mixtures, the percentage (P <0.01) and final nitrogen content (P <0.05) had also quadratic responses, and in the forage, the nitrogen percentage showed a cubicresponse (P <0.05) respect to the increases in the addition of CaAc in the chicken´s diet. CaAc can be used to improve the nitrogen efficiency in chickens and for nitrogen recycling through the integration of excreta in agricultural soils and its extraction in corn forage.

Taxonomic and Enzymatic Characterization of Flocculibacter collagenilyticus gen. nov., sp. nov., a Novel Gammaproteobacterium With High Collagenase Production

Collagens from marine animals are an important component of marine organic nitrogen. Collagenase-producing bacteria and their collagenases play important roles in collagen degradation and organic nitrogen recycling in the ocean. However, only a few collagenase-producing marine bacteria have been so far discovered. Here, we reported the isolation and characterization of a collagenase-secreting bacterium, designated strain SM1988T, isolated from a green alga Codium fragile sample. Strain SM1988T is a Gram-negative, aerobic, oxidase-, and catalase-positive, unipolar flagellated, and rod-shaped bacterium capable of hydrolyzing casein, gelatin and collagens. Phylogenetic analysis revealed that strain SM1988T formed a distinct phylogenetic lineage along with known genera within the family Pseudoalteromonadaceae, with 16S rRNA gene sequence similarity being less than 93.3% to all known species in the family. Based on the phylogenetic, genomic, chemotaxonomic and phenotypic data, strain SM1988T was considered to represent a novel species in a novel genus in the family Pseudoalteromonadaceae, for which the name Flocculibacter collagenilyticus gen. nov., sp. nov. is proposed, with the type strain being SM1988T (= MCCC 1K04279T = KCTC 72761T). Strain SM1988T showed a high production of extracellular collagenases, which had high activity against both bovine collagen and codfish collagen. Biochemical tests combined with genome and secretome analyses indicated that the collagenases secreted by strain SM1988T are serine proteases from the MEROPS S8 family. These data suggest that strain SM1988T acts as an important player in marine collagen degradation and recycling and may have a promising potential in collagen resource utilization.

In situ measurements of nitrogen contents in formerly subducted rocks reveal variable behaviour of nitrogen during fluid-rock interaction.

<p>Nitrogen recycling from the Earth’s surface to the mantle through subduction zones is a key component of the long term global nitrogen cycle. Data on the nitrogen contents of formerly subducted rocks is key to constraining this flux and to understanding nitrogen behaviour during subduction dehydration. Studies have so far been restricted to analyses of whole rocks or mineral separates, which masks textural controls and mineral heterogeneity. Here we present the first <em>in situ</em> SIMS analyses of nitrogen contents in white micas and other minerals from a suite of subduction-related crustal rocks. We determine the nitrogen distribution in these rocks and explore the behaviour of nitrogen, compared to other fluid-mobile elements, during subduction and fluid-rock interaction. Samples from three localities were investigated: blueschist and eclogite from the Raspas Complex, Ecuador; blueschist and eclogite from the Franciscan mélange (Jenner, California); eclogite and garnet-phengite quartzite from Lago di Cignana, Italy.</p><p>Our data confirm that white mica (phengite, paragonite) is the primary host for nitrogen across all samples. Both phengite and paragonite contain substantial amounts of nitrogen (up to 320 ppm), but the concentrations vary widely across different samples. Chlorite replacing garnet in eclogites and blueschists contains little nitrogen. In contrast, chlorite occurring with garnet, phengite (108 - 270 ppm N), glaucophane and titanite in the matrix of a blueschist from Jenner contains measurable quantities of nitrogen (10 - 83 ppm). Other minerals (clinopyroxene, amphibole, epidote, titanite, garnet) contain little nitrogen (<5 ppm) in all samples.</p><p>A blueschist from Raspas contains coexisting phengite and paragonite, in addition to garnet, glaucophane, epidote, and accessory albite and carbonate. Nitrogen preferentially partitions into phengite (117 - 243 ppm) over paragonite (31 - 118 ppm). Albite also contains some nitrogen (15 ppm). Silicon contents of phengite vary from 3.32 – 3.40 a.f.u. Decrease in silicon is correlated with decrease in nitrogen and boron, and increase in lithium. These trends can be explained by growth of paragonite during retrograde fluid-rock interaction and redistribution of these elements between phengite, paragonite and glaucophane.</p><p>Variability in nitrogen concentrations in other samples which have undergone peak or retrograde fluid-rock interaction, and contain only phengite as a nitrogen-bearing phase, cannot be explained by redistribution. Different samples display either no change in nitrogen, or addition of nitrogen during fluid-rock interaction, as recorded by different generations of phengite. No correlation between nitrogen contents of the samples and P-T conditions was observed, but this was likely due to the large range of protoliths in this study.</p><p>Our results demonstrate that nitrogen behaviour during fluid-rock interaction is complex and can be variable between samples, and that <em>in situ</em> data can inform understanding of the processes controlling N distribution.</p>

Urea nitrogen recycling via gut symbionts increases in hibernators over the winter fast

Hibernation is a mammalian strategy that uses metabolic plasticity to reduce energy demands and enable long-term fasting. Fasting mitigates winter food scarcity but eliminates dietary nitrogen, jeopardizing body protein balance. Here, we reveal gut microbiome-mediated urea nitrogen recycling in hibernating 13-lined ground squirrels (TLGS). Ureolytic gut microbes incorporate urea nitrogen into organic compounds that are absorbed by the host, with the nitrogen reincorporated into the TLGS protein pool. Urea nitrogen recycling is greatest after prolonged fasting in late winter, when urea transporter abundance in gut tissue and urease gene abundance in the microbiome are highest. These results reveal a functional role for the gut microbiome in hibernation and suggest mechanisms by which urea nitrogen recycling contributes to protein balance in other monogastric animals, including humans.One Sentence SummaryGround squirrels and their gut symbionts benefit from urea nitrogen recycling throughout hibernation.