Lys Concentration Research Articles

On farm precision feeding of gestating sows based on energy and amino acids on farrowing performances and feeding behavior over 3 consecutive gestations.

Gestating sows are often fed a single diet throughout their gestation cycle, leading to situations of nutrients deficiency or excess at the individual level. The purpose of this study was to characterize, over 3 consecutive cycles, the impact of a precision feeding (PF), i.e., dietary supplies adjusted at individual level in terms of quantity (energy intake) and quality (standardized ileal digestible (SID) lysine (Lys) intake), on gestating sows' productive performance, feeding behavior, environmental outputs, and health status compared with sows fed a conventional feeding (CF, i.e., fixed SID Lys intake). At the start of the trial, 2 batches of 20 Landrace × Large White gestating sows were allocated to one of the 2 feeding strategies (PF vs. CF), based on their parity (1, 2, or 3 and more), body weight, and backfat thickness (BT) 3 days after insemination. The PF strategy consisted in mixing with automatic feeders 2 iso-energetic diets (9.8 MJ/kg of net energy with 3.3 and 8.5g SID Lys/kg, respectively) in variable proportions at individual and daily levels, whereas for the CF strategy these proportions remained constant throughout gestation (73% and 27%, respectively, resulting in an SID Lys concentration of 4.7g/kg). Sows were followed over 3 consecutive gestations and the sows remained allocated to the same strategy throughout the study. Some sows were culled before the end of the study and were replaced by other sows who therefore performed only 1 or 2 gestations during the study. Thus, 106 gestations and lactations from 51 sows were fully studied and their data analyzed. The PF strategy allowed the sows to reach more closely the expected BT values at farrowing across cycles than the CF strategy (P < 0.001). The PF sows consumed 16% less SID Lys per gestation than the CF sows (P < 0.001), resulting in a 4% improvement in N efficiency (P < 0.001), with no impact on performance at farrowing (P > 0.10). The sows consumed their daily ration in a single visit whatever the feeding strategy (P = 0.41), but CF sows spent more time in the feeder in cycles 2 and 3 (P < 0.001). Thus, compared to the CF strategy implemented by farmers, the individual and daily nutritional supplies implemented with the PF strategy were more efficient in enabling sows to achieve body condition objectives at farrowing over the long term, also with a reduced SID Lys intake and an improved N efficiency without negative impact on farrowing performances.

Varying the ratio of Lys: Met through enhancing methionine supplementation improved milk secretion ability through regulating the mRNA expression in bovine mammary epithelial cells under heat stress.

The ratio of lysine (Lys) to methionine (Met) with 3.0: 1 is confirmed as the "ideal" profile for milk protein synthesis, but whether this ratio is suitable for milk protein synthesis under HS needs to be further studied. To evaluate the molecular mechanism by which HS and Lys to Met ratios affect mammary cell functional capacity, an immortalized bovine mammary epithelial cell line (MAC-T) is incubated with 5 doses of Met while maintaining a constant concentration of Lys. The MAC-T cells was treated for 6 h as follow: Lys: Met 3.0: 1 (control 37°C and IPAA 42°C) or treatments under HS (42°C) with different ratios of Lys: Met at 2.0: 1 (LM20), 2.5: 1 (LM25), 3.5: 1 (LM35) and 4.0: 1 (LM40). RNA sequencing was used to assess transcriptome-wide alterations in mRNA abundance. The significant difference between control and other groups was observed base on PCA analysis. A total of 2048 differentially expressed genes (DEGs) were identified in the IPAA group relative to the control group. Similarly, 226, 306, 148, 157 DEGs were detected in the LM20, LM25, LM35 and LM40 groups, respectively, relative to the IPAA group. The relative mRNA abundance of HSPA1A was upregulated and anti-apoptotic genes (BCL2L1 and BCL2) was down-regulated in the IPAA group, compared to the control group (p < 0.05). Compared with the IPAA group, the relative mRNA abundance of anti-apoptotic genes and casein genes (CSN1S2 and CSN2) was up-regulated in the LM25 group (p < 0.05). The DEGs between LM25 and IPAA groups were associated with the negative regulation of transcription RNA polymerase II promoter in response to stress (GO: 0051085, DEGs of BAG3, DNAJB1, HSPA1A) as well as the mTOR signaling pathway (ko04150, DEGs of ATP6V1C2, WNT11, WNT3A, and WNT9A). Several DEGs involved in amino acids metabolism (AFMID, HYKK, NOS3, RIMKLB) and glycolysis/gluconeogenesis (AFMID and MGAT5B) were up-regulated while DEGs involved in lipolysis and beta-oxidation catabolic processes (ALOX12 and ALOX12B) were down-regulated. These results suggested that increasing Met supply (Lys: Met at 2.5: 1) may help mammary gland cells resist HS-induced cell damage, while possibly maintaining lactation capacity through regulation of gene expression.

141 Determination of the optimum standardized ileal digestible lysine for nursery pigs fed high levels of dietary fiber

Abstract An experiment was conducted to determine the optimum standardized ileal digestible (SID) Lys for nursery swine-fed high levels of dietary fiber. A total of 2,525 pigs [PIC 337 × 1050, initial body weight (BW) = 6.5 kg], placed in pens of 36 mixed-sex pigs, were used in a 42-d trial. Pigs were allotted to 1 of 5 dietary treatments with 14 replicates per treatment. Increasing dietary SID Lys concentrations of 1.14, 1.22, 1.30, 1.38, and 1.45% were obtained by blending the 1.14% and the 1.45% SID Lys diets via Big Dutchman DryExact Pro feeding system (Big Dutchman, Holland, MI). The different SID Lys levels were obtained by changing the inclusion rate of soybean meal, which ranged from 15 to 28%. The experimental diets contained sugar beet pulp and soy hulls, resulting in an NDF level of 10.5%. Experimental diets were fed for 17 d and followed by a common corn, soybean meal, and 10% DDGS diet with 1.30% SID Lys from d 17 to 42. Pigs were weighed on d 0, 17, and 42 to calculate average daily gain (ADG), average daily feed intake (ADFI) and gain to feed ratio (G:F). From d 0 to 17, a quadratic (P &amp;lt; 0.05) improvement in ADG and ADFI was observed for pigs fed increasing SID Lys up to 1.38%, plateauing thereafter. Pigs fed increasing SID Lys had linearly (P = 0.001) improved G:F (Table 1). From d 17 to 42, there was no evidence (P &amp;gt; 0.10) for differences in ADG, yet ADFI increased linearly (P = 0.004) while G:F decreased linearly (P = 0.001) for pigs previously fed increasing concentrations of SID Lys. Overall (d 0 to 42) for pigs fed increasing SID Lys, ADG and ADFI increased quadratically (P &amp;lt; 0.05) up to 1.38% SID Lys, whereas G:F increased linearly (P = 0.001) up to 1.45% SID Lys. Mortality and removal rate was quadratically influenced (P &amp;lt; 0.05) by feeding increasing SID Lys. Our findings suggest feeding weaned pigs from d 0 to 17 a diet containing 1.38% SID Lys is optimal for growth performance while minimizing mortality and removal rate.

Effects of feeding rumen-protected lysine during the postpartum period on performance and amino acid profile in dairy cows: A meta-analysis

Lysine is one of the limiting AA in the diets of dairy cows and is typically fed as rumen-protected Lys (RPL). We hypothesized that supplementation of RPL during the postpartum period would improve the productive performance in dairy cows. Objectives were to use meta-analytic methods to explore the effects of feeding RPL on performance and blood AA profile in lactating dairy cows. An additional objective was to identify an optimal concentration (%) of Lys in MP (LYSMP) and determine if responses to LYSMP were associated with the concentration (%) of Met in MP (METMP). The literature was systematically reviewed, and 13 experiments, comprising 40 treatment means and 594 lactating cows, were included in the meta-analysis. All experiments had a nonsupplemental control (CON; n = 17 treatment means), or a group supplemented with RPL (n = 23 treatment means). Cows supplemented with RPL were supplied additionally with a mean (±standard deviation) 19.3 ± 10.3 g/d metabolizable Lys (5.1-40.6 g/d). Meta-analytical statistics were used to estimate the weighted mean difference in STATA. Mixed models were fitted to the data to investigate the linear and quadratic effects of LYSMP, METMP, and interactions between LYSMP and METMP. All models included the random effect of experiment and weighting by the inverse of the SE of the means squared. Cows that began receiving RPL in early lactation (≤90 DIM) or for an extended duration (≥70 DIM) produced 1.51 kg/d more milk compared with CON cows. Increasing digestible LYSMP from 6.5% to 8.5% linearly increased yields of milk, FCM, ECM, and milk fat by 1.8, 2.5, 2.4, and 0.10 kg/d, respectively, and tended to increase milk protein yield and body weight gain by 0.07 and 0.09 kg/d, respectively, without a concurrent increase in DMI. Interactions between the linear effects of LYSMP and METMP were observed for FCM/DMI or ECM/DMI. In a diet with low METMP (e.g., 1.82% of MP), a digestible supply of 7.40% LYSMP would result in 1.46 and 1.47 kg/kg FCM/DMI or ECM/DMI, respectively; however, with high digestible METMP (e.g., 2.91% of MP), supplying 7.40% of digestible LYSMP would result in 1.68 and 1.62 kg/kg FCM/DMI or ECM/DMI, respectively. Increasing digestible LYSMP from 6.5% to 8.5% linearly increased blood concentrations of Lys by 16.6 µM, whereas blood concentrations of Met and Ala decreased by 4.6 and 6.0 µM, respectively. Nevertheless, an interaction was also observed between LYSMP and METMP for blood concentrations of total EAA because as METMP increased, the positive response to LYSMP on total EAA was also increased, suggesting a competitive mobilization of AA and their utilization in various body tissues. Only 4 out of the 13 experiments in this meta-analysis involved primiparous cows; thus, insufficient data were available to understand the role of supplemental RPL in primiparous cows. Collectively, feeding RPL improved productive performance, and the increments were maximized up to 9.25% of LYSMP in multiparous dairy cows.

Distinct Amino Acid Profile Characterizes Youth With or at Risk for Type 2 Diabetes.

Branched-chain amino acids (BCAA) and aromatic AAs (AAA) are associated with increased risk for type 2 diabetes in adults. Studies in youth show conflicting results. We hypothesized that an AA metabolomic signature can be defined to identify youth at risk for β-cell failure and the development of type 2 diabetes. We performed targeted AA metabolomics analysis on 127 adolescents (65 females, 15.5±1.9 years old, Tanner stage II-V) with normal weight or obesity across the spectrum of glycemia, with assessment of AA concentrations by mass spectrometry, at fasting and steady-state (SS) of a hyperinsulinemic-euglycemic clamp, with determination of insulin sensitivity (ISFFM). We measured insulin secretion during a 2-hour hyperglycemic clamp and calculated the disposition index (DIFFM), a measure of β-cell function. Our results showed that Gly and Gln/Glu were lower, whereas BCAA, Tyr and Lys concentrations were higher in the groups with obesity and dysglycemia compared with those with normal weight. Gly and Gln/Glu were positively related to IS and DIFFM, with opposite relationships observed for BCAA, AAA and Lys. We conclude that a metabolic signature of low Gly, low Gln/Glu and elevated BCAA, AAA and Lys may constitute a biomarker to identify youth at risk for β-cell failure.

Optimal protein concentration in diets for sows during the transition period.

The aim of the present study was to determine the optimal concentration of dietary protein required in transition diets for multiparous sows that enhance the farrowing process, colostrum production, and subsequent lactation performance. Forty-eight multiparous sows were allotted to one of six dietary treatments according to body weight (290 ± 3kg) and parity (3.8 ± 0.2) from day 108 of gestation until 24hafter the onset of farrowing. The diets were isoenergetic and contained increasing concentrations of dietary protein (expressed as standardized ileal digestible [SID] Lys) and were supplied at a daily feed supply of 3.8kg. On day 108 of gestation and days 2, 7, 14, 21, and 28 of lactation, body weight, and back fat thickness were recorded, and blood was sampled on day 108 of gestation, at the onset of farrowing, and days 3, 10, 17, and 24 of lactation from the sows for analysis of plasma metabolites. On day 115 of gestation, urine, and feces were collected for nitrogen (N) balance. The number of liveborn and stillborn piglets and time of birth were recorded and blood from every fourth piglet was sampled at birth for blood gas analysis. Piglets were weighed individually from birth until weaning, to estimate the colostrum and milk yield of the sows. Colostrum and milk samples were collected, and their compositions were determined. On days 3 and 28 of lactation, sows were injected with deuterium oxide to estimate body composition. The N utilization was maximized when the concentration of SID Lys in the transition diet was 6.06g/kg (P < 0.01). When urinary concentrations of urea were expressed relative to creatinine, the relative concentration of urea remained low until a dietary concentration of 6.08g SID Lys/kg, above which the relative concentration of urea increased (P < 0.01). Stillbirth rate increased linearly with increasing SID Lys concentration in the transition diet (P < 0.001), thus the concentration of SID Lys should be kept as low as possible without impairing sow performance excessively. A carry-over effect on milk yield was observed, showing that a dietary SID Lys concentration of 5.79g/kg during transition optimized milk production at an average yield of 13.5kg/d (P = 0.04). Increasing loss of body fat in lactation was observed with increasing SID Lys concentration in the transition diet (P = 0.03). In conclusion, the transition diet of multiparous sows should contain 5.79g SID Lys/kg when fed 3.8kg/d (13.0 MJ ME/kg), for a total SID Lys intake of 22g/d.

Effect of pH on the Poly(acrylic acid)/Poly(vinyl alcohol)/Lysozyme Complexes Formation.

The interactions between poly(acrylic acid) (PAA), poly(vinyl alcohol) (PVA), and lysozyme (Lys) in an aqueous environment at pHs of 2, 4, and 7.4 were discussed considering the experimental data obtained by turbidimetry, electrokinetic and rheological measurements, and FTIR analysis. It was found that the increase in PAA amount reduces the coacervation zone by shifting the critical pHcr1to higher values while the critical pHcr2 remains unchanged. The coacervation zone extended from 3.1-4.2 to 2.9-4.7 increasing the Lys concentration from 0.2% to 0.5%. The zeta potential measurements showed that the PAA-PVA-Lys mixture in water is the most stable in the pH range of 4.5-8. Zero shear viscosity exhibited deviations from additivity at both investigated pHs, and a maximum value corresponding to a maximum hydrodynamic volume was revealed at PAA weight fractions of 0.4 and 0.5 for pHs of 4 and 7.4, respectively. The binding affinity to Lys of PAA, established by molecular dynamics simulation, was slightly higher than that of PVA. The more stable complex was PAA-Lys formed in a very acidic environment; for that, a binding affinity of -7.1 kcal/mol was determined.

Synergistic Effect of Charged Amino Acids on the Stability and Fibril Formation of Lysozyme

AbstractOsmolytes alter the stability and aggregation of proteins. The effect of mixture of osmolytes is generally not a simple additive of their individual effects. Here, we examine the effect of different mixtures of charged amino acids (AAs) on the stability and fibrillation of lysozyme. Arg, Asp and Glu induce three‐state unfolding. The addition of Lys, Asp and Glu increases the thermal stability of lysozyme, whereas Arg does not alter the stability. The mixture of AAs destabilizes the intermediate, but the overall stability of lysozyme is increased. Arg with other AAs in the ratio of 1 : 0.5 and 1 : 1, and the equimolar ratio of Glu+Asp synergistically increases the stability, whereas the other mixtures counteract the stabilizing effects of each other. The apparent time taken for fibrillation is reduced with lower concentrations of Arg (≤0.75 M) and Glu (0.25 M) and at higher concentrations of Lys (1 M). In the mixed AAs, Arg and Lys with other AAs, and 1 : 1 ratio of Glu+Asp synergistically increases the fibrillation time. These observations suggest that Arg induces more synergistic stabilization and the presence of basic AAs in the mixture increases the fibrillation time compared to acidic AAs which show synergy only at equimolar concentrations.

130 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 102- to 127-kg Immunocastred Gilts and Boars

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) on growth performance of immunocastrated gilts and boars. A total of 3,519 split gender pigs [PIC 337×Camborough, initial body weight (BW) = 101.7 ± 3.89 kg] were used in a 21-d trial in 2 replicates. Following the immunization against gonadotropin-releasing hormone (administrated with Vivax, Zoetis, São Paulo, SP, Brazil) in both genders, pens of pigs were weighed, blocked by BW, and randomly allotted to 1 of 5 treatments. Treatments consisted of 1.69, 1.90, 2.11, 2.32, and 2.53 g of SID Lys:Mcal of ME, which corresponded to 80, 90, 100, 110, and 120% of PIC SID Lys recommendations for mixed gender between barrow and gilts. This resulted in 0.56, 0.63, 0.70, 0.77, and 0.84% SID Lys given that the treatment diets were corn-soybean-meal-based and contained 3,300 Kcal of ME/kg. There were 6 split gender pens∙treatment-1∙replicate-1 and 29 pigs/pen. Data were analyzed using generalized linear and nonlinear mixed models with a pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). There was no evidence of linear or quadratic SID Lys concentration by gender interaction (Table). Increasing SID Lys concentration improved average daily gain (ADG; quadratic, P &amp;lt; 0.01) and gain-to-feed ratio (G:F; quadratic, P &amp;lt; 0.01). The QP, BLL, and BLQ had a similar fit for the ADG and G:F. In the QP model, 95% and 100% of the ADG were achieved at 0.64 and 0.76% of SID Lys, respectively, and at 0.61 and 0.75% for G:F. The BLL and BLQ models estimated the breakpoint at 0.70% (95% CI: 0.65-0.74%) and 0.68% SID Lys (95% CI: 0.50-0.85%), for ADG, respectively. For G:F, the BLL, and BLQ models estimated the breakpoint at dietary SID Lys of 0.69% (95% CI: 0.52-0.86%) and 0.68% (95% CI: 0.58-0.78%), respectively. There was no evidence that increasing dietary SID Lys levels impacted the average daily feed intake or the removal and mortality rate. In the current trial the estimated optimum SID Lys:Mcal of ME ratio for 102- to 127-kg immunocastrated gilts and boars ranged from 2.06-2.30 (0.68-0.76% SID Lys based on a 3,300 kcal of ME/kg diet), depending on the statistical model.

Relationships between dietary rumen-protected lysine and methionine with the lactational performance of dairy cows: A meta-analysis.

Our objective was to examine the relationships of supplemental rumen-protected lysine (RPL) or lysine + methionine (RPLM) on lactational performance, plasma amino acids (AA) concentration, and nitrogen use efficiency of lactating dairy cows by using a meta-analysis approach. A total of 56 articles comprising 77 experiments with either RPL or RPLM supplementation were selected and analyzed using a mixed model methodology by considering the treatments and other potential covariates as fixed effects and different experiments as random effects. In early lactating cows, milk yield was linearly increased by RPL (β1 = 0.013; p<0.001) and RPLM (β1 = 0.014; p<0.028) but 3.5% fat-corrected milk (FCM) and energy-corrected milk (ECM) (kg/d) was increased by only RPL. RPL and RPLM did not affect dry matter intake (DMI) but positively increased (p<0.05) dairy efficiency (Milk yield/DMI and ECM/DMI). As a percentage, milk fat, protein, and lactose were unchanged by RPL or RPLM but the yield of all components was increased (p<0.05) by feeding RPL while only milk protein was increased by feeding RPLM. Plasma Lys concentration was linearly increased (p<0.05) with increasing supplemental RPL while plasma Met increased (p<0.05) by RPLM supplementation. The increase in plasma Lys had a strong linear relationship (R2 = 0.693 in the RPL dataset and R2 = 0.769 in the RPLM dataset) on milk protein synthesis (g/d) during early lactation. Nitrogen metabolism parameters were not affected by feeding RPL or RPLM, either top-dress or when supplemented to deficient diets. Lactation performance did not differ between AA-deficient or AA-adequate diets in response to RPL or RPLM supplementation. RPL or RPLM showed a positive linear relationship on the lactational performance of dairy cows whereas greater improvement effects were observed during early lactation. Supplementing RPL or RPLM is recommended on deficient-AA diet but not on adequate-AA diet.

L-lysine modified whey protein isolate: Mechanism on the improvement of the gel properties and its application as model fish sausage

In this study, whey protein isolate (WPI) was used as raw material to study the effects of l-lysine (Lys) on the gel properties and structure of WPI, and the application of modified WPI in fish sausage was studied. The results showed that with the increase of Lys concentration, the gel properties and water holding capacity of WPI were greatly improved, while the Lys concentration exceeding 4 mg/mL would produce adverse reactions, such as the decrease of chromaticity and gel hardness. At Lys concentration of 1.6 mg/mL, WPI showed the highest texture properties and good water holding capacity, which depended on the dense microstructure and reduced pore size. This was because WPI crosslinks with Lys through electrostatic interaction, reducing electrostatic repulsion and promoting its crosslinking and polymerization, which was manifested by the change of WPI structure and the increase of particle size. In addition, the hardness, chewiness, and cooking loss capacity of the surimi added with modified WPI were better than those of the pure fish sausage, corn starch and WPI single treatment group. This study can provide a theoretical basis for the study of WPI modified gel and provide guidance for the modified WPI used as gelling agent in surimi products.

Characterization and Antibacterial Properties of Egg White Protein Films Loaded with ε-Polylysine: Evaluation of Their Degradability and Application.

There is an ongoing trend to design new kinds of food packaging materials with excellent properties which are environmentally friendly enough. The aim of this study was to prepare and characterize egg white protein (EWP)-based composite films with and without ε-polylysine (Lys), as well as to compare their physical-chemical properties, structural properties, degradation and antibacterial properties. The results showed that with the addition of Lys, the composite films showed a decreasing tendency of the water permeability due to the enhanced interaction between proteins and water molecules. As indicated by the structural properties, stronger cross-linking and intermolecular interactions happened with increasing concentration of Lys. In addition, the composite films presented excellent antibacterial activities against Escherichia coli and Staphylococcus aureus on chilled pork in the presence of Lys. Therefore, our prepared films might be used as a freshness-keeping material with an application in meat preservation. The biodegradation evaluation demonstrated that the composite films were environmental-friendly and have potential applications in the field of food packaging.

Characterization of aspartokinase double mutants using a combination of experiments and simulations

Aspartokinase (AK) is synergistically suppressed by Thr and Lys in the Corynebacterium metabolic pathway. Site-directed mutations can significantly improve AK inhibition. Our previous studies confirmed that sites 379 and 380 were important sites affecting enzyme activity, so we further screen the double mutants with excellent enzymatic properties from sites 379 and 380, and discuss the difference of enzyme activity between the double mutants and single mutants. Here, a double mutant, T379L/A380 M, with improved enzyme activity (2.74-fold) was obtained. Enzymatic property experiments showed that the optimum temperature of T379L/A380 M increased from 26 °C (recombinant Escherichia coli; WT-AK) to 45 °C and that the optimal pH decreased from 8.0 (WT-AK) to 7.5. Further, the half-life decreased from 4.5 to 3.32 h. These enzymatic properties were better than other mutant strains. Inhibition was diminished with low concentrations of Lys, and Lys + Thr presented an activating role. Subsequently, the reasons for the improved AK enzyme activity were illustrated with microscale thermophoresis (MST) experiments and molecular dynamic (MD) simulation by measuring ligand affinity and AK conformational changes. MST showed that the affinity between T379L/A380 M and Lys decreased, but the affinity between T379L/A380 M and Asp increased, promoting T379L/A380 M enzyme activity. MD experiments showed that T379L/A380 M enhanced the Asp-ATP affinity and catalyzed the transfer of residues S192 and D193 to Asp, promoting T379L/A380 M enzyme activity. However, the mutation did not cause fluctuations in the substrate Asp and ATP pockets. This might be why the enzyme activity was inferior to that of the single mutants (T379L and A380 M).

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.

Effects of Heat-Not-Burn Cigarette Smoking on the Secretion of Saliva and Its Innate Immune System Components.

Saliva and salivary antimicrobial proteins play important roles in the innate immunity, which prevents infections of orally invading bacteria and viruses. In this study, we compared the secretion rates of salivary lactoferrin (Lac) and lysozyme (Lys) in heat-not-burn (HNB) cigarette smokers and non-smokers. The analysis population for this study included 212 members of the fire department, including 32 HNB cigarette smokers, 17 paper cigarette smokers, 14 combined HNB and paper cigarette smokers, and 149 non-smokers. Salivary Lac and Lys concentrations were assessed using enzyme immunoassay. Saliva secretion was significantly lower among HNB cigarette smokers (p < 0.01) than among non-smokers. Accompanying this result, salivary Lac and Lys secretion rates were significantly lower among smokers, particularly HNB cigarette smokers, than among non-smokers (all p < 0.01). Our findings suggest a possible adverse effect of HNB cigarette on the amount of Lac and Lys released into the oral cavity.

Standardized ileal digestible lysine requirements of 21–28 days old male broilers

The objective of this study was to estimate the standardized ileal digestible (SID) lysine (Lys) requirement for male broiler chickens at the age of 21–28 days. A total of 240 (21 days old) Ross 308 broilers (842 ± 43.9 g; mean ± SD) were allocated to six different dietary treatments in a randomized complete block design with eight replicate cages per treatment. The six experimental diets were formulated based on corn, soybean meal, and synthetic amino acids to contain dietary SID Lys equally increased from 7.5 g/kg to 12.5 g/kg, with a consistent concentration of all amino acids except for Lys. As the SID Lys increased in the experimental diet, the weight gain, feed intake, and G:F increased linearly (P < 0.05) and quadratically (P < 0.05). The Lys intake linearly (P < 0.01) increased as the SID Lys concentration increased. The SID Lys requirements for weight gain and G:F were 10.6 g/kg and 10.9 g/kg for the one-slope broken-line, 11.6 g/kg and 12.1 g/kg for the quadratic line, and 11.0 g/kg and 11.5 g/kg for 95 % of the upper asymptote of the quadratic model, respectively. In summary, the dietary SID Lys for optimum body weight gain and G:F of 21–28 days old male broilers were 10.7 g/kg and 10.9 g/kg, respectively. In addition, the SID Lys for maximum body weight gain and G:F were 11.6 g/kg and 12.1 g/kg, respectively.

Effects of Dietary Lysine Levels on Growth Performance, Nutrient Digestibility, Serum Metabolites, and Meat Quality of Baqing Pigs.

Simple SummaryThis study investigated the effects of different standardized ileal digestible (SID) Lys levels on growth performance, nutrient digestibility, serum metabolites, and carcass and meat traits of Baqing pigs. The results revealed that the addition of dietary SID Lys was beneficial for the average daily feed intake (ADFI), gain to feed ratio (G/F), and average daily gain (ADG) of Baqing pigs at the growth phase. The serum concentrations of triglycerides, lysine, and histidine increased by increasing dietary Lys levels. Compared with the treatment three group, dietary SID Lys addition content at treatment four increased the shear force of the longissimus dorsi muscle, but it did not affect the other carcass and meat traits. The SID Lys requirement of 20–40 kg, 40–60 kg, and 60–90 kg of Baqing pigs fed corn–soybean meal-based diets is estimated to be 0.92%, 0.66%, and 0.55% of the diets, respectively.This study was carried out to determine the Lys requirements of Baqing pigs and the effects of different dietary lysine levels on growth performance, apparent nutrient digestibility, serum metabolites, and carcass and meat traits. A total of 120 castrated Baqing pigs were selected by body weight and randomly assigned to five dietary treatments with six replicate pens (4 pigs per pen, castrated) per treatment in a randomized complete block design. Five diets in mash form were formulated to contain SID Lys at 0.56%, 0.68%, 0.80%, 0.92%, and 1.04% of diet in phase 1 (20–40 kg), at 0.45%, 0.54%, 0.63%, 0.72%, and 0.81% of diet in phase 2 (40–60 kg), and at 0.39%, 0.47%, 0.55%, 0.63%, and 0.71% of diet in phase 3 (60–90 kg), respectively. The results showed that the bodyweight of pigs was not affected by dietary SID Lys content during each period. However, the addition of dietary SID Lys linearly reduced F/G in the first period and quadratically increased ADG during the second period (p < 0.05). The digestible energy (DE) was increased linearly and quadratically in the first phases with the dietary increased SID Lys levels, while DE was reduced in the third and second phases (p < 0.05). Increasing SID Lys contents linearly increased the serum TG concentration and quadratically decreased the serum GLU concentration, while linearly reducing the serum HDLC concentration of first period pigs (p < 0.05). Serum concentrations of TP, TG, TC, and LDLC were increased linearly with the increasing dietary SID Lys levels in the second period (p < 0.05). The serum concentrations of Lys increased quadratically, and histidine increased linearly with the increased dietary SID Lys levels (p < 0.05). Compared with the treatment three group, dietary SID Lys addition content at treatment four increased the shear force of the longissimus dorsi muscle (p < 0.05), but it did not affect the other carcass and meat traits. The optimal SID Lys requirement of 20–40 kg, 40–60 kg, and 60–90 kg of Baqing pigs fed corn–soybean meal-based diets is estimated to be 0.92%, 0.66%, and 0.55% of the diets by the quadratic curve models, respectively.

Dynamic control of 4-hydroxyisoleucine biosynthesis by multi-biosensor in Corynebacterium glutamicum.

4-hydroxyisoleucine (4-HIL) has a potential value in treating diabetes. The α-ketoglutarate (α-KG)-dependent isoleucine dioxygenase (IDO) can catalyze the hydroxylation of L-isoleucine (Ile) to form 4-HIL by consuming O2. In our previous study, the ido gene was overexpressed in an Ile-producing Corynebacterium glutamicum strain to synthesize 4-HIL from glucose. Here, a triple-functional dynamic control system was designed to regulate the activity of IDO, the supply of α-KG, O2, and Ile and the synthesis of by-product L-lysine (Lys) for promoting 4-HIL synthesis. Firstly, the codon-optimized ido was positively regulated by seven Ile biosensors Lrp-PbrnFEN with different intensities, and the resulting seven D-NI strains produced 38.7-111.1mM 4-HIL. Then on the basis of D-NI, odhI and vgb were simultaneously regulated by three PbrnFEN with different intensities to synergistically control α-KG and O2 supply. The 4-HIL titer of twelve D-NINONV strains was more than 90mM, with D-0I7O7V generating the highest titer of 141.1 ± 15.5mM. Thirdly, ilvA was negatively regulated by an Ile attenuator PilvBNC on the basis of D-NI strains and some D-NINONV strains to balance the synthesis and conversion of Ile. The resulting D-NIPA strains produced 73.6-123.2mM 4-HIL, while D-7I7O1VPA accumulated 127.1 ± 20.2mM 4-HIL. Finally, dapA was negatively regulated by a Lys-OFF riboswitch and Lys content decreased by approximately 70% in most D-RS-NIPA strains. A strain D-RS-5IPA with the highest 4-HIL titer (177.3 ± 8.9mM) and the lowest Lys concentration (6.1 ± 0.6mM) was successfully obtained. Therefore, dynamic regulation of main and branch pathway by three functional biosensors can effectively promote 4-HIL biosynthesis in C. glutamicum. KEY POINTS: • Three biosensors were coordinated for dynamic 4-HIL biosynthesis in C. glutamicum • Bidirectional regulation of Ile synthesis and conversion promoted 4-HIL synthesis • Negative regulation of Lys synthesis further increased 4-HIL production.

Assessing Amino Acid Metabolism in Splanchnic Tissues and Mammary Glands to Short-Term Graded Removal of Lys From an Abomasal-Infused Amino Acid Mixture in Lactating Goats.

To investigate the responses of amino acid metabolism in portal-drained viscera (PDV), liver, and mammary glands (MGs) to a graded gradual decrease of post-ruminal Lys supply, four multi-catheterized lactating goats were used in a 4 × 4 Latin square experiment. Goats were fasted for 12 h and then received a 33-h abomasal infusion of an amino acid mixture and glucose. Treatments consisted of a graded decrease of Lys content in the infusate to 100 (complete), 60, 30, or 0% as in casein. Lys-removed infusions decreased the production of milk, milk protein, fat, and lactose linearly and also decreased arterial Lys concentrations linearly (p < 0.05). Net PDV uptake decreased linearly (p < 0.05) with decreasing PDV loss ratio (p < 0.05). Although liver removal of Lys decreased linearly (p < 0.05), the removal ratio relative to portal absorption changed small, which was about 10% in all four treatments. Reduced Lys supply resulted in a linear decrease in the utilization of Lys in the peripheral tissues (except mammary, p < 0.05) and the release of more Lys in MGs. Although net mammary uptake of Lys declined linearly (p < 0.05), lactating goats can partially offset the negative effect of decreased circulating Lys concentrations by increasing mammary affinity (p < 0.05) and increasing mammary blood flow (p < 0.05). Graded removal of Lys from the infusate linearly decreased mammary uptake-to-output ratios of Lys (p < 0.05) suggesting that mammary catabolism of Lys decreased. Meanwhile, the treatments linearly increased circulating concentrations of glucagon and linearly decreased prolactin (p < 0.05). In conclusion, the results of the present study indicated that there were several mechanisms used to mitigate a Lys deficiency, including reduced catabolism of Lys in PDV and peripheral tissues (including MGs) and linearly increased mammary blood flow and mammary affinity together with increased mammary uptake and U:O of branched-chain amino acids (BCAA). Given these changes, the decline in milk protein production could be attributed to the combined effect of mass action with Lys and hormonal status.

Assessment of Neurodegenerative Changes in Turkeys Fed Diets with Different Proportions of Arginine and Methionine Relative to Lysine.

Simple SummaryIt is important to take care of a properly balanced amino acid composition in the diet in order to inhibit or delay the occurrence of processes and changes related to the destruction of nervous tissue. Therefore, an attempt was made in this manuscript to evaluate the effect of different ratios of the key amino acids arginine and methionine, relative to lysine, in relation to two turkey feeding standards. The amino acid guidelines formulated by British United Turkeys (BUT) suggest higher levels of lysine (Lys) in turkey diets than those recommended by the National Research Council (NRC). In order to assess the impact of such supplementation, we analyzed the level of indicators informing the presence or degree of advancement of neurodegenerative processes in the nervous tissue (the level of acetylcholinesterase and amyloid-β; the concentration of AChE complexes with amyloid-β and Tau protein, called glycosylated acetylcholinesterase (GAChE), indicative of the destruction of neurons). The level of low-density lipoprotein receptor-related protein 1, or LRP-1, which facilitates the breakdown of toxic amyloid-β, was also assessed. In addition, the effect of different doses of these amino acids on neurodegenerative changes in DNA, especially the degree of methylation of histone proteins resulting from covalent modifications was compared between lysine and arginine residues.We postulated that the use of optimal levels and proportions of Arg and Met relative to a low or high concentration of Lys in diets for meat turkeys would reduce the occurrence of metabolic disturbances in the nervous tissue that can lead to neurodegenerative changes. The aim of the study was to determine the effect of various proportions of Lys, Arg, and Met in diets for turkeys, with a low content of Lys in accordance with NRC (Experiment 1) recommendations, and in diets with high Lys levels that are close to the recommendations of breeding companies (Experiment 2) on selected indicators of potential neurodegenerative effects in the brain and liver of turkeys. The Experiment 1 and Experiment 2 was conducted using 864 day-old turkey chicks randomly assigned to six groups, in eight replicates (6 groups × 18 birds × 8 replicates). A full description of the methodology can be found in previously published papers using the same experimental design. Indicators informing about the presence or advancement of neurodegenerative processes in the nervous tissue were determined in the brain and liver (level of: AChE, amyloid-β, GAChE, Tau protein, LRP1, and the degree of DNA methylation). It was established that in the case of both a low (National Research Council, NRC) and a high (British United Turkeys, BUT) level of Lys in the diet of turkeys, the Arg level can be reduced to 90% of the Lys level and Met to 30% of the Lys level, because this does not cause neurodegenerative changes in turkeys. Unfavorable neurodegenerative changes may appear if the Arg level is increased from 100 to 110% of the Lys level recommended by the NRC. However, due to the lack of such a relationship when Arg is increased from 100 to 110% of the Lys level recommended by BUT, at this stage of research no definitive conclusions can be drawn regarding the risk of neurodegenerative changes caused by increasing Arg in the diet of turkeys.