Lys Concentration Research Articles

The plasma free amino acid dose-response technique: A proposed methodology for determining lysine relative bioavailability of rumen-protected lysine supplements

Estimates of Lys bioavailability of rumen-protected Lys (RP-Lys) supplements are often obtained using in vitro or 2-step in situ techniques, with little to no data determining efficacy and bioavailability in vivo. The objective of this study was to further evaluate and refine the use of the plasma free AA dose-response technique as a method for determining Lys relative bioavailability of RP-Lys supplements. Thirteen dose-response Latin square studies using 87 lactating, ruminally cannulated multiparous Holstein cows (days in milk from 55 to 315 and milk yield from 12 to 62 kg/d at the start of the studies) were conducted to measure the relative bioavailability of RP-Lys supplements. Intestinal (1 study) and abomasal (12 studies) infusions of Lys ranged from 0 to 84 g/d, and experimental periods ranged from 4 to 21 d. Basal diets were formulated to be adequate in metabolizable Met, but varied in predicted metabolizable Lys (5.04 to 6.81% of metabolizable protein). One to 4 daily blood samples were taken from the coccygeal vessels for 1 to 3 consecutive days in each period. Plasma Lys concentration in cows assigned to the control treatment (0 g/d Lys) ranged from 1.83 to 5.21% of total plasma AA, whereas that from cows duodenally or abomasally infused with Lys ranged from 2.53 to 7.51% of total plasma AA. Results from studies involving more than 2 amounts of infused Lys confirmed linearity of response. The following variables were regressed against the plasma Lys dose-response slopes generated from the Lys infusion treatments to examine their effects on the magnitude of the slopes: plasma Lys concentration of the control diet, plasma Lys concentration at the greatest amount of infused Lys, net energy of lactation and metabolizable protein balances, metabolizable protein supply, days in milk, milk yield, milk concentrations of fat, true protein, and lactose, milk true protein yield, and dry matter intake. The variable having the greatest effect on the magnitude of the dose-response slope was the plasma Lys concentration at the greatest amount infused. The relative bioavailability of evaluated RP-Lys supplements using the plasma free AA dose-response technique ranged from 5 to 87%. It was concluded that plasma free Lys increases in a linear fashion to increasing amounts of absorbed Lys and that the dose-response technique is an appropriate technique for evaluating RP-Lys supplements.

Amino acid composition of rumen bacteria and protozoa in cattle

Because microbial crude protein (MCP) constitutes more than 50% of the protein digested in cattle, its AA composition is needed to adequately estimate AA supply. Our objective was to update the AA contributions of the rumen microbial AA flowing to the duodenum using only studies from cattle, differentiating between fluid-associated bacteria (FAB), particle-associated bacteria (PAB), and protozoa, based on published literature (53, 16, and 18 treatment means were used for each type of microorganism, respectively). In addition, Cys and Met reported concentrations were retained only when an adequate protection of the sulfur groups was performed before the acid hydrolysis. The total AA (or true protein) fraction represented 82.4% of CP in bacteria. For 10 AA, including 4 essential AA, the AA composition differed between protozoa and bacteria. The most noticeable differences were a 45% lower Lys concentration and 40% higher Ala concentration in bacteria than in protozoa. Differences between FAB and PAB were less pronounced than differences between bacteria and protozoa. Assuming 33% FAB, 50% PAB, and 17% of protozoa in MCP duodenal flow, the updated concentrations of AA would decrease supply estimates of Met, Thr, and Val originating from MCP and increase those of Lys and Phe by 5 to 10% compared with those calculated using the FAB composition reported previously. Therefore, inclusion of the contribution of PAB and protozoa to the duodenal MCP flow is needed to adequately estimate AA supply from microbial origin when a factorial method is used to estimate duodenal AA flow. Furthermore, acknowledging the fact that hydrolysis of 1 kg of true microbial protein yields 1.16 kg of free AA substantially increases the estimates of AA supply from MCP.

Modeling of the in vitro melanoid formation reaction on the interaction of protein hydrolysate of chicken egg and glucose

Food production technologies, including heat treatment, are often accompanied by a change in their organoleptic characteristics (color, taste and aroma) due to the formation of colored substances as a result of the melanoidin reaction. The authors simulated the reaction of melanoidin formation in vitro using the example of the interaction of the hydrolyzate of a chicken egg protein and glucose to determine the content of amino acids depending on the conditions for carrying out this reaction. The egg protein (0.2 g) was subjected to acid hydrolysis for 24 hours at 80 °C. Then the hydrolyzate was neutralized (vend=100 см3) and the initial amino acid content was determined therein. In each sample (30 см3), 4.5 g of glucose was added to the hydrolyzate to obtain a 15% solution of glucose in the hydrolyzate. The effect of temperature (50, 70 and 90 °C), time (10, 30 and 50 min), pH (pH 2, 7 and 12) on the amino acid content in the hydrolyzate as a result of the melanoidin reaction has been studied. The determination of the amount of amino acids was carried out using high performance liquid chromatography with precolumnar derivatization using o-phthalaldehyde. As a result of the studies on modeling the melanoidin reaction, the following regularities were revealed: when the temperature of the Mayyar reaction increased, the concentrations of GLU, SER, HIS, THR, ARG, ALA, CYS, VAL, MET, LEU, and LYS decreased. At the same time, with an increase in the duration of the reaction, an increase in the concentration of SER, THR, VAL, MET, ILE, LEU was observed. Variations in the concentration of amino acids in the reaction medium with increasing temperature were characteristic for ASP, GLY, TYR, PHE, ILE, and with increasing the reaction time for ASP, GLU, HIS, GLY, ARG, ALA, TYR, CYS, PHE, LYS. Other things being equal, the process of melanoid formation most fully proceeded in an alkaline medium at pH 12. Thus, the study of the effect of the experimental conditions showed that during the melanoidin formation, the content of certain amino acids (including essential amino acids) decreases and, consequently, the nutritional value of the product decreases. As a result of this reaction, from 20 to 50% of free amino acids are lost, and with increasing temperature and increasing the duration of heating, these losses increase. The obtained data are important to take into account when developing new food technologies with the maximum preservation of their chemical composition, nutritional value and consumer properties.

Effects of graded removal of lysine from an intravenously infused amino acid mixture on lactation performance and mammary amino acid metabolism in lactating goats

To investigate responses of milk protein synthesis and mammary AA metabolism to a graded decrease of postruminal Lys supply, 4 lactating goats fitted with jugular vein, mammary vein, and carotid artery catheters and transonic blood flow detectors on the external pudic artery were used in a 4 × 4 Latin square experiment. Goats were fasted for 24 h and then received a 9-h intravenous infusion of an AA mixture plus glucose. Milk yield was recorded and samples were taken in h 2 to 8 of the infusion period; a mammary biopsy was performed in the last hour. Treatments were graded decrease of lysine content in the infusate to 100 (complete), 60, 30, or 0% as in casein. Lysine-removed infusions linearly decreased milk yield, tended to decrease lactose yield, and tended to increase milk fat to protein ratio. Milk protein content and yield were linearly decreased by graded Lys deficiency. Mammary Lys uptake was concomitantly decreased, but linear regression analysis found no significant relationship between mammary Lys uptake and milk protein yield. Treatments had no effects on phosphorylation levels of the downstream proteins measured in the mammalian target or rapamycin pathway except for a tended quadratic effect on that of eukaryotic initiation factor 2, which was increased and then decreased by graded Lys deficiency. Removal of Lys from the infusate linearly increased circulating glucagon and glucose. Removal of Lys from the infusate linearly decreased arterial and venous concentrations of Lys. Treatments also had a significant quadratic effect on venous Lys, suggesting mechanisms to stabilize circulating Lys at a certain range. The 2 infusions partially removing Lys resulted in a similar 20% decrease, whereas the 0% Lys infusion resulted in an abrupt 70% decrease in mammary Lys uptake compared with that of the full-AA mixture infusion. Consistent with the abrupt decrease, mammary Lys uptake-to-output ratio decreased from 2.2 to 0.92, suggesting catabolism of Lys in the mammary gland could be completely prevented when the animal faced severe Lys deficiency. Mammary blood flow was linearly increased, consistent with the linearly increased circulating nitric oxide by graded Lys deficiency, indicating mechanisms to ensure the priority of the mammary gland in acquiring AA for milk protein synthesis. Infusions with Lys removed increased mammary clearance rate of Lys numerically by 2 to 3 fold. In conclusion, the decreased milk protein yield by graded Lys deficiency was mainly a result of the varied physiological status, as indicated by the elevated circulating glucagon and glucose, rather than a result of the decreased mammary Lys uptake or depressed signals in the mTOR pathway. Mechanisms of Lys deficiency to promote glucagon secretion and mammary blood flow and glucagon to depress milk protein synthesis need to be clarified by future studies.

Effects of dietary lysine supplementation on performance, egg quality, and development of reproductive system in egg-laying ducks

ABSTRACTThis study was conducted to examine five lysine (Lys) levels (0.75, 0.80, 0.85, 0.90, and 0.95%) to estimate the optimal level of Lys for Longyan laying ducks from 22 to 38 wk of age. Nine hundred Longyan ducks aged 22 wk were assigned randomly to the 5 dietary treatments, where each treatment comprised 6 replicate pens with 30 ducks per pen. Lys had no effects on egg production, egg mass, feed conversion ratio, shape index, Haugh unit, yolk colour, yolk weight, or albumen weight, but the egg weight was improved significantly (P < 0.05) by dietary Lys supplementation, whereas the eggshell thickness, eggshell weight, and eggshell proportion decreased significantly as the Lys levels increased. Dietary supplementation of Lys did not affect the reproductive organ indices or the plasma levels of estradiol, luteinizing hormone, or follicle-stimulating hormone, whereas the plasma level of progesterone declined significantly (P < 0.01) as elevation the concentrations of Lys in the diets. In conclusion, the results indicate that the optimal Lys level in Longyan laying ducks diets is 0.80% to produce eggs with normal egg weight without adverse effects on the eggshell weight, eggshell proportion, or eggshell thickness.

Exercise increases lactoferrin, but decreases lysozyme in salivary granulocytes.

Intracellular lactoferrin (Lac) and lysozyme (Lys) content play an important role in regulating inflammation and promoting host protection. While exercise has demonstrated an increase in Lac and Lys concentration in exocrine solutions, little is known regarding intracellular concentration changes in response to exercise. To quantify intracellular Lac and Lys concentration before and after exercise in salivary CD45+CD15+ cells. 11 males (20.3 ± 0.8years, 57.2 ± 7.6 mL/kg/min V̇O2pk, 11.1 ± 3.9% body fat) ran for 45min at 75% of VO2pk. 12mL of stimulated saliva were collected pre and immediately post exercise. Saliva was filtered through a 30-µm filter before analysis of leukocytes (CD45+) and granulocytes (CD45+CD15+) using flow cytometry. Median fluorescent intensity (MFI) of Lac increased from pre (64,268 ± 46,036 MFI) to post (117,134 ± 88,115 MFI) exercise (p <0.05). Lys MFI decreased with exercise (pre: 16,933 ± 8249; post: 11,616 ± 6875) (p <0.05). Acute running resulted in an increased Lac concentration which could lead to a decrease in inflammation, adding further evidence of the anti-inflammatory effects of exercise. Conversely, the exercise-associated decrease of intracellular Lys content could be the cause of increased Lys in exocrine solutions.

Changes of serum free amino acids in eventing horses at rest and during exercise in response to dietary protein

Although there are published expertise about serum free amino acids, to the knowledge of the authors no data were reported on eventing horses. In this way, it is important to study the concentration of dietary protein and serum free amino acid during exercise in order to improve nutritional strategies. The aim of this study was to investigate the concentration of the serum free lysine (Lys), threonine (Thr), leucine (Leu), isoleucine (Ile) and valine (Val) of eventing horses fed diets with different levels of protein at before and during exercise. Twenty-four Brazilian Sport Horses trained for eventing were used in a randomized block design with 4 diets (7.5%, 9.0%, 11.0% and 13.0% of CP) and 6 repetitions (horses). Horses were blocked according to their experience in competitions. The test protocol consisted of a warm up of walking and trotting and then a gallop starting at 6.0 m/s with increases in speed of 1 m/s every minute up to 10 m/s. Venous blood samples were collected before the test and during exercise. Concentration of Lys, Thr, Leu, Ile and Val from diets and serum free amino acids were determined by HPLC analysis. Total intake values of Lys, Thr, Leu, Ile and Val were affected by dietary protein levels. Differences on the serum free concentrations of Lys, Leu, Ile and Val as a function of the sampling time were observed. The Lys requirement for athletic horses appear to be lower than what is currently proposed. Moreover, the effect of exercise on serum free Lys, Leu, Ile and Val concentration, may be interpreted as an indicator of these amino acids metabolic response.

Effects of feeding betaine-containing liquid supplement to transition dairy cows

Betaine is a natural compound found in sugar beets that serves as a methyl donor and organic osmolyte when fed to animals. The objective was to evaluate the effect of feeding betaine-containing molasses on performance of transition dairy cows during late summer in 2 trials. In early September, cows were randomly assigned to betaine (BET) or control (CON) groups either shortly after dry off (trial 1; n = 10 per treatment) or 24 d before calving (trial 2; n = 8 per treatment) based on parity and previous mature equivalent milk yield. Cows were fed common diets supplemented either with a liquid supplement made of molasses from sugar cane and condensed beet solubles containing betaine [BET, 89.1 g/kg of dry matter (DM)] or a sugar cane molasses-based liquid supplement without betaine (CON) until 8 wk postpartum. The liquid supplements had similar nutrient contents and were fed at a rate of 1.1 and 1.4 kg DM/d for pre- and postpartum cows, respectively. Starting at their entry in the studies, cows were housed in the same freestall barn without a cooling system. After calving, all cows were housed in the same barn cooled by misters and fans and milked thrice daily. Intake was recorded daily and body weight and body condition score were assessed every 2 wk. Milk yield was recorded at each milking and composition was analyzed weekly. Blood samples were collected weekly from a subset of cows to assess concentrations of metabolites and AA. No treatment effects were apparent for DM intake and body weight in the prepartum and postpartum periods. For cows enrolled at dry off, BET supported higher milk yield (45.1 vs. 41.9 kg/d) and fat content (4.78 vs. 4.34%) and elevated plasma concentrations of nonesterified fatty acids and β-hydroxybutyrate in early lactation compared to CON. However, no differences were observed for milk yield, most milk component contents and yields, and blood metabolites between treatments for cows enrolled during the close-up period. Compared to cows in the CON group, BET cows enrolled during the far-off period tended to have lower plasma concentrations of Met, Thr, and Trp during the pre- and postpartum periods. They also had lower plasma concentrations of Lys and Phe before calving but higher plasma Gly concentration after parturition. In conclusion, feeding a betaine-containing liquid supplement from far-off through early lactation improves lactation performance but increases adipose tissue mobilization and production of ketone bodies in early lactation.

Modelling of lysine requirement in broiler breeder hens based on daily nitrogen retention and efficiency of dietary lysine utilization

The current feeding programs used for broiler breeder hens need information on how to make use of the genetic potential more efficiently by modelling the amino acid (AA) requirements. Thus, this study aimed to determine the model parameters for maximum nitrogen retention (NRmaxT), nitrogen maintenance requirement (NMR) and the efficiency of lysine utilization (bc−1) to determine the lysine (Lys) requirements of broiler breeder hens. Nitrogen balance trials were performed in two periods (I: 31–35 wks and II: 46–50 wks). Seven dietary treatments were used with eight replicates and one hen per cage; the treatments consisted of seven diets with protein levels ranging from 58.8 to 311.9g/kg of feed, with Lys being limiting in the dietary protein (c=3.91g of Lys in 100g of CP). For each period, nitrogen intake (NI), nitrogen excretion (NEX), nitrogen in egg mass (NEM), nitrogen deposition (ND) and nitrogen retention (NR, NR=ND+NEM+NMR) were obtained in a N balance trial of 25days. The NMR was calculated as the intersection point of the exponential curve between NEX and NI at NI=0. The NRmaxT and b (slope related to protein quality) were estimated by the exponential fit between NR and NI. The Lys efficiency bc−1 was obtained dividing b by c. The likelihood ratio test for the model parameters yielded 255mg/BWkg0.67 for NMR, 0.000117 for b and 1684mg/BWkg0.67 (period I) and 1484mg/BWkg0.67 (period II) for NRmaxT. The necessary Lys intake dependent on NR and Lys efficiency was derived by the equation Lys=(lnNRmaxT-ln(NRmaxT-NR))/(16×bc−1). Lys intakes required to achieve 0.80 times the maximum potential (NRmaxT) were 915mg and 876mg in the period I and II, respectively. For broiler breeder hens, assuming 0.80 times the NRmaxT value and average efficiency of Lys utilization, 6.02g/kg (31–35 wk) and 5.96g/kg (46–50 wk) digestible dietary Lys were observed as optimal digestible Lys concentration in the diet (corresponding to 152 and 147g of daily feed intake, respectively). Results of model calculations need verification in performance trials with evaluation of nitrogen deposition and varying dietary Lys efficiencies.

Impact of improving dietary amino acid balance for lactating sows on efficiency of dietary amino acid utilization and transcript abundance of genes encoding lysine transporters in mammary tissue.

Lactating multiparous Yorkshire sows ( = 64) were used in 2 experiments to test the hypothesis that reducing dietary CP intake and improving AA balance through crystalline AA (CAA) supplementation improves apparent dietary AA utilization efficiency for milk production and increases transcript abundance of genes encoding Lys transporter proteins in mammary tissue. In Exp. 1, 40 sows were assigned to 1 of 4 diets: 1) high CP (HCP; 16.0% CP, as-fed basis; analyzed concentration), 2) medium-high CP (MHCP; 15.7% CP), 3) medium-low CP (MLCP; 14.3% CP), and 4) low CP (LCP; 13.2% CP). The HCP diet was formulated using soybean meal and corn as the only Lys sources. The reduced-CP diets contained CAA to meet estimated requirements for essential AA that became progressively limiting with reduction in CP concentration, that is, Lys, Ile, Met + Cys, Thr, Trp, and Val. Dietary standardized ileal digestible (SID) Lys concentration was 80% of the estimated requirement. In Exp. 2, 24 sows were assigned to the HCP or LCP diets. In Exp. 1, blood samples were postprandially collected 15 h on d 3, 7, 14, and 18 of lactation and utilization efficiency of dietary AA for milk production was calculated during early (d 3 to 7) and peak (d 14 to 18) lactation. Efficiency values were estimated from daily SID AA intakes and milk AA yield, with corrections for maternal AA requirement for maintenance and AA contribution from body protein losses. In Exp. 2, mammary tissue was biopsied on d 4 and 14 of lactation to determine the mRNA abundance of genes encoding Lys transporter proteins. In peak lactation, Lys, Thr, Trp, and Val utilization efficiency increased with decreasing dietary CP (linear for Trp and Val, < 0.05; in sows fed the MHCP diet vs. sows fed the HCP diet for Lys and Thr, < 0.05). Total essential and nonessential 15-h postprandial serum AA concentrations increased with decreasing dietary CP (linear, = 0.09 and < 0.05, respectively), suggesting increased maternal body protein mobilization. Transcript abundance of several genes involved in Lys transport in mammary tissue did not differ between sows fed the LCP and HCP diets. Feeding lactating sows low-CP diets supplemented with CAA increases the efficiency of utilizing dietary Lys, Thr, Trp, and Val for milk protein production but is unrelated to abundance in mRNA of genes encoding Lys transport proteins in the mammary gland. Dietary Lys utilization for milk protein production in lactating sows appears to be optimized when crystalline Lys is included at a minimum of 0.10% in a diet containing 15.70% CP.

Mobility of lysozyme in poly(l-lysine)/hyaluronic acid multilayer films

The spatial and temporal control over presentation of protein-based biomolecules such as growth factors and hormones is crucial for in vitro applications to mimic the complex in vivo environment. We investigated the interaction of a model protein lysozyme (Lys) with poly(L-lysine)/hyaluronic acid (PLL/HA) multilayer films. We focused on Lys diffusion as well as adsorption and retention within the film as a function of the film deposition conditions and post-treatment. Additionally, an effect of Lys concentration on its mobility was probed. A combination of confocal fluorescence microscopy, fluorescence recovery after photobleaching, and microfluidics was employed for this investigation. Our main finding is that adsorption of PLL and HA after protein loading induces acceleration and reduction of Lys mobility, respectively. These results suggest that a charge balance in the film to a high extent governs the protein–film interaction. We believe that control over protein mobility is a key to reach the full potential of the PLL/HA films as reservoirs for biomolecules depending on the application demand.

A label-free multi-functionalized electrochemical aptasensor based on a Fe3O4@3D-rGO@plasma-polymerized (4-vinyl pyridine) nanocomposite for the sensitive detection of proteins in whole blood

In this paper, we report a novel label-free electrochemical aptasensor for detecting proteins in whole blood based on a three-component nanocomposite, in which ferriferrous oxide and three-dimensional graphene nanocomposite were modified with the plasma-polymerized 4-vinyl pyridine (Fe3O4@3D-rGO@PP4VP). In this novel sensing strategy, large amounts of amino groups in PP4VP facilitated the immobilization of aptamer strands via the strong electrostatic interaction between positively charged ammonium groups of the nanocomposites and negatively charged phosphate groups of aptamers. In the presence of thrombin, LYS (LYS), and platelet-derived growth factor-BB (PDGF-BB), the adsorbed aptamer strands on the developed nanocomposite surface caught the targeted proteins at the electrode interface. The aptamer preferred to be a barrier for electrons and inhibited electron transfer, leading to the decreased peak current of cyclic voltammetry measurements and the increased electron transfer resistance of electrochemical impedance spectroscopy. The determination of the thrombin, PDGF-BB, and LYS concentrations with this novel strategy showed low detection limits of 4.5, 29.4, and 14pg·mL−1, and the analytical ranges extend from 0.01 to 50, 0.1 to 100, and 0.1 to 200ng·mL−1, respectively. The resultant aptasensor exhibited high selectivity, acceptable reproducibility, and stability toward thrombin. The aptasensor could be used to detect thrombin in whole blood samples, thereby suggesting its possible application in clinical settings.

Assessment of the effect of methionine supplementation and inclusion of hydrolyzed wheat protein in milk protein-based milk replacers on the performance of intensively fed Holstein calves

The objectives of this study were to compare 2 milk replacers containing only milk proteins with or without supplemental Met, and to compare a milk replacer containing hydrolyzed wheat protein at 4.5% of dry matter (DM) and supplemental Lys and Met against the 2 all-milk-protein formulas, by assessing their effect on the growth performance, efficiency, and plasma urea nitrogen of pre-weaning Holstein calves. Thus, 57 Holstein calves were allotted to the following 3 treatments: (1) a skim milk plus whey protein concentrate-based milk replacer (SMWP) containing about 2.6% Lys and 0.6% Met on a DM basis; (2) SMWP + M based on skim milk and whey proteins, containing about 2.6% Lys, and supplemental Met to reach 0.9% on a DM basis; and (3) a skim milk plus whey protein concentrate plus 4.5% of the DM as hydrolyzed wheat protein based milk replacer (HWP + LM) where the wheat protein replaced 50% of the whey protein concentrate, and also contained supplemental Lys and Met to match the profile of SMWP + M (i.e., Lys 2.6 and Met 0.9% on DM basis). No difference in any of the responses was observed by supplementing the milk protein based formula with Met or when hydrolyzed wheat protein was added to the formula. Results indicate that (1) a milk replacer based on skim milk protein and whey protein with a Lys concentration of ~2.6% does not benefit from Met supplementation, and (2) milk replacer containing 4.5% of the DM as hydrolyzed wheat protein and supplemented with Lys and Met can support the same growth performance as milk protein-based formulas.

Standardized ileal digestible lysine requirements of male pigs immunized against gonadotrophin releasing factor.

An experiment was conducted to determine the standardized ileal digestible (SID) Lys requirement of entire male and male pigs immunized against gonadotrophin releasing factor (GnRF; immunocastrates). A total of 420 entire male and immunocastrated (IC) male pigs weighing 60.1 kg BW (SEM 0.49) were used in a 2 × 5 factorial experiment with the main effects being gender (entire males or IC males) and 5 concentrations of SID Lys:DE ratio (0.32, 0.43, 0.54, 0.64, or 0.75 g SID Lys/MJ DE). The diets were fed for 6 wk until slaughter at 107.5 kg BW (SEM 5.72). Over the entire period, IC males had a greater ADG ( < 0.001), greater ADFI ( < 0.001), and lower G:F ( < 0.001) compared with entire males. Immunocastrated males had increased plasma urea nitrogen (PUN) concentrations compared with entire males from d 10 to 42 ( < 0.001 for all days). Plasma urea nitrogen concentration also increased as Lys concentrations increased from d 3 to 42 ( < 0.001 for all days). Using the linear-plateau model, the optimal ADG for entire males was achieved at SID Lys concentrations of 0.68, 0.62, 0.54, and 0.58 g/MJ DE whereas optimal G:F was achieved at SID Lys concentrations of 0.72, 0.60, 0.54, and 0.51 g/MJ DE for the time periods d 0 to 14, d 15 to 28, d 29 to 42, and d 0 to 42, respectively. For IC males, optimal ADG was achieved at SID Lys concentrations of 0.64, 0.43, 0.38, and 0.40 g/MJ DE whereas optimal G:F was achieved at SID Lys concentrations of 0.64, 0.43, 0.36, and 0.42 g/MJ DE for the same respective time periods. Using the quadratic polynomial model, maximum ADG for entire males was achieved at SID Lys concentrations of 0.62 and 0.58 g/MJ DE whereas maximum G:F was achieved at SID Lys concentrations of 0.59 and 0.68 g/MJ DE for d 29 to 42 and d 0 to 42, respectively. For IC pigs, maximum ADG was achieved at SID Lys concentrations of 0.69, 0.54, and 0.64 g/MJ DE whereas maximum G:F was achieved at SID Lys concentrations of 0.81, 0.54, and 0.64 g/MJ DE for d 0 to 14, d 29 to 42, and d 0 to 42, respectively. A solution could not be found using the quadratic polynomial model for entire males for d 0 to 14 for both ADG and G:F and for both entire males and IC males for d 15 to 28 within the range of Lys values tested. When both the growth performance and PUN values are considered, the results suggest that IC males show a response to dietary SID Lys similar to that of entire males for 2 wk after the second immunization against GnRF. After this, IC males have a lower requirement for SID Lys than entire males.

Body composition, tissue deposition, and lysine utilization for protein deposition of barrows and gilts fed crystalline or protein-bound lysine.

An experiment with 2 trials (28 d/trial) was conducted to determine body composition, tissue deposition, and utilization of Lys for protein deposition (PD) of barrows and gilts fed -Lys·HCl (CLys) or protein-bound Lys in soybean meal (SBM). Thirty-two growing pigs (16 barrows and 16 gilts; average initial BW of 18.6 kg) were used in each of 2 trials. Four pigs (2 barrows and 2 gilts) were euthanized at the start of each trial to determine initial body composition. The remaining pigs were euthanized at the end of the trials to determine empty-body composition and deposition rates of water, protein, fat, ash, and AA. Pigs were randomly allotted to 1 of 7 dietary treatments. There were 2 replications per treatment in each trial for a total of 4 replications. Dietary treatments consisted of a corn-SBM basal diet (0.48% Lys) and diets containing 0.56%, 0.65%, and 0.74% standardized ileal digestible (SID) Lys that were achieved by adding Lys to the basal diet from either SBM or CLys. Pigs fed the CLys-supplemented diets at 0.65% SID Lys had more ( < 0.05) body water (663 vs. 624 g/kg) and less ( < 0.01) body protein (153 vs. 160 g/kg) than pigs fed the SBM-supplemented diets. Body fat content decreased ( < 0.01) as the dietary Lys increased similarly for pigs fed Lys from SBM and pigs fed CLys. Gilts had greater ( = 0.05) body Lys content in body protein than barrows (7.68 vs. 7.52 g/100 g). Empty-body ash contents were not different between pigs fed CLys or SBM-supplemented diets. Water deposition and PD increased linearly ( < 0.01) with dietary Lys and were least ( < 0.01) in pigs fed the basal diet but were similar when comparing pigs fed CLys and SBM-supplemented diets at the same dietary Lys concentration. Lysine deposition showed a linear increase ( < 0.01) with dietary Lys but was not different between pigs fed the 2 Lys sources at the same concentration. Barrows and gilts did not differ in tissue deposition rates. Overall, empty-body contents and deposition rates of essential and nonessential AA were not different between pigs fed CLys and pigs fed SBM-bound Lys. The amount of SID Lys required for PD ranged between 0.09 and 0.13 g/g for both sources of Lys. The Lys deposition:SID Lys intake ratio was greater ( < 0.01) in gilts than barrows (0.62 vs. 0.56). Body composition, tissue deposition, and utilization of Lys for PD and Lys deposition were not different in pigs fed diets supplemented with -Lys·HCl with respect to protein-bound Lys in SBM.

Dietary levels of protein and free amino acids affect pancreatic proteases activities, amino acids transporters expression and serum amino acid concentrations in starter pigs.

The dietary contents of crude protein and free amino acids (AA) may affect the protein digestion and AA absorption in pigs. Trypsin and chymotrypsin activities, AA serum concentrations and expression of AA transporters in the small intestine of pigs fed a low protein, AA-supplemented (19.2%, LPAA) or a high protein (28.1%, HP), wheat-soybean meal diet were measured in two 14-d trials. The LPAA diet contained free L-Lys, L-Thr, DL-Met, L-Leu, L-Ile, L-Val, L-His, L-Trp and L-Phe. All pigs were fed the same amount of feed (890 and 800g/d for trial 1 and 2 respectively). In trial 1, samples of mucosa (duodenum, jejunum and ileum) and digesta (duodenum and jejunum) were collected from 14 pigs (17.2±0.4kg); in trial 2, blood samples were collected from 12 pigs (12.7±0.3kg). The trypsin and chymotrypsin activities in both intestinal segments were higher in pigs fed the HP diet (p<0.01). Trypsin activity was higher in jejunum than in duodenum regardless the dietary treatment (p<0.05). Pigs fed the LPAA diet expressed more b0,+ AT in duodenum, B0 AT1 in ileum (p<0.05), and tended to express more y+ LAT1 in duodenum (p=0.10). In pigs fed the LPAA diet, the expression of b0,+ AT was higher in duodenum than in jejunum and ileum (p<0.01), but no difference was observed in pigs fed the HP diet. Ileum had the lowest b0,+ AT expression regardless the diet. The serum concentrations of Lys, Thr and Met were higher in LPAA pigs while serum Arg was higher in HP pigs (p<0.05). Serum concentrations of AA appear to reflect the AA absorption. In conclusion, these data indicate that the dietary protein contents affect the extent of protein digestion and that supplemental free AA may influence the intestinal site of AA release and absorption, which may impact their availability for growth of young pigs.

Efficiency of lysine utilization by growing steers.

This study evaluated the efficiency of Lys utilization by growing steers. Five ruminally cannulated Holstein steers (165 ± 8 kg) housed in metabolism crates were used in a 6 × 6 Latin square design; data from a sixth steer was excluded due to erratic feed intake. All steers were limit fed (2.46 kg DM/d), twice daily, diets low in RUP (81% soybean hulls, 8% wheat straw, 6% cane molasses, and 5% vitamins and minerals). Treatments were 0, 3, 6, 9, 12, and 15 g/d of Lys continuously abomasally infused. To prevent AA other than Lys from limiting performance, a mixture providing all essential AA to excess was continuously abomasally infused. Additional continuous infusions included 10 g urea/d, 200 g acetic acid/d, 200 g propionic acid/d, and 50 g butyric acid/d to the rumen and 300 g glucose/d to the abomasum. These infusions provided adequate ruminal ammonia and increased energy supply without increasing microbial protein supply. Each 6-d period included 2 d for adaptation and 4 d for total fecal and urinary collections for measuring N balance. Blood was collected on d 6 (10 h after feeding). Diet OM digestibility was not altered ( ≥ 0.66) by treatment and averaged 73.7%. Urinary N excretion was decreased from 32.3 to 24.3 g/d by increasing Lys supplementation to 9 g/d, with no further reduction when more than 9 g/d of Lys was supplied (linear and quadratic, < 0.01). Changes in total urinary N excretion predominantly were due to changes in urinary urea N. Increasing Lys supply from 0 to 9 g/d increased N retention from 21.4 to 30.7 g/d, with no further increase beyond 9 g/d of Lys (linear and quadratic, < 0.01). Break-point analysis estimated maximal N retention at 9 g/d supplemental Lys. Over the linear response surface of 0 to 9 g/d Lys, the efficiency of Lys utilization for protein deposition was 40%. Plasma urea N tended to be linearly decreased ( = 0.06) by Lys supplementation in agreement with the reduction in urinary urea N excretion. Plasma concentrations of Lys linearly increased ( < 0.001), but Leu, Ser, Val, and Tyr ( ≤ 0.02) were linearly reduced by Lys supplementation, likely reflecting increased uptake for protein deposition. In our model, Lys supplementation promoted significant increases in N retention and was maximized at 9 g/d supplemental Lys with an efficiency of utilization of 40%.

Metabolic response to an inflammatory challenge in pigs divergently selected for residual feed intake.

Selection for residual feed intake (RFI), which is used to select animals for feed efficiency, also influences nutrient partitioning between growth and maintenance functions. This study was designed to investigate if selection for reduced RFI can alter the trade-off between growth and immunity and contributes to differences in metabolic responses to an inflammatory challenge. Piglets from 2 lines divergently selected on RFI (low: RFI, = 10, and high: RFI, = 11) were challenged at 55 d of age (on d 0) with complete Freund's adjuvant (CFA) to induce a noninfectious pneumonia. Plasma haptoglobin and nutrient concentrations (in fasted state and 2 h after feeding) were determined from d -1 to d 7, and tissue protein metabolism was determined on d 8. Haptoglobin concentrations were greater from d 1 to d 7 relative to d -1 ( < 0.01). Feed intake was less on d 1 than on the other days ( < 0.001), as was total AA plasma concentrations at fasted state ( < 0.05). Fasted concentrations of His ( = 0.06) and Trp ( = 0.05) tended to be less, those of Val were less ( < 0.05), and fed concentrations of Lys were increased ( < 0.05) on d 7 compared to d -1. Uremia was less on d 7 than on d -1 at fasted state ( < 0.05), whereas it did not vary at fed state ( 0.1). Fasted glucose and insulin plasma concentrations were stable across days ( 0.1). In the fed state and in only RFI pigs, glucose concentration was greater on d 1 than on d 3, 5, and 7 ( < 0.05). Total AA, Gln, Ile, Leu, Pro ( < 0.05), and hydroxyproline ( = 0.07) were less in RFI than RFI pigs at fed state, whereas Ala and Gly were less in RFI pigs at fasted and fed states ( < 0.05). Citrulline ( < 0.05) and Met ( < 0.01) concentrations were greater in RFI than RFI pigs in the fasted state, whereas Asp was greater in RFI pigs in both fasted and fed states ( < 0.05). On d 8, liver and LM protein synthesis tended to be lower ( = 0.07 and 0.09, respectively) and liver calpain activity was greater ( = 0.07) in RFI than RFI pigs. Liver and LM proteasome did not differ between lines ( 0.1). The metabolic differences between lines were not associated with differences in feed intake, ADG between d -1 and d 8, and haptoglobin concentration ( 0.1). Thus, it seems that that, using different metabolic strategies, both lines coped similarly with the CFA challenge. Contrary to our hypothesis, this experiment showed, in young pigs, no advantage of RFI animals in response to an inflammatory challenge.

Nutritional Value and Seasonal Availability of Feed Ingredients for Pigs in Uganda

Abstract In this study nutritional values and seasonal availability of 43 local feed ingredients for pigs in Uganda, were estimated based on nutrient analyses and literature values, information needed to develop low-cost balanced rations for pigs on smallholder farms. Parameters considered were: concentration of ash, neutral detergent fibre (NDF), crude protein (CP), calcium (Ca), phosphorous (P), ether extract (EE), total lysine (Lys), standardized ileal digestible (SID) Lys, standardized total tract digestible (STTD) P (all as % of dry matter [DM]); digestible energy (DE), (kcal kg−1 of DM); and DM concentration. Concentration of DE, total Lys, SID Lys, and STTD P were estimated. Ingredient seasonal availability and relative importance were identified. Ground sun-dried fish (Rastrineobola argentea) had highest estimated DE concentration and Napier grass (Pennisetum purpureum) had lowest (4209 and 535 kcal kg−1 of DM, respectively). Ground sun-dried fish had highest CP and estimated total Lys concentration (59.9 and 6.7% of DM, respectively) and banana peel (Musa sapientum), had lowest (5.21 and 0.08% of DM, respectively). Milled ingredients sampled here had higher ash than in the literature (e.g. ground sun-dried fish 58.1 vs 15.9% of DM) likely indicating sand contamination. There were 3 seasons of availability of ingredients. Banana peel, maize bran, and sweet potato vine (Ipomoea batatas) were ranked highest; and commercially-prepared ration, and kale/collard greens (Brassica oleracea var. acephala), were ranked lowest as potential feed ingredients. Ingredients with nutritional profiles suitable for pigs are available but some only in certain seasons. Estimated nutritional values may assist in ration formulation.

Interaction of dietary energy and protein on growth performance, carcass characteristics and digestibility in finishing barrows when fed at a constant digestible lysine to metabolizable energy ratio

The objective of this study was to determine the performance response to changes in dietary fat, protein, and fiber content in finishing barrows while maintaining a constant apparent ileal digestible (AID) Lys to metabolizable energy (ME) ratio (AID Lys:ME). The experiment was conducted in 2 trials, each containing 25 individually penned pigs. In both trials, barrows (initial wt=85.3kg) were blocked by weight and assigned to one of five experimental diets (0.40, 0.44, 0.48, 0.52, and 0.56% digestible Lys) with a constant AID Lys:ME (1.44g/MCal). Lysine content was changed by altering the proportions of corn and soybean meal and energy was altered by the addition or removal of cellulose and fat. Diets contained 0.2% titanium dioxide as a digestibility marker. Pigs were fed experimental diets for 28d, and body weights, feed intakes, and ultrasound measurements of tenth rib backfat (BF) and loin eye area (LEA) were recorded on d 14 and 28. Blood samples were taken on d 28 to determine serum urea nitrogen (SUN), insulin, T3, and T4. A quadratic effect of increasing dietary Lys was seen on ADG on d 28 showing that the addition of Lys increased gain (P<0.01). Additionally, feed efficiency, energy intake, and Lys intake increased linearly as dietary Lys concentration increased from 0.40% to 0.56% AID Lys (P<0.01). Levels of T3 increased with increasing Lys (P<0.01), but there was no effect of diet on SUN, T4, or insulin. Ultrasound estimates of BF and LEA tended to increase linearly and quadratically, respectively, as dietary Lys increased (P<0.10). Digestibility of energy, protein, NDF, and hemicellulose increased linearly in pigs fed 0.40–0.56% AID Lys (P<0.05). These results demonstrate that formulating diets to meet the recommended AID Lys:ME is not sufficient to ensure optimal growth. Therefore, the concentration of protein and energy of the diet must be individually evaluated and corrected to obtain optimal growth and efficiency.