Supplemental Lys Research Articles

L-Lysine supplementation affects dietary protein quality and growth and serum amino acid concentrations in rats

Single amino acid (AA) supplementations in foods are increasing, however their potential nutritional and physiological impacts are not fully understood. This study examined the effects of l-lysine (Lys) supplementation on protein quality of diets, serum AA concentrations and associations between the ratio of supplemental Lys to dietary protein (X) with body weight gain (BWG) in Sprague–Dawley male rats. Rats were fed one of 10 diets containing either 7% or 20% casein and supplemented with 0% (Control), 1.5%, 3%, 6% Lys or 6% Lys + 3% l-arginine (Arg) (8 rats/diet group) for 1 week. Lys supplementation reduced the protein quality of the casein-based diets (p < 0.01). BWG was reduced by supplemental Lys when X > 0.18. Free Lys supplementation dose-dependently increased serum Lys levels (p < 0.01), while increased protein-bound Lys (1.4% vs 0.52%) had little effect on serum Lys (p > 0.05). In the 7% casein diets, ≥ 1.5% supplemental Lys reduced serum alanine, asparagine, glycine, isoleucine, leucine, serine, tyrosine, valine, carnitine, ornithine, and increased urea. Supplementation of ≥ 3% Lys additionally reduced tryptophan and increased histidine, methionine and α-aminoadipic acid (α-AAA) compared to the Control (p < 0.05). In the 20% casein diets, addition of ≥ 1.5% Lys reduced serum asparagine and threonine, and ≥ 3% Lys reduced leucine, proline, tryptophan, valine, and ornithine, and 6% Lys reduced carnitine, and increased histidine, methionine, and α-AAA. Overall, this study showed that free Lys supplementation in a Lys-sufficient diet reduced the protein quality of the diets and modified the serum concentrations of many amino acids. Excess free Lys intake adversely affected growth and utilization of nutrients due to AA imbalance or antagonism. Overall lower protein intake increases susceptibility to the adverse effects of Lys supplementation.

Effects of feeding different forms of lysine supplements on lactational performance and nitrogen utilization by mid- to late-lactation dairy cows

We investigated the lactational performance and N utilization of dairy cows fed different forms of Lys supplements with the main focus on Lys derivatives of N -acetyl- l -Lys (NALL) during mid to late lactation. Forty lactating Holstein dairy cows (151 ± 78.0 DIM) were assigned to 1 of 4 treatments (n = 10) in a randomized complete block design. The 4 dietary treatments were as follows: (1) TMR without Lys supplementation (control), (2) TMR with N ε-acetyl- l -Lys supplementation at 51.5 g/d (εNALLT), (3) TMR with N α, ε-acetyl- l -Lys supplementation at 63 g/d (diNALLT), and (4) TMR with commercial rumen-protected Lys (AjiPro-L, Ajinomoto Heartland Inc.) supplementation at 100 g/d (CRPLT). Feeding of diNALLT and the CRPLT decreased DMI. Milk yield, component yield, and component concentrations were not affected by Lys supplementation. In contrast, feed conversion efficiency (milk yield/DMI) was greatest for diNALLT. The efficiencies of 3.5% FCM yield/DMI and ECM yield/DMI did not differ among treatments. Feeding the diNALLT and the CRPLT tended to reduce manure N excretion compared with the control and the εNALLT. Overall, results from the current study suggest that supplementing a Lys derivative, diNALL, to mid- to late-lactation dairy cows resulted in similar production performance relative to a commercial rumen-protected Lys product. A sizable increase in feed conversion efficiency (milk yield/DMI) and a trend for a reduction in manure N excretion when cows were supplemented with diNALL resulted from its effect to reduce DMI and N intake. This result indicates that the developmental diNALL product is metabolically active in lactating dairy cows. Further investigation is warranted to understand the biological availabilities of NALL in lactating dairy cows.

The crucial role of lysine in the hepatic metabolism of growing Holstein dairy heifers as revealed by LC-MS-based untargeted metabolomics.

The objective of this experiment was to evaluate the effect of supplementing rumen-protected Lys based on a Lys-deficient diet on liver metabolism in growing Holstein heifers. The experiment was conducted for 3 months with 36 Holstein heifers (initial body weight: 200 ± 9.0 kg; 7-month-old). Heifers were randomly assigned to 2 diets based on corn, soybean meal, alfalfa hay, and wheat bran: control, Lys-deficient diet (LD; 0.66% Lys in diet), and Lys-adequate diet (LA; 1.00% Lys in diet). The results showed no difference in growth performance between the 2 groups (P > 0.05). However, there was a clear trend of increasing feed conversion rate with Lys supplementation (0.05 < P < 0.01). The serum urea nitrogen concentration was significantly decreased, and the aspartate aminotransferase-to-alanine aminotransferase ratio was significantly decreased by Lys supplementation (P < 0.05). Moreover, growing heifers fed a Lys-adequate diet had lower levels of urine nitrogen excretion and higher levels of the biological value of nitrogen (P < 0.05). Metabolomic analysis revealed that 5 types of phosphatidylcholine and 3 types of ceramide were significantly increased and enriched in sphingolipid metabolism and glycerophospholipid metabolism (P < 0.05). His, Leu, and Asp levels were significantly decreased in the liver following Lys supplementation (P < 0.05). In conclusion, Lys supplementation may promote the synthesis of body tissue proteins, as evidenced by significantly decreased amino acids in the liver and urine N excretion, it also improves hepatic lipid metabolism by providing lipoprotein precursors.

218 Replacement of Soybean Meal with Corn DDGS and Crystalline Amino Acids Impacts Performance and Carcass Characteristics of Finishing Pigs

Abstract This study evaluated the effects of replacing soybean meal (SBM) with DDGS and crystalline amino acids on growth, carcass lean, and carcass yield of finishing pigs. Pigs (n = 480; 83.1±0.35 kg) were blocked by BW and sex and assigned to 80 pens (3 gilts and 3 barrows/pen). Treatments were arranged as a 2×4 factorial with DDGS included at 0 or 20% and L-lysine·HCl (LYS) added at 0.0, 0.2, 0.4, or 0.6%. Diets were balanced for ideal protein and NE and contained 0.75% and 0.67% SID lysine for Phase 1 (21 days) and Phase 2 (to market, 13 or 20 days), respectively. Only 0.49% LYS was necessary to meet the SID lysine requirement for the highest LYS (0.6%) diet for Phase 2. As LYS increased, dietary SBM inclusion decreased from 21.75% to 2.85% (Phase 1) and 18.75% to 3.35% (Phase 2) for control diets. It decreased from 18.40% to 0% (Phase 1) and 15.40 to 0% (Phase 2) for DDGS diets. During Phase 1, DDGS decreased ADG (992 vs. 1039 g/d; P = 0.031) and ADFI (3424 vs. 3503 g/d; P = 0.061). Increasing LYS linearly decreased ADG (1031, 1037, 1035, 959 g/d; P=0.026) and G:F (299, 295, 298, 281 g/kg; P = 0.026). Treatments did not impact Phase 2 performance. Overall, DDGS reduced ADG (1098 vs. 1131 g/d; P = 0.048) and ADFI (3638 vs 3712 g/d; P = 0.070). Supplemental LYS linearly decreased ADG (1133, 1141, 1120, and 1064 g/d; P = 0.005) and G:F (310, 305, 304, and 295 g/kg; P = 0.006). ADFI increased quadratically (P = 0.002) with LYS within SBM control, but not DDGS (interaction; P = 0.009). Ultrasound loin-eye-area corrected for BW tended to decrease quadratically (48.3, 48.8, 49.1, 47.4 cm2; P = 0.060) with increasing LYS. DDGS reduced carcass yield (72.62 vs. 73.04%; P = 0.034). Replacement of SBM with DDGS and high amino acid inclusion negatively impacted growth performance and carcass yield of finisher pigs.

Influences of timing of liver abscess control and early metabolizable amino acid supplementation on feedlot growth-performance and digestive function of calf-fed Holstein steers

Our objective was to examine the influence of timing of liver abscess control and early rumen-protected AA supplementation on cattle growth performance (Exp. 1) and digestive function (Exp. 2), and related responses on liver abscess incidence and AA supply to the small intestine of feedlot steers. In Exp. 1, a total of 200 calves were used in a 321-d experiment. Four strategies for liver abscess control using virginiamycin (VM; 16 mg of VM/kg of diet DM, Phibro Animal Health) were used: (1) 0% VM; (2) VM supplementation during the initial 168 d; (3) VM supplementation during the final 153 d; and (4) VM supplemented continuously for 321 d. During the initial 168-d feeding period, 2 levels of rumen-protected Met and Lys (Smartamine ML: SML; 0 vs. 0.6% DM basis, Adisseo) were supplemented across VM treatments in a 2 × 4 factorial arrangement. In Exp. 2, 4 Holstein steers (382 ± 23 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square design to evaluate treatment effects on digestion. Cattle growth performance was not affected ( P ≥ 0.18) by VM supplementation strategy. Moreover, VM supplementation did not affect ( P ≥ 0.10) carcass characteristics. Liver abscess incidence was low (4%) and not affected ( P ≥ 0.62) by supplementation strategy. Supplemental VM did not affect characteristics of ruminal and total-tract digestion ( P ≥ 0.27). Supplementation of SML during the first 168 d decreased ( P = 0.02) DMI during the last 153 d of the experiment, and tended to decrease ( P = 0.07) overall (321-d) DMI. Smartamine ML supplementation did not affect ( P ≥ 0.11) ADG, G:F, carcass characteristics, percentage of abscessed liver, or characteristics of ruminal and total-tract digestion. Timing of VM supplementation did not influence cattle growth performance or incidence of liver abscess, which was low (4%) regardless of VM treatment. Protected Met and Lys supplementation increased Met or Lys supply to the small intestine. However, MP and AA supplies of the basal diet, alone, were apparently adequate to achieve expected growth performance.

Effect of rumen-protected lysine supplementation of diets based on corn protein fed to lactating dairy cows

This trial tested whether rumen-protected Lys (RPL) supplementation would improve the nutritive value of rumen-undegradable protein (RUP) from corn protein. Thirty-two lactating Holstein cows were blocked by days in milk and parity into 8 squares of 4 cows each in replicated 4 × 4 Latin squares. Treatments provided all supplemental crude protein from: (1) soy protein (67% expeller soybean meal plus 33% solvent soybean meal); (2) a blend of soy and corn protein (33% expeller soybean meal, 17% solvent soybean meal, 25% corn gluten meal plus 25% distillers dried grains with solubles); (3) corn protein (50% corn gluten meal plus 50% distillers dried grains with solubles); or (4) corn protein plus RPL [diet 3 top-dressed with RPL (125 g/d of AjiPro-L Generation 1, supplying an estimated 20 g of absorbable Lys/d)]. Diets contained (dry matter basis) 22% alfalfa silage, 43% corn silage, 18% ground high-moisture and dry corn, 2.4% mineral-vitamin premix, 1.5 to 3.9% soy hulls, 15% crude protein, 30 to 32% neutral detergent fiber and predicted to contain equal rumen-degradable protein, RUP, and metabolizable protein. Cows within squares were randomly assigned to treatment sequences and fed diets for 4-wk periods before switching; production data and blood samples were collected during last 2 wk of each period. Data were analyzed using the mixed procedures of SAS. Intake was highest on diet 1, intermediate on diets 2 and 3, and lowest on diet 4; body weight gain was highest on diet 3, intermediate on diets 1 and 2 and lowest on diet 4. Intakes and body weight changes were reflected by differences in milk/dry matter intake, which was highest on diets 2 and 4 and lowest on diet 3. Milk yield was lower on diet 3 (44.3 kg/d) than on diets 1, 2, and 4 (average 45.8 kg/d) and protein yield was highest on diets 1 and 2 (average 1.35 kg/d), intermediate on diet 4 (1.30 kg/d), and lowest on diet 3 (1.25 kg/d). No effects of diet were detected on ruminal metabolites. Free nonessential amino acids and total protein AA were elevated in blood plasma on diet 3, reflecting reduced utilization for milk protein synthesis. These results indicated that 50% dilution of soybean meal RUP with that from corn protein did not reduce yield and that supplementing RPL to the corn protein-based diet increased yield 1.1 kg of milk/d and 50 g of true protein/d.

PSIX-29 JAK2-STAT3 Pathway Mediated Satellite Cell Apoptosis to Govern Skeletal Muscle Growth with Lysine

Abstract Apoptosis is programmed cell death that can be stimulated by external stress or nutrition restrictions. Lysine (Lys) is an essential amino acid for pig growth, and the relationship between Lys deficiency caused apoptosis and inhibition of skeletal muscle growth remains unknown. The objective of this study was to investigate whether apoptosis could be regulated by Lys supplementation and the potential mechanism. In current work, 30 male Duroc × Landrace × Large weaned piglets were divided randomly into 3 groups: control group (Lys 1.30%), Lys deficiency group (Lys 0.86%), and Lys rescue group (Lys 0.86%, 0-14d; 1.30%,15–28 d). The experiment lasted for 28 days, and on the morning of 29 d, piglets were slaughtered to collect samples. Isobaric tag for relative and absolute quantification (iTRAQ) proteomics analysis of the longissimus dorsi muscle showed that Janus family tyrosine kinase (JAK)-signal transducer and activator of transcription (STAT) pathway was involved in Lys deficiency-induced apoptosis and inhibited skeletal muscle growth. Meanwhile, western blotting results of the longissimus dorsi muscle demonstrated that Lys deficiency caused apoptosis (P &amp;lt; 0.05) with the JAK2-STAT3 pathway inhibition (P &amp;lt; 0.05). Interestingly, apoptosis was suppressed (P &amp;lt; 0.05), and the JAK2-STAT3 pathway was reactivated (P &amp;lt; 0.05) after Lys re-supplementation in longissimus dorsi muscle. In addition, results of satellite cells (SCs) isolated from the longissimus dorsi muscle of 5-day-old Landrace piglets showed that Lys deficiency-induced apoptosis (P &amp;lt; 0.05) was mediated by the JAK2-STAT3 pathway inhibition (P &amp;lt; 0.05). Moreover, the JAK2-STAT3 pathway was reactivated (P &amp;lt; 0.05) by Lys re-supplementation and suppressed apoptosis in SCs (P &amp;lt; 0.05), and this effect was blocked (P &amp;lt; 0.05) after SCs treated with AG-490 (a specific inhibitor of JAK2). Collectively, Lys inhibited apoptosis in SCs to govern skeletal muscle growth via the JAK2-STAT3 pathway.

Effects of Lysine and Methionine supplementation on first antler growth in fallow deer (Dama dama)

• The supplementation of Ruminally Protected Lysine 5 g per animal and day did not improve any antler characteristics • The combination of Lysine 9 g and Methionine 3 g per animal and day increased antler burr perimeter • Amino acids had direct effects on antlers and not mediated by body weight of animals • The positive effect of amino acids on antler properties is more intense in situations when the animals have a lower performance Amino acid supplementation in cervids is an almost unexplored research area. Lysine (Lys) and Methionine (Met) are the two amino acids considered as limiting for ruminants and Lys supplementation shows good potential for increased antler growth as it is the main component of collagen and a bone tissue precursor. However, several studies in other ruminants have shown greater effects when simultaneously supplementing Lys + Met. Two experiments based on Lys and Met supplementation during first antler growth were conducted during two consecutive years. Each experiment involved 45 yearling fallow bucks distributed in three groups, balanced by weight: Exp.1: Pasture , Pasture + Barley (0.2 kg/animal per day), and Pasture + Barley + Lys (5 g/animal per day); Exp.2: Pasture + Barley (0.5 kg/animal per day), Pasture + Barley + Lys (9 g/animal per day), and Pasture + Barley + Lys + Met (9 and 3 g/animal per day, respectively). Lys supplementation during the first experiment did not improve any antler characteristics ( P > 0.05). However, in the second experiment, both Lys (9 g) and Lys + Met treatments had positive effects on the external antler characteristics ( P = 0.013), antler weight ( P = 0.061) and particularly on the burr perimeter ( P = 0.008), which is crucial for antler size in following years. The results also suggest a stronger positive effect of amino acid supplementation on antler growth when the animals have a low performance in the presence of poorer pasturing situation.

MTORC1-Mediated Satellite Cell Differentiation Is Required for Lysine-Induced Skeletal Muscle Growth.

Skeletal muscle is the primary source of protein for humans. However, the mechanisms of skeletal muscle growth, such as nutrition control, remain unknown. Moreover, the function of lysine (Lys) in controling skeletal muscle growth has gradually demonstrated that Lys is not only substantial for protein synthesis but also a signaling molecule for satellite cell (SC) activation. In the current work, the number of differentiated SCs in the longissimus thoracis muscle and the fusion index of SCs were both governed by Lys supplementation. Meanwhile, the myogenic regulatory factors and the mammalian target of rapamycin complex 1 (mTORC1) pathway showed the same tendencies of changes as the differentiation of SCs. After Lys was resupplemented with rapamycin, the mTORC1 pathway was inhibited and the differentiation ability of SCs was suppressed. Collectively, the results showed that the mTORC1-pathway-mediated SC differentiation was required for Lys-promoted skeletal muscle growth.

MTORC1 Mediates Lysine-Induced Satellite Cell Activation to Promote Skeletal Muscle Growth.

As the first limiting amino acid, lysine (Lys) has been thought to promote muscle fiber hypertrophy by increasing protein synthesis. However, the functions of Lys seem far more complex than that. Despite the fact that satellite cells (SCs) play an important role in skeletal muscle growth, the communication between Lys and SCs remains unclear. In this study, we investigated whether SCs participate directly in Lys-induced skeletal muscle growth and whether the mammalian target of rapamycin complex 1 (mTORC1) pathway was activated both in vivo and in vitro to mediate SC functions in response to Lys supplementation. Subsequently, the skeletal muscle growth of piglets was controlled by dietary Lys supplementation. Isobaric tag for relative and absolute quantitation (iTRAQ) analysis showed activated SCs were required for longissimus dorsi muscle growth, and this effect was accompanied by mTORC1 pathway upregulation. Furthermore, SC proliferation was governed by medium Lys concentrations, and the mTORC1 pathway was significantly enhanced in vitro. After verifying that rapamycin inhibits the mTORC1 pathway and suppresses SC proliferation, we conclude that Lys is not only a molecular building block for protein synthesis but also a signal that activates SCs to manipulate muscle growth via the mTORC1 pathway.

The Limiting Sequence and Appropriate Amino Acid Ratio of Lysine, Methionine, and Threonine for Seven- to Nine-Month-Old Holstein Heifers Fed Corn-Soybean M-Based Diet.

Simple SummaryResearch on the amino acid nutrition of cattle is limited, particularly research on the amino acid patterns of growing heifer. This lack of research has made it difficult to minimize the costs and reduce nitrogen emission of dairy heifers. Lysine might be the first limiting amino acid for seven- to nine-month-old Holstein heifers that are fed a corn–soybean meal-based diet, followed by methionine and threonine. The appropriate ratio of lysine, methionine, and threonine—calculated based on the nitrogen retention of seven- to nine-month-old Holstein heifers—were 100:32:57. We expect to reduce the input of protein feed and nitrogen emissions for dairy farms by using this ratio.An “Amino acid (AA) partial deletion method” was used in this experiment to study the limiting sequences and appropriate ratio of lysine (Lys), methionine (Met), and threonine (Thr) in the diets of 7- to 9-month-old Holstein heifers. The experiment was conducted for three months with 72 Holstein heifers (age = 22 ± 0.5 weeks old; BW = 200 ± 9.0 kg; mean ± standard deviation). Following an initial two weeks adaptation period, heifers were allocated to one of four treatments: a theoretically balanced amino acid diet (positive control [PC]; 1.00% Lys, 0.33% Met, and 0.72% Thr), a 30% Lys deleted diet (partially deleted Lys [PD–Lys]; 0.66% Lys, 0.33% Met, and 0.72% Thr), a 30% Met deleted diet (partially deleted Met, [PD–Met]; 1.00% Lys, 0.22% Met, and 0.72% Thr), and a 30% Thr deleted diet (partially deleted Thr [PD–Thr]; 1.00% Lys, 0.33% Met, and 0.45% Thr). Experimental animals were fed a corn–soybean meal-based concentrate and alfalfa hay. In addition, the animals were provided with supplemental Lys, Met, and Thr (ruminal bypass). The results found no differences in the growth performance and nitrogen retention between PD–Thr treatment and PC treatment (p > 0.05). The average daily gain (p = 0.0013) and feed conversion efficiency (p = 0.0057) of eight- to ninr-month-old heifers were lower in both PD–Lys and PD–Met treatment than those in PC treatment. According to growth performance, Lys was the first limiting AA, followed by Met and Thr. Moreover, nine-month-old Holstein heifers in PD–Lys treatment and PD–Met treatment had higher levels of serum urea nitrogen (p = 0.0021), urea nitrogen (p = 0.0011) and total excreted N (p = 0.0324) than those in PC treatment, which showed that nitrogen retention significantly decreased (p = 0.0048) as dietary Lys and Met levels decreased. The limiting sequence based on nitrogen retention was the same as that based on growth performance. The appropriate ratio of Lys, Met, and Thr in the diet based on nitrogen retention was 100:32:57. In summary, the limiting sequence and appropriate amino acid ratio of Lys, Met, and Thr for seven- to nine-month-old Holstein heifers fed a corn–soybean meal-based diet were Lys > Met > Thr and 100:32:57, respectively.

The effect of finishing diet supplemented with methionine/lysine and methionine/α-tocopherol on performance, carcass traits and meat quality of Hanwoo steers.

ObjectiveThis study aimed to compare the effects of diets with and without supplements of methionine/lysine (met/lys) and methionine/α-tocopherol (met/α-tocopherol) on the performance, carcass traits and meat quality of Hanwoo steers.MethodsA total of 21 Hanwoo steers were divided into three different groups. Each group consisted of 7 animals that received different dietary treatments for 120 days as follows: a control (C) diet composed of a basal diet with 74% total digestible nutrient and 12% crude protein; treatment 1 (T1) composed of a basal diet enriched with methionine 69%+lysine 31%; and treatment (T2) composed of a basal diet enriched with methionine 84.65%+α-tocopherol 15.35%. Daily supplementation was given using the top-dressing method (20 g/animal).ResultsThe met/lys groups yielded a longissimus lumborum with increased water holding capacity (p<0.01) and lower shear force value (p<0.05). Dietary met/lys did not have an adverse effect on the animal performance and carcass traits. Instead, these supplements contributed significantly to the higher protein content compared to the control diet (p<0.05). Myristic acid (C14:0) was the only fatty acid affected by the supplementation. While the met/α-tocopherol group led to significantly higher protein and oxymyoglobin contents during storage (p<0.05). It also contributed significantly to the lower shear force value and 2-thiobarbituric acid reactive substances score during storage (p<0.05) compared to the control and treatment 1 since the initial storage day. The met/α-tocopherol diet also yielded meat with a redder color (p<0.05) after 3 days of storage. However, it did not significantly contribute to the fatty acid profiles of Hanwoo steers.ConclusionMet/lys supplementation resulted in higher protein scores, water holding capacity and lower shear force scores. While met/α-tocopherol supplementation contributes to the production of redder meat, reduces lipid oxidation, production of more tender meat and increases the content of protein and oxymyoglobin percentage.

Dietary supplementation with L-lysine affects body weight and blood hematological and biochemical parameters in rats.

L-Lysine (Lys) is a popular additive in foods, but the physiological effects of excess Lys supplementation are poorly understood and upper limits of safe intake have not been established. The objectives of this study were to examine the effects of dietary supplementation with increasing amounts of Lys on body weight (BW), food intake, and various blood hematological and biochemical parameters in rats. Male Sprague-Dawley rats at 10weeks of age were assigned to ten diet groups (eight rats/group) and fed diets containing either 7% or 20% casein and supplemented with either 0% (Control), 1.5%, 3%, 6% Lys, or 6% Lys + 3% arginine for 1 week. Rats fed 7% casein with ≥ 1.5% Lys supplementation had lower serum albumin and leptin and higher LDL cholesterol (LDLC), ratios of total cholesterol (TC):HDL cholesterol (HDLC) and LDLC:HDLC than those fed 7% casein Control diet (P < 0.05). Rats fed 7% casein diet supplemented with 3% Lys diet had lower BW gain, food intake, serum alkaline phosphatase activity, and increased mean corpuscular hemoglobin concentration, blood urea nitrogen and serum pancreatic polypeptide compared to rats fed the Control diet (P < 0.05). Addition of 6% Lys in 7% casein caused significant BW loss (P < 0.001) and altered additional parameters. Addition of 6% Lys in a 20% casein diet reduced BW gain and food intake and altered numerous parameters. Arg supplementation normalized many of the endpoints changed by Lys. Collectively, these results show that Lys supplementation affects BW, food intake and a number of hematological and biochemical parameters. These effects of Lys supplementation were confined primarily in diets with lower levels of dietary protein. In the context of a low protein diet (7% casein), levels of Lys supplementation ≥ 1.5% may exert adverse health effects in rats.

Dietary L-lysine supplementation altered the content of pancreatic polypeptide, enzymes involved in glutamine metabolism, and β-actin in rats.

This study investigated the effects of Lys supplementation on serum pancreatic polypeptide (PP), glutamine (Gln) levels and the expression of PP, Gln synthetase (GlnS), glutaminase (Gls) and β-actin in different tissues such as pancreas, skeletal muscle, liver and kidney in rats. Male Sprague-Dawley rats were fed diets containing 7% casein supplemented with either 0% (Control), 1%, 1.5%, 3% Lys or 3% Lys with 1.5% Arg for a week. All rats were necropsied for collection of blood and tissues. Expression of PP, GlnS, Gls, and β-actin in tissues were determined using Western blotting. The results showed that the rats fed 3% supplemental Lys had significantly lower body weight gain (BWG) and food intake than the ≤ 1.5% Lys groups (P < 0.05). Supplementation with ≥ 1% Lys increased serum PP level (P < 0.05), but had no significant effect on pancreatic PP abundance (P > 0.05). GlnS expression was significantly lowered in skeletal muscle by ≥ 1.5% supplemental Lys compared to the Control (P < 0.05). The expression of Gls in the kidney was increased by the addition of 1.5% Arg to 3% Lys diet (P < 0.05). Liver β-actin significantly increased with both Lys and Arg supplementation and muscle β-actin significantly decreased (P < 0.05) with ≥ 1.5% supplemental Lys. Kidney β-actin significantly increased with Arg supplementation vs 3% Lys alone (P < 0.05). These results showed that dietary supplementation with ≥ 1.5% Lys significantly suppressed GlnS expression in the skeletal muscle, which may contribute to the decreased serum Gln levels, and that increased serum PP by Lys may be due to suppressed catabolism rather than increased synthesis of PP. Lys-induced PP may play a role in reducing food intake and BWG.

Supplementing Beef Steers with Ruminal Bypass Arginine Improves Oxidative Stability of Aged Beef Loins

ObjectivesSupplementation of ruminal bypass amino acids, such as arginine (Arg) and lysine (Lys), in beef cattle rations has been suggested to improve growth performance, feed efficiency and carcass composition. However, its impacts on meat quality characteristics have not been fully investigated. Previous studies have indicated supplementation of Arg may have an antioxidative effect on skeletal muscle. Postmortem aging is widely practiced in the beef industry to improve eating quality characteristics, but extended aging period has been shown to adversely affect oxidative stability, resulting in rapid discoloration and/or off-flavor development. Hence, this study was conducted to evaluate the effects of ruminal bypass Arg and Lys supplementation on meat quality and oxidative stability of beef loins with 14 and 28 d aging times. Materials and MethodsForty cattle fed 4 different diets for 180 d (control-basal diet; additional supplementation of metabolizable treatments (10 g/d) of each Arg, Lys, and ArgLys, respectively) were harvested. At 1 d postmortem, paired loins (M. Longissimus lumborum) were separated from each carcass, vacuum-packaged, and assigned to 14 and 28 d aging at 2°C. After each assigned aging time, 3 beef steaks (2-cm thick) were made from each loin to measure meat quality attributes, such as pH, water-holding capacity (WHC) and Warner-Bratzler shear force. One steak was overwrap-packaged with polyvinylchloride film and displayed for 7 d at 2°C under fluorescent light (1450 lx) for instrumental and trained panel color evaluation. Oxidative stability was determined by measuring total reducing activity (TRA) and 2-thiobarbituric acid reactive substances (TBARS). The experimental design was a split-plot design with diet effect as whole plot and aging time as sub-plot. All data were analyzed using the PROC MIXED procedure of SAS version 9.4 (SAS Inst. Inc., Cary, NC), and means were separated by least significant differences (P 0.05). An increase in aging duration decreased shear force (P 0.05). This could indicate a synergistic ArgLys combination impact on oxidative stability of beef samples. ConclusionThe results of this study suggest that Arg supplementation could be an effective strategy to improve color stability of beef loins with extended aging. Further studies to elucidate the mechanism through which Arg mitigates the negative effects of extended aging storage on color and oxidative stabilities are highly warranted. In particular, the influence of Arg supplementation on the synthesis of nitric oxide (NO) via the L-arginine-NO pathway in aged beef loins is under investigation.

Standardized ileal digestible lysine in diets for pigs fed ractopamine in commercial production system

Two consecutive experiments were conducted using 480 pigs each with six replicate pens per treatment and 10 pigs per pen to evaluate the effect of standardized ileal digestible (SID) Lys (0.81, 0.91, 1.01, and 1.11%) in diets containing ractopamine (RAC; 10 or 20 mg kg-1) on growth and carcass traits of barrows in a commercial production system. There were no effects of either RAC levels or the interaction between RAC and SID Lys levels on any of the performance and carcass variables. No lack of fit was detected in the response surface analysis. From d 0 to 21, there was no effect of SID Lys levels on ADFI. However, as SID Lys increased, there was a linear increase in ADG and G:F. As SID Lys increased, the ADG, G:F, loin depth, and lean percentage improved linearly from d 0 to 28, with no effect on ADFI and backfat thickness. In conclusion, performance and carcass traits of pigs fed RAC (10 or 20 mg kg-1) in a commercial finishing facility are improved by up to 1.11% SID Lys supplementation. There is no additional benefit of feeding 20 mg kg-1 RAC in comparison with 10 mg kg-1 RAC.

Critical analysis of excessive utilization of crude protein in ruminants ration: impact on environmental ecosystem and opportunities of supplementation of limiting amino acids—a review

Protein quality plays a key role than quantity in growth, production, and reproduction of ruminants. Application of high concentration of dietary crude protein (CP) did not balance the proportion of these limiting amino acids (AA) at duodenal digesta of high producing dairy cow. Thus, dietary supplementation of rumen-protected AA is recommended to sustain the physiological, productive, and reproductive performance of ruminants. Poor metabolism of high CP diets in rumen excretes excessive nitrogen (N) through urine and feces in the environment. This excretion is usually in the form of nitrous oxide, nitric oxide, nitrate, and ammonia. In addition to producing gases like methane, hydrogen carbon dioxide pollutes and has a potentially negative impact on air, soil, and water quality. Data specify that supplementation of top-limiting AA methionine and lysine (Met+Lys) in ruminants' ration is one of the best approaches to enhance the utilization of feed protein and alleviate negative biohazards of CP in ruminants' ration. In conclusion, many in vivo and in vitro studies were reviewed and reported that low dietary CP with supplemental rumen-protected AA (Met+Lys) showed a good ability to reduce N losses or NH3. Also, it helps in declining gases emission and decreasing soil or water contamination without negative impacts on animal performance. Finally, further studies are needed on genetic and molecular basis to explain the impact of Met+Lys supplementation on co-occurrence patterns of microbiome of rumen which shine new light on bacteria, methanogen, and protozoal interaction in ruminants.

Effects of dietary energy and lysine levels on growth performance and carcass yields of Pekin ducks from hatch to 21 days of age

A 2 × 6 factorial experiment, using 2 dietary apparent metabolizable energy (AME) levels (2,750 and 3,050 Kcal/kg) and 6 supplemental lysine (Lys) levels (0, 0.10, 0.20, 0.30, 0.40, and 0.50%), was conducted to study the effects of dietary energy and lysine levels on growth performance and carcass yields of Pekin ducks from hatch to 21 d of age. A total of 576 one-day-old male White Pekin ducks was randomly allotted to 12 dietary treatments, each containing 6 replicate pens with 8 birds per pen. At 21 d of age, body weight gain, feed intake, and feed/gain were measured, and then 2 ducks selected randomly from each pen were slaughtered to evaluate the yields of abdominal fat, breast meat, and leg meat. As a result, birds that were fed basal diets with no Lys supplementation showed growth depression, and significant positive effects of dietary Lys supplementation on body weight gain (P < 0.001), feed intake (P < 0.001), and feed/gain (P = 0.002) were observed as dietary Lys increased gradually among all the groups. In addition, increasing energy levels did not affect overall body weight gain (P > 0.05), but feed intake (P = 0.001) and feed/gain (P = 0.009) decreased significantly between the groups. Dietary Lys levels influenced the yields of breast (P < 0.001) and leg (P = 0.001) meat among all the groups, but dietary energy levels had a significant positive effect only on abdominal fat yield (P = 0.014). The interaction between dietary energy and Lys influenced body weight gain of ducks significantly (P = 0.004). According to the broken-line regression analysis, Lys requirements of Pekin ducks for weight gain at 2,750 and 3,050 Kcal of AME/kg were 0.94 and 0.98%, respectively. It suggested that Lys requirement was higher at 3,050 Kcal of AME/kg than at 2,750 Kcal of AME/kg. Dietary energy content determined feed intake of the ducks, and high-energy diets will require a higher amino acid concentration to compensate for a lower feed intake.

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.

L-Lysine suppresses myofibrillar protein degradation and autophagy in skeletal muscles of senescence-accelerated mouse prone 8.

Sarcopenia is a condition of the loss of muscle mass that is associated with aging and that increases the risk for bedridden state, thereby warranting studies of interventions that attenuate sarcopenia. Here the effects of 2-month dietary L-lysine (Lys) supplementation (1.5-3.0%) on myofibrillar protein degradation and major proteolytic systems were investigated in senescence-accelerated mouse prone 8 (SAMP8). At 36weeks of age, skeletal muscle and lean body mass was reduced in SAMP8 when compared with control senescence-accelerated mouse resistant 1 (SAMR1). The myofibrillar protein degradation, which was evaluated by the release of 3-methylhistidine, was stimulated in SAMP8, and the autophagy activity, which was evaluated by light chain 3-II, was stimulated in the skeletal muscle of SAMP8. The activation of ubiquitin-proteasome system was not observed in the muscles of SAMP8. However, myofibrillar protein degradation and autophagic activity in skeletal muscles of SAMP8 were suppressed by dietary intake of 3.0% Lys. The present data indicate that myofibrillar protein degradation by bulk autophagy is stimulated in the skeletal muscles of SAMP8 and that dietary Lys supplementation attenuates sarcopenia in SAMP8 by suppressing autophagic proteolysis.