Lysine Supplementation Research Articles

14 Predicting Performance Responses of Growing Cattle to Amino Acid Supplementation

Abstract Amino acid utilization by cattle can be studied by: 1) assessing amino acid requirements with foundational research and using the resultant information to predict animal performance, or 2) evaluating changes in animal performance in response to changes in amino acid supply and subsequently using those measures to predict amino acid requirements. Neither approach has yielded definitive results, and our ability to predict responses of cattle to amino acid supplementation is still quite limited after many years of research. Most supplementation studies have focused on methionine and lysine, amino acids for which ruminally protected products are commercially available. Most finishing cattle fed diets typical of the U.S. feedlot industry are not responsive to methionine or lysine supplementation, although little research is available for cattle fed beta-agonists. In some cases, growing cattle fed corn-based diets have demonstrated performance responses to lysine supplementation. Growing cattle fed forage-based diets, particularly those based on grass silages, appear responsive to supplemental amino acids. Numerous studies with Holstein steers (150 to 250 kg) maintained in a research model to make amino acids the most limiting nutrient have demonstrated linear increases in nitrogen retention, followed by a plateau, when limiting amino acids were supplemented. From those studies, maintenance requirements for amino acids appear to be small, and efficiencies of amino acid utilization for growth are less than predicted by NASEM (2016). Some factors that would be expected to increase the likelihood that amino acids are the most limiting nutrient include: decreased body weight, greater mature body weight, environments that minimize maintenance energy requirements, and diets that lead to redued amounts of microbial protein synthesis (energy sources such as fat and ruminally resistant starch). Despite the many unknowns associated with amino acid requirements of cattle for growth, potential exists to use amino acid supplementation to improve economics of cattle performance or reduce environmental impacts of cattle production.

PSII-12 Growth Performance of Pigs Fed Diets Containing Supplemental Lysine and a Low or High Essential Amino Acid-Nitrogen to Total Nitrogen Ratio

Abstract With the provision of low protein (LP) diets, it is possible that N, or non-essential amino acids (NEAA), become limiting. We have previously shown that the lysine (Lys) requirement for N retention is greater when pigs are fed a diet with sufficient N, as indicated by a low EAA-N:total N ratio (EAA-N:TN). The objective of this study was to investigate the effect of EAA-N:TN and Lys content on growth performance of growing pigs. A total of 240 growing pigs (20.6 ± 2.03 kg initial body weight) were randomly placed into groups of 5 pigs/pen (either 2 barrows and 3 gilts, or 3 barrows and 2 gilts) and randomly assigned to 1 of 4 dietary treatments (n = 12 pens/treatment) in 3 blocks in a 2 × 2 factorial design. Factors consisted of dietary EAA-N:TN [optimal ratio (LR) of 0.48 or high ratio (HR) of 0.55] and dietary Lys level of 1.03% SID or 1.22% SID, representing the NRC (2012) requirement and the requirement as determined previously, respectively. Diets were corn and soybean meal based and formulated to meet or exceed nutrient requirements according to NRC (2012). Pigs were individually weighed and feed intake determined weekly to determine average daily gain (ADG), average daily feed intake (ADFI), and gain:feed (G:F). Fecal samples were collected on d 14 for determination of N output. Data were analyzed using a mixed model with fixed effects of ratio, lysine, and their interaction and block as a random effect. Increasing dietary Lys resulted in increased overall ADG and ADFI, regardless of EAA-N:TN ratio (P < 0.01). Pigs fed the HR diets had improved ADG in week 4 (P < 0.05), whereas pigs fed the LR diets had improved ADG and G:F in week 1 (P < 0.01). There was an interactive effect of ratio and Lys on N output (P < 0.01), where N output decreased in the HR diets with 1.22% Lys. Overall, current Lys requirements may not be sufficient to maximize growth in 20-50 kg pigs, and greater Lys may be beneficial for reducing N output in LP diets.

Effect of Replacing Fish Meal by Soybean Meal on the Performance, Nutrient Utilization and Egg Quality of Khaki Campbell Ducks in Late Laying Phase

Background: Feed quality in terms of protein source plays an important role in achieving targeted production. The quality of fish meal available in market is of highly variable in nature. Hence, an attempt was made to see the response of laying ducks to diets where fish was replaced by soybean meal with supplementation of critical aminoacids i.e. lysine and methionine over and above the normal requirement. Methods: A 16 week biological trial consisting of 72 Khaki Campbell laying ducks (83 weeks) subjected to three treatments (T1-Control diet with fish meal, T2- fish meal totally replaced by soybean meal, T3-T2 + Supplementation of Lysine and Methionine distributed equally to 9 replications of 8 laying ducks each was conducted following completely randomised design to see the effect of treatments on the performance, nutrient digestibility/retention and egg quality in Khaki Campbell laying ducks. Standard analytical and statistical procedures were followed for proper interpretation of the data. Result: The egg production (nos and dozen) and DDEP percent were significantly (P less than 0.05) higher and FCR was significantly (P less than 0.05) better for ducks reared on T1 compared to other groups. The dry matter, organic matter and crude fibre digestibility was significantly (P less than 0.05) higher for ducks fed fish meal. However, the EE digestibility was significantly (P less than 0.05) higher for T3 group. The egg quality parameters were significantly higher for T3 group. It is concluded that the performance of Khaki Campbell laying ducks fed diet without fish meal was deteriorated but the egg quality was improved.

An Evaluation of the Supplementation of Rumen-Protected Lysine and Methionine on the Lactation Performance of Fall Parturition Grazing Holstein Cows in Southern Chile.

The aim of this study was to evaluate the effect of the supplementation of rumen-protected (RP) methionine and lysine on milk yield, solids, and body weight over time on fall-calving grazing multiparous Holstein cows from Chile. Four treatment groups were studied and compared for the outcomes over time. The treatments were as follows: (i) CON: control (n = 26); (ii) RP lysine group (LYS; 20 g per cow per day; n = 26); (iii) RP methionine group (MET; 20 g per cow per day; n = 26); and (iv) LYS × MET (RP lysine and RP methionine 20 g of each amino acid per cow per day; n = 26). Data were analyzed with general linear mixed model ANOVAs for repeated measures to primarily test the main effects of each amino acid and their interactions. The supplementation of the amino acids was conducted from 2 to 70 days postpartum. Overall, milk production tended to be higher in the MET and in the LYS × MET group when compared to the control group. Furthermore, CON produced significantly less milk protein (kg) and milk fat (kg) than the LYS, MET, and LYS × MET groups. Milk urea tended to be lower during the entire study in the CON group than the rest of the groups. There was a trend for a reduction in the losses of postpartum body weight in the LYS × MET than the CON. In conclusion, RP methionine and lysine improved milk fat and protein yield in grazing multiparous cows with fall parturitions; consequently, both RP amino acids can be used as a strategy for improving grazing cows' production performance.

Rumen-protected lysine supplementation improved amino acid balance, nitrogen utilization and altered hindgut microbiota of dairy cows

This study was conducted to evaluate the effects of dietary crude protein (CP) and rumen-protected lysine (RPL) supplementation on lactation performance, amino acid (AA) balance, nitrogen (N) utilization and hindgut microbiota in dairy cows. Treatments were in a 2 × 2 factorial arrangement, and the main effects were CP concentration (16% vs. 18%) and RPL supplementation (with or without RPL at 40 g/cow per day). Forty cows were randomly allocated to 4 groups: low-CP diet (LP), low-CP diet plus RPL (LPL), high-CP diet (HP), high-CP diet plus RPL (HPL). The experiment was conducted for 8 weeks. Results showed that RPL increased the dry matter intake (P < 0.01), milk protein yield (P = 0.04) and energy corrected milk (P = 0.04), and tended to increase milk fat yield (P = 0.06) and fat corrected milk (P = 0.05). Cows in the HP group tended to have higher milk urea N (P = 0.07). Plasma concentrations of Arg, Ile, Lys, Met, Pro, total essential AA and total nonessential AA were increased by RPL (P < 0.05). The total essential AA, total nonessential AA and most AA (except Ile, Phe, Gly and Pro) were increased in the HP group (P < 0.05). N excretion was increased in the HP group through an increase in urea N excretion (P < 0.01) and an upward trend in plasma urea N (P = 0.07). In addition, RPL tended to increase milk protein N secretion (P = 0.08), milk N (P = 0.07) and microbial protein synthesis (P = 0.06), and decreased plasma urea N (P < 0.001). In the hindgut, the bacterial community were different between the LP and LPL groups (P < 0.01). The probiotic abundances of Christensenellaceae_R-7_group and Acinetobacter were increased by RPL (P = 0.03 and 0.03, respectively). The pathogenic abundances of Clostridium_sensu_stricto_1 (P < 0.001) and Turicibacter (P < 0.01) were decreased by RPL. In conclusion, supplementing RPL with low dietary CP could balance AA supply and increase milk protein yield, resulting in an improvement in N utilization efficiency, and altered the composition of the hindgut microbiota to favor the lactation performance of dairy cows.

Effects of Dietary Supplementation of Lysine and Methionine on Growth Performance, Blood Parameters and Body Composition of Common Carp (Cyprinus Carpio) Fingerling

Effects of Dietary Supplementation of Lysine and Methionine on Growth Performance, Blood Parameters and Body Composition of Common Carp (Cyprinus Carpio) Fingerling

Production Performance and Serum Biochemical Indices as Influenced by Lysine and Methionine Supplementation to Low Protein Diet in Vanaraja Laying Hens

An experiment was conducted to evaluate the effect lysine and methionine supplementation to low protein diet on production performance and serum biochemical parameters in Vanaraja laying hens. One hundred twenty (n=120), 30-weeks old Vanaraja laying hens were randomly distributed into four dietary treatments with three replicates in each group having 10 birds in each replicate. Four diets were formulated with 2600 kcal/kg of metabolizable energy (ME) and 13% crude protein (CP). The dietary treatments were: T1- diet contains 0.65% lysine and 0.28% methionine; T2- diet contains 0.70% lysine and 0.32% methionine; T3- diet contains 0.75% lysine and 0.36% methionine and T4- diet contains 0.80% lysine and 0.40% methionine. Body weight and its changes, Hen Housed Egg Production (HHEP), egg weight (g), egg mass (g/day), and feed conversion ratio and serum biochemical parameters found significantly (P&lt;0.05) differed across the dietary treatments during different phases of the experimental period. There was significant (P&lt;0.05) effect of lysine and methionine on the overall body weight gain. Serum biochemical parameters like albumin, globulin, creatinine, uric acid, triglycerides and AST activity varied due to supplementation of EAAs to low CP diet. So it was concluded that diet containing 0.65% lysine and 0.28% methionine (T1) is adequate for optimum production performance and serum biochemical indices in Vanaraja laying hens.

Lysine and threonine supplementation promotes postharvest quality of Volvariella volvacea mushroom during low-temperature preservation via maintenance of the citrate cycle

Volvariella volvacea, the edible straw mushroom, is popular among consumers; however, its freshness is difficult to maintain at 4 °C. Spray treatment with the ubiquitin-binding enzyme E2 (UBEV2) inhibitor L345-0044 maintained the freshness of V. volvacea during storage at 4 °C for 48 h. Inhibitor treatment enhanced the ability of V. volvacea to resist cold stress by inducing overexpression of genes involved in protein translation, protein turnover, N-glycan biosynthesis, and lysine metabolism. Overexpression of saccharopine dehydrogenase genes, which participate in lysine metabolism in yeast, enhanced freezing tolerance. Anti-freezing experiments showed that the addition of l-lysine or l-threonine improved the quality of V. volvacea at 4 °C with stable soluble sugar levels, as lysine or threonine metabolism produced acetyl-CoA for maintaining the citrate cycle. Our findings revealed that supplementation with l-lysine or l-threonine prolonged the preservation time of V. volvacea for more than 24 h via maintenance of the citrate cycle.

Effect of Milk or Milk Derived Food Supplementation on Body Composition of Young Indian Women

Background: Lysine intake in India is low mainly due to consumption of cereals as staple diet and processing loss of lysine. The present study was aimed to assess the impact of supplementation either in the form of dietary supplements of lysine, calcium and vitamin D in order to identify an appropriate approach for the improvement of body composition. Methods: One hundred and twenty volunteer subjects in the age group of 20-30 years residing in Punjab Agricultural University hostels were selected for supplementary trial. Supplementation of milk and its products in amounts to fill the gap of dietary intake and adequacy of protein as well as limiting amino acid lysine in their diets for a period of 12 weeks was done to determine its effect on body composition. Result: The diets were also poor in protein quality as the limiting amino acid lysine was only 55% of the recommended level. Supplementation of milk and its products resulted in a significant reduction in body fat (6.62%) and visceral fat rating (9.47%) and a significant increase in skeletal muscle mass (3.98%) and bone mass (2.72%). The study recommends that improving the quality of diets through dietary supplementation of lysine, calcium and vitamin D is an effective approach to achieve optimum body composition.

Supplementation of Cereal Proteins with Amino Acids: V. Effect of Supplementing Lime-Treated Corn with Different Levels of Lysine, Tryptophan and Isoleucine on the Nitrogen Retention of Young Children

A lime-treated corn diet was supplemented with two levels each of lysine and of tryptophan, as well as two levels of isoleucine with a constant lysine and tryptophan supplement. Comparison of corn protein with the FAO reference protein indicates tryptophan to be the first limiting amino acid and lysine the second. In 18 3-day balance periods in two children lysine supplementation alone somewhat improved nitrogen balance, but tryptophan addition had no effect. Analysis of 12 3-day balance periods in 4 children indicated that the addition of lysine to give 180 mg/g N in the diet (0.30% l-lysine·HCl) and of tryptophan to a total of 75 mg/ g N (0.28% dl-tryptophan) approximately doubled the percentage of nitrogen retention compared with the results when the basal diet was fed. Increasing the lysine to 270 mg/g N (0.56% l-lysine·HCl) or the tryptophan to 90 mg/g N (0.35% dl-tryptophan) either singly or together, did not improve significantly the nitrogen balance compared with that obtained with these amino acids at the lower levels of supplementation. The addition of isoleucine to 270 mg/g N (0.45% dl-isoleucine) to the 270 mg lysine/g N plus 25 mg tryptophan/g N resulted in a slightly higher nitrogen balance. The addition of isoleucine to a level of 225 mg/g N gave an intermediate value for nitrogen retention. None of the amino acid combinations used to supplement corn-masa resulted in as high nitrogen retention as those obtained from feeding isonitrogenous levels of milk. The variable results with supplementation of different cereals with essential amino acids to the level in the FAO reference protein provide further evidence that reference amino acid patterns should include both upper and lower limits for the amount of each amino acid per gram of nitrogen and specify the range of protein intake over which they apply.

Rumen-Protected Lysine and Methionine Supplementation Reduced Protein Requirement of Holstein Bulls by Altering Nitrogen Metabolism in Liver.

The aim of this study was to investigate the effect of low-protein diets supplemented with rumen-protected lysine (RPLys) and methionine (RPMet) on growth performance, rumen fermentation, blood biochemical parameters, nitrogen metabolism, and gene expression related to N metabolism in the liver of Holstein bulls. Thirty-six healthy and disease-free Holstein bulls with a similar body weight (BW) (424 ± 15 kg, 13 months old) were selected. According to their BW, they were randomly divided into three groups with 12 bulls in each group in a completely randomized design. The control group (D1) was fed with a high-protein basal diet (CP13%), while bulls in two low-protein groups were supplied a diet with 11% crude protein and RPLys 34 g/d·head + RPMet 2 g/d·head (low protein with low RPAA, T2) or RPLys 55 g/d·head + RPMet 9 g/d·head (low protein with high RPAA, T3). At the end of the experiment, the feces and urine of dairy bulls were collected for three consecutive days. Blood and rumen fluid were collected before morning feeding, and liver samples were collected after slaughtering. The results showed that the average daily gain (ADG) of bulls in the T3 group was higher than those in D1 (p < 0.05). Compared with D1, a significantly higher nitrogen utilization rate (p < 0.05) and serum IGF-1 content (p < 0.05) were observed in both T2 and T3 groups; however, blood urea nitrogen (BUN) content was significantly lower in the T2 and T3 groups (p < 0.05). The content of acetic acid in the rumen of the T3 group was significantly higher than that of the D1 group. No significant differences were observed among the different groups (p > 0.05) in relation to the alpha diversity. Compared with D1, the relative abundance of Christensenellaceae_R-7_group in T3 was higher (p < 0.05), while that of Prevotellaceae _YAB2003_group and Succinivibrio were lower (p < 0.05). Compared with D1 and T2 group, the T3 group showed an expression of messenger ribonucleic acid (mRNA) that is associated with (CPS-1, ASS1, OTC, ARG) and (N-AGS, S6K1, eIF4B, mTORC1) in liver; moreover, the T3 group was significantly enhanced (p < 0.05). Overall, our results indicated that low dietary protein (11%) levels added with RPAA (RPLys 55 g/d +RPMet 9 g/d) can benefit the growth performance of Holstein bulls by reducing nitrogen excretion and enhancing nitrogen efficiency in the liver.

Excess Dietary Lysine Increases Skeletal Muscle and Plasma Trimethyllysine in Rats

Trimethyllysine, a carnitine precursor, is a cation. This study was designed to determine whether dietary potassium and lysine concentration or oral lysine supplementation affects tissue carnitine and trimethyllysine concentration in rats. In Experiment 1, rats were fed a control diet, a low or high potassium diet, or a high lysine diet. In Experiment 2, rats were given by gavage a solution containing either L-proline (control) or L-lysine. In Experiment 1, rats fed the high lysine diet had significantly lower plasma total carnitine concentration than controls. Rats fed the high lysine diets had significantly higher concentrations of free trimethyllysine in skeletal muscle and plasma relative to control rats and rats fed the high potassium diet. Rats fed the low potassium diet had a similar increase in skeletal muscle free trimethyllysine. In Experiment 2, rats given lysine had significantly lower plasma total carnitine concentration, and significantly greater skeletal muscle and plasma trimethyllysine concentration relative to controls. We conclude that dietary potassium and lysine, and oral lysine, have a significant effect upon the distribution of carnitine and trimethyllysine in rats. The distributional changes caused by lysine, however, seem to be due to effects other than exchange of lysine for carnitine or trimethyllysine in tissues.

Combined Effect of Methionine, Lysine and Neem Leaf Meal Supplementation on Growth Performance, Blood Parameters and Oxidative Status of Finishing Broilers

Combined Effect of Methionine, Lysine and Neem Leaf Meal Supplementation on Growth Performance, Blood Parameters and Oxidative Status of Finishing Broilers

Effect of Egg Yolk and Carboxylated Poly-l Lysine (CPLL) Supplementation to Tris-Citrate Extender on Post-Thaw Semen Quality of Beetal Male Goats

Effect of Egg Yolk and Carboxylated Poly-l Lysine (CPLL) Supplementation to Tris-Citrate Extender on Post-Thaw Semen Quality of Beetal Male Goats

Influence of Dietary Lysine Level on Growth Performance, Feed Efficiency, and Body Composition of Sangkuriang Catfish (Clarias gariepinus var. Sangkuriang) Fingerlings

The high consumer demand in Indonesia encourages catfish farmers to conduct an intensive culture. A low feed efficiency mainly occurs in cultivating Sangkuriang catfish resulting in poor growth. This condition might be caused by low lysine content, as lysine is an essential amino acid that the fish cannot synthesize. The present study aimed to investigate the effect of lysine supplementation in feed on protein digestibility, feed efficiency, and growth of Sangkuriang catfish (Clarias gariepinus var. Sangkuriang) fingerlings. The study used 270 Sangkuriang catfish with an average wet weight of 7.54 ± 0.13 g/fish. The experimental feed contained protein, energy, and amino acid, and then various doses of lysine were added to the experimental feed: (1) 0.0%, (2) 0.5%, (3) 1.0%, (4) 1.5%, (5) 2.0%, and (6) 2.5%. Weight gain (WG), protein digestibility (ADCp), the efficiency of feed utilization (EFU), relative growth rate (RGR), feed conversion ratio (FCR), protein efficiency ratio (PER), and protein retention (PR) of catfish were evaluated for 8 weeks. The results found that the supplementation of lysine in feed significantly (P &lt; 0.05) influenced WG, ADCp, EFU, RGR, FCR, PER, and PR of Sangkuriang catfish fingerling. However, there was no significant effect (P &gt; 0.05) on the SR of Sangkuriang catfish fingerling. The supplementation of 1% lysine/kg feed was the optimal dose to improve the feed efficiency and growth of Sangkuriang catfish fingerlings by 83.79% and 3.94%/day, respectively. Therefore, the supplementation of lysine could increase Sangkuriang catfish production.

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This study was designed to check the dietary effect of different levels of lysine on intestinal morphology, cecal tonsils and goblet cell count in Japanese Quails. For this Purpose, a total of 100, day old chicks were randomly divided in four groups. These groups were further sub-divided into five replicas per group, each replica having five birds. NRC has recommended 13g/kg of lysine in basal diet in 1994. The birds of control group (first) were fed with basal diet containing 13 g/kg of lysine, second experimental groups fed contained lysine at the rate of 11.7g/kg of lysine, third group 13.6 g/kg of lysine and fourth group 14.9 g/kg, respectively for 35 days. The results showed a significant increase (P&lt;0.05) in villus height (VH), villus width (VW), villus surface area (VSA) and muscular mucosa thickness (MMT) in all parts of the small intestine of 13.65 g/kg supplemented birds. In jejunum, VH, VW, VSA, lamina propria thickness (LPT) and MMT was increased at levels 13.65 g/kg and 14.95 g/kg. Crypt depth (CD) and muscularis externa thickness (MET) did not vary in both duodenum and jejunum, in ileum CD and MET was increased (P&lt;0.005) in treated groups 13.65 g/kg and 14.95 g/kg. LPT was increased (P&lt;0.005) in duodenum and jejunum, while in ileum it was insignificant. Total goblet cells count was increased in all duodenum, jejunum and ileum. In duodenum acidic mucin and total GC count was significant (P&lt;0.005) in lysine treated groups at 13.65 g/kg and 11.7 g/kg level while mixed mucin GC count was non-significant. In jejunum and ileum portion acidic mucin, mixed and total GC count was higher (P&lt;0.005) in 13.65 g/kg group. In cecal tonsils length, width, area and number of lymphatic nodule and was significant (P&lt;0.005) in 13.65 g/kg. Lysine supplementation of 13.65 g/kg is beneficial feed additive for Japanese Quails on intestinal morphology

343 Effect of Ruminally-Protected Lysine Supplementation to Limit-fed Growing Cattle on Growth and Subsequent Finishing Performance

Abstract Lysine may be limiting for cattle fed diets based on corn products. Our objective was to supplement ruminally protected lysine to cattle limit-fed a corn-based diet during the growing phase and assess performance during growing and subsequent finishing phases. The 77-d growth trial used 338 crossbred steers allocated to 32 pens limit-fed 2.4% of body weight daily. Steers were implanted (40 mg trenbolone acetate, 8 mg estradiol) at trial initiation. Diets contained 39.5% corn grain, 40% wet corn gluten feed, 13% hay, and 7.5% supplement. Treatments included: no supplemental amino acids (control), 3 g/d metabolizable lysine from Smartamine ML (Adisseo, Alpharetta, GA; Lys-3), 6 g/d metabolizable lysine from Smartamine ML (Lys-6), and supplemental blood meal (Aadvantage; Perdue Agribusiness, Kings Mountain, NC) at 0.89% of dietary dry matter plus 2 g/d metabolizable methionine from Smartamine M (BM). Individual body weights were measured on d 0 and 77. After 77 d, cattle were shipped to a commercial feedlot, commingled in 2 pens, fed a common diet for 185 or 206 d, and slaughtered commercially. Performance during finishing was measured using carcass data from the slaughter facility. During the growing phase, Lys-3 tended to improve average daily gain by 0.11 kg/d (P = 0.12) and feed efficiency (P = 0.08) compared with control. During finishing, Lys-6 tended to have daily gains 0.05 kg/d greater than control and Lys-3 (P = 0.17). Carcass weights were 7.1 and 3.4 kg heavier than control for Lys-6 and Lys-3, respectively. BM did not affect performance during the growing or finishing period and resulting carcass weight. Ruminally protected lysine supplementation during the growing phase tended to improve performance of cattle during growing and/or finishing phases, as well as carcass weights.

Effects of rumen-protected lysine and methionine supplementation in low-crude protein diets on lactation performance, nitrogen metabolism, rumen fermentation, and blood metabolites in Holstein cows

The objective of the study was to investigate the effects of supplementing a low-protein diet with rumen-protected lysine (RP-Lys) and RP-methionine (RP-Met) on milk production, nitrogen metabolism, and rumen fermentation in dairy cows. Forty-eight Holstein dairy cows were blocked by parity (2.1 ± 0.17), milk production (32.1 ± 3.41 kg/d), and days in milk (124 ± 28 d), and randomly assigned to 1 of 4 dietary treatments: control diet (CON, 16 % CP), low-protein diet (LP, 14 % CP, negative control), a moderate diet supplemented with RP-Met (31 g/d) and RP-Lys (MPML, 15 % CP, 110 g/d), and LP diet with RP-Met (50 g/d) and RP-Lys (LPML, 14 % CP, 150 g/d). Dry matter intake (DMI), feed efficiency, and the apparent total tract digestibility of nutrients was not affected by treatments. Compared with the CON, the milk yield was increased in the MPML treatment (P = 0.03) while decreased in the LP treatment (P = 0.02). Milk protein yield in the MPML treatment was higher than that in the other treatments (P < 0.05). The LP, LPML, and MPML treatments had lower concentrations of milk urea-N and plasma urea-N than CON treatments (P < 0.01). The LP, LPML, and MPML treatments decreased the plasma histidine (His) concentration (P < 0.01), while the LP and LPML treatments decreased plasma arginine (Arg) concentration (P < 0.05) compared to the CON treatment. Plasma Met concentration in the MPML treatment was increased (P < 0.01), whereas was decreased in the LP treatment, compared with the CON (P < 0.05). The N intake (g/d) in the LP, LPML, and MPML treatments was lower than that in the CON treatment (P < 0.01), while fecal N (g/d) was not affected by treatments. However, CON treatment increased the urine N (g/d), total excreta N (g/d), N secretion and excretion (g/d), and the proportions of urine N to N intake, whereas decreased the proportion of milk N to N intake and milk N efficiency, compared to the other three treatments (P < 0.01). The rumen concentration of ammonia nitrogen in the LP, LPML, and MPML treatments was lower than that in the CON treatment (P < 0.05). Collectively, the low-protein diets supplemented with RP-Met and RP-Lys could increase milk N efficiency and dramatically decrease urinary N losses. From the perspective of N emission reduction, a 2% reduction in dietary CP was rational.

Salinity levels affect the lysine nutrient requirements and nutrient metabolism of juvenile genetically improved farmed tilapia (Oreochromis niloticus).

This 62-d research aimed to evaluate the effects of dietary lysine levels (DLL) and salinity on growth performance and nutrition metabolism of genetically improved farmed tilapia (GIFT) juveniles (Oreochromis niloticus). Six diets with lysine supplementation (1·34, 1·70, 2·03, 2·41, 2·72 and 3·04 % of DM) were formulated under different cultured salinities in a two-factorial design. The results indicated that supplemental lysine improved the specific growth rate (SGR) and weight gain (WG) and decreased the feed conversion ratio (FCR). Meanwhile, the fish had higher SGR and WG and lower FCR at 8 ‰ salinity. Except for moisture, the whole-body protein, lipid and ash content of GIFT were increased by 8 ‰ salinity, which showed that DLL (1·34 %) increased the whole-body fat content and DLL (2·41 %) increased whole-body protein content. Appropriate DLL up-regulated mRNA levels of protein metabolism-related genes such as target of rapamycin, 4EBP-1 and S6 kinase 1. However, 0 ‰ salinity reduced these protein metabolism-related genes mRNA levels, while proper DLL could improve glycolysis and gluconeogenesis mRNA levels but decrease lipogenesis-related genes mRNA levels in liver. 0 ‰ salinity improved GLUT2, glucokinase and G6 Pase mRNA levels; however, sterol regulatory element-binding protein 1 and fatty acid synthase mRNA levels were higher at 8 ‰ salinity. Moreover, 8 ‰ salinity also increased plasma total protein and cholesterol levels and decreased glucose levels. These results indicated that the recommended range of lysine requirement under different salinity was 2·03-2·20 % (0 ‰) and 2·20-2·41 % (8 ‰) and 8 ‰ salinity resulted in higher lysine requirements due to changes in the related nutrient metabolism, which might provide useful information for designing more effective feed formulations for GIFT cultured in different salinity environment.

Effect of Dietary Lysine and Methionine Supplementation on the Growth and Physiological Responses of Pearlspot Fingerlings, Etroplus suratensis

Background: Successful and sustainable culture of finfish and shellfish depends on the use of nutritionally balanced, low-cost and eco-friendly feeds. This experiment was conducted to evaluate the effect of dietary supplementation of lysine and methionine on the growth and physiological responses of juvenile pearlspot, Etroplus suratensis. Methods: Fingerlings with an average initial body weight of 8.7±0.04 g were distributed to the 300 L FRP tank (n=30 pieces/tank). The pearl spot fingerlings were fed with isonitrogenous (25% Crude protein) feeds supplemented with methionine (1.8, 2.2 and 2.6 g/100 g of diet) and lysine (0.5, 0.9 and 1.3 g/100 g of diet). The growth performance and physiological response of the fishes were assessed. The feeding trial was conducted for a period of 60 days. Result: The methionine supplemented diets at 2.2 g/100 g (T2) and Lysine supplemented diet at 0.9 g/100 g (T5) yielded the best results within the treated groups in terms of average body weight gain, FCR (feed conversion ratio), SGR (specific growth rate), PER (protein efficiency ratio) and FER (feed efficiency ratio). The maximum mean body weight gain recorded in methionine supplemented diet was 20.68±0.20 g in T2 and the maximum mean body weight gain recorded in lysine supplemented diet was 19.6±0.15 g in T5. The mean body weight gain in control was recorded as 12.12±0.20 g. The present study revealed that methionine incorporation at 2.2 g/100 g (T2) and lysine incorporation at 0.9 g/100 g (T5) resulted in better growth performance of the pearl spot Etroplus suratensis fingerlings. Results of challenge tests confirmed that V. anguillarum could act as a primary pathogen for pearlspot reared in freshwater. In the present study, the Hb, RBC, MCV, MCH and MCHC were also affected by dietary methionine and lysine supplementation and were found significantly (p less than 0 .05) higher in fish fed methionine at 2.2% and lysine at 0.9% of diet, indicating that dietary methionine and lysine supplementation activates immune response and promotes fish health. Second-order polynomial regression analysis of weight gain against dietary methionine and lysine levels indicated that the optimum dietary methionine and lysine requirement for maximum growth and feed utilization of pearlspot fingerlings was methionine at 2.2% and lysine at 0.9%.