Effects of Lower Dietary Lysine and Energy Content on Carcass Characteristics and Meat Quality in Growing-finishing Pigs

An experiment was performed to evaluate the effects of dietary metabolizable energy (ME) and lysine on carcass characteristics and meat quality in Arbor Acres (AA) broilers from 1 to 56 days of age. A total of 2,970 1-d-old male broiler chicks were randomly allocated to nine dietary treatments (three ME levels in combination with three lysine levels), and dietary ME and lysine concentrations were formulated by varying corn, soybean meal, tallow, and L-lysine sulfate concentrations. Live body weight (BW), carcass weight (CW), dressing percent, breast muscle weight (BMW), yield of breast muscle, muscle color (CIE L*, a*, and b*), pH values 45 min and 24 h postmortem (pH 45 , and pH 24 ), meat shear force value (SFV), and water loss rate (WLR) were evaluated. Results showed that live body weight and dressing percent increased (p<0.05) as dietary energy increased. Higher dietary lysine content improved breast muscle weight. Neither carcass weight nor yield of breast muscle was affected by dietary energy or lysine content. Higher ME increased the b* value (p = 0.067) and pH 24 value (p<0.05), whereas it decreased SFV (p<0.05) and WLR (p = 0.06). Only water loss rate was influenced (p<0.01) by dietary lysine, which was higher in broilers from the high lysine diet as compared to those from medium or low lysine diets. The pH 45 value and L* value of breast muscle were not affected by ME or lysine. Significant interaction of dietary ME and lysine was found on a* value of breast muscle. These results indicated that dietary ME and lysine had important effects on breast muscle growth and meat quality, however their effects were different. Different concentrations of dietary ME and lysine might be considered to improve meat quality.

Sixty male and 60 female crossbred pigs were allocated to an experiment to investigate the effects of porcine somatotropin (pST) administration (0 or 6 mg/d) and dietary lysine content on growth performance, tissue deposition, and carcass characteristics over the live weight range of 80 to 120 kg. Pigs receiving pST were given diets containing 6.9, 7.8, 8.8, 9.7, 10.6, or 11.5 g lysine/kg, whereas control pigs received diets containing 4.8, 5.8, 6.9, 7.8, 8.8 or 9.7 g lysine/kg. These dietary levels ranged from 0.40 to 0.70 g available lysine/MJ of DE for pST-treated pigs and from 0.28 to 0.58 g available lysine/MJ of DE for control pigs. Pigs were individually housed in pens, and there were five replicates of each treatment. All diets contained 14.5 MJ of DE/kg and were offered for ad libitum consumption to pigs between 80 and 120 kg live weight. Growth rate increased exponentially and food conversion ratio (FCR) decreased exponentially with increasing levels of lysine. In addition, there was a significant sex x pST interaction such that pST reduced the sex difference in FCR. Growth rate was faster in boars than in gilts and was increased by pST at the higher levels of dietary lysine. Similarly, FCR was lower for boars than for gilts and was decreased by pST at the higher dietary lysine levels. The optimum growth rate and FCR were defined as the lysine level at which growth rate and FCR were 95% and 105%, respectively, of the lysine plateau. The optimum growth rate and FCR were achieved at similar dietary lysine contents and were approximately 0.35 and 0.52 g available lysine/MJ of DE for control and pST-treated pigs, respectively. Protein deposition in the carcass increased exponentially with increasing dietary lysine level, was higher in boars than in gilts, and was increased by pST at the higher dietary lysine contents. Sex had no effect on dietary lysine required to maximize protein deposition. The dietary lysine contents required to ensure 95% of plateau protein deposition of 104 and 153 g/d were 0.39 and 0.55 g available lysine/MJ of DE for control and pST-treated pigs, respectively. The increase in lysine requirement with pST seems to be commensurate with the increase in protein deposition.

ABSTRACTThe responses of growing pigs to dietary lysine as influenced by sex (male and female) and cereal (barley and wheat) were investigated in an 8 × 2 × 2 factorial experiment involving 128 pigs. The basal barley-soya bean (13·4 MJ digestible energy (DE) per kg) and wheat-soya bean (14·1 MJ DE per kg) diets were offered ad libitum from 20 to 50 kg live weight. The eight dietary lysine concentrations were 70 to 140 g/kg in increments of 1·0 g/kg. The experiment was repeated with pigs given food according to a restricted scale. Performance in both experiments was assessed by multiple regression analysis based on data from successive 10-kg live-weight intervals. Analysis of variance was used to assess chemical carcass composition and retention of protein and fat after slaughter at 50 kg live weight.Average daily DE intake (MJ) of pigs fed ad libitum was not significantly different for barley-based (27·4) and wheat-based diets (29·1). For pigs fed on a restricted scale, average daily DE intake was 18 MJ for barley-based and 17·5 MJ for wheat-based diets. The daily energy retained in the empty carcass, expressed as a proportion of daily DE intake, was proportionately 0·08 less for barley-based than for wheat-based diets irrespective of whether food was offered ad libitum (0·347 v. 0·379) or restricted (0·311 v. 0·337).The average daily gain of females fed ad libitum was not affected by dietary lysine concentration. With males, the response of daily gain to lysine concentration was curvilinear, increasing to a maximum of 120 g dietary lysine per kg up to 40·3 kg and 7·0 g/kg at greater weights for both cereals. For pigs fed on a restricted scale the daily gain on barley diets increased linearly up to the maximum dietary lysine concentration (14 g/kg), while for those on wheat-based diets maximum daily gain occurred with a lysine concentration of 11·2 g/kg for males and 131 g/kg for females. Carcass P2 backfat (mean = 15·4 mm), carcass fat proportion (mean = 242 g/kg) and carcass protein retention (mean = 89 g/day) were not significantly affected by dietary lysine concentration from 7 to 14 g/kg when pigs were fed ad libitum. However, when pigs were fed at a restricted level carcass fatness decreased to a minimum at 12 g lysine per kg.

Effect of dietary digestible lysine concentration on performance, egg quality, and blood metabolites in laying hens

Two experiments were conducted to investigate the effects of different breeds and dietary nutrient levels on expressions of paired box (Pax) genes and myogenic regulatory factors (MRFs) in pigs. Thirty Large White (LW) barrows and thirty Chenghua (CH, a native breed of China) barrows were performed in experiment 1. Results exhibited that in the CH pigs the abundances of Pax3 at 105 and 220 d of age, Mrf4 at 63 d of age, Myf5 and Mrf4 at 220 d of age were higher than those in the LW pigs (p < 0.05). Meanwhile, the expressions of MyHC-І and ІІa in the CH pigs were upregulated, and the abundance of MyHC-ІІb were downregulated compared with those in the LW pigs at 105 and 220 d of age (p < 0.05). Moreover, the meat quality of the CH pigs was better than in the LW pigs (p < 0.05). In experiment 2, sixty LW pigs were randomly assigned to two dietary treatments meeting their nutrient requirements (NRC) or a diet with moderately reduced digestible energy, crude protein and Lys level by 560 kJ/kg, 1.48% and 0.34%, respectively (LOW diet). The results showed that the reduced dietary nutrient level increased (p < 0.05) the expressions of MyoG and Mrf4 at 105 d of age, Pax3, Myf5, and Mrf4 at 220 d of age, and upregulated (p < 0.05) the abundance of MyHC-ІІa at 105 and 220 d of age in LW pigs. In addition, a decrease in dietary nutrient level improved the meat quality in LW pigs (p < 0.05). Collectively, the expressions of Pax genes and MRFs were markedly different between the CH and LW pigs. The CH pigs exhibited higher expression levels of Pax3, Myf5, Mrf4, MyHC-І and ІІa, which may improved the meat quality. A decrease in dietary nutrient level upregulated the abundances Pax3, Mrf4, Myf5, MyoG, and MyHC-ІІa, and might enhance the meat quality in the LW pigs.

This study was designed to investigate the effects of dietary lysine level on the intramuscular fat content of the longissimus in finishing pigs reared at two environmental temperatures. Seventy-two hybrid gilts were individually penned and given ad libitum access to either a diet formulated to meet their lysine requirement (6.4 g/kg lysine) or a lysine-deficient diet (4.8 g/kg). Pigs were held at one of two environmental temperatures (thermoneutral [18 degrees C] or hot [32 degrees C]). The study was carried out between approximately 90 and 126 kg live weight; pigs in the thermoneutral and hot environments were on test for 5 and 7 wk, respectively. There were no interactions between dietary lysine level and environmental temperature. Dietary lysine content did not influence feed intake or average daily gain; however, pigs on the lysine-deficient diet had a poorer gain:feed ratio than those fed to requirement (P < .01). High environmental temperature decreased feed intake (P < .001) and average daily gain (P < .01) but improved gain:feed ratio (P < .01). Backfat at the 10th rib was increased and loin eye area and estimated percentage lean in the carcass were decreased for pigs on the lysine-deficient diet. The higher environmental temperature resulted in an increase in carcass length but had no effect on other carcass measurements or intramuscular fat. Feeding the lysine-deficient diet resulted in an increase of .55 percentage unit in longissimus intramuscular fat content (P < .01); however, there was no difference in subjective marbling scores between the diets. Warner-Bratzler shear force values were not affected by dietary lysine level or environmental temperature. Results from this study suggest that feeding of lysine-deficient diets at the end of the finishing period can increase intramuscular fat deposition under thermoneutral and hot conditions.

Two experiments were conducted to determine the effects of different dietary lysine levels on the apparent nutrient digestibility, the serum amino acid (AA) concentration, and the biochemical parameters of the precaval and portal vein blood in growing pigs. In Experiment 1, 15 noncannulated pigs received diets with different lysine densities (0.65%, 0.95%, and 1.25% lysine) for 13 d. A total collection digestion test was performed, and blood samples were collected from the precaval vein at the end of the experiment. In Experiment 2, four cannulated pigs were fed the same diets of Experiment 1. The experiment used a self-control experimental design and was divided into three periods. On d 5 of each period, at 0.5 h before feeding and hourly up to 8 h after feeding, single blood samples were collected from catheters placed in the portal vein. In Experiment 1, some serum AAs (including lysine), serum urinary nitrogen (SUN), and total protein (TP) concentrations were significantly affected by the dietary lysine levels (p<0.05). Moreover, the 0.65% lysine treatment showed a significant lower apparent digestibility of gross energy, dry matter, crude protein, and phosphorus than the other treatments (p<0.05). In Experiment 2, serum lysine, histidine, phenylalanine, threonine, valine, isoleucine (p = 0.0588), triglyceride, and SUN (p = 0.0572) concentrations were significantly affected by the dietary lysine levels (p<0.05). Additionally, almost all of the determined serum AA and total AA concentrations reached their lowest values at 0.5 h before feeding and their highest values at 2 h after feeding (p<0.05). These findings indicate that the greatest absorption of AA occurred at 2 h after feeding and that the dynamic profile of serum AA is affected by the dietary lysine levels. Moreover, when the dietary lysine content was 0.95%, the growing pigs achieved a better nutrient digestibility and serum metabolites levels.

Simple SummaryWith the increasing demand for aquaculture, the resource of high-quality traditional protein (such as fishmeal) becomes limited, and plant ingredients are often used as substitutes for fishmeal because of their low price and wide availability. However, plant proteins are usually deficient in certain essential amino acids (EAAs), which adversely affects the growth performance of aquatic animals. Lysine is generally the first limiting amino acid in plant protein ingredients used to formulate the aquafeed, and it plays an important role in physiological processes including antioxidant, differentiation, growth, immunity, and reduction of nitrogen emission. In this study, the effects of dietary graded L-lysine concentrations on the growth, proximate composition, and AA (amino acid) profile of coho salmon alevins were evaluated by a feeding trial. The results showed that an adequate dietary lysine level significantly improved the specific growth rate (SGR), protein efficiency ratio (PER), body protein deposition (BPD), and feed conversion ratio (FCR). The dietary optimum L-lysine requirements for coho salmon alevins were 3.74%, 3.73%, 3.91%, and 3.77% of the diet or 6.80%, 6.78%, 7.11%, and 6.85% of dietary proteins against the SGR, PER, BPD, and FCR, respectively.The suitable dietary L-lysine concentration for coho salmon (Oncorhynchus kisutch) alevins was assessed by a dose response feeding trial. Six experimental diets were made with graded L-lysine concentrations of 2.29%, 2.81%, 3.32%, 3.80%, 4.27%, and 4.78% of the dry matter, respectively, each of which was fed to triplicate groups of 100 alevins (initial body weight: 0.30 ± 0.01 g) in 18 plastic baskets (water volume 240 L). The alevins were cultured in a flowing freshwater system and fed manually to apparent satiation four times a day for 12 weeks. The survival rate of alevins did not differ significantly among the dietary groups. The specific growth rate (SGR), protein efficiency ratio (PER), and body protein deposition (BPD) increased significantly (p < 0.05) with the increase in dietary lysine concentration up to 3.80% and then reduced as lysine level further increased. The feed conversion ratio (FCR) had an inverse trend to SGR. The whole-body crude protein content of the alevins increased significantly with increasing dietary lysine level, while crude lipid content showed the opposite trend. In comparison, the contents of morphological indices, whole-body moisture, and ash were not affected significantly (p > 0.05) by the different dietary lysine concentrations. The highest contents of lysine, arginine, and total essential amino acids (EAAs) were observed in the group with 4.27% dietary lysine concentration, which did not differ significantly from those in the 3.32%, 3.80%, and 4.78% groups but was significantly higher than those in the 2.29% and 2.81% groups. Similarly, valine had the highest content in the group with 4.78%. The variations in dietary lysine had no significant impacts on other EAA and non-EAA contents except glycine, which increased with increasing dietary lysine level. Second-order polynomial model analyses based on SGR, PER, BPD, and FCR evaluated the optimum L-lysine requirements of coho salmon alevins as 3.74%, 3.73%, 3.91%, and 3.77% of the diet or 6.80%, 6.78%, 7.11%, and 6.85% of dietary proteins, respectively.

Economically optimal dietary crude protein and lysine levels for starting broiler chicks

This study aimed to investigate the effects of dietary crude protein (CP) and lysine levels on growth performance, slaughter performance, meat quality, and myofiber characteristics of slow-growing chicken. A 3 × 3 factorial experiment was arranged, and the chickens were fed with 3 levels of dietary CP (16.0%, 17.0%, 18.0%) and 3 levels of dietary lysine (0.69%, 0.84%, 0.99%). A total of 540 8-week-old Beijing-You Chicken (BYC) female growing chickens were randomly allocated to 9 groups, 5 replicates per group, and 12 chickens per replicate. The birds were randomly allocated to one of the 9 experimental diets. Growth performance, slaughter performance, meat quality, and myofiber characteristics were determined at 16 weeks of age. The results showed that dietary CP level and the interaction of dietary CP and lysine levels affected average feed intake (AFI) (p < 0.05). The AFI in the 16.0% CP and 17.0% CP groups was higher than in the 18.0% CP group (p < 0.05). Dietary CP levels significantly affected body weight gain (BWG) (p < 0.05) at 9 to 16 weeks. The 18.0% CP group had the highest BWG (93.99 g). Dietary CP levels affected the percentage of leg muscle yield, and the percentage of leg muscle yield of the 16.0% CP group was significantly lower than that in the other two groups (p < 0.05). Dietary CP and lysine levels alone and their interactions did not affect pH24h, drip loss, and cooking loss of breast muscle (p > 0.05). The shear force of the 18.0% CP group (29.55 N) was higher than that in the other two groups (p < 0.01). Dietary CP level affected myofiber characteristic (p < 0.01), with the lowest myofiber density (846.35 p·mm-2) and the largest myofiber diameter (30.92 μm) at 18.0% CP level. Dietary lysine level affected myofiber diameter, endomysium thickness, perimysium thickness (p < 0.01), with the largest myofiber diameter (29.29 μm) obtained at 0.84% lysine level, the largest endomysium thickness (4.58 μm) at 0.69% lysine level, and the largest perimysium thickness (9.26 μm) at 0.99% lysine level. Myofiber density was negatively correlated with myofiber diameter and endomysium thickness (R = -0.883, R = -0.523, p < 0.01); perimysium thickness had a significant negative correlation with shear force (R = -0.682, p < 0.05). Therefore, reducing dietary CP level and adding appropriate lysine can reduce myofiber diameter and increase perimysium thickness, reducing shear force and improving meat tenderness. A high lysine level (0.99%) in the low-CP (16.0%) diet can improve meat tenderness by regulating the myofiber characteristic without affecting production performance.

We conducted a series of investigations in order to elucidate role of nutritional status in regulating GLUT expression and energy metabolism in porcine muscle. Firstly, the role of mild undernutrition in regulating muscle GLUT gene expression and function was studied in growing pigs (3 wk of age) on a high (H) or low (L) food intake (H = 2L) at 35°C or 26°C. Low food intake selectively upregulates GLUT1 and GLUT4 gene expression; mRNA levels were elevated in longissimus dorsi (L. dorsi) and rhomboideus muscles but not in diaphragm or cardiac muscles. Our next step was to determine whether dietary lysine, a major primary limiting amino acid in diets for pigs, affects muscle GLUT4 expression. Pigs of 6 wk of age were pair-fed a control or low lysine (LL) diet. The control diet contained optimal amounts of all essential amino acids, including 1.15% lysine. The LL diet was similar but contained only 0.70% lysine. GLUT4 mRNA expression was upregulated by the LL diet in L. dorsi and rhomboideus muscles, whereas that in cardiac muscle was unaffected. GLUT4 protein abundance was also higher in rhomboideus muscle of animals on the LL diet. We conducted another investigation in order to elucidate effects of the LL diet on post-GLUT4 glucose metabolism. Activity of hexokinase was unaffected by dietary lysine levels while that of citrate synthase was higher both in L. dorsi and rhomboideus muscles of pigs fed on the LL diet. Glucose 6-phosphate content was higher in L. dorsi msucle in the LL group. Glycogen content was higher both in L. dorsi and rhomboideus muscles in the LL group. Further, we determined the effects of dietary lysine levels on accumulation of intramuscular fat (IMF) in L. dorsi muscle of finishing pigs. A low lysine diet (lysine content was 0.40%) meeting approximately 70% of the requirement of lysine was given to finishing pigs for two months. IMF contents in L. dorsi of the pigs given the low lysine diet were twice higher than those of the pigs fed on a control diet (lysine content was 0.65%). Finally, we proved that a well known effect of breadcrumbs feeding to enhance IMF of finishing pigs could be attributed to shortage of amino acids in diets including breadcrumbs.

To elucidate the effect of early life dietary nutrient level and vitamin D source during gilt development on progeny growth performance, equal number of weaning age piglets (n = 72) were selected from each of 4 sow treatments group. All pigs were fed a common 3,000 ppm zinc diet for first two weeks postweaning to allow for accommodating the weaning process. At the beginning of week 3, pigs were sorted by sow parity and BW within gender and stratified based on maternal dietary treatments. Dietary treatments during gilt development period included two levels of dietary nutrients (Adeq: optimal growing diet that exceed NRC 2012 recommendation or Low: moderate slow growing diet that SID lys and ME levels were gradually reduced by 0.03% and 0 kcal/kg, 0.15% and 146 kcal/kg, and 0.15% and 150 kcal/kg, respectively) and two sources of vitamin D [StD: 1653 IU cholecalciferol/kg or HyD: 500 IU cholecalciferol/kg + 50 mcg calcifediol (ROVIMIX HY.D DSM Nutritional Products North America)] during development phase 1 (23 to 57 kg), 2 (57 to 91 kg), and 3 (91 until breeding). Dietary nutrient level treatment was withdrawn during gestation and lactation stages, while sows remained on their vitamin D treatments. Progeny were fed with a 6-phase feeding regimen as nursery phase 3 (14 d) and 4 (14 d), grower phase 1 (28 d) and 2 (28 d), and finisher phase 1 (28 d) and 2 (28 d). All pigs were transferred to a commercial processing plant where carcass characteristics were measured. Data were analyzed using Mixed procedure of SAS (Cary, NC) with maternal diet nutrient level, vitamin D source and the interaction as fixed effects. Progeny born from sows fed HyD diets had greater ADG in overall grower/finisher phases (P = 0.04) and during the whole trial (P = 0.03). This weight gain improvement increased the final BW, HCW, and yield percentage over StD derived progeny by 3.19 kg, 3.56 kg and 0.11% (P = 0.04, 0.02 and &amp;lt; 0.01), respectively. Dietary nutrient level had limited effect on progeny ADG and BW during the preslaughter period. The maternal vitamin D source did not affect progeny ADFI but overall G:F tended (P = 0.06) to be greater in pigs sourced from dams fed HyD . A maternal vitamin D by nutrient level interaction was observed for ADFI during grower/finisher phases (P = 0.05) and overall (P = 0.07) because progeny from gilts fed a low nutrient level had greater intake than cohorts from gilts fed an adequate nutrient diet, while ADFI was similar for all offspring from gilts fed HyD diets. These results indicate that manipulating nutrients during gilt development, or feeding HyD rather than StD to reproducing sows, can affect growth of their progeny to slaughter.

Feeding high leucine levels (2.0 and 3.0% total dietary leucine) to finishing pigs (73 to 127 kg liveweight) increased the intra muscular fat content of the longissimus muscle in pigs fed diets with low lysine levels (0.5% total dietary lysine) but not in animals fed high lysine levels (0.7 %). Key words: Lysine, leucine, growth performance, carcass and meat quality

A total of 1,003 barrows and gilts (PIC 337 × 1050, initially 113.5 lb) were used in an 88-d study to determine effects of various levels of balanced amino acid density on growth performance and carcass characteristics. Balanced amino acid refers to balancing the dietary amino acids according to the ideal protein ratio, at least for the first 4 limiting amino acids; the other amino acids may be at or higher than required levels. In this study, this balance was accomplished by using supplemental amino acids and formulating to meet the first 4 limiting amino acids: lysine, threonine, methionine, and tryptophan. Three experimental diets were tested using 6 replicate gilt and 7 replicate barrow pens per treatment. These diets were tested over 2 different phases, a grower phase (d 0 to 28) and a finishing phase (d 28 to 88). Dietary treatments included a diet that met the NRC (1998)5 requirements, a diet that met Evonik Degussa (Hanau, Germany) requirements, and a diet that was formulated to be 10% greater than Evonik Degussa recommendations. No gender × dietary treatment interactions were observed (P > 0.30) for any of the growth or carcass characteristics. During the growing phase, ADG and F/G improved (linear; P 0.62) in ADG, ADFI, or F/G from increasing dietary lysine or balanced protein levels. Gilts had decreased (P 0.28) for carcass yield, backfat depth, loin depth, percentage lean, live value, or calculated income over feed cost. In this experiment, increasing the amino acid density (dietary lysine level) over the NRC (1998) requirement offered improvements in the grower phase but not the finishing phase.

Dose-dependent response of intramuscular fat accumulation in longissimus dorsi muscle of finishing pigs to dietary lysine levels