Lysine requirement for maintenance in growing pigs

Probably due to methodological problems the knowledge about the AA requirement for maintenance in pigs is rather scarce. In the present study an alternative experimental approach was applied and its underlying hypothesis was tested, whether protein retention decreases with body weight (BW), when daily lysine intake remains constant and acts as the limiting factor for protein retention, and whether this decrease reflects the increasing requirement of lysine for maintenance. If this hypothesis can be confirmed, lysine requirement for maintenance can be calculated when assuming a certain value for lysine concentration in body protein, since marginal efficiency of dietary lysine utilisation for protein retention is not affected by its level of intake (when being below the level necessary for maximum response), BW, protein retention capacity of the animal nor by energy intake. A series of N balances experiments using twelve castrated male pigs were performed at approximately 35, 55, 80, 110, and 140 kg of BW and body composition was determined by the D₂O dilution technique. Two lysine intake levels were tested to prove that the animals on the lower level respond to additional lysine and, therefore, have received a lysine-limiting diet, the prerequisite for the alternative. Based on the extent of the decrease in protein retention with BW the following estimates for the maintenance lysine requirement were derived: 18 mg/kg BW, 71 mg/kg BW^0.75, 29 mg/kg fat free substance, and 121 mg/kg body protein. These estimates are higher than values reported in the literature, which might be caused by methodological differences or by the higher feed intake of the animals in the present study.     

The efficiency of and requirements for selected amino acids in growing female pigs. 3. Threonine

With the help of an N utilization model by Gebhardt (1963) and its further development the threonine efficiency coefficients (kThr) of wheat, barley, maize, rye and peanut oil meal of different charges with a supply of L-lysine monohydrochloride, DL-methionine and DL-tryptophan was ascertained with a total of 59 female pigs of the local breed (35-45 kg live weight) by means of an N balance method. The variation range of kThr was between 0.61 and 0.87 based on a threonine effectivity of wheat gluten with lysine as standard. The derived threonine requirement for 100 g daily protein retention with a live weight of 40 kg was ascertained as 6.9 g (kThr = 1) and 9.6 kg (kThr = 0.71 as mean values of the protein sources studied). The proof of threonine limitation in the protein sources was provided by the supplementation of DL threonine.     

Activity and requirement of selected amino acids in growing female pigs. 4. Combination of protein sources with lysine, methionine/cystine and threonine limitation

On the basis of the results of 3 previous articles on the efficiency of amino acids in single protein sources a total of 16 protein sources was tested maintaining the limitation relations of the combination partners with regard to the additivity of the efficiencies of lysine, methionine/cystine and threonine. The results of the N metabolism measurements with a total of 60 female pigs of the country breed type (30...55 kg live weight) allow the conclusion that additive relations and thus suitable correction possibilities exist for the gross amino acid content through the amino acid efficiency for the calculation of requirement and requirement meeting. The N utilization model used (GEBHARDT 1963) is in its further development confirmed as the basis of amino acid efficiency.     

生长肥育猪可消化赖氨酸需要量研究

试验选用80头体重为40 kg左右的杜×(长×大)三元杂交猪,随机分为5个处理,每处理公、母各半,分别饲喂可消化赖氨酸水平为0.59%、0.67%、0.75%、0.83%、0.91%的等能(14.21 M J/kg)、等氨基酸模式的玉米-豆粕型日粮。通过对生产性能和血液生化指标的研究,来确定生长肥育猪可消化赖氨酸需要量。结果表明,当可消化赖氨酸水平为0.75%时,平均日增重、谷草转氨酶活性最高,差异显著(P<0.05);料重比最低,差异显著(P<0.05);血清尿素氮浓度最低,差异极显著(P<0.01)。可消化赖氨酸的不同水平对血清中甘油三酯、总蛋白、白蛋白浓度以及谷丙转氨酶活性没有影响,差异均不显著(P>0.05)。上述结果提示,40~70 kg生长猪的可消化赖氨酸和总赖氨酸需求参数分别为0.75%、0.84%。     

Absorption and utilization of amino acids infused into the cecum of growing pigs. 1. Measurement of N-balance for utilization of lysine and isoleucine; isoleucine requirement for growing pigs

In N-balance experiments with growing pigs (40-60 kg live weight) investigations were made whether lysine or isoleucine that is infused into the caecum can be absorbed there and to what extent these amino acids in that case can be utilised by the animal for protein synthesis. The pigs either received basic rations with insufficient lysine or isoleucine resp. (negative control group) or the amounts of lysine and isoleucine lacking to meet the requirement were supplemented with the feed (positive control group) or continuously infused into the caecum with the help of caecal infusion cannulae (test group). In the experiments with lysine the animals in the negative control group and in the test group showed considerably lower N-balances than the positive control group. There were no differences as regards the apparent digestibility of lysine between the positive control group and the test group. The urine of the test group contained distinctly more NH3. This shows clearly that lysine that is infused into the caecum cannot be utilised by the pigs, it is, on the contrary, microbially decomposed, the nitrogen is chiefly absorbed as NH3 and excreted in urine. As regards isoleucine, the deficit brought about with the basic ration was insufficient in order to achieve significant differences between the N-balance values of the groups so that unambiguous statements on the absorption and utilisation of isoleucine infused into the caecum cannot be made. Concerning apparent digestibility of isoleucine and the NH3 content of the urine, the results of the isoleucine experiments were similar to those in the lysine experiments. According to our N-balance experiments the isoleucine requirement of pigs indicated in relevant literature as 5.6 g/kg dry matter of the feed is by far too high. It should be limited to 3.5 or a maximum of 4.0 g isoleucine per kg dry matter of the feed.     

The activity of and requirements for selected amino acids in growing female swine. 2. Methionine and cystine

The methionine/cystine efficiency of ten protein sources including that of different charges of the same protein source was ascertained in N balance experiments with a total of 60 female pigs in the live weight range of 35-50 kg. The variability of the derived sulfur amino acids (SAS) efficiency coefficient (Csas) ranged between 0.64... 0.91 based on the SAS efficiency of casein as a standard. There was an analogous differentiation for the derived requirement values on the basis of the analysed methionine/cystine values of the proteins. For a protein retention of 100 g/day and a live weight of 40 kg, 6.2g methionine/cystine was ascertained based on the highest SAS efficiency (Csas = 1) as yet.     

Lysine requirement of growing steers

Eight Limousin-cross steers (355 kg) were used in a replicated 4 x 4 Latin-square designed to estimate lysine requirements. Steers were fed a semipurified diet containing little ruminal escape protein. Treatments were abomasal infusions of 0, 8, 16, or 24 g/day L-lysine. All steers were additionally infused with 400 g/day dextrose and 285.9 g/day of an amino acid mix that contained (g/day) L-methionine (12.0), L-histidine (8.1), L-arginine (10.5), L-threonine (12.0), L-valine (18.0), L-isoleucine (13.8), L-leucine (27.3), L-phenylalanine (28.2), L-glutamic acid (76.5), glycine (76.5) and L-tryptophan (3.0); it had been demonstrated previously that when lysine was included in this infusion mixture, nutritional requirements of steers for maximal N retention were met or exceeded. Nitrogen retention averaged 38 g/day and was not affected by treatment, implying that the lysine requirement of steers was less than the 37.8 g/day lysine estimated to be absorbed from the small intestine when the basal diet was fed.     

Lysine requirement of growing male Pekin ducks

1. One growth experiment and one balance test were conducted to study the response to increasing levels of dietary lysine supplementation in male Pekin ducks with special reference to the growth periods from 1 to 3 weeks and 4 to 7 weeks of age. 2. Two different low-lysine diets were used as basal diets in both periods. The basal lysine levels were 7.6 g/kg (d 1 to 21) and 6.2 g/kg (d 22 to 49) and the ranges in lysine concentration were 7.6 to 12.6 g/kg (d 1 to 21) and 6.2 to 11.2 g/kg (d 22 to 49). 3. Growth performance, feed conversion efficiency and meat yield increased ( P < 0.05) with increas6 ing lysine concentration (requirement defined as 95% of the asymptote). 4. It is concluded that the dietary lysine concentration should be 0.93 g/MJ nitrogen corrected apparent metabolisable energy (AME N ) (11.7 g/kg) for the starter period (until d 21) and 0.75 g/MJ AME N (10.0 g/kg) for the grower period (from d 22 onwards).     

The effectiveness of and requirements for selected amino acids in growing female swine. 6. Summarizing discussion, evaluation and recommendations for use of the method presented

Physiologically based statements on the effectivity of lysine, methionine/cystine and threonine of protein sources as well as on the requirement of these amino acids depending on performance were derived on the basis of a total of 568 N balance measurings at growing female fattening pigs in the live weight range between 30 and 50 kg (Liebert, 1986) with the application of the N utilization model by Gebhardt (1963) as well as of particular further developments by the linking of N utilization and the utilization of the respective limiting amino acid. By means of combining protein sources with known amino acid effectivity, the additivity principle for content values of effective amino acid in the feed protein (c.k) suggested as criteria was verified. On the whole, it could thus be proved that the suggested method can decisively contribute to the elaboration of a closed system of quality assessment and requirement assessment depending on performance as well as of supply covering requirements of growing pigs. The advantages in particular over the 'slope ratio' method are emphasized.     

氨基酸蛋白粉替代鱼粉对生长畜肥猪的影响

选用45日龄、体质量相近、健康的杜×长×大三元杂交猪125头,研究氨基酸蛋白粉替代鱼粉对生长育肥猪生长性能及饲养成本的影响.研究结果表明,氨基酸蛋白粉与鱼粉在设定的范围内(3%)对生长育肥猪生长性能的影响差异不显著,即添加一定比例的氨基酸蛋白粉或鱼粉(1%～3%)均可显著提高生长育肥猪的生长性能,添加氨基酸蛋白粉和鱼粉均可显著降低饲养成本(P＜0.05);在第二阶段添加3%的氨基酸蛋白粉替代鱼粉可以降低饲养成本.     

Apparent digestibility of nitrogen and amino acids in protein feedstuffs by growing pigs

Eight digestion trials were conducted with pigs fitted with ileal T-cannulas to determine the apparent digestibilities of N and amino acids in common protein feedstuffs. Trial-to-trial variation was minimal as determined by the variation in digestibilities for soybean meal, which was evaluated in each trial. Apparent digestibilities varied widely; ileal N digestibility ranged from 88 to 63%, and ileal lysine digestibility ranged from 93 to 40%. In general, ring-dried blood meal, corn gluten meal, Menhaden fish meal, poultry-by-product meal and extruded whole soybeans were the most digestible, followed by canola meal, sunflower meal, peanut meal and meat and bone meal. Cottonseed meal and feather meal were the least digestible. Mean values for each feedstuff agree well with published data. Variation in digestibilities among samples of the same feedstuff was greater for the meat and bone meals. Regression of ileal essential amino acid digestibilities on ileal and fecal N digestibility indicated that amino acid digestibilities can be predicted more precisely from ileal N digestibility than from fecal N digestibility. However, neither ileal nor fecal N digestibility could be used with a high degree of certainty to predict ileal amino acid digestibilities.     

Effect of the ratio between essential and nonessential amino acids in the diet on utilization of nitrogen and amino acids by growing pigs.

In 36 growing pigs (30 to 60 kg), N balance and amino acid (AA) composition of weight gain were measured to evaluate the interactive effect of the ratio between N from essential amino acids (EAA(N)) to nonessential amino acids (NEAA(N)) and total N level (T(N)) in the diet on N retention and utilization of N, EAA(N), NEAA(N), and AA. Nine diets composed from ordinary feedstuffs and supplemented with crystalline AA were used (three EAA(N):NEAA(N) ratios of 38:62, 50:50, and 62:38 at three T(N) levels of 18.8, 22.9, and 30.0 g/kg). Pigs were fed restrictedly, at a level of 2.8 x energy for maintenance. In all diets, EAA (including arginine) supply was according to or slightly above the recommended ratios to lysine. Measurements were done in four blocks of nine pigs each. In a concomitant slaughter experiment, the AA composition of deposited body protein was determined to estimate AA utilization. The effects of T(N) and EAA(N):NEAA(N) and their interaction for N retention and utilization were significant. Nitrogen retention increased with higher T(N) in the diet. Increasing EAA(N):NEAA(N) from 38:62 to 50:50 improved N retention only at the two lower T(N) levels. Increasing EAA(N): NEAA(N) above 50:50 failed to improve N retention significantly at any of the three T(N) levels. Lowering T(N) improved the utilization of total and digested N and of EAA(N) and NEAA(N). The increase in EAA(N): NEAA(N) consistently resulted in a lower utilization of EAA(N), but this was compensated by a higher utilization of NEAA(N). The utilization of T(N) was improved by increasing EAA(N):NEAA(N) from 38:62 to 50:50 at the two lower T(N) levels and was relatively unaffected by EAA(N):NEAA(N) at the highest T(N). However, a lower utilization of N was observed at a ratio of 62:38 at a T(N) level of 22.9 g/kg. The effects were similar for utilization of individual EAA and NEAA. Utilization of alanine, aspartic acid, and glycine was close to or >100% at the highest EAA(N):NEAA(N), which was expected because all of these AA are synthesized in pigs. Also, the utilization of arginine was >100% in most of the treatments, which confirms the semiessential character of this AA for maintenance. We concluded that the required ratio of EAA(N):NEAA(N) for optimal N retention and utilization is approximately 50:50. The EAA(N):NEAA(N) is more important at lower dietary protein levels. This study indicates that EAA(N): NEAA(N) can be increased up to 70:30 without lowering the utilization of N. Thus, deaminated EAA(N) was efficiently utilized for the synthesis of NEAA(N).     

生长肥育猪可消化色氨酸需求参数研究

色氨酸（Trp）往往是猪饲粮的第二或第三限制性氨基酸,Trp不足可影响5-羟色胺的代谢,降低猪的生产性能。国外饲养标准对猪Trp的推荐量差异很大,而且大部分没有可消化的需求参数。中国瘦肉型猪饲养标准（1987）未列出Trp需要量的数据,我国至今也未有对生长-肥育猪Trp需求参数的研究报道。本试验旨在研究饲粮色氨酸水平对生长-肥育猪生产性能和血清尿素氮浓度的影响,以探讨生长-肥育猪可消化Trp的需求参数。     

鲁梅克斯K-1草粉猪氨基酸回肠真消化率的测定

选用8头平均体重为(35.5±1.5)kg去势公猪(约克夏×长白×北京黑),分别在回肠末端安装简单T型瘘管,待恢复10d后,挑选其中恢复良好的5头猪,根据5×5拉丁方设计,分别饲喂5种以玉米淀粉为基础配制成的半纯合日粮。其中4种玉米淀粉—豆粕型日粮分别包括39.0%,37.1%,35.1%和31.2%的豆粕及0,5%,10%和20%的鲁梅克斯K-1草粉。第5种日粮为酪蛋白日粮,用于测定内源氨基酸的排出量。分别采用差减法和回归法比较测定了鲁梅克斯K-1草粉氨基酸回肠真消化率。结果表明,随着日粮中鲁梅克斯K-1草粉含量的增加,除组氨酸、缬氨酸和丙氨酸外,其它氨基酸及粗蛋白质的回肠真消化率均显著降低(P<0.05)。当利用差减法测定鲁梅克斯K-1草粉的氨基酸消化率时,其可靠性随着鲁梅克斯K-1草粉在日粮中比例的提高而提高,当鲁梅克斯K-1草粉在日粮中的含量较高时(20%的鲁梅克斯K-1草粉),利用差减法和回归法测得鲁梅克斯K-1草粉粗蛋白质或氨基酸的回肠真消化率没有显著差异。     

Lysine requirement of fattening boars in respect to their performance. 1. Influence of the consumption of energy and amino acids on the fattening performance

With a total number of 157 boars 9 feeding variants with different levels of energy and amino acids were checked. The weight increase per fattening day and the energy and lysine expenditure per kg live weight increase were determined. The insufficient supply with lysine had negative effects on the live weight increase and the energy expenditure during the whole fattening period. Between the variantes with a high supply with amino acids (120%) and the supply according to standard (100%) no significant differences concerning the live weight increase could be ascertained up to 90 kg live weight. Between 90 and 120 kg live weight the animals in the variant with medium energy level and 120% lysine supply achieved significantly higher increases than those in the standard variant. Up to 90 kg live weight the energy expenditure for all groups amounted to 2,08 kEFs (energetic feed units for pigs) per kg live weight increase. The most suitable results were achieved by the animals which received the variants rich in energy (1,760 resp. 1,770 kEFs per kg live weight increase). Above the 90 kg live weight limit the energy expenditure rose considerably, remained however under 2,000 kEFs per kg live weight increase for the boars of the variant with medium energy level and 120% lysine supply as well as for the variant rich in energy and 100% lysine supply. The lysine expenditure in the first variant amounted to 25.1 g per kg live weight increase and for the variant rich in energy to 20.6 g lysine per kEFs.     

Some effects of protein deficiency in young growing pigs. II. Blood plasma free amino acids

The influence of protein deficiency, rehabilitation and total starvation on the free amino acid levels in the blood plasma of pigs has been investigated. It was found that the concentration of most amino acids was reduced during protein deficiency. The levels of leucine, isoleucine and valine were diminished by the greatest proportion, followed by threonine, tyrosine and citrulline. During the first few weeks of protein deficiency the levels of lysine, histidine and arginine were slightly increased, but later decreased below control values. Concentrations of glycine and alanine were altered in a similar way except that the initial increase was much more pronounced. The concentrations of most of these amino acids returned to control levels after rehabilitation. Total starvation led to an increase in concentration of leucine, isoleucine, valine, threonine and to a smaller extent phenylalanine, lysine, citrulline and arginine. The concentration of glycine, alanine and glutamic acid were very much reduced. The level of urea in the circulation dropped reversibly during protein deficiency and increased very much during total starvation.     

Limiting amino acids in an 11% crude protein corn-soybean meal diet for growing pigs

Three experiments were conducted to test the hypothesis that methionine, isoleucine, valine or nitrogen either singly or in combination are limiting in an 11% crude protein, lysine-tryptophan-threonine-supplemented, corn-soybean meal diet for growing pigs. A 16% crude protein diet was used as a positive control in each experiment and all amino acid additions were made, at a minimum, to equal requirements. Average initial weights were 21.3 kg, 23.0 kg and 19.1 kg in Exp. 1, 2 and 3, respectively. The experiments averaged 4 wk in duration. In Exp. 1 and 2, neither the addition of glutamic acid as a source of nitrogen, nor methionine to the 11% diet resulted in any improvement (P greater than .20) in rate or efficiency of growth. Addition of the combination of isoleucine and valine to the 11% diet resulted in an increase (P less than .05) in both growth rate and feed efficiency to a level not different (P greater than .20) from that of the pigs consuming the positive control diet. The addition of valine to the 11% crude protein diet with supplemental lysine, tryptophan and threonine (Exp. 3) caused an improvement in daily gain (P less than .05) but not feed efficiency (P greater than .10). Isoleucine addition tended to reduce pig performance. The results of these experiments suggest that an 11% crude protein, corn-soybean meal diet fortified with lysine, tryptophan and threonine is not limiting in sulfur amino acids or nitrogen. Valine may be the only limiting amino acid.     

Effect of dietary excess of branched‐chain amino acids on performance and serum concentrations of amino acids in growing pigs

Depressed performance and availability of some amino acids (AA) in pigs fed excess Leu diets appear to be related to lower feed intake. Surplus Ile and Val may help to overcome this effect. An experiment was conducted with 24 pigs (31.8 ± 1.2 kg initial BW) to evaluate the effect of dietary excess of either Leu alone or with surplus Ile and Val on performance and serum concentration (SC) of essential AA. Treatments were as follows: T1, basal diet; T2, basal plus 0.43% L‐Leu (excess Leu); T3, basal added with 0.43% L‐Leu, plus 0.20% L‐Ile and 0.25% L‐Val (excess LIV). The basal diet was formulated to contain 0.90% standardized ileal digestible Lys and added with crystalline L‐Lys, L‐Thr, DL‐Met, L‐Trp, L‐Leu, L‐Ile, L‐His and L‐Val to create essential AA:Lys ratios close to an ideal protein for growing pigs. All pigs were fed the same amount of feed twice a day (average, 3.42× the requirement of NEm). Blood samples were collected at 2.5 (absorptive) and 11.0 h (post‐absorptive) post‐prandial to analyse SC of AA. Excess of either Leu or LIV did not affect growth rate nor feed conversion. Excess Leu increased Leu SC and decreased Ile and Val SC (p < 0.05) at both absorptive and post‐absorptive phases, but excess LIV restored the SC of Ile and Val. The SC of other essential AA was not affected by excess of either Leu or LIV. The SC of all AA during absorptive, on average, was about two times higher than that of post‐absorptive phase. These results suggest that the reduced availability (SC) of Ile and Val in pigs consuming excess Leu diets is attributed to a reduced absorption and increased cellular degradation rates of them.