太田 能之

The effects of intracerebroventricular injection of L-tryptophan on feeding behavior and the levels of brain neurotransmitters (amino acids or monoamines) were investigated in ad libitum chicks. The tryptophan treatment (3 or 6 mu mol) significantly inhibited food intake in chicks at 30min postinjection. The levels of serotonin (5-HT) and its metabolite, 5-dihydroxyindolacetic acid, in chicks treated with tryptophan were significantly higher than those with saline at 15 min postinjection. However, there were no differences in the levels of catecholamines (adrenaline, noradrenaline and dopamine) and amino acid neurotransmitters (e.g., gamma-aminobutyric acid, glycine and glutamic acid). The tryptophan-induced anorexia tended to be attenuated by the 5-HT2A receptor antagonist ketanserin (10 mu g). These results suggest that the administration of tryptophan into the chick brain produces the anorexic effect, and that the change in brain 5-HT content may be involved in this anorexia.

1. The oral administration of glucose or dietary glucose reduces fasting plasma mannose concentrations in mammals. On the other hand, there have been no reports on plasma mannose levels in birds. We have analysed chicken plasma mannose and glucose by an original high-performance liquid chromatography (HPLC) method, together with plasma non-esterified fatty acid (NEFA) concentrations in chickens. 2. Plasma glucose concentrations of chickens did not differ among three different age groups (0, 18 and 150 d). However, the plasma mannose concentrations of chicks at the age of 0 d were higher than those of chickens at the ages of 18 and 150 d. 3. At the age of 18 and 150 d, plasma glucose concentrations were elevated and plasma mannose and NEFA concentrations were decreased after regular feeding, compared to fasting levels.

Four experiments were conducted to estimate dietary lysine (Lys) requirements using plasma amino acid concentrations as a criterion in mature thoroughbreds. In each experiment four adult thoroughbreds were used. The changes in plasma Lys concentration after feeding were observed in Experiment 1. Blood samples were taken from the cervix vein 0.5 h before, and 1, 3, 5.5, and 10 h after feeding. The plasma Lys concentration increased and remained constant until 3 h after feeding, decreased until 5.5 h and remained constant after then. Therefore, the bleed was done at 3 h after feeding in all later experiments. To make sure of the response speed of the plasma Lys to changes of dietary Lys levels, dietary Lys levels were changed from high to low, and low to high levels in Experiment 2. Blood samples were taken just on the changing day and 1, 2 and 3 days after changing diets. The plasma Lys concentration decreased until 2 days after changing the diet, and then remained constant with advancing days after changing the diet from high Lys to low Lys. On the other hand, the plasma Lys increased until one day after changing the diet, and then remained constant with advancing days after changing dietary Lys levels. Thus, blood samples were taken 3 days after feeding in the next experiments. The possibility of estimating the Lys requirement for maintenance using plasma Lys concentration was elucidated by two methods in Experiments 3 and 4. In Experiment 3, the horses were fed a diet containing 0.33 percent Lys for 3 days. After this the diet was changed to diets containing higher levels of Lys to 0.40, 0.47, 0.54, and 0.61 percent every third day. The Lys requirement was estimated to be 0.46 percent of diet from the response of plasma Lys concentration of five Lys levels. In Experiment 4, a 4 x 4 Latin square design was used for four dietary Lys levels. The Lys requirement was estimated to be 0.47 percent of the diet with a plasma Lys concentration of four Lys levels.

Three experiments were conducted to compare the growth and protein utilization of embryo between broilers and layers. In experiments I and 2, the average weight of eggs was the same for broilers and layers. Nothing or an amino acid (AA) solution was injected into the eggs of broilers at d 7 of incubation, and the plasma AA concentration of newly hatched chicks was determined in broilers in experiment 1. In experiment 2, the same treatments as experiment 1 were used on layer breeder eggs. Plasma Tau, Thr, and Lys concentrations of hatched chicks increased when AA solution was injected in broilers breeder eggs (P < 0.05) but not in layers (P > 0.05). The AA ratio to Lys was reduced by AA injection in broilers but not in layers. In experiment 3, weights of embryos and egg were recorded, and CP contents were analyzed over time during incubation (d 0, 7,14, and 19 of incubation) in broilers and layers using eggs of the same weight. There were no differences in the weights and CP contents of embryos and eggs from broilers and layers. On d 14 and 19 of incubation, weights and CP contents of embryo were higher in broilers than layers (P < 0.05). These results suggested that the egg protein content might be adequate for hatching but insufficient for maximum growth of embryos from broilers.

In order to confirm the usefulness of chromic oxide as an indicator in the determination of digestibility of nutrients in feeds, two experiments were conducted on 4 male thoroughbreds 5 to 9 years old. In Experiment 1, in order to determine the timing of sampling, the time course of fecal chromic oxide after changing feeds and daily variation of the fecal concentration of chromic oxide were observed. Horses were given Feeds 1 and 2 containing 0.2% chromic oxide for 7 days. Feces were collected infeces bags. In Experiment 2, horses were supplied Feeds 1 and 2 for 10 days and feces were collected in the same way as in Experiment 1 for the total feces collection method and about 200 g of feces at 7:00 and 19:00 for the chromic oxide index method for the last 4 days. Fecal contents of chromic oxide reached a plateau at 48 hr after feeding Feeds 1 and 2 containing chromic oxide and remained constant after that. The digestibility of crude protein, ether extract, nitrogen free extract and crude fiber determined by the chromic oxide index method agreed well with that by the total feces collection method in both feeds. Because the timing of excretion of feces was relatively constant in the morning and evening feeding, it was easy to collect feces directly from the anus with a bucket.

In order to formulate feeds for horses, it is necessary to elucidate the content and digestibility of nutrients in feedstuffs and the requirement of nutrients of horses. Preceding the determination of nutrient requirements for the maintenance of thoroughbreds, the digestibility of nutrients of roughages, i.e. timothy, Italian ryegrass and orchardgrass hay, and hay cubes and alfalfa pellets was determined by the total feces collection method. Four male thoroughbreds 5 to 11 years old were supplied 7.8 kg feed daily and half the amounts of the rations were supplied at 8:00 and 17:00 for 10 days. Feces were collected on the last 4 days of each experimental period. Horses were supplied 7 kinds of feeds, basal feed and mixtures of basal feed and timothy, Italian ryegrass or orchardgrass hay or hay, cube or pellet alfalfa at the ratio of 1:1. The basal feed consisted of a commercial horse feed and timothy hay at the ratio of 7:3. There were differences in the content and digestibility of nutrients and calculated nutritive values, digestive crude protein (CP), total digestive nitrogen among three kinds of grass hays, i.e. timothy, Italian ryegrass and orchardgrass, but there were small differences in the above cited values among three types of alfalfa, i.e. hay, cube and pellet. The digestibility of CP increased with increasing dietary CP levels. The endogenous fecal nitrogen was estimated to be 23 g/day. The calculated true digestibility of all feedstuffs differed widely among feedstuffs.

Three experiments were conducted to evaluate the effect of differences in in ovo amino acid (AA) injection sites in broiler breeder eggs on subsequent hatchability and BW of chicks. In Experiment 1, an AA solution was injected into eggs with 13-mm. or 19-mm, 27-ga. needles. Uninjected eggs served as controls. Hatchability was decreased (P < 0.05) in eggs receiving AA injections with the 19-mm needle in comparison to the control and 13-mm-injected groups. However, BW of chicks increased (P < 0.05) relative to pre-incubational egg weight by AA injection with the 13-mm. needle. In order to evaluate the in ovo location of AA injections from Experiment 1, India ink was injected into eggs in Experiment 2 with a 13-or 19-mm needle. Immediately after injection, the air cell end of the egg was windowed in order to observe effects of injection site. Windowing of eggs was accomplished by removing a piece of the eggshell over the air cell and the underlying membrane at Day 7 of incubation. The amount of injected India ink was higher in the extra-embryonic coelom in eggs treated by both needles, However, the occurrence of India ink in the extra embryonic coelom was higher (P < 0.05) in the group injected with AA solution using a 13-mm needle as compared to that after injection using a 19-mm needle. The observation of India ink in the amniotic cavity was higher (P < 0.05) in the group injected with AA solution using a 19-mm needle rather than that using a 13-mm. needle. In Experiment 3, treatments consisted of control (uninjected eggs) or windowed eggs. Windowed eggs received AA to the chorioallantoic membrane, the yolk, extra-embryonic coelom, or amniotic cavity at Day 7 of incubation. Hatchability was reduced, but chicks hatched when eggs were windowed and when AA were injected into the yolk sac or extra-embryonic coelom. However, chicks did not hatch when AA were administered to the chorioallantoic membrane or into the amniotic cavity. These results suggest that the best AA injection sites in ovo may be the yolk and extra-embryonic coelom.

Two experiments were conducted to evaluate the effect of in ovo amino acid (AA) injections in broiler breeder eggs on AA utilization of embryos. All AA used in these experiments were pure crystalline AA in free-base form. Treatments in Experiment 1 comprised 1) control eggs (no injection), 2) 0.5 mL sterile-distilled water injected eggs, and 3) eggs injected with an AA solution suspended in 0.5 mL sterile-distilled water. Injections were administered into the yolk at Day 7 of incubation. At hatch, chicks were killed and bled, and plasma AA concentration was determined. Plasma AA concentration of hatched chicks decreased (P < 0.05) when water was injected. In addition, all AA from eggs injected with AA, except Glu and Lys, were decreased (P < 0.05) at hatch as compared to control eggs. However, AA pattern was not affected by in ovo water injection, but the AA ratio to Lys was reduced by in ovo AA injection. Experiment 2 was conducted to evaluate whole internal egg AA concentrations over incubation time in the presence or absence of in ovo AA administration. Treatments in Experiment 2 comprised 1) control eggs (no injection), and 2) eggs injected with a AA solution at Day 7 of incubation. The AA contents of embryo, yolk, albumen, and allantoic and amnion fluids were analyzed over time during incubation (Days 0, 7, 14, and 19 of incubation). On Day 14 of incubation, there were no differences in AA contents of all tissues between the control group and the group injected with AA on Day 7 of incubation. On Day 19 of incubation, AA contents of embryo, yolk, albumen, and allantoic and amnion fluids were increased (P < 0.05) as mediated by in ovo administration of AA at Day 7 of incubation. These results suggest that in ovo administration of AA may increase AA concentrations in chicken embryos and other egg contents.

It is important to determine the exact amino acid requirements of poultry for effective utilisation of feedstuffs and to reduce nitrogen excretion. However, it is laborious and expensive to determine amino acid requirements in feeding trials. Plasma amino acid concentration responds quickly to changes in dietary amino acid levels and the response is seen for a long period. It is known that amino acid requirements determined by plasma amino acid concentration agree well with those in feeding trials in many species at 2, 4 and 20 days after changing dietary levels. This study was conducted to confirm whether it is possible to predict requirements of several amino acids simultaneously in a short period using plasma amino acid concentration as the parameter. Eight-d-old broiler female chicks were given three diets, in which histidine (His), phenylalamine (Phe) or both amino acids were variables for a 10-d period. The determined requirement for both amino acids by plasma amino acid concentration on day 2 after feeding the experimental diet was higher than that on day 10. These results indicated that amino acid requirements decrease with advancing age. There were no differences in His and Phe requirements from different diets using the same parameters. This indicated that it was possible to predict His and Phe requirements from the diets in which His, Phe or both amino acids were varied. From these results, it was possible to determine multiple amino acids requirements simultaneously over a short period.

血漿遊離アミノ酸濃度は様々な要因の影響を受けるため,アミノ酸要求量を推定する有用な指標として用いるためには,血漿遊離アミノ酸濃度に影響する要因を明らかにする必要がある。本試験では,産卵鶏の主たる8組織の遊離アミノ酸および蛋白態のアミノ酸濃度を調べた。40週齢の産卵鶏にCP 16.6%, ME 2.90kcal ME/kgの試験飼料を給与した。当日産卵し,次日も産卵が期待される10羽に,放卵5時間後にネンブタールを投与した。羽毛除去後,血漿,肝臓,小腸,卵管,深胸筋,そして前脛骨筋と皮膚および残りの部位の8組織の遊離アミノ酸と,組織を加水分解して蛋白態アミノ酸濃度を測定した。各組織における遊離のアミノ酸および蛋白態アミノ酸濃度は組織間で異なっていたが,そのアミノ酸パターンは類似していた。蛋白態アミノ酸に対する遊離アミノ酸濃度の割合は組織により差が認められたが,わずかな例外を除いて組織間で類似していた。

The nutritional value of protein varies between feedstuffs. It is possible to feed animals using crystalline amino acids as a sole nitrogen source, but in practice only some limiting amino acids are added to the diet. In order to use feedstuffs efficiently, it is important to determine exact amino acid requirements. Reported values differ widely because the requirements are affected by various factors. In this report, therefore, the factors affecting amino acid requirements are reviewed as follows: 1) availability of dietary amino acids, conversion factors of nitrogen to protein, interaction of amino acids, and strain, sex and age of animals; 2) amino acid requirements for maximum performance and maintenance, usefulness of nonessential amino acids; 3) plasma amino acid concentration as a parameter to determine amino acid requirements; and 4) nitrogen excretion to reduce environmental pollution. These factors should be considered, it is to improve the dietary efficiency, which is to reduce excess nitrogen excretion for environmental pollution.

Two experiments were conducted to evaluate the effect of amino acid (AA) injections in ovo in Cobb broiler breeder eggs on hatchability and subsequent chick BW. Ln Experiment 1, moisture, crude fat (CF), and CP were analyzed over time during incubation (Day 0, 7, 14, and 19 of incubation). Moisture, CP, and CF of the embryo increased, and moisture, CP, and CF of eggs decreased, as incubation time increased (P < 0.05). Combined egg and embryo AA contents, except Gly and Pro, decreased (P < 0.05) as incubation time increased. However, the pattern of AA in the egg did not change as the embryo developed. In Experiment 2, AA were injected into the yolk or air cell at Day 0 and 7 of incubation. Hatchability was reduced (P < 0.05) when AA were injected at Day 0 of incubation. However, when the AA solution was injected into the yolk sac at Day 7 of incubation, hatchability was not affected, and BW of chicks increased relative to egg weight prior to incubation. These results suggest that in ovo administration of AA may be an effective method of increasing chick BW at hatch.

To determine the amount of endogenous amino acids in budgerigars (sekiseiinko, Melopsittacus undulatus), as the first step of evaluating amino acid requirements, three experiments were conducted. In Experiments 1 and 2, transit time of the feeds through the digestive tract in budgerigars was studied. The birds were given free access to a corn-based diet containing 50% barium sulfate in Experiment 1, and Japanese millets (hie, Echinochloa utilis) with 0.5 ml of 50% barium sulfate solution in Experiment 2. At intervals of 0.5 to 2 hr, roentgenography was conducted to identify the position of the barium sulfate in the digestive tract. The results showed that the transit time of pellets and millets in the digestive tract was within 24 and 27 hr, respectively, in Experiment 3, to determine the amount of endogenous amino acids in budgerigars, the excreta were collected for 24 hr, from 27 to 51 hr after fasting. The excreta were hydrolyzed with 6 N hydrochloric acid at 110 degrees C for 22 hr for the determination of amino acids by HPLC. The endogenous Ala, Arg, Leu, Lys, Phe and Val were estimated to be 34.9, 36.8, 18.5 20.3, 15.3 and 18.9 mu g/day/BW0.75, respectively, which were higher than those in adult roosters.

In a series of experiment to elucidate the rule of amino acid requirements in the fowls from small to large ones, the fractional synthesis rates (FSR) of protein were determined to collect basal data on protein and amino acid metabolism in budgerigars as a small bird. Twenty young adult budgerigars were injected with 0.1 ml/10 g body weight containing 40 mu Ci/100 mu mol phenylalanine/ml in a wing vein, and killed at 2 and 10 min after the injection. The FSR in the whole body, liver, proventriculs and gizzard, intestine and breast muscle were determined. The FSR were not the same in ail tissues, and estimated values were highest in the liver (104.7), and followed by the intestines (68.0), whole body (55.2), proventriculs+Gizzard (46.8), heart (35.8) and breast muscle (26.9%/day).

The alleviatory effect of essential amino acids on growth depression and elevation of plasma methionine (Met) concentration caused by dietary excess Met was studied. Eight-day-old female broiler chicks were divided into 10 groups of 4 chicks with same average body weight and fed each diet containing 0.45 (control) or 1.20% Met diet (excess) for 10 days. To the Met excess diet, 0.4% of individual amino acid, i.e. arginine, glycine (Gly), isoleucine, lysine, threonine (Thr), leucine, valine, or phenylalanine was added. Performance of chicks fed the Met excess diet decreased to 80% of the control group. Lowered performance of chicks fed the Met excess diet was recovered to 90% of the control group by Thr or Gly supplementation to the diet. Plasma concentration of Met increased from 78 to 272 nmol/ml by feeding Met excess diet, but those of Gly, serine and Thr did not change by dietary excess Met. A negative relationship was obtained between plasma Met concentration and body weight gain. The elevated plasma Met concentration was reduced to 63% that of the Met excess diet by Gly and Thr supplementation.

ブロイラーにおいて排泄タウリン量およびタウリン排泄量:含硫アミノ酸(SAA)摂取量比(TS比)を栄養状態の指標とするため,飼料中含硫アミノ酸水準,体重および飼料摂取量のタウリン排泄量に及ぼす影響を,8日齢のヒナを用いて調べた。<br>試験1においてはヒナを単飼ケージにおいて3日間市販飼料を与え,SAA水準0.52,0.82もしくは1.12%飼料に切替えて6日間飼育したとき,タウリン排泄量はSAA不足および至適区では0.5μmol/日で一定であったが,SAA過剰区では飼料切替後2.8μmol/日に増加した。<br>SAA水準0.81%飼料から1.12%飼料に切替後,タウリン排泄量は2日間低く,飼料摂取量の増加に伴い増加し始あ,その後も継続して増加したが,T/S比は2日目まで低く,3日目まで急激に増加し,その後一定となった。<br>SAA過剰飼料を日齢が同じで体重が異なるヒナに自由摂取させたところ,体重が最も低い区でタウリン排泄量が他の区の1.4倍に増加する傾向が見られたが,有意ではなかった。飼料摂取量を自由摂取の2/3に制限したときは,タウリン排泄量は影響を受けなかったが,T/S比は増加した。<br>飼料摂取量を自由摂取の1/3に制限したときは,増体量が減少し,T/S比は40倍に増加した。<br>T/S比は飼料中SAAが不足および至適な区では一定であったが,過剰区では飼料中SAA水準を切り替えて3日目には増加し,10日間以上継続したことから,T/S比は至適な飼料中SAA水準およびSAA摂取量の有効な指標となる可能性が示された。

メチオニン欠乏および過剰によるブロイラーの生産能の低下とそれに対するグリシンの緩和効果の理由を明らかにするため,2つの実験を行った。実験1では,トウモロコシ-大豆粕飼料に段階的にメチオニンを添加してブロイラーの最大生産能の至適なメチオニン水準を求あた。実験2では不足および過剰メチオニン飼料給与時の生産能低下に対するグリシンの緩和効果について調べた。<br>最大成長はメチオニン水準は0.46%,最大成長の70%は0.26および1.56%で得られた。そこで試験2では0.26%, 0.46%と1.56%区を選び,それに0.6%のグリシンを添加した。メチオニン過剰により成長は70%まで低下したが,グリシン添加によって88%まで緩和された。メチオニン欠乏による成長低下はグリシンでは緩和されなかった。体重に差がないにも関わらず,腹腔内脂肪含量はメチオニン過剰では欠乏時に比べ低かった。腹腔内脂肪含量はグリシン添加によって60%までしか回復しなかった。血漿メチオニン濃度はメチオニン過剰飼料によって急激に増加し,グリシン添加によって減少した。血漿グリシン,トレオニンおよびセリン濃度はメチオニン過剰によって低下しなかった。

8から18日齢のブロイラーヒナの最大成長に必要なメチオニン(Met)および総含硫アミノ酸(TSAA)水準推定に際しての,Metとシスチン(Cys)の相互関係について調べるため4つの実験を行った。アーバーエーカー種のブロイラー雌ヒナに,代謝エネルギーは3,200kcal/kgで,TSAAを除く必須アミノ酸のバランスはNRCのパターンに整えた粗蛋白質を17%含む,トウモロコシおよび大豆粕主体の飼料を自由摂取させた。まず,試験1ではMet 0.25%, Cys 0.22%の飼料にL=Metを5段階になるように0-0.8%添加して,増体重および飼料効率を指標として最大生産のためのTSAA水準を求めた。その結果TSAA要求量は0.66%と推定された。次に,試験2ではMetとCysの比がヒナの生産能におよぼす影響について調べた。TSAAが上記水準よりわずかに低い0.60,同水準の0.67およびわずかに過剰0.74%あるとき,さらに試験3ではより過剰な1.30%の4段階でのMetとCysの比をそれぞれ5段階に設定した。最大生産能のためのMet水準は0.3%と推定され,1.30% TSAA飼料では,Metレベルが0.4%以上になるとむしろ生産能は低下する傾向を示し,1.07%に達すると有意にひくくなった。Met水準が至適および過剰に関わらず一定であれば,過剰なCysは生産能に影響しなかった。試験4ではCysの影響を調べるため,Metが0.3%,Cysが0.3%の飼料にCysを0.10-1.00%の4段階になるよう添加してヒナの生産能におよぼす影響について調べた。負の対照区として設けたMet 1.90%飼料では生産能が有意に低下したが,Cys添加区ではCysが過剰でも生産能に負の影響は観察されなかった。<br>以上の結果から,8-18日齢雌ブロイラーヒナの最大生産能にはTSAAが0.66%, Metが0.30%必要であり,そのMetの量はTSAAの量に限らず一定であった。Met含量が0.3%を超えると負の影響が観察されたが,Cysでは1.90%でも過剰の影響は観察されなかった。

加齢に伴うブロイラーの含硫アミノ酸要求量を,増体量と飼料要求率を指標として調べた。<br>実験1では,CP 20.7%,ME 3371kcal/kgの飼料にメチオニンを添加し,含硫アミノ酸(SAA)が等間隔に6段階になる飼料を調製した。その飼料を,4日齢及び24日齢のヒナにそれぞれ20日間給与し,10日目及び20日目に体重と飼料摂取量を記録した。<br>実験2では,CP 18.6%, ME 3175kca1/kgの飼料にメチオニンを添加し,SAA含量が等間隔に6段階になる飼料を調製した。その飼料を,4日齢及び21日齢のヒナにそれぞれ10日間給与し,10日目に体重と飼料摂取量を記録した。<br>実験1の結果,体重はメチオニン添加量の増加に伴って増加し,最大値に達した後減少する傾向を示した。増体量は,4から14日齢では飼料中SAA含量が1.14%の時,最大となった。同様に14から24日齢では1.11%,4から24日齢では1.12%,24から34日齢では1.03%,34から44日齢では0.99%,24から44日齢では1.00%で最大となった。飼料要求率ではメチニオン添加量の増加に伴って減少し,ある時点で最低となった。飼料要求率は,4から14日齢では飼料中SAA含量が1.18%の時,最低となった。同様に14から24日齢では1.08%,4から24日齢では1.10%,24から34日齢では1.05%,34から44日齢では1.02%,24から44日齢では1.03%で最低となった。<br>実験2においても,メチオニン添加量の増加に伴って増体量及び飼料要求率は実験1と同様の傾向を示した。4から14日齢及び21から31日齢では,最大の増体を示す飼料中SAA含量はそれぞれ0.97及び0.89%であり,最低の飼料要求率を示す値はそれぞれ0.97及び0.93%であった。<br>以上の実験の結果,増体量及び飼料要求率から求めた平均SAA要求量は,日齢の増加に伴って減少した。