Amino acid interactions in chick nutrition. 3. Interdependence in amino acid requirements

The quantitative nature of specific interactions between certain indispensable amino acids has been examined in a series of factorial experiments with young chicks.

It was demonstrated that when the dietary concentration of lysine was 1.10 per cent, the arginine requirement of the chick was 0.80 per cent. When the lysine concentration was raised to 1.35, 1.60 or 1.85 per cent of the diet, the arginine requirement was increased to 0.92, 1.04 and 1.15 per cent of the diet respectively. In another experiment, it was found that when due importance had been attached to the interaction between lysine and arginine, the requirements for these amino acids could be lowered to 0.94 per cent and 0.81 per cent respectively. These concentrations are considerably lower than those normally recommended for young chicks.

The interrelationship between leucine and isoleucine has also been defined in quantitative terms. At concentrations of 1.40, 2.15 or 2.90 per cent leucine, the isoleucine requirement was 0.58, 0.62 and 0.65 per cent of the diet respectively.

In a further study, a similar dependence of valine requirements upon the dietary concentration of leucine was observed: at concentrations of 1.40, 2.40 or 3.40 per cent leucine, the valine requirement was shown to be 0.77, 0.89 and 1.01 per cent respectively. The results of the experiment on the threonine‐tryptophan interaction indicated that at concentrations of 0.80, 1.30, 1.80 or 2.30 per cent threonine, the tryptophan requirement was 0.17, 0.18, 0.19 and 0.20 per cent of the diet respectively.

The results of the present study permit the general conclusion that the requirements of amino acids are interdependent.     

Lysine requirement of broiler chicks as affected by protein source and method of statistical evaluation 1

1. An experiment was designed to test if the lysine requirement, expressed as g lysine/kg CP, was the same for several protein sources.

2. Groundnut meal, groundnut meal adjusted with indispensable amino acids or sesame meal supplied the dietary CP at 180 g/kg diet. Increments of lysine (1.5 g/kg diet) were added to each of these diets.

3. The gain, food intake and food efficiency responses of broiler chicks were analysed using a quadratic equation and a two‐slope method. An estimate of lysine requirements was also obtained from a survey of college students.

4. The different methods produced widely different estimates of lysine requirement.

5. The average lysine requirement was estimated at 50.1 g lysine/kg CP for groundnut meal, 61.7 for adjusted groundnut meal and 54.9 for sesame meal.

6. Reasons for the effect of statistical analysis and protein source on lysine requirement are discussed.     

Food intake adjustments of chicks: Short term reactions to deficiencies in lysine,methionine and tryptophan

1. Two experiments were conducted to compare food intake responses of broiler chicks fed diets varying in lysine, methionine, and tryptophan. Diet D was formulated to create simultaneous deficiencies of lysine, methionine, and tryptophan. Diet A matched National Research Council (1984) recommendations for broilers, and diets B and C were, respectively, 2:1 and 1:2 mixes of diets A and D.

2. Short‐term food intake can provide information on the sequences of adaptation of chicks to a diet deficient in essential amino acids.

3. Chicks consumed 26% less of diet D than A during the first 24 h posthatch. When chicks fed diet A or D to 7 d of age were then fed one of 4 diets singly, within 24 h intake was lowest for chicks fed diet D. Within 48 h, food intake of diet C was more than that of diet D and less than that of diet A, while for diet B intake was more than of diet D but not different from diet A.

4. In the second experiment, chicks were fed diet A to 8 d and then diets A or D alone or given a choice of diets A and D from 8 to 20 d of age. Within 4 to 8 h, food intake of chicks fed diet D alone decreased markedly followed by partial recovery within 24 h. In a choice setting, consistent preference of Diet A over Diet D was observed within 7 h followed by stabilisation at about 65% diet A to 35% diet D.

5. Chicks fed diet D alone from 8 to 20 d of age, then placed in the same choice situation preferred diet A to D with a delay of less than one h and stabilisation at about 85%. Chicks provided a choice of diets A and D from 8 to 20 d, and then diet D alone reduced their food intake more quickly than those not given a choice initially.

6. Broiler chicks appear to react to amino acid deficiencies within a short period (hours) by adjusting their feed intake and/or selection. The response is influenced by age and prior experience.     

Effects of dietary supplements on the nutritive value of jack beans (canavalia ensiformis) for the young chick

1. Two experiments were conducted with young chicks to examine the efficacy of dietary supplements of amino acids, creatine and potassium acetate in the alleviation of adverse effects of auto‐claved jack beans (AJB).

2. Creatine supplementation of AJB diets markedly enhanced the efficiencies of food and nitrogen utilisation of chicks, restoring these indices to control values. The improvement in nitrogen utilisation was enhanced further on providing creatine with a mixture of 2‐aminoiso‐butyric acid, arginine and lysine.

3. Potassium acetate induced striking improvements in the nitrogen retention efficiencies of chicks fed on AJB diets.

4. Liver weights, as a proportion of body weight, generally increased on feeding AJB diets, the effects being marked with the AJB diet supplemented with arginine and lysine.

5. Hepatic urea concentrations were elevated in all groups receiving AJB. Canavanine, a toxic amino acid component of AJB, could not be detected in acid hydrolysates of livers from chicks fed this legume.

6. Temperature and the volumes of water employed in the preparation of AJB are important determinants of its nutritional value.     

Effects of group size on the feeding behaviour and growth of chicks

1. The aim of the study was to see if social facilitation of feeding has a lasting effect on the growth of chicks.

2. In two experiments, newly hatched hybrid and Brown Leghorn chicks were reared in isolation and in small groups of different sizes, and their growth, food intake and feeding activity were measured for several eeks.

3. Initially, chicks of both strains grew faster when they were grouped than when they were in isolation, as a result of a more efficient conversion of food rather than as a result of increased consumption.

4. Later, chicks in the largest groups converted their food less efficiently, possibly because of increased disturbance.

5. From 6 to 12 weeks, when the chicks were in larger cages, growth rate was not affected by group size, but food intake and food conversion were affected differently in the two strains.

6. In general, the isolated chicks ate about the same amount as the grouped ones, and it is doubtful whether social facilitation of feeding occurred at all in these experiments.     

Changes in free amino acid concentrations in the blood,brain and muscle of heat-exposed chicks

1. An experiment was conducted to analyse the changes in free amino acid concentrations in the blood, brain and muscle of chicks in response to 15 or 30 min exposure to high ambient temperature (HT).

2. Food intake and body weight were not affected, while rectal temperature was significantly increased by short-term HT exposure.

3. Several free amino acid concentrations increased in the blood, brain and muscle even with short-term HT, whereas levels of a few amino acids declined significantly. As well as the nonessential amino acids, essential amino acids also significantly increased with exposure to HT.

4. 3-Methylhistidine, a marker of proteolysis, significantly declined in the muscle of HT chicks, implying a reduction of protein breakdown under HT.

5. These results indicate that alteration of protein metabolism may occur in chicks even with short-term heat exposure.     

Effects of high inclusion rates of salseed meal in the diet of chicks

1. Starter diets containing either maize or salseed meal to replace the maize were fed to chicks over a period of 2 weeks.

2. Growth rate, food intake, food utilisation and proportion of dietary nitrogen retained were much poorer in chicks receiving salseed meal.

3. The chicks receiving salseed meal developed pathological lesions in liver and kidney.

4. The red blood cell count, white blood cell count, haemoglobin concentration and packed cell volume of the chicks receiving salseed meal were lower than those of chicks receiving maize.

5. The apparent metabolisable energy value of salseed meal was determined as 6.83 MJ/kg.     

Food intake adjustments of chicks: Short term reactions of genetic stocks to deficiencies in lysine,methionine or tryptophan

1. Growth, food intake, and food preference were measured in two experimental lines (White Rocks and White Leghorns) of chickens fed diets varying in content of lysine, methionine, or tryptophan. Diet A was balanced in all amino acids, while the remaining 6 diets were moderately ( ～ 30%) or slightly ( ～ 15%) deficient in either lysine, methionine, or tryptophan relative to NRC recommendations for broiler diets.

2. Body weight and food utilisation efficiency of White Leghorns at 10 d of age were not affected by diet, whereas the lower concentrations of lysine and methionine depressed these traits in White Rocks.

3. Tryptophan deficiency reduced food intake of White Leghorns, but not White Rocks.

4. With choice feeding of balanced and deficient diets from day 10 to 16, preferences between the diets were minimal for White Leghorns, whereas for White Rocks there was an almost immediate preference for the balanced diet, followed by lack of preference or preference for the deficient diet.

5. Apparently for some genetic stocks there is rapid adjustment to deficiencies in these amino acids with overconsumption, followed by compensation for preference of the balanced diet. The response, however, will vary depending on the deficient amino acid.     

Voluntary food intake variation in chickens on lysine-free diet is attributed to the plasma lysine concentration

1. Growing chickens decrease their voluntary food intake when they receive a diet deficient in a single essential amino acid. Our previous studies suggest that the decreased food intake was associated with some metabolic changes.

2. In order to reveal the involvement of plasma lysine fluctuations in the reduction of food intake, we examined whether maintaining the plasma lysine concentration in chickens on a lysine-free diet (the purified diet contained no lysine) restored the food intake to that of the control (lysine hydrochloride 11.9 g/kg) group.

3. Male egg-type chickens at 21 d of age were injected with lysine at doses of 0.1 g/ml one hour after presenting the lysine-free diet. This injection increased the plasma lysine concentration one hour later and kept it similar to that of the control group for the following 2 h. Chickens ate the lysine-free diet as much as the control diet when their plasma lysine concentration was kept at a similar level to the control group. Injection of saline or alanine (0.12 g, isonitrogenous to lysine 0.1 g) into the crop of chickens on the lysine-free diet did not bring about the variations of food intake and plasma lysine concentrations as observed in those with lysine.

4. These findings show that the food intake variation was attributed to the plasma lysine concentration in the chickens on the lysine-free diet.     

Individual variation in the content of free amino acids observed in the blood and muscle of chicks fed a single meal daily

1. Fifty broiler chicks in individual cages, were fed on a balanced diet ad libitum until 10 d old and then given a single meal daily. Blood and pectoral muscle samples were taken from each. Free aspartic acid, threonine, serine, glutamic acid, glycine, alanine, valine, cystine, isoleucine, leucine, phenylalanine, lysine and arginine were determined.

2. Free amino acid concentrations varied greatly between birds. Values for the coefficient of variation ranged from 0.21 for serine in both tissues to 0.571 and 0.749 for valine and lysine in blood and muscle respectively.

3. Many correlations for pairs of amino acids did not seem related to the body weight of chicks.     

Influence of ascorbic acid on the adverse effect of feeding a diet containing excess tyrosine to chicks

1. The effects of dietary or parenteral administration of ascorbic acid on the adverse effects of excess dietary tyrosine were investigated with young male White Leghorn chicks in a 2‐week experiment.

2. Addition of 10 g ascorbic acid/kg to the control diet (without excess tyrosine) produced no beneficial effects on performance. Excess dietary tyrosine caused depressions in all measures of performance.

3. Adding 0.1, 1, 10 or 20 g ascorbic acid/kg to the diet containing excess tyrosine tended to improve performance.

4. Subcutaneous injection of 50 mg ascorbic acid/bird d to chicks receiving excess tyrosine brought about a significant improvement in body‐weight gain.

5. The elevation of plasma free tyrosine caused by excess dietary tyrosine decreased as dietary ascorbic acid increased.

6. Ascorbic acid can alleviate, though not completely counteract, the adverse effect of excess dietary tyrosine.     

Effects of amino acid balance and energy: Protein ratio on energy and nitrogen metabolism in male broiler chickens

1. An experiment was performed with growing broiler chickens (14 to 21 d old) to examine 3 diet characteristics which have been implicated in regulatory elevation of metabolic rate: an unbalanced amino acid mixture, high dietary energy concentration and low protein concentration.

2. Differences in energy expenditure could be explained almost entirely (93%) by differences in quantities, and therefore costs, of protein and fat accretion. There was no indication of regulatory diet‐induced thermogenesis. Heat production was not significandy correlated with CP:TME ratio and was negatively correlated (P<0.01) with dietary TME concentration.

3. Heat production was closely correlated (P< 0.001) with rate of protein accretion, which in turn was more strongly associated with intake of the first‐limiting amino acid (lysine) than with total protein intake. Heat production on an imbalanced, lysine‐limited, amino acid mixture was no greater than on a balanced amino acid source with the same lysine concentration.

4. There was no indication of a stimulation of heat production by excess amino acids. Heat production, adjusted for body weight by covariance analysis, was similar on paired diets which had identical lysine concentrations but a 1.5‐ or 2‐fold difference in crude protein concentration.

5. There was a strong negative correlation (P< 0.001) between protein retention per g of lysine consumed and lysine :CP ratio, suggesting that, in this case, response to a limiting amino acid was improved by the presence of a super‐abundance of other amino acids.     

Dietary lysine concentrations from deficient to excessive and the effects on broiler chicks

1. An experiment was designed to test the response of broiler chicks (0–21 d) to dietary lysine concentration. Concentrations ranged from 9.9 to 14.4 g of lysine per kg diet when energy was 13.4 MJ ME/kg.

2. Estimates of the concentration of lysine needed for maximum body weights gain, food consumption and gain:food ratio were calculated using two statistical methods. An average of these estimates was 12.0 g lysine/kg diet to 21 d of age.

3. Chicks given 13.9 or 14.4 g lysine/kg diet were negatively affected by these concentrations. The decreases in average weight gain, food consumption and food efficiency were caused mainly by several chicks that developed severe leg problems and were much smaller than their pen mates. Chicks with no leg problems gained weight as rapidly as chicks receiving optimal amounts of lysine.     

The effect of sodium sulphate and methionine on the utilisation of non‐protein nitrogen by laying hens

1. The response of layers to adding diammonium citrate (DAC), sodium sulphate or methionine to a basal diet containing 136–3 g protein/kg was determined.

2. Supplementing the diet with DAC equivalent to 25 g protein/kg did not improve egg production, the efficiency of food utilisation, egg weight, nitrogen retention or the apparent absorption of lysine and methionine; increases in food intake and in the concentration of methionine in the serum and liver were observed.

3. Adding sodium sulphate, alone or with DAC, did not affect the variables noted above.

4. Supplementation of the basal diet with methionine increased egg production, egg weight, food intake and the concentrations of lysine in the serum and liver.

5. It is concluded that the supplemental NPN was used only in serum protein synthesis.     

Effect of dietary energy concentration on the response of laying hens to amino acids

1. A hypothesis, that the optimum amino acid concentration in the diet is not directly proportional to the dietary energy concentration, but changes in inverse proportion to the change in food intake resulting from a change in energy concentration, was tested in three experiments.

2. Response experiments involving the amino acids methionine, lysine and isoleucine were conducted, in each case at three dietary energy concentrations, using a diet dilution and blending technique, thereby ensuring a constant ratio between background amino acids and the first‐limiting amino acid in all diets, and also keeping the ratio of amino acids to energy constant as energy varied.

3. A common response curve relating egg output (g/bird d) to amino acid intake (mg/bird d) for each amino acid, fitted by means of the Reading Model, adequately described the response at each of the dietary energy contents. This implies that energy does not influence egg output directly, but only indirectly through its effect on food intake and hence on amino acid intake.

4. Both amino acid and energy concentration significantly influenced food intake. Energy intake was not constant over all dietary energy concentrations, being lower at low energy levels and higher at high energy concentrations.

5. It is concluded that amino acid requirements should not be stated either as percentages or as ratios with energy. Optimum amino acid intakes and energy concentrations should be calculated; the expected food intake should then be predicted, after which the appropriate concentration of nutrients in the diet can be determined.     

Physiological responses to central and peripheral injection of polyinosinic-polycytidylic acid in chicks

1. The purpose of the present study was to determine if intracerebroventricular (ICV) and intraperitoneal (IP) injection of polyinosinic-polycytidylic acid (poly I:C), a viral mimetic that binds to toll-like receptor-3 (TLR3), affects food intake, voluntary activity, cloacal temperature, plasma corticosterone (CORT) and glucose concentrations, and crop emptying rate in chicks (Gallus gallus).

2. Both ICV and IP injection of poly I:C significantly decreased food intake.

3. IP but not ICV injection of poly I:C significantly suppressed voluntary activity, whereas ICV injection decreased time spent sitting. Both ICV and IP injection of poly I:C significantly increased plasma CORT and glucose concentration. Neither ICV nor IP injection of poly I:C significantly affected cloacal temperature.

4. In addition, ICV injection of poly I:C significantly reduced crop emptying rate, whereas IP injection had no effect.

5. These results suggested that central TLR3 is related to anorexia, stress response and retardation of crop emptying while peripheral TLR3 is related to anorexia, change in behaviour and stress responses during viral infection in chicks.     

Possible role of central interleukins on the anorexigenic effect of lipopolysaccharide in chicks

1. The purpose of the present study was to determine if central interleukin-1β (IL1β), interleukin-6 (IL6) and interleukin-8 (IL8) affect feeding behaviour in chicks (Gallus gallus) and examine if central interleukins are related to the lipopolysaccharide (LPS)-induced anorexia.

2. Intra-abdominal (IA) injection of LPS significantly suppressed feeding behaviour and significantly increased mRNA expression of IL1β and IL8 in the diencephalon when compared to the control group, while IL6 tended to be increased.

3. Intracerebroventricular (ICV) injection of 200 ng IL1β significantly decreased food intake at 60 min after the injection while IL6 and IL8 had no effect.

4. IA injection of these ILs (200 ng) had no effect on food intake in chicks.

5. ICV injection of 200 ng IL1β did not affect water intake and plasma corticosterone concentration, suggesting that central IL1β might not be related to the regulation of drinking behaviour and the hypothalamus–pituitary–adrenal axis.

6. The present study demonstrated that central IL1β but not IL6 and IL8 might be related to the inhibition of feeding in chicks.     

Effects of faba bean tannins on the growth and histological structure of the intestinal tract and liver of chicks and rats

1. Diets containing a freeze‐dried tannin extract from faba beans (Vicia faba L.) at concentrations of 0, 8 and 16 g/kg were fed to growing chicks and rats.

2. Chicks fed on the tannin‐containing diets exhibited a high mortality and significant decreases in body‐weight as well as lower food intakes and higher food intake:weight gain ratios (P<0.01). In rats there was no mortality but the growth and food intake were adversely affected (P< 0.05).

3. Histological changes occurred in the ileal mucosa of chicks. Atrophy and shortening of villi with distortion of their architecture were observed. Similar histological disorders but less pronounced were also found in rats.

4. Histopathology of the liver of both chicks and rats showed an hydropic degeneration of hepatocytes, clearly more severe in the former than in the latter.     

Feeding and pecking behaviour in ostrich (Struthio camelus) chicks in captivity

1. Three sets of experiments were performed on two batches of ostrich chicks to investigate the factors affecting the pecking and feeding behaviour of grouped individuals.

2. Chicks showed no significant alteration of their feeding behaviour in response to raising pen walls in the rearing facility from 30 to 60 cm.

3. Further analysis on a different set of birds revealed consistent short term individual differences in the frequency of feeding and non‐feeding pecks.

4. There were significant pen effects on behaviour suggesting the possible development of a pen ‘culture’ of pecking behaviour.

5. Pecking behaviours in 26 to 33 d‐old chicks, with the exception of drinking, were generally negatively correlated, so any non‐food pecking by a chick was generally associated with fewer pecks targeted at food.

6. By the age of two months chicks were pecking at food on the floor to a far greater extent than at any food presented in food trays.     

Supplementation of groundnut‐based broiler chick diets with pyridoxine

1. Broiler chicks fed on a semi‐purified diet containing 230 g crude protein and less than 5 mg pyridoxine/kg had poor growth rates and high mortality.

2. When a milled, unsupplemented diet based on rice and groundnut was fed, food utilisation, carcass fat content and serum aspartate amino transferase [EG 2.6.1.1] activity indicated the need for supplementation with at least 3 mg pyridoxine, or a total concentration of 8.8 mg/kg diet.

3. With a maize‐groundnut diet body‐weight gain, food intake and tissue aspartate aminotransferase activities suggested that dietary supplementation with pyridoxine was unnecessary, but food utilisation indicated a need for supplementation with 3 mg or a total intake of 9 mg pyridoxine/ kg diet.

4. A practical broiler chick starter diet was used to show that the total concentration of pyridoxine should be at least 7.2 mg/kg when maize‐groundnut diets are fed.