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In order to synthesize human erythropoietin protein in the oviduct of laying hens, localized in vivo gene transfer was attempted by using electroporation. In Experiment 1, transcriptional activities were compared by using four viral and cellular promoters, i.e., the 1.35-kbp long ovalbumin promoter, SV40 early promoter, Rous sarcoma virus long terminal repeat (RSV LTR), and the miw promoter, which is a hybrid of RSV LTR and chicken beta-actin promoter. These promoters were fused immediately upstream to the chloramphenicol acetyltransferase reporter gene. The results of chloramphenicol acetyltransferase activity showed that the miw promoter was the strongest, followed by SV40, RSV LTR, and the ovalbumin promoter in decreasing order. The intensity of the miw promoter was 250 times as high as that of the ovalbumin promoter. In Experiment 2, plasmid DNA containing the human erythropoietin gene, driven either by the ovalbumin promoter or the miw promoter, was transfected in vivo, and the production of human erythropoietin protein was detected by ELISA. The results indicated that the synthesis of human erythropoietin protein was attained in the chicken oviduct, and its concentration was higher when driven by the miw promoter than the ovalbumin promoter.

The effect of administration of clenbuterol, a beta-adrenergic agonist, on live weight gain and protein synthesis of liver and breast muscle was investigated in 32 White Leghorn chicks. Protein synthesis was measured by injection of [3H]phenylalanine in a wing vein using the flooding dose method. No significant changes in body weight gain were caused by dietary administration of the beta-agonist at .25 mg/kg of diet from 3 to 6 wk of age, but fat retention in the liver and breast muscle was significantly reduced by the drug treatment. No stimulating effect on protein synthesis of the beta-agonist administration was found either in the breast muscle or in the liver. Protein synthesis in the breast muscle was unchanged whereas that in the liver was reduced significantly by feeding clenbuterol.

Influence of aging on N and ME utilization in germ-free and conventional (CV) chicks was investigated at Stage 1 (2 to 6 days old) and Stage 2 (10 to 14 days old). Chicks were fed diets for ad libitum consumption with protein concentrations of 116, 220, or 445 g/kg diet. The N utilization was not affected by the gut microflora at either stages, but it significantly decreased for chicks on the high-protein diet compared with those on the low-protein and adequate-protein diets. The ME values of diets were not influenced by treatments, except for the high-protein diet at Stage 1, in which ME was significantly reduced.

Male and female broilers were given diets (6 males and 6 females per diet) containing varying percentages of sorbose (0, 3, 6, and 9%) and fed for ad libitum access from 28 to 56 days of age. Body weight gain and feed intake were decreased with increasing dietary sorbose, particularly in male birds fed diets containing 9% sorbose, although feed efficiency and N retention rate were not influenced by dietary treatments. Absolute and relative abdominal fat weights were higher in females than in males and decreased with the increasing levels of dietary sorbose in both sexes. Fat content in the pectoral muscle also decreased as dietary sorbose increased. Dietary sorbose did not have significant effects on serum glucose, triglyceride, total cholesterol, low density lipoprotein, very low density lipoprotein, and chylomicron levels in either male or female birds. The ME values of diets decreased as dietary sorbose increased. Palmitic acid content of abdominal fat was significantly lower in birds fed the 9% sorbose diet than in birds fed the control diet. The reverse was true for linoleic acid content. It was concluded that dietary sorbose can be used as a potential regulator of lipid deposition in broilers.

Single Comb White Leghorn laying hens received ad libitum diets (10 birds per diet) containing varying concentrations of sorbose (0, 100, and 200 g/kg diet) for 4 wk. Body weight gain and feed intake decreased with increasing dietary sorbose. Serum triglyceride, cholesterol, low density lipoprotein, very low density lipoprotein, and chylomicron levels were significantly reduced, in dose-dependent fashions, as dietary sorbose increased, whereas serum glucose level remained unchanged by the dietary regimens. Absolute and relative weights of abdominal fat were also decreased by increasing dietary sorbose. Liver color improved; it became less white and less yellow with the supplement of dietary sorbose. Hen-day egg production rate was not affected with dietary sorbose, and hence, it has been shown that dietary sorbose can be used as a potential regulator of lipid metabolism in the laying hen.

Age dependency of triiodothyronine (T3)-induced thermogenesis of young chicks at 1 and 2 wk of age was investigated by dietary administration of .5% propylthiouracil (PTU), an inhibitor of thyroid hormone synthesis. Heat production measured by indirect calorimetry was increased by an intraperitoneal injection of T3, but the thermogenic effect was larger at 2 wk than at 1 wk of age. Heat production at 2 wk of age was decreased by PTU when the T3 was not administered, whereas the inhibitory effect of PTU was not found at 1 wk of age. It would appear, therefore, that little or no thermogenesis is responsive to exogenous T3 in young chicks at 1 wk of age even though the suppression of endogenous T3 is likely to occur by the PTU treatment.

The effects of alanine-producing bacteria administered orally on the growth of chicks was investigated. The chicks were given diets containing adequate amounts of only the essential amino acids as sources of nitrogen: a basal diet (BD); a BD plus 40 g of urea per kilogram of diet (UD); a UD with bacteria named AR-8-3; a UD with bacteria named AB-605; and a BD plus 59.4 g and plus 118.7 g of L-alanine per kg of diet, respectively, from Day 8 to Day 15. The growth of chicks fed diets containing urea or alanine was significantly faster than that of the BD controls; no significant difference in growth was detected among the groups given the UD and bacteria. Since viable bacteria could not be detected from the intestinal content or from excreta for both groups given the bacteria, the establishment and achievement of alanine-producing activity by the bacteria in the gastrointestinal tract were considered doubtful. The supplement with 59.4 g of alanine per kg of diet improved the growth rate, but the higher inclusion (118.7 g of alanine per kg of diet) resulted in no further improvement.

An experiment was conducted to evaluate the relative biopotency of triiodothyronine (T3) and of thyroxine (T4) for inducing oxygen consumption in young chicks. Male chicks, Single Comb White Leghorn, at 40 days of age were distributed into five experimental groups, one control group of 6 birds and four hormone-treated groups of 3 chicks. The chicks were injected intraperitoneally with T3 or T4 at a dose of 500 or 1,000 micrograms per kg of body weight. Thereafter, oxygen consumption was measured by indirect calorimetry using a respiration test apparatus. Oxygen consumption was significantly increased at 2 and 4 h for the birds treated with T3 or T4 compared with the control birds, except for the chicks treated with T4 at 500 micrograms at 2 h. From the coefficients for a multiple regression equation of oxygen consumption on T3 and T4, the data showed that T3 was 2 to 3 times as biologically active as T4.

The present study using 8-day-old White Leghorn male chicks, was made to determine whether retarded growth of chicks fed a tyrosine excess (Tx) diet ad lib was due to the depression in feed intake or the reduced efficiency of feed utilization. A Tx diet was prepared by supplementing a 20% crude protein basal diet with 5% L-tyrosine. The levels of feed intake prepared for 10 days were as follows: 160 (corresponding to the amounts of the basal diet the chick would consume ad lib), 140, 120 (corresponding to the amounts of the Tx diet the chick would consume ad lib), 100, and 80 g per bird. Body weight gain, gain:feed ratio, and energy retention rate of chicks fed the basal or Tx diet decreased proportionally as the level of feed intake was decreased. The addition of Tx to the basal diet significantly reduced the body weight gain, gain:feed ratio, metabolizable energy (ME) value, and nitrogen and energy retention rates at all levels of feed intake. Body composition was not significantly affected by the addition of Tx to the basal diet at all levels of feed intake. The plasma free tyrosine concentration was markedly increased by the addition of Tx to the basal diet and also with increments in feed intake. Dietary Tx per se had a decreasing effect on body weight gain, efficiencies of dietary nitrogen, energy utilization, and ME value. The growth retardation of chicks fed a Tx diet ad lib was due to the combined effects of the depression in feed intake and the reduced efficiency of feed utilization.

A study on chickens was conducted to investigate whether or not: a) excess dietary tyrosine increases the content of tyrosine metabolites in plasma and excreta, b) these elevations of tyrosine metabolites are presented by increasing dietary protein level or supplementing with ascorbic acid (AA), and c) urine is a major excretory route of tyrosine metabolites. Chicks fed a 10% protein diet with excess tyrosine developed external foot lesions accompanied by retarded growth and depressed feed intake. These adverse effects were alleviated by elevating dietary protein level or supplementing with AA. Excreta and plasma of chicks fed the 10% protein diet contained small or undetectable amounts of free tyrosine, 4-hydroxyphenylpyruvate (4-HPP), 4-hydroxyphenylacetate (4-HPL), and 4-hydroxyphenylacetate (4-HPA), while these metabolites were markedly increased by the addition of excess tyrosine to the 10% protein diet. From the results with colostomized cocks, the major source of 4-HPP, 4-HPL, and 4-HPA excreted by chicks fed a tyrosine excess diet was considered more likely to be of urinary than fecal origin. Elevated contents of tyrosine and its metabolites in plasma were partially counteracted by increasing dietary protein level or AA supplementation. In excreta, elevated contents of tyrosine and its metabolites caused by excess tyrosine were reduced by increasing dietary protein level and supplementing with AA when expressed in the proportion of tyrosine intake. These results suggest that the beneficial effects of increased dietary protein level and supplementation with AA are related to enhanced ability of chicks to degrade excessively ingested tyrosine.

Chicks were given diets containing varying amounts of dietary acetic acid (0, 12.7, 25.4, 38.1, 50.8, and 63.5 g/kg diet) under ad libitum feeding in Experiment 1 and under equalized feeding (average feed intake of Experiment 1) conditions in Experiment 2. In Experiment 1, values for body weight gain (g/10 days), feed intake (g/10 days), fat retention (g/10 days), and energy retention (kJ/10 days) were linearly lower as dietary acetic acid was increased. In Experiment 2, values for body weight gain, protein retention, and fat retention (grams/10 days), and for energy retention (kiloJoules/10 days) were changed curvilinearly. These values tended to increase until diets contained 25.4 g acetic acid/kg diet and then decreased significantly when diets contained 50.8 g acetic acid/kg diet. All chicks given the 63.5-g acetic acid/kg diet died during Experiment 2. Dietary acetic acid had a detrimental rather than a beneficial effect on chick performance, particularly at the high level.

To demonstrate the nutritional specificity of essential amino acids, body weight change and nitrogen balance were compared in chicks equalized-fed a histidine-free or lysine-free diet with 0, 20, 40, 60, 80, or 100% requirement of sulfur-containing amino acids (SAA). With an increase of SAA level up to 40% of its requirement, body weight and nitrogen balance increased irrespective of complete deficiency of histidine or lysine. Above 40% of the SAA requirement, these parameters reached plateaus. The intersection points of the two regression lines at which the responses of body weight change and nitrogen balance altered were 49.8 and 52.1% in the chicks fed the histidine-free diet and 44.7 and 32.6% in the chicks fed the lysine-free diet, respectively. These values are quite agreeable with the estimate of the nutritional score of the amino acid mixtures in an earlier report (Kino and Okumura, 1986). It was demonstrated that the effect of essential amino acid deficiency does not always directly associate with the percentage deficit relative to its requirement, and there exists nutritional specificity of essential amino acids.

Whole-body protein turnover rates were measured in chicks fed control, histidine-free (-His), and methionine plus cystine-free (-Met, Cys) diets. After chicks were fed the experimental diets ad libitum for 7 days, they were injected with a massive dose of L-[4-3H]-phenylalanine (40 microCi/100 g body weight) and rate of protein synthesis was estimated from the incorporation of phenylalanine into protein. The rate of protein degradation was estimated as the difference between the synthesis and growth rates of protein. In chicks fed the amino acid-devoid diets, the fractional synthesis rates of protein (FSR, percent per day) were significantly lower than those in control chicks, whereas fractional degradation rates of protein (percent per day) were constant for all dietary treatments. The FSR in -Met, Cys chicks was lower than that in -His chicks and the lower FSR in -Met, Cys chicks seemed to result in more body protein loss. The RNA/protein ratio of chicks was almost the same in all treatments, but the protein synthesized per unit RNA varied depending on the dietary treatments. The lower amount of protein synthesized per unit RNA in -Met, Cys chicks was postulated to result from inhibition of protein synthesis by a shortage of available methionine associated with a higher degradation rate of methionine itself. These results indicated that different growth responses between -His and -Met, Cys chicks were primarily caused by the difference in the rates of protein synthesis.

Diets completely devoid of single essential amino acids were fed to chicks from Day 14 to Day 24 after hatching to investigate the effect on chick growth and nitrogen and energy balances under ad libitum- and equalized-feeding conditions. The effects were different depending upon the amino acid omitted from the diet and were significantly associated with voluntary food intake. Among the essential amino acids, lysine and histidine had the least effect and methionine plus cystine had the severest effect. With equalized-food intake, body weight loss and the reduction in nitrogen balance were diminished by about 44 and 29%, respectively, and the differences in energy utilization disappeared. The possible factors that may explain the nutritional specificity of amino acids are discussed.

This study was conducted to clarify the effect of the gut microflora on the utilization of dietary diammonium citrate in the chick. Germ-free and conventional Single Comb White Leghorn chicks were given a basal diet, which contained adequate amounts of all essential amino acids but none of the nonessential amino acids as nitrogen sources, or a diammonium citrate-supplemented diet. Irrespective of presence or absence of the gut microflora, values for body weight gain, feed efficiency, and protein and energy utilization were improved by supplementing the basal diet with diammonium citrate. This suggests that the gut microflora are not required for the chick to utilize diammonium citrate.