Reticulocytosis in response to dietary antioxidants.

Alpha-tocopheryl acetate, 1, 2, dihydro-6-ethoxy-2, 2, 4-trimethylquinoline, and butylated hydroxytoluene increased the number of circulating reticulocytes when added to the diet of chickens. Hematocrit values were not reduced and erythrocyte life-spans were not shortened by the antioxidants. The reticulocytosis is attributed to delayed loss of reticular material from the maturing erythrocytes. components.

Sodium chloride supplementation of all plant protein broiler diets.

Male broiler chicks were fed all plant protein diets with soybean meal or a mixture of soybean and canola meals as the source of supplementary protein from 0 to 4 weeks of age. Supplementation of the diets with .25% sodium chloride did not meet the requirements of the chicks for maximum growth. Growth was accelerated when the dietary sodium chloride concentration was increased to .50 and 1.00%.

Plasma triglyceride and glucose clearance in broiler-type and white Leghorn chickens with different degrees of adiposity.

Broiler-type and White Leghorn chicks were given diets containing 30.5, 26.2, or 22.3% protein with and without addition of 5% corn oil during an 8- to 9-week conditioning period. The absolute weight of the abdominal fat pad was greater in the broiler-type birds on all dietary treatments. As a percentage of body weight the abdominal fat pads were similar in broiler-type and White Leghorn birds only when the diet contained 30.5% of protein without added oil. Following a 16-hr fast, plasma glucose was higher in the broiler-type than in the White Leghorn birds, whereas plasma triglyceride concentrations were higher in White Leghorns. In birds refed a high-fat meal, plasma glucose showed little change except in the broiler chickens previously fed the 30.5% protein diet without added oil. In these birds plasma glucose declined over a 5-hr period to reach a mean value of 130 mg/100 ml. Plasma triglyceride concentrations in both breeds were markedly elevated within 45 min of refeeding with a high-fat meal, but the peak concentrations were higher in the White Leghorns than in the broiler-type birds. Previous consumption of the high-oil diet increased postprandial triglyceride concentration in the plasma of the broiler-type but reduced it in the White Leghorn chickens. The difference in response of the chickens of the different genetic stocks is attributed to differences in the development of the activities of the systems associated with 1) fatty acid absorption and movement of triglycerides from the intestinal mucosa to the circulation and 2) clearance of plasma triglycerides to the adipocytes as a result of lipoprotein lipase activity.

Plasma corticosterone concentrations in growing chickens fed diets formulated to promote different rates of growth.

No significant differences in plasma corticosterone concentrations were noted among chicks fed diets containing 16 to 25% protein or diets containing 2,800, 3,200, or 3,600 kcal metabolizable energy per kg to 6 wk of age. The ingredients used in diet formulation did, however, affect plasma corticosterone. Higher plasma corticosterone was associated with 2,800-kcal diets containing high concentrations of cornstarch and no cereal grains compared with 2,800-kcal diets containing low concentrations of cornstarch and cereal grains. In a second experiment, chicks were fed diets containing different concentrations of lysine and methionine from hatching to 4 wk of age. Half the chicks on each dietary treatment were conditioned to handling by daily gentling. Plasma corticosterone concentrations were reduced in the conditioned chicks. Plasma corticosterone increased during a period of up to 15 min after catching when the chicks were kept in a box prior to drawing blood samples. Excess dietary lysine significantly reduced plasma corticosterone in the gentled chicks but not in the control chicks.

Effects of energy source and feed access on abdominal adipose tissue in chickens of two broiler strains.

Broiler-type pullets of two commercial strains (H & N and Hubbard) were fed either a high fat or high carbohydrate diet from 0 to 20 wk of age. Feeding was ad libitum or restricted to 3 (high-fat) or 3.3 (high-carbohydrate) h/day. Adipocyte characteristics of abdominal fat pads were determined at 5, 8, 11, 17, and 20 wk of age. Birds fed the high carbohydrate diet ad libitum had greater feed and energy intake with no reduction in the efficiency of energy utilization than birds fed the high fat diet ad libitum. The greater energy intake did not increase abdominal fat pad weight. Restricted feeding of the high fat diet produced comparable weight gains, up to 17 wk of age, to those of birds fed ad libitum but at lower energy cost. Adipocyte numbers and mean size were similar for the two strains and responded similarly to the dietary treatments. A characteristic bimodal distribution of cell size, consisting of a primary population of large adipocytes and a secondary population of small adipocytes, was apparent in 5-wk-old birds fed ad libitum. The secondary population of adipocytes in the feed-restricted birds appeared by 8 to 11 wk of age. Lipoprotein lipase activity in the adipose tissue was determined at 20 wk; White Leghorn hens were used for comparison. Consonant with the larger adipocytes, enzyme activity was higher in the broiler-type birds.

Fatty acid binding protein in the intestine of the chicken.

The mucosa of the mesenteric intestine of the chicken has been found to contain a fatty acid binding protein (FABP) with a molecular weight of less than 12,400. The protein is present in the newly hatched chick before ingestion of feed and in the adult bird. When a low-fat diet is fed, the concentration of the FABP is highest in the proximal portion of the intestine and decreases posteriorly. When a high-fat diet is fed, an increase occurs in the amount of FABP in the lower section of the intestine.

Fat utilization in relation to intestinal fatty acid binding protein and bile salts in chicks of different ages and different genetic sources.

New Hampshire chicks utilized dietary fat more efficiently than did broiler-type or White Leghorn chicks. The difference was more pronounced with tallow than with corn oil. Utilization of fat by all three types of chicks increased until the chicks were about six weeks old. At hatching, the concentration of fatty acid binding protein (FABP) in the intestine of the broiler-type chicks was significantly less than in the New Hampshire and White Leghorn chicks. Concentration of FABP declined during the first 1 to 2 weeks of life and then increased. By four weeks of age the breed differences in concentration of FABP in the intestine were no longer apparent. At some time after four weeks of age, FABP reached maximum concentrations in the intestinal tissue of the chicks of different breeds and thereafter declined as a proportion of the total intestinal tissue. Broiler-type chicks, which did not utilize fat as efficiently as did New Hampshire chicks in the first weeks of life, displayed lower concentrations in the proximal third of the intestine and higher concentrations in the remainder of the intestine than was the case with the New Hampshire chicks. A high level of dietary fat or dietary supplementation with sodium taurocholate increased the concentration of FABP in the intestine.

Dependency of maximum goitrogenic response on some minimal level of thyroid hormone production.

Thyroidal activity was studied in chicks given dietary thiouracil in conjunction with daily doses of thyroxine and with diets adequate and deficient in iodine. DL-thyroxine administered at doses up to 1.0 microgram per day for 10 to 12 days had no effect or slightly increased thyroid weight. Both the epithelial and colloid components of the thyroid gland were increased in response to thiouracil and to thiouracil in combination with low dosages of exogenous thyroxine. Radioiodine uptake was increased above the control with thiouracil and with thiouracil in conjunction with .5 and 1.0 microgram DL-thyroxine given daily. Birds receiving thiouracil, with and without exogenous thyroxine, showed a different pattern of radioiodine uptake and release than the control birds. Thiouracil-treated birds showed a rapid uptake of iodine following its administration, which was followed by a rapid decline immediately after peak accumulation, whereas in control birds thyroidal radioiodine concentration reached a plateau at the maximum concentration attained. The goitrogenic response to thiouracil was much greater when the diet was supplemented with iodine than when the diet was iodine-deficient. Thyroids under iodine deficiency contained greater percentages of epithelial tissue than with iodine-supplemented diets. Thyroid glands of chicks given thiouracil in an iodine-supplemented diet contained much more colloid than glands from iodine-deficient chicks with or without thiouracil. DL-thyroxine at a dosage of .5 microgram per day to chicks given thiouracil in an iodine-adequate diet increased, whereas higher dosages decreased thyroidal colloid. It is concluded that some minimal concentration of thyroid hormone is required for maximum goitrogenic response. It is not clear whether the response is entirely due to an effect on thyrotropin production or whether there is an effect of thyroid hormone on the thyroid gland itself.

Mortality and production characteristics of laying chickens fed high- and low-erucic acid rapeseed oils.

Laying pullets were fed a diet supplemented with three percent of either high-erucic acid rapeseed (HEAR) oil or low-erucic acid rapeseed (LEAR) oil for 39 weeks. Egg production for the period was 78.8 and 80.1% by the birds fed the respective oils. Average egg weights were 56.8 and 58.7 g. respectively. Gains in body weight, liver weight and adrenal gland weight were similar with the two types of oil fed. Feed consumption was similar for the two groups of birds. The efficiency of utilization of the diet containing HEAR oil was accordingly lower than that of the diet containing LEAR oil. In the birds fed HEAR and LEAR oil respectively mortality attributed to metabolic disorders of the reproductive system, liver, and kidney was 3.3% and 1.2%. Mortality from other causes in the birds fed the two oils was 3.2 and 3.8% of the original populations.

The dynamics of ingested methyl mercury in growing and laying chickens.

Growing and laying chickens were fed practical-type diets containing 0, .05, .15, .45, and 1.35 ppm of mercury as methyl mercuric chloride. Chicks that had been fed mercury throughout life retained 61, 82, 91, and 95% of the mercury ingested from the respective diets at 8 weeks of age. The half-retention times of mercury, following withdrawal of dietary mercury after the 8-week period, were 8.4 and 23.4 days, respectively, for liver and kidney in chicks fed 1.35 ppm of mercury. Half-retention times in kidney and liver decreased with lower mercury intake, i.e., with lower concentrations in the tissues at the time of mercury withdrawal. Adult laying birds, continuously fed diets containing methyl mercuric chloride, laid eggs with gradually increasing concentrations of mercury until plateau concentrations reflecting the respective dietary concentrations were reached. Upon withdrawal of mercury from the diet, mercury concentrations in the eggs laid by the birds fed .05, .15, .45 and 1.35 ppm declined to reach half of the concentrations at the time of withdrawal in 17, 13, 10, and 9 days, respectively. Likewise, the half-retention time of mercury in the liver, kidney, heart muscle, pectoral muscle, and brain tissue of the adult birds depended upon the tissue concentration at the time mercury was withdrawn from the diet and was inversely proportional to initial tissue concentration according to the equation: 1n y = 1.92 - .39 1n (7 x-5), where x is the initial tissue concentration in ppm and y is half-retention time in weeks, r = -.95.

The effects of rapeseed meal fed during the growing and/or laying periods on mortality and egg production in chickens.

White Leghorn pullets of two strains were fed soybean or rapeseed meal during either or both the growing period and laying period in two separate experiments. Rapeseed meal may be fed to growing pullets at levels up to 17% of the diet without adversely affecting the subsequent rate of egg production or egg size. Birds fed laying diets containing 19% of rapeseed meal produced a greater egg mass per hen-day and gained more weight during the laying period when the growing diet contained rapeseed meal instead of soybean meal. Birds shifted at sexual maturity from soybean to rapeseed meal as dietary protein supplement undergo metabolic adjustment which retards the attainment of maximum rate of production and induces cannibalism. Both rate of production and egg size were lower when rapeseed meal constituted 19% of the laying diet in replacement of soybean meal as protein supplement. Mortality, exclusive of that resulting from cannibalism, was 4.1% and 4.6% respectively in the two experiments. Death from liver haemorrhage occurred only in birds of one strain which were fed rapeseed meal during the laying period and principally in birds which had been fed rapeseed meal during the growing period as well.

Characteristics of adipose tissue growth in broiler-type chickens to 22 weeks of age and the effects of dietary protein and lipid.

Female broiler-type chickens were fed diets containing different concentrations of protein and fat in two experiments. The first experiment was for 4 weeks. The mean weights of the abdominal fat pads were inversely related to dietary concentrations of protein between 20 and 35%. Adipocyte size and cellularity of the fat pads were lower with 30 than 20% protein. Fat deposition in the abdominal pad was increased in 3-week-old chicks by isocaloric substitution of oil for starch in the diets. At 4 weeks of age the effect of oil was not significant with 30 or 20% dietary protein (no measurements were made in chicks fed 35 or 25% protein). In Experiment 2, the development of the abdominal fat pad in birds fed 18 to 33% protein was monitored for 22 weeks. By 7 weeks the distribution of adipocyte size was bimodal. The initial adipocyte population showed comparatively little increase in numbers after 12 weeks, but cell size continued to increase. The numbers of adippcytes in the second population of adipocytes was still increasing rapidly at 22 weeks, although the size of the cells in this population remained small. At 22 weeks the small cells constituted 62% of the total adipocyte population but contained only 2.4% of the lipid in the fat pad. Adipocyte cell size was significantly affected by dietary protein and energy until 9 weeks of age, but the effects subsequently declined.