The effect of dietary fibre on the small intestines and apparent digestion in the turkey.

1. In order to determine the feasibility of using high fibre diets in turkey rations, three crude fibre dietary concentrations were fed to turkey hens at three ages and performance, fibre digestibility and small intestinal morphology were determined. 2.

Performance and bone development in broiler chickens given 25-hydroxycholecalciferol.

1. A series of 5 trials was conducted with Cobb chickens in order to determine the effect of 25-hydroxycholecalciferol (25OHD3) on their performance and bone development under adequate Calcium (Ca) and Phosphorus (P) supplementation, and under moderate dietary restriction of Ca and P. Formulated beadlets of 25OHD3, trade name HY-D (IsoGen, Naperville, IL, USA) were used as the 25OHD3 source.

Metabolism and requirements for calcium and phosphorus in the fast-growing chicken as affected by age.

Three series of experiments were conducted with fast-growing chickens in order: to evaluate the effects of dietary Ca and P on cholecalciferol metabolism and expression; to determine dietary Ca requirements; to determine dietary P requirements. The results of the first series confirmed previous results on the effects of dietary Ca and P on some variables of vitamin D metabolism and expression, Ca homeostasis and P metabolism in the young chicken (1- to 21-d-old), and extended them to older birds (22- to 43-d-old). The bone formation rate and the duodenal calbindin content were maintained at high levels until the age of 43 d.

Interactions between dietary crude protein and essential amino acid intake on performance in broilers.

1. The effect of diets with increasing concentrations of crude protein at either fixed essential amino acid concentrations or at fixed essential amino acid:dietary crude protein ratios on performance was examined in 1- to 4-week-old male Cobb chicks. Increasing crude protein intakes at constant essential amino acid concentrations was carried out at two dietary energy contents.

Effect of age of turkeys on the metabolisable energy of different foodstuffs.

1. True metabolisable energy (TME) of various foodstuffs were determined in turkeys at 3, 9 and 17 weeks of age. 2.

Effect of early-stage thermal conditioning and food restriction on performance and thermotolerance of male broiler chickens.

1. The effects of early-age thermal conditioning and food restriction on performance and thermotolerance were studied in male broiler chickens, in 2 trials. 2.

Response of turkeys to relative humidity at high ambient temperature.

1. The effects of relative humidity on growth rate and thermoregulation at high ambient temperature were evaluated in turkeys. Male turkeys were exposed to ambient temperature (Ta) of 35 degrees C and relative humidity (RH) of 40% to 75% and 50% to 85%, at ages of 13 to 19 weeks (trial 1) and 10 to 15 weeks (trial 2), respectively.

Research notes: Effect of environmental temperature on broiler chickens subjected to growth restriction at an early age.

An experiment was carried out to evaluate the effect of early growth restriction (EGR) induced by feed restriction on the ability of male broiler chickens to withstand exposure to high environmental temperatures. A 2 x 4 factorial arrangement of treatments was employed to determine whether such an exposure affects the beneficial effect of EGR on performance and carcass quality. Chicks consumed feed ad libitum or were feed-restricted from 6 to 12 d of age (to achieve 60% growth of the ad libitum birds).

The effect of dietary protein level on the lysine and arginine requirements of growing chickens.

Comparisons were made of the growth and carcass fat responses to dietary lysine and of the lysine requirements of 1-wk-old broiler chickens receiving diets containing either 18, 20, 23 or 25% protein. Similar comparisons were made of the responses elicited by dietary arginine in diets containing 18 or 23% dietary protein. The responses to lysine supplementation and the lysine requirements of chicks receiving 23 or 25% protein diets were similar.

Moderate excess of dietary protein increases breast meat yield of broiler chicks.

Two factorial experiments were carried out to evaluate the effects of dietary protein level, expressed as energy to protein (E:P) ratio, on yields of carcass and breast and on abdominal fat pad weight of male broiler chicks at 43 and 57 d of age. Two diets similar in their energy content and differing markedly in their protein content, in which the E:P ratios were lower and identical to the NRC (1994) recommendations, were used in Experiment 1. Four diets, the combination of two energy and two protein levels, in which the E:P ratios were lower and identical to the recommendations, were used in Experiment 2.

The response of laying hens to induced molt as affected by strain and age.

Molt was induced in 502-d-old Lohmann, Hy-Line W-77, Yafa, and Yarkon strains of laying hens (Experiment 1), and at different ages during the 1st yr of production in the Lohmann strain (Experiment 2). The induced molt treatment included an 8-d feed withdrawal period followed by a 22-d rest period during which the birds received 60 or 70 g/d of a low-nutrient maintenance diet, in both experiments, respectively, and a reduced duration of daylight. In both experiments, induced molt resulted in an increase in postmolt egg production rate and a diminution of the rate of decline of production with age.

The response of broiler chickens and turkey poults to steam-pelleted diets supplemented with fat or carbohydrates.

The responses of growth and feed efficiency to pelleted feed was investigated in 4- to 7-wk-old broiler chickens, and in 8- to 12- and 16- to 20-wk-old turkeys. In all cases, the growth and feed efficiency responses were linear within the ranges of dietary energy tested. When energy was added by carbohydrate supplementation, weight gain and feed efficiency responses were parallel for both mash and pellets, but due to the growth response to pellets, the elevation was higher for pellets than for mash.

The response of broiler chickens and turkey poults to dietary energy supplied either by fat or carbohydrates.

The efficacy of fat and carbohydrates as energy sources was compared in 1- to 4- and 4- to 7-wk-old broiler chickens and in 16- to 19-wk-old turkeys. An increase in dietary energy by carbohydrate was made by a graded replacement of wheat bran by wheat. Energy was increased by fat through a graded replacement of soybean hulls with refined soybean oil.

Blood system response of chickens to changes in environmental temperature.

Hemodynamic changes were studied in broiler chickens during exposure to constant temperatures (10 to 35 C) or diurnal temperature cycles (10:30 C and 15:35 C), and during acute heat or cold. Packed cell volume (PCV) was significantly high at low constant temperatures (10 and 15 C), whereas at high temperatures (30 and 35 C) plasma volume (PV) was significantly high. A linear relationship between hematocrit and heart weight was observed and indicates an adaptation of heart mass to changes in cardiac output and hematocrit to meet the demands of increased basal metabolic rate.

Effects of diurnally cycling versus constant temperatures on chicken growth and food intake.

1. Male broiler chickens were exposed in separate experiments to: (a) constant ambient temperatures (Ta) ranging between 10 and 35 degrees C; (b) 12 h:l2 h diurnal high-low temperature of 10:30 degrees C, 15:35 degrees C and 15:30 degrees C in different trials; and (c) 12 h of 30 or 35 degrees C and 12 h of variable lower temperature. 2.

Responses of laying hens to forced molt procedures of variable length with or without light restriction.

The importance of the length of the rest period and of photoperiod as components of the forced molt procedures was evaluated in 650- and 560-d-old Lohman hens. The procedure included an 8-d feed withdrawal phase and rest periods varying from 0 to 35 d, during which the birds were fed for maintenance only. In the first trial, forced molt was applied with or without omission of artificial illumination.

Calcium metabolism and requirements of chickens are affected by growth.

The interaction between growth and calcium homeostasis was studied by comparing the responses of (a) fast-growing broiler chickens (Cobb) and slow-growing Leghorns, and (b) fast-growing chickens (Cobb) fed either high energy (12.13 kJ/g) or low energy (9.2 kJ/g) diets, to dietary calcium concentration ranging between 4 and 20 g/kg).

Tibia development in turkeys and chickens as affected by early-age feed restriction.

Tibia development was studied by histomorphometry in male chickens and turkeys fed ad libitum throughout the growing period, or subjected to an early-age (1-week) severe feed restriction for 6 and 14 days, respectively. In turkeys, the rates of longitudinal bone growth and epiphyseal width growth, both dependent on the activity of chondrocytes, proceeded rapidly and reached maxima at early ages of 24 and 11 days, respectively. Moreover, longitudinal bone growth and the growth of epiphyseal width were reduced during early-age feed restriction, in both chickens and turkeys.

Characterization of growth and development of male British United turkeys.

Body weight and the size of various organs (tibia, pectoral muscle, leg muscle, liver, spleen, and testes) were monitored in growing male turkeys (British United Turkeys) in an effort to characterize their growth pattern. The results were fitted with either a single- or a double-component Gompertz equation, describing single and diphasic growth patterns, respectively, using an iterative nonlinear estimation algorithm. The diphasic model with an early and a late growth component provided a better description of the body weight function than the single-phase model.

Controlled early feed restriction as a potential means of reducing the incidence of ascites in broilers.

Male broiler chicks were grown at cold temperatures to enhance susceptibility to the ascites syndrome. Various feeding regimens were used to determine whether they could influence mortality due to ascites. It was found that a precisely controlled early feed-restriction regimen at the age of 6 to 11 days significantly reduced mortality from all causes and mortality due to ascites, while maintaining optimum body weight and feed conversion at marketing age.

Skin tearing in broilers in relation to skin collagen: effect of sex, strain, and diet.

The relationship between skin tearing and collagen in broilers was investigated in two trials in which strain and sex, and strain and diet served as factorial-arranged variables, respectively. In the first trial, males and females of three strains were examined. Both skin tearing and skin collagen were significantly influenced by strain and sex without any significant strain by sex interaction.

Increased skin tearing in broilers and reduced collagen synthesis in skin in vivo and in vitro in response to the coccidiostat halofuginone.

In vivo and in vitro experiments were conducted in an effort to elucidate the mechanism of suppression by halofuginone of skin strength in broilers. In the in vivo study, halofuginone was included at concentrations of 0, 1.5, 3, and 6 mg/kg of diet, corresponding to 0, 50, 100, and 200%, respectively, of the amount recommended for use as a coccidiostat.

Response of broiler chickens and turkey poults to food restriction of varied severity during early life.

1. Cobb male (7-d-old) and female (6-d-old) chicks and BUT male and female turkeys (7-d-old), were subjected to food restriction of varying severity for 7, 5, 10 and 7d, respectively. 2.

Effect of dietary protein, energy, and feed pelleting on the response of chicks to early feed restriction.

In three trials, male broiler chicks were subjected to a 6-day feed restriction regimen designed to retard growth severely. In one trial, the amino acid requirements during refeeding were evaluated by testing the adequacy of diets based on model calculations. In two additional trials, the response of feed-restricted birds to increased dietary energy density and to feed pelleting was compared with that of birds fed ad libitum.

Severe feed restriction in pullets during the early growing period: performance and relationships among age, body weight, and egg weight at the onset of production.

The performance of egg type (Leghorn x Rhode Island Red) chickens that were feed restricted during the prelaying period was studied in two trials, each conducted with 300 hens. In Trial 1, treatments included 1) an ad libitum-fed control; 2) restriction for close to zero growth between 7 and 28 days of age; 3) the same restriction as (2) but continued by restriction of 50% growth up to 70 days; 4) restriction between 7 and 70 days for 50% growth; and 5) restriction for 50% growth between 7 and 98 days. In Trial 2, birds were restricted severely (close to zero growth) from 7 to 28 days of age, followed by restriction of 50% growth up to 28, 56, 84, and 112 days of age, respectively.