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Energy and nitrogen metabolism of diseased chickens: Aflatoxicosis a

M. A. Rajion & D. J. Farrell

a

a

Departments of Agricultural Biology, and Biochemistry and Nutrition , University of Mew England , Armidale, New South Wales, 2351, Australia Published online: 08 Nov 2007.

To cite this article: M. A. Rajion & D. J. Farrell (1976) Energy and nitrogen metabolism of diseased chickens: Aflatoxicosis, British Poultry Science, 17:1, 79-92, DOI: 10.1080/00071667608416252 To link to this article: http://dx.doi.org/10.1080/00071667608416252

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Br. Poult. Sci., 17: 79-92.

1976

Longman: printed in Great Britain

ENERGY AND NITROGEN METABOLISM OF DISEASED CHICKENS: AFLATOXICOSIS M. A. RAJION AND D. J. FARRELL Departments of Agricultural Biology, and Biochemistry and Nutrition, University of Mew England, Armidale, New South Wales 2351, Australia

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Received for publication 10th March 1975

1. New Hampshire chicks were fed on diets containing 0 (control), 0.7 (A), or 1.1 (B) ppm of aflatoxin B1. In two trials 1-d-old chicks were offered ad libitum the three diets for 14 d. The gaseous exchange of five chickens from each group was measured for 3 or 4 d, the same diets being fed, at 2, 3, 4 and 5 weeks of age in two series of experiments. The controls were fed at the lower intake of the two other groups. Following each series of experiments at the various ages, birds were starved for 24 h and their heat production was re-measured over the next 24 h. 2. Mortality was highest and growth and food conversion poorest where the diet with the highest aflatoxin concentration was fed. Mortality was confined to the first 2 weeks. 3. Performance of birds in the chambers was improved in the second series due to differences in food intake. It also improved with age suggesting some resistance to the toxin. 4. Mean respiratory quotient was 0.97 for fed chickens on diet B. This was significantly different from 0.92 for the two other groups. Similarly, during starvation the R Q was 0.76 compared with 0.73. 5. Birds fed on diet B generally grew better, retained more nitrogen and had a better energy balance in the respiration chambers than the other two groups. Metabolisability of dietary energy was less (68.5%) for all groups at 2 to 3 weeks than when older (70%) but availability of ME was the same (71%) for all groups. 6. Heat production (kJ/kg0.75) of starved birds on diet B was significantly lower than the other two groups, while endogenous nitrogen excretion was higher. 7. Water consumption (ml/g food and g/100 g body weight) was greatest for birds on diet B. 8. Although aflatoxin in the diet substantially reduced intake there was no indication that at these reduced levels of intake, nitrogen or energy metabolism were measurably impaired. INTRODUCTION

Aflatoxin is one of the most intensively studied mycotoxic diseases of livestock (Goldblatt, 1969; Detroy et al., 1971). Certain strains of Aspergillusflavus capable 79

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80

M. A. RAJION AND D. J. FARRELL

of elaborating the toxin or the toxin itself, are widespread in animal foodstuffs (Borker et al., 1966; Wogan, 1968; Bryden et al, 1975). Effects based on in vitro studies, are confined mainly to liver function and particularly; to a reduction in the rate of protein synthesis (Wogan, 1969) but there is no published evidence of effects of the toxin on energy and nitrogen (N) metabolism of chickens. It would be expected that the toxin would have profound effects on utilisation of energy and N, in view of the impairment of liver function. The main object of the present work was to investigate, using respiration calorimetry, the effects of aflatoxin on the energy and N metabolism of New Hampshire chicks. These are known to be more susceptible to the disease than other breeds (Abrams, 1965; Gumbmann et al., 1970). In the first part of the study observations were made, over a period of 14 d, on chickens given diets containing different amounts of mouldy wheat. In the second part, measurements were made, in respiration chambers, on the same chickens when aged from 2 to 5 weeks and offered the same diets. MATERIALS AND METHODS

Preparation of qflatoxin-contaminated diets

An aflatoxin-producing isolate of A. flavus, initially isolated from peanut meal, was grown on Czapek Dox agar at 25 °G for 5 d. Subsequent colonies were used to inoculate moist, sterilised wheat grains which were incubated at 25 °C for 10 d. Following the incubation period, the wheat was dried at 60 °G for 15 h, crushed and assayed for aflatoxins by the method of Pons et al. (1972). Diets

Wheat containing aflatoxin (mouldy wheat) replaced normal wheat in the control diets at two levels to give a final aflatoxin Bx concentration of 0-7 ppm (20% mouldy wheat), diet A, and 1-1 ppm (30% mouldy wheat) for diet B. These TABLE 1 Composition of the control diet

Ingredients Crushed wheat1 Soyabean meal Meat meal Vitamin-mineral supplement (g/kg) Sodium chloride (g/kg) Managanese (g/kg)

0/

/o

74 13 13 2-5 2-5

0-15

1 Crushed wheat was replaced by 20 and 30% mouldy wheat in diets A and B respectively to provide 0-7 and 1-1 ppm of aflatoxin Bx.

levels were based on aflatoxin experiments on New Hampshire chickens by Brown and Abrams (1965). The three diets had a gross energy content of 16-7 kj/g. The control diet had a protein content (N x 6-25) of 22-5%, and the 20 and 30% mouldy wheat diets had a protein content of 23-8%. The composition of the control diet is shown in Table 1.

EFFECTS OF AFLATOXICOSIS ON METABOLISM

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Feeding trials

Two feeding trials were conducted immediately prior to the calorimetric measurements and are referred to as trial 1 and trial 2. In each trial 1-d-old New Hampshire chickens from the same hatchery were used. Chickens (108) between 30 and 37 g were weighed, wing-banded and randomly divided into three equal groups. Each group was placed in a compartment in a wire-floored, electrically heated brooder and offered one of the three diets. Food and water were available at all times. Weight gains and food consumption of chickens were recorded after 7 and 14 d. At the end of this period, five chickens from each group were then selected on the basis of uniformity of body weight for subsequent measurements in the respiration chambers. Chickens that died during the feeding trial were examined for macroscopic lesions. All chickens that had been used in the respiration chambers were killed at the end of each experiment, and examined for lesions. Experiments in respiration chambers

The three indirect closed-circuit respiration chambers and details of procedures followed were described by Farrell (1972, 1974a; Walker and Farrell, 1976). Design of experiment

There were two series of experiments corresponding to the two feeding trials. Measurements were made on groups of five chickens offered the same three diets for four periods of 4 d in series 1 and for 3 d in series 2. Measurement periods commenced when the chickens were 2, 3, 4 and 5 weeks of age. Measurements made on chickens at 2 weeks of age were made again on the same group when 4 weeks of age; similarly those at 3 weeks were measured again at 5 weeks. During the time when chickens were not in the respiration chambers they were kept in cages with additional reserve birds. The group of birds on the control diet were pair-fed to the lower daily intake of the other two groups. Since all calorimetric measurements commenced on the same day, the control group was given an estimated allowance of food on day 1, an adjustTABLE2 Design of feeding and fasting experiments on groups of five chickens in respiration calorimeters at different ages

Group No.

Age (weeks) in feeding experiments 1 series 1 and 2

1 la 2 2a 1 la 2 2a

17/1—F

3

3

4 • •• 5 005, * = P

Energy and nitrogen metabolism of diseased chickens: aflatoxicosis.

1. New Hampshire chicks were fed on diets containing 0 (control), 0-7 (A), or 1-1 (B) ppm of aflatoxin B1. In two trials 1-d-old chicks were offered a...
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