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1. The perfusion of livers with the vital dye trypan blue was performed to test for evidence of tissue hypoxia in 3 groups of young broiler chickens, namely, ascitic, hypoxia-induced and controls.2. Hepatocytes that stained with trypan blue were considered to be dead or dying before fixation and represented damaged cells.3. The proportion of trypan blue-stained hepatocytes in the livers of ascitic birds was slightly less than half that observed in the hypoxia-induced birds but significandy more than the proportion of stained cells observed in control birds.4. Liver damage in the ascitic birds was also assessed biochemically by an altered enzyme profile.5. The study demonstrated that increased trypan blue uptake in the livers of ascitic birds reared at sea-level may be the consequence of hypoxia stress caused by reduced oxygen utilisation.

1. Cardiac troponin T is a recently developed serological marker used as a sensitive diagnostic tool for early myocardial damage in 'at risk' human patients.2. Serum troponin T values were measured in young 30-d-old broilers with ascites and in healthy age-matched flockmates.3. The data showed a significant increase (P< 0.001) in troponin T values in ascitic broilers compared with control birds. A similar increase in the arterial pressure index in ascitic birds indicated a good positive correlation at this age.4. The results suggest that this new assay cross-reacts with chicken cardiac troponin T antigen and that it may be an important indicator of myocardial cell damage for use in future genetic selection programmes in the combat against ascites.

1. Genetically fat and lean adult broiler breeder females were fed ad libitum or restricted throughout life. At one year of age, comparisons of blood viscosity and haematology and changes in blood chemistry after exposure to thermal stress were conducted.2. Whole blood viscosity was more than twice as high, and plasma triglyc-eride and haemoglobin concentrations were over 30% higher in fat line than in lean line females fed ad libitum or in restricted birds of both genotypes.3. Mean cell haemoglobin concentration was higher and mean cell volume lower in fat compared with lean line females.4. Food restriction was associated with lower plasma triglyceride concentrations, lower numbers of heterophils and monocytes and a lower heterophil-lymphocyte ratio.5. Fat line birds had a higher blood pCO2 and lower pH than lean line birds.6. Thermal stress was associated in ad libitum-fed birds with a rise in blood pH and a decrease in pCO2, and in restricted birds with a decline in blood pH and an increase in pCO2.7. Blood creatine kinase activity increased in all groups under thermal stress.

1. A factorial experiment was conducted to assess the welfare at different ages of two strains of broiler breeder and one layer strain during rearing using a range of indicators. The birds were fed ad libitum or restricted and provided with free or limited access to water.2. Food-restricted birds spent a large proportion of time scratching and pecking the litter compared with birds fed ad libitum.3. The heterophil/lymphocyte ratio and the proportion of basophils were raised at 8, 12 and 16 weeks, and the plasma concentrations of corticos-terone were higher at 8 and 12 weeks of age in restricted birds compared with those fed ad libitum.4. Creatine kinase activity was higher in broiler breeders fed ad libitum compared with layers and restricted broiler breeders. The activity of aspartate transaminase was higher in restricted layers compared with birds fed ad libitum and was similar in broiler breeders.5. Plasma viscosity was lower in food-restricted compared with ad libitum-fed birds.6. Limiting access to water had little or no effect on the welfare indicators although food-restricted birds with free access to water spent more time drinking than birds fed ad libitum.7. There were no important differences between the two broiler strains. Layers spent less time resting than broiler breeders and had higher plasma corticosterone concentrations at 3 and 16 weeks of age.8. It was concluded that there was evidence for physiological stress associated with restricted feeding at least between 8 and 16 weeks of age. It was suggested that the altered behaviour of broiler breeders kept on litter may indicate that they can cope with food restrictions and that this may be acceptable in relation to the long-term benefits of limiting body weight during rearing. The same may not be true for layers.

1. Whole blood and plasma viscosity values in normal and ascitic broiler chickens were measured.2. The mean blood viscosity value in ascitic broilers was greater than that of the controls. There was a small but significant difference in the opposite direction between plasma viscosity values of the respective groups of birds.3. Although the haematocrit and arterial pressure index values in the ascitic birds were raised, there was a fall in the concentration of total plasma protein.4. The data suggest that the raised viscosity in the ascitic birds was caused by a polycythemia and not by any influence of plasma protein.5. The cumulative effect of these factors, such as raised blood viscosity values and larger deformed red cells flowing through constricted lung arterioles, may contribute to the pulmonary hypertension and ascites seen in some young commercial broilers.

1. Storage of eggs for 14 d prior to incubation depressed hatch-ability by 10%.2. Most of the increase in embryonic mortality (64%) occurred during the first week of incubation, with a further 30% taking place during the third week.3. Chicks hatching from stored eggs did not show any increased incidence of physical abnormalities characteristic of vitamin deficiencies.4. Chicks from stored eggs showed haematological abnormalities characteristic of mild macrocytic anaemia. Such changes can result from deficiencies of folic acid or cobalamin.5. Biochemical and haematological data did not suggest impairments in the status of the chicks with respect to a range of other vitamins.

1. The plasma viscosity values of normal commercial broiler and layer strains of chicken were measured in relation to age and sex.2. In both broilers and layers plasma viscosity values decreased at 2 weeks of age; probably reflecting the period of change from maternal plasma protein to the bird's self-synthesised proteins.3. There was a progressive rise in plasma viscosity in both strains and sexes with age. The increase was greatest in female layers at 17 weeks of age before lay.4. There was no overall significant difference in viscosity values between fresh and frozen-stored plasma samples.

1. Broiler breeder females were fed ad libitum, or according to a commercial food restriction programme or to gain 0.85, 0.70, 0.55, 0.40 or 0.25 of the body weight of ad libitum-fed birds. Several indices of the welfare of the birds were assessed at 3-weekly intervals to 18 weeks of age and related to body weight by regression analysis. Results for 6, 12 and 18 weeks of age are presented in detail.2. Water intake was consistently higher in the 0.25, 0.40 and commercial restriction treatments.3. There was a negative curvilinear relationship at each age between body weight and the heterophil-lymphocyte ratio and plasma corticosterone concentration.4. There was a positive relationship between the plasma concentration of creatine kinase and body weight at 12 and 18 weeks of age. The relationships between body weight and the plasma activity of alkaline phosphatase and aspartate transaminase changed with age and there were no differences between treatments for lactate dehydrogenase.5. The time spent resting increased with body weight at each age. The relationship between time spent preening and body weight changed with age whereas that for oral activities was similar among restricted birds at 6, and among all treatments at 12 weeks of age. At 18 weeks there was an increase in oral activities with decreasing body weight.6. Fearfulness was positively related to body weight. The response of the comb to phytohaemagglutinin injection was similar in all treatments and the antibody titre to injections of sheep red blood cells was curvilinear.7. A principal components analysis of all measured traits at 6, 12 and 18 weeks of age was conducted. Most of the variables were redundant but at least one from each of the different classes of welfare indices was retained at 6 and 12 weeks of age.8. It was concluded that a body weight during rearing in the range of 0.5 to 0.85 of ad libitum might provide for optimum welfare of broiler breeder females.

1. White blood cell responses of broilers, turkeys and ducks were examined at regular intervals after being subjected to various degrees of food restriction.2. Restricted-fed broilers showed increases in heterophil and basophil numbers, together with a corresponding decrease in lymphocytes. The heterophil/lymphocyte ratio was raised. There were no differences between broiler strains.3. After only one week of feeding restricted diets, heterophils were significantly raised in selected and unselected 2-week-old ducks. At 21 weeks of age, those ducks receiving 50% of food required to achieve their ad libitum-fed body weight had raised heterophils.4. Ducks receiving food to achieve 25% of ad libitum-fed birds produced a marked basophilia, but no heterophilia.5. After two weeks of food restriction, turkeys responded with significant heterophil/lymphocyte ratios following two degrees of restricted feeding.6. It was concluded that in some poultry, a heterophilia may be the response to mild to moderate stress but a basophilia may result after severely stressing birds.

The Avian Egg: Chemistry & Biology, by R. W. Burley and D. V. Vadehra, 1989. v+472 pp. illustrated. New York. John Wiley & Sons. £66.70. ISBN 0-471-849952.A Colour Atlas of Avian Anatomy, by J. McLelland. 1990. 127 pp. illustrated. London, Wolfe Publishing Ltd. £30. ISBN 0-7234-1575-7.The Tropical Agriculturalist - Poultry, by A. J. Smith, 1990. vi + 218 pp. CTA/Macmillan, London. ISBN 0-333-52306-7.

1. Two routine staining methods for domestic fowl blood cells have been modified with superior results.2. Type of anticoagulant had a major effect on staining quality: EDTA gave excellent results whereas lithium heparin was unsatisfactory.3. Unfixed blood smears were preferred to smears fixed in methanol before staining with May Grunwald and Giemsa's stain. Intact heterophil and basophil granules were clearly demonstrated.4. Staining for 60 min in Natt and Herrick's haemocytometer diluent improved the differentiation between small lymphocytes and throm-bocytes.

1. A haematological study of the red blood cell characteristics in domestic fowls fed restricted and ad libitum diets was examined. The characteristics included Hb (haemoglobin), PCV (Packed Cell Volume), Rbc (Red blood cell count), MCH (Mean Cell Haemoglobin), MCV (Mean Cell Volume), MCHC (Mean Cell Haemoglobin Concentration) and reticulocytes.2. The investigation showed that Hb, PCV, MCH and MCV were all reduced when broilers were fed a restricted diet. The number of Rbc's in these birds also increased significantly compared with control ad libitum-fed broilers. MCHC and reticulocyte numbers did not alter significantly.3. It is proposed that some of the red cell characteristics may be restored to within "normal" ranges by food restriction. However, the results did show that there was a tendency to induce a microcytic normochromic anaemia in these restricted-fed birds.

1. White blood cells and thrombocyte values were examined in normal domestic fowls of layer and broiler strains fed restricted or ad libitum diets.2. Basophils were the only white blood cells to increase significantly in number after the period of food restriction. It is suggested that the increase may have been associated with stress.3. There were more basophils in broilers than layers, in males than females and in younger than older birds.4. In contrast, a decrease in the total number of white blood cells was seen in birds maintained on a restricted diet compared with those fed ad libitum.5. Stress may also have been responsible for an increased thrombocyte count in the restricted birds as well as a slightly lowered eosino-phil count.6. Heterophil/lymphocyte ratios were not significantly altered by the restriction of food.

Public Policy and Agricultural Technology: Adversity Despite Achievement,Edited by Don F. Hadwiger & William P. Browne, 1987. Basingstoke, Macmillan Press, with Policy Studies Organization, ix+126 pp.A Colour Atlas of Comparative Veterinary Haematology,By C. M. Hawkey & T. B. Dennett, 1989. 192 pp, illustrated. London, Wolfe Medical Publications. £40.00. ISBN 07234 09307.A Stereotaxic Atlas of the Brain of the Chick(Gallus domesticus), By W. J.Kuenzel & M. Masson, 1988. 166 pp., illustrated. Baltimore, The Johns Hopkins University Press. £44.50. ISBN 0 8018 3700 6.

1. This paper describes and illustrates the dangers of sub-optimal mixtures of EDTA anticoagulant:blood during the preparation of avian blood smears.2. Excessive concentrations of EDTA lead to variable staining and make cellular differentiation more difficult.3. It is recommended, for the use of a 2.5 ml graded blood tube containing 3.75 mg EDTA, that no less than 1.0 ml of blood be mixed.

Amino Acids in Farm Animal Nutrition. Edited by J. P. F. D'Mello. 1994. 417 pp. £55.00 Wallingford, Oxon, CAB International. ISBN 0 85198 8814Avian Hematology and Cytology. Terry W. Campbell. 1995. 104 pp. Illustrated. £48.00. Ames, Iowa State University Press. ISBN 0 8138 2970 4.