An analysis of data for domestic pullets, turkeys, partridges and quail (Coturnix) indicates that, once all birds within a flock have become sexually photoresponsive but before spontaneous sexual development commences, mean age at first egg, egg production in a given period, mean body weight at first egg and mean egg weight increase linearly with age at photostimulation. These relationships are steeper for age at first egg in turkeys, partridges and quail, for egg production in turkeys and partridges and for egg weight and body weight in turkeys than those seen in domestic pullets. This may indicate differential responses by seasonal and non-seasonal breeding birds, species-specific factors such as geographical origins, or may reflect differing periods of artificial selection in the four species. Egg weight in domestic pullets and turkeys is significantly correlated with body weight at first egg.

This review presents findings on the influence of natural raffinose series oligosaccharides and synthetic (industrial) products on the productivity of broiler chicken. There is evidence of negative effects on animal health and productivity from the use of raffinose series oligosaccharides, but beneficial effects from synthetic oligosaccharides. Part of this contradiction may be due to differences in the chemical nature of the supplements, the level of supplementation or the duration of feeding. The future for synthetic oligosaccharides is bright, but further adoption of natural sources requires a greater understanding of their chemistry to facilitate the production of beneficial compounds and the elimination of detrimental fractions. Most current literature favours the inclusion of various oligosaccharides in the diet. The cost of production could be minimised by the use of natural ingredients which contain oligosaccharides, or by cheap synthetic products, sources of which are highlighted in this review.

Avian infectious bronchitis (IB) is a major cause of economic loss to the poultry industry. The disease, which has been identified in many areas of the world, primarily affects the respiratory tract of – usually young – domestic fowl. However, in addition to their common affinity for the respiratory tract, IB virus strains differ in their tropism for such other target organs as the female reproductive system or the alimentary tract and kidneys. The names now normally given to the disease are ‘infectious bronchitis nephritis’, ‘IB nephritis’ and ‘NIB’. These reflect its inflammatory nature and the organ primarily affected. The pathogenicity of IB virus strains varies and the severity of a disease outbreak is also influenced by the age of the birds and by environmental/management factors. In young broilers, which appear to be the type of stock most affected, the main symptoms of nephritis IB are generally the sudden occurrence of mild respiratory signs which tend to decline within a week. This is followed by a rapid rise in mortality causing the loss of 5–25% of the birds over the ensuing 10 days or so. The birds tend to die abruptly. Gross lesions are mainly confined to the kidneys. The kidney parenchyma of affected chickens is pale, swollen and mottled; tubules and urethras are distended with uric acid crystals. In pullets IB nephritis occurs principally in modern hybrid laying stocks shortly after the onset of egg production when, for several weeks, mortality is typically around 0.4% per week. Post mortem lesions resemble those found in broilers but usually visceral urate deposits are also present. Diagnosis of nephritis IB needs to include detection of IB viral antigen using immunofluorescence on frozen kidney sections and/or viral isolation and identification of IBV following standard techniques. Vaccination with the commonly used IB vaccines such as the H120 strain affords only limited protection against nephritis IB. Attention is drawn to the need for further research.

This review examines the avian heterophil leucocyte and provides a morphological and cytochemical profile drawn from light and electron microscopy studies of these cells and their characteristic cytoplasmic granules. Other aspects covered include relative and absolute heterophil counts in different avian species and the response of heterophils to stress and to acute inflammation. Heterophils are round cells and, with Romanowsky stains, their primary fusiform granules appear brick-red in colour. A secondary type of round granule, less dense in the electron microscope and smaller than the primary granule, can be seen in most avian species. The primary granules frequently display a ‘central body’ that may be proteinaceous in nature. Unlike mammalian neutrophils, avian heterophils are devoid of myeloperoxidase. However, their cytoplasmic granules contain several lysosomal and non-lysosomal enzymes including acid phosphatase, arylsulphatase, β-glucuronidase, phosphorylase, uridine diphosphate glucose-glucogen glycosyltrans-ferase, neutral and acid α-glucosidases, acid trimetaphosphatase and lysozyme. In the majority of birds heterophils are the second most numerous cell in circulation, the exceptions being several species of the Psittacine and Anseriformes orders, ostrich, ring-necked pheasant, pigeon and rosy flamingo. Heterophils generally outnumber lymphocytes in chicks between hatch and one week of age. Their numbers increase during mildly or moderately stressful conditions and consequently the heterophil/ymphocyte ratio can be used to detect the presence of physiological stress for most stressors. A heteropenia can occur, however, during severe stress. Heterophils respond to a stimulus (chemotactic agent) within about 30 minutes during the early inflammatory phase and they may also have sensitive and selective phagocytosing properties. By seven days heterophils become unrecognizable and, with macrophage recruitment, the characteristic heterophilic granuloma develops.