This is a review of previously published data from experiments designed to measure the chicks' requirement for an essential amino acid in diets containing surplus protein (generally in the range 220–300 g crude protein (CP)/kg diet). The evidence shows that, within this range, the requirement for a first limiting amino acid increases nearly in direct proportion to the CP content of the diet. To explain this, the following possibilities are considered: (1) that energy supply was limiting the response to a critical amino acid, (2) that the experiments were conducted in environments which limited heat disposal by the chicks, (3) that results from the trials have been misinterpreted because growth rate rather than protein deposition was used as a response measure, (4) that the availability of amino acids in the diets was lower than had been assumed, (5) that nutrients other than the amino acid under study were limiting performance, and (6) that there was an imbalance of amino acids in the diet. It is concluded that only the last explanation fits the facts. The imbalances reported have led to a decline in the efficiency of the utilisation of the first limiting amino acid in some instances. The depressed growth observed with a high-protein diet limiting in one essential amino acid could not be attributed to lowered feed intake in most cases. The imbalance is, in these respects, different from classical imbalances which result from loading the diet with a mixture of essential amino acids. From the evidence reviewed, some doubt is cast on the validity of the dilution method for estimating amino acid requirements; nevertheless it its concluded that the dilution method remains the most trustworthy procedure for making estimates to be used in practical diet formulation. It is recommended that, in future, programmes for diet formulation should be modified to prevent surplus protein being permitted in the solution, unless a proportional adjustment is made to the minima prescribed for amino acids likely to be present in limiting proportions.

The concentrations of utilisable energy per unit of price is important information to allow choices to be made between feedstuffs for practical dietary formulations. There has been a long lasting debate as to whether net energy (NE) or metabolisable energy (ME) is preferable. Only one large data set of empirically determined net energy concentrations (NEp) of feedstuffs for poultry has been published. Although the ME system for describing the utilisable energy concentrations of feedstuffs is now widely used, different metabolised nutrients (protein, fat and carbohydrate) are utilised with different relative efficiencies for energy deposition. More recently, methods of predicting the NE of feeds from equations have been suggested. These include information on nutrient digestibility with or without determined ME values with corrections according to the efficiency by which the nutrients are utilised. The objectives of the present study were, firstly, to evaluate the relationship between determined apparent metabolisable energy (AME) and determined NEp concentrations for a range of poultry feedstuffs and, secondly, the relationship between four different NE prediction equations and determined NEp concentrations was evaluated using the same data set. There was a positive linear regression (p < 0.001) between the determined AME and NEp concentrations in a data set of 62 feedstuffs with a range of AME from 0.1 to 20.5 MJ/kg. This regression equation accounted for 92.8% of the variance in NEp. Each 1.0 MJ increase in AME gave a 0.69 MJ increase in NEp. However, this data set had a large proportion of low energy feedstuffs that are unlikely to be used in modern proprietary poultry diets. A subset of these data that included 40 feedstuffs with an AME range of 8.0–18.0 MJ/kg was also examined. The regression between determined AME and NEp concentrations in this smaller data set only accounted for 77.7% of the variance in NEp. There was evidence (p < 0.01) that AME overestimated the NEp concentrations of high protein feeds of animal origin compared with cereals, cereal byproducts and high protein vegetable feeds. Three NE prediction equations that require knowledge of the digestibility coefficients for protein, ether extract and carbohydrates all improved the precision of the NEp prediction. However, a fourth prediction equation that requires only AME and crude protein determinations gave an equally precise estimate of NEp.

A review is given on the effects of the inclusion of Jack beans (Canavalia ensifomis L. DC) in poultry diets. Their use is restricted by the presence of a number of antinutritional factors which affect performance when consumed by poultry. The principals of these are identified as concanavalin-A (a lectin), canavanine and canaline (so-called non-protein amino acids), urease and saponins. The mechanisms of their toxicity and the rationale behind the methods that have been used to detoxify Jack beans are described. These mainly involve heat processing, but other approaches such as ensiling, fermentation and addition of chemicals have been applied. It is concluded that, although substantial improvements in nutritional value can result from a number of such treatments, processed Jack beans still contain a residual toxic component which results in depressions in growth rate, food intake and food conversion efficiency when they are included in poultry diets.

Post-mortem assessment of poultry health requires both identification and classification of the severity and chronicity of lesions. Such assessments are essential for deciding the necessity for treatment or its withdrawal. Poultry meat inspection and routine necropsies are also complicated by subclinical as well as hidden inflammatory processes which result in decreased production. Measurement of changes in the plasma levels of hepatic acute phase proteins in mammalian species is known to give an indication of the stage and severity of inflammatory processes as well as identifying inaccessible lesions. For poultry, several papers have been published on the plasma changes of some acute phase proteins in association with some common poultry diseases and general inflammatory processes. Some have corresponded well with the severity and stages of lesions. It is suggested that measurement of such proteins could be used to complement routine necropsy findings. Understanding the chicken acute phase response, major acute phase proteins present, and their advantages and shortfalls as markers of inflammation, is paramount to the achievement of these goals.

This is a review of the work undertaken to establish the nutrient requirements of, and feeding practices suitable for, quail under tropical and subtropical conditions. Three types of diet are recommended during commercial rearing as follows: a starter up to two weeks of age, a grower from three to five weeks and a layer mash for birds of more than six weeks of age. For optimum growth of quail broilers, a diet containing 27% protein with 11.72 MJ metabolisable energy (ME)/kg is recommended up to two weeks of age and a diet containing 24% protein with the same energy for birds from three to five weeks. The diet for layer type starter quail should contain 24% protein with an energy concentration of 11.72 MJ ME/kg. Dietary protein contents of 20% for growers and 19% for both layers and breeders appear adequate. Experiments with particular reference to lysine, methionine, vitamin A, calcium, phosphorus, manganese and zinc were also conducted. Based on these trials and those of others, practical dietary concentrations of nutrients for various age groups and production purposes are proposed.

Battery cages for laying birds were banned in Switzerland in 1981. Several new systems were developed in the years that followed, but to date only the deep litter and aviary systems have complied with both the regulations of the Swiss Animal Welfare Act and given satisfactory production results. The ways in which layer replacements are reared has been found to be crucial if they are to be able to cope optimally with the new aviary system. For this reason, the Federal Veterinary Office commissioned a survey to investigate how layer replacement pullets were reared in Switzerland. Sixty six out of a total of 155 farms that had facilities to rear 500 or more chicks at one time were visited between April and December 1997. Data were gathered on the type of housing system, management methods and the prevalence of feather pecking. The results of the survey are presented in a descriptive way and discussed in relation to the conditions during the laying period.