Light patterns have less effect on numbers of eggs laid by current stocks than on those of forty years ago, but the principles have not changed. Ovarian activity is stimulated by increasing photoperiods and suppressed by decreasing photoperiods. The light pattern used during rearing can still have large effects on age at 50% lay, even for modern stocks. Early sexual maturity maximises egg numbers but gives smaller eggs. Late maturity maximises egg size at the expense of numbers. The relationship between egg output (g/hen d) and age at first egg is curvilinear, with maximum yield occurring in flocks maturing in about the centre of their potential range. Fancy patterns of increasing daylength after maturity are probably not justified. A flock held on a constant 14h day will lay as many eggs as one given step up lighting.

Intermittent lighting saves about 5% of feed consumption with no loss of output, provided that the feed has adequate amino acid content to allow for the reduced feed intake. Producers with light-proof laying houses should be taking advantage of intermittent lighting.

The recommended light intensity for laying houses is still 10 lx, although the physiological threshold for response to changes in photoperiod is closer to 2 lx. Very dim (0.05 lx) light filtering into blacked out houses will not stimulate the hypothalamic receptors responsible for photo-sexual responses, but may affect the bird's biological clock, which can alter its response to a constant short photoperiod. Feed intake shows a curvilinear dependence on environmental temperature. At temperatures below the panting threshold, performance can be maintained by adjusting the feed so as to maintain an adequate intake of critical amino acids. Above the panting threshold, the hen is unable to take in enough energy to maintain normal output. There is no dietary modification which can effectively offset this problem. Diurnally cycling temperatures result in feed intake and egg production equivalent to that observed under a constant temperature equal to the mean of the cycle. When the poultry house is cooler at night than by day, it helps to provide light so that the birds can feed during the cooler part of the cycle.

For 16 weeks, turkeys were fed the following feed mixtures: control diet without antibiotic (or inulin), diet with flavomycin (8 mg/kg) and diets with different level of inulin: low (0.1% for 16 weeks), medium (0.4% and 0.2% in the first and second 8-week period, respectively) and high (1 % and 0.4% in the first and the second 8-week period of the experiment). During the first 8 weeks, dietary intake and feed conversion were similar in all groups. A high content of inulin in a diet caused lower body weight gain of turkeys compared to the remaining groups. In this period coefficients of protein digestibility (85.7-86.8%), concentration of dry matter and ammonia in faeces were alike in all groups. Faeces of turkeys fed a diet supplemented with inulin were characterised with a lower pH (5.48-5.56) than these of turkeys from the control group (5.77) as well as with lower activity of microbial β-glucuronidase (0.52-0.79 U/g and 1.01, respectively). The lowest faecal β-glucuronidase activity was in group with flavomycin (0.44). The addition of an antibiotic or inulin did not increase the final body weight of the turkeys; moreover the birds fed with the highest dose of inulin were the lightest. The influence of the experimental diets on ileal parameters was low; they affected however functioning of the caeca. The share of flavomycin in the mixture lowered the activity of microbial α-glucosidase, to some extent enhanced pH of digesta, but did not lower SCFAs concentration. As a result of increased amount of caecal digesta, the total sum of SCFAs produced was higher than in the control group. Higher doses (0.4/0.2% and 1.0/0.4%) of inulin in a diet caused a beneficial pH decrease in digesta (6.84 and 6.92, respectively), compared to lower doses of this preparation (7.12). On the other hand, they evoked a disadvantageous increase in the ammonia concentration in the caeca (1.188 and 1.240 mg/g in digesta of groups Inulin-M and Inulin-H, compared to 1.109 mg/g in digesta of group Inulin-L). Increasing the inulin dose in a diet up to 1% did not increase the activity of microbial enzymes, while increased significantly the concentration and amount of SCFAs in the caeca compared to limited dose (0.1%) of inulin preparation.

Digestion of starch is effected by hydrolysing enzymes in a complex process which depends on many factors; these include the botanical origin of starch, whether the starch is amorphous or crystalline, the source of enzymes, substrate and enzyme concentration, temperature and time, as well as the presence of other substances in the multicomponent matrix in which starch occurs naturally, e.g. cereal grains. Native starch is digested (i.e. hydrolysed) slowly compared with processed (gelatinised) starch whose crystallinity has been lost and where the accessibility of substrate to enzymes is greater and not restricted by α-glucan associations such as double helices (especially in crystallites) or amylose-lipid complexes (in cereal starches). The restriction of starch digestion (primarily in the human digestive system) due to forms which are resistant to hydrolysis has led to the concept of dietary ‘resistant-starch’. Different forms of resistance can be identified which hinder hydrolysis. With regard to digestibility, whether in the human or animal digestive tract, it is important to understand the mechanisms of enzymatic hydrolysis, and the consequence of incomplete digestion i.e. the potential loss of glucose as a valuable source of energy. This review deals with starch hydrolysis by specific amylases in model (in vitro) and more broadly in in vivo systems. The optimisation of starch hydrolysis and digestion is discussed in the light of modern knowledge.

The United States (U.S.) poultry industry continues to implement induced moulting to extend egg production in commercial laying flocks. Achieving an optimal moult requires dietary manipulation to cause a complete regression of the reproductive organs and cessation of egg production. This is followed by rejuvenation and initiation of an additional egg laying cycle. Currently feed withdrawal is the primary means to initiate moult and is regarded as an optimal approach for achieving post-moult performance. However, removal of feed can lead to potential physiological stress in laying hens as well as an increased susceptibility to Salmonella enteritidis colonization and invasion. To retain the ecological benefits of induced moult will require development, testing and implementation of alternative dietary approaches that minimizes these problems and increase the egg production and egg quality benefits associated with the additional egg laying cycles. Strategies for accomplishing this are discussed.

Force-feeding is a very old practice, first recorded in ancient Egypt, but until the 1950's foie gras production remained somewhat limited in volume. Foie gras is currently produced in various countries but approximately 80% of world production and consumption takes place in France.

Geese, which were the most common specie been force-fed until recently, now account for less than 10% of the total world foie gras production. Ducks such as the Muscovy duck (Cairina moschata) account for less than 5%, and mule ducks for the rest. Thus, over 35 million mule ducks were force-fed in France in 2001, accounting for nearly 95% of the domestic foie gras production. This increase was made possible by technical progress in specific breeding programmes and force-feeding practice.

However, the future of this production is uncertain, at least in Europe. Indeed, although a number of experimental approaches have shown that there is no scientific evidence that validates such adverse comment, this procedure is highly criticised in terms of animal welfare. The Council of Europe therefore adopted two specific recommendations in 1999 and although its practice is not banned at present, it is limited to the areas where it is already practised and only under specific rearing conditions. Therefore, the question is: will it be still possible to produce foie gras in France or elsewhere in Europe in the future and, if not, where and how will it be produced?

Bacteria in nature appear as diverse communities, which may comprise of hundreds of different species. The shared capacity of the bacterial communities to adapt in any imaginable set of conditions is remarkable. Many bacteria have growth requirements, as yet undiscovered, which are fulfilled by their natural habitats. Indeed, bacterial communities have members specialized on different functions and providing vital elements to other bacteria living in the same community. Therefore, most bacteria cannot easily be isolated from their habitats by the routine culturing methods used in most laboratories today. To overcome the difficulties in culturing of individual microbes, modern approaches analyse the structure of bacterial communities by determining the characteristic features of the microbial DNA extracted from the community samples. Using such techniques we have found that 90% of the bacteria in the chicken gastrointestinal tract represent previously unknown species. Furthermore, more than half of the 640 different species found represent previously unknown bacterial genera. Bacteria in the gastrointestinal tract derive most of their carbon and energy from dietary compounds which are either resistant to attack by digestive fluids or absorbed so slowly by the host that bacteria can successfully compete for them. The performance improvements on use of a growth promoting feed antibiotic is due to factors such as reduced competition for nutrients in the small intestine, reduced local inflammation due to control of pathogens, and reduced size of intestine. Since bacterial species differ in their substrate preferences and growth requirements, the chemical composition and structure of the digesta largely determines the species distribution of the bacterial community in the gastrointestinal tract. Consequently, it should be possible to shift the microbial community from harmful to non-harmful bacteria by changing the diet.

Formal knowledge about traditional free-range chicken production in tropical countries is increasing but still limited. However, it appears from literature studied connection with these studies, that management, and thus production performance, in general is comparable in different countries and affected by similar factors. Further, poultry production has shown to be a very important income generating activity, predominantly run by women. On the basis of three studies (A, B and C), the paper describes local chicken production in a communal area of Zimbabwe and highlights production characteristics. Study A is an investigation of the management and production through questionnaires and semi-structured interviews. Study B is a phenotypic description of 360 chickens and a description of feed availability. Study C is records of production during 6 months. Findings confirmed that women owned most chicken flocks and that income generated from chicken production was spent to better nutrition, health and education of the family. High mortality and slow growth were, by farmers perceived to be the major constraints to production. This was supported by production records, which showed that survival among young chickens was low (45% until 16 weeks of age). Most deaths (69%) occurred during the first 3 weeks after hatching. Most common mortality causes were diseases, predation, external parasites and accidents. Few clutches per hen per year with long brooding periods resulted in low production of chickens ready for slaughter or sale. Growth rates until 10 weeks of age were just over 6 g/day. Production results are discussed in relation to other literature.