Component graphs $\unicode[STIX]{x1D6E4}_{0}(F)$ are defined for arrays of sets $F$, and, in particular, for arrays of path components for Vietoris–Rips complexes and Lesnick complexes. The path components of $\unicode[STIX]{x1D6E4}_{0}(F)$ are the stable components of the array $F$. The stable components for the system of Lesnick complexes $\{L_{s,k}(X)\}$ for a finite data set $X$ decompose into layers, which are themselves path components of a graph. Combinatorial scoring functions are defined for layers and stable components.

The purpose of this review is to highlight the potential of sweet potato as a feed ingredient for poultry diets. This review discusses in general the metabolisable energy value of this feed resource when compared to maize and its impact on the performance of broilers and layers fed at various inclusion rates. Trypsin inhibitors are the major anti-nutritive factor present in sweet potato; however these are eliminated with heat treatment. Nutrient profile and feeding value of different types of sweet potato meal such as potato root meal, potato peel waste, potato leaf meal and cooked potato meal are discussed. Based on feed cost, this could be an effective alternative feed ingredient in the diets of broilers and layers.

AA amyloidosis (AAA) is a disease known as amyloid arthropathy in chicken, which represents substantial economic losses, in addition to welfare concerns. Enterococcus faecalis (E. faecalis) is the major pathogen found in field outbreaks of amyloid arthropathy and its specific association with this disease has been extensively confirmed. The following review discusses the sequence types of E. faecalis associated with AAA that have been identified and characterised both poultry and humans and provide different hypotheses and theories about pathogenesis and transmission of this disease. This article covers the pathology both in field and induced cases of avian amyloidosis and concludes with approaches for a possible treatment, needs for further research and future perspectives. This paper is a consolidation of current knowledge on AAA in chickens which has been obtained over the last twenty years.

Layer breeding companies apply selection criteria to improve over 30 traits important for commercial egg production. Intensive selection for egg production over the decades has resulted in a significant reduction in genetic and phenotypic variations in egg production, however the decrease in genetic variation observed in commercial lines are not yet critical. Peak production now approaches the biological limit of one egg a day, but in early production (at sexual maturity) and late production (persistency) genetic variation is still high. Including these traits in the selection criteria will improve the egg production in commercial birds. Due to high heritability and the absence of any significant negative effects on production parameters, residual feed consumption is used as selection criteria to improve the feed efficiency. Considerable research has been carried out on egg weight, eggshell strength and internal quality of the eggs and improvements have been made as a result of selection. With the reintroduction of floor system and increased consumer interest in processed eggs, in future more emphases have to be given to the eggshell strength and internal quality of the eggs. Poultry production in the unfavourable environmental conditions of the tropics is hindered by direct and indirect heat stress leading to a general depression in performance. Results on the utilisation of naked-neck and frizzle gene in high-ambient temperatures is encouraging, and, in future, will play an important role in production of layer lines suitable for overcoming such genotype-environment interaction. Feather pecking is an undesirable behaviour, which causes major problems in non-cage systems. Several authors have identified a hereditary basis of feather pecking behaviour, which is suggested by strain differences. Hence, selection of birds with no or very low tendency to perform feather pecking should reduce the incidence. Recent molecular genetic studies resulted in identification of QTL affecting different economic traits and identification of candidate genes causing variation in performance among birds. In future these findings will play a major role in further genetic improvement of layers without any negative effect.

A rapid increase in corn use in ethanol plants, and subsequent creation of distillers dried grains with solubles (DDGS) by-products, has led to an increase in the use of DDGS in the diets of livestock. DDGS has been used all over the world as a dietary ingredient and this has necessitated more research to be conducted on its quality, nutritive values, and recommendations for feeding to poultry. Currently, there have been a limited number of research publications regarding corn DDGS as an ingredient of diets for poultry. Approximately 100 scientific papers can be found which cover a variety of topics, with various degrees of depth into each. The purpose of this review is to collate the available information to date on the application of corn DDGS as an ingredient of poultry diets that can be easily accessed by researchers and nutritionists. This review presents the current state of knowledge of nutritive values of various corn DDGS ingredients, summarizes recommendations for using DDGS in diets for laying hens, broilers and turkeys, and reports the environmental ramifications when utilizing corn DDGS in poultry feed. In spite of the great amount of variation in nutritional properties of corn DDGS originating from various sources, it has been concluded that good quality corn DDGS, especially when derived from new generation plants, can be a viable ingredient in poultry diets.

Inadequate supply, exorbitant prices and diversion towards using cereal grains for biofuel production, particularly maize, has led to a constant search for alternative energy sources for poultry and other non-ruminant species. The abundant availability of cassava in certain regions makes it a good alternative to maize and other cereal grains. Cassava root meal is rich in carbohydrate but low in protein and all other nutrients, whereas, cassava leaf meal is a moderate source of protein. Results of studies to evaluate the replacement of cereals with cassava products in poultry feed show wide variability due to differences in origin, variety, plant maturity at harvest, ecological conditions of plant growth and processing methods. Cassava products contain a wide range of cyanogenetic glycosides, particularly linamarin and lotaustralin. The level of hydrocyanic acid released from the cyanogenetic glycosides limits the utilization of cassava, but with proper processing, the dietary inclusion level of cassava meal can be increased for economic poultry production. This paper reviews the nutrient composition of cassava and its uses as a substitute for more conventional ingredients in poultry diets.