In broiler breeders, while floor eggs are associated with a negative impact on hatching performance, the role of laying sequence position remains poorly understood and may contribute a further source of variation to egg quality and embryo development. Two experiments were conducted to evaluate the effects of laying environment and sequence position. In Experiment 1, eggs were classified as first collection floor eggs (FCFE) or second collection floor eggs (SCFE) and incubated to embryonic day 12 (ED12). In Experiment 2, eggs were classified as first collection nest eggs (FCNE), FCFE and SCFE to assess internal and external quality, compositional traits and eggshell mineral composition. In Experiment 1, embryos from FCFE were significantly lighter at ED12 compared with those from SCFE, despite greater initial egg size. In Experiment 2, albumen parameters differed, with first collection eggs, FCNE and FCFE, showing greater albumen weight and proportion than second collection eggs, SCFE. Shell thickness was greater in FCNE and FCFE. Mineral analysis revealed higher sodium concentrations in first collection eggs, lower zinc and molybdenum concentrations in floor eggs, reduced manganese in FCNE and higher arsenic in FCFE. Together, these findings demonstrate that laying sequence and environment alter egg composition, shell quality and mineral deposition, with egg-laying sequence demonstrating potential downstream effects on embryonic development. Improved understanding of the underlying mechanistic contribution of egg sequence to egg quality and embryo development will contribute to our understanding of achieving high and consistent hatch success in broiler breeders.

Protein content reduction in broiler breeder diets has been increasingly investigated. However, broiler breeders reared on low protein diets are characterized by a deterioration of the feather condition. Furthermore, polydipsia induced by controlled feed intake increases litter moisture and as a consequence pododermatitis. This project aimed to study the litter moisture, pododermatitis and feather condition of breeders fed with a 25% reduced balanced protein (RP) diet during the rearing and laying period over three successive generations. The experiment started with two treatments for the F0 generation: control (C) group fed with standard C diets and RP group fed with RP diets. The female F0-progeny of each treatment was divided into the two dietary treatments as well, resulting in four treatments for the F1 generation: C/C, C/RP, RP/C and RP/RP (breeder feed in F0/F1 generation). The RP diet fed breeders received on average 10% more feed than C diet fed breeders to achieve the same target BW. The female F1-progeny of each treatment were all fed with C diets which resulted in four treatments for the F2 generation: C/C/C, C/RP/C, RP/C/C and RP/RP/C (breeder feed in F0/F1/F2 generation). Litter moisture, footpad and hock dermatitis were recorded at regular intervals throughout the experimental period in all three generations. For the F0 and F1 generation, the pens of breeders receiving C diets had significantly higher litter moisture than the RP diets fed groups (P<0.05), resulting in an elevated footpad dermatitis occurrence (FDO) (P<0.05). No difference was found in the F2 generation. The feather condition was scored during the laying period for each generation. F0 and F1 breeders reared on the RP diets had poorer feather condition than those receiving the C diets (P<0.05). The C/RP breeders had a significantly poorer feather condition than RP/RP breeders (P<0.05). For the F2 generation, RP/RP/C breeders had a significantly better feather condition compared with the other three groups (P<0.05). The RP/C/C breeders were significantly better feathered than C/C/C breeders (P<0.05). In conclusion, providing RP diets to broiler breeders improved litter condition and hence reduced FDO whereas impaired feather condition. Furthermore, positive transgenerational effects of the maternal RP diets on the feather condition may be inferred, hence potentially altering the welfare status.

To ensure health and reproductive performance, broiler breeders are feed restricted during the rearing period and, to a lesser extent, during the production period. Although restricted feeding improves health and bird welfare, on the other hand the birds are chronically hungry and suffer from frustration of feeding motivation, which has a negative effect on bird welfare. The aim of the current paper is to give an overview of the role of feed (nutritional aspects as well as feeding management) as a possible tool to improve broiler breeder welfare. Possible strategies discussed are 1) dietary dilution, by reducing the energy content and/or increasing the NSP content, by adding soluble or insoluble fibres to the diet; 2) adding appetite suppressants (e.g. calcium propionate) to the diet; 3) changing feeding management (e.g., scattering feed in the litter). Some of these strategies, i.e. dietary dilution or adding appetite suppressants, positively affect behavioural patterns of the birds, by reducing stereotypic pecking and eating motivation, and increasing the time spent sitting. Appetite suppressants have however been criticised for causing birds to feel ill. These behavioural changes, however, can only be considered as indirect parameters of improved bird welfare and there is still a need for a reliable indicator of hunger. It is clear that nutritional strategies can be helpful in reducing hunger stress in broiler breeders. Nutrition, however, cannot fully solve the broiler breeder paradox. The main reason for this paradox is related to breeding goals that are focussed on improving feed conversion and increasing breast meat percentage. Future genetic selection should aim at uncoupling the link between (re)production and welfare or reducing the conflict between these outcomes.

Aggressive (i.e. over-) feeding of broiler breeder females in the period preceding onset of lay results in higher mortality and subsequent deleterious effects on egg and chick production (the ‘over-feeding complex’). An intriguing aspect of the over-feeding complex is its close parallel, albeit at a lower level, to the well known ‘Erratic Oviposition and Defective Egg Syndrome’ (EODES) obtained when feeding female broiler breeders ad libitum. This is consistent with many studies showing that partial restriction (quasi-ad libitum feeding) results in partial expression of EODES (quasi-EODES). To explain the strong deleterious effects caused by rather minor over-feeding during this critical transition period, we propose that the very severe feed restriction of the growing pullet needed to prevent the onset of EODES, combined with the genetic increase in breast meat proportion achieved by intense selection over the past two decades, results in a situation where, during the critical weeks of maturation leading up to the first egg, the body lean mass must increase greatly at the same time that the ovary is maturing. During pullet maturation, empirically determined recommended feeding plans optimally balance the need to provide the rapid increase in muscle mass needed to achieve body lean mass threshold for entry into lay, with the need to maintain the ovary in a state of sufficient restriction to avoid appearance of quasi-EODES. With feed intake delicately balanced in this manner, even minor over-feeding tips the balance in the direction of quasi-EODES resulting in the appearance of the over-feeding complex. This may have been exacerbated in the past decade by a shift in the physiological control of EODES from body weight to feed intake.

Broiler breeder hens grow more efficiently and are leaner than ever before due to positive results from broiler genetic selection strategies. Quantitative feed restriction is used to limit excessive weight gain and maximize egg production and fertility. Over the past 30 years, broiler breeder body weight (BW) targets have undergone change, although the degree of change is small compared to the large increases in growth potential. As a result, the degree of feed restriction needed to maintain broiler breeder BW targets has increased, which is a welfare concern. The objective of this study was to examine current and historical broiler breeder BW targets for three major broiler companies to assess the extent of changes in BW targets over time and to explore potential reasoning behind shifts in these growth targets. By comparing breeder parent target BW profiles with corresponding potential broiler growth, changes in the apparent severity of feed restriction of the broiler breeder of this strain were calculated. Factors affecting the interpretation of degree of restriction values were discussed in combination with current initiatives underway to alleviate the severity of feed restriction. This information is intended to demonstrate how management of broiler breeder stocks has changed in time and to provide context for a realistic measure of the degree of feed restriction in broiler breeders.

A first product of this European project was a tool for scoring chick quality. A link was established between chick quality and embryonic physiological parameters such as heat production. Eggs from broiler breeders that give rise to rapidly growing broilers have a different embryonic development that may need modified incubation conditions. Within genotypes, better chick quality induces better liveability and faster growth in broiler production. Extensive data on broiler breeder production were generated. Feed restriction was necessary to maintain welfare and reproduction at acceptable levels in standard broiler breeders. The dw-experimental genotype (E) was more tolerant to ad libitum feeding. If an alternative to feed restriction had to be found, the use of a dw genotype with less severe feed restriction could be adopted. Fibre per se, or partial feed restriction during the growing period, only compensated to a small extent for the negative effects of early fast growth on later reproduction. The results of the project on behaviour did not support welfare concerns on feed restriction. They confirmed the hypothesis that environmental pecking is a displacement activity rather than a sign of frustration. Factors other than central control by pituitary hormones seem to be involved in the modulation of the laying rate. The local (intra-ovarian) role of growth factors such as Insulin-like Growth Factors (IGFs), Bone Morphogenetic Proteins (BMPs) and leptin are known to modulate the effect of gonadotrophins on ovarian function. For both BMPs and IGFs, feed restriction enhanced the interaction between growth factors and gonadotrophins as well as the proliferation of granulosa cells in vitro. Future genetic selection of broiler breeder production might aim at uncoupling the control of growth factors in the ovary from the selection for rapid growth to maintain or increase the growth rate of chicks without further penalising the already poor reproductive performance of broiler breeders. Putative quantitative trait loci for ovulation rate were identified in the project and may eventually facilitate selection by breeding companies for birds that could be fed enough feed to optimise their welfare.

Genetic selection for growth parameters in broiler stocks has created parent stocks that are unable to self-regulate feed intake to a level that permits reproductive function. Modern broiler breeders are feed restricted to limit the incidence of reproductive disorders and excessive body weight gain. A high degree of feed restriction is common during the pullet phase, which has been identified as a welfare issue. This paper examines the productive and welfare implications of feed restriction in modern breeders and the implications of returning to ad libitum (AL) feeding conditions. Feed restricted hens are compared to ALfed hens to demonstrate the full range in potential results from eliminating or reducing the degree of feed restriction in broiler breeder management. Both full feeding and restricted feeding programmes impact bird welfare. The contrast of these methods is intended to provide background information for the development of a definition of what a normal or appropriate growth profile is for broiler breeders. The implications of overfeeding on the well-being of the birds make current feed restriction programmes the more welfare-friendly alternative, despite apparent drawbacks.

Chick quality is dependent upon conditions in the laying house, egg handling systems, and the hatchery. If any of these areas are sub-optimal, chick quality, in addition to hatchability, may deteriorate. Alternative methods to improve chick quality are warranted, especially in chicks from young broiler breeder flocks. Moreover, antibiotic compounds that improve early growth and prevent bacterial infections in broilers are becoming increasingly less available to commercial poultry producers. This paper is concerned with breeder hen nutrition as a means to improve chick quality. Published reports concerned with hen nutritional deficiencies and sufficiencies on progeny performance, rather than toxicities, are primarily discussed. The areas of protein, energy, fat, mineral, and vitamin hen nutrition that impact progeny status are reviewed. Non-nutritional substances (i.e., toxins) that impact progeny when present in the hen's diet are reviewed. Specific ingredients and nutrients fed to hens that influence progeny growth, carcass attributes, enzyme functions, and immunity are discussed.

Broiler breeders are truly caught in a welfare dilemma, because the management practices that are necessary to ensure health and reproductive competence may also result in a reduction in other aspects of welfare. In this paper I review the welfare concerns associated with feed restriction of broiler breeders. Broiler breeders show evidence of physiological stress as well as an increased incidence of abnormal behaviours, and are also chronically hungry. Alternative methods of decreasing feed intake, dietary dilution or the use of anorexic agents, are also discussed. Thus far, all of these methods have proven unsatisfactory in terms of body weight control, and in addition they do not necessarily improve welfare. Emphasis needs to continue to be placed on developing alternatives to, and modifications of, current feed restriction programmes in order to improve broiler breeder welfare. In addition, the use of genetic selection to decrease the need for restriction should be further explored.