A plea to implement robustness into a breeding goal: poultry as an example

The combination of breeding for increased production and the intensification of housing conditions have resulted in increased occurrence of behavioral, physiological, and immunological disorders. These disorders affect health and welfare of production animals negatively. For future livestock systems, it is important to consider how to manage and breed production animals. In this paper, we will focus on selective breeding of laying hens. Selective breeding should not only be defined in terms of production, but should also include traits related to animal health and welfare. For this we like to introduce the concept of robustness. The concept of robustness includes individual traits of an animal that are relevant for health and welfare. Improving robustness by selective breeding will increase (or restore) the ability of animals to interact successfully with the environment and thereby to make them more able to adapt to an appropriate husbandry system. Application of robustness into a breeding goal will result in animals with improved health and welfare without affecting their integrity. Therefore, in order to be ethically acceptable, selective breeding in animal production should accept robustness as a breeding goa

Significance of chick quality score in broiler production

The quality of day old chicks is crucial for profitable broiler production, but a difficult trait to define. In research, both qualitative and quantitative measures are used with variable predictive value for subsequent performance. In hatchery practice, chick quality is judged on a binomial scale, as chicks are divided into first grade (Q1-saleable) and second grade (Q2) chicks right after hatch. Incidences and reasons for classifying chicks as Q2, and potential of these chicks for survival and post-hatch performance have hardly been investigated, but may provide information for flock performance. We conducted an experiment to investigate (1) the quality of a broiler flock and the relation with post-hatch flock performance based on a qualitative score (Pasgar©score) of Q1 chicks and based on the incidence of Q2 chicks and (2) the reasons for classifying chicks as Q2, and the potential of these chicks for survival and post-hatch growth. The performance was followed of Q1 and Q2 chicks obtained from two breeder flocks that hatched in two different hatching systems (a traditional hatcher or a combined hatching and brooding system, named Patio). Eggs were incubated until embryo day 18, when they were transferred to one of the two hatching systems. At embryo day 21/post-hatch day 0, all chicks from the hatcher (including Q2 chicks) were brought to Patio, where the hatchery manager marked the Q2 chicks from both flocks and hatching systems and registered apparent reasons for classifying these chicks as Q2. Chick quality was assessed of 100 Q1 chicks from each flock and hatching system. Weights of all chicks were determined at days 0, 7, 21 and 42. There were no correlations between mean Pasgar©score and post-hatch growth or mortality, and suboptimal navel quality was the only quality trait associated with lower post-hatch growth. Growth was clearly affected by breeder flock and hatching system, which could not be linked to mean Pasgar©score or incidence of Q2 chicks. Q2 chicks showed lower post-hatch growth compared to Q1 chicks but effects on flock performance at slaughter weight were limited because early mortality in Q2 chicks was high (62.50% at 7 days). We concluded that chick qualitative scores and the incidence of Q2 chicks may be informative for the quality of incubation, but are not predictive for post-hatch flock performance. Culling Q2 chicks after hatch is well-founded in terms of both animal welfare and profitability

Effects of genetic background and social environment on feather pecking and related behavioural characteristics in laying hens

Woldwide, but especially in Europe, poultry husbandry will undergo significant changes due to the prohibition of both battery cage systems and beak-trimming. In laying hens, these changes will increase the risk of feather pecking. Feather pecking is defined as the non-aggressive pecking towards the plumage of other birds. It may result in feather damage and mortality due to cannibalism, which can be considered the ultimate phase of severe feather pecking. Feather pecking may therefore have negative consequences for bird welfare and the economic situation in poultry industry. To gain further insight in risk factors related to feather pecking, this thesis investigated the effects of genetic background and social environment on feather pecking and related behavioural characteristics in laying hens. In several experiments, behaviour, performance and physiology of cage-housed birds from pure-bred genetic lines was studied in different social environments at different ages. Results indicated that birds from different purebred lines show differences in feather damage due to severe feather pecking (an indicator for feather pecking) and in their response towards a novel object. This indicates that it is possible to select against high levels of both feaher pecking and fear related behaviour. The tendency to develop feather pecking was also related to the response towards a novel object, although this relation differed between birds from different backgrounds and from different ages. Other results showed that the response in the novel object test was also related to performance, which should be taken into account if such a test would to be used in a breeding program. Feather pecking and fear related behaviour were also affected by group mates (social environment): non-fearful birds became more fearful in presence of fearful birds. This effect could only be established at 18, but not at 5-6 weeks of age. At adult age, fearful birds showed more feather damage in presence of non-fearful birds, whereas the social environment during rearing had no effect on the occurrence of feather pecking. This indicates that fearful behaviour predisposes adult birds both to more easily develop and to be targeted by feather pecking. The changes in social environment were, however, not accompanied by physiological changes in brain serotonine or dopamine activity. These neurotransmission systems have been related to feather pecking. Results did indicate that the role of serotonin uptake does require further attention. According to the results from this thesis, laying hens should be kept in behavioural uniform groups to minimize the damage due to feather pecking. Additionally, reducing the expression of feather pecking could be achieved by breeding against expression of fearful behaviour, but possible correlated changes in performance should be accounted for. It remains to be investigated how the results with respect to social environment can be translated towards more extensive systems, such as floor-housing. <br/

Sow behaviour during parturition in relation to the observed and the genetic merit for weaning survival .

The sow's breeding value for mothering ability (EBVma) can be estimated as the genetic effect of the foster sow on piglet survival at weaning. Sows with a high EBVma have litters with a short average interval from birth until first colostrum intake. In the present study, it was investigated whether sows with a high EBVma show differences in maternal behaviour during parturition. It was hypothesized that during parturition, sows with a high EBVma and/or weaning survival were less active (increased durations of lying laterally and lying ventrally, decreased durations of standing and sitting and less postural transitions) than sows with a low EBVma. These behaviours were observed from birth of first piglet until birth of last piglet using 25 sows with known EBVma. It was found that during parturition sows with high weaning survival showed longer durations of sitting and shorter durations of standing than sows with low weaning survival. These results indicate that maternal behaviour during parturition has an effect on piglet survival at weaning. No effect of EBVma on maternal behaviour during parturition was found. In conclusion, EBVma of sows did not show a relationship with their maternal behaviour during parturition. This would suggest that the previously found difference in interval until first colostrum intake of piglets from sows with varying EBVma, is not related to differences in maternal behaviour during parturition, although this should be specifically tested in future experiments. The results from this study can be used as a starting point for future research to eventually provide breeding companies with tools to select sows for pre-weaning survival of piglets

The effects of selection on low mortality and brooding by a mother hen on open-field response, feather pecking and cannibalism in laying hens

The aim of the present study was to investigate the effects of selection on low mortality in combination with brooding by a mother hen on open-field response at 5-6 weeks of age and on plumage and body condition at 42 weeks of age. Birds in the experiment were either selected for low mortality in group housing (low mortality line) or randomly selected (control line) for two generations. These lines originated from the same population. Twenty groups of 10 female birds from each line were used. Within each line, ten groups were brooded by a foster mother and ten groups were non-brooded. At 5-6 weeks of age, the chicks were tested in an open-field test for five minutes. At 42 weeks of age, plumage condition and incidence of comb lesions and toe wounds of all birds was recorded. It was found that both brooded chicks and chicks from the low mortality line were more active in the open-field test at 5-6 weeks of age, indicating that they were less fearful or had a stronger exploratory motivation. No interactions were found between selection on low mortality and brooding. Birds from the low mortality line also had a lower incidence of comb and toe wounds compared with the control line at 42 weeks of age. No effect of brooding on plumage condition or incidence of wounds was found. This study indicates that selection on low mortality is a promising way forward to reduce maladaptive behaviour in laying hens, especially if such an approach is combined with improved rearing condition

Hen die tegen een stootje kan (interview met naam geïnterviewde)

Hendrix Genetics en Wageningen UR onderzochten hoe de 'zelfredzaamheid' van leghennen te verbeteren is. Aan ISA, de leghennenfokkerij van Hendrix Genetics, de taak om dat toe te passen in het fokprogramm

Mixed housing of different genetic lines of laying hens negatively affects feather pecking and fear related behaviour

Adult laying hens from Rhode Island Red (RIR) origin both express lower levels of feather pecking and lower fear responses towards a novel object than laying hens from White Leghorn (WL) origin. The present study investigated whether mixed housing of RIR and WL laying hens would affect their behaviour in both an open field (at 17¿18 weeks of age) and manual restraint test (at 24 weeks of age) and their feather damage due to severe feather pecking. In experiment A, `pure¿ groups contained birds from one line only throughout the rearing and laying period. `Mixed¿ groups contained an equal number of RIR and WL birds. Pure and mixed groups contained four birds, which were housed in battery cages. It was found that RIR birds were more active in the open field and manual restraint test than WL birds, although RIR birds from mixed groups became less active in the open field test than RIR birds from pure groups. This would indicate that RIR birds were less fearful than WL birds, but that they became more fearful in presence of these WL birds. In experiment B, RIR and WL birds were only housed together during the laying period, in varying ratios. It was found that WL birds from mixed groups had more feather damage due to severe feather pecking than WL birds from pure groups, whereas no effect of mixing was found in RIR birds. RIR birds from mixed groups therefore appeared to have developed relatively high levels of feather pecking, targeted at WL birds. This would indicate that, together with results from experiment A, fearful RIR birds from mixed groups were at higher risk to develop feather pecking than less fearful RIR birds from pure groups. This study clearly demonstrates that social factors have a strong influence on the development of feather pecking and related behavioural characteristics

Selection method and early-life history affect behavioural development, feather pecking and cannibalism in laying hens: A review

The aim of this review is to discuss the effects of selection method and early-life history on the behavioural development of laying hens. Especially in larger groups, laying hens often develop damaging behaviours, such as feather pecking and cannibalism, leading to impaired animal welfare. We hypothesise that the propensity to develop feather pecking and cannibalism is affected by a bird's genetic background and by its early-life history. The genetic background can be influenced by genetic selection. Laying hens are traditionally selected on individual performance, which may lead to co-selection of feather pecking and cannibalism. For hens kept in small groups, it has recently been demonstrated that a novel group selection method, focusing on group performance, can help to reduce cannibalism. However, the biological background behind the success of group selection is unknown. It is also not known whether these results from small groups can be translated to larger groups of laying hens. Regarding early-life history, laying, brooding and rearing conditions have been shown to have major effects on behavioural development and on feather pecking and cannibalism. The presence of a hen during rearing has been shown to improve foraging- and social behaviour, to decrease feather pecking and to decrease fearfulness in chicks. Applying group selection and rearing laying hens in a more natural environment may be key factors in solving the problems caused by feather pecking and cannibalism, especially if the promising results of group selection from small groups in experimental settings can be translated to large-group housing systems