Welfare, performance and egg quality of hens in an improved barn system
Preliminary data suggests that at 50 weeks of age, performance of layer hens were satisfactory with no marked influence of dietary treatment. Although egg weight was slightly lower than expected, values for cage systems this was considered beneficial for avoiding cloacal haemorrhage; an important precursor to vent trauma and cannibalism.
The main problem in regards to egg quality was the number of floor eggs which were reduced but remained high (11.4 and 10.6% diet 1 and diet 2, respectively) at 50 weeks of age.
This management situation needs further investigation due to egg microbial contamination. Total plumage score was substantially worsened after 40 weeks of age due to damage to the back plumage region.
Mortalities were lower than in previous years with some incidence of cannibalism at 40 and 50 weeks of age in the control diet. It is concluded that appropriate bird management during the rearing period in combination with improve dietary treatments influence performance and bird welfare in barn systems.
Studies in Victoria and Queensland have assessed the welfare and performance of barn systems with hens having with higher mortality (15-30%), lower body weight, better feather condition at 29 weeks old but inferior feather condition and cover at 40 and 64 weeks old.
Production and egg weight were lower, with more dirty eggs, with inferior yolk colour and feed intake (FI) 7-10% higher than birds kept in cages.
This overall low performance, economics, welfare and high mortality require further research.
Protein and dietary amino acids, particularly sulphur amino acids, have been shown to influence cannibalism and feather pecking (Tiller, 2004).
Tryptophan, a precursor for serotonin, promotes feelings of wellbeing, calm and relaxation in humans (South, 2004) and suppresses aggression in male broiler breeders (Shea et al., 1990), may be required at higher levels for barn birds to reduce weight loss, stress and to promote calming of birds in a stressed environment.
Selenium, an essential constituent of the antioxidant enzyme glutathione peroxidase, has been shown to improve feed conversion, feather growth, egg quality and meat quality in broilers (Edens et al., 2001). The evaluation of selenium in barn systems to improve bird welfare needs further investigation.
Another interesting aspect of the complex issue of feather pecking is pullet body weight in which undernourished birds developed pecking and cannibalism behaviour, which may be a response to locate needed nutrients (Parkinson, 2005).
The present paper reports preliminary data from a current barn production experiment in which bird management and nutritional aspects were modified and improved in order to reduce feather peaking, cannibalism and low productivity.
Bird performance at 50 weeks of age indicates that production parameters of layer hens were satisfactory with not marked influence of dietary treatment.
In the study Diet 2, which was supplemented with methionine, did not appear to influence egg weight. Linoleic acid, another dietary component, influenced egg weight.
If the birds body weight, FI and production in the present study are shown to be adequate, additional levels of linoleic acid may be needed to increase egg weight.
Although nearly 14% of eggs were laid on the litter, the proportion of dirty eggs contaminated with either soil or excreta was relatively low.
However, by increasing egg weight there is a possibility of inducing other negative aspects such as cloacal haemorrhage, an important precursor to vent trauma and cannibalism. Thus, the relatively low egg weight in the present study may be seen as a beneficial rather than a negative aspect, but more consideration and comparative studies with different levels of linoleic acid are needed.
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Article made possible through the contribution of the Australian Poultry Science Symposium (APSS) 2006.