Study Looks at Group Size Effects in Furnished Cages for Laying Hens07 March 2010
The advantages of the large group size (60 hens per cage) included a greater proportion of eggs laid in the nest and more perching behaviour, and there were no effects on laying rate, feed intake or dust bathing behaviour, according to M. Guinebretiere in a paper presented at the European Symposium on Poultry Welfare last year. The provision of litter in the form of feed seemed to improve the use of the pecking and scratching area.
In the context of the Directive 1999/74/EC, M. Guinebretiere from the French agency for food safety (AFSSA) in Ploufragan explained that the trial compared furnished cages (enriched cages) in term of animal welfare, health and zootechnical performance.
In the experiment, six treatments of 18 furnished cages were compared in a 3×2 experimental trial: three group sizes with the same space per hen (small (SC, 20 hens per cage), medium (MC, 40) and large (LC, 60)), with or without litter (feed) distributed automatically on a mat in the pecking and scratching area.
The impacts of group size and litter distribution were evaluated on laying (rate, eggs laid in the nest or outside the nest), feed intake, perching and dust bathing.
The group reported that litter distribution did not influence laying rate, location of eggs nor number of hens in the nest.
Group size influenced the laying location but not the laying rate: percentage of eggs laid outside the nest was higher in SC and MC (8.4 and 4.5 per cent, respectively) than LC (3.9 per cent, p<0.01).
This was confirmed by video analyses on space occupation: percentage of hens in the nest was higher in LC (39.9 versus 25.0 per cent in SC and MC), especially during laying period (07:00 to 10:00).
Feed intake from the trough was lower for hens receiving litter (116.7 versus 119.3 g/hen/day) but the difference was only statistically significant on the first measure at 25 weeks of age, and did not persist at week 48 (109.2 versus 110.9 g/hen/day).
As the litter provided was feed, hens ate most of it, giving a higher total feed intake. The amount of feed distributed this way was around 5g/hen/day.
Percentage of hens perching at night perched was lower in SC (56 per cent) than with the other cages (60 and 67 per cent for MC and LC, respectively).
Dust bathing in the pecking and scratching area was unaffected by litter provision or group size, and neither was mortality.
The researchers report the advantages of the large group size being more frequent visits to the nest, and more eggs laid there as well as more perching behaviour (in LC and MC), without any effects on laying rate, feed intake or dust bathing behaviour.
Litter provision did not affect laying, perching or dust bathing data, except for a slight difference in feed intake, probably balanced by litter consumption for although some litter was scattered, most of it seemed to have been eaten.
General observation of the pecking and scratching area showed that occupation was high, and seemed better with litter, concluded Guinebretiere.
Guinebretiere M., D. Huonnic, M. de Treglode, A. Huneausalaun and V. Michel. 2009. Furnished cages for laying hens: effect of group size and litter provision on laying, feeding, perching and dust bathing behaviours. Proceedings of 8th Poultry Welfare Symposium, Cervia, Italy, 18-22 May 2009, p17.
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