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Implications of Changing Conditions on Welfare Explored

by 5m Editor
2 June 2009, at 12:00am

Developments in the industry sometimes move ahead before the implications on bird welfare have been fully explored. Editor of ThePoultrySite, Jackie Linden, summarises two papers presented at this year's annual meeting of the UK Branch of the World's Poultry Science Association. One investigated the effects of broiler selection on feeding behaviour, and the other compared the production and welfare of two strains of hens in enriched cages.

Intensive Selection Has Not Altered Normal Feeding Behaviour of Broilers

It has been suggested that today's intensively selected broilers have altered feed intake control mechanisms, and that this could be a welfare concern because they may be constantly hungry. However, research carried out at SAC in Edinburgh, Aviagen and the University of Thessaly in Greece shows that this is not the case. There was no evidence of any fundamental changes in feeding behaviour nor any indication of birds' hunger.

Jenny Howie of the SAC presented the data from observing visits to feeders by more than 16,800 broilers aged between two and five weeks of age and from 12 batches of each of four genetic lines. The lines differed in their degree of selection for growth.

There were statistically highly significant differences (P<0.001) between the lines in term of meal size, the number of meals per day, meal duration, feeding rate and average daily intake. However, the data did not reveal evidence that birds of the more selected lines were more hungrier than the less selected, slower growing lines.

White Strains Better Suited to Enriched Layer Cages

With the bans on standards battery cages (from 2012) and routine beak-trimming (in 2011) in the European Union, egg producers committed to the industry are faced with making decisions over housing their laying hens in the future. Enriched cages, which provide hens with greater space, perches, a nest box and a scratching/pecking area are among the alteratives to conventional cages, said Dr Vicky Sandilands of the SAC in Edinburgh. She described the results of her studies, which showed that white birds performed better in the new cages.

She and her colleagues used non-beak-trimmed commercial brown and white egg layers (Hy-Line Brown and Hy-Line CV20 white strains) in 72 enriched cages in one laying house from point-of-lay to 72 weeks of age. Two different types of enriched cage were used, which differed in terms of the size and positioning of the nest box and the claw-shortening device (an abrasive strip or perforated baffle). Another variable was colony size – 20, 40 or 80 hens per cage – but these results were not presented in the paper. Two consecutive flocks were housed. Data were collected on egg production, nest box use, feather scores and claw length.

Egg production was below target for the brown birds and above the target for the white birds although this was attributed to early feed problems in one flock. There was a clear strain difference in nest box use: brown hens preferred one type of nest, while the white birds preferred the other. The brown birds were better users of the nest boxes overall.

Feather score deteriorated with age for both strains of birds but brown birds tended to have better feather cover than the white birds. Claw length was noted affected by cage type in the white birds but there was a difference for the brown birds.

Mortality was higher for the brown birds than the white ones (5.8 versus 5.5 per cent, respectively) and the brown birds showed signs of greater agression and bullying.

"In this study overall, white birds performed better in enriched cages," concluded Dr Sandilands.

May 2009