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Dietary Changes Can Reduce Feather Pecking in Laying Hens

29 October 2008

Feather pecking in layers remains a significant problem for egg producers but a recent report from the Netherlands proposes some simple changes to the diet to reduce this behaviour, writes Jackie Linden for ThePoultrySite. In his PhD thesis, Dr Marinus van Krimpen of Wageningen University highlights how diet dilution and adding fibre in the rearing and laying feed can alleviate the problem.

"Feather pecking remains one of the major problems facing the poultry industry," explains Dr Marinus van Krimpen of Wageningen University in the Netherlands, "because it is a significant welfare insult for the hens, an economic burden for the farmer and a pressing societal concern."

Dr van Krimpen has just recently completed his PhD thesis entitled, Impact of nutritional factors on eating behaviour and feather damage of laying hens at the University of Wageningen in the Netherlands.

Jungle fowl, the ancestors of modern commercial chickens, spend around 60 per cent of their time searching for food. It is thought that feather pecking behaviour that causes so much concern today is a substitute for normal ground pecking or feeding behaviour in the absence of adequate foraging incentives because of poultryman feeds are nutrient-dense and readily available.

In his thesis, Dr van Krimpen explains that beak trimming is a common and effective precautionary measure practiced by poultry farmers - to prevent serious feather damage and mortality despite some welfare concerns associated with the procedure causing pain to the birds. It has already been banned in Norway, Sweden and Switzerland, and a ban is expected in the Netherlands from 2011.

Making the problem more pressing is the ban on battery cages that is due to come into effect in all European Union countries in 2012. Feather pecking is by no means necessarily reduced in cage-free environments.

From a literature review, Dr van Krimpen found that energy and non-starch polysaccharide (NSP) concentrations and particle size of the added NSP source reduced feather pecking behaviour in laying hens. However, these factors were often confounded in experimental diets.

So, he set the objectives of his study to examine how feeding and nutrition affect feather pecking behaviour in hens, to test whether selected nutritional changes could affect behaviour and finally, to examine carry-over effects of these factors from the rearing to the laying period.

Impact of Feeding Management on Feather Pecking in Laying Hens

A literature review revealed that specific deficiencies in layer diets are linked to feather pecking behaviour in laying hens. Severe feather pecking has been reported in birds that were fed a too low mineral level in the diet, a too low protein level or a too low amino acid level (methionine, arginine).

There appears to be somewhat more more feather pecking with diets containing only vegetable proteins compared to those fed some protein of animal origin.

Feather pecking is also more associated with diets that were restricted, coarsely ground or fed as pellets.

Feeding high-fibre diets, low-energy diets, or roughages reduced feather pecking.

Providing additional grain or straw in the litter during rearing could result in lower levels of feather pecking behaviour in adult stages.

Overall, it appeared that feather pecking was reduced when the birds spent more time feeding and foraging.

Effects of Nutrient Dilution on Feeding and Performance of Hens in Early Lay

In his first experiment, Dr van Krimpen measured the effect of dietary energy (11.8, 11.2 and 10.6 MJ/kg) and non-starch polysaccharide (NSP; 128, 146 and 207 g/kg) concentration, soluble NSP content (64 and 85 g/kg), particle size distribution of the NSP fraction (fine versus coarse) and feed form (mash versus crumbles) on feed intake, eating time and egg production of young hens aged 18 to 26 weeks.

Diets were diluted by low-NSP (sand and grit) or by high-NSP sources (oat hulls, straw, soya hulls, cellulose fibre, beet pulp and sunflower meal).

From the results, the researchers concluded that hens in early lay fed energy-diluted diets, as a result of addition of sand or grit (low-NSP) or NSP-rich raw materials (high-NSP) increased their feed intake so their feed intake and egg production were similar to the control group.

Insoluble NSP also decreased eating rate, so this could be a useful means to reduce feather pecking behaviour.

For subsequent experiments, sand was chosen to dilute the low-NSP diets, and oat hulls for the high-NSP diets.

Dietary Changes to Affect Behaviour in Hens Prone to Feather Pecking

In this experiment, effects of energy concentration, NSP concentration and particle size of added NSP source were examined separately on eating behaviour, feather pecking and hen performance of ISA Brown laying hens from 18 to 40 weeks of age.

The birds started to perform gentle feather pecking behavior during the 5th week of the rearing period. Dietary treatments did not affect maximal level of feather condition scores, but a rise of feather damage was delayed by 10 weeks in hens fed low energy, coarsely ground NSP rich diets compared to hens fed control diets.

Hens fed control NSP diets showed reduced culling rates, due to less cannibalistic pecking, if energy concentration was decreased (44.1% versus 13.1%). In high-NSP diets, however, culling rate slightly decreased when hens were fed low energy diets (31.6% versus 28.6%) (P=0.071).

Hens that were fed low energy diets compensated for 10% reduction in energy concentration by increasing feed intake by 9.3% (143.0 versus 130.8 g/d). Hen performance and body weight of the hens were not affected by dietary treatment.

It is concluded that hens that were fed low energy or high (coarsely ground) NSP diets spend more time on feed intake, compared with hens that were fed control diets. As a result, some treatments showed less feather pecking behavior.

Effects of Dietary Changes on Digesta Passage Rate and Gut Development

An experiment was conducted with ISA Brown layers from 18 to 40 weeks of age to investigate the effects of energy concentration, NSP concentration and particle sizes of added NSP on digesta mean retention time and gut development.

These findings indicated higher levels of satiety in laying hens, which may contribute to a lower feather pecking pressure.

Effects of Changes to Rearing and Laying Diets on Eating Behaviour and Feather Damage

The final experiment was set up to investigate the carry-over effects of nutrient density and NSP concentration in rearing diets on eating behaviour, feather pecking and performance in laying hens

Different levels of nutrient dilution and NSP concentration in rearing and laying diets were applied. Feed intake, eating behavior, feather pecking and development of gut segments in rearing and laying hens were measured.

Hens that were fed standard NSP diets during laying had more feather damage compared to hens fed high NSP diets (0.58 versus 0.30).

Increasing the insoluble NSP intake decreased proventricular weight and increased gizzard weight and its contents. There was a linear reduction in feather damage.

Providing diluted rearing diets increased feed intake from the first weeks of life onwards.

The researchers think it is likely that pullets were increasingly 'imprinted' on feed as a target for pecking when the diet is diluted. At the ned of the experiment, feather condition was best in those hens that had been fed the 15% diluted rearing diet.


Figure 1. Relationship between insoluble NSP intake (g/hen/d) and feather condition score



Figure 2. Relationship between feed intake (g/hen/d) and feather condition score

Practical Implications

Dr van Krimpen found that increasing behaviour related to feeding and satiety by dietary changes successfully reduced feather pecking behaviour.

It was important that the changes were made during rearing and early laying. If the birds had already developed the bad habit of feather pecking, dietary changes were ineffective.

For laying hens, nutrient dilution and addition of coarse insoluble NSP prolonged the time the birds spent feeding and slowed down their feeding rate.

Providing 15% diluted diets by 15 per cent to pullets during rearing led to less feather damage during the laying period. Dilution of the rearing diet did not affect eating time at that stage but Dr van Krimpen suggested the change may have focussed pecking behaviour at feed rather than other birds.

The factor that most affected feeding-related behaviour and satiety of laying hens was the insoluble NSP content of the diet.

Interestingly, Dr van Krimpen found that the effects of diet dilution and NSP content were additive. The best feeding strategy to prevent feather damage, he recommended, was to feed a 15% diluted diet during the rearing period, followed by a 10% diluted and coarsely ground, high-NSP diet during the laying period.

Reference

Krimpen, M.M. van, 2008. Impact of nutritional factors on eating behavior and feather damage of laying hens. PhD Thesis, Wageningen University, The Netherlands. (In English, with summary in Dutch.)

Further Reading

- You can view the full thesis by Dr van Krimpen by clicking here.


October 2008



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