Breeder flocks can sometimes be very nervous, in production but especially in rearing. They tend to “fly” and react on every movement or strange sound, visitors, different clothing etc. Often this nervousness also results in feather pulling and eating, which can lead in ultimate cases to cannibalism. Once the birds are nervous and start to move into the direction of cannibalism, there is often not a lot that can be done anymore, other than dimming the lights as much as possible, use red lights in stead of white lights etc. Not all breeds and flocks show this behavior in the same way, but as it can be a serious problem and as it is often unpredictable, it is a major concern.
Although this behavior is not equal for each flock, we do see that it is often related with the feed management. Broiler breeders in rearing are restricted in their feed intake to control their body weight development, and due to that restriction they feel hunger and stress. The problem often disappears once the flock is heading towards production and gets serious feed increases, but the “learned” behavior of feather pulling and eating can stay for a long time, even if the direct cause is not there anymore.
To tackle this problem people often reduce the light intensity, use a different light color (more red), use scratch feed in the litter or even go to a form of beak treatment to reduce the negative effects.
However, if the problem is related to the feed restriction, we might have to consider the feed profile as well. As in rearing a bird needs 3 grams of extra feed for the maintenance of every 100 grams of extra body weight, it is important that the flock gets a steady increase throughout rearing of minimum 3 gram of feed per week (as the normal body weight gain is approximately 100 grams per week). If the feed increases are less, the birds will feel a “build up” of hunger over the weeks and will get more nervous.
To be able to give those steady increases it is important to restrict the feed amounts in the first weeks, to avoid overfeeding. If in this period overfeeding is done, later one the feed increases have to be reduced to control the body weights. The “hunger” feeling will increase and the birds will get nervous, but the competition will increase as well as everybody has less feed available. Because of the competition the uniformity can go down, as the “weaker” birds will have less chance. If then a system of non-feed days is introduced to allow bigger feed quantities on feed days, the birds will even get more nervous as a non-feed day is for a bird an unpredictable system.
To rear birds in a steady system without nervous behavior, it is essential to create a feed profile that allows a daily feeding system with a minimum of 3 gram increases per week (after 11 and again after 16 weeks the feed increases should even be higher than that). If a system of very small or no weekly increases is used, the birds will get nervous, and additional actions as light control, adding salt to the water, using scratch feed and even beak treatment might be needed, which will not result in a good and healthy flock.