Preference, feed characteristics, and feather pecking in laying hens
Feather pecking has been controlled in the laying hen industry through methods such as beak trimming, breeding low feather pecking lines, providing enrichment items, and altering diets to promote satiety. Two recent studies have shown the positive impact of feeding silage (a relatively low nutrient feed item) in addition to (or as supplement) a nutritionally balanced hen ration in terms of decreased aggressive and feather pecking behaviour and improved feather score. The objectives of this thesis were to determine which specific characteristic(s) hens prefer, and if the preferred characteristics were responsible for improving hen welfare. Initial experiments consisted of a preference test, which provided a supplement in a removable insert in front of half a cage, and a balanced ration in the other half. In the first experiment, hens were shown to have a locational preference in the feed trough, not resulting from the presence of the insert, nor from intraspecific competition. Experiment two tested the preference for an ensiled or non-ensiled, and moist or dry material using barley greens, dried barley greens, barley silage, and dried barley silage. Results indicated that hens show preference for moist, non-ensiled materials, but ensiled materials are not rejected. Further investigations took place focusing on physical characteristics as experiment two results suggested a preference for unfermented products. Experiment three examined the provision of a forage-able substrate which was edible (wet or dry barley) or not (plastic lace), and found that edible materials increase the time spent at the feeder. Experiment four tested the preference for particle size of various edible materials (oats, silage and alfalfa) and found hens spend more time with smaller particles sizes of silage and oat materials. The final experiment (Experiment five) used a supplement with all preferred characteristics (wet pea fibre) to determine its impact on feather pecking in birds housed in conventional and enriched cages. Birds given supplemental material did not increase time spent at the feeder, and feathers showed no more or less wear than would be expected from the housing system. Vent scores (areas typically affected by pecking) tended to improve under the presence of pea fibre. Feather pecking decreased when hens were offered pea fibre when housed in large group and enriched cages. Decreased body weight, heavier gizzards, and improved feed efficiency (balanced feed per dozen eggs) point towards improved digestive efficiencies with consumed fibre, even though elongation of the ileum and jejunum seem to contradict this hypothesis. While highly preferred, moist, non-ensiled, low nutrient pea fibre did not impact hen welfare to the degree seen in previous studies with silage. However, similar feedstuffs are still a possible means of enrichment to reduce feather pecking and increase welfare in laying hens, and future research should continue with different bird strains and materials for enrichment, as well as examining hen digestive efficiencies and effects on production costs.
DegreeMaster of Science (M.Sc.)
DepartmentAnimal and Poultry Science
SupervisorClassen, Henry L.
CommitteeStookey, Joseph; Gonyou, Harold; Christensen, Dave
Copyright DateJuly 2012