Feed-restricted broiler breeders: State-dependent learning as a novel welfare assessment tool to evaluate their hunger state?
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This paper reports three experiments that aimed to validate the use of state-dependentlearning (SDL) as a novel welfare assessment tool to evaluate the hunger state of feed-restricted broiler breeders.In each experiment, birds alternated every 2 days between two food rations: quantitativefeed restriction (QFR) and ad libitum access to the same feed (AL). Each food ration waspaired with a different, end of day, coloured food reward. It was predicted that the rewardassociated with hunger (QFR FR) would be preferred to the food reward associated with AL(AL FR) in a subsequent choice test. The SDL preference testing took place after 4 and 8 daysof training. Each bird was tested twice (once per food ration fed on the test day).In experiment 1 (pilot, n = 4), birds preferred the QFR-associated reward during both tests(mean (±S.E.M.) preference: QFR FR: 35.0 (±3.5) g; AL FR: 2 (±1.3) g, but differential foodreward intake between hunger states during training confounded the results.In experiment two (n = 12) a smaller food reward was used during training to try andequalise intake. The birds preferred the QFR FR in test 1 only (least significant differ-ence (L.S.D.) = 15.08, P < 0.05). The mean (±S.E.M.) consumption in test 1 was: QFR FR: 31.6(±4.3) g; AL FR: 9.41 (±2.3) g. However, differential reward intake continued to confoundthe findings.In experiment three (n = 8), the food reward was made more palatable by feeding moistand food reward intake during training was equalised between hunger states. During test-ing, birds continued to show a significant preference in test 1 only (L.S.D. = 13.73, P < 0.05).It was concluded that SDL-derived preferences observed do exist but are not a robustphenomenon. Therefore, further research is needed to quantify factors influencing SDLdevelopment and maintenance before using SDL as a tool to assess hunger in feed-restrictedbroiler breeders.© 2015 Elsevier B.V. All rights reserved.
Journal Title/Title of Proceedings
Applied Animal Behaviour Science
Copyright © 2015 Elsevier B.V. All rights reserved. This is the author’s version of a work that was accepted for publication in Applied Animal Behaviour Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Animal Behaviour Science, [165, April 2015)]DOI: 10.1016/ j.applanim.2015.01.006