severe- birds get ~30% of ad lib intake during rearing
birds cont. hungry: highly active, highly motivated to feed at all times (operant feeding tests showed that motivation to eat is 3 tims greater than that of unrestricted birds subjected to 72 h food deptrivation)
exhibit oral stereotypies related to frustration of feeding motivation (spot pecking at non-food objects, polydipsia- over drinking)
commercial food restriction contravenes " freedom from hunger and thirst"
how much hunger is acceptable? can we meausre hunger?
% of ad lib intake
behaviour- food searching, activity
plasma glucose/non-esterified fatty acids
feed of feeding (limited by crop)
compensatory feed intake
operant techniques (measure motiviaton)
Types of food restriciton
quantitative: provide less of high quality food
qualitative: provide more food w/ lower energy content (high proportion of indigestible fibre in food)
does qualitative restriction improve welfare?
some evidence for benefits (increased satiety, reduced stereotypic behaviour)
more difficult to control growth rate
feeding motivation and activity level related to growth rate suppresion (regardless of how achieved)
qualitative restriction has only limited scope to improve broiler breeder welfare