Growing broiler breeder chickens are fed restricted rations to limit body weight at sexual maturity. This experiment tested a proposal (Brouns, F. et al. Applied Animal Behaviour Sciience (1994) 39, 215-223.) that feeding motivation is reduced by using qualitative rather than quantitative food restriction, and it examined relationships among suppression of growth rate, feeding motivational state and general activity level. From 2 to 15 weeks of age, female broiler breeders were reared in 6 groups of 20, each with a different feeding treatment. The 6 treatments were: high and low levels of diet dilution (600-700 g/kg and 300-350 g/kg oat feed, ad libitum), appetite suppression (50-60 g/kg and 25-30 g/kg calcium propionate, ad libitum) and quantitative restriction (recommended daily ration and twice that amount). Birds were conditioned to an operant (PR1 schedule) feeding procedure with their respective treatment diets from 3 to 7 weeks, and this was used to measure feeding motivation in 12-min tests at three times of day (10.00, 13.00 and 16.00 h) at 8, 10, 12 and 14 weeks. Proportions of time spent sitting were measured as an index of general inactivity in systematic observations at 9, 11, 13 and 15 weeks. Although the diet dilution and appetite suppression (qualitative) treatments did not limit growth rates as intended, they and the quantitative treatments produced a range of mean body weights to compare with feeding motivation whenever birds were tested. With body weight as a covariate, there were significant effects on numbers of operant responses in 12 min (the measure of feeding motivation) of weight, age, time of day and treatment x time interaction, but not treatment. Feeding motivation was positively correlated with suppression of growth rate, regardless of how that suppression was achieved. However, the experimental procedure required all test birds to be without food from 09.00 or 09.15 h, and motivation was lowest in the earliest (10.00 h) test with qualitative but not quantitative treatments. Hence, there was some evidence that feeding motivation may be partially suppressed with qualitative food restriction; distinction can be made between short-term and longer-term feeding motivation. General activity level (inversely reflected by time spent sitting) was closely correlated positively with both suppression of growth rate and feeding motivation. As a fundamental relationship between feeding motivation and reduction of growth rate was not altered by using qualitative rather than quantitative food restriction, these results support an earlier conclusion (Savory, C.J. et al. Animal Welfare (1996) 5, 105-127) that broiler breeder welfare is not improved with qualitative restriction methods.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||National Centre for Poultry Studies, Scottish Agricultural College, Auchincruive, Ayr KA6 5HW, UK.|
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