EARLY AND LATE QUANTITATIVE FEED RESTRICTION OF BROILERS - EFFECTS ONPRODUCTIVE TRAITS AND CARCASS FATNESS

1280 female Ross 308, subdivided into 4 groups, received the same 3 di ets: starter, grower and finisher. ER and LR groups received, respecti vely from 7 to 21 and from 21 to 35 days, a daily feed amount to satis fy their metabolic requirements; the birds of the SD group were fed sk ip a day (one day fast and one day ad libitum) from 7 to 28 d; the con trol birds were fed ad libitum. At 21, 42 and 49 days feed intake, wei ght gain, feed conversion rate and mortality were calculated. At the s ame ages abdominal fat pad mass and its total lipid content were recor ded. At 49 days both the livers and samples of back skin were collecte d to evaluate their total Lipid content. The skin total protein and co llagen amounts were also determined and carcase visual scores assessed . As for productive traits, at the slaughtering age, the feed-restrict ed chickens had a good but not complete compensatory growth when compa red to the controls. The early-restricted birds showed also a better f eed conversion rate. As for carcase fatness, the abdominal fat (expres sed either in g or in percentage) of ER birds at 21 d is 1/3 less comp ared to the control. At 28 d the abdominal depot is lower for the SD b irds when compared both to the control and to the ER birds. With the r estarting of ad libitum feeding, ER birds show an increase of abdomina l fat when compared to the restricted broilers (SD and LR) maintaining , anyway, a lower Lipid percentage. At 35 and 49 days no more statisti cally significant differences appear. The skin of SD birds is signific antly less fatty than in ER and LR birds while the ER chickens achieve the best carcase visual scores. None of the subjects reared in this e xperiment suffered from fatty Liver syndrome and the total lipid conte nt of the Liver (about 4.4%) is lower compared to the values cited in literature.