Early‐life food restriction of broiler chickens. ii. effects of food restrictions on the development of fat tissue

Abstract

1. The physiological and metabolic effects of a short term food restriction of broiler chickens at an early age and grown to 49 d of age were examined. 2. Fat accretion was measured by tritium dilution. Adipocyte characteristics of the fat tissue were examined by cell counting after fixation with osmium tetroxide and the metabolic effects of food restrictions were measured by closed-circuit respiration calorimetry. 3. The success of food restrictions in allowing full bodyweight recovery and producing decreases in body fat was associated with a negative energy balance and a positive nitrogen balance achieved during the restriction phase. 4. Food restrictions produced decreases in body fat possibly by causing a delay in adipocyte hyperplasia. Excess dietary energy was then lost as heat until adipocyte hyperplasia re-commenced allowing the bird to store surplus dietary energy as fat. 5. A food restriction that allows full bodyweight recovery and maximum carcase fat reduction in the broiler chicken at 49 d may not be appropriate for birds grown for longer periods.

Effects of the level and duration of feeding restriction on carcass components of broilers

“…It appears that the duration of the restriction plays a role in this phenomenon, since only a short period of feed restriction had an effect on the amount of abdominal fat (Tottori et al, 1997). Our results are consistent with those of Plavink and Hurwitz (1985) and Jones and Farrel (1992). According to Plavink and Hurwitz (1985) the growth retardation of fat cells and the reduced rate of fat production by the smaller livers at the time of feed restriction is the reason that less fat will be accumulated in the carcass later.…”

“…The fat storage process and the development of body fat in broilers take place in a two-stage process (Jones and Farrel, 1992). At first the proliferation rate of fat cells is dominant; later, fat storage becomes more evident until the third week of life, in which fat storage rate becomes dominant.…”

“…Feed restriction at an early age may reduce the hepatic capacity of lipid production, which subsequently results in a lower weight of abdominal fat (Jones and Farrel, 1992). The fat storage process and the development of body fat in broilers take place in a two-stage process (Jones and Farrel, 1992).…”

“…The selection for a high growth rate is marked by increased carcass fat, increased carcass water content and increased breast muscles (Havenstein et al, 2003). In order to improve the feed efficiency and reduce fat deposition, planned feed restriction has been adopted in broiler production (Jones and Farrel, 1992;Eila et al, 2011;Mirshamsollahi, 2013). Some reports showed that early-age feed-restricted broilers did compensate for initial retarded growth and reduce carcass fat (Plavnik and Hurwitz, 1985;Leeson and Zubair, 1997;Molapo and Webb, 2014).…”

Efeito da restrição alimentar quantitativa sobre o ganho compensatório e composição da carcaça de frangos

“…Zubair & Leeson (1994) observaram ganho compensatório em aves realimentadas após período de restrição; porém, Robinson et al (1992) e Mazzuco et al (1999) não observaram o efeito do ganho compensatório, sugerindo que ele não existe. Além disso, existem diferentes opiniões sobre se o ganho compensatório é devido ao aumento de proteína (Jones & Farrell, 1992), ao depósito de gordura (Zubair & Leeson, 1996), ou à combinação destes.…”