The objective of the present study was to evaluate three feed restriction programs and to study the possible effects of compensatory gain on performance, carcass characteristics and development of the organs of the digestive system, in addition to economic viability. A total of 40 crossbred (Large White x Landrace) barrows, with 67 days of age and body weight (BW) starting from 30kg which were submitted to one of the following treatments: a control, in which animals were fed ad libitum for the 86 days of the experimental trial, and the other three experimental treatments, with restriction of 20% in feed intake in relation to the control group for 21 days at 30, 50 or 70 kg (4 treatments (periods of food restriction), 5 replicates and 2 animals per pen). After the restriction period, animals were again fed ad libitum. Feed intake before the animals were fed ad libitum during the 86 days of the experiment was used as a reference for the restriction for the other animals in each experimental period. Feed intake, daily weight gain and feed conversion was calculated. Carcass characteristics were also analyzed: hot carcass weight and cold, weight gain, backfat thickness, depth of Longissimus dorsi, the quantity of meat on the carcass, area of eye-to-loin and weights of liver, stomach and small and large intestines. The cost of each dietary program was evaluated to determine its viability.
Feed conversion, considering total experimental period, for the animals kept on feed restriction from 70 kg BW was significantly lower than those animals restricted from 30kg (P<0.05) however, no differences were observed than the animals in the control group or those restricted from 50kg. The carcass characteristics evaluations and organs weights did not differ among feed restriction programs (P>0.1). The viability study showed a better economic relationship for feed restriction from 70 kg BW (0.85 $/kg of BW gain).
In conclusion, in all feeding programs, the feed restriction followed by ad libitum feeding promoted a compensatory gain effect for all treatments; however, restrictions on weights earlier undertake further feed conversion and the restriction from 70 kg body weight improved the economic efficiency of the productive process.
MV Briganó, GD Pacheco, AM Bridi, A Oba, NAN Fonseca, CA Silva. 2008. Revista Brasileira de Zootecnia, 37 (8):1398-1404.