density are the main aspects that can interact with the lighting program and affect the broiler’s final performance.
Low protein diets Early growth can be retarded by the restriction of intake of specific nutrients, such as protein. Broilers require 220, 200 and 180 g/kg dietary crude protein during the starting, growing and finishing periods, respectively for optimal growth. They tend to increase their feed intake to make up for deficiencies when fed with diets that are marginally defi- cient in crude protein. However, feed intake is depressed by feeding diets that are severely deficient in crude protein. Studies have shown that ad libitum feeding of a diet con- taining only 94 g/kg crude protein from 8 to 14 days de- creased the feed intake of broilers by some 57%. This de- crease in feed intake resulted in 41% growth retardation, which was not recovered after six weeks of re-alimentation.
Low energy diets Low energy diets can also be used to reduce the body weight of broilers by four weeks of age. In one study, two levels of diet ME (13.0 and 14.2MJ/kg) were used during an under- nutrition period of 6 to 12 days of age and were fed to birds at 167 KJ ME/bird/day. All growth retarded birds observed complete growth compensation by 56 days of age. Female birds, however, required less energy to recover from the lost body weight occurring during the preliminary feeding of low energy diets than did males.
Feed form The consumption of mash feed at different phases of the broiler’s growth may be employed as a method of limiting feed intake. Birds offered mash spend more time consuming their feed compared to birds fed pellets and, therefore, expend more energy in this process.
▶ POULTRY WORLD | No. 2, 2018 13
Removing feed for 8-24 hour pe- riods during the starter period has been report- ed to decrease early growth and reduce the incidence of as- cites without af- fecting the final body weight.
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