Effect of Restriction of Feeding Time of Extremely High or Low Energy Diet on the Growth of Chicks

Abstract

Two experiments were carried out to study the effect of various programmes of restricted feeding. In Expt. 1, 168 7-week-old White Leghorn male chicks were reared on 14 different feeding programmes for 48 days, then all the chicks were full-fed the well balanced control diet for 28 days. In Expt. 2, 28 4-week-old White Leghorn male chicks were fed the control diet on one of 3 programmes of full-feeding or 2 restricted feedings for 15 days, then half of the chicks on each programme were sacrificed for carcass analysis. Thereafter, all the rest were fed the control diet freely for 6 days and sacrificed for carcass analysis.Following conclusions were induced from the results obtained:1) When fed ad libitum every day, growth rate of chicks on either high or low energy diets was retarded signficantly.2) When fed the diet of moderate or higher energy level, i.e. 2.7kcal metabolizable energy/g or higher, the chicks approximately kept the body weight on the programme feeding every 3rd day, but the chicks fed the diet every 4th or 5th day could not survive longer than 13 days. The chicks fed low energy diet every 3rd day also could not survive.3) On the programme of feeding for only 3 hours per day, it was necessary to feed every day, since no chicks survived when fed every other or every 3rd day.4) Regardless of the difference in resticted feeding progammes and dietary energy levels, significant linear relationship existed between energy intake per bird and growth rate of the chicks fed the diets of similar protein level. (Fig. 2)5) When chicks reared on restricted feeding programmes were switched to full feeding of well balanced diet, body weight recovered very rapidly and efficiently. Significant negative correlationship was observed between body weight gain during this recovery period and the body weight at the end of restriction period, i.e. strength of the restriction. Since feed intake of the chicks in the recovery period was only slightly different from each other, significant negative correlationship was also observed between feed efficiency (gain/feed) during the recovery period and the strength of the restriction.6) Response in feed intake of the chicks to the change in dietary energy level was much slower than that to the change in mechanical restriction of feeding time of the diet.7) Carcass fat content decreased by the restricted feeding of the control diet and increased when switched to full-feeding, while actually no change was observed in carcass protein content by the restricted feeding. Efficiencies of retention of both carcass fat and protein in the recovery period, indicated as g of retained fat per 1, 000kcal of metabolizable energy intake and g of retained protein per g of digestible crude protein intake, respectively, were significantly higher in the chicks reared on severe restricted feeding programme than those in the chicks full-fed.