Effects of Feed Restriction on Growth, Development of Ovary and Oviduct, and Mortality Rate in the Layer

Abstract

The effects of two feed restriction programs, in which the chickens were fed for 8 hours a day (8h-fed group) and fed for eighty-five percent of the amount consumed by full-fed chickens (85%-fed group), and of conventional free feeding program (ad libitum group) on growth, development of ovary and oviduct, and mortality rate in the layer were studied. The results showed that the two feed restriction programs caused a delay in growth and a deterioration in feed conversion rate. Body weight of the 8h-fed group was lower than that of the ad libitum group at 16w. (1271g VS 1384g, P<0.05) whereas that of the 85%-fed group was lower at both 16w. (1293g VS 1384g, P<0.05) and 20w (1479g VS 1550g, P<0.05). Changing a half each of the 8h-fed and 85%-fed groups to the full feeding, and a half of the adlibitum group to the 85% feeding resulted in no significant change in body weight in any but the 85%-fed group. The 85%-fed turned full-fed bird was heavier than the remained 85%-fed bird (1861g VS 1689g, P<0.05) with higher content of the abdominal fat (107g VS 39g, P<0.05). Development of the ovary and oviduct was generally depressed by the 85% feeding program, though the difference (P<0.05) was observed only at the age of 40w. The ovary weight, oviduct weight and oviduct length of the 85%-fed group were 13.0g, 22.3g, and 59.7cm. compared with 37.2g, 53.6g, and 104.0cm of the ad libitum group and 43.0g, 55.9g, and 101.3cm. of the 8h-fed group, respectively. The three groups showed a similar number of small (diameter<2mm.) and medium (diameter 2-8 mm.) follicles (P>0.05). Only the number of large follicle (diameter>8mm.) was negatively affected by the 85% feeding program. At 40 w, the average number of 1.7 units of large follicle observed in the 85%-fed group was lower (P<0.05) than 5.7 and 6.0 units found in the 8h-fed and ad libitum groups, respectively. The number was, however, increased to equality with those of the other two groups after being switched to the full feeding.