Choline and methionine in rations of broiler chickens

摘要

The possibility of using choline to compensate for deficiencies of methionine in rations was investigated in a trial using Broiler-6 chickens raised to 7 weeks of age under battery conditions (35/m2) with controlled temperature, humidity and light conditions. Eight groups of 100 chickens were studied. Group 1 (control) received completely balanced rations, while groups 2-8 received rations that contained minimal methionine (23.5-24% below requirements) and differing quantities of choline (0, 250, 500, 750, 1000, 1250 and 1500 g/tonne of 50% choline chloride respectively). Methionine deficiency had an adverse effect on the liveweight of chickens, with the average weight of group 2 birds being significantly lower (P<0.05) at 7 weeks (1621 g for hensand 1748 g for cocks) than that of their peers in group 1 (1765 and 1893 g respectively). The introduction of choline into combined feeds affected growth rate positively, and the average liveweights of both hens and cocks in groups 5-8 were significantly higher than those of the control group. The highest liveweights were recorded in group 7 birds (1882 g for hens, 2028 g for cocks, and 1955 g overall); this group received rations containing 1250 g choline/tonne combined feed. The use of choline was linked with small, but insignificant, reductions in feed costs. However there were no significant differences in meat yield between the groups. Levels of retinol and carotene were lowest in the liver and serum of chickens of groups 2 and 3. The addition ofincreasing quantities choline to rations stabilized retinol and carotene levels.