Effects of Days after Changing Diets, Body Weight and Feed Consumption on Excretion of Taurine in Broilers.

Abstract

In order to evaluate taurine (Tau) excretion as a criterion to judge the adequacy of sulfur amino acids (SAA) of broilers, effects of dietary SAA levels, body weight (BW) and feed intake (FI) on the Tau excretion and Tau excretion/SAA intake ratio (T/S ratio) were studied using 8-day-old female broiler chicks. In Experiment 1, when the stock diet was changed to experimental diets contained 0.52, 0.82 or 1.12% of SAA, the Tau excretion remained low at 0.5μmole/day when the dietary SAA was deficient and adequate, and increased to 2.8μmole/day for 3 to 6 days on the excess SAA levels. In Experiment 2, after changing dietary SAA level from 0.81 to 1.12%, the Tau excretion remained low for 2 days, and then started to increase continuously accompanying to increase of FI, but the ratio of T/S ratio remained low until 2 day, increased suddenly by 3 day and then reached a plateau. In Experiment 3, when the excess SAA diet was supplied to the chicks with different initial BW at the same age, the Tau excretion and T/S ratio in the lowest BW group tended to be higher about 1.4 times of other groups, but not significantly.. When FI was restricted to 2/3 of the ad libitum feeding group, the Tau excretion was not affected. When FI was restricted to 1/3 of the ad libitum feeding group, BW gain decreased, and the T/S ratio increased 40 times of the ad libitum feeding group. The T/S ratio remained constant when dietary SAA levels was deficient or adequate and increased at excess SAA levels at 3 days after changing dietary SAA levels and the response of T/S ratio was kept for 10 day. These results suggested that the T/S ratio might be a useful parameter to judge that dietary SAA and SAA intake were deficient or excess.