THE STUDY OF THIAMINE REQUIREMENT IN BROILER-CHICKENS

Thiamine status in response to a wide range (2 to 32 mg/kg) of dietary supplementation of thiamine was studied in male and female broiler ch ickens in order to understand the manifestation of marginal thiamine d eficiency in chickens. Thiamine content and transketolase (TK) activit y, were measured in tissues (brain, heart liver) and blood samples fro m chickens at 1, 7, 14, 21, 35, and 42 days of age. There was no corre lation between body weights and tissue thiamine or TK activity at 3 or 6 weeks of age. Overall thiamine supplementation did not have signifi cant effects on TK activity in the liver (p = 0.22) or brain (p = 0.07 ). Males had a higher concentration of thiamine than females (p < 0.00 1) in livers and brains, but the level in the heart did not differ sig nificantly between sexes. There were substantial contrasts among tissu es in changes in the tissue thiamine content in response to dietary th iamine levels. Relative to day 1, unsupplemented birds' heart, brain, and liver thiamine increased by 34, 30, and 31% respectively. In respo nse to supplementation, the heart tissue tended to accumulate thiamine at a considerably higher rate than liver or brain. Blood thiamine con centration tended to decline in unsupplemented birds and those supplem ented 2 and 4 mg/kg levels, whereas in birds supplemented with 8 mg bl ood thiamine level increased at day 7 and remained relatively constant for the remaining part of the trial. Supplementation at the levels of 16 and 32 mg/kg resulted in blood thiamine increasing throughout the duration of the trial. The presented data indicate that there are orga n specific differences in the requirement for thiamine. The heart appe ars to have a higher requirement than the fiver or brain. Since there are potential beneficial effects of thiamine on the heart, this subjec t deserves more detailed investigation.