Evaluation of the Effect of Breed on Vitamin B6 Requirements of Chicks

Abstract

The vitamin B₆ requirement of the chick was studied, using weight, feed conversion, serum glutamic-oxalacetic transaminase (SGO-T) activity and gross clinical and histopathological symptoms as criteria. In the first two experiments, broiler-type chicks were fed diets containing 1.1, 2.2, 3.3, 4.4, 5.5 and 9.9 mg total vitamin B₆/kg of diet. In the third experiment, Single Comb White Leghorns, Rhode Island Reds and Vantress × Arbor Acre chicks were used to study breed effects on vitamin B₆ requirement. Chicks started on a vitamin B₆-deficient diet regimen showed retarded growth at one week of age. Clinical symptoms were first observed at about 8 days of age and were characterized by hyperexcitability, decreased appetite, extreme weakness, ruffled feathers, convulsions and death. Pathological findings revealed hemorrhages in various areas, most striking around follicles of wing feathers. Vitamin B₆ deficiency increased gizzard erosion. Histopathological manifestations of eroded gizzards were extreme dilatation of the glands of the tunica propria, with the cells lining these glands becoming almost squamous in nature. The SGO-T activity was depressed when the diet contained 1.1 mg of vitamin B₆, but was not significantly affected by levels above 2.2 mg/kg feed. The SGO-T activity in Leghorns was significantly less affected by low vitamin B₆ than in the other two breeds. For the three breeds studied, 2.2 to 2.6 mg vitamin B₆/kg ration was adequate for best growth and feed conversion. Growth was a more sensitive criterion than was SGO-T activity for vitamin B₆ adequacy.