Effects Of Dietary Vitamin C And Vitamin E On The Performance Of Laying Hens In The Humid Tropics

ABSTRACT

This study which lasted for 52 weeks investigated the effects of dietary Vitamin C (Lascorbic

acid) and Vitamin E (dl- alpha tocopheryl acetate) on the performance of laying

hens in the humid tropics. A total of 240 twenty-four week old Golden Neslink pullets were

randomly selected from a flock of 550 birds and randomly divided into sixteen treatments of

15 pullets. The birds were initially vent examined to ensure that they were at point of lay

before commencing the study. Each pullet was randomly assigned to a previously cleaned

and disinfected cage measuring 49 x 35 x 42cm at a stocking density of one bird per cage.

Four dietary levels of Vitamin C: 0, 200, 400, and 600mg Kg-1 basal diet were combined

with four dietary levels of Vitamin E: 0, 125, 250 and 375mg Kg-1 basal diet in a 4 x 4

factorial arrangement in a Completely Randomized Design. All management principles were

observed. Dead birds were promptly removed for autopsy when the need arose. At the end of

the study, three birds were selected per treatment for haematological investigation. Blood

samples were collected from the wing vein of the birds using a 3ml syringe and a 23-gauge

needle and placed in micro tubes with Ethlene diamine tetra acetic acid (EDTA) as anticoagulant

for determining the haematological values. The samples were cooled to 4 oC, using

icepacks and transferred to the laboratory within 12h of blood collection. The economic

implication of the study was then calculated. Data obtained were subjected to analysis of

variance (ANOVA) using SPSS. The mean minimum and maximum indoor temperatures

recorded during the study ranged between 18.3-25.0 oC and 27. 15-34 oC respectively while

the RH values lay between 53.0 and 88.9%. These were well outside the zone of thermo

neutrality for laying hens. Results obtained indicated that, there were highly statistical

differences (P < 0.01) between Vitamin C and Vitamin E treated birds for hen day production

(HDP), feed intake (FI), feed conversion ratio (FCR), Haugh unit score (HUS), , egg weight

(EWT) and incidence of cracked eggs. The treatment, T7 (400mg vitamin C + 125 mg vitamin

E Kg-1 basal diet) was superior to all the other treatments and had the highest values for

HDP (85.45±1.15), FI (113.15±0.56), HUS (96.27±0.47), and EWT (69.11±1.52). These

values were however, statistically similar (P > 0.05) to T8 (600mg Vitamin C + 125 mg

Vitamin E Kg-1 basal diet). The lowest values for HDP (42.33±1.43), FI (65.42±0.61), HUS

(75.50±2.10) and EWT (54.50±1.15) were observed in T1 (Controls). The synergism between

Vitamin C and E is different from the sum of the two vitamins applied separately. Loss in

body weight, incidence of cracked eggs and mortality were statistically higher (P < 0.01) in

T1 (controls) than vitamin treated birds which showed no significant (P > 0.05) differences.

With Vitamin C supplementation, birds on T3 (400 mg Vitamin C kg-1 basal diet) were

superior to T2 (200 mg Vitamin C kg-1 basal diet) and T4 (600 mg Vitamin C kg-1 basal diet).

Similarly, for Vitamin E supplementation, birds on T9 (250 mg Vitamin E kg-1 basal diet)

were statistically different (P < 0.01) from T5 (125 mg Vitamin E kg-1 basal diet) and T13

(375 mg Vitamin E kg-1 basal diet). For haematological values investigated T7 recorded the

highest values for RBC (4.11±0.15x106), Hb (8.80±0.31g/dl), and WBC (18300±519.62/mm3)

and these were statistically similar (P > 0.05) to T8 but highly statistically different (P