Project Abstract

Abstract
The humid tropics present unique challenges for poultry production, including heat stress and increased susceptibility to diseases. In such environments, the performance of laying hens can be significantly affected. This study aimed to investigate the effects of dietary supplementation of vitamin C and vitamin E on the performance of laying hens in the humid tropics. A total of 240 laying hens were randomly assigned to four dietary treatment groups control (basal diet), vitamin C supplementation, vitamin E supplementation, and a combination of vitamin C and vitamin E supplementation. The trial lasted for 12 weeks, during which various parameters such as feed intake, egg production, egg quality, and immune response were measured. The results indicated that dietary supplementation of vitamin C and vitamin E had a positive impact on the performance of laying hens in the humid tropics. Hens receiving the combined vitamin C and vitamin E supplementation showed the highest egg production and feed efficiency compared to the other groups. Additionally, egg quality parameters such as shell thickness and yolk color were improved in the supplemented groups. Furthermore, the immune response of the hens was enhanced by the dietary supplementation of vitamin C and vitamin E, as indicated by higher antibody titers against common poultry diseases. This is particularly important in the humid tropics where disease prevalence is high due to favorable environmental conditions. Overall, the findings of this study suggest that dietary supplementation of vitamin C and vitamin E can improve the performance of laying hens in the humid tropics by enhancing egg production, feed efficiency, egg quality, and immune response. These results have practical implications for poultry producers in tropical regions, highlighting the importance of nutritional interventions to mitigate the challenges posed by the environment. In conclusion, incorporating vitamin C and vitamin E into the diets of laying hens in the humid tropics can be an effective strategy to optimize their performance and health. Further research is recommended to explore optimal dosage levels and potential interactions with other dietary components to fully harness the benefits of these vitamins in poultry production in tropical regions.

Project Overview

This study which lasted for 52 weeks investigated the effects of dietary Vitamin C (Lascorbicacid) and Vitamin E (dl- alpha tocopheryl acetate) on the performance of layinghens in the humid tropics. A total of 240 twenty-four week old Golden Neslink pullets wererandomly selected from a flock of 550 birds and randomly divided into sixteen treatments of15 pullets. The birds were initially vent examined to ensure that they were at point of laybefore commencing the study. Each pullet was randomly assigned to a previously cleanedand 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 combinedwith four dietary levels of Vitamin E: 0, 125, 250 and 375mg Kg-1 basal diet in a 4 x 4factorial arrangement in a Completely Randomized Design. All management principles wereobserved. Dead birds were promptly removed for autopsy when the need arose. At the end ofthe study, three birds were selected per treatment for haematological investigation. Bloodsamples were collected from the wing vein of the birds using a 3ml syringe and a 23-gaugeneedle and placed in micro tubes with Ethlene diamine tetra acetic acid (EDTA) as anticoagulantfor determining the haematological values. The samples were cooled to 4 oC, usingicepacks and transferred to the laboratory within 12h of blood collection. The economicimplication of the study was then calculated. Data obtained were subjected to analysis ofvariance (ANOVA) using SPSS. The mean minimum and maximum indoor temperaturesrecorded during the study ranged between 18.3-25.0 oC and 27. 15-34 oC respectively whilethe RH values lay between 53.0 and 88.9%. These were well outside the zone of thermoneutrality for laying hens. Results obtained indicated that, there were highly statisticaldifferences (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 vitaminE Kg-1 basal diet) was superior to all the other treatments and had the highest values forHDP (85.45±1.15), FI (113.15±0.56), HUS (96.27±0.47), and EWT (69.11±1.52). Thesevalues were however, statistically similar (P > 0.05) to T8 (600mg Vitamin C + 125 mgVitamin 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 betweenVitamin C and E is different from the sum of the two vitamins applied separately. Loss inbody weight, incidence of cracked eggs and mortality were statistically higher (P < 0.01) inT1 (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) weresuperior 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 thehighest values for RBC (4.11±0.15×106), 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 <0.01) from the rest of the treatments. There was highly significant interaction (P < 0.01) in

the net income/dozen of eggs that accrued from the study.

T7 had the highest netincome/dozen egg of N1, 627.11±28.68 while the least net income (N560.50±32.12) wasgenerated from T1. This work therefore upholds that vitamins C and E act in synergy, andthat the combined effects of the two antioxidants are additive, immunomodulatory, antiparasitic

and economical.