ABSTRACT
In consideration of the prolong use of Growth Promoting Antibiotics (GPAs) in animal production and the side effects of their residues in meat and eggs which can be transmitted to humans after consuming these products, attention is being drawn to the use of some medicinal plants readily found in Nigeria which have valuable impacts on the growth, production, health and meat quality without leaving residues in the product or the rearing environment. Plants with most of these properties are Bitter Leaf (Vernonia amygdalina), Scent Leaf (Ocimum Gratissimum), and Clove (syzygium Aromaticum). This study, therefore, was undertaken to evaluate the reproductive performances and physiological responses of commercial laying hens fed diets with bitter leaf, scent leaf, clove and their combinations as phytogenic feed additives.
A total of 360 NovoGen Brown point of lay pullets were used for this study and the experiment was laid out in a completely randomised design. The birds were allotted to eight (8) treatments with three (3) replicates per treatment to give fifteen (15) birds per replicate. Thus, each treatment had Forty Five (45) birds. For this study, treatment 1 was the control. The test ingredients were administered as follows: Treatment 2 (0.5% Bitter leaf), Treatment 3 (0.5% Scent leaf), Treatment 4 (0.5% Clove), Treatment 5 (0.25% Bitter leaf + 0.25% scent leaf), Treatment 6 (0.25% Bitter leaf + 0.25% Clove), Treatment 7 (0.25% Scent leaf + 0.25% Clove), Treatment 8 (0.18% Bitter leaf + 0.16% Scent Leaf + 0.16% Clove).
The phytogenic additives influenced the layers’ performances, at the peak of egg laying, Hen Day Production (HDP) was highest (81.33 and 79.99%) in Treatment 6 and 7, with a significant difference (P<0.05) from the control feed (72.56%). Feed conversion efficiency (feed/dozen eggs) was better enhanced across the administered phytogenic additives (1.51 - 1.76) compared with the control with an efficiency of 2.18. The best feed conversion efficiency 1.51 was obtained from Treatment 6, while the least efficiency of 1.99 and 2.18 were recorded in Treatment 4 and the Control. The assessed egg quality parameters such as egg weight, shell thickness, albumen index, yolk index, Haugh unit and yolk colour were improved among the treated groups. Most of them had significant difference (P<0.05) from the control. Haematological profile of the hens used for this experiment showed no significant difference in red blood cell counts and platelets between treatments. However, for white blood cell count, Treatment 5 had the highest count 143.85x103/µl, though not significantly difference from Treatment1, 3 and 7 that had 123.96x103/µl, 128.75x103/µl, and 126.89x103/µl respectively. The result of the serum biochemistry of the laying hens fed the diets with the phytogenic feed additives showed no significant differences among the assessed parameters in Sodium, Bicarbonate, Urea, Creatinine, Glucose and globulin values. The values of the blood serum enzymes assessed to judge the antioxidant capacity of the laying hens fed the test ingredients showed least level of Alkaline Phosphate (ALP) in the control (193.79 IU/L) and was also notsignificantly different (P>0.05) from the values obtained from Treatment 6 (212.48 IU/L) andTreatment 8 (243.53 IU/L). The serum lipid profile of the birds showed no significant difference in triglycerides, low density lipoprotein (LDL) and very low-densitylipoprotein (VLDL)values.Asobservedinthisstudy,mostofthetestadditiveseffectivelypromotedtheoverallperformance of the laying hens. In conclusion, this study has shown thatBitter leaf, Scent Leaf, Clove and their combinations offerthe poultry industry promising alternatives to antibiotics
