Abstract:
Physiological and hormonal responses of laying hens fed diets supplemented with two copper sources (CuO and CuSO4) at 0, 100, 200 and 300mg/kg inclusion levels for 12 weeks were investigated. Two hundred and twenty four Nera black laying hens of 15 weeks old randomly arranged in a 2 by 3 factorial in a completely randomized design were used. Twenty eight (28) hens were assigned to each treatment replicated seven (7) times with four (4) hens per replicate. Parameters such as initial and final body weights, daily and total weight gains, daily and total feed intakes, hen day production (HDP) and feed conversion ratio were evaluated. Organs (lungs, heart, spleen, pancreas and kidneys) weights were also determined. Levels in reproductive hormonal changes (estradiol, follicle stimulating hormone, luteinizing hormone, progesterone and testosterone) and blood viscosity were determined likewise the egg and excreta cholesterol levels, and haematological and biochemical indices. The feed intake and HDP generally decreased insignificantly (P>0.05) with increase in copper concentrations. The organ weights and reproductive hormonal changes were insignificantly (P>0.05) affected by increasing concentrations of the two copper sources. The two copper sources had increasing significant (P<0.05) effects on the blood viscosity whereas decreasing and increasing significant (P<0.05) effects were observed for the egg and excreta cholesterol respectively. The red blood cell count generally decreased significantly (P<0.05) as the concentrations of the two sources of copper increased. Uric acid, glucose and cholesterol generally decreased significantly (P<0.05) as the concentrations of the two copper sources increased. CuO-supplemented diets reduced feed consumption in laying hens with better hen day production (HDP) and enhanced blood circulation better than CuSO4. However, CuSO4-supplemented diets reduced egg cholesterol better than CuO in laying hens.
