Effect of enzyme supplementation on performance of pullet chicks fed different level of dietary fibre

Thesis Abstract

A study was conducted to evaluate the performance of pullet chicks fed diets containing varying levels of fibre and supplementary enzyme. One hundred and twenty 3 -week old Harco black pullet chicks averaging 249.87 – 250.23g body weight were randomly divided into 8 groups of 15 birds each. The groups were randomly assigned to 8 energetic (11.78-11.96 MJ/Kg ME) and nitrogenous (20% crude protein) diets in a 4 x 2 factorial arrangement involving four levels (5.0, 6.0, 7.0 and 8.0%) of fibre and two enzyme levels (0 and 0.25%). Each treatment was replicated 3 times with 5 birds per replicate. Feed and water were supplied ad libitum to the birds during the 8 weeks experimental period. Results showed that the weight gain of chicks that consumed diets without enzyme supplementation decreased significantly (P<0.01) as the dietary fibre level increased beyond 6% level . Average daily feed intake (ADFI) also increased significantly (P<0.01) at the 7 and 8% dietary fibre levels. Chicks fed 6% crude fibre diet with enzyme supplementation had significantly (P<0.01) higher average daily weight gain (ADWG), final body weight (FBW) and protein efficiency ratio (PER) and lower (P<0.01) cost of feed per kg weight gain than those fed the control diet. There was a significant (P<0.01) increase in the intake of crude fibre (CF) and nitrogen-free extract (NFE) as the fibre level in the diet increased beyond 6%. Dry matter (DM), nitrogen and CF retentions were significantly (P<0.01) decreased as the dietary fibre increased beyond 6% inclusion level. Increasing levels of crude fibre in the diets had no significant (P>0.01) effect on the WBC and MCHC but affected the rPCV, Hb, RBC, MCH and MCV significantly (P<0.01). There were significant (P<0.01) interactions between dietary fibre and enzyme levels on ADWG, FBW, ADFI, FCR, PER , cost of total feed intake and feed cost per kg weight gain. Enzyme supplementation increased (P<0.01) ADWG, FBW and PER at the 6, 7 and 8% fibre inclusion levels; reduced (P<0.01) feed intake at the 5, 7 and 8% fibre inclusion levels ; reduced (P<0.01) FCR values at all the fibre inclusion levels and reduced (P<0.01) the cost of total feed intake and feed cost per kg weight gain at all the fibre inclusion levels. There were also significant (P<0.01) interactions between fibre and enzyme levels on NFE intake, DM , nitrogen, CF, EE, NFE, PCV, Hb, RBC, MCH and MCV. Enzyme supplementation reduced (P<0.01) NFE intake at the 7% fibre inclusion level; increased(P<0.01) the retention of DM at the 5% and 7 %, fibre inclusion levels; increased (P<0.01) nitrogen retention at the 5%, 6% and8% fibre inclusion levels; increased (P<0.01) CF retention at the 6%,7% and 8% fibre inclusion levels and   increased(P<0.01) EE and NFE retentions at the 7% and 8% fibre inclusion levels; increased (P<0.01) PCV, Hb and RBC at the 6% and 7 %, fibre inclusion levels and   increased (P<0.01) MCH and MCV at the 7% fibre inclusion level. Based on the results obtained in the present study, it was concluded that pullet chicks can be fed 6% crude fibre diet without supplementary enzyme and that up to 8% dietary fibre can be included in enzyme- supplemented pullet chicks’ diet without adverse effects on growth performance of chicks.