EGG CHARACTERISTICS AND LAYING PERFORMANCE OF HENS FED GRIT-BASED DIETS FROM TWO CASSAVA (Manihot esculenta CRANTZ) VARIETIES SUPPLEMENTED WITH ENZYMES

Abstract

Maize which serves as the main dietary energy source for poultry production is bedevilled with vicious seasonal scarcity. Cassava grits has similar metabolisable energy as maize and could replace dietary maize for laying hens. However, there is dearth of information on the effects of grits from different cassava varieties on egg attributes and performance of hens. Thus, egg characteristics and laying performance of hens fed grit-based diets from two cassava varieties with supplemental enzymes were investigated. Eight weeks old ISA Brown pullets (n=364), weighing 0.57±0.02 kg were randomly allotted to 13 isocaloric and isonitrogenous diets, of equal number of pullets, replicated four times. Maize was replaced with TME 419 cassava grits at 0 (T0¬), 33 (T1), 66 (T3) and 100% (T5) without enzyme and with supplemental carbohydrase-phytase-protease enzyme-cocktail (T2, T4, and T6, respectively). Similarly, maize was replaced with TMS 01/1368 cassava grits at 33, 66 and 100% without enzyme-cocktail (T7, T9 and T11, respectively) and with the supplemental enzyme-cocktail (T8, T10, and T12, respectively), in (2×3 2)+1 augmented factorial arrangement in completely randomised design. The pullets were fed ad libitum till week 18, then from week 19 on corresponding layer diets till week 72. Hen-Day Egg Production-HDEP (%), Yolk Weight-YW (g) and Haugh Unit-HU, were assessed at week 22-38 (Early Laying Phase-ELP), 39-55 (Mid Laying Phase-MLP) and 56-72 (Late Laying Phase-LLP). At week 72, blood (5 mL) was sampled and analysed for Alanine Amino Transferase-ALT (IU/L), Aspartate Amino Transferase-AST (IU/L) and thiocyanate (mg/dL) using standard methods. Data were analysed using descriptive statistics, regression and ANOVA at α0.05. The HDEP of 42.3±1.2 (T0), 42.6±1.8 (T1) and 42.4±1.8 (T2) at ELP; and T2 at MLP (79.9±2.5) and LLP (73.4±3.0) were significantly higher than in other treatments. The YW at ELP in T0 (14.2±0.3), T1 (14.3±0.2) and T2 (14.3±0.3); and at MLP and LLP in T0 (17.8±0.4; 18.9±0.4), T1 (17.7±0.4; 18.9±0.4), T2 (18.1±0.3; 19.1±0.5), T7 (17.7±0.5; 19.1±0.4) and T8 (17.8±0.4; 19.1±0.5), respectively were significantly higher than in other diets. Increased dietary inclusion levels of grits resulted in linear reduction of HU at ELP (R2 = 0.94), MLP (R2 = 0.99) and LLP (R2 = 0.99). The HU of 93.3±1.4 (T0), 93.2±1.8 (T1), 93.0±1.7 (T2), 92.7±1.4 (T7), and 93.4±2.0 (T8) at ELP; 90.6±1.2 (T0), 90.4±1.0 (T1), 90.1±0.9 (T2), 90.0±2.4 (T7), and 89.9±0.9 (T8) at MLP were significantly higher than in other diets. Similarly, HU of 87.3±1.7 (T0), 87.2±1.5 (T1), 86.9±1.7 (T2), 86.8±1.0 (T7), and 86.6±1.2 (T8) at LLP, were significantly higher than in other diets. The ALT of hens on different treatments were similar, indicating no dietary hepatoxicity. However, AST of hens on T0 (65.6±2.8) was significantly lower than in other diets. Thiocyanate of 0.29±0.0 (T0) was significantly lower than 2.07±0.1 (T5), 2.10±0.1 (T6), 2.13±0.1 (T11) and 2.13±0.1 (T12). Replacement of maize with TME 419 grits at 33% despite enzyme supplementation, in the early laying phase, and 66% with enzyme supplementation at the mid and late laying phases, sustained hen laying performance. However, egg quality decreased with the inclusion of cassava grits, despite enzyme supplementation.