Response of laying hens to diet inclusion of canola meal as influenced by dietary nonphytate phosphorus level and microbial phytase supplementation

An experiment employing a factorial arrangement of three levels (0, 8 and 16%) of canola meal (CM), two levels (0.15 and 0.25%) of nonphytate phosphorus (NPP), and two levels (0 and 450 unit/kg; as fed basis) of microbial phytase was conducted using 216 Hy-Line W36 laying hens from 39 to 47 weeks of age. The birds receiving CM consumed more (P < 0.05) feed than birds receiving corn-soybean meal (SBM) diets. During the second 4 weeks of the experiment (44 to 47th weeks of age), egg production and egg mass were lower (P < 0.05) for birds receiving corn-SBM diet containing reduced NPP level; however, the adverse effects of reduced NPP were overcome by phytase supplementation (P < 0.05). During the second 4-week (44 to 47th weeks of age) and over the whole experiment (39 to 47th weeks of age), production of abnormal eggs was increased (P < 0.05) by feeding reduced NPP level; phytase supplementation decreased (P < 0.05) egg abnormality only when added to this diet. At the first egg sampling (43rd week of age), egg shape index and eggshell thickness were increased (P < 0.05) by phytase supplementation. Reduced NPP level caused a lower eggshell thickness in hens fed corn-SBM diet (P < 0.05). At the second egg sampling (47th week of age), birds fed corn-SBM diets or reduced NPP level produced eggs with lower (P < 0.05) shell thickness, whereas dietary phytase supplementation reversed these adverse effects (P < 0.05). Reduced NPP level increased serum thyroxine concentration in birds fed corn-SBM-CM diets (P < 0.05). The results showed that CM can be included in laying hen diets up to 16% during 39 to 47 weeks of age without any adverse effect on their health and productivity. Moreover, the results indicated that reduction of NPP level in corn-SBM-CM diets had little effect on performance and eggshell quality. The adverse effects of lowering NPP level in corn-SBM diets could be substantially reduced by phytase supplementation.

Response of laying hens to diet inclusion of canola meal as influenced by dietary nonphytate phosphorus level and microbial phytase supplementation Keywords:

bone ash , canola meal , eggshell quality , performance , phosphorus , phytase