Productive performance of laying hens fed wheat-based diets included olive pulp with or without a commercial enzyme product
Olive pulp (OP) is the remainder of olive cake (the raw material resulting from extraction of olive oil) after the removal of the seed fractions. It can be achieved by sieving the dry olive cake to separate most of the seeds. To assess effects of dietary inclusion of OP supplementing with a cocktail commercial enzyme on performance of laying hens and egg quality characteristics, one hundred and twenty 80- week-old Lohmann LSL-Lite hens, with an average laying rate of 80.3 ± 3.8% (late production phase) and 1450 ± 14 g live body weight, were divided in 20 cages (n = 6). Hens in 5 cages (replicates) were randomly assigned to feed on one of the 4 experimental diets. Based on a 2×2 factorial arrangement, 4 iso-caloric and iso-nitrogenous diets (ME =2720 kcal/kg and CP=150 g/kg) including OP (0.0 and 90.0 g/kg) and a commercial cocktail enzyme with mostly xylanase activity (Nutrase®, 0.0 or 0.9 g/kg) were formulated. To determine blood biochemical parameters and differentiable count of white blood cells, one hen per replicate was bled via wing vein on day 35 of trial. To determine egg quality parameters, all eggs during three frequent days were collected on week 4 of trial. Collected data of feed intake (FI), egg production (EP), egg mass (EM) and calculated feed conversion ratio (FCR), blood biochemical parameters and egg quality traits during 6 week trial period was analyzed based on completely randomized design. Hens fed the OP-included diet shown decreased EP compared with hens fed the control diet during week 3 of experimental period (p ≤ 0.05). There was no significant difference between hens fed the OP-included diet and the control diet in terms of FI and EM. In addition, the same trend was observed in terms of enzyme effect on FI and EM. Dietary enzyme supplementation improved FCR compared with hens fed the control diet during week 6 of the experimental period (p ≤ 0.05). Including OP in the diets of hens decreased the blood level of triglycerides (p ≤ 0.05). Including OP in the diets of hens increased the yolk index (p ≤ 0.05). From the results of this investigation, it can be concluded that including OP in diets of laying hens up to 9% would not have deleterious effects on bird's productive performance. In addition, dietary supplementation with a cocktail enzyme with mainly xylanase activity improved FCR in hens.
Key words: Olive pulp, enzyme, laying hens, performance, egg quality characteristics, blood parameters.