Evaluation of the efficacy of a novel phytase in short-term digestibility and long-term egg production studies with laying hens.

Three independent trials were conducted to evaluate the efficacy of a novel phytase in laying hens. Trial 1 used a total of 90 laying hens (Lohmann Brown, 33-wk-old) fed either a negative control (NC) diet with 0.09% non-phytate P (NPP) or NC supplemented with 187.5 or 375 FYT phytase/kg feed for 4 d before collection of excreta and ileal digesta to measure ileal digestibility and retention of Ca and P. In trial 2 and 3, a total of 108 laying hens (Hy Line Brown, 25-wk-old) and 360 hens (Lohman Brown, 25-wk-old) were used, respectively. In both trials, the hens were randomly assigned to 3 dietary treatments: NC with 0.1% NPP, positive control (PC) and NC plus 187.5 FYT phytase/kg feed, the experimental diets were fed for 12 wk, and egg production and bone mineralization were measured. The results showed that the ileal digestibility of P increased both linearly (P = 0.012) and quadratically (P = 0.01) with increasing supplementation of phytase in trial 1. In trial 2, phytase supplementation significantly improved egg production, egg weight, and feed conversion ratio and reduced the percentage of broken eggs during the overall trial duration compared with NC. In trial 3, phytase significantly improved egg production, egg weight, and feed intake and reduced the percentage of broken eggs during the entire trial duration. In addition, percentage and weight of bone Ca and P increased significantly with added phytase. In trial 2 and 3, there was no significant difference between PC and the phytase treatment. In conclusion, the novel phytase significantly increased the ileal digestibility of P in a short-term digestibility study and improved egg production and bone mineralization in a 12-wk laying cycle. Ileal digestibility of P rather than P retention in short-term digestibility studies as well as egg production and whole tibia mineralization in long-term studies should be measured to demonstrate the efficacy of phytase in laying hens.

Adaptation of wheat and protein-mineral concentrate intakes by individual hens fed ad libitum in sequential or in loose-mix systems.

1. Feed intake and performance of birds given sequential or loose-mix feeding was investigated from 19 to 42 weeks of age. A complete diet was fed as control (C). A balancer diet (50) was fed either sequentially (S50) or in a loose-mix (L50) with wheat. This diet was formulated to provide a similar nutritive value as C assuming a 50 : 50 diet and wheat intake. Another balancer diet (25) was fed sequentially (S25) or in a loose-mix (L25) with wheat. The diet was to provide a similar nutritive value as C assuming 75 : 25 diet and wheat intakes. In sequential feeding, only wheat was fed in the morning (4 h after lights-on) and the balancer diet in the late afternoon (4 h before lights-off). In the loose-mix treatment, a mixture of the two diets was fed throughout the 16-h daily light. Each treatment was given ad libitum to 25 birds in individual cages. 2. Birds fed on L25 had lower total feed intakes than those receiving C, S50 or S25. Protein intake was reduced with L25 compared to C, S50, S25 and L50. Metabolisable energy (ME) intake was, however, similar among all treatments. Egg production and weight were reduced with L25 compared to S50 and S25. Body weight (BW) was lowered with L25. However, there was high individual variation in all variables. 3. Feeding system (sequential vs loose-mix) had no effect on ME intake. However, the loose-mix treatment reduced feed and protein intake due to lower balancer diet intake. It also resulted in low egg production, egg and BWs compared to sequential feeding. The weights of pancreas and gizzard were heavier with sequential and loose-mix compared to the control. 4. The loose-mix treatment reduced egg-laying performance. Sequential feeding resulted in similar egg-laying performance to conventional feeding and thus could be used to advantage in situations where it is applicable.