Onderwerp scriptie

Improving the phosphorus efficiency at the animal and farm level in the Dutch laying hen sector - William Lambert

Reducing phosphorus (P) in laying hen feed is of interest to mitigate the environmental impact of livestock production and to reduce the feed costs. In addition, there is a gap in the P calculations between the P exported per year per farm calculated by the Ministry and the real P analyzed in the manure leading to overestimation of the costs for farmers. Solutions to reduce this P gap need to be elucidated.

Reducing phosphorus (P) in laying hen feed is of interest to mitigate the environmental impact of livestock production and to reduce the feed costs. Modern laying hens have better performance, longer persistency and are now housed in non-cage housing systems. They might therefore be able to support lower dietary P levels. In addition, there is a gap in the P calculations between the P exported per year per farm calculated by the Ministry and the real P analyzed in the manure leading to overestimation of the costs for farmers. Solutions to reduce this P gap need to be elucidated.

Questionnaires were sent to 250 Dutch laying hen farmers to investigate the effect of farm strategies on P efficiency and on the P gap. Two trials were conducted at Schothorst Feed Research with a 2 breeds (Dekalb and LSL) x 6 dietary P levels design. Production performance and P content in eggs and carcasses were measured and P efficiency and P excretion were calculated over 5 periods of time (from 36 to 90 weeks of age). The response rate to the farmer survey was 2.3 % which is not enough to draw reliable conclusions from this material.

The lowest dietary P level could sustain good production performance, significantly increase the P efficiency, decrease the P excretion and numerically lower the feed costs. LSL laying hens had significantly lower FCR, higher P efficiency and lower P excretion and feed costs. Keeping hens until 90 weeks of age instead of 75 weeks of age does not seem to affect the P efficiency and the P excretion at the lowest dietary P level. P content in egg was found to be 1.95 g P/kg egg. P in carcass was found to be correlated to age and recommendations are 5.4 g P/kg from 18 to 75 and 5.6 g P/kg from 75 to 100 weeks of age. When using the new reference values, P excretion is reduced by 3.3 %. Reducing P in diet and choosing for the most efficient breed can improve the environmental and economical sustainability of laying hen farms. Using the new Dutch reference values for P in egg and P in carcass can help to close the gap in the P calculations.


Student: WPM Lambert

Supervisor: T Viets

36 Ects