Litter composition and ammonia emission in aviary houses for laying hens: Part III, water flow to the litter through fresh droppings

An observational study was carried out to investigate the level and variati on of water input through fresh droppings to the litter in a tiered wire fl oor aviary housing system from 17 to 30 weeks of age of the hens. The mass balances of droppings tall excreta), manure on the belts and litter on the floor were modelled and these equations were used together with measurement s of concentrations and newly developed measuring methods of flows and quan tities of droppings, belt manure and litter. From the differences in the co ncentration of ash, nitrogen, phosphorus and potassium between droppings, b elt manure and litter, it was concluded that the transport of litter betwee n the feathers of the hens to the belts was negligible. The relative amount of excreta deposited in the litter by the hens yielded a peak of about 50% around 22 weeks of age. Thereafter, the flow of droppings to the litter de creased to a stabilized level of about 10%. The flow of water to the litter through the droppings showed the same pattern, with a peak of about 45 g/d per hen and a stabilized level of about 7 g/d per hen. The actual peak mig ht have been 10-30 g/d per hen higher, because measured water concentration s of the droppings were 40-90 g/kg lower than the water concentration of fr eshly excreted droppings. It was hypothesized that the peak in the water fl ow to the litter was caused by the changing behaviour of the hens, as indic ated by the relative number of measured weights of the hens on scales in th e litter area and on a feeding tier. Hens spent less time in the litter are a for scratching and dust bathing after 20 weeks of age, presumably because they spent more time in the nests for laying eggs and on the tiers for eat ing and drinking. (C) 1999 Silose Research Institute.