Ammonia emission and nutrient load in outdoor runs of laying hens

Abstract

Ammonia emission and nutrient load in outdoor runs oflaying hens were measured at a commercial farm with an outdoor run for 3000 hens, and at an experimental farm with two outdoor runs, each for approximately 250 hens. Ammonia emission was recorded at 5, ro, 15 and 20 m from the hen house, using the ventilated chamber technique. Nutrient load was determined by analysing the fresh droppings.The results show ammonia emission to decrease with increasing distance from the hen house. The average emission per hen was 2.0 mg h-I for the run of the commercial farm, and 0.95 and 0.86 mg h-I for the two runs of the experimental farm. The nutrient load within 20 m from the hen house exceeded the threshold value for nutrient supply from manure (170 kg Nand 44 kg P per hal by a factor 15 on both the commercial farm and the experimental farm. The results show that the ammonia emission from the outdoor run oflaying hens was relatively small compared with the emission from the hen house and that the nutrient load in the outdoor run near the house by far exceeded maximum acceptable levels.

Effects of panels and perches on the behaviour of commercial slow-growing free-range meat chickens

“…A deficiency of areas where the birds can feel safe often results in a high reluctance of the birds to move away from the chicken house (Grigor and Hughes, 1993;Dawkins et al, 2003) where they can shelter in case of any perceived danger. This uneven use of indoor and outdoor space leads to a difference in the effective density of birds throughout the space which may lead to some problems such as increased disturbances in the wall area (Cornetto et al, 2002), overuse and erosion of the outdoor areas closer to the house (Breitsameter et al, 2014), or an excess of nutrients in such areas (Aarnink et al, 2006).…”

Total loss and distribution of nitrogen and phosphorus in the outdoor run of organic laying hens

“…Mean load of N and P in a zone was the mean of the N and P load at all possible distances from the winter garden in a specific zone on a specific farm. To compare the load we measured with that measured by Aarnink et al (2006), we converted daily load (kg ha À1 d À1 ) to yearly load by multiplying by 335, thereby including a zero occupancy period of 30 d between cycles (during these days the animal house was cleaned and during the first weeks of a production round hens had no access to the run) Total mass of N and P (kg d À1 ) excreted outside was calculated for each zone as well as for the entire outdoor run of each farm. Total mass of N and P excreted into a zone was calculated by multiplying the mean load of N and P in a zone with the area of the zone.…”

“…In a natural ecosystem, the level of N and P in the soil is more or less balanced, because animals remove N and P by feeding on the vegetation and return most of this N and P in faeces and urine. In organic hen husbandry, however, excretion of N and P in the outdoor run generally far exceeds the uptake by vegetation (Aarnink et al, 2006). Especially in organic farming reduction of loss of N and P from the production cycle is important, because the use of artificial fertilisers is prohibited (EC, 1991).…”

“…Vegetation growth, especially in parts of the outdoor run with a high hen density, is very limited in practice, because vegetation is destroyed by intensive foraging (Bubier and Bradshaw, 1998). Aarnink et al (2006) showed that locally high loads of N and P (i.e. mass of N and P excreted per m 2 in the outdoor run) may occur, because hens tend to stay close to the hen house (Zeltner and Hirt, 2003;Hegelund et al, 2005).…”

“…Total mass and load of N and P excreted into the outdoor run should be measured year round on several commercial farms for several flocks to obtain a realistic estimation under commercial circumstances, because of dependency on factors such as: diet (Elwinger et al, 2008); flock size (Hegelund et al, 2005); age (Mirabito and Lubac, 2001;Hegelund et al, 2005); genotype (Elwinger et al, 2008); rearing management (Grigor et al, 1995;Mirabito and Lubac, 2001;Bestman and Wagenaar, 2003); weather and climate (Hegelund et al, 2005;Elwinger et al, 2008); time period per day the outdoor run is accessible (Aarnink et al, 2006) and diurnal rhythm of the hens (Bubier and Bradshaw, 1998;Hegelund et al, 2005;Zeltner and Hirt, 2008); layout of the outdoor run and presence of natural or artificial objects (Zeltner and Hirt, 2003;Harlander-Matauschek et al, 2006). Although some of such factors have been quantified in specific situations, a year round indirect determination of total mass and load of N and P excreted into the outdoor run on several commercial flocks and farms has not been carried out.…”