The aim of the pan-European FreeBirds project has been to develop successful husbandry practices in organic production to ensure chickens spend more time outdoors.
Poultry World reports on some of the conclusions highlighted in a recent webinar on this multifaceted project.
Access to the range is mandatory in organic production, however, not all hens dare to venture out into the open. Photo: Peter Roek
Free-range hens on various outdoor runs should be rotated to reduce accumulation and the risk of nutrient losses, while producers should look to rotate crops with high phosphorus needs.
A study on soil organic matter and nutrient levels
The conclusions follow a study by Valentina Ferrante, senior poultry researcher at the University of Milan, Italy, into soil organic matter and nutrient levels in different organic poultry runs. The study is particularly important given the drive of the European Commission’s Farm to Fork strategy to reduce ammonia emissions, as well as leaching and the runoff of nitrates and phosphorus. In organic hen husbandry, the excretion of nitrogen (N) and phosphorus (P) in the outdoor run generally far exceeds its uptake by vegetation.
Hens stay close to the hen house
Past research has shown that N and P losses from the outdoor run depend on the amount and composition of the manure deposited, its distribution and the nutrient uptake by vegetation. Hens tend to remain close to the henhouse, meaning that an accumulation of droppings takes place. This area is often bare and highly loaded with N and P nutrients, plus the infectious stages of helminths and coccidia.
A forest, a farm and artificial shelter
Dr Ferrante outlined that this research was carried out on 3 farms – farm A (forest environment/heavy soil), farm B (orchard setting/light soil) and farm C (artificial shelter/light soil). Soil samples (24 in all) were taken on each farm at different distances from the house (5, 20 and 50m) and at 1 position out of the range as a test at depths of 0-10cm and 10-30cm. Analysis was carried out to determine dry matter, pH, organic carbon, total Kjeldahl nitrogen, nitrate nitrogen and available phosphorus (Olsen method).
She said that hen droppings contributed to maintaining a soil pH above neutral (7) and up to 7.5 close to the poultry house. Unexpectedly, total nitrogen concentrations showed an increasing trend with distance away from the poultry house, with the highest values in the test areas. The same applied to organic carbon in farm C with sandy soil, where the differences were more pronounced than for N. This is presumed to be due to the hens’ presence which reduces the vegetation cover on the soil and makes it more prone to organic matter loss.
“This is the most critical point in the results...”
She concluded by saying that high values were found for both nitrate nitrogen (>50mg NO3-N/kg) and Olsen phosphorus (maximum values at 500-1000mg P/kg), particularly in areas close to the poultry house and for the most superficial soil level. “This is the most critical point in the results, representing a strong accumulation, especially of phosphorus, and a risk in terms of runoff and leaching of 2 elements that can contribute to surface water (particularly P) or groundwater (particularly N) contamination.”
Choosing the right bird
Being in touch with and caring for the land and environment is essential in organic farming. But choosing the right commercial layer hybrid for organic egg production is equally important for production that is both environmentally and economically sustainable. Webinar spreaker, Anja Brinch Riber, from the Department of Animal Science at Aarhus University in Denmark, looked at the welfare parameters for Bovan Brown birds and Dekalb Whites.
From a major study done by Aarhus University, she concluded that Bovan Browns fared better than or equally as well as Dekalb Whites (see box). The study monitored the 2 commercial layer hybrids for egg production and welfare issues. Dekalb Whites found shelters in the organic ranges to be particularly important and were used frequently.
The research monitored Bovan Brown and Dekalb White layer hybrids (100 birds per pen in 6 pens) between 17 and 38 weeks of age. They were housed in accordance with organic regulations with a stocking density of 5.7 hens/m2, a range area of 4.05 m2 per hen and shade (with 4 greenhouse shade cloths (2×10m) per range).
Birds were checked weekly on the same weekday. At the end of the experimental period the vegetation in each range was checked for type, cover and height. Clinical welfare indicators (comb wounds, body weight, bumble foot, footpad lesions, hyperkeratosis, keel bone fractures and plumage damage) were measured for all 1,200 birds on the day of placement and on the last day of the experiment.
Egg production and other parameters were also examined at weeks 22, 27, 32 and 37 (15-20 eggs per pen were examined for egg weight, shell thickness and shell weight). The proportion of hens on the range during the 21 weeks was also monitored.
Results showed that the Dekalb White layers used the range more in weeks 17-25 and less in weeks 27-32 than the Bovan Brown. Fewer hens used the range in week 38 when the temperature dropped and windspeed increased. Ranging distance from the house was also observed with Dekalb White hens having the longest ranging distance in weeks 17-24 while Bovan Brown took over in weeks 26-38. The change in distance was greater for Bovan Brown (3-48m) compared to Dekalb White hens (14-30m).
A larger proportion of Dekalb White hens used the shelters compared to Bovan Brown hens but, once again, weather conditions significantly affected use. Results related to vegetation cover found that more bare ground was found in Bovan Brown ranges compared to Dekalb White at 55m and 85m. The further away from the pop-holes the more grass cover was found.
Results of Aarhus University welfare study
• Plumage cover: Worsened for both Dekalb White and Bovan Brown. Dekalb White hens had a worse plumage score at both ages.
• Keelbone fractures: Fractures were more likely for Dekalb White hens at 38 weeks than 17 with the prevalence of fractures increasing with age for both hybrids.
• Foot condition: Prevalence of hyperkeratosis increased with age in both hybrids with Bovan Brown birds more likely to have it at 38 weeks. However, footpad lesions were higher in Dekalb White birds and percentage of birds with bumble foot was around 2-3% for both.
• Comb wounds: Dekalb White hens were substantially more likely to suffer wounds (32% compared to 7%) by week 38.
• Body weight: Bovan Brown hens weighed more than Dekalb White hens at 17 weeks and continued to increase the gap by week 38.
• Mortality: Dekalb White hens had a Dekalb White mortality (1.83%) compared to Boan Brown (0.33%). The most common cause of death was ‘egg yolk peritonitis’.
• Floor eggs: The percentage of floor eggs increased with age for both hybrids but rose more for Dekalb White birds.
• Egg and shell weight/thickness: Bovan Brown eggs tended to be heavier and have thicker shells than Dekalb White hens at all ages with thickness levels decreasing with age.