Pilot studies in organic broiler production – management and cross-breeds

Summary

Two pilot studies were conducted in 1999 and 2000, dealing with management strategies (study A) and alternative cross breeds (study B) in organic broiler production.
Study A: Pastured broilers
280 male chickens were raised in four groups in movable pens on pasture. The pens (3.30 (width) x 4.00 (length) x 0.60 (hight) m) were moved to fresh ground daily. Three groups were conventional broiler-strain chickens (“Ross208”) with 50, 70 and 90 birds per group, and one group was a Swedish heavy layer cross breed (“Derco”) with 70 birds. The birds had ad libitum (free) access to a proprietary concentrate (11.8 MJ ME/kg, 19 % crude protein) all the time and were offered whole wheat, free choice, from day 42 onwards.
The production performance of the Ross chickens showed that high performance is possible in the movable pen system. With the feed given, the modern hybrid used in the experiment grew too fast to be recommended for a 12 weeks growth period: The birds became rather large and showed typical health problems related with rapid growth. Between 50 and 90 birds per pen (corresponding max. 16 to 26 kg liveweight per squaremetre), stocking rate did not seem to influence the birds'performance.
The production performance of the Derco chickens did not reach the standards for slow growing table birds, as they are set by French hybrids today. The actual moving of the pens requires simple but adjusted mechanical aid and routine to keep the physical work input acceptable. Direct measurement of the broilers’ effect on the sward would require relatively more detailed investigation. Monitoring of long-term effects would require long term experiments.
Study B: Screening crosses
Derco hens were crossed with Faverolle, Orpington, Modern Game and Indian Game cocks, and four batches with a total of ca. 130 birds were raised to ages between 12 and 15 weeks. At slaughter day, live and carcass weight were recorded and for three batches, the carcasses were judged, giving scores for the ocular impression of the quantity of meat on breast and legs and feather residues after plucking.
It is concluded that crosses between Derco hens and cocks from breeds like Modern Game, Faverolle and Orpington does not produce considerably more meat than pure Derco chickens. Crosses with Indian Game cocks gave the impression of higher meat yields and a preferable configuration of muscles, but the fertilization rate between Indian Game cocks and Derco hens was relatively low.