Feeding of layers of different genotypes in an organic feed environment

Prohibition on use of synthetic amino acids, GMO or products derived there from, and limited access to approved raw materials restrict possibilities to compose a nutritionally balanced diet in organic egg production. Differences exist between genotypes of birds to resist feather pecking and cannibalism. An experimental genotype (SH), selected for egg production for over 25 generations on low protein diet, was tested against two common commercial hybrids; LSL (Expt. 1) and Hyline (Expt. 2). The birds were fed a control or organic diets, with different sources of protein. LSL and Hyline had a higher production (20-76/80 weeks) than SH, but production deteriorated more severely in the former genotypes when fed the low protein/methionin diet (2 g methionine/kg). Plumage condition was better in SH, compared to LSL. In Expt. 2, feathering was almost complete throughout the whole cycle. However, all genotypes were inferior when fed the low protein diet. SH used the outdoor runs more than LSL, as well as the groups fed the low protein diets, probably due to an increased feed scavenging. On the contrary, Hyline used the outdoor-area twice as much as SH. The experiments showed differences between genotypes but all performed better on a diet with a high protein quality. Consequently, it is difficult to fulfil KRAV ́s standards of 100% organic feed stuffs, without supplements with synthetic methionine or fish meal. Introduction Prohibition on use of synthetic amino acids, GMO or products derived there from, and limited access to approved raw materials restrict possibilities to compose a nutritionally balanced diet in organic egg production. The main challenge for poultry nutritionists is to fulfil the protein requirement, especially regarding the amino acid methionine. Shortage of methionine is known to reduce production in singel hen cages (Schutte et al, 1994). In floor systems a methionine deficiency may also cause severe welfare problems such as feather pecking and cannibalism (Tiller, 2001). It is known that differences exist between genotypes of birds to resist feather pecking and cannibalism (Hughes and Duncan, 1972; Odén et al., 2002; Wahlström et al., 1998). In many countries beak trimming is practised to prevent feather pecking and cannibalism, but this is not allowed in Sweden, Finland and Norway. The aim of the present study was to study effects of a low dietary protein supply on performance of three different layer genotypes. Two common commercial hybrids, Lohmann Selected Leghorn LSL (Expt.1) and Hyline (Expt. 2), were tested against an experimental genotype, SLU-1329 (SH, “Swedish Hen”), selected for egg production for over 25 generations on a low protein diet (13,5 % cp, 0,23 % met, 0,59% lys). The SH is a cross-bred of Rhode Island Red and White Leghorn experimental strains, founded in the 70 ́s. The selection procedures and formation of the experimental strains were described by Liljedahl & Weyde (1980).