Feeding layers of different genotypes in organic feed environments.

1. Two experiments were carried out to evaluate the suitability of an experimental laying hen genotype (SH) in organic egg production. SH had been selected over 25 generations on a low protein diet (130 g/kg) based on home grown feedstuffs. SH hens were compared with LSL (Experiment 1) and Hyline (Experiment 2) hens. The birds were kept in 12 aviary pens with access to outdoor runs. 2. Four diets, which were different in each experiment, were used. A control diet was compared with diets based on feedstuffs supposed to be able to be grown and produced according to organic standards. The diets differed in the content of sulphur amino acids. 3. There were no significant differences in mortality caused by diets or genotypes but an incidence of cannibalism occurred in one Hyline group fed on the diet with the lowest methionine content. 4. Severe feather pecking of LSL birds occurred and was worst on the low protein diet. In Experiment 2, signs of feather pecking of birds on the low protein diet occurred at the end of the experiment, but there was no difference between the genotypes. There was no significant difference in number of eggs produced between diets. Egg weight was influenced by diets in both experiments and by genotype in Experiment 2. Number of misplaced eggs was higher in SH hens in both experiments. There were few significant diet x genotype interactions. 5. The use of the outdoor area was influenced by diets and genotype in both experiments. 6. In conclusion, diets low in methionine content influenced predominantly plumage condition and egg weight, although production of eggs by number was unaffected. The SH hen adapted well to organic conditions, as did the Hyline genotype.

Systemic immune response of young chickens orally immunized with bovine serum albumin.

The efficacy of oral immunization, with and without commercial adjuvants, to mount a systemic immune response in young chickens was studied. Bovine serum albumin (BSA) mixed with a pegylated C8/C10 mono/di-glyceride, (Softigen), or Cholera toxin B-subunit (CTB), administered orally by gavage to 15-day-old chickens resulted in circulating immunospecific anti-BSA IgG, IgM and IgA antibodies. Continuous 5-day oral administration of BSA without adjuvant also resulted in immunospecific IgM and IgA antibodies in the circulation of chickens first immunized at 15 days of age; and immunospecific antibodies of all three classes in chickens first immunized when they were 22 days old. IgG and IgM serum concentrations were more than 4 to 10 times higher, respectively, in CTB- and Softigen-treated chickens as compared to chickens immunized without adjuvants. The IgA response in the orally immunized chickens seemed unaffected by CTB and Softigen. The antibody concentrations in chickens immunized subcutaneously with BSA emulsified in Freund's Incomplete Adjuvant (FIA) were approximately 10 times higher than those of the chickens orally immunized using CTB and Softigen.

Single-step divergent selection for male comb shape in two White Leghorn lines.

1. Divergent selection for comb shape (SH, the way that the cockerel bears the comb) was performed in 2 White Leghorn lines in a study aimed at assessing possibilities for improving SH. 2. Line A, selected for large comb size (CS) at 29 weeks of age, had great SH problems whereas Line H, selected for high hyaluronic acid concentration in the comb (HA), had minor SH problems. Multivariate analyses were used to estimate genetic parameters for SH, CS and HA in lines A and H and in a control line (C). 3. Significant direct selection responses for SH were achieved in both lines. There were significant unfavourable correlated responses for CS in both lines. 4. The correlated responses for HA were not significant and were unfavourable in Line A and favourable in Line H. 5. Heritabilities for SH and CS were high in both lines and relatively low for HA. Most of the genetic correlations were in agreement with the correlated responses obtained.