Divergent selection for delayed‐type wattle reaction of domestic fowls to BCG antigen

Abstract

1. Two-way selection for delayed-type hypersensitivity wattle reaction (DWR) competence to BCG antigen was carried out over 4 generations, using a flock of White Leghorn chickens. DWR was measured by intradermal injection of BCG into the wattle of chickens. 2. Selection for DWR was effective. The generation means of average selection differential, selection response and realized heritability were 1.15 mm, 0.77 mm and 0.70 respectively. Correlated responses were found in body weight, egg weight and hatchability. In all of these traits, the L line (selected for low wattle reaction) showed higher values than the H line (high reaction). 3. Specific trends in gene frequencies were observed at the major histocompatibility B and alkaline phosphatase Akp loci. 4. Significant line differences were found in graft-versus-host reaction competence and Marek's disease resistance. In both characters, the L line was higher than the H line. No line differences were found in phytohaemagglutinin response, phagocytic activity or immune responses.

Utilizing stochastic genetic epidemiological models to quantify the impact of selection for resistance to infectious diseases in domestic livestock.

“…For example, estimates of heritabilities for traits involved in disease resistance generally range from 0.1 to 0.4 (Sacco et al, 1994;Morris, 1998), similar to heritabilities for production traits. Selection experiments have shown that it is possible to exploit these genetic differences in resistance (Afraz et al, 1994;Mallard et al, 1998;Morris, 1998 2057 no epidemic, a minor epidemic (one that dies out without intervention), and a major epidemic were 0.55, 0.20, and 0.25, respectively. Selection for resistance, under both genetic models, resulted in a nonlinear decline in the probability of a major epidemic and a decrease in the severity of the epidemic, should it occur, until R 0 was less than 1.0, at which point the probability of a major epidemic was zero.…”

Characterization of two Egyptian native chicken breeds using genetic and immunological parameters

“…Also, T-cell mediated immune response of chicken has significant variation among birds of different genetic lineage (Lamont and Smyth, 1984;Cheng and Lamont, 1988). Successful divergent selection of chickens for various T-cell functions suggests that many of these functions are highly heritable, and are often negatively correlated with body weight (Yamamoto and Okada, 1990;Afraz et al, 1994). 05 24 h = toe-web swelling at 24 hr post PHA-P injection.…”

Selective breeding on natural antibodies in chickens

“…Literature generally reports significant lower body weights with selection for increased SpAb (against several antigens) immunity, although it has to be realized that such effects dependent on the number of generations, and the selection criterion (immune trait, and age), and might have different effects (e.g. Afraz et al (1994); Parmentier et al (1998);Boa-Amponsem et al (1999); Yunis et al (2002); Zhao et al (2012); but see Van der Most et al (2011) for an overview). These selection experiments also focused on the immune responsiveness of individuals, in contrast to NAb selection.…”