Two experiments (E1, E2) were conducted to compare the influence of sires (sire A on dam C versus sire B on dam C) and straight-run versus sex-separate rearing on the incidence of bacterial chondronecrosis with osteomyelitis (BCO) in broilers, explain first-named author, R.F. Wideman Jr. of the University of Arkansas and co-authors there and with Cobb-Vantress Inc.

In a paper in Poultry Science, they explain that fertile eggs from commercial breeder flocks were incubated and hatched at the University of Arkansas Poultry Research Hatchery.

Male and female chicks were reared together (straight-run) or separately (sex-separate) in pens measuring three metres by three metres on litter or flat wire flooring with 65 (E1) or 60 (E2) birds per pen.

Necropsies revealed lesions that are pathognomonic for BCO in at least 98 per cent of the birds that became lame.

The SigmaStat Z-test was used to compare cumulative BCO incidence to eight weeks of age.

For birds reared on litter, the incidence of BCO was low, regardless of cross or sex (range: 1.7 to 5.1 per cent; P≥0.6).

Within a cross and sex, rearing the broilers straight-run versus sex-separate on wire flooring did not significantly affect the incidence of BCO.

Significant incidences of BCO did not develop until after day 40. Males from the sire A cross developed a higher incidence of BCO than males from the sire B cross in E1 (27 versus 17 per cent, respectively; P=0.009) but not in E2 (28.5 versus 22.6 per cent, respectively; P=0.141).

In both experiments, males from the sire A cross developed a higher incidence of BCO than females from the sire B cross (27 versus 11.9 per cent, in E1; 28.5 versus 14.8 per cent, in E2).

With the sexes pooled, broilers from the sire A cross consistently developed a higher incidence of BCO than broilers from the sire B cross (21.4 versus 14.9 per cent, P=0.005 in E1; 26.5 versus 18.7 per cent, P=0.003 in E2).

High susceptibilities to both femoral head (all femoral head necrosis = 66 to 85 per cent incidences) and tibial head (all tibial head necrosis = 81 to 96 per cent incidences) BCO lesions were demonstrated in lame birds from both sexes and crosses.

Wideman and co-authors conclude their results support a sire influence on the susceptibility of broilers to BCO. Sire lines can be chosen to reduce BCO susceptibility when broilers are grown beyond six weeks of of age.

Reference

Wideman R.F. Jr., A. Al-Rubaye, D. Reynolds, D. Yoho, H. Lester, C. Spencer, J.D. Hughes Jr. and
I.Y. Pevzner. 2014. Bacterial chondronecrosis with osteomyelitis in broilers: Influence of sires and straight-run versus sex-separate rearing. Poultry Science. 93(7):1675-1687. doi: 10.3382/ps.2014-03912

July 2014