Table 2.
Serological data on paired samples collected from a selection of individuals in four groups of beef-calves at a bull testing station operating an ‘all in–all out’ management system
| Year | Virus | Number of animals seropositive/number of animals examinedb (mean corrected optical densityc) |
Seroconversionsd (month) | |||
|---|---|---|---|---|---|---|
| Augusta | October | November | January | |||
| 2000/2001 | BRSV | 3/20 (0.6) | – | – | 0/20 | – |
| 15% | 0% | |||||
| PIV-3 | 5/10 (0.5) | – | 10/10 (1.4) | – | August–November | |
| 50% | 100% | |||||
| BCoV | 15/30 (0.8) | – | 6/30 (0.9) | 7/30(0.8) | November–January | |
| 50% | 20% | 23% | ||||
| 2001/2002 | BRSV | 4/10 (0.7) | – | 1/10 (0.5) | 10/10 (1.0) | November–January |
| 40% | 10% | 100% | ||||
| PIV-3 | 2/10 (1.0) | – | 10/10 (0.8) | – | August–November | |
| 20% | 100% | |||||
| BCoV | 6/10 (0.5) | – | 3/10 (0.9) | 10/10 (1.7) | November–January | |
| 60% | 30% | 100% | ||||
| 2002/2003 | BRSV | 9/20 (1.0) | 8/20 (0.6) | 4/20 (0.7) | 4/20 (0.7) | – |
| 45% | 40% | 20% | 20% | |||
| PIV-3 | 4/10 (0.5) | 3/10 (0.7) | 10/10 (0.8) | 10/10 (1.3) | August–October, October–January | |
| 40% | 30% | 100% | 100% | |||
| BCoV | 87/166 (1.0) | 160/166 (1.4) | – | – | August–October | |
| 52% | 96% | |||||
| 2003/2004 | BRSV | 4/20 (0.6) | 20/20 (1.3) | 20/20 (1.9) | 20/20 (1.9) | August–October |
| 20% | 100% | 100% | 100% | |||
| PIV-3 | 11/20 (0.8) | 19/20 (0.9) | 20/20 (1.3) | 20/20 (1.4) | August–October, October–November | |
| 55% | 95% | 100% | 100% | |||
| BCoV | 16/24 (0.8) | – | 7/24 (0.8) | 7/24 (0.8) | – | |
| 67% | 29% | 29% | ||||
BRSV, bovine respiratory syncytial virus; PIV-3, bovine parainfluenza virus 3; BCoV, bovine coronavius.
a
Samples were obtained from calves (4–8 months old) after commingling of calves from 99–124 beef-breeding herds.
b
Sera were diluted 1:25 and analysed in indirect ELISA (SVANOVA Biotech). Corrected optical density (COD) values ⩾ 0.2 were considered positive. Not analysed (–).
c
Mean COD values of positive samples.
d
Seroconversion was defined as a negative COD value converting to a positive in paired sera. No seroconversions detected (–).