Table 4.
Manuscripts comparing respiratory health across different durations of dam-calf contact1
| Study | Country | Breed | Study design | Groups compared (length of dam- calf contact) | n (calves) | No. of herds (groups) | Conclusion | |
|---|---|---|---|---|---|---|---|---|
| Boonbrahm et al., 2004a | Thailand | HF2 | Incidence of disease compared in calves provided restricted suckling opportunities and those fed by bucket | 3 d free contact (both groups), then 15 min (2×/d) for 80 d (postmilking for restricted suckling group) | 40 | 1 (2) | Incidence of pneumonia 3× higher in bucket reared versus suckling calves2 | + |
| Perez et al., 1990 | The Netherlands | HF, Dutch Friesian, Meuse-Rhine-Issel, and cross breeds | Multi-herd study comparing mortality in dairy calves under different managerial systems (including whether calves were allowed to suckle) | Not specified | 1,037 | 63 | Allowing the calf to suckle was not a risk factor for respiratory disease | = |
| Little et al., 1991 | Ethiopia | Friesian × Boran | Health assessed in calves permitted restricted suckling opportunities compared with calves fed by bucket until weaning at 94 d | 24 h free contact then separated, compared with 24 h free contact then restricted suckling 2×/d before milking | 13 | 1 (2) | No difference in pneumonia incidence between calves obtaining milk by restricted suckling versus bucket | =3 |
| Krohn et al., 1999 | Denmark | HF | Incidence of disease compared in calves separated from the dam, or kept with the dam (with and without suckling opportunities) | Immediate separation or 4 d of contact | 57 | 1 (3) | No difference in the treatment groups with respect to incidence of pneumonia | = |
| Svensson et al., 2003 | Sweden | Swedish Red, HF, cross-breed | Multi-herd study including disease evaluations by farmers and veterinarians and questions on colostrum feeding methods | Not specified | 3,081 | 122 | No difference in odds of pneumonia in calves that received colostrum by suckling compared with other methods | = |
| Lundborg et al., 2005 | Sweden | Swedish Red, HF, cross-breed | Multi-herd study including disease evaluations by farmers and veterinarians and the effect of management factors | Farms categorized based on proportion of calves kept with the dam for some time after birth (0, >0 but <1, or 1 or more d) | 3,081 | 122 | Proportion of calves that were kept with dam not associated with pneumonia risk | = |
| Gulliksen et al., 2009a | Norway | Not specified, likely varied | Multi-herd study to evaluate risk factors for respiratory disease | ≤24 h of contact compared with >24 h of contact | 5,101 | 135 | Leaving calves with the dam for >24 h was found to increase the risk of respiratory disease in calves. Hazard ratio (95% CI) = 3.5 (1.3–9.2) | − |
Listed for each study are country, breed of cattle, study design, groups compared (in reference to length of cow-calf contact), total number of animals sampled, number of herds included (and groups within herds where applicable), and the authors' conclusion and direction of effect (with + signifying a beneficial effect of suckling or cow-calf contact, − signifying a negative effect, and = representing no difference. Studies are ordered by effect direction, then chronologically by year, then alphabetically within year).
HF signifies that breed was reported as Holstein, Friesian, or Holstein-Friesian. This designation includes country-specific variants such as Danish Holstein.
No statistical test performed.