Calf birth weight and its association with calf and cow survivability, disease incidence, reproductive performance, and milk production.

The hypothesis was that calf birth weight (CBW) and a cow calf index [CCI; (calf weight/cow height at parturition) x 100] would be associated with calf and cow survivability, disease incidence, reproductive performance, and milk production. Data were collected in a prospective cohort study from one commercial dairy milking 2,800 Holsteins in upstate NY from March 2007 to August 2007. Animals were enrolled at parturition until 1,245 calvings were available for analysis. Data consisted of on-farm measurements of morbidity, mortality, and performance, and data were analyzed using a series of multivariable models including ANOVA and time-to-event analysis. A higher CBW and a higher CCI were associated with greater odds of lameness. Compared with the lowest quartile of CBW, the odds of the dam becoming subsequently lame increased as the CBW quartiles increased from 2 to 4; odds ratio = 1.5, 2.7, 3.6, respectively. Compared with the lowest quartile of CCI, the odds of the dam becoming subsequently lame increased as the CCI quartiles increased from 2 to 4; odds ratio = 4.6, 4.7, 4.8, respectively. Assistance during parturition was associated with higher CBW and with higher CCI. Calves born from assisted parturition had significantly higher CBW (CBW = 43.7 kg) and CCI (CCI = 31.4) compared with calves born from nonassisted parturition (CBW = 41.5 kg and CCI = 29.7). Neither CBW nor the CCI were associated with stillbirth incidence, calf mortality past 12 h of life, cow reproduction, or cow survival. We concluded that CBW, and especially the ratio of CBW to dam size, can be associated with some downstream effects, e.g., obstetrical assistance, lameness events, and milk production.