Short- and long-distance transport: health, survival and growth of preweaned dairy and dairy-beef cross calves.

The objective of this retrospective, observational study, was to assess the association of transport duration (0.5, 8, 17, or 24 h) with calf survival, diseases (diarrhea and pneumonia), and preweaning average daily gain (ADG). A total of 392,064 calves (dairy females = 125,901 transported 0.5 or 24 h and dairy-beef [DB] cross = 266,111 transported 8 or 17 h) born from Holstein-Jersey (HxJ) dams at 15 farms under the same overall management were included (from January 2022 through March 2024). Calves (female = 146,163 and male = 125,953) were transported following the conditioning protocol in 2,973 loads with a mean age 3.2 d to two separate calf raising-facilities. Dystocic births, failure of passive transfer (FPT) of immunity, calf birth and weaning weights, birth season, calf sex, calf breed, and birth year were recorded. Calf diarrhea and pneumonia, mortality upon arrival at calf raising-facility and up to weaning (60 ± 3 d), and ADG from birth to weaning were recorded. Data were analyzed using GLIMMIX, MIXED, PHREG, or PROC LOGISTIC procedures of SAS. Dam parity, calf health, calf birth season and year, FPT, dystocia, calf sex, calf breed and calf age at transportation were associated with calf mortality up to weaning (P < 0.05). Overall, calf mortality upon arrival at the calf-raising facility was 0.015%, and it did not differ statistically by transport duration. Calves fed two colostrum meals had less FPT compared to one meal (P < 0.0001), regardless of sex or breed. Overall, calf mortality at weaning was 2.49% but varied by transport duration with 3.56% (0.5 h), 1.01% (8 h), 2.18% (17 h), and 1.55% (24 h; P < 0.0001). Calf mortality at weaning differed (P < 0.0001) by transport duration, mostly due to FPT, calf diseases (pneumonia and diarrhea), female dairy calves born to first-calf heifers, sex within DB, birth season, birth year, calf-raising facility and gestation length. Dairy calves transported 24 h (0.76 ± 0.01 kg/d) had higher ADG compared to those dairy calves transported 0.5 h (0.65 ± 0.02 kg/d; P < 0.0001); primarily due to the confounding effect of parity. ADG did not differ for DB calves transported 8 h (0.86 ± 0.04 kg/d) or 17 h (0.82 ± 0.02 kg/d), regardless of parity. While a causal relationship between transport duration and survival or ADG cannot be established, these findings show that key health-related factors early in life play a much larger role in calf mortality at weaning than transport duration.