Investigating nutritional strategies during a rest period to improve health, growth, and behavioral outcomes of transported surplus dairy calves

Abstract

The objective of this study was to investigate the effects of feeding surplus dairy calves a milk replacer (MR) or one of 2 different oral rehydration solutions (ORS) during a mid-transportation rest period on metabolic and clinical health indicators, growth, and behavioral outcomes after arrival to a calf-raising facility. Surplus dairy calves (n = 128) were transported in 4 cohorts from February to July 2022 for 12 h to a holding facility, rested for 8 h, then transported for an additional 6 h to a calf-raising facility. Upon arrival to the holding facility, calves were randomly assigned to 1 of 3 treatments: MR (n = 43), a high sodium ORS developed for diarrhea (ORS-D; n = 43), or a high potassium ORS developed for transportation (ORS-T; n = 42). The exact age of calves at transportation was unknown, however all calves were under 14 d of age. Calf body weight at enrollment was 43.9 ± 5.9 kg, 43.7 ± 6.5 kg, and 45.0 ± 4.5 kg for calves fed MR, ORS-D, and ORS-T, respectively. Calves were fed 2.0 L of their treatment twice, once upon arrival and once before leaving the holding facility. At unloading and reloading at the holding facility, calves were weighed and blood sampled. Calves were also health scored at unloading at the holding facility. After arrival at the calf-raising facility, calves were weighed, health scored, and blood sampled. Blood samples were collected at 24 and 48 h and body weight (BW) was recorded at 24 h, 48 h, 72 h, 5 d, 7 d, 14 d, and at 8 wks after arrival to the calf-raising facility. Calves were also health scored daily for 14 d, which included fecal consistency scoring and evaluating the presence or absence of respiratory disease. Lying time, lying bouts, and activity index were measured during transportation and from 3 d relative to transportation using accelerometers. At arrival to the calf-raiser, calves fed ORS-D had higher concentrations of NEFA and BHB than calves fed MR. Furthermore, calves fed ORS-T had higher concentrations of BHB at arrival to the calf raiser compared with calves fed MR. In the 14 d after arrival to the calf-raiser, there was evidence that calves fed ORS-T had a higher proportion of days with diarrhea and respiratory disease compared with those fed MR. During transportation, calves fed ORS-T had a lower activity index than calves fed MR, suggesting that ORS-T calves had lower overall activity. Additionally, on the day of transportation (d 0), ORS-T and ORS-D calves had a lower activity index than calves fed MR. There were no treatment effects on growth outcomes. The results of this study suggest that feeding MR rather than an ORS during a mid-transportation rest period could minimize fat mobilization and can potentially improve diarrhea and respiratory disease but does not affect growth outcomes after arrival to calf-raisers.