Effects of feeding an organic-certified milk replacer to preweaning Jersey dairy calves on growth performance, blood metabolites, and economic efficiency.

We aimed to evaluate the effects of feeding organic-certified raw whole milk (WM) versus organic-certified milk replacer (MR) on growth performance, skeletal development, and blood metabolites in preweaning Jersey calves, and the economic efficiency of these 2 liquid feeding regimens. Thirty organic-certified Jersey calves (18 females and 12 males) averaging (mean ± SD) at birth 24.8 ± 2.31 kg (heifers) and 28.7 ± 1.80 kg (bulls), were assigned to WM (n = 15) or MR (22.1% crude fat, 21.3% CP; n = 15) in a randomized complete block design. Calves were fed 4 L/d of WM or MR until weaning at 8 wk of age. Starter intake was greater in calves receiving MR (329 g/d) than WM (178 g/d), particularly from wk 4 to 8. Compared with WM calves, MR calves had lower final BW (49.3 vs. 54.7 kg) and ADG (411 vs. 483 g/d). Heart girth (80.8 vs. 82.8 cm), withers height (72.3 vs. 73.9 cm), hip height (75.1 vs. 76.6 cm), and body length (72.9 vs. 75.6 cm) were all lower in MR than WM calves at wk 8 of age, with treatment by week interactions observed for heart girth and withers height. In addition, the plasma concentrations of glucose (98.8 vs. 106 mg/dL) and urea N (8.34 vs. 9.66 mg/dL) were lower with feeding MR than WM, with a treatment by week interaction seen for plasma urea N. However, the plasma concentrations of BHB and ketones did not differ between treatments. The economic analysis showed that feeding MR was less cost-effective than feeding WM due to increased total feed costs per calf (median = $228.89 vs. $157.31) and per kilogram of BW gain (median = $9.94 vs. $5.82). In conclusion, feeding MR to preweaning organic-certified Jersey calves reduced ADG, skeletal development, and profitability compared with WM.