The objective of this study was to evaluate the effects of incorporating 2 commonly used additives or spray-dried porcine plasma in calf milk replacer (CMR) on calf performance and health. Male Holstein calves (n = 158) transported from auction barns and local dairy farms were randomly assigned to receive 1 of 3 decoquinate-containing CMR for the first 49 d of the experiment: all milk protein and no additives (CONT); 15% of crude protein (CP) replaced with spray-dried porcine plasma, no additives (PLM); or all milk protein and an added combination of sodium butyrate (rate 1.4 kg of butyric acid/Mt) and Bacillus subtilis (1.28 million cfu/g of feed; BB). All milk replacers were formulated to contain 26% CP and 17% fat, 2.4% Lys, and 0.8% Met, and were bucket-fed at daily feeding rates of 520 g during wk 1 and 2, 650 g during wk 3, and 900 g during wk 4 and 5, in a total of 4, 5, and 6 L of solution, respectively. Calves were offered texturized calf starter (18% CP) upon arrival until wk 3 and transitioned to a corn and pellet ration with 2% straw (18.1% CP). No prophylactic administration of antibiotics occurred. All calves were gradually weaned over a 2-wk period. Calves were individually housed until weaned and then housed in groups of 5 in a mechanically ventilated facility in southwestern Ontario, Canada. Fecal scores, treatments administered (antibiotic or supportive therapy), and mortalities were recorded daily. Body weight was measured using a digital scale at arrival and at 14, 49, 56, and 78 d after arrival. No differences were found among the groups with respect to growth, feed efficiency, or incidence of diarrhea or respiratory infection treatment. Calves supplemented with BB had a greater hazard of mortality over the growing period compared with CONT. An interaction was found between the BB group and the level of total serum protein, with the BB group having a lower proportion of days with a fecal score of 3 when the calves had a higher total serum protein level. Calves fed PLM had a lower proportion of d with a fecal score of 3 relative to CONT but no difference in the proportion of d with a fecal score of 2 or higher. This study found that the addition of spraydried plasma in CMR reduced diarrhea severity; however, supplementing BB was associated with a higher hazard of calf mortality and had a varying response on fecal score.

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