Holstein calves fed non-saleable milk that was pasteurized or raw had decreased incidence of abnormal feces and hematology measures than calves fed accelerated milk replacer
The objectives were to determine the health and blood parameters before, during, and after weaning of 114 Holstein heifers fed either accelerated milk-replacer (Mrp; 28% CP, 18% fat), or non-saleable milk (3.59 ± 0.28% True-Protein; 4.12 ± 0.37% fat) that was either pasteurized (Pst) or raw (Raw; refrigerated and fed <24 h after collection). Calves were randomly assigned feeding treatments at age 0 d. Colostrum (1 L) was fed in less than 14 h after birth (Mrp and Pst = pasteurized colostrum; Raw=raw colostrum). All calves were bottle-fed 1.8 ± 0.20 SD L, 3xdaily; all calves were provided fresh water and grain ad libitum throughout the experiment. Calves began step-down weaning at age 5 wk and completed weaning at age 6 wk. Blood samples were collected at ages 3, 5, and 7 wk and were analyzed for complete blood counts (CBC) using a Procyte Idexx Analyzer. In addition, whole blood was tested for bactericide capacity against live E. coli 51813 (%Bact). Fecal scores were observed twice daily, on a 1-3 scale (FS1 = normal, FS2 = loose, FS3 = scours). The Mrp-fed calves had more (P < 0.01) observations (%obs) with FS2 than the Pst- and Raw-fed calves (13.2 vs. 7.32 and 8.9 ±0.69 %obs, respectively), although there were few scouring (FS3; 0.36 ±0.01 %obs) incidences in this experiment. Likewise, Mrp-fed calves had greater hematocrit % compared to the other calves (P < 0.01), but Pst- and Raw-fed calves had similar hematocrit % (32.4 vs. 27.9 and 28.4 ± 0.55%, respectively). At age 3 wk, Mrp-fed calves had greater circulating monocytes (P = 0.02) compared to the other calves, but there were no differences between Pst- and Raw-fed calves (10.4 vs. 9.2 and 8.2 +0.40%, respectively). Although there were no differences among treatments for %Bact or other hematological measures (P > 0.10), all calves had lower Neutrophil:Lymphocyte, more circulating monocytes and greater %Bact at age 7 wk compared to ages 3 and 5 wk (P< 0.05), suggesting that the change in diet from milk or MR to grain influences innate immune and hematological measures. The increased incidence of abnormal fecal scores among Mrp-fed calves and higher hematocrit percentages needs further consideration, especially before age 3 wk. In addition, these findings suggest that raw milk may be adequate for maintaining healthy CBC and fecal score measures on a well-managed, low-disease incidence dairy.
Keywords: milk replacer, pasteurization, calves, hematology