Effects of colostrum feeding frequency on passive transfer immunity and growth in Holstein calves

The objective of this study was to examine the effect of feeding colostrum once versus twice on growth and passive transfer immunity (PTI) of preweaning Hol-stein calves by measuring BW, withers height (WH), as well as serum total protein (STP) and Brix values. On the day of birth (des-ignated as d 1), 70 Holstein calves were weighed and as-signed randomly to one of the colostrum feeding groups: 1-feeding, n = 34; or 2-feeding, n = 36. Both groups re-ceived 4 L of pasteurized high-quality first-milking colos-trum (Brix > 23%) between 2.5 and 3 h after birth. The 2-feeding group received an additional 2 L of first-milking colostrum 8 to 10 h after the first feeding. Thereafter, all calves were fed 3.5 L of pasteurized whole milk twice daily and provided ad libitum access to calf starter. Blood samples, WH, and BW were obtained on d 3 and 7. Also, WH and BW were measured on d 30 and 45. Health status was scored and recorded during the experiment. Serum Brix and STP were measured using digital and optical refractometers, respectively. The differences in Brix, STP, IgG, WH, and BW were analyzed by ANOVA, repeated measures. Body weight, WH, and ADG (d 1 to 45) were not different in calves fed 2 doses of pasteurized colostrum or fed 1 dose of colostrum. Fur-thermore, during the first 45 d after birth, no mortality or morbidity were observed in the 2 groups. Mean STP and Brix were affected by treatment and feeding frequency by day interaction. On d 3, mean STP and Brix were greater in 2-feeding than 1-feeding (STP: 7.4 vs. 7.1 ± 0.1 g/dL; Brix: 10.9% vs. 10.3% ± 0.1%), respectively. Mean STP and Brix decreased in both groups by d 7, but tended to be greater in 2-feeding than 1-feeding (STP: 7.3 vs. 6.5 ± 0.2 g/dL; Brix: 10.7% vs. 9.8% ± 0.2%). Well-established evidence supports the importance of colostrum quality, cleanliness, and timing for calf immunity, but the effects of feeding frequency on PTI and calf performance are in-consistent. Despite marginal differences in serum Brix and STP between the 1- and 2-feeding groups, both measures were above the recommended critical thresholds, sug-gesting that successful passive transfer of immunity was achieved with either 1 or 2 timely feedings of pasteurized high-quality colostrum. The colostrum frequency treat-ment did not influence the growth performance and health of preweaning calves.