Effects of dilution of colostrum replacer on IgG absorption, abomasal emptying rate, and gastrointestinal permeability in newborn Holstein calves.

The objective of this study was to determine whether increasing the dilution of colostrum replacer (CR) meals to reduce TS influences serum IgG concentration, apparent efficiency of absorption (AEA), abomasal emptying rate, and gastrointestinal permeability in newborn calves. Forty-eight newborn male Holstein calves (46.9 ± 3.70 kg) were randomly assigned to receive a single CR meal (949 g, providing 150 g of IgG) via esophageal tube within 1 h after birth at different final volumes (FV). Different TS concentrations were created by mixing the CR powder with varying amounts of water giving 4 dose-response treatment groups: control (n = 12) received 949 g of CR powder in 1.791 kg of water (FV = 2.64 L and TS = 360 g/L); dilution 1 (DL-1; n = 12) received 949 g of CR powder in 2.083 kg water (FV = 2.97 L and TS = 320 g/L); dilution 2 (DL-2; n = 12) received 949 g of CR powder in 2.574 kg water (FV = 3.39 L and TS = 280 g/L); and dilution 3 (DL-3; n = 12) received 949 g of CR powder in 3.110 kg water (FV = 3.96 L and TS = 240 g/L). After CR feeding, 6 calves/treatment were catheterized for blood sampling at 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 36, and 48 h post-CR feeding to assess abomasal emptying via acetaminophen. At 24 h, the same subset received lactulose, d-mannitol, and Cr-EDTA via esophageal feeder to evaluate gastrointestinal permeability, with blood being collected at 24, 26, 28, 30, and 32 h relative to CR feeding. Noncatheterized calves were blood sampled via jugular venipuncture at 0, 12, 24, 36, and 48 h relative to CR feeding, and daily thereafter from d 3 to d 7. Body weight was recorded at birth, at 48 h, and at 7 d. Body weight, ADG at 48 h, and ADG at d 7, serum total protein, AEA, and abomasal emptying rate did not differ among treatments. No differences in IgG absorption were observed, except for IgG area under the curve at 24 h (IgGAUC24) and d 7 (IgGAUCd7). The IgGAUC24 was greater in DL-2 (225.4 ± 18.9 mg·h/mL) and DL-3 (221.2 ± 18.9 mg·h/mL) compared with DL-1 (156.7 ± 18.9 mg·h/mL), with control (191.7 ± 18.9 mg·h/mL) showing intermediate values. Further, IgGAUCd7 was greater in DL-3 (11.7 ± 0.39 mg·h/mL) compared with the control (8.9 ± 0.39 mg·h/mL), with DL-1 and DL-2 showing intermediate values. No time-by-treatment differences were observed in postprandial concentrations of lactulose, d-mannitol, and Cr-EDTA. However, a difference was observed in the time to reach maximum chromium concentration, which was shorter in DL-3 calves (5.7 ± 0.47 h) compared with control (7.6 ± 0.47 h), DL-1 (7.3 ± 0.47 h), and DL-2 (7.3 ± 0.47 h). Results from the present study show that decreasing the osmolality of CR by adding water had minimal effect on overall IgG absorption, abomasal emptying rate, and gastrointestinal permeability in newborn calves.