Field Validation of a Commercial Pasteurization System for Heat-Treating Individual Bags of Bovine Colostrum

Our primary objective was to evaluate the effect of using a commercial pasteurizer system (Matilda Colostrum Pasteurizer and Warmer. DairyTech Inc., Windsor, CO) to heat-treat ( HT ) individual bags (3.8 L volume) of bovine colostrum, on IgG and bacteria concentrations, as compared with heat-treating larger volumes of pooled colostrum (>in a vat pasteurizer. A secondary objective was to describe concentrations of IgG and bacteria in pre-HT versus post-HT colostrum, whether processed using either the Matilda pasteurizer or a vat pasteurizer system, to HT small or large volumes, respectively. The study was conducted in summer 2024 on a commercial Midwest Holstein dairy. Each day, high quality (Brix >22%; estimated IgG >50 g/L) colostrum was selected and pooled to create a single unique batch (57–95 L (15–25 gal)), then transferred into the on-farm 144 L (30 gal) vat pasteurizer. After mixing well and aseptic sample collection for later testing, 3.8 L was transferred from the pool into a 4 L single use disposable bag (Perfect Udder( PU ) bag system, DairyTech Inc.) which was then placed in a small commercial colostrum pasteurizer system (Matilda Pasteurizer and Warmer, DairyTech Inc.). The large pool and the single bag of colostrum were both then HT in the vat pasteurizer ( VAT ) and Matilda Pasteurizer system ( MAT ), respectively, at 60°C (140°F) for 60 min. Following rapid cooling to 15.5°C (60°F), aseptic samples of post-HT colostrum were collected from both the VAT and MAT systems and frozen (−20°C) for later analysis. Pre-HT colostrum from the original fresh pool, and post-HT colostrum collected from both the VAT and MAT pasteurizer systems were submitted for determination of IgG concentration (g/L) using an RID assay, and aerobic culture to determine total plate count (TPC, cfu/mL) and total coliform count (TCC, cfu/mL). For objective 1, linear regression was used to evaluate if IgG, TPC or TCC in post-HT colostrum varied by HT method (VAT vs MAT). For objective 2, after stratifying the data by pasteurization method (VAT or MAT), linear regression was used to evaluate if IgG, TPC or TCC concentrations were different in pre- versus post-HT samples. Results from 24 unique batches of colostrum showed no effect of HT method on mean ± SE concentrations of IgG, TPC or TCC in post-HT colostrum processed using the VAT method (82.7 ± 2.19 g/L; 2.64 ± 0.14 log 10 cfu/mL; 0.20 ± 0.09 log 10 cfu/mL) as compared with the MAT method (82.9 ± 2.19 g/L; 2.96 ± 0.14 log 10 cfu/mL; 0.07 ± 0.09 log 10 cfu/mL). Furthermore, whether processing a larger volume in the VAT system, or a small volume in the MAT system, HT resulted in no reduction in IgG, but significantly reduced bacteria levels in post-HT (vs pre-HT) colostrum. These results show that, under the conditions of this study on a single commercial dairy farm, we achieved equally high quality and equally clean colostrum for calves, whether HT larger volumes using a vat pasteurizer system or small volumes in individual bags using the Matilda pasteurizer system.