Measurement of adaptive and innate immune function in calves raised under traditional and accelerated growth regimens

Hengst, Brittany
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University of Delaware
This study compared conventional and accelerated milk replacer feeding regimens on growth, respiratory and digestive health, vaccination response, and neutrophil mRNA levels. Holstein calves (10 male and 5 female) were randomly assigned to a 10-week study on their second day of life. Treatments were control (CON; n = 8) and accelerated (ACC; n = 7) milk replacer feeding programs. CON calves were fed a 20% crude protein (CP) and 20% fat milk replacer (Advance Calvita Supreme; Milk Specialities Global, Carpentersville, IL) at 1.25% birth body weight daily from weeks 1 through 6 of life and 0.625% birth body weight daily during week 7. A 28.5% CP and 15% fat milk replacer (Advance Excelerate; Milk Specialities Global, Carpentersville, IL) was fed to ACC calves at 1.5% birth body weight daily during week 1, 2% current body weight daily from weeks 2 through 6, and 1% current body weight daily during week 7. All calves were given milk replacer twice daily during weeks 1 though 6, once daily during week 7, and were completely weaned during week 8. Calf starter intake was measured daily through week 8. Body weight and wither height were measured weekly. Fecal scores (1 = firm to 4 = liquid) and respiratory scores (1 = normal; 2 = abnormal) were recorded twice daily. Neutrophils were isolated from blood at weeks 1, 3, 5, and 8. Quantitative PCR was used to measure neutrophil mRNA levels of 9 functionality genes: L-selectin, BPI, IL-1R1, TNF-αR, TLR-2, TLR-4, SOD1, MPO, and NCF1. Adaptive immune function was measured by vaccinating calves against ovalbumin at weeks 1, 3, and 5 and measuring serum anti-ovalbumin IgG concentration at weeks 1, 3, 5, and 8. There was no treatment effect on wither height, respiratory score, or serum anti-ovalbumin IgG concentration. Body weight during weeks 4 through 10 was greater for ACC than CON calves (P < 0.01). Calf starter intake was greater for CON than ACC calves during weeks 4 through 7 (P < 0.01), with no difference during week 8. CON calves had firmer feces than ACC calves (fecal score 1.4 vs. 1.7, P = 0.02). Neutrophil Lselectin mRNA levels were 51% greater in ACC than CON calves (P = 0.03). Feeding calves a 28.5% CP and 15% fat milk replacer in an accelerated feeding regimen increased growth and may enhance innate immune function, as indicated by the increased neutrophil mRNA levels of L-selectin.