Effects of feeding Saccharomyces cerevisiae fermentation products on the health of Holstein dairy calves following a lipopolysaccharide challenge

Abstract

Before weaning, dairy calves are at high risk for illness, especially respiratory and digestive diseases, which reduces average daily gain, age at first calving, and first-lactation milk production. Although these illnesses are commonly treated with antibiotics, efforts are being made to reduce antibiotic use, due to concerns about antibiotic-resistant bacteria. The objective was to evaluate the effects of Saccharomyces cerevisiae fermentation products (SCFP) on the immune status of calves, following a lipopolysaccharide (LPS) challenge administered just before weaning. Thirty Holstein bull calves were blocked based on initial body weight and then assigned to 1 of 2 study treatments. The control group (CON) was fed a 24% crude protein:17% fat milk replacer (MR) and calf starter with no SCFP added. The SCFP treatment was fed the same 24% crude protein:17% fat MR with 1 g/d of SmartCare (Diamond V) and calf starter with 0.8% NutriTek (Diamond V). SmartCare and NutriTek are both produced from anaerobic fermentation of S. cerevisiae. Calves were offered 2.84 L (12.5% solids) of MR twice daily at 0630 and 1630 h through d 51; from d 52 to 56, calves were fed MR once daily at 0630 h; and calves were weaned on d 57. Calves also received ad libitum access to a texturized calf starter and water. On d 50, a subset of calves (n = 20, 10 calves per treatment) were enrolled in an LPS challenge. At -1.5, -0.5, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, and 24 h relative to dosing with LPS, 20 mL of blood was collected, and rectal temperature and respiration rate were measured for each calf. Blood serum samples were analyzed for interleukin 6, TNF-α (tumor necrosis factor-α), interferon-gamma, haptoglobin, serum amyloid-A, fibrinogen, nonesterified fatty acid, cortisol, and glucose. This study observed increased concentrations of TNF-α at 1 h and 1.5 h and glucose at 0.5 h after dosing with LPS in SCFP calves compared with CON. Calves supplemented with SCFP also had an increase in respiration rate 0.5 h after dosing with LPS and reduced feed intake the day of the challenge compared with CON calves. These results suggest that dairy calves supplemented with SCFP exhibit an increased acute immune response, as observed by increased TNF-α, glucose, and respiration rate immediately after dosing with LPS, compared with CON calves.