Physiological responses to a yeast and clay-based adsorbent during an aflatoxin challenge in Holstein cows

The objective of this study was to determine the effects of 2 different adsorbents (AD) composed of yeast fractions and bentonite (AD1 and AD2) during an aflatoxin (AF) challenge on the health and performance of lactating dairy cows. Lactating Holstein cows [(n = 76); BW (mean ± SD) = 698 ± 72 kg; DIM = 153 ± 83 d] were assigned to 1 of 5 treatments in a randomized complete block design. The trial lasted 28 d and measurements were made from d 22 to 28. From d 22 to 24 cows received an AF challenge (100 μg of AFB₁/kg of diet DM administered orally). Treatments were: control (CON), no AD or AF; positive control (POS), no AD plus AF challenge; 30 g per cow per day of AD1 and AF challenge (P30); 60 g per cow per day of AD1 and AF challenge (P60); and 60 g per cow per day of AD2 and AF challenge (PROT). The appearance and disappearance of AF excreted in milk was tested at each milking from d 22 to 28 using SNAP tests (SNP; IDEXX, Inc.). Blood was sampled on d 22 and 26 (n = 2 per cow), and analyzed for superoxide dismutase (SOD) concentration. Milk samples from d 22 to 26 were analyzed for AFM₁ concentrations by HPLC. Fecal samples collected from the rectum on d 22 and 24 were analyzed for AFB₁ concentrations via HPLC. Statistical analysis was performed using the MIXED procedure of SAS. A quadratic treatment effect (P < 0.001) was observed for plasma SOD concentrations at 2.77, 1.99, and 1.97 ± 0.05 U/mL for POS, AD30, and AD60 treatments, respectively. Aflatoxin M₁ transfer (11.4 and 0.00 ± 1.60 g/kg), excretion (29.52 and 0.00 ± 4.58 μg/d), and concentrations in milk (0.76 and 0.00 ± 0.16 μg/kg) were greater for POS than CON, respectively (P < 0.001) but no differences were observed among other treatments. A tendency for a quadratic treatment effect (P = 0.08) was observed for fecal AFB₁ concentrations at 6.78, 8.55, and 5.07 ± 1.17 μg/kg for the POS, P30, and P60 treatments, respectively. Oral supplementation of yeast and bentonite clay-based adsorbents during an AF challenge resulted in quadratic changes in plasma SOD and fecal AFB₁ concentrations; however, no differences were observed for DMI or milk yield. In conclusion, yeast cell wall and bentonite-based adsorbent may be beneficial in reducing inflammation during an AF challenge but there were no treatment differences regarding its adsorbent capacity.