Effects of feeding mycotoxin-contaminated diets and the use of an adsorbent on the intake, digestibility, rumen fermentation, nitrogen balance and physiological parameters in the blood of Nellore steers

Abstract

The study objective was to investigate the effects of mycotoxin contaminated diets and the use of an adsorbent (yeast cell wall extract; YCWE) on the intake, digestibility, rumen fermentation, nitrogen balance and physiological parameters in the blood of Nellore steers. Eight rumen-cannulated Nellore steers (initial BW = 417 ± 42 kg) were used in a 4 × 4 replicated Latin square design. A 2 × 2 factorial treatment structure was used to investigate the effects of mycotoxin contamination of the diet, the use of a mycotoxin adsorbent and their interactions. The dietary contamination consisted of: (1) diet without mycotoxins (CTRL), and (2) control diet added mycotoxins (MYCOT). The second factor was: (1) absence (YCWE–) or (2) presence (YCWE+) of YCWE. Mycotoxin contamination negatively affected dry matter intake during the first week of treatment application (P = 0.05) and tended to lower intake during the sampling period (P = 0.08). MYCOT resulted in lower (P = 0.03) digestibility of neutral detergent fiber and tended to lower (P = 0.08) ruminal pH compared with CTRL. There was MYCOT × YCWE interaction on the proportion of isovalerate (P < 0.01) and trend on the proportion of valerate (P = 0.08) in the rumen. There was also an effect of MYCOT (P = 0.04) and a trend of YCWE (P = 0.10) on the proportion of isobutyrate. Animals received MYCOT treatments had higher N excretion in the urine (P = 0.01), and consequently lower N retention (P = 0.05). There was MYCOT × YCWE interaction effect (P = 0.04) on the serum glucose concentration, where the MYCOT YCWE– treatment had a higher glucose concentration than the CTRL YCWE–, and the use of YCWE in MYCOT diet resulted in a concentration similar to CTRL treatments. The use of YCWE resulted in higher (P = 0.03) serum concentration of total proteins and lower (P < 0.01) proportion of ceruloplasmin. Animals fed mycotoxins had a lower (P < 0.01) proportion of IgA. MYCOT × YCWE effects (P < 0.01) on hemoglobin concentration and hematocrit were observed, where MYCOT had lower concentrations than the control and the use of YCWE in the contaminated diet resulted in values similar to CTRL. Animals fed mycotoxins tended to have lower (P = 0.08) number of lymphocytes and had lower (P = 0.02) lymphocytes: neutrophils ratios. This study suggests that mycotoxins may have negative impacts on certain physiological parameters that can influence health and performance of beef cattle, and the use of YCWE can mitigate some of these negative changes.