EFFECTS OF MOLYBDENUM AND SULFUR ON MINERALS IN THE DIGESTIVE TRACT OF STEERS

Abstract

Four Holstein steers with cannulae in the rumen, proximal duodenum (PD) and terminal ileum (TI) were fed diets containing: (1) no added Mo or S; (2) Mo added at 10 mg kg−1; (3) S added at 3.0 g kg−1; and (4) Mo and S added at 10 mg and 3.0 g kg−1, respectively, in a Latin square design. Effects of Mo and S on minerals in the digestive tract of steers were evaluated. The solubility of Cu was lower with Mo (P < 0.01) and S (P < 0.01) at the PD and TI, and with Mo plus S (P < 0.05) at the TI. With Mo more (P = 0.07) Cu tended to be excreted in feces. Effects of Mo: Mn, reduced (P < 0.05) input to stomach region and higher (P < 0.01) absorption distal to PD; Zn, lower (P < 0.01) solubility at TI with less (P < 0.05) absorbed from large intestine (LI); Fe, more (P = 0.06) absorbed from LI with lower (P < 0.01) fecal excretion; P, lower (P < 0.05) input to stomach region with a tendency for less (P = 0.08) absorbed from small intestine (SI); Na, less (P < 0.05) absorbed from LI; K, lower (P < 0.05) apparent digestibility. Effects of S: Mn, slight tendency for higher (P = 0.10) absorption distal to PD; Zn, lower (P < 0.05) solubility at PD; P, less (P < 0.05) absorbed from SI and LI; Mg, tendency for less (P = 0.07) absorbed from stomach region and trend for more (P = 0.08) absorbed distal to PD. Minerals other than Cu were influenced by Mo and S in the digestive tract of cattle. Key words: Cattle, molybdenum, sulfur, digestion, minerals