Influences of increasing levels of sulfate in drinking water on the intake and use of low-quality forages by beef cattle

Abstract

Objective. This study evaluated the effects of varying sulfate concentrations of water on forage and water intake, digestibility, digestive kinetics, and rumen fermentation characteristics of cattle consuming low-quality forages provided a protein supplement, with and without salt. Materials and Methods. Eight ruminally cannulated cows (2 yr of age) were used in 2 concurrent 4 × 4 Latin squares (4 cows per square) to test the effects of increasing water sulfate concentrations on forage and water intake, digestibility, digestive kinetics, and rumen fermentation characteristics of cattle consuming low-quality forages provided protein supplement with and without salt. Within each square, cows were randomly assigned to the following treatments: (1) control (<10 mg/L sulfate); (2) 473 mg/L; (3) 946 mg/L; and (4) 1,420 mg/L. All cattle were provided a crude protein supplement at 0.18% of BW daily (0800 h daily); however, protein supplement NaCl composition differed by square (no NaCl vs. addition of 25% NaCl). Each period consisted of a 14-d adaptation period, followed by a 7-d intake and digestion period with ruminal profiles conducted on d 22 and complete ruminal evacuations on d 23, 5 h after feeding. Results and Discussion. There were no observed effects of sulfate (SO4) levels on forage intake, water intake, ruminal DM and liquid fill, ruminal DM and NDF digestibility, ruminal liquid passage rate, ruminal liquid turnover, ruminal liquid flow rate, ruminal pH, ruminal ammonia, ruminal total VFA concentrations, ruminal individual VFA concentrations, or the ruminal acetate-to-propionate ratio (P ≥ 0.16). Furthermore, the addition of 25% salt to supplement had no effect on forage intake, ruminal DM and liquid fill, DM and NDF digestibility, liquid passage rate, liquid turnover, liquid flow rate, ruminal pH, or the acetate-to-propionate ratio (P ≥ 0.24). Conversely, water intake was greater for animals provided 25% salt in supplement compared with animals not provided salt (P = 0.05). Implications and Applications. Sulfate water concentrations as high as 1,420 mg/L had minimal effects on intake, digestibility, and rumen fermentation characteristics of cattle consuming low-quality forage-based diets when provided a protein supplement containing up to 25% salt.