HIGH LEVELS OF SODIUM CHLORIDE IN SUPPLEMENTS FOR GROWING CATTLE

Two trials were conducted to evaluate the effects of high levels of sodium chloride in energy and (or) protein supplements on performance and digestive and metabolic parameters of growing beef cattle. In each trial, 24 Hereford steers averaging 196 kg initial weight were individually fed corn silage or fescue hay plus an energy and (or) protein supplement containing NaCl. Consumption of the low (LS) and high (HS) levels of NaCl was 22–23 g d−1 and 192–193 g d−1, respectively. In Trial 1 the high NaCl supplement tended to reduce gains and feed efficiency of steers fed silage whereas gains were similar for those fed low and high NaCl and fescue hay. In Trial 2, gains and feed efficiencies were similar for both NaCl treatments. Rumen fluid total volatile fatty acid concentrations were lower (P < 0.05) at day 70 of both trials with high NaCl. Steers fed high NaCl had lower rumen ammonia concentrations at days 56 and 70 of Trial 1, while no significant differences were noted at day 70 of Trial 2. Molar percentages of valeric acid were reduced at each sampling with high NaCl diets. Serum Na levels were similar for the two NaCl levels, whereas K levels were increased at day 70 due to high NaCl. Rumen liquid digesta flow rates were increased (P < 0.05) in animals fed the high NaCl supplements, whereas total solid digesta and soybean meal rate of passage were not affected by NaCl level in the supplement. Supplements containing high levels of NaCl do induce changes in rumen function but do not consistently affect animal performance. Key words: Sodium chloride, supplements, beef cattle, corn silage, fescue hay