Impact of increasing NaCl levels in livestock drinking water on the intake and utilization of low-quality forages by beef cattle

Abstract

Water is one of the most important nutrients for livestock production (Petersen et al., 2015) but its quality is often overlooked in western range settings. The western United States and more specifically, Montana, are prone to variable precipitation and droughts, reducing the quantity and quality of livestock drinking water as well as limited forage quality/quantity. Dormant season grazing of rangeland forages often involves utilizing self-fed, salt limited supplements to meet cattle nutrition requirements and better utilize forage. Self-fed supplements commonly add salt as an intake limiter because it is effective, cheap and necessary in beef cattle diets (Cardon et al., 1951). The objective of this study was to evaluate the impacts of increasing NaCl levels in water on low quality forage intake, digestibility, and rumen fermentation of cattle consuming low quality forage. Eight, ruminally-cannulated, Angus crossbred cows were individually stalled and used in two 4 x 4 Latin squares design. One square was hand fed a non-salt supplement; the second square was fed a salt limiting supplement. Two cows (one from each square) were assigned to one of four water treatments per period: 1) control, no added NaCl; 2) 1000 mg NaCl/L; 3) 2000 mg NaCl/L; and 4) 3000 mg NaCl/L. A 14-day adaption period allowed cattle to acclimate to the water; followed by a 6-day total collection period. Rumen fluid samples were collected on day 22 at hours 0, 4, 8, 12, 18 and 24; and on day 23 a total rumen evacuation was conducted to determine total rumen volume and collect rumen content samples. Increasing levels of NaCl did not influence intake in either study (P > or = 0.36). Rumen pH was influenced by water NaCl in study 1 (P = 0.01), however, post hoc analysis revealed no differences. Volatile fatty acids in both studies were not affected by NaCl in either study (P > or = 0.39). Our results suggest the NaCl levels in our study may have little influence on intake, rumen fermentation and liquid kinetics suggesting NaCl levels up to 3,000 are safe for cattle.