Assessment of Sodium Requirements of Grazing Beef Cattle: a Review

Publisher Website
Google Scholar
Abstract
Although grazing cattle generally freely consume supplemental salt (NaCl), the necessity of providing sodium additional to that in the feed has almost universally been accepted without evaluation. Techniques proposed for detection of Na inadequacy of cattle are reviewed and it is concluded that parotid salivary Na:K ratio and adrenal histology are the most sensitive indices of Na inadequacy. However, while saliva is a readily sampled body fluid, narrow Na:K ratios are not always associated with production responses to supplemental Na. The concentration of Na in blood plasma is not regarded as a useful index of Na inadequacy in cattle. Caution is advocated in the interpretation of analysis of animal pastures for Na, as Na concentration in forage may exhibit marked seasonal variation. The minimal Na requirement for nonlactating beef cattle does not appear to exceed .06 to .08% Na in the DM, and for lactation beef cows, .1% Na in the DM appears adequate.