Sulphur levels in saliva as an estimation of sulphur status in cattle: a validation study

Effective assessment of sulphur (S) status in cattle is important for optimal health,
yet remains difficult. Rumen fluid S concentrations are preferred, but difficult to
sample under practical conditions. This study aimed to evaluate salivary S
concentration as estimator of S status in cattle. Saliva and rumen fluid samples
were collected from dairy cows (n = 16) as well as samples of different feedstuffs
offered to the animals. The N and S concentrations were determined using the
Dumas technique. The average dietary N and S content were calculated as well as
N:S ratio of saliva, rumen fluid and diet. Salivary S concentrations could not
predict rumen fluid or dietary S concentrations (p 4 0.05). The log transformed
salivary N:S ratio (x) could predict the rumen fluid N:S ratio (y) with a linear
equation of y = 9.83 (±4.59) x þ 0.39 (±4.56) (r = 0.497, p = 0.05), but left too much residual variation to serve as reliable predictor. Further research should
investigate this relationship in the search for an S status estimator.