Bioassays of Quality in Water Resources of Major Importance to New Mexico

Fifty-two samples of water from sources considered representative of several resources that are economically and/or ecologically important to New Mexico were analyzed chemically for major minerals and assayed for quality in terms of mouse growth, mouse reproduction and degradation of fibrous substrates by rumen microorganisms cultured in vitro. Chemical constituents measured and evaluated statistically in relation to bioassay data were: electrical conductivity, total dissolved solids, pH, hardness, Ca, Mg, Na, K, Cl, HCO ₃, CO ₃, and SO ₄. Samples were also tested semi-quantitatively for NO ₃, Cd, Hg, and Pb. Using waters which varied in mineralization from less than 100 to more than 4700 milligrams of total dissolved solids per liter, mouse growth and reproduction were not significantly affected by water sources (P >.05), even though precision was sufficient to detect differences in growth of about 5 percent from the population means. Water sources markedly affected the degradation of fibrous substrates by rumen cultures, especially when purified cellulose rather than forage (alfalfa hay) was used as the substrate. The results indicate that the mouse is insensitive, in terms of growth and reproduction, to differences in quality of drinking water, at least in regard to the degree of gross mineralization; whereas, cultures of rumen microorganisms respond to changes in apparent quality of water which have been poorly documented and are apparently poorly defined to date. The data suggest that mineralized waters in certain major resources of New Mexico may have greater potential for usage in animal production than would be expected from standards of water quality currently in usage.

Project No. A-029-NMEX