It was hypothesized that the hypocalcemia, hyperphosphoremia, hyperkalemia and the mild hypochromic microcytic anemia which existed in cattle afflicted with brisket disease could be due, at least in part, to nutritional disturbances. A chemical composition study was made of seven monocotyledonous plant species that comprise a major part of the diet and nine dicotyledonous plant species consumed by cattle and known or suspected of being poisonous. The plants analyzed we re collected from two cattle grazing allotments, 7-mile and UM, in the Fishlake District, Fishlake National Forest, Utah, where brisket disease incidence is high. In each species the percentages on dry matter basis, of calcium, magnesium, potassium, sodium, copper, cobalt, iron, manganese, molybdenum, zinc, chloride, phosphorus and oxalate were determined. The first ten elements listed were measured by atomic absorption spectrophotometry by modifications of the methods used by Allan (1961 ) and David (1962). Oxalate content was determined by a modification of the method used by Dye (1959). Phosphorus content was determined colorimetrically by a modification of the method used by Fiske and SubbaRow (1925). Chloride content was determined by a micro-titration method used at U.S. Salinity Laboratories. Results obtained showed that the monocotyledonous plant species were low in calcium content when compared to values reported in the literature for grass and legume species and when compared to calcium requirement for beef cattle. The hypothesis that hypocalcemia in cattle afflicted with brisket disease is due to inadequate dietary intake gains support. The quantities of oxalates in the plant species studied were substantial enough to depress an already low dietary calcium level. It was not determined if oxalate ingested was of sufficient magnitude to cause renal and nervous lesions and erythrocyte destruction. Potassium content of the monocot species in the plant study was high compared to plants that normally comprise cattle diets and hyperkalemia in cattle afflicted with brisket disease could be of dietary origin. Sodium content of each of the plants studied was below the level required to satisfy body needs and could not be responsible or contributary to the edema that occurs in brisket disease. The plant species contained large quantities of iron, manganese and copper, much in excess of nutritional requirements. The anemia that accompanies brisket disease could be related to dietary excesses of these elements. Zinc requirement in cattle is not known, but if the requirement is comparable to that of swine, the plants studied provide an adequate quantity of this element. The contents of cobalt and molybdenum were too little to be measured by atomic absorption spectrophotometry. There may be a cobalt deficiency in cattle grazing these forages.

Brisket disease, an affliction of cattle, is important because of : (1) economic losses, (2) similarities to chronic mountain sickness in humans, and (3) the provision of experimental animals for cardiac research. In afflicted cattle, right cardiac ventricular hypertrophy and dilatation occur and are manifestations of attempted compensation for reduced alveolar oxygen by increasing pulmonary circulation. Geographic variations in occurrence of brisket disease in Utah indicate that hypoxia is not the sole causative factor. From the findings that afflicted cattle exhibit hypocalcemia and hyperkalemia, and the disease occurs most commonly in wet meadowland environments where potassium is high and calcium low in browse, a dual stress theory of cause was hypothesized; i.e., altitude-induced hypoxia plus ionic calcium-potassium imbalance. To test the hypothesis, 40 Hereford calves were randomized into four equal groups, two at 1,372 meters (normal) and two at 2,745 meters (hypoxic) elevation. At each elevation there were control (balanced) and treated (calcium-potassium) groups. For 16 weeks, treated calves received, by diet, one-fourth the calcium and 10 times the potassium requirements; also, repeated injections of dipotassium ethylenediaminetetraacetate, potassium chloride, and an aldosterone inhibitor to further induce hypocalcemia and hyperkalemia. Control groups at each elevation received a balanced diet and no injections. Since optimal myocardial function is dependent upon proper ion balance, and concentrations of calcium, potassium, sodium, phosphorus, magnesium, chloride, iron, zinc, and copper in blood, heart, liver, kidney, and bone are indices, these elements were quantitated. Calcium concentration in serum was reduced by 1.6 milligrams per 100 milliliters from an initial value of 9.4 milligrams per 100 milliliters, and an average increase of 1.8 milliequivalents per liter in potassium concentration in whole blood, from the initial concentration of 12. 4 milliequivalents per liter, occurred in treated calves . Elevation caused an increase of 1.7 milliequivalents per liter in potassium concentration in serum from the initial concentration of 6.2 milliequivalents per liter. Iron concentration in whole blood increased in response to hypoxia and decreased due to treatment. In the serum, sodium and copper decreased and chloride increased due to treatment. Compared to low elevation, significant tissue compositional changes in calves at high elevation were as follows: (l) calcium: kidney 12 percent higher, heart 9 percent lower: (2) sodium: liver 5 percent lower, kidney 3 percent higher: (2) phosphorus: kidney 2 percent higher. More profound changes occurred in cattle subjected to treatment: compared to controls, the tissue compositions in imbalanced cattle were as follows: (1) calcium: heart 10 percent and liver 13 percent lower, kidney 92 percent higher; (2) potassium: heart 13 percent higher, liver and kidney 6 percent lower; (3) sodium: heart 18 percent, liver 8 percent, and kidney 14 percent lower; (4) magnesium: heart 20 percent and liver 5 percent higher, kidney 11 percent lower; (5) phosphorus: heart 6 percent and kidney 21 percent higher, liver xvi 2 percent lower; (6) absolute dry matter: liver 5 percent and kidney 13 percent lower; (7) total ash: kidney 4 percent lower. In addition, iron, zinc, and copper were decreased in both cardiac and hepatic tissues of treated calves. Treatment influenced bone ash composition as follows: compared to controls, calcium decreased to 25.3 from 32.5 percent; phosphorus decreased to 16.5 from 19.0 percent; potassium increased to 0.16 from 0.08 percent; and zinc increased to 319 parts per million from 227 parts per million. High altitude was also influential. Compared to controls, phosphorus increased to 18.1 percent from 17.5 percent, potassium decreased to 0.112 from 0.129 percent, sodium to 1.09 from 1.17 percent, and magnesium to 0. 64 from 0.70 percent.

Twenty four cattle, six each of healthy cows and calves, and cows and calves with brisket disease, were obtained, examined and slaughtered, The concentrations of calcium, chloride, cobalt, copper, iron, magnesium, molybdenum, phosphorus, potassium, sodium and zinc; and percent absolute dry matter and percent ash were determined in tissues selected from the following: cardiac, hepatic, renal, osseous, whole blood and blood serum. In addition, certain physical and biological parameters were recorded for each animal. The results were analyzed as a 2 x 2 factorial, segregating the effects of age and brisket disease, and the age-disease interaction. The following statistically significant (P<0.05) differences were attributed to the effect of brisket disease: reduction in the percent dry matter and percent ash in all soft tissues studied; increase in cardiac, hepatic and renal calcium and sodium; decrease in serum total calcium; marked decrease in hepatic copper and increase in hepatic iron; decreased blood iron, hematocrit and hemoglobin; decreased hepatic potassium, magnesium and phosphorus; and increased hepatic zinc. The effects of brisket disease are superimposed upon these marked differences in the cattle in the present study as compared to those in a previous study of well nourished cattle of similar breeding from a similar environment: reduced cardiac, hepatic, serum and osseous calcium; reduced hepatic, osseous and serum magnesium and increased renal magnesium; reduced hepatic phosphorus and increased renal phosphorus; reduced hepatic, serum and osseous potassium and increased cardiac potassium; and reduced cardiac, osseous and serum sodium and zinc. The effects of age must be evaluated in view of the fact that half of the animals were diseased; moreover, some age effects occurred almost exclusively in the diseased animals. Statistically significant (P<0.05 ) differences attributed to the effect of age were: decreased phosphorus concentrations in hepatic and renal tissue and serum; increased percent dry matter in hepatic and osseous tissue; increased osseous percent ash; decreased hepatic and osseous potassium; increased serum ionic calcium; and decreased hepatic calcium, magnesium and sodium, all in cows as compared to calves. The interaction of increased age and brisket disease produced the following statistically significant (P<0.05) results: hepatic percent dry matter and iron concentration were increased; hepatic magnesium, potassium and sodium were decreased; and cardiac zinc was increased. Hypotheses regarding possible reasons for these results are formulated and discussed.