Physiological and Nutritional Effects on Animals of Feeding Chemically Treated Wheat Straw

Two series of experiments were conducted to determine the long term effects of feeding NaOH treated diet to steers and to compare NaOH treated and NH3 treated diets. The three diets used in the experiments were based on 60% of untreated, 5% NaOH treated or 3.5% NH3 treated Neepawa wheat straw. The dry matter digestibility of the diets were not significantly (P > 0.05) different between treatments. Organic matter, nitrogen free extract (NFE), crude fiber (CF) and digestible energy were significantly (P < 0.05) higher for the NaOH treated diet. Mean dry matter intakes (g/kgW 0.75) were not significantly (P > 0.05) different between treatments. Feed conversion efficiency was significantly (P < 0.05) higher for the NaOH diet compared to the control or NH3 diet. Sodium hydroxide treatment significantly (P < 0.05) increased urinary nitrogen in the short term. Nitrogen retention increased significantly (P < 0.05) in the long term for all treatments especially by steers fed the control diet. There was consistently low nitrogen retention by the steers fed the NH3 diet compared to those fed the control or NaOH diet. Total volatile fatty acids (VFA) concentration in rumen fluid of steers fed NaOH treated diet was significantly (P 0.05) treatment differences in molar proportions of acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acids. However, acetic and propionic acids tended to decrease with time while n-butyric acid increased for all treatments. Iso-butyric, iso-valeric and n-valeric tended to decrease with time in the rumen fluid of steers fed NaOH diet. Rumen fluid sodium, potassium and chloride concentrations decreased in the long term for all treatments. Potassium concentration, however, was significantly (P < 0.05) higher in the rumen fluid of steers fed NaOH diet compared to that of the control and NH3 group. Osmolarity decreased with time for all treatments but remained significantly (P < 0.05) higher for the NaOH treatment throughout the experimental period. Rumen fluid pH was relatively low for the NaOH treatment. The steers fed NaOH treated diet increased water intake (liters/day) by 40.7% in the short term and by 19.3% in the long term compared with the control. Urinary excretion by the same steers increased by 215% and 63% during the short and long terms respectively over the control. Fecal water and urine volumes (liters/day) of steers fed NaOH treated diet declined by 55 and 86.4% respectively in the long term. Sodium hydroxide treatment increased urinary sodium by 84 and 58.3 g/day respectively in the short and long term over the control. Larger quantity of potassium (g/day) was also excreted in the urine by steers on the NaOH diet, though its concentration (mEq/1) was higher for the control and NH3 treatments. The concentration of chloride decreased with time and was lowest for the NaOH diet. Urinary urea, creatinine and osmolarity were (P 0.05) treatment difference in urine specific gravity. The urinary pH was significantly (P 0.05) treatment difference was found in the long term. High sodium intake had more negative effect on potassium balance in the short term. Despite the increased intake of sodium, steers fed the NaOH diet were able to maintain their plasma sodium level relatively constant within the normal range. High intake of sodium also had little effect on the plasma level of potassium, calcium, magnesium, phosphorus, chloride and bicarbonate. No consistent result was obtained with blood carbon dioxide and oxygen. Blood hematology was not affected by NaOH or NH3 treatment. Microscopic examination of the kidney, liver, and rumen tissues showed little evidence of pathological changes in the organs. Steers fed the NaOH diet gained 25.3% faster and had 36.9% better feed conversion compared with the control. No significant (P > 0.05) treatment difference was found between the control and NH3 diets. Heavier carcasses were obtained from steers fed the NaOH diet compared with the control. There was little differences between treatments in dressing percentage and ribeye area. Fat over rib was significantly (P < 0.05) higher for carcasses from steers fed the NaOH treated diet. The ability of steers to adapt to prolonged ingestion of the 5% NaOH treated diet and show improved performance was demonstrated