Calcium and Phosphorus Metabolism as Influenced by Dietary Protein Source and Cereal Processing in Crossbred Calves

Thirty crossbred calves (day old, approx. 26 kg) were assigned at random to six dietary groups in a 3 x 2 factorial design involving three sources of protein (viz. groundnut cake, GN; cottonseed meal, CS; meat and bone meal, MB) alongwith two methods of processing of maize (viz. grinding, M; griding followed by pressure cooking, MP). Milk was fed upto 56d of age. The respective calf starters along with green oats (Avena sativa) were made available to the experimental calves for a period of 90d, following which a metabolism trial was conducted. The daily intake, excretion and retention of calcium did not vary significantly (P<0.05) among dietary treatments. However, calves fed processed maize and cottonseed meal tended to exhibit comparatively higher and lower calcium retention, respectively. The calves fed MP-GN, M-MB and MP-MB diets consumed significantly (P<0.05) more phosphorus than those on other diets which in turn, was translated into higher (P<0.01) retentions. The calves fed CS diets retained significantly (P<0.01) lesser phosphorus which commensurated with the reduced (P<0.01) intake. Inclusion of processed maize in place of raw one resulted in a significantly higher (P<0.05) intake of phosphorus which was reflected in an increased (P<0.05) retention by the calves on these diets. Serum levels of calcium and inorganic phosphorus were similar (P>0.05), whereas, the alkaline phosphatase activity varied significantly due to dietary variations (P<0.05) and method of cereal processing (P<0.01). The calcium and phosphorus metabolism could, therefore, be optimized by dietary manipulation of protein sources. Futher, thermal processing of maize could enhance phosphorus utilization without affecting calcium metabolism.