The Studies On The Metabolism And Requirements Of Calcium And Phosphorus For The Growing Boer Crossbred Goat

The following three experiments measure the calcium and phosphorus metabolismof growing crossbred Boer goats (a crossbreed between male Boer goats andfemale Saanen goats), in an effort to determine the calcium and phosphorusrequirements of those crossbred Boer goats.The first experiment involved eight 3-month old crossbred Boer goats. Theywere given four differently formulated rations with different target body weights.The sensitivity indexes were determined in relation to the metabolism of calciumand phosphorus. In this study, two formulas were derived showing therelationship between the metabolism of calcium and phosphorus with the averagedaily gain (ADG) (G ,g/d), DMI ( g/d), and the daily calcium intake (I, g/d). d-Ca＝0.4765*I＋0.0021DMI－0.0017G－1.6356 (R2=0.948,P<0.001) d-P＝－1.001*I＋0.0037DMI－0.0022G－0.9208 (R2=0.672, P<0.05)The second experiment involved eight 14-month old crossbred Boer goats. Inorder to measure the effect of calcium content on calcium and phosphorusmetabolism, these goats were given four different base rations of various calciumcontent (1.36 g/d,3.65g/d,7.16g/d,11.77g/d). In this study, two formulas werederived showing the relationship between the daily calcium intake (X, g/d) withADG(G, g/d) and the metabolism of calcium(Y, g/d). Y＝－0.0259 X2+ 0.4569X－0.6715 R2=0.9937 P<0.001 G＝－1.1416 X2+15.677X+142.28 R2=0.8388 P<0.001The third experiment involved eight 15-month old crossbred Boer goats. In orderto measure the effect of phosphorus content on calcium and phosphorusmetabolism, these goats were given four different base rations of variousphosphorus content (0.89g/d,1.31g/d,2.55g/d,4.16g/d). In this study, twoformulas were derived showing the relationship between the daily phosphorusintake (X, g/d) with ADG(G, g/d) and the metabolism of phosphorus (Y, g/d). Y＝－0.157X2+0.848X－0.751 R2=0.9459 P<0.001 G＝－21.83X2+108.86X－57.53 R2=0.9905 P<0.001生长期波杂山羊钙磷代谢规律及需要量研究 This research on the calcium and phosphorus metabolism of crossbred Boer goatshas yielded the following insights: first, rations low in calcium or phosphorusresult in an internal calcium and phosphorus metabolic imbalance. Second,calcium absorption decreases as the calcium content in the ration increases. Third,because the inherent rate of phosphorus absorption is relatively high, rations withhigh concentrations of phosphorus have serious effects on the rate of phosphorusabsorption. Fourth, serum activity of PTH and AKP is cyclic in nature; thisactivity is also sensitive to changes in plasma concentration of calcium andphosphorus.This research has also identified the calcium and phosphorus maintenance andgrowth requirements of crossbred Boer goats at the 14 and 15 month stages ofdevelopment. 14-month old crossbred Boer goats have a calcium maintenancerequirement of 22.4 mg/kgLW/d and a calcium growth requirement of 5.73g/kgLWG; 15-month old crossbred Boer goats have a phosphorus maintenancerequirement of 25 mg/kgLW/d and a phosphorus growth requirement of 4.95g/kgLWG.