Effect Of Calcium Source And Level On Performance And Bioavailability Of Calcium And Phosphorus Of Weaning SD Rats And Pigs

Two experiments were designed in our study. Experiment1was conducted to investigate the effects of diet supplemented calcium carbonate, calcium citrate or calcium formate on performance, femur development, calcium and phosphorus availability in weaning SD rats; Experiment2was conducted to investigate the effects of diet supplemented different calcium sources and levels on performance and bioavailability of calcium and phosphorus in weaning piglets.Experiment Ⅰ Effect of Calcium Sources on Growth Performance and Calcium and Phosphorus Availability in SD RatsSingle factorial trial arrangement was performed in this study. Forty male SD rats aged25days (ADG:80±5g), were allocated to four diets involving1basal and3treatment groups, each for10replicate cages with one rat per cage. Basal diet Ca-unsupplemented (Ca level0.13%), three treatment diets (Ca level0.50%) were designed by adding different ratio of calcium carbonate, calcium citrate or calcium formate to basal diet at the expense of corn starch. The whole trial lasted for35d. Digestibility trial was conducted from25to28d of experiment using the total collection method. During the digestibility experiment six rats from each treatment were housed in metabolism cage (one rat/cage) for faeces collection.The results showed that:1During the initial two-week period, rats offered the diet supplemented the calcium citrate had higher ADG than rats fed the diet supplemented the calcium formate (P<0.05); ADG、ADFI and F/G no significant difference were observed among four groups rats in the final three weeks (P>0.05); Additionally, for the overall experiment period, calcium formate significant reduced ADG and feed conversion rate of the rats (P<0.05).2Serum Ca level was increased when calcium carbonate was included in the diet (P<0.05); however, reduced serum P level (P<0.05). Rats fed the diet supplemented the calcium citrate had lower serum AKP level than rats fed the other diets; however, serum1,25-(OH)2D3and CT no significant difference were observed among four groups rats (P>0.05).3Fresh Femoral weight, femoral strength, ash, Ca and P content of rats supplemented calcium citrate were higher than the rats fed other diets (P<0.05).4Calcium citrate and calcium formate group of Ca utilization were9.05%and8.06%higher than the calcium carbonate, respectively, but no significant difference, however, significantly higher than calcium carbonate group (P>0.05), each group had no significant differences between phosphorus utilization rate (P<0.05); Diet treatment no significant effect were observed on phosphorus availability in rats.Experiment2Effect of Calcium Sources and Level on Growth Performance and Calcium and Phosphorus Availability in Weaning PigletsA total of90LY (Landrace×Yorkshire) weaning piglets were assigned to2×8factorial arrangement. The two calcium sources were calcium carbonate and calcium citrate; Eight dietary calcium levels were0.37%,0.50%,0.60%,0.70%,0.80%,0.90%,1.00%and1.10%. Each treatment consisted of3replicate pens of2piglets. Additionally,6piglets randomized were assigned to calcium carbonate and calcium citrate0.8%treatment groups with3piglets each group. Digestibility trial was conducted from29to32d of experiment using the total collection method. The whole trial lasted for32d.The results showed that:1During whole experiment, no significant difference was observed on ADG, ADFI and F/G in piglets (P>0.05) from calcium sources or interactions between calcium sources and calcium levels. There was a quadratic response of ADG to increasing calcium levels:y=-367.63x2+504.94x+240.92, R2=0.847(P<0.05), with the optimum dietary calcium level of0.6%.2Calcium citrate had significantly higher calcium apparent digestibility than calcium carbonate in piglets (P<0.05). High dietary Ca levels increased P excretion and reduced P digestibility (P<0.05). The piglets fed the diets containing range0.37to0.80dietary Ca had higher Ca, P apparent digestibility than the piglets fed the diets containing high dietary calcium (P<0.05). Diet treatment no significant effect were observed on phosphorus availability in piglets(P>0.05).In conclusions, these results demonstrated that:The rats fed the diet included the calcium citrate increased the growth rate during the initial two-week period and femoral strength; however, ADG of the rats fed the diet supplemented calcium formate were reduced during the whole experiment. Calcium citrate is a good calcium source with higher bioavailability than calcium carbonate for weaning piglets. The piglets fed0.6%calcium grew better, regardless of dietary calcium source.