These outcomes advance the current underst and ing of Ca digestibility and utilisation , and should contribute towards establishing requirements for digestible Ca .
Consequently , pig diets will be more correctly formulated if digestible Ca values are used in estimating requirements for Ca
Ca digestibility and utilisation in growing pigs are not well understood , and are usually neglected in diet formulation .
This has implication s not only for the accurate determination of its requirements but also for its interactions with other nutrients .
A systematic review and meta- analysis ( meta-regression ) of published trials was carried out to quantify factors affecting Ca absorption and utilisation , and to derive an estimate of Ca endogenous excretion .
Concentration of dietary calcium supplied by calcium carbonate does not affect the apparent total tract digestibility of calcium, but decreases digestibility of phosphorus by growing pigs.
A regional experiment was conducted to test the hypothesis that the concentration of dietary Ca does not affect the digestibility of Ca or P in diets fed to growing pigs .  Six diets based on corn , potato protein isolate , cornstarch , and soybean oil were formulated . All diets also contained monosodium phosphate , crystalline AA , salt , and a vitamin-micromineral premix . The only difference among the diets was that varying concentrations of calcium carbonate were used to create diets containing 0.33 , 0.46 , 0.51 , 0.67 , 0.92 , and 1.04 % Ca . All diets contained between 0.40 and 0.43 % P. Six universities participated in the experiment and each university contributed 2 replicates to the experiment for a total of 12 replicates ( initial BW : 23.1 ± 4.4 kg ) . Pigs were placed in metabolism cages that allowed total , but separate , collection of feces and urine from the pigs . Pigs within each replicate were r and omly allotted to the 6 diets and fed experimental diets for 14 d with urine and feces being collected over a 5-d period . Diets , feces , and urine sample s were analyzed for Ca and P , and the daily balance , the apparent total tract digestibility ( ATTD ) , and the retention of Ca and P were calculated . Results indicated that intake , fecal excretion , and urinary excretion of Ca increased ( linear , P<0.05 ) as dietary Ca concentration increased . The daily intake of P was not affected by the dietary concentration of Ca , but fecal excretion of P increased ( linear , P<0.05 ) as dietary Ca concentrations increased . In contrast , urinary P output was decreased ( linear , P<0.05 ) as dietary Ca increased . The retention of Ca increased ( linear , P<0.05 ) from 1.73 to 4.60 g/d , whereas the retention of P decreased ( linear , P<0.05 ) from 1.98 to 1.77 g/d as dietary Ca concentrations increased . However , if calculated as a percentage of intake , both Ca and P retention were decreased ( linear , P<0.05 ) as dietary Ca concentration increased ( from 55.4 to 46.1 % and from 48.4 to 43.5 % , respectively ) . The ATTD of Ca was not affected by the dietary concentration of Ca , but the ATTD of P was decreased ( linear , P<0.05 ) from 56.9 to 46.2 % as dietary Ca concentration increased . It is concluded that the dietary concentration of Ca does not affect the ATTD of Ca in calcium carbonate , but increased concentrations of dietary Ca may decrease the ATTD of P in diets based on corn , potato protein isolate , and monosodium phosphate
These outcomes advance the current underst and ing of Ca digestibility and utilisation , and should contribute towards establishing requirements for digestible Ca .
Consequently , pig diets will be more correctly formulated if digestible Ca values are used in estimating requirements for Ca
Ca digestibility and utilisation in growing pigs are not well understood , and are usually neglected in diet formulation .
This has implication s not only for the accurate determination of its requirements but also for its interactions with other nutrients .
A systematic review and meta- analysis ( meta-regression ) of published trials was carried out to quantify factors affecting Ca absorption and utilisation , and to derive an estimate of Ca endogenous excretion .