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 .
Requirement for digestible calcium by 25 to 50 kg pigs at different dietary concentrations of phosphorus as indicated by growth performance, bone ash concentration, and calcium and phosphorus balances.
Two experiments were conducted to determine the requirement for st and ardized total tract digestible ( STTD ) Ca by 25 to 50 kg pigs at different concentrations of STTD P. Twenty corn-soybean meal based diets were formulated with diets containing 4 concentrations of STTD P ( 0.15 , 0.31 , 0.39 , or 0.47 % ) and 5 concentrations of STTD Ca ( 0.13 , 0.27 , 0.42 , 0.57 , or 0.72 % ) . Diets were mixed in 1 batch and were used in both experiments . In Exp . 1 , 240 pigs ( initial average BW : 24.70 ± 1.27 kg ) were r and omly allotted to the 20 diets in 6 blocks with 1 pen per diet in each block using a 4 × 5 factorial design . There was 1 gilt and 1 barrow in each pen . At the conclusion of the 28 d experiment , all barrows were euthanized and the right femur was collected . Results indicated that there were interactions ( < 0.001 ) between concentration of STTD Ca and concentration of STTD P in diets for ADG , G : F , and bone ash . The predicted maximum ADG at STTD P concentrations of 0.15 , 0.31 , 0.39 , and 0.47 % were 0.76 , 0.87 , 0.90 , and 0.92 kg at STTD Ca concentrations of 0.12 , 0.36 , 0.47 , and 0.59 % , respectively , which correspond to STTD Ca : STTD P ratios of 0.80:1 , 1.16:1 , 1.21:1 , and 1.26:1 . The predicted maximum G : F ratio at the 4 STTD P concentrations were 0.43 , 0.46 , 0.48 , and 0.50 kg/kg at STTD Ca concentrations of 0.09 , 0.38 , 0.52 , and 0.67 % , respectively , and these values correspond to STTD Ca : STTD P ratios of 0.60:1 , 1.23:1 , 1.33:1 , and 1.43:1 . The predicted maximum bone ash at the 4 STTD P concentrations were 14.5 , 21.0 , 23.1 , and 24.5 g at STTD Ca concentrations of 0.41 , 0.56 , 0.64 , and 0.72 % , respectively , which correspond to STTD Ca : STTD P ratios of 2.73:1 , 1.81:1 , 1.64:1 , and 1.53:1 . In Exp . 2 , 120 pigs ( initial average BW : 29.45 ± 2.15 kg ) were placed in metabolism crates and r and omly allotted to the 20 diets in 6 blocks with 1 pig per diet in each block . Fecal and urine sample s were collected . Results indicated that the predicted maximum retention of Ca in the body at STTD P concentrations of 0.15 , 0.31 , 0.39 , and 0.47 % were 4.7 , 7.1 , 8.6 , and 10.2 g/d at STTD Ca concentrations of 0.77 , 0.96 , 1.06 , and 1.15 % , respectively , which correspond to STTD Ca : STTD P ratios of 5.13:1 , 3.10:1 , 2.72:1 , and 2.45:1 . These observations indicate that if STTD P meets or exceeds the requirement , the STTD Ca : STTD P ratio needed to maximize ADG and G : F by 25 to 50 kg pigs is between 1.16:1 and 1.43:1 . However , a greater ratio may be needed to maximize bone ash or Ca retention
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 .