Calcitic seaweed (Lithothamnion calcareum) as an organic source of calcium in piglet feeding

Abstract

Context Lithothamnion calcareum is a calcitic seaweed (CS), rich in calcium (Ca) and other minerals, with potential for use in piglet feeding. Aim The aims were to compare L. Calcareum (CS) with calcitic limestone (CL) as a source of Ca for use in piglet feeding for effects on total tract digestibility and daily balance of Ca, growth performance and serum variables, and to assess solubility of Ca sources through in vitro testing. Methods In Expt 1, an availability assay was performed on 24 crossbred male piglets with initial average body weight (BW) of 15.17 ± 0.70 kg in a randomised complete block design with six replicates of four treatments and one piglet per experimental unit. The starter dietary treatments were: basal diet with minimal amount of Ca (0.068%); diet with low Ca (0.018%); and two diets containing either CL or CS to provide 0.82% total Ca. In Expt 2 (growth performance), 96 crossbred male piglets, with initial average BW of 6.01 ± 0.70 kg were assigned in a randomised complete block design with eight replicates of three treatments (CL, CL + CS, or CS) and four piglets per experimental unit, assessed over pre-starter phases I and II and the starter phase. Key results In Expt 1, Ca source did not influence (P > 0.05) apparent and true digestibility or daily balance and concentration of Ca in the piglets. In Expt 2, no significant differences (P > 0.05) existed for growth performance during the pre-starter I and II phases, although a trend (P ≤ 0.1) was evident for final BW, daily weight gain and feed conversion ratio (FCR) during the pre-starter II phase. Piglets fed CL showed a reduction in FCR during the starter phase (P = 0.02) and for the total period (P = 0.007). Final BW and daily weight gain did not differ between CL and CS diets during the starter phase or for the total period. No effect (P > 0.05) was observed of Ca source on Ca and phosphorus concentrations in serum. CS had a solubility 1.9 times higher than CL. Conclusion Piglet performance parameters were generally similar for diets including CS and CL as a source of Ca. Implications Based on the evaluation criteria used in these experiments, L. calcareum has potential to replace calcitic limestone as an alternative source of Ca.