Interpretive Summary: Using digestible calcium to formulate the diets of growing-finishing pigs is an effective replacement for total calcium
By: Anne Kamiya, MS
Currently, total calcium (Ca) values determine the dietary needs of pigs fed mixed feed diets. Using the ratio of standardized total tract digestible (STTD) Ca and STTD phosphorus (P) may be a more accurate method for calculations, according to the National Research Council (NRC). The authors of this recent Journal of Animal Science study compared the carcass characteristics and growth performance of growing-finishing pigs when feed requirements were determined based on STTD Ca versus total Ca. They also included STTD Ca and STTD phosphorus P ratios.
A total of 160 pigs were monitored from 11 to 130 kilograms (kg). Pigs were fed a 5-phase diet determined by their weight (with phase 2 starting at 25 kg, phase 3 starting at 50 kg, phase 4 staring at 75 kg and phase 5 starting at 100 kg). Diets were corn-soybean meal based and minimum nutrient requirements were calculated from either total Ca or STTD Ca. Each diet had versions with or without added dietary phytase, a microbial enzyme that breaks down antinutrients in plant-based feed. Carcass characteristics and blood samples were evaluated at the end of the study.
Results indicated no differences between the growth performance of pigs fed diets with feed requirements calculated from STTD Ca versus total Ca. Growth performance and carcass characteristics were also not impacted by the inclusion of microbial phytase, however, bone resorption was negatively impacted by pigs fed diets without phytase.
Overall, the results of this study suggest that the dietary needs of pigs can be calculated using digestible Ca (STTD Ca to STTD P ratios) instead of total Ca, with no detrimental impact on carcass characteristics and growth performance. More studies into the impacts of phytase on bone health and bone resorption in growing-finishing pigs may be warranted.
The original article, Formulating diets based on digestible calcium instead of total calcium does not affect growth performance or carcass characteristics, but microbial phytase ameliorates bone resorption caused by low calcium in diets fed to pigs from 11 to 130 kg, is available on the Journal of Animal Science website.