Short communication: commercial diets for pigs in the United States contain more calcium than formulated.

Data from Europe indicate that commercial diets for pigs and poultry contain significantly more Ca than formulated. Therefore, a survey of commercial pig diets used in the United States was conducted to test the hypothesis that the analyzed concentrations of total Ca and total P in commercial pig diets in the United States are not greater than formulated values. A total of 103 diet samples from the commercial swine industry in the United States were collected between 2019 and 2021. Diet samples were provided by feed mills, feed companies, or swine farms located in major swine-producing states in the United States including NC, TN, IA, IN, KS, MN, NE, and IL. Diets were formulated for nursery pigs, growing-finishing pigs, or sows. Each company provided formulated values for total Ca and P in all samples. Samples were sent to the University of Illinois where they were ground and analyzed for Ca and P by inductively coupled plasma-optical emission spectrometry. The formulated values for Ca and P were regressed against analyzed values, and the intercept was considered the estimated under- or over-supply of each mineral. Results indicated that there was an average of 0.19 percentage units more Ca (model; P < 0.001) in the diets than formulated, whereas, for total P, the average oversupply was only 0.06 percentage units (model; P < 0.001). In conclusion, diets used in the U.S. swine industry contain more total Ca than formulated, whereas total P is close to formulated values, which indicates that greater importance is given to P than to Ca in formulation. However, the current data indicate that more attention should be given to the actual concentration of Ca in all Ca-containing feed ingredients to avoid Ca oversupply and its detrimental effect on P digestibility and growth performance of pigs fed diets that do not contain excess P.

Calcium is often oversupplied in pig diets because limestone, the main source of Ca in pig diets, is an inexpensive feed ingredient and is often used as a carrier in premixes or a diluent in feed ingredients. However, excess Ca may be detrimental to P digestibility and pig growth performance. It was recently reported that commercial pig and poultry diets sold in Europe contain significantly more Ca than formulated, but it is not known if the Ca concentrations in commercial pig diets in the United States also contain more Ca than formulated. Therefore, a survey of commercial diets from the United States was conducted to compare analyzed and formulated values for Ca. A total of 103 diets were collected from feed mills, feed companies, or swine integrators in the United States between 2019 and 2021. Samples were analyzed for total Ca and total P. Results from the regression model used to evaluate the data indicated that diets on average contained 0.19 percentage units more total Ca and 0.06 percentage units more total P than expected. Thus, more attention needs to be paid to the inclusion of Ca in pig diets to avoid Ca oversupply and the negative effects of Ca on pig growth performance.