An experiment was conducted to evaluate the effects of dietary boron (B) on growth performance, bone mechanical properties, and calcium, phosphorous, and nitrogen metabolism in pigs. Thirty-six barrows were weaned at approximately 21 days of age and were randomly assigned to one of the following treatments: 1) control diet, 2) 5 mg B/kg diet, or 3) 15 mg B/kg diet. Barrows remained on their respective experiment diets throughout the nursery (35 days) and growing (30 days) of production. Following the 30 day growing period, 8 barrows per treatment were transferred to stainless steel metabolism crates. Barrows had an adjustment period of 7 days, followed by 7-day total collection of urine and feces. At the end of the collection period, barrows were harvested and femurs fibulas were obtained for assessment of bone mechanical properties.
During the nursery phase, gain and feed intake were increased by 5 and 15 mg supplemental B/kg diet. During the growing phase, gain and feed intake were increased by 15 mg supplemental B/kg diet. Barrows fed 5 mg supplemental B/kg diet had decreased serum concentrations of triiodothyronine during the growing phase. Supplementation of 5 mg B/kg diet decreased urinary calcium and increased urinary phosphorous excretion. Apparent absorption and retention of calcium, phosphorous and nitrogen were not affected by dietary B. Boron did not affect bone ash percentage, but supplementation of 15 mg B/kg diet increased bone phosphorous and increased bone stress of the femur and ultimate shear force of the fibula. Results of this study showed that B supplementation of pig diets can increase growth and bone strength, without greatly affecting calcium and phosphorous metabolism.