Cholecalciferol Supplementation in Heifer Diets Increases Beef Vitamin D Concentration and Improves Beef Tenderness

This study investigated the effects of cholecalciferol (vitamin D₃) supplementation on beef vitamin D concentration, beef tenderness and sensory evaluation. Thirty continental heifers were blocked on the basis of live weight and age and randomly allocated to one of three dietary treatments; (T1) basal + 0 IU of vitamin D₃; (T2) basal + 2000 IU of vitamin D₃ and (T3) basal + 4000 IU of vitamin D₃. Dietary treatments were offered for the final 28 days of an 80 day intensive finishing period. The basal diet consisted of a standard ad-libitum finishing regime of concentrates and forage (straw) offered at a ratio of 90:10. Animal growth was recorded weekly and individual dry matter intakes were recorded using Calan Broadbent Controlled feeding system. Blood samples were taken prior to slaughter for blood serum 25-OH-D₃concentration. Longissimus dorsi (LD) muscles were excised 10 days post slaughter for D₃ analysis carried out by analytical High Performance Liquid Chromatography. Data was analysed using mixed model ANOVA in SAS. Increasing dietary D₃ resulted in a linear response (P<0.05) in systemic 25-OH-D₃ blood concentrations ((T1) 88.63 vs (T2) 132.52 vs (T3) 165.45 n/mol/L sem 10.692)). Similarly, D₃ (P<0.05) content of LD beef also showed a linear response to dietary D₃ inclusion. Heifers fed 4000 IU of vitamin D₃, had higher LT cholecalciferol and 25-hydroxyvitamin D₃ activity, compared with those fed 0 IU of vitamin D₃ and 2000 IU of vitamin D₃. Indeed, D₃ content in the highest inclusion treatment (T3), showed 33% enhanced D₃ content compared to (T2) and 72% from (T1), ((T1) 0.019 vs (T2) 0.045 vs (T3) 0.067 µg/100g sem 0.0240)). Heifers offered 4000 IU of vitamin D₃ diet had a decreased Spinalis dorsi (SD) Warner Bratzler shear force (WBSF) value (P < 0.05) in 14 day old steaks, compared to other dietary treatments. Heifers offered the 2000 IU and the 4000 IU of vitamin D₃ also had a decreased (P < 0.05) WBSF values compared to the 0 IU of vitamin D₃ treatment. Mean sensory score parameters including appearance, odour, texture, flavour, overall acceptance and off flavour were not affected (P > 0.05) by dietary treatments. In conclusion results indicate that D₃ content of beef can be successfully enhanced through short term dietary supplementation and biofortification of beef may be potential food based strategy for increasing human vitamin D dietary intake.