The effect of supplemental manganese in broiler diets on abdominal fat deposition and meat quality

An experiment was conducted using a total of 288 day-old Arbor Acres male broilers to study the effect of supplemental manganese (Mn) levels on carcass traits, meat quality and relative enzyme activities in the abdominal fat and meat. Birds were randomly allotted by body weight to one of six treatments (eight replicate cages of six chicks per cage) in a completely randomized design. Broilers were fed on Mn-unsupplemented maize–soybean meal basal diets containing 9.5 g Ca/kg and 22.74 mg Mn/kg for the first phase of 21days and adjusted to 8.8 g Ca/kg and 18.86 mg Mn/kg for a second phase of 21days (42days total), or fed basal diets supplemented with 100, 200, 300, 400 or 500 mg/kg Mn as Mn sulphate (MnSO4·H2O) for the duration of the 42 days. The supplemental Mn level had no effect (P>0.05) on the dressing percentage, the percentage of breast or leg muscles, water-holding capacity, L* value, a* value, shear force, and intramuscular fat in breast and leg muscles. Additionally, the supplemental Mn level did not influence (P>0.05) pH values in leg muscles, b* value, malondialdehyde (MDA) content and Mn-containing superoxide dismutase (MnSOD) activity in breast muscle, or malate dehydrogenase (MDH) activity and hormone sensitive lipase (HSL) activity in abdominal fat. However, Mn did influence the content of abdominal fat (P<0.01), pH in breast muscle (P<0.05), b* value and MDA content in leg muscle (P<0.05). Furthermore, Mn affected lipoprotein lipase (LPL) activities in abdominal fat (P<0.001) and MnSOD activities in leg muscles (P<0.05). Abdominal fat content and LPL activities in the abdominal fat decreased quadraticly (P<0.01) as dietary Mn level increased. The pH in breast muscle decreased linearly (P<0.01) with increasing Mn levels. As dietary Mn level increased, MDA content and MnSOD activities in leg muscle decreased and increased quadraticly (P<0.05), respectively. The results from the study indicate that the addition of 100 mg Mn/kg to broiler diets might decrease the abdominal fat content by reducing LPL activity in abdominal fat, and decrease MDA content in leg muscle by increasing MnSOD activity in leg muscle.