Effect Of Manganese On Carcass Traits, Meat Quality Of Broilers And Modes Of Action

The effects of dietary Mn source and level on growth performance, carcass traits, meat quality, relative enzyme activities in muscle and abdominal fat, and MnSOD gene expression in muscle mitochondria was investigated from the following three aspects in this paper, so as to discuss how Mn affects carcass traits and meat quality of broilers and its modes of action from.1. An experiment was conducted using a total of 288 day-old Arbor Acres (AA) male broilers to study the effect of supplemental manganese (Mn) levels (0, 100, 200, 300, 400 or 500 mg/kg ) on growth performance, carcass traits, meat quality and relative enzyme activities in abdominal adipose tissue of the broilers. The addition of 100, 200, or 300 mg/kg Mn from Mn sulfate did result in decreases in abdominal fat percentage (P < 0.03) and lipoprotein lipase (LPL) activity in abdominal fat (P < 0.08). Broilers fed on the 100 mg/kg Mn had a higher pH (P < 0.05) in breast muscle than those on the other Mn treatments. The addition of 100, 200, 300 or 500 mg/kg Mn decreased MDA content (P < 0.06) and increased the activity of MnSOD in thigh muscle (P < 0.08). The results from this study indicate that the addition of Mn to broiler diets might decrease the percentage of abdominal fat by reducing LPL activity in abdominal fat, so as to improve carcass quality, and might decrease MDA content in thigh muscle by increasing MnSOD activity in thigh muscle, so as to improve meat quality.2. An experiment was conducted using a total of 336 day-old AA commercial male broilers to investigate the effects of dietary Mn source (Mn sulfate, Mn-AA A or Mn-AA B) on growth performance, carcass traits and relative enzyme activities in abdominal adipose tissue of the broilers. Birds fed diets supplemented with Mn from Mn sources had lower (P < 0.10) percentages of abdominal fat, LPL and MDH activities in abdominal fat and higher HSL activities in abdominal fat than those fed the control diet. Birds fed diets supplemented with Mn from Mn-AA A or Mn-AA B had lower (P < 0.05) LPL activities in abdominal fat than those fed diets supplemented with Mn sulfate. Birds fed diets supplemented with Mn from Mn sources had lower (P < 0.03) MDA content in thigh muscle and higher (P < 0.02) MnSOD activities and MnSOD mRNA level in breast and thigh muscle. Birds fed diets supplemented with Mn from Mn-AA A had higher (P < 0.02) MnSOD mRNA level in thigh muscle mitochondria than those fed diets supplemented with Mn from Mn sulfate. The results indicate that organic Mn with the moderate complex strength was more available than inorganic Mn source to decrease LPL activity in abdominal fat of broilers, and dietary Mn might reduce abdominal adipose deposition by decreasing LPL and MDH activities or increasing HSL activity in abdominal adipose tissue. The results also indicate that dietary Mn significantly affected muscle MnSOD gene expression pretranslationally. Furthermore, the decrease in muscle MDA content due to Mn addition might be related to the increase in MnSOD mRNA level in mucle mitochondria.3. An experiment was conducted in a completely randomized design involving a 3X4 factorial arrangement of treatments with purified LPL in order to determine whether Mn could directly inhibit the enzyme'. Three Mn sources (Mn sulfate, Mn-AA A and Mn-AA B) and four supplemental Mn levels (0,0.02, 0.04, and 0.08 mg/kg) were used. Mn as Mn sulfate, Mn-AA A or Mn-AA B was added to the tris buffer solution (0.01M, pH8.0, sigma chemical) containing purified LPL. Subsequent steps followed LPL procedures in Experiment 1 and 2. Activity of the purified enzyme in its tris buffers were adjusted to be similar to its respective activity in the abdominal fat supernatants. The results showed that Mn source, level and source X 1evel interaction had no effect on purified LPL activities in vitro (P > 0. 58). This results indicate that Mn could not inhibit LPL activity in vitro.