الفهرس 
CoverOnly 14 pages are availabe for public view
 |  | from | 82 |  |  |
| | | from | 82 | | |
Abstract
This study was directed to assess the expression of some genes which are implicated in energy metabolism and mitochondrial biogenesis such as avian adenine nucleotide translocator (avANT), ATPase (ATP5G1 and ATP5E), peroxisome proliferator-activated receptor-γ (PPARγ) and avian PPARγ coactivator-1α (avPGC-1α), in addition to some of growth related genes such as MyoD, MyoG and MSTN in breast muscle of Cobb broilers. Tow studies were conducted; the first one during pre-hatching stage at day 12th, 15th and 19th and ten eggs were taken at each period (day 12th, 15th and 19th) then the developed embryonic breast muscle was taken and stored at -80°C until used.
The second study at post-hatch at day 21th and 35th; One hundred- and fifty-day-old male broilers (Cobb 500) chicks were reared in this study. At one old day, the chicks were divided into 3 groups according to their body weight; large BW group, medium BW group and small BW group. The chicks were raised on floor, given unlimited amounts of feed and water and received all vaccines. Birds were individually weighed at 0, 7, 14, 21, 28 days, and at the end of the rearing period (35 days). Also weekly feed consumption (FC), total feed intake (TFI) to determine performance indices such as the total body weight gain (TBWG), feed consumption (FC), feed efficiency (FE) and feed conversion ratio (FCR).samples from pectoral muscle were collected at D-21and D-35 (five birds from each group) and stored at -80°C until used.
The total RNA was extracted from snap-frozen tissues from pectoral muscle of egg embryos in pre-hatch study as well as male broilers with small and large body weight in post-hatch study. Total RNA was reverse transcribed using random primers followed by real-time reverse transcription-PCR.
The mRNA expression of mitochondrial protein genes was different than growth related genes at embryonic stage at E-12, E-15 and E-19 as well as at post hatching stage at day 21th and 35th. ANT gene was significantly expressed pre-hatching with highest level at E-15 , while it showed insignificant increase of expression in small body weight relative to large body weight at day 21 and 35 post-hatching. The expression level of ATP5G1and ATP5E not detected pre-hatching. On the other hand, they showed no difference between high and low body weight at day 21, while at day 35; ATP5G1 was higher in small body weight compared to large body weight in contrast to ATP5E that was lower in small BW relative to large BW.
The avPGC-1α was significantly expressed at E-12, E-15 and E-19, while PPARγ was not detected pre-hatching. avPGC-1α and PPARγ at day 21 showed significantl up-regulation in small BW if compared with large BW, while at day 35 avPGC-1α and PPARγ showed no differences in their expression between small BW and large BW broilers.
With considering growth related genes; MyoD and MyoG gene were expressed with a little amount pre-hatching, but most prominent at E-12. MyoD was higher in large BW compared to small BW broilers significantly at day 21 and insignificantly at day 35. MyoG was not detected at day 21, while was insignificantly higher in small BW than large BW at day 35. MSTN was not detected pre-hatching, while it was up-regulated in small BW compared to large BW birds at day 21 and 35.
These outcomes show that there are variations in the expression of mRNA encoding for mitochondrial transcription factors and proteins as well as growth related genes in breast muscle between small and large BW male broilers. The changes that were noticed may too reveal inherent metabolic and gene control differences in breast muscle.