two experiments were conducted to determine the effect of anabolic implants on performance,
changes in ultrasound measurements,
carcass quality,
cellularity of i.m. and s.c. adipose depots,
and mRNA expression of acetyl CoA carboxylase (ACC),
stearoyl CoA desaturase (SCD),
and lipoprotein lipase (LPL) in i.m. adipose tissue of finished beef cattle.
Angus heifers (experiment 1:n = 10;411kg of BW) and steers (experiment 2:n=18;279 kg of BW ) were randomly allotted as control (C) or implanted with Synovex-Plus (SP) at d 0 and midway through the finishing period.
The cattle were fed a high-concentrate diet and were weighed at approximately 28-d intervals.
Heifers and steers were finished for 108 and 133 d, respectively.
At slaughter,
a section of the LM (sixth to ninth rib) was removed,
and i.m. adipose tissue was dissected for mRNA analysis.
Subcutaneous and i.m adipose tissues also were collected for determination of cellularity.
At 48 h postmortem,
carcass data were collected,
and a steak (12th rip) was removed for analysis of lipid and fatty acid composition.
Body weight did not differ (P>0.10) between treatments until after reimplanting of the heifers (d 55) or steers (d 73).
Average daily gain was 36 and 16% faster (P< 0.01) for implanted heifers and steers,respectively, compared with their control counterparts.
Implanting resulted in larger (P>0.10) HCW and LM area for heifers and steers.
However,implanting did not affecte (P>0.01) dressing percent, fat thickness,percentage of KPH , yield grade, or marbling score.
Intramuscular lipid content and concentrations of major fatty acid did not differ (P>0.10) between Percentage of SC adipocytes was greater at larger diameters (>150 m),whereas the majority of i.m. adipocytes were at small to middle diameters (50 to 150 m).
The number of i.m. adipocytes per gram of tissue was greater (p