effect of anabolic implants on intramuscular lipid deposition in finished beef cattle

• Published in: Journal of animal science 2007-02, Vol.85 (2), p.430-440
• Main Authors: Smith, K.R, Duckett, S.K, Azain, M.J, Sonon, R.N. Jr, Pringle, T.D
• Format: Article
• Language: English
• Subjects: acetyl-CoA carboxylase; Actins - analysis; Actins - biosynthesis; adipocytes; adipose tissue; Adipose Tissue - diagnostic imaging; Adipose Tissue - enzymology; Adipose Tissue - physiology; Anabolic Agents - administration & dosage; Anabolic Agents - pharmacology; anabolic steroids; animal performance; Animal productions; Animals; Beef; beef cattle; Biological and medical sciences; body weight; carcass characteristics; carcass quality; carcass weight; Cattle - metabolism; Cellular biology; Contraceptive Agents - administration & dosage; Contraceptive Agents - pharmacology; diameter; dressing percentage; Drug Implants; Enzymes; Enzymes - drug effects; Enzymes - metabolism; Estradiol - administration & dosage; Estradiol - analogs & derivatives; Estradiol - pharmacology; fatty acid composition; Female; Food industries; Fundamental and applied biological sciences. Psychology; gene expression; Gene Expression - drug effects; lipid deposition; lipoprotein lipase; liveweight gain; Male; marbling; Meat - standards; Meat and meat product industries; messenger RNA; Oils & fats; Random Allocation; Ribonucleic acid; RNA; steaks; stearoyl-CoA desaturase; subcutaneous fat; Terrestrial animal productions; Trenbolone Acetate - administration & dosage; Trenbolone Acetate - analogs & derivatives; Trenbolone Acetate - pharmacology; Ultrasonography; Vertebrates
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jas.2006-280

Two experiments were conducted to determine the effects 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; 411 kg 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 rib) 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 0.10) between treatments. Percentage of SC adipocytes was greater at larger diameters ( > 150 μm), whereas the majority of i.m. adipocytes were at small to middle diameters (50 to 150 μm). The number of i.m. adipocytes per gram of tissue was greater (P < 0.05) for SP than C and also were greater (P < 0.05) than the number of s.c. adipocytes in SP heifers. In experiment 2, adipocytes per gram of tissue tended to be greater (P = 0.07) for SP than C and were greater (P < 0.01) for i.m. than s.c. In experiment 1, average cell diameter and volume did not differ (P > 0.10) between treatments and tissues, but in experiment 2 both cellularity traits were greater (P < 0.01) for s.c. than for i.m.. Implanting did not alter mRNA expression of ACC, SCD, or LPL in i.m. adipose tissue. This study shows that anabolic implants do not appear to have direct