Different beta 1 and 2 adrenergic receptors agonists might have various biological and physiological effects on fish species. An experiment was designed to study the effects of feeding ractopamine, terbutaline and metaproterenol; as beta1, beta2 and less selective beta2 adrenergic receptor agonists, respectively; on body weight gain, feed conversion rate, concentration of biochemical parameters...

Forty crossbred barrows (average initial weight, 66.4 kg) were utilized to determine the effects of ractopamine (a phenethanolamine/beta adrenergic agonist) on protein accretion and synthesis, activities of cathepsins B, H, L and calcium-dependent proteinase and nucleic acid content of semitendinosus muscle (ST). All pigs were offered a 16% protein, mineral and vitamin fortified corn-soybean me...

A total of 54 finishing barrows (initial BW = 99.8 ± 5.1 kg; PIC C22 × 337) reared in individual pens were allotted to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of treatments with 2 levels of ractopamine (0 and 7.4 mg/kg) and 3 levels of dietary energy (high, 3,537; medium, 3,369; and low, 3,317 kcal of ME/kg) to determine the effects of dietary ractopamine and various energy l...

The effect of dietary ractopamine and protein level on growth performance, individual muscle weight and carcass composition of finishing pigs were evaluated in two experiments. Twelve barrows and 12 gilts (Exp. 1) and 32 barrows (Exp. 2) with an average initial weight of 64 kg were penned individually and offered ractopamine at 0 or 20 ppm in diets containing 13 or 17% CP in 2 x 2 factorial exp...

Six trials involving 888 pigs (Study 1) and three trials involving 360 pigs (Study 2) were conducted at various geographical locations in the U.S. and Canada to evaluate the effect of ractopamine hydrochloride on the performance and carcass characteristics of finishing swine. All trials were conducted using a randomized complete block design. Trial data were pooled within study for statistical ...

Two experiments were completed to determine the effects of diet mix uniformity and ractopamine HCl on finishing pig performance. In Exp. 1, a total of 200 pigs (BW = 90 kg) were used in a 33-d growth assay arranged in a randomized complete block design with 5 pigs/pen and 8 pens/treatment. Treatments were a corn-soybean meal-based control diet mixed for 360 s or the mixed control diet with 10 m...

An 8-wk study of the effects of CLA, rendered animal fats, and ractopamine, and their interactive effects on growth, fatty acid composition, and carcass quality of genetically lean pigs was conducted. Gilts (n = 228; initial BW of 59.1 kg) were assigned to a 2 x 2 x 3 factorial arrangement consisting of CLA, ractopamine, and fat treatments. The CLA treatment consisted of 1% CLA oil (CLA-60) or ...

A monoclonal antibody-based immunoaffinity column (RAC-IAC) was developed as a cleanup method for the determination of ractopamine and ractopamine glucuronides. [14C]Ractopamine (5 microg) and [14C]ractopamine glucuronides (5 microg) were fortified into 10 mL cattle urine, and loaded onto an RAC-IAC (5 mg IgG/mL) column. The column was washed and the bound analytes were eluted. In the initial l...

A total of 480 pigs (PIC 327 × 1050; initially 107.4 lb) were used to determine the interactive effects of supplemental Cu, Zn, and Ractopamine HCl on finishing pig growth performance, carcass characteristics, and antimicrobial susceptibility of enteric bacteria. Dietary treatments were arranged in a 2 × 2 × 2 factorial with main effects of added copper sulfate (CuSO4; 0 vs. 125 ppm Cu), added ...

An experiment using 264 crossbred barrows was conducted to examine the interaction between space allocation and dietary ractopamine addition on pig performance and carcass characteristics using a 2 x 2 factorial arrangement of treatments. Treatments were 0.55 (19 pigs per pen) or 0.74 (14 pigs per pen) m2/pig from start (29.7 +/- 0.1 kg BW) to slaughter (108 kg BW) in a fully slatted facility a...