Effects of supplemental zinc and ractopamine on growth performance, carcass composition, and skeletal muscle synthesis and gene expression in finishing pigs.
Abstract
The potential of supplemental zinc from zinc oxide (ZnO) and Availa Zinc® (AZ) to enhance the ractopamine (RAC) response in finishing pigs was investigated. In the first study, feeding RAC increased ADG, G:F, hot carcass weight (HCW) loin muscle area (LMA), and dissected ham lean (DHL). Pigs fed AZ had 6.13% greater ADG and tended to have greater G:F than pigs fed ZnO. Feeding AZ partially mitigated the adverse effects of RAC on foot health. A second study was conducted to determine if a lower inclusion of supplemental zinc (25 ppm) could elicit a similar response to 50 ppm supplemental zinc during RAC feeding. Feeding RAC increased ADG, G:F, HCW, DHL, LMA, and carcass lean. Supplemental zinc from ZnO and AZ had no effect on overall growth performance and carcass composition. A third study investigated the effect of 50 ppm supplemental zinc from AZ and RAC on skeletal muscle gene and protein expression in finishing gilts. Feeding RAC increased expression of myosin heavy chain (MyHC) IIb and decreased expression of MyHC IIa in the longissimus dorsi (LD). Feeding RAC decreased expression of MyHC IIa in the semimembranosus (SMB). Feeding RAC increased phosphorylated (p-) AKT while feeding AZ increased p-AKT and p-S6 in the LD. Feeding RAC and AZ alone increased p-4E-BP1 in the LD while feeding RAC in combination with AZ increased p-4E-BP1 in the SMB. These studies demonstrate that zinc has the potential to enhance the RAC response potentially by acting through the mammalian target of rapamycin pathway, though the response is inconsistent. Work evaluating dietary iodine value (IV) was also conducted. Diet IV had no major impact on growth performance in either study. Gilts fed a diet high in saturated fatty acids (SFA) had firmer bellies and whiter fat than pigs fed diets high in unsaturated fatty acids (UFA). In a second study the relationship between fat depot FA was determined. Intake of PUFA had greater correlations with tissue PUFA than did intake and tissue concentration of SFA and MUFA. Additionally, tissue FA concentration more closely followed the intake of diet polyunsaturated FA than monounsaturated FA or SFA.
Degree
Ph.D.
Advisors
Richert, Purdue University.
Subject Area
Animal sciences
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