The effects of dietary lipid and rumen protected Capsicum oleoresin on plasma glucose and insulin kinetics, and feed efficiency in finishing beef cattle
This research was conducted to evaluate the effects of dietary lipids and rumen protected Capsicum oleoresin (i.e. capsaicin) on finishing beef cattle feedlot performance, DMI, carcass characteristics, circulating blood metabolites and acute phase proteins, and insulin sensitivity in response to an intravenous glucose tolerance test. In the first study, the experimental design was a 22+1 factorial arrangement including: no additive (control; CON); a low or high dose of rumen protected Capsicum oleoresin (CapsXL; 77 mg/d for RPLO and 250 mg/d for RPHI); or a low or high dose of Capsicum oleoresin that was rumen protected to a greater extent (Nexulin; 100 mg/d for HPLO or 322 mg/d for HPHI). The -LO and -HI doses were formulated to provide equal total ingested Capsicum oleoresin for both supplements (15.5 and 49.9 mg/day, respectively). A total of 450 steers were included, with 69 days-on-feed. All steers received the same basal diet of (dry matter basis) barley grain (86.2%), barley silage (6.0%), canola meal (6.2%), and a vitamin and mineral supplement (1.6%). Including rumen protected Capsicum in finishing steer diet did not affect their DMI, growth, or carcass weight. However, carcass yield grade, quality grade, and marbling score were decreased (P ≤ 0.032) by increasing the dose of Capsicum. In the second study, rumen protected Capsicum product CapsXL was fed to 12 Hereford Simmental beef heifers arranged in a 4 4 Latin square design balanced for carry-over effects, with 3 replications and 28-day period length. Treatments followed a 2 2 factorial design utilizing a barley-based high-grain diet that included Capsicum oleoresin at 0 (C-) or 77 (C+) mg/d and palmitic acid to increase dietary ether extract concentrations from 3.46% (P-) to 7.63% (P+) on a DM basis. The base diet consisted of barley silage (6.93%; DM basis), barley grain (82.12%), mineral (5.83%), urea (0.32%), and beet pulp (5.8%). Palmitic acid replaced beet pulp in the diet, which allowed similar forage:concentrate ratio and starch concentrations among diets. Apparent total tract digestibility, DMI, baseline fed-state blood sampling, and an intravenous glucose tolerance test and corresponding muscle biopsies to assess muscle glycogen concentrations were included in data collection in the second study. Palmitic acid increased peak insulin (P = 0.003), insulin positive incremental area under the curve, the total area under the curve for insulin (I-AUC and AUC, respectively; P ≤ 0.003), insulin clearance rate (P ≤ 0.015), and decreased both the maximum concentration of glucose reached and the maximum change in glucose concentration observed (P ≤ 0.029) during the IVGTT. Capsicum prevented an increase in insulin concentration prior to the IVGTT when fed with palmitic acid (Capsicum palmitic acid interaction, P = 0.017). Including palmitic acid to finishing diets increased insulin resistance, but Capsicum may help moderate insulin concentrations. However, Capsicum elicited no effects during IVGTT in the second study (P ≥ 0.15). As a high dose of Capsicum in the first study may negatively affect quality grades and marbling score, the lack of effect of Capsicum in the second study suggest that its effects in finishing beef rations may be dose dependent.
Insulin, Resistance, Cattle, Palmitic Acid
Master of Science (M.Sc.)
Animal and Poultry Science