Effect of chromium picolinate and chromium propionate on glucose and insulin kinetics of growing barrows and on growth and carcass traits of growing-finishing barrows

Two experiments were conducted to determine the effects of dietary Cr tripi colinate (CrPic) or Cr propionate (CrProp) on growth, carcass traits, plasm a metabolites, glucose tolerance, and insulin sensitivity in pigs. In Exp. 1, 36 barrows (12 per treatment; initial and final BW were 20 and 38 kg) we re allotted to the following treatments: 1) corn-soybean meal basal diet (c ontrol), 2) as 1 + 200 ppb Cr as CrPic, or 3) as I + 200 ppb Cr as CrProp. Growth performance data were collected for 28 d, and then 23 pigs (seven, e ight, and eight pigs for treatments 1, 2, and 3, respectively) were fitted with jugular catheters and a glucose tolerance test (500 mg glucose/kg BW) and an insulin challenge test (0.1 IU of porcine insulin/kg BW) were conduc ted. Both CrPic and CrProp decreased (P < 0.05) ADG and ADFI but did not af fect gain:feed (P > 0.10). Fasting plasma glucose, total cholesterol, urea N, insulin, and high-density lipoprotein cholesterol:total cholesterol conc entrations were not affected (P > 0.10) by either Cr source. Pigs fed CrPic had lower (P < 0.02) fasting plasma NEFA concentrations than control pigs, but plasma NEFA concentrations of pigs fed CrProp were not affected (P > 0 .10). During the glucose tolerance test, glucose and insulin kinetics were not affected by treatment (P > 0.10). During the insulin challenge test, gl ucose clearance was increased (P < 0.01) in pigs fed CrProp but not affecte d (P > 0.10) in pigs fed CrPic. Glucose half-life was decreased (P < 0.03) in pigs fed CrPic or CrProp, but insulin kinetics were not affected (P > 0. 10). In Exp. 2, 48 barrows (four replicates of four pigs per replicate; ini tial and final BW were 23 and 115 kg) were allotted to the same dietary tre atments in a growing-finishing study. Average daily gain, ADFI, and gain:fe ed were not affected (P > 0.10) by treatments. Carcass length tended (P = 0 .10) to be greater in pigs fed CrPic than in pigs fed CrProp, but other car cass measurements were not affected (P > 0.10). Glucose kinetics from the i nsulin challenge test indicate that both CrPic and CrProp increase insulin sensitivity and that both Cr sources are bioavailable.