EFFICACY OF CHROMIUM PICOLINATE AND CHROMIUM CHLORIDE AS POTENTIAL CARCASS MODIFIERS IN SWINE

We conducted two experiments to evaluate the effects of chromium picol inate and chromium chloride (CrCl3) on growth performance, carcass com position, percentages and accretion rates of carcass tissues and chemi cal components, and blood metabolites in pigs. In Exp. 1, 35 individua lly penned pigs were fed a fortified, corn-soybean meal basal diet (.9 5% lysine) supplemented with 0, 200, or 400 mu g/kg of Cr from chromiu m picolinate or 5,000 or 25,000 mu g/kg of Cr from CrCl3. Each diet wa s fed to seven pigs for 35 d (19.6 to 43.2 kg BW). Addition of 200 mu g/kg of Cr from chromium picolinate increased ADG (P < .07) and ADFI ( P < .03) but did not affect feed:gain ratio. Backfat measurements and longissimus muscle area were not affected by either source of Cr. The percentages of muscle, fat, bone, and skin from the right ham and the percentages of water, protein, lipid, and ash from the left carcass we re not significantly altered by Cr. The addition of 200 mu g/kg Cr fro m chromium picolinate increased(P < .07) the accretion rate of lipid i n the carcass. In Exp. 2, 42 individually penned pigs (three from each of 14 litters) were fed a fortified, corn-soybean meal basal diet (.9 5% lysine from 19 to 55 kg; .80% lysine from 55 to 109 kg) without or with 200 mu g/kg of Cr from chromium picolinate or 5,000 mu g/kg of Cr from CrCl3. Dietary Cr addition had no effect on the performance or b ackfat measurements of the pigs; however, both sources of Cr increased (P < .07) longissimus muscle area. The percentages and accretion rate s of muscle tissue were increased (P < .001) and the percentages of fa t tissue were decreased (P < .001) in pigs fed Cr, with chromium picol inate being more effective than CrCl3 (P < .05). The percentages (P < .01) and accretion rates (P < .07) of carcass protein were increased a nd the percentages and accretion rates of carcass lipid were decreased (P < .04) in pigs fed Cr. No changes in blood metabolites occurred as a result of supplemental Cr in either experiment. These results sugges t that chromium picolinate is more effective than CrCl3 and that Cr mu st be supplemented throughout the growing-finishing period to improve the carcass composition.