Effects of chromium propionate and metabolizable energy on growth, carcass traits, and pork quality of growing-finishing pigs

An experiment was conducted to evaluate the effects of Cr propionate (CrPr) and dietary metabolizable energy (ME) on growth, carcass traits, and pork quality of growing-finishing pigs. One-hundred forty-four Cambrough 22 barrows were allotted, to one of four dietary treatments in a randomized complete block design (six replicates of six pigs per replicate; average initial and final body weights were 27 and 113 kg, respectively). The dietary treatments were: 1) corn-soybean meal basal (13; LME), 2) B + 200 ppb Cr (as CrPr), 3) B + 200 kcal ME/kg (4.5% added fat; HME), 4) B + 200 kcal ME/kg + 200 ppb Cr. At trial termination, three pigs per replicate were killed to determine dietary effects on carcass traits and pork quality. Overall average daily gain, feed intake, and gain:feed were not affected (P > 0.10) by diet. During the early growing period, average daily gain was increased in pigs fed CrPr-LME diets, but decreased in pigs fed CrPr-HME diets (Cr x ME, P<0.04). Feed intake was increased in pigs fed the HME diets during the early growing period. No main effects of CrPr were observed (P > 0.10) for carcass and ham lean and fat measurements. Pigs fed the HME diets had increased (P < 0.07) backfat thickness and decreased (P < 0.05) percentage of muscling. Total ham fat (total body electrical conductivity) was increased in pigs fed CrPr-low ME diets, but not affected in pigs fed CrPr-high ME diets (P < 0.09). Subjective color and firmness-wetness scores, and 45 min and 24 h pH were not affected (P > 0.10) by diet. Minolta color (L*) was increased (P < 0.07) and shear force decreased (P < 0.06) in pigs fed HME diets. Subjective marbling was increased (P < 0.03) and longissimus dorsi percentage moisture and purge loss were decreased (P < 0.04) by CrPr. Chromium propionate, had no effect on growth and carcass traits in this experiment. However, CrPr did affect pork quality. The data indicate that CrPr may be a bioavailable source of Cr.