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Objective: Evaluating the differences in performance traits and carcass composition in Shal fattening lambs fed organic or inorganic chromium (Cr).
Design: Experimental study.
Animals: Seventy fat-tailed ram lambs of Shal breed with an average body weight (BW) of 37.0:t 2.8 kg, randomly partitioned in seven groups.
Procedure: Feeding a 60.5% barley-based diet (12.2% crude protein) supplemented with 0 (control), 200, 600, or 1000 19/kg dry matter of Cr from chromium nicotinate (CrNic) and 200, 600, or 1000 19/kg dry matter of Cr from chromium chloride (CrCI3) to individually penned lambs, measuring dry matter intake (DMI) and average daily gain (ADG) through wk 12, and slaughtering lambs and determining carcass characteristics at the end of wk 15 of the experiment.
Statistical analysis: Analysis of covariance for studying treatment differences and orthogonal coefficients for contrasting treatment groups.
Results: Addition of 600 or 1000 19/kg dietary dry matter of Cr from CrNic decreased ratio of DMI to % BW (P<0.04) but did not affect wk 6 and 12 body weights, ADG, daily DMI and ADG: DMI ratio. Backfat thickness increased by Cr (P<0.04). Addition of 1000 19/kg dry matter of Cr from CrNic increased loin-eye area (P<0.02) and muscle weight of right side carcass (P<0.04). Percentages of water, protein, lipid, or ash in carcass muscle were not affected by Cr supplements, whereas weights of protein and ash in carcass muscle increased by Cr with more positive effect of 1000 19/kg dry matter of Cr from CrNic (P<0.03).
Conclusion: The results of this study suggest that supplementation of chromium nicotinate may be beneficial for increasing lean tissue of Shal fattening lambs.
J.Fac. Vet.Med. Univ. Tehran. 59, 4:325-331,2004.