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Effects of Cr Supplementation during Gestation on Beef Cow Performance and the Interaction with Cr during Finishing on Progeny Growth Performance and Carcass Characteristics
Objectives were to determine effects of supplemental Cr-propionate (Cr) during cow gestation on cow milk production and performance, and the interaction of supplemental Cr during cow gestation and feedlot finishing on progeny growth performance, intramuscular fat, and other carcass characteristics. Spring-calving, mature cows (n = 66; initial BW = 508 ± 100 kg) were fed 1 of 2 supplements from mid- through late gestation (128 d): 1) 1.81 kg pelleted corn fortified with 3 mg Cr∙d-1, or 2) 1.81 kg pelleted corn with no supplemental Cr. There was no effect (P ≥ 0.10) of treatment on cow BW and BCS change. Supplementation with Cr did not affect milk production at 90 d (P = 0.20) or 180 d (P = 0.89). There was no effect of treatment on calf birth BW (P = 0.40) or weaning BW (P = 0.56). Steer progeny (n = 34) were used in a 2×2 factorial arrangement of treatments: with the first factor being gestational Cr and the second factor being 0 or 3 mg Cr∙d-1 supplementation during the finishing phase. Steers were slaughtered at a targeted 1.27 cm backfat. There was an interaction (P < 0.01) of dam and feedlot treatment on days on feed (DOF). Steers from dams fed Cr that also were fed Cr in the feedlot were fed the longest, while steers from dams fed Cr that were not fed Cr in the feedlot had the fewest DOF; steers from dams not fed Cr were intermediate and different from both. Steers from dams fed Cr gained 0.12 kg∙d-1 less (trend; P = 0.09) than steers from dams not fed Cr during gestation, regardless of feedlot treatment. Proportion of carcasses grading Low Choice and above was fewest (trend; P = 0.10) for steers receiving Cr during fetal development and finishing, but greatest for steers receiving Cr only once; steers never receiving Cr were intermediate and different from both. Steers fed Cr during finishing had the greatest (P = 0.01) dressing percentage, regardless of gestational supplementation. Supplementation with Cr during gestation did not alter cow milk production or BW and BCS. Supplementation of Cr during both fetal development and finishing increased DOF and tended to decrease proportion of Low Choice and above carcasses, when compared to other treatments. Steers from dams fed Cr tended to gain less in the feedlot, while steers fed Cr only in the feedlot had the greatest dressing percentage.
Keywords:
beef, chromium, fetal programming