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Animal Science Departmental Report 2004-2005 Return to Beef Cattle articles
Effects of Supplemental Chromium on Performance and Reproduction of
Beef Cattle H. S. Stahlhut, J. W. Spears, C. S. Whisnant, K. E. Lloyd, S. L. Hansen and L. R. Legleiter Introduction Chromium (Cr) is a trace mineral that functions by increasing the action of insulin in the body. Supplementing Cr has improved performance and enhanced immune response in stressed feeder calves. No research has been conducted to determine the effect of supplemental Cr on performance of beef cows and their calves. The objective of this study was to determine the effects of supplemental Cr, from Cr picolinate, on performance and reproduction of beef cows. Procedures One-hundred and fifty-two pregnant Angus and Simmental cows were blocked by breed and age and randomly assigned to one of two free choice mineral supplements. Supplements consisted of a control mineral or the control mineral supplemented with 40 ppm of Cr (as Cr picolinate). Cows were divided into three replicates per treatment, according to age with Angus and Simmental equally represented in each treatment. Replicate one contained cows 6 years of age or older. The second replicate contained cows 4 to 5 years of age. Replicate three was composed of 2 and 3 year old females. The study began approximately 75 days prior to calving. During the grazing season, cattle were rotated among tall fescue pastures at 14-day intervals to correct for any pasture differences. During the winter, cattle were fed grass hay free choice. In addition to hay, cows were fed 5.5 kg (dry matter) of corn silage and 0.9 kg corn gluten feed per head per day postpartum. Calves were born between day 43 (October 16) and 104 (December 15) of the study. Cows were synchronized using two doses of Lutalyse on days 141 and 152 and one dose of GnRH on day 145. Cows were observed for heat for 3 days and then time-bred on day 155. Beginning on day 159 (February 9), cows were exposed to Angus sires for 28 days. Rectal palpation was used to determine pregnancy. Animals were weighed at 28-day intervals throughout the 284-day study. Eighteen cows per treatment were bled via jugular venipuncture on days 28, 58, 97, 155, 210 and 279 for determination of plasma glucose and non-esterified fatty acid (NEFA) concentrations. Results and Discussion Based on mineral intake, Cr intake from the Cr picolinate treatment averaged 3.5 mg/cow/day. This approached our targeted supplemental Cr intake of 4.0 mg/cow/day. Plasma glucose concentrations were lower (P < 0.01) in Cr-supplemented cows. Chromium-supplemented cows had lower (P < 0.01) plasma NEFA concentrations shortly after calving (days 97 and 155). Young cows, (2 or 3 year-olds), not supplemented with Cr, lost more weight during the study than those receiving supplemental Cr (Table 1). The greater weight loss observed in control cows is consistent with the higher NEFA concentrations seen in control cows. Cows supplemented with Cr also tended to have higher pregnancy rates than control cows. The decreased weight loss, especially in the young cows, may explain the higher pregnancy rate in Cr-supplemented cows. Calf birth weights and weaning weights were not affected by Cr. Chromium supplementation tended to reduce the number of calves showing signs of morbidity during the study. However, mortality was similar across treatments. Summary Chromium is currently not approved for supplementation to beef cattle minerals. Results of the present study, indicates that Cr picolinate addition to a free choice mineral may improve reproductive performance and decrease weight loss following calving, especially in young cows.
Table 1. Effect of chromium supplementation on cow weight change and pregnancy rate
aTreatment x cow age interaction (P < 0.01). b,cMeans in a row with different superscripts differ (P < 0.01). d,eMeans in a row with different superscripts differ (P < 0.06).
Table 2. Effect of chromium supplementation on calf health and performance
aIncludes calves that were born dead. | |||||||||||||||||||||||||||||||||||||||