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United States Department of Agriculture

Agricultural Research Service

Title: Mineral Concentrations and Availability of Forages for Grazing Livestock in the Northern Great Plains

Authors
item Poland, W - NORTH DAKOTA STATE UNIV
item Grings, Elaine
item Karn, James
item Manske, L - NORTH DAKOTA STATE UNIV

Submitted to: DREC Livestock Research Roundup
Publication Type: Proceedings
Publication Acceptance Date: October 1, 1999
Publication Date: October 1, 1999
Citation: POLAND, W.W., GRINGS, E.E., KARN, J.F., MANSKE, L. MINERAL CONCENTRATIONS AND AVAILABILITY OF FORAGES FOR GRAZING LIVESTOCK IN THE NORTHERN GREAT PLAINS. DREC LIVESTOCK RESEARCH ROUNDUP. 1999. p. 37.

Interpretive Summary: Twenty-four steers (avg 410 kg) were fed alfalfa or western wheatgrass hay at either 1.90 or 2.35% of BW for 91 d to evaluate the effects of hay type and feeding level on tissue trace mineral concentrations. At the end of the feeding period, steers were slaughtered at a commercial abattoir. Tissue weights and samples were collected; samples were oven dried and analyzed for Cu, Zn, Mn, and Fe by atomic absorption spectrophotometry. Data were analyzed with a model including hay source and intake level, their interactions, and BW as a covariate. Alfalfa hay contained 7 ppm Cu, 17 ppm Zn, 30 ppm Mn, 426 ppm Fe, and 3.6 ppm Mo. Grass hay contained 2 ppm Cu, 20 ppm Zn, 29 ppm Mn, 143 ppm Fe, and 1.3 ppm Mo. Increasing hay intake by 124% increased intake of minerals but had little effect on tissue mineral concentrations. Heart Cu concentrations were greater in steers on the high than low intake level. Kidney Zn concentrations were affected by the hay source by level interaction. Liver weights averaged 1,466 g DM for alfalfa-fed and 1,276 g DM for grass-fed steers. On a dry tissue basis, total liver Cu, Zn, and Mn were affected by hay source, being greater in alfalfa-fed than grass-fed steers. For Zn and Mn this was due to increased liver weight but for Cu it was related to both increased concentration and liver weight in alfalfa-fed steers. Heart Zn concentrations and total heart Zn were greater for grass-fed (80.3 ppm and 25.7 mg) than alfalfa-fed steers. Kidney, heart, and muscle Mn concentrations were greater for alfalfa-fed than grass-fed steers even though Mn intake were similar. Differences in tissue mineral concentrations among steers fed different hays are related to more than mineral intake.

Technical Abstract: Twenty-four steers (avg 410 kg) were fed alfalfa or western wheatgrass hay at either 1.90 or 2.35% of BW for 91 d to evaluate the effects of hay type and feeding level on tissue trace mineral concentrations. At the end of the feeding period, steers were slaughtered at a commercial abattoir. Tissue weights and samples were collected; samples were oven dried and analyzed for Cu, Zn, Mn, and Fe by atomic absorption spectrophotometry. Data were analyzed with a model including hay source and intake level, their interactions, and BW as a covariate. Alfalfa hay contained 7 ppm Cu, 17 ppm Zn, 30 ppm Mn, 426 ppm Fe, and 3.6 ppm Mo. Grass hay contained 2 ppm Cu, 20 ppm Zn, 29 ppm Mn, 143 ppm Fe, and 1.3 ppm Mo. Increasing hay intake by 124% increased intake of minerals but had little effect on tissue mineral concentrations. Heart Cu concentrations were greater in steers on the high than low intake level. Kidney Zn concentrations were affected by the hay source by level interaction. Liver weights averaged 1,466 g DM for alfalfa-fed and 1,276 g DM for grass-fed steers. On a dry tissue basis, total liver Cu, Zn, and Mn were affected by hay source, being greater in alfalfa-fed than grass-fed steers. For Zn and Mn this was due to increased liver weight but for Cu it was related to both increased concentration and liver weight in alfalfa-fed steers. Heart Zn concentrations and total heart Zn were greater for grass-fed (80.3 ppm and 25.7 mg) than alfalfa-fed steers. Kidney, heart, and muscle Mn concentrations were greater for alfalfa-fed than grass-fed steers even though Mn intake were similar. Differences in tissue mineral concentrations among steers fed different hays are related to more than mineral intake.

Last Modified: 12/18/2014
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