Individual Intake of Free-Choice Mineral Mix by Grazing Beef Cows May Be Less Than Typical Formulation Assumptions and Form of Selenium in Mineral Mix Affects Blood Se Concentrations of Cows and Their Suckling Calves

• Published in: Biological trace element research Vol. 155; no. 1; pp. 38 - 48
• Main Authors: Patterson, Jennifer D, Burris, Walter R, Boling, James A, Matthews, James C
• Format: Journal Article
• Language: English
• Published: Boston Springer-Verlag 01-10-2013; Springer US; Springer Nature B.V
• Subjects: Analysis of Variance; Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Animals, Suckling; Beef cattle; beef cows; Biochemistry; Biomedical and Life Sciences; Biotechnology; Blood; Body weight; Body Weight - drug effects; Body Weight - physiology; calves; Cattle; Dietary minerals; Dietary Supplements; Female; Festuca arundinacea; grazing; Life Sciences; Minerals - administration & dosage; Nutrition; Oncology; Organometallic Compounds - administration & dosage; Pasture; pastures; Random Allocation; Seasons; Selenium; Selenium - administration & dosage; Selenium - blood; sodium selenite; Sodium Selenite - administration & dosage; suckling; Time Factors; Trace elements; Weaning; Weight Gain - drug effects; Weight Gain - physiology; Selenium supplementation; Bovine; Ad libitum mineral intake; Blood
• ISSN: 0163-4984; 1559-0720
• DOI: 10.1007/s12011-013-9768-7

The objectives of this study were to determine (1) the individual ad libitum intake of mineral mix by beef cows managed under a year-long, fall-calving, forage-based production regimen and (2) if Se form in the mineral mix affected the blood Se concentrations of cows and suckling calves. Twenty-four late-gestation (6 to 8 months) Angus-cross cows (2.7 ± 0.8 years; body weight [BW] = 585 ± 58 kg) were blocked by BW and randomly assigned (n = 8) to a mineral supplement treatment (TRT) containing 35 ppm Se as either inorganic (ISe; sodium selenite), organic (OSe; Sel-Plex®), or a 1:1 combination of ISe/OSe (MIX). Cows commonly grazed a 10.1-ha predominately tall fescue pasture and had individual ad libitum access to TRT using in-pasture Calan gates. Cows calved from August to November and calves had common ad libitum access to creep feed and a mineral supplement that lacked Se. Cow jugular blood was taken at 28-day intervals (13 periods) and calf blood was taken with cows from birth through weaning. Individual cow mineral mix (mean = 54.0 ± 7.0 g/day, range = 97.3 to 27.9 ± 7.4 g/day) and Se (mean = 1.82 ± 0.25 mg/day, range = 3.31 to 0.95 ± 0.25 mg/day) intakes were affected by period (P < 0.0001), but not by cow Se TRT (P > 0.30). Cow blood Se (0.109 to 0.229 ± 0.01 μg/mL) was affected (P < 0.002) by period, Se form, and their interaction, with ISe < MIX for periods 8 and 11, ISe < OSe for all periods except period 1, and MIX < OSe for periods 2 to 4, 7, 8, 10, and 12. Calf blood Se (in micrograms Se per milliliter) was correlated with cow blood Se and affected (P < 0.0001) by cow Se TRT, with ISe (0.07 to 0.11) < MIX (0.10 to 0.15) = OSe (0.16 to 0.19). These data reveal that (1) mean supplemental ad libitum cow mineral intake was 36 % less than the typical formulation intake expectations (85 g/day) and, correspondingly, mean supplemental Se intake was 33 % less than that allowed by the FDA and (2) cow Se TRT differentially affected both cow and calf blood Se concentrations, resulting in adequate concentrations for all cows but inadequate concentrations for ISe calves.