Methods of selenium supplementation to beef cows on blood, liver and milk selenium concentrations

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Methods of selenium supplementation to beef cows on blood, liver and milk selenium concentrations
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2009 Florida Beef Report
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Davis, Paul
McDowell, Lee
Buergelt, Claus
Wilkinson, Nancy
Van Alstyne, Rachel
Marshall, Tim
Weldon, Richard
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Institute of Food and Agricultural Sciences, University of Florida
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Gainesville, Fla.
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Methods of Selenium Supplementation to Beef Cows on Blood, Liver and
Milk Selenium Concentrations

Paul Davis1
Lee McDowell
Claus Buergelt
Nancy Wilkinson
Rachel Van Alstyne
Tim Marshall
Richard Weldon


Organic selenium was superior to other forms of supplementation in maintaining blood and milk
selenium adequate for nursing calves.


Summary
In a 365-d study, the effects ofform and method
of selenium (Se) supplementation on blood, milk,
and tissue Se in grazing beef cows were
evaluated. Forty-three Angus cows (115-130 d
gestation) were randomly assigned to 1 of 5
treatments and received either no Se
supplementation (control), one 9-mL barium
selenate injection at the initiation of the study,
one 5-mL sodium selenite injection + 68 IU
vitamin E at the initiation of the study and every
4 mo thereafter, or free-choice minerals
containing 26 iig kg Se as sodium selenite or Se
yeast (Sel-Plex). Cows receiving Se in free-
choice minerals were heavier and had a greater
increase (P < 0.05) in .h,,', i.,iht at d 365 than
cows receiving all other treatments. Liver Se at
d 365 was adequate ( 1,200 p. : k..- and greater
(P < 0.05) in Se yeast-treated cows than in all
other treatments. Cows receiving injectable
selenate also had adequate liver Se
concentrations that were greater (P < 0.05) than
the inadequate concentrations from control,
free-choice selenite or injectable selenite. At
205 d postpartum, cows receiving injectable
selenate and both free-choice treatments were
inadequate whole blood Se concentrations.
Cows receiving Se yeast produced colostrums


with greater (P < 0.05) Se concentration than
all others. At weaning (205 dpostpartum), cows
receiving Se yeast had at least 2-fold greater (P
< 0.05) milk Se than cows on other treatments.
Selenium supplementation with organic or
inorganic Se via free-choice minerals or
injectable selenate maintained adequate Se
concentrations in whole blood, plasma, and
liver. Inorganic Se was limited in its ability to
increase milk Se, whereas Se yeast increased
milk Se atparturition and at weaning.

Introduction
Many areas of the United States have soils that
are deficient in selenium (Se) (McDowell, 2003)
and may produce forages and grains that do not
provide adequate Se to livestock. Almost all
regions of Florida are severely deficient in Se
(McDowell and Arthington, 2003). Selenium
deficient brood cows may give birth to calves
which are stillborn, premature, weak, or afflicted
with nutritional muscular degeneration (Corah
and Ives, 1991). Likewise, even with adequate
blood Se at birth, calves suckling Se deficient
dams are susceptible to becoming Se deficient
(Pehrson et al., 1999; Gunter et al., 2003). The
objective of this experiment was to evaluate and


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compare effects of form and method of Se
supplementation on blood, liver, and milk Se
concentrations in beef cows.

Procedure
Animals were housed at the University of
Florida Boston Farm-Santa Fe Beef Unit located
in Northern Alachua County, Florida. On
August 6, 2002, 43 Angus cows, aged two to
three yr, (mean age = 2.67 yr) were palpated to
diagnose pregnancy and estimate days in
gestation. All cows were determined pregnant
and gestation estimates ranged from 115 to 130
d. Cows were weighed (average initial body
weitht (BW) = 919 101 lb), stratified by age
and assigned to one of five treatment groups for
a 365-d study. The 5 treatments were 1) no Se
supplementation (control), 2) one subcutaneous
injection of 9 mL (50 mg Se/mL) of barium
selenate (Deposel Multidose; Novartis New
Zealand, Ltd., Auckland, NZ) at the initiation of
the experiment, 3) three subcutaneous injections
of 5 mL (5 mg Se/mL) of sodium selenite with
68 IU vitamin E/mL as DL-alpha tocopheryl
acetate (Mu-Se; Schering-Plough Animal
Health, Union, NJ), one at the initiation of the
experiment and one every four mo thereafter, 4)
free-choice access to a mineral mixture
containing 26 mg/kg Se as sodium selenite
(Southeastern Minerals, Inc., Bainbridge, GA),
or 5) free-choice access to a mineral mixture
containing 26 mg/kg Se as Se yeast (Sel-Plex;
Alltech, Inc, Nicholasville, KY). All cows
grazed bahiagrass (Paspalum notatum) pastures
and were supplemented with bahiagrass hay, ad
libitum molasses-based liquid supplement, and
whole cottonseed and pelleted citrus pulp at
rates of 1.5 and 4.0 lb/d per cow, respectively,
from November 2002 through March 2003.
During the experiment pasture, blood, liver,
colostrum and later produced milk were
analyzed for Se by a fluorometric procedure.

Effects of treatment on change in BW were
analyzed using PROC MIXED in SAS (SAS for
Windows 8e; SAS Inst., Inc., Cary, NC) in a
completely randomized design with a diagonal
covariance structure. The PROC MIXED of
SAS was also used to analyze effects of
treatment, day, and the interaction of treatment x


day on BW, whole blood Se, milk Se, plasma
Se, and liver Se as repeated measures.

Results
Selenium concentration of pasture and hay for
all groups averaged 0.071 0.014 and 0.045
mg/kg (DM basis), respectively. Mineral
consumption, total amount of Se administered,
and total vitamin E supplemented are
summarized in Table 1. Both free-choice
treatment groups were similar and had a greater
increase in BW (P < 0.05) than did control and
the injectable Se treated groups.

Cow whole blood Se concentrations at intervals
postpartum are summarized in Table 2.
Significant effects of treatment (P < 0.001), day
(P < 0.001), and treatment x day (P = 0.013)
were observed. At parturition, whole blood Se
concentrations from cows receiving Deposel or
Sel-Plex were greater (P < 0.05) than whole
blood Se from controls and cows receiving Mu-
Se or free-choice selenite.

At calving, cows receiving Se via Deposel or
Sel-Plex had greater whole (P<0.05) blood Se
than did cows receiving no Se, Mu-Se, or
selenite in free-choice minerals. Whole blood
Se measured at 30 and 90 d postpartum followed
a similar pattern, with respect to treatment, to
whole blood Se at calving. Deposel and Sel-
Plex produced similar and consistently greater
whole blood Se than sodium selenite or no Se
supplementation. From d 90 to d 205
postpartum, whole blood Se decreased in
controls and cows receiving Mu-Se, and both
were below the adequate whole blood Se level
(> 100.ig/L). Cows receiving Se from Deposel
or either free-choice mineral mix maintained
blood Se above the adequate level from
parturition to 205 d postpartum. At d 205
postpartum, 100% of controls and 89% of cows
receiving Mu-Se had whole blood Se below the
adequate level.

Effects of treatment and d (P < 0.001) were
observed in Se concentration of milk collected at
the same postpartum intervals as whole blood
(Table 3). Cows receiving Sel-Plex had greater
(P < 0.05) Se concentrations in postsuckled


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colostrum than did cows receiving all other
treatments. Colostrum Se was similar (P > 0.54)
from control, Deposel, Mu-Se and free-choice
selenite treated cows. At 90 d postpartum, no
differences or tendencies were observed in milk
Se among treatment groups (P > 0.28).
Selenium in milk collected at 205 d postpartum,
was similar (P > 0.50) among control, Mu-Se,
Deposel, and free-choice selenite treatments.
Cows receiving Sel-Plex produced greater (P <
0.01) milk Se than cows receiving any other
form of Se supplementation. Milk Se from all
treatment groups decreased quadratically (P <
0.001) from parturition to 205 d postpartum.

Plasma Se concentrations were evaluated at d 0
and at d 365. Plasma Se concentrations in Sel-
Plex treated cows were greater (P < 0.005) than
from cows receiving any other treatment. After
1 yr, only cows receiving Sel-Plex had increased
(P < 0.001) plasma Se, data not shown.

Liver from biopsies at d 0 and d 365 was
evaluated for Se concentration (Table 4). Liver
Se (946 to 1136 .ig/kg) did not differ among
treatment groups at d 0 (P > 0.31). However, at
d 365, liver Se from Sel-Plex treated animals
was greater (P < 0.02) than from animals on all
other treatments. Liver Se concentrations from
cows receiving Se from Deposel or free-choice


selenite were similar, (P = 0.21) and both were
greater (P < 0.05) than those from controls and
cows receiving Mu-Se. At the end of this study,
liver Se had increased (P < 0.001) in cows
receiving Sel-Plex. Cows receiving Mu-Se had
decreased (P <0.01) liver Se, which tended to
decrease (P = 0.07) in controls. Liver Se
remained unchanged (P = 0.48; 0.73) in cows
receiving Deposel and free-choice mineral with
sodium selenite, respectively. Liver and plasma
Se concentrations were highly correlated (P <
0.001; r = 0.71). In spite of the high degree of
correlation, the authors suggest that liver Se
continue to be used where possible to help
validate plasma, whole blood Se concentrations,
or both.

Sel-Plex supplemented cows had greater Se
concentration in liver at the end of our study
than did cows receiving any other treatment.
Sel-Plex produced liver Se concentrations up to
3-fold greater than Mu-Se. At the termination of
the experiment, 100% of cows supplemented
with selenite, free-choice or injectable, and cows
receiving no supplemental Se had plasma Se
concentrations below the critical level of > 70
ig/L.


Literature Cited
Corah and Ives. 1991. Vet Clin. North Am. Food Anim. Pract. 7:41.
Gunter et al. 2003. J. Anim. Sci. 81:856.
McDowell. 2003. Minerals in Animal and Human Nutrition, Elsevier Science, Amsterdam.
McDowell and Arthington. 2005. Minerals for Grazing Ruminants in Tropical Regions, Dept. Animal
Sci., Gainesville.
Pehrson et al. 1999. J. Anim. Sci. 77:3371.

Acknowledgments
Special thanks go to Southeastern Minerals Inc., Flint River Mills, U.S. Sugar Corp., and Alltech Inc. for
donation of products or services to aid in this research, to E.Y. Matsuda-Fugisaki for assistance in
analyses of blood and tissues, and to Steve Chandler and Bert Faircloth for animal care and feeding.

'Paul Davis, Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist; Tim
Marshall, Professor; Rachel Van Alstyne, Former Graduate Student; UF/IFAS, Department of Animal
Sciences, Gainesville, FL; Claus Buergelt, Professor, College of Veterinary Medicine, Gainesville, FL;
Richard Weldon, Professor, Food and Resource Economics, Gainesville, FL.


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Table 1. Frequency, daily amount, and total of amount of supplemental Se administered to cows

Selenium Avg Se Total Se Total Vitamin E
supplementation supplementation, supplementation, supplementation,
Source of supplemental Se interval, d mg Se/cow per d mg IU
No Se supplementation -1 235
Barium selenate2 (Deposel) 365 1.23 450 235
Sodium selenite3 (Mu-Se) 125 0.21 75 1255
Free-choice mineral mix4 (sodium 16 1.08 393 158
1 1.08 393 158
selenite)
Free-choice mineral mix5 (Sel-Plex) 16 2.22 811 326
1Cows received no Se supplementation or injectable Se had free-choice access to and consumed the basal free-choice mineral
mix (no Se) at an average of 62.2 g/d per cow.
2Cows received a s.c injection of 9 mL Deposel at d 0.
3Cows received a s.c. injection of 5 mL Mu-Se every four mo beginning at d 0.
4Cows had continuous access to free-choice mineral mix containing 26 mg Se/kg as sodium selenite and consumed mineral
mix at an average of 41.5 g/d per cow.
5Cows had continuous access to free-choice mineral mix containing 26 mg Se/kg as Se yeast and consumed mineral mix at an
average of 85.5 g/d/ per cow.
6 Access to free-choice minerals containing Se was continuous throughout the study.


Table 2. Whole blood Se concentrations of cows receiving different sources and forms of Se supplementation at
various days postpartum1
Days postpartum
0 30 90 205
Source of Se supplementation Whole blood Se, [tg/L
Control (No Se) 143a+ 15 162a+ 15 121a+ 15 74 a 15
Barium Selenate2 (Deposel) 235b 12 207bc + 12 166bc 12 156b + 12
Sodium Selenite3 (Mu-Se) 173a + 13 178ac + 12 127ad + 12 89a + 12
Free Choice Mineral Mix4 ( Sodium selenite) 159a + 12 184ac + 13 140cd 13 155b + 13
Free Choice Mineral Mix5 (Sel-Plex) 216b 12 241b + 12 185b + 12 198 + 12
a-dMeans within columns lacking a common superscript differ (P < 0.05).
'Data represent least squares means SE; n = 41/d; adequate Se level in whole blood is > 100 pg/L.
2Cows received a s.c. injection of 9 mL Deposel at d 0.
3Cows received a s.c. injection of 5 mL Mu-Se every four mo beginning at d 0.
4Cows consumed free-choice mineral mix containing 26 mg/kg Se as sodium selenite at an average of 41.5 g/d per cow
beginning at d 0.
5Cows consumed free-choice mineral mix containing 26 mg/kg Se as Se yeast at an average of 85.5 g/d per cow
beginning at d 0.


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Table 3. Milk Se concentrations of cows receiving different sources and forms of Se supplementation at various days
postpartum1
Days postpartum
0 30 90 205
Source of Se supplementation Milk Se, [g/L
Control (No Se) 39a 7 14 7 6 7 15a 7
Barium Selenate2 (Deposel) 34a 6 15 6 15 6 21a + 6
Sodium Selenite3 (Mu-Se) 35a + 6 13 + 6 6 6 16a + 6
Free Choice Mineral Mix4 ( Sodium selenite) 39a + 7 26 + 6 16 + 6 15a + 7
Free Choice Mineral Mix5 (Sel-Plex) 71b + 6 27 6 15 + 6 42b + 6
a bMeans within columns with different superscripts differ (P < 0.05).
'Data represent least squares means SE; n = 41 for each sample day.
2Cows received a s.c. injection of 9 mL Deposel at d 0.
3Cows received a s.c. injection of 5 mL Mu-Se every four mo beginning at d 0.
4Cows consumed free-choice mineral mix containing 26 mg/kg Se as sodium selenite at an average of 41.5 g/d per cow
beginning at d 0.
5Cows consumed free-choice mineral mix containing 26 mg/kg Se as Se yeast at an average of 85.5 g/d per cow
beginning at d 0.













Table 4. Liver Se concentration (DM basis) at d 0 and d 365 of beef cows that received different sources and forms of
Se supplementation'
dO d365
Source of Se Supplementation Liver Se, [g/kg Liver Se, [g/kg
Control (No Se) 973 + 129 642 129a
Barium Selenate2 (Deposel) 1136 + 105 1240 105b
Sodium Selenite3 (Mu-Se) 946 + 105 537 + 105a
Free Choice Mineral Mix4 (Sodium selenite) 1089 + 105 1046 + 105b
Free Choice Mineral Mix5 (Sel-Plex) 1011+ 105 1604 + 105c
a-cMeans within columns lacking a common superscript differ (P < 0.05).
'Data represent least squares means SE; n = 42 and 41 for d 0 and d 365, respectively; adequate Se concentration in
liver is > 1,200 gg/kg.
2Cows received a s.c. injection of 9 mL Deposel at d 0.
3Cows received a s.c. injection of 5 mL Mu-Se every four mo beginning at d 0.
4Cows consumed free-choice mineral mix containing 26 mg Se/kg as sodium selenite at an average of 41.5 g/d per
cow beginning at d 0.
5Cows consumed free-choice mineral mix containing 26 mg Se/kg as Se yeast at an average of 85.5 g/d per cow
beginning at d 0.


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Full Text

PAGE 1

Methods of Selenium Supplementation to Beef Cows on Blood, Liver and Milk Selenium Concentrations Paul Davis 1 Lee McDowell Claus Buergelt Nancy Wilkinson Rachel Van Alstyne Tim Marshall Richard Weldon Summary In a 365-d study, the effects of form and method of selenium (Se) supplementation on blood, milk, and tissue Se in grazing beef cows were evaluated. Forty-three Angus cows (115-130 d gestation) were randomly assigned to 1 of 5 treatments and received either no Se supplementation (control), one 9-mL barium selenate injection at the initiation of the study, one 5-mL sodium selenite injection + 68 IU vitamin E at the initiation of the study and every 4 mo thereafter, or free-choice minerals containing 26 mg/kg Se as sodium selenite or Se yeast (Sel-Plex). Cows receiving Se in freechoice minerals were heavier and had a greater increase (P < 0.05) in bodyweight at d 365 than cows receiving all other treatments. Liver Se at d 365 was adequate (> 1,200 g/kg) and greater (P < 0.05) in Se yeast-treated cows than in all other treatments. Cows receiving injectable selenate also had adequate liver Se concentrations that were greater (P < 0.05) than the inadequate concentrations from control, free-choice selenite or injectable selenite. At 205 d postpartum, cows receiving injectable selenate and both free-choice treatments were inadequate whole blood Se concentrations. Cows receiving Se yeast produced colostrums with greater (P < 0.05) Se concentration than all others. At weaning (205 d postpartum), cows receiving Se yeast had at least 2-fold greater (P < 0.05) milk Se than cows on other treatments. Selenium supplementation with organic or inorganic Se via free-choice minerals or injectable selenate maintained adequate Se concentrations in whole blood, plasma, and liver. Inorganic Se was limited in its ability to increase milk Se, whereas Se yeast increased milk Se at parturition and at weaning. Introduction Many areas of the United States have soils that are deficient in selenium (Se) (McDowell, 2003) and may produce forages and grains that do not provide adequate Se to livestock. Almost all regions of Florida are severely deficient in Se (McDowell and Arthington, 2003). Selenium deficient brood cows may give birth to calves which are stillborn, premature, weak, or afflicted with nutritional muscular degeneration (Corah and Ives, 1991). Likewise, even with adequate blood Se at birth, calves suckling Se deficient dams are susceptible to becoming Se deficient (Pehrson et al., 1999; Gunter et al., 2003). The objective of this experiment was to evaluate and Organic selenium was superior to other forms of supplementation in maintaining blood and milk selenium adequate for nursing calves.

PAGE 2

compare effects of form and method of Se supplementation on blood, liver, and milk Se concentrations in beef cows. Procedure Animals were housed at the University of Florida Boston Farm-Santa Fe Beef Unit located in Northern Alachua County, Florida. On August 6, 2002, 43 Angus cows, aged two to three yr, (mean age = 2.67 yr) were palpated to diagnose pregnancy and estimate days in gestation. All cows were determined pregnant and gestation estimates ranged from 115 to 130 d. Cows were weighed (average initial body weitht (BW) = 919 101 lb), stratified by age and assigned to one of five treatment groups for a 365-d study. The 5 treatments were 1) no Se supplementation (control), 2) one subcutaneous injection of 9 mL (50 mg Se/mL) of barium selenate (Deposel Multidose ; Novartis New Zealand, Ltd., Auckland, NZ) at the initiation of the experiment, 3) three subcutaneous injections of 5 mL (5 mg Se/mL) of sodium selenite with 68 IU vitamin E/mL as DL-alpha tocopheryl acetate (MuSe ; Schering-Plough Animal Health, Union, NJ), one at the initiation of the experiment and one every four mo thereafter, 4) free-choice access to a mineral mixture containing 26 mg/kg Se as sodium selenite (Southeastern Minerals, Inc., Bainbridge, GA), or 5) free-choice access to a mineral mixture containing 26 mg/kg Se as Se yeast (Sel-Plex ; Alltech, Inc, Nicholasville, KY). All cows grazed bahiagrass ( Paspalum notatum) pastures and were supplemented with bahiagrass hay, ad libitum molasses-based liquid supplement, and whole cottonseed and pelleted citrus pulp at rates of 1.5 and 4.0 lb/d per cow, respectively, from November 2002 through March 2003. During the experiment pasture, blood, liver, colostrum and later produced milk were analyzed for Se by a fluorometric procedure. Effects of treatment on change in BW were analyzed using PROC MIXED in SAS (SAS for Windows 8e; SAS Inst., Inc., Cary, NC) in a completely randomized design with a diagonal covariance structure. The PROC MIXED of SAS was also used to analyze effects of treatment, day, and the interaction of treatment day on BW, whole blood Se, milk Se, plasma Se, and liver Se as repeated measures. Results Selenium concentration of pasture and hay for all groups averaged 0.071 0.014 and 0.045 mg/kg (DM basis), respectively. Mineral consumptions, total amount of Se administered, and total vitamin E supplemented are summarized in Table 1. Both free-choice treatment groups were similar and had a greater increase in BW ( P < 0.05) than did control and the injectable Se treated groups. Cow whole blood Se concentrations at intervals postpartum are summarized in Table 2. Significant effects of treatment ( P < 0.001), day ( P < 0.001), and treatment day ( P = 0.013) were observed. At parturition, whole blood Se concentrations from cows receiving Deposel or Sel-Plex were greater ( P < 0.05) than whole blood Se from controls and cows receiving MuSe or free-choice selenite. At calving, cows receiving Se via Deposel or Sel-Plex had greater whole (P<0.05) blood Se than did cows receiving no Se, Mu-Se, or selenite in free-choice minerals. Whole blood Se measured at 30 and 90 d postpartum followed a similar pattern, with respect to treatment, to whole blood Se at calving. Deposel and SelPlex produced similar and consistently greater whole blood Se than sodium selenite or no Se supplementation. From d 90 to d 205 postpartum, whole blood Se decreased in controls and cows receiving Mu-Se, and both were below the adequate whole blood Se level (> 100g/L). Cows receiving Se from Deposel or either free-choice mineral mix maintained blood Se above the adequate level from parturition to 205 d postpartum. At d 205 postpartum, 100% of controls and 89% of cows receiving Mu-Se had whole blood Se below the adequate level. Effects of treatment and d ( P < 0.001) were observed in Se concentration of milk collected at the same postpartum intervals as whole blood (Table 3). Cows receiving Sel-Plex had greater ( P < 0.05) Se concentrations in postsuckled

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colostrum than did cows receiving all other treatments. Colostrum Se was similar ( P > 0.54) from control, Deposel, Mu-Se and free-choice selenite treated cows. At 90 d postpartum, no differences or tendencies were observed in milk Se among treatment groups ( P > 0.28). Selenium in milk collected at 205 d postpartum, was similar ( P > 0.50) among control, Mu-Se, Deposel, and free-choice selenite treatments. Cows receiving Sel-Plex produced greater ( P < 0.01) milk Se than cows receiving any other form of Se supplementation. Milk Se from all treatment groups decreased quadratically ( P < 0.001) from parturition to 205 d postpartum. Plasma Se concentrations were evaluated at d 0 and at d 365. Plasma Se concentrations in SelPlex treated cows were greater ( P < 0.005) than from cows receiving any other treatment. After 1 yr, only cows receiving Sel-Plex had increased ( P < 0.001) plasma Se, data not shown. Liver from biopsies at d 0 and d 365 was evaluated for Se concentration (Table 4). Liver Se (946 to 1136 g/kg) did not differ among treatment groups at d 0 ( P > 0.31). However, at d 365, liver Se from Sel-Plex treated animals was greater ( P < 0.02) than from animals on all other treatments. Liver Se concentrations from cows receiving Se from Deposel or free-choice selenite were similar, ( P = 0.21) and both were greater ( P < 0.05) than those from controls and cows receiving Mu-Se. At the end of this study, liver Se had increased ( P < 0.001) in cows receiving Sel-Plex. Cows receiving Mu-Se had decreased ( P <0.01) liver Se, which tended to decrease ( P = 0.07) in controls. Liver Se remained unchanged ( P = 0.48; 0.73) in cows receiving Deposel and free-choice mineral with sodium selenite, respectively. Liver and plasma Se concentrations were highly correlated ( P < 0.001; r = 0.71). In spite of the high degree of correlation, the authors suggest that liver Se continue to be used where possible to help validate plasma, whole blood Se concentrations, or both. Sel-Plex supplemented cows had greater Se concentration in liver at the end of our study than did cows receiving any other treatment. Sel-Plex produced liver Se concentrations up to 3-fold greater than Mu-Se. At the termination of the experiment, 100% of cows supplemented with selenite, free-choice or injectable, and cows receiving no supplemental Se had plasma Se concentrations below the critical level of > 70 g/L. Literature Cited Corah and Ives. 1991. Vet Clin. North Am. Food Anim. Pract. 7:41. Gunter et al. 2003. J. Anim. Sci. 81:856. McDowell. 2003. Minerals in Animal and Human Nutrition, Elsevier Science, Amsterdam. McDowell and Arthington. 2005. Minerals for Grazing Ruminants in Tropical Regions, Dept. Animal Sci., Gainesville. Pehrson et al. 1999. J. Anim. Sci. 77:3371. Acknowledgments Special thanks go to Southeastern Minerals Inc., Flint River Mills, U.S. Sugar Corp., and Alltech Inc. for donation of products or services to aid in this research, to E.Y. Matsuda Fugisaki for assistance in analyses of blood and tissues, and to Steve Chandler and Bert Faircloth for animal care and feeding. 1 Paul Davis, Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist; Tim Marshall, Professor; Rachel Van Alstyn e, Former Graduate Student; UF/IFAS, Department of Animal Sciences, Gainesville, FL; Claus Buergelt, Professor, College of Veterinary Medicine, Gainesville, FL; Richard Weldon, Professor, Food and Resource Economics, Gainesville, FL.

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Table 1. Frequen cy, daily amount, and total of amount of supplemental Se administered to cows Source of supplemental Se Selenium supplementation interval, d Avg Se supplementation, mg Se/cow per d Total Se supplementation, mg Total Vitamin E supplementation, IU No Se supplementation 1 1 1 235 Barium selenate 2 (Deposel) 365 1.23 450 235 Sodium selenite 3 (Mu Se) 125 0.21 75 1255 Free choice mineral mix 4 (sodium selenite) 1 6 1.08 393 158 Free choice mineral mix 5 (Sel Plex) 1 6 2.22 811 326 1 Cows received no Se supplementation or injectable Se had free choice access to and consumed the basal free choice mineral mix (no Se) at an average of 62.2 g/d per cow. 2 Cows received a s.c injection of 9 mL Deposel at d 0. 3 Cows received a s.c injection of 5 mL Mu Se every four mo beginning at d 0. 4 Cows had continuous access to free choice mineral mix containing 26 mg Se/kg as sodium selenite and consumed mineral mix at an average of 41.5 g/d per cow. 5 Cows had continuous access to free cho ice mineral mix containing 26 mg Se/kg as Se yeast and consumed mineral mix at an average of 85.5 g/d/ per cow. 6 Access to free choice minerals containing Se was continuous throughout the study. Table 2. Whole blood Se concentrations of cows receiv ing different sources and forms of Se supplementation at various days postpartum 1 Days postpartum 0 30 90 205 Source of Se supplementation Whole blood Se, g/L Control (No Se) 143 a 15 162 a 15 121 a 15 74 a 15 Barium Selenate 2 (Deposel) 235 b 12 207 bc 12 166 bc 12 156 b 12 Sodium Selenite 3 (Mu Se) 173 a 13 178 ac 12 127 ad 12 89 a 12 Free Choice Mineral Mix 4 ( Sodium selenite) 159 a 12 184 ac 13 140 cd 13 155 b 13 Free Choice Mineral Mix 5 (Sel Plex) 216 b 12 241 b 12 185 b 12 198 c 12 a d Means within columns lacking a common superscript differ (P < 0.05). 1 2 Cows received a s.c. injection of 9 mL Deposel at d 0. 3 Cows received a s.c. injection of 5 mL Mu Se every four mo beginning at d 0. 4 Cows consumed free choice mineral mix containing 26 mg/kg Se as sodium selenite at an average of 41.5 g/d per cow beginning at d 0. 5 Cows consumed free choice mineral mix containing 26 mg/kg Se as Se yeast at an average of 85.5 g/d per cow beginning at d 0.

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Table 3. Milk Se concentrations of cows receiving different sources and forms of Se supplementation at various days post partum 1 Days postpartum 0 30 90 205 Source of Se supplementation Milk Se, g/L Control (No Se) 39 a 7 14 7 6 7 15 a 7 Barium Selenate 2 (Deposel) 34 a 6 15 6 15 6 21 a 6 Sodium Selenite 3 (Mu Se) 35 a 6 13 6 6 6 16 a 6 Free Choice Mineral Mix 4 ( Sodium selenite) 39 a 7 26 6 16 6 15 a 7 Free Choice Mineral Mix 5 (Sel Plex) 71 b 6 27 6 15 6 42 b 6 a.b Means within columns with different superscripts differ (P < 0.05). 1 Data represent least squares means SE; n = 41 for each sample day. 2 Cows received a s.c. injection of 9 mL Deposel at d 0. 3 Cows received a s.c. injection of 5 mL Mu Se every four mo beginning at d 0. 4 Cows consumed free choice mineral mix containing 26 mg/kg Se as sodium selenite at an average of 41.5 g/d per cow beginning at d 0. 5 Cows consumed free choice mineral mix containing 26 mg/kg Se as Se yeast at an average of 85.5 g/d per cow beginning at d 0. Table 4. Liver Se concentration (DM basis) at d 0 and d 365 of beef cows that received different sources and forms of Se supplementation 1 d 0 d 365 Source of Se Supplementation Liver Se, g/kg Liver Se, g/kg Control (No Se) 973 129 642 129 a Barium Selenate 2 (Deposel) 1136 105 1240 105 b Sodium Selenite 3 (Mu Se) 946 105 537 105 a Free Choice Mineral Mix 4 (Sodium selenite) 1089 105 1046 105 b Free Choice Mineral Mix 5 (Sel Plex) 1011 105 1604 105 c a c Means within columns lacking a common superscript differ (P < 0.05). 1 Data represent least squares means SE; n = 42 and 41 for d 0 and d 365, respectively; adequate Se concentration in 2 Cows received a s.c. injection of 9 mL Deposel at d 0. 3 Cows received a s.c. injection of 5 mL Mu Se every four mo beginning at d 0. 4 Cows consumed free choice mineral mix containing 26 mg Se/kg as sodium selenite at an average of 41.5 g/d per cow beginning at d 0. 5 Cows consumed free choice mineral mix containing 26 mg Se/kg as Se yeast at an average of 85.5 g/d per cow beginning at d 0.