Bioavailability of vitamin A (retinol) sources for cattle

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Bioavailability of vitamin A (retinol) sources for cattle
Series Title:
2009 Florida Beef Report
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Book
Creator:
Alosilla, Carlos Jr.
McDowell, Lee
Wilkinson, Nancy
Staples, Charles
Thatcher, William
Blair, Michael
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Institute of Food and Agricultural Sciences, University of Florida
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Gainesville, Fla.
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University of Florida
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Bioavailability of Vitamin A (Retinol) Sources for Cattle


Carlos Alosilla, Jr.1
Lee McDowell
Nancy Wilkinson
Charles Staples
William Thatcher
Michael Blair


Vitamin A destruction occurs in the rumen with retinol losses up to 80%. For the sources of vitamin A
studied Microvit A and Rovamix A appear to be more available to cattle.


Summary
An experiment was conducted to evaluate
bioavailability of five sources of vitamin A
(retinol). Fifty-three yearling Angus x Brahman
cattle, consisting of 39 steers and 14 heifers,
were stratified by BWand gender and randomly
assigned to six high concentrate diet groups
receiving either no vitamin A supplementation
(control), or vitamin A supplemented from the
following sources: Microvit A (ADISSEO,
Acworth, GA), Rovamix A (DSM, Parsippany,
NJ), Sunvit A, Lutavit A, and Microvit A DLC
(ADISSEO). Vitamin A treatment groups were
fed daily 80,000 IU retinol/animal in a low
retinol concentrate diet (78.5% oats, 10%
cottonseed hulls, 8% molasses, and 2%
cottonseed meal) for 84 d. Every 28 d body
weight was determined and liver biopsies and
plasma were collected and analyzed for retinol
concentrations. All retinol treatments showed
significant increases in liver retinol
concentrations compared to control animals (P
< 0.0001), which steadily decreased over time.
At all collection times, Microvit A led to
numerically greater concentrations of retinol in
liver than did all other treatments. However, at
experiment termination, there was no i,i ..inft
difference in liver retinol concentration among
Microvit A, Rovamix A, Lutavit A, and Microvit
A DLC diets. When liver retinol concentrations


at all collection times were considered, Microvit
A and Rovamix A appeared to provide the most
bioavailable vitamin A.

Introduction
Vitamin A generally is supplemented to
ruminant diets to insure maximum health and
productivity. Unfortunately, considerable
supplemental retinol is destroyed by ruminal
microbes. The amount of concentrate in a diet is
one factor associated with ruminal destruction.
Rode et al. (1990) reported an 80% loss of
vitamin A when cattle were fed 70% concentrate
diets, but, when fed high-forage diets, losses
were only 20%. There is a need for minimizing
ruminal destruction to increase the amount of
vitamin A that reaches the duodenum. In order
to protect vitamin A from pre-intestinal
destruction, gelatin beadlets have been
developed commercially that contain not only
vitamin A but also carbohydrates and
antioxidants to stabilize the vitamin A. The
objective of this study was to compare the
bioavailability of five different forms of
supplemental vitamin A fed to beef cattle.

Procedure
Fifty-three yearling Angus x Brahman cattle,
consisting of 39 steers and 14 heifers, that


2009 Florida BeefReport










weighed 750.2 + 44 lbs, were stratified by
gender and BW and assigned randomly to one of
seven pens and one of eight Calan gates
(American Calan, Northwood, NH) within pens
at the University of Florida Beef Research Unit
in August of 2002. High concentrate dietary
treatments included 78.5% oats, 10% cottonseed
hulls, 8% molasses, and 2% cottonseed meal.
Experimental treatments were control (no
supplemental vitamin A), Microvit A
(ADISSEO, Acworth, GA), Rovamix A (DSM,
Parsippany, NJ), Sunvit A, Lutavit A, and
Microvit A DLC (ADISSEO) fed daily at 80,000
IU/animal. Vitamin A pre-mixes were
formulated and mixed every two wk. Feed
intake gradually increased, therefore vitamin A
additions changed so that cattle always received
80,000 IU/d. A total of nine cattle were used per
treatment except for eight in the control group.
In each pen, poor quality Bermuda grass hay
(low vitamin A content, 0.71 ig of P-carotene/g)
and water were supplied for ad libitum
consumption.

On d 0, 28, 56, and 84, all animals were
restrained and weighed, and liver biopsy and
blood samples were collected. Vitamin A was
analyzed by a standardized HPLC system. The
experiment was a completely random design. All
data were analyzed using the Mixed Procedure
of SAS (SAS for Windows 8e; SAS Institute,
Inc., Cary, NC) for repeated measures. The
model included terms for a covariate (value from
d 0), treatment, time, and treatment x time.

Results
Body weights increased with time (P < 0.0001),
but there were no effects of treatment (P = 0.86)
or of treatment x time (P = 0.31) detected. As
there were no differences among treatments,
control cattle with minimal dietary vitamin A
were able to rely on storage reserves of retinol
for body growth.

Retinol concentrations in plasma (Table 1) were
affected by treatment (P = 0.01) and time (P =
0.04). There were no interactions between
treatment and time (P = 0.96). Using d 0 values
as the covariate, both Microvit A and Rovamix
A increased (P < 0.05) plasma retinol (d 84 and


overall) compared to control and also compared
to the Sunvit A treatment groups (P < 0.05). On
d 84, both Lutavit A and Microvit A DLC were
intermediate and did not differ from control;
Lutavit A also did not differ from Microvit A or
Rovamix A, and Microvit A DLC did not differ
from Microvit A. Similar trends at d 28 and d
56 were evident.

Retinol concentrations in liver (Table 2) were
affected by treatment (P < 0.01) and a treatment
x time interaction was detected (P < 0.0001);
retinol-supplemented cattle had greater (P <
0.05) and more sustained concentrations of liver
retinol compared to a steady decline for the
control group through d 84 (Table 2). Overall
Microvit A had the numerically highest
concentration of liver retinol, but it did not differ
statistically from Rovamix A and Lutavit A.
However, averaged over all sampling times,
Microvit A led to greater liver retinol (P < 0.05)
than did Sunvit A (P < 0.05) and Microvit A
DLC (P < 0.05). Control animals clearly had
decreased retinol concentrations in liver
compared to all vitamin A dietary supplements.

According to previous studies (Hammell et al.,
2000; McDowell, 2000), plasma retinol
concentration is a less reliable indicator of
vitamin A status than is liver retinol
concentration. Unless there is a severe
deficiency, the liver maintains relatively normal
plasma retinol concentrations. Our study
demonstrated large differences due to vitamin A
supplementation between treatments and control
in liver retinol concentrations, but only subtle
differences in plasma retinol. The liver is the
site for greatest storage of retinol and is the best
indicator of vitamin A status (McDowell, 2000).

Increasing the amount of vitamin A reaching the
duodenum increases the availability for
absorption and storage as is illustrated by
elevated liver retinol concentrations (Table 2).
Vitamin A availability is limited in ruminants
due to losses by ruminal destruction. Ruminal
destruction is especially high when ruminants
are fed high concentrate diets. Rode et al.
(1990) reported that in vitro ruminal microbial
degradation of vitamin A was 80% when the diet


2009 Florida BeefReport










contained 70% concentrate, whereas diets high
in forage only resulted in a 20% destruction of
vitamin A in vitro.

It was hypothesized that some vitamin A
supplements with protective coatings are more
resistant to rumen destruction or have improved
duodenal availability and that these would result
in greater liver concentrations of retinol. If these
coatings were resistant to intestinal digestion,
then supplemented vitamin A could pass the
duodenum, the site of vitamin A absorption, and
therefore be excreted. Certain products, like
Microvit A and Rovamix A, appear to have
better resistance to ruminal destruction or
improved duodenal availability than other
products tested in this experiment.


'Carlos Alosilla, Jr., Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist;
Charles Staples, Professor; William Thatcher, Professor; UF/IFAS, Department of Animal Sciences,
Gainesville, FL; Mike Blair, ADISSEO, Acworth, GA.


2009 Florida BeefReport


Literature Cited
Hammell et al. 2002. J. Dairy Sci. 22:1256.
McDowell. 2002. Vitamins in Animal and Human Nutrition. 2nd ed. Iowa State Press, Ames, IA.
Rode et al., 1990. Can. J. Anim. Sci. 70:227.











Table 1. Effect of vitamin A sources on plasma retinol concentrations of cattle
Microvit A SEM1
Item Control Microvit A Rovamix A Sunvit A Lutavit A
DLC
n 8 9 9 9 9 9
Pretrial plasma retinol, pg/mL
Day 0 0.329 0.365 0.333 0.310 0.297 0.329 0.0212

Covariate adjusted plasma retinol, pg/mL

Day 28 0.331ab 0.389a 0.381ab 0.321b 0.350ab 0.335ab
Day 28

Day 56 0.312ab 0.350a 0.365" 0.281b 0.339ab 0.345" 0.0103

Day 84 0.284 0.357ab 0.369 0.286 0.324abc 0.305b
Day 84
Overall mean 0.308b 0.366a 0.372a 0.296b 0.337ab 0.328ab 0.0174
a-c Treatments within the same row not bearing a common superscript differ (P < 0.05)
1Standard errors of the means (SEM) were the largest among treatments (i.e., for control).
2SEM for d 0.
3SEM for covariate adjusted day means.
4SEM for covariate adjusted overall means.


Table 2. Effect of vitamin A sources on liver retinol concentrations of cattle

Item Control Microvit A Rovamix A Sunvit A


Day 0


Lutavit A


Pretrial liver retinol, pg/g of wet liver

) 146 131 158

Covariate adjusted liver retinol, pg/g of wet liver


Day 28 121c 183a 153a 141b

Day 56 90C 178a 163ab 153ab

Day 84 70 187a 183a 143b

Overall mean 94 183a 166b 145b

a-c Treatments within the same row not bearing a common superscript differ (P < 0.05)
1 SEM were the largest among treatments (i.e., for control).
2 SEM for d O.
3 SEM for covariate adjusted day means.
4 SEM for covariate adjusted overall means.


Microvit A
DLC

9



151



158b

135b

156ab


SEM'


2009 Florida BeefReport


161a"

151ab

168ab




Full Text

PAGE 1

Bioavailability of Vitamin A (Retinol) Sources for Cattle Carlos Alosilla, Jr. 1 Lee McDowell Nancy Wilkinson Charles Staples William Thatcher Michael Blair Summary An experiment was conducted to evaluate bioavailability of five sources of vitamin A (retinol). Fifty-three yearling Angus Brahman cattle, consisting of 39 steers and 14 heifers, were stratified by BW and gender and randomly assigned to six high concentrate diet groups receiving either no vitamin A supplementation (control), or vitamin A supplemented from the following sources: Microvit A (ADISSEO, Acworth, GA), Rovamix A (DSM, Parsippany, NJ), Sunvit A, Lutavit A, and Microvit A DLC (ADISSEO). Vitamin A treatment groups were fed daily 80,000 IU retinol/animal in a low retinol concentrate diet (78.5% oats, 10% cottonseed hulls, 8% molasses, and 2% cottonseed meal) for 84 d. Every 28 d body weight was determined and liver biopsies and plasma were collected and analyzed for retinol concentrations. All retinol treatments showed significant increases in liver retinol concentrations compared to control animals (P < 0.0001), which steadily decreased over time. At all collection times, Microvit A led to numerically greater concentrations of retinol in liver than did all other treatments. However, at experiment termination, there was no significant difference in liver retinol concentration among Microvit A, Rovamix A, Lutavit A, and Microvit A DLC diets. When liver retinol concentrations at all collection times were considered, Microvit A and Rovamix A appeared to provide the most bioavailable vitamin A. Introduction Vitamin A generally is supplemented to ruminant diets to insure maximum health and productivity. Unfortunately, considerable supplemental retinol is destroyed by ruminal microbes. The amount of concentrate in a diet is one factor associated with ruminal destruction. Rode et al. (1990) reported an 80% loss of vitamin A when cattle were fed 70% concentrate diets, but, when fed high-forage diets, losses were only 20%. There is a need for minimizing ruminal destruction to increase the amount of vitamin A that reaches the duodenum. In order to protect vitamin A from pre-intestinal destruction, gelatin beadlets have been developed commercially that contain not only vitamin A but also carbohydrates and antioxidants to stabilize the vitamin A. The objective of this study was to compare the bioavailability of five different forms of supplemental vitamin A fed to beef cattle. Procedure Fifty-three yearling Angus Brahman cattle, consisting of 39 steers and 14 heifers, that Vitamin A destruction occurs in the rumen with retinol losses up to 80%. For the sources of vitamin A studied Microvit A and Rovamix A appear to be more available to cattle.

PAGE 2

weighed 750.2 44 lbs, were stratified by gender and BW and assigned randomly to one of seven pens and one of eight Calan gates (American Calan, Northwood, NH) within pens at the University of Florida Beef Research Unit in August of 2002. High concentrate dietary treatments included 78.5% oats, 10% cottonseed hulls, 8% molasses, and 2% cottonseed meal. Experimental treatments were control (no supplemental vitamin A), Microvit A (ADISSEO, Acworth, GA), Rovamix A (DSM, Parsippany, NJ), Sunvit A, Lutavit A, and Microvit A DLC (ADISSEO) fed daily at 80,000 IU/animal. Vitamin A pre-mixes were formulated and mixed every two wk. Feed intake gradually increased, therefore vitamin A additions changed so that cattle always received 80,000 IU/d. A total of nine cattle were used per treatment except for eight in the control group. In each pen, poor quality Bermuda grass hay -carotene/g) and water were supplied for ad libitum consumption. On d 0, 28, 56, and 84, all animals were restrained and weighed, and liver biopsy and blood samples were collected. Vitamin A was analyzed by a standardized HPLC system. The experiment was a completely random design. All data were analyzed using the Mixed Procedure of SAS (SAS for Windows 8e; SAS Institute, Inc., Cary, NC) for repeated measures. The model included terms for a covariate (value from d 0), treatment, time, and treatment time. Results Body weights increased with time ( P < 0.0001), but there were no effects of treatment ( P = 0.86) or of treatment x time ( P = 0.31) detected. As there were no differences among treatments, control cattle with minimal dietary vitamin A were able to rely on storage reserves of retinol for body growth. Retinol concentrations in plasma (Table 1) were affected by treatment ( P = 0.01) and time ( P = 0.04). There were no interactions between treatment and time ( P = 0.96). Using d 0 values as the covariate, both Microvit A and Rovamix A increased ( P < 0.05) plasma retinol (d 84 and overall) compared to control and also compared to the Sunvit A treatment groups ( P < 0.05). On d 84, both Lutavit A and Microvit A DLC were intermediate and did not differ from control; Lutavit A also did not differ from Microvit A or Rovamix A, and Microvit A DLC did not differ from Microvit A. Similar trends at d 28 and d 56 were evident. Retinol concentrations in liver (Table 2) were affected by treatment ( P < 0.01) and a treatment x time interaction was detected (P < 0.0001); retinol-supplemented cattle had greater ( P < 0.05) and more sustained concentrations of liver retinol compared to a steady decline for the control group through d 84 (Table 2). Overall Microvit A had the numerically highest concentration of liver retinol, but it did not differ statistically from Rovamix A and Lutavit A. However, averaged over all sampling times, Microvit A led to greater liver retinol ( P < 0.05) than did Sunvit A ( P < 0.05) and Microvit A DLC ( P < 0.05). Control animals clearly had decreased retinol concentrations in liver compared to all vitamin A dietary supplements. According to previous studies (Hammell et al., 2000; McDowell, 2000), plasma retinol concentration is a less reliable indicator of vitamin A status than is liver retinol concentration. Unless there is a severe deficiency, the liver maintains relatively normal plasma retinol concentrations. Our study demonstrated large differences due to vitamin A supplementation between treatments and control in liver retinol concentrations, but only subtle differences in plasma retinol. The liver is the site for greatest storage of retinol and is the best indicator of vitamin A status (McDowell, 2000). Increasing the amount of vitamin A reaching the duodenum increases the availability for absorption and storage as is illustrated by elevated liver retinol concentrations (Table 2). Vitamin A availability is limited in ruminants due to losses by ruminal destruction. Ruminal destruction is especially high when ruminants are fed high concentrate diets. Rode et al. (1990) reported that in vitro ruminal microbial degradation of vitamin A was 80% when the diet

PAGE 3

contained 70% concentrate, whereas diets high in forage only resulted in a 20% destruction of vitamin A in vitro. It was hypothesized that some vitamin A supplements with protective coatings are more resistant to rumen destruction or have improved duodenal availability and that these would result in greater liver concentrations of retinol. If these coatings were resistant to intestinal digestion, then supplemented vitamin A could pass the duodenum, the site of vitamin A absorption, and therefore be excreted. Certain products, like Microvit A and Rovamix A, appear to have better resistance to ruminal destruction or improved duodenal availability than other products tested in this experiment. Literature Cited Hammell et al. 2002. J. Dairy Sci. 22:1256. McDowell. 2002. Vitamins in Animal and Human Nutrition. 2 nd ed. Iowa State Press, Ames, IA. Rode et al., 1990. Can. J. Anim. Sci. 70:22 7. 1 Carlos Alosilla, Jr., Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist; Charles Staples, Professor; William Thatcher, Professor; UF/IFAS, Department of Animal Sciences, Gainesville, FL; Mike Blair, ADISSEO, Acworth, GA.

PAGE 4

Table 1. Effect of vitamin A sources on plasma retinol concentrations of cattle Item Control Microvit A Rovamix A Sunvit A Lutavit A Microvit A DLC SEM 1 n 8 9 9 9 9 9 Pretrial plasma retinol, g/mL Day 0 0.329 0.365 0.333 0.310 0.297 0.329 0.021 2 Covariate adjusted plasma retinol, g/mL Day 28 0.331 ab 0.389 a 0.381 ab 0.321 b 0.350 ab 0.335 ab Day 56 0.312 ab 0.350 a 0.365 a 0.281 b 0.339 ab 0.345 a 0.010 3 Day 84 0.284 c 0.357 ab 0.369 a 0.286 c 0.324 abc 0.305 bc Overall mean 0.308 b 0.366 a 0.372 a 0.296 b 0.337 ab 0.328 ab 0.017 4 a c Treatments within the same row not bearing a common superscript differ ( P 1 Standard errors of the means (SEM) were the largest among treatments (i.e., for control). 2 SEM for d 0. 3 SEM for covariate adjusted day me ans. 4 SEM for covariate adjusted overall means. Table 2. Effect of vitamin A sources on liver retinol concentrations of cattle Item Control Microvit A Rovamix A Sunvit A Lutavit A Microvit A DLC SEM 1 n 8 9 9 9 9 9 Pretrial liver retinol, g/g of wet liver Day 0 158 160 146 131 158 151 27 2 Covariate adjusted liver retinol, g/g of wet liver Day 28 121 c 183 a 153 ab 141 bc 161 ab 158 ab Day 56 90 c 178 a 163 ab 153 ab 151 ab 135 b 5 3 Day 84 70 c 187 a 183 a 143 b 168 ab 156 ab Overall mean 94 c 183 a 166 ab 145 b 160 ab 150 b 10 4 a c Treatments within the same row not bearing a common superscript differ ( P 1 SEM were the largest among treatments (i.e., for control). 2 SEM for d 0. 3 SEM for covariate adjusted day means. 4 SEM for covariate adjusted overall means.