© 2002 The American Society for Nutritional Sciences
J. Nutr. 132:1774S-1775S, June 2002
Supplement: Waltham International Symposium
Serum Response of Ponies to ß-Carotene Fed by Grass Meal or a Synthetic Beadlet Preparation with and without Added Dietary Fat
Ellen Kienzle3,
Christine Kaden,
Peter P. Hoppe* and
Birgit Opitz
Institute of Physiology, Biochemistry and Animal Nutrition, Ludwig-Maximilians-University Munich, Munich, Germany and
* Nutrition Research BASF, Offenbach, Germany
3To whom correspondence should be addressed. E-mail: kienzle{at}tiph.vetmed.uni-muenchen.de.
KEY WORDS: • symposium • ß-carotene • horses • bioavailability
EXPANDED ABSTRACT
ß-Carotene as a feed additive has been added to diets for horses because of potential effects on ovarian function. It was suggested that ß-carotene might replace vitamin A as an additive in high-quality concentrate mixtures for horses to avoid excessive vitamin A intake when horses eat large quantities of such concentrates. Two working groups using a water-dispersible ß-carotene preparation found negligible absorption, and consequently no effect on vitamin A status (1,2). However, others (3,4) reported evidence for the bioavailability of ß-carotene as a feed additive. In our study we compared the serum response to ß-carotene from a synthetic beadlet preparation (LucarotinTM; BASF, Ludwigshafen, Germany) and from grass meal. Both carotene sources were fed with and without added sunflower oil.
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MATERIALS AND METHODS
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Four adult ponies (222–345 kg body weight) were fed a diet that was practically free of ß-carotene for 3 mo (washout period, Table 1). Thereafter, each pony received in a 4 x 4 Latin square design each of four dietary treatments containing ß-carotene, either from grass meal or from the synthetic preparation, with or without sunflower oil. The study was approved by the Regierung von Oberbayern, which is the appropriate authority in Munich, according to German laws on animal welfare (Deutsches Tierschutzgesetz). The diets were designated: grass meal, grass meal/oil, beadlet and beadlet/oil (Table 1), and given to the horses for 4 wk. Each diet was followed by a washout period of 4 wk before the ponies were rotated to the next diet. Blood samples were taken (jugular vein, 2.5 h after the morning feeding) at wk 1 and wk 4 of each trial and of each washout period. Serum was prepared (avoiding exposure to light) and stored at -20°C until analyzed by the method described elsewhere (5,6). Briefly, samples were saponified, extracted under nitrogen and taken up in n-hexane:dioxane (100:1, v/v) as the mobile phase. Separation was by HPLC using a Lichrosorb SI 60 column and a UVIS detector set at 436 nm. Serum triglycerides were analyzed by the GPO-PAP method and cholesterol by the SCHOD-PAP method using a Hitachi 717 autoanalyzer (Merck-Hitachi, Darmstadt, Germany). Results were tested for homogeneity and analyzed by repeated-measures analysis (Proc GLM; SAS Institute, Cary, NC). Means and SEM were calculated. Analysis of variance did not indicate any significant differences (P < 0.05) or interactions between the different experimental periods. Therefore only comparisons of two means were required, such as comparisons between the means of each experimental period and its preceding washout period. Two means were compared by a paired t-test (P < 0.05 was considered a significant difference).
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RESULTS AND DISCUSSION
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The serum ß-carotene concentrations at the end of each treatment and the preceding washout periods are presented in Figure 1. The serum levels were significantly higher during the treatment periods than during the washout periods; however, there were no significant effects of the source of carotene or the inclusion of sunflower oil. The significant response to ß-carotene was apparent after 1 wk of feeding (results not shown). The addition of oil led to a reduction in serum cholesterol from 3.24 ± 0.28 to 2.33 ± 0.13 mmol/L. There was a similar tendency in serum triglycerides with oil, but the difference was not significant (0.48 ± 0.14 mmol/L without oil; 0.38 ± 0.10 mmol/L with oil addition).
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FIGURE 1 Mean ± SEM serum ß-carotene concentrations in four ponies following intake of grass meal or beadlets as sources of ß-carotene. The washout period applies to the preceding treatment period. All differences between experimental and washout periods were significant (P < 0.05).
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The similar increase in serum ß-carotene concentration demonstrates that both sources of ß-carotene were bioavailable, and there was no difference in the efficiency of absorption of ß-carotene from either source. This observation supports the work of Eitzer and Rapp (3) and Klemt (4), who used synthetic beadlet preparations. However, it is at variance with the results of Watson et al. (1) and Greiwe-Crandell et al. (2), who reported that water-dispersible beadlet preparations, which are generally considered of high bioavailability, did not result in an elevation of plasma concentration. These discrepant findings cannot be explained. However, they may relate to the rapid rate of passage of water and water-soluble nutrients through the stomach and the small intestine of the horse. According to Mueller (7), the prececal passage of water can be as short as 0.5 h. This might not allow sufficient time to absorb significant amounts of ß-carotene from water-dispersible preparations.
In our study there was no effect of oil on the ß-carotene response of serum, an observation in agreement with that of other investigators (8). It appears that the crude fat content in normal horse feeds (about 2 g/kg dry matter) is sufficient to mediate ß-carotene absorption. On the other hand effects of oil in facilitating the transfer of ß-carotene to micelles and effects on plasma lipids may lead to a net result of unchanged serum levels of ß-carotene.
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FOOTNOTES
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1 Presented as part of the Waltham International Symposium: Pet Nutrition Coming of Age held in Vancouver, Canada, August 6–7, 2001. This symposium and the publication of symposium proceedings were sponsored by the Waltham Centre for Pet Nutrition. Guest editors for this supplement were James G. Morris, University of California, Davis, Ivan H. Burger, consultant to Mars UK Limited, Carl L. Keen, University of California, Davis, and D’Ann Finley, University of California, Davis. 
2 Supported by BASF, Offenbach, Germany.
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LITERATURE CITED
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1. Watson, E. D., Cuddeford, D. & Burger, I. (1996) Failure of ß-carotene absorption negates any potential effect on ovarian function in mares. Equine Vet. J. 28:233-236.
2. Greiwe-Crandell, K. M., Kronfeld, D. S., Gay, L. S., Sklan, D., Tiegs, W. & Harris, P. A. (1997) Vitamin A repletion in thoroughbred mares with retinyl palmitate or beta-carotene. J. Anim. Sci. 75:2684-2690.[Abstract/Free Full Text]
3. Eitzer, P. & Rapp, H. J. (1985) Zur oralen Anwendung von synthetischem ß-Carotin bei Zuchtstuten (Oral application of synthetic ß-carotene in brood mares). Prakt. Tierarzt. 66:123-128.
4. Klemt, P. W. (1986) Auswirkungen einer Zufütterung von synthetischem ß-Carotin auf das postpartale Fruchtbarkeitsgeschehen von Zuchtstuten anhand von Progesteronprofilen aus der Milch (Effect of supplementation of synthetic ß-carotene on postpartal fertility in brood mares as indicated by progesterone profiles in milk). Ph.D. Dissertation 1986 Ludwig-Maximilians-Universität Munich, Germany.
5. Hoppe, P. P., Schöner, F. J., Wiesche, H., Stahler-Geyer, A., Kammer, J. & Hochadel, H. (1993) Effect of graded 
-tocopherol supplementation on concentration in plasma and selected tissues of pigs from weaning to slaughter. J. Vet. Med. Ser. A 40:219-228.
6. Chew, B. P., Wong, T. S. & Michal, J. J. (1993) Uptake of orally administered ß-carotene by blood plasma, leucocytes, and lymphocytes in calves. J. Anim. Sci. 71:730-739.[Abstract]
7. Müller, L. F. (1951) Die Bewegungserscheinungen am Darm des Pferdes (Motility of the horse gut) 1951 Habilitationsschrift (Thesis) Vet.med. Fakultät Leipzig, Germany.
8. Zeyner, A., Buchholz, H. & Schweigert, F. J. (1995) Untersuchungen zum Einfluß von Fettgaben auf die Konzentration an ß-Carotin, Vitamin A und E im Blutserum von Pferden (Investigations on the effect of fat addition on the serum concentration of ß-carotene, vitamin A and E in horses). Vitamine und Zusatzstoffe bei Mensch und Tier, 5, Symposium, Jena, Germany, 1995, pp. 97–100.
9. Gesellschaft für Ernährungsphysiologie der Haustiere (GEH) (1994) Empfehlungen zur Energie- und Nährstoffversorgung des Pferdes (Recommendations on energy and nutrient supply of horses) 1994 DLG-Verlag Frankfurt/Main, Germany.
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