Chromium as an animal feed supplement

Chromium, preferably in the form of chromium propionate, is used as an animal feed supplement. The addition of chromium to a diet containing a balanced level of dietary energy results in an increase in animal growth performance relative to the level of dietary energy and/or improved meat quality.

BACKGROUND OF THE INVENTION
 1. Field of Invention
 This invention relates to a chromium supplement for animals. More
 particularly, the present invention relates to the supplementation to
 animals, particularly mammals or birds, of chromium as chromium
 propionate. The present invention specifically relates to the addition of
 chromium propionate to a diet containing a balanced level of dietary
 energy that results in an increase in average daily gain relative to the
 level of dietary energy and/or improved meat quality.
 2. Background of the Prior Art
 Chromium is a trace element. This trace element has been identified as a
 glucose tolerance factor and appears to facilitate this action of insulin
 in a number of animals and humans. Recent research has shown that chromium
 supplementation in pigs(Amoikon, E. K., J. M. Fernandez, L. L. Southern,
 D. L. Thompson, Jr., T. L. Ward and B. M. Olcott. 1995. Effect of chromium
 tripicolinate on growth, glucose tolerance, insulin sensitivity, plasma
 metabolites, and growth hormone in pigs. J. Anim. Sci. 73:1123.), lambs
 lambs (Kitchalong, L., J. M. Fernandez, L. D. Bunting, A. M. Chapa, L. S.
 Sticker, E. K. Amoikon, T. L. Ward, T. D. Bidner, and L. L. Southern.
 1993. Chromium picolinate supplementation in lamb rations: Effects on
 performance, nitrogen balance, endocrine and metabolic parameters. J.
 Anim. Sci. 71(Suppl. 1):291 (Abstr.)), and calves(Bunting, L. D., J. M.
 Fernandez, D. L. Thompson, Jr., and L. L. Southern. 1994. Influence of
 chromium picolinate on glucose usage and metabolic criteria in growing
 Holstein calves. J. Anim. Sci. 72:1591.) increases the glucose
 disappearance rate and decreases the glucose half-life. The form that the
 chromium is administered in, organic or inorganic, appears to change the
 magnitude of the mammals' response, with the better result coming from
 certain organic forms of chromium. The best bioavailability results appear
 to be from chromium picolinate, with less bioavailability in chromium rich
 yeast.
 Chromium has been linked to the metabolism of lipids, and protein. Chromium
 decreases serum triglycerides and increases high density lipoproteins. In
 rabbits, testing has shown that chromium decreases cholesterol and assists
 in removal of deposited cholesterol (Yamamoto, A., O. Wanda and S. Manabe.
 1989. Evidence that chromium is an essential factor for biological
 activity of low-molecular weight, chromium-binding substance. Biochem.
 Biophys. Res. Commun. 163:189-193).
 Inconsistent responses in both biological and performance animal testing,
 relative to the cost of supplementation, have prevented wide acceptance of
 dietary chromium. Suggested causes for such inconsistencies include the
 level and bioavailability of chromium naturally occurring in feed
 ingredients, duration of feeding and the historical chromium status of the
 pig (NRC. 1998. Nutrient requirements of swine (10.sup.th Ed.). 1998.
 National Academy Press, Washington, D.C.). Additionally, dietary amino
 acid levels may also affect the animal's response to chromium (White, M.,
 J. Pettigrew, J. Zollitsch-Stelzl, and B. Crooker. 1993. Chromium in swine
 diets. Pp. 251-261 in Proceedings of the 54.sup.th Minnesota Nutrition
 Conference and National Renderers Technical Symposium; Lindemann, M. D.,
 C. M. Wood, A. F. Harper, E. T. Komegay, and R. A. Anderson. 1995b.
 Dietary chromium picolinate additions improve gain:feed and carcass
 characteristics in growing-finishing pigs and increase litter size in
 reproducing sows. J. Anim. Sci. 73:457-465). A recent study demonstrated
 that the chemical form of supplemental chromium may play a role in at
 least the level of animal response measured (Matthews, J. O., L. L.
 Southern, J. M. Fernandez, A. M. Chapa, L. R. Gentry and T. D. Binder.
 1997. Effects of dietary chromium tripicolinate or chromium propionate on
 growth, plasma metabolites, glucose tolerance, and insulin sensitivity in
 pigs. J. Anim. Sci. 75 (Suppl. 1): 187 (Abstr.)). That study measured
 plasma metabolites, hormones, glucose tolerance and insulin sensitivity
 when pigs were supplemented with 200-ppb of either chromium picolinate or
 chromium propionate (in the form of KemTRACE.RTM. Chromium, a source of
 chromium propionate available commercially from Kemin Industries, Inc.,
 Des Moines, Iowa) (U.S. Pat. No. 5,846,581).
 Research specifically addressing the effects of chromium on pork (meat)
 quality is limited. Boleman (Boleman, S. L., S. J. Boleman, T. D. Bidner,
 T. L. Ward, L. L. Southern, J. E. Pontif and M. M. Pike. 1995. Effect of
 chromium picolinate on growth, body composition, and tissue accretion in
 pigs. J. Anim. Sci. 73:2033-2042) reported no response to water holding
 capacity (purge loss) or firmness/wetness sensory criteria to chromium
 from chromium picolinate, however shear force was increased by chromium
 treatment. More recently, a study at Kansas State University (O'Quinn, P.
 R., J. W. Smith, II, J. L. Neissen, M. D. Tokach, R. D. Goodband, and K.
 Q. Owen. 1998. Effects of source and level of added chromium on growth
 performance and carcass characteristics of growing-finishing pigs. J.
 Anim. Sci. 76 (Suppl. 2): 56 (Abstr.)) demonstrated both positive and
 negative responses to pork quality criteria in gilts, but little or no
 response in barrows, when fed chromium from either chromium nicotinate or
 chromium picolinate. Specifically, a reduction of visual color of the
 longisimuss dorsi muscle and saturation index (quadratic, P=0.09 and
 P=0.05, respectively) of gilts with increasing levels of chromium (0,
 50,100, 200 and 400-ppb) from chromium nicotinate. The visual color of the
 longisimuss dorsi from gilts fed 200-ppb chromium from chromium nicotinate
 was lower (P=0.05) than from those fed 200-ppb from chromium picolinate,
 however chromium picolinate offered no response (P&gt;0.15) to visual
 color compared to unsupplemented pigs. Also, gilts fed 200-ppb chromium
 from chromium picolinate had less (P=0.02) marbling (2.58 vs. 2.88%), but
 reduced (P=0.08) drip loss percentage (2.04 vs. 2.19%) compared to the
 controls. Although not significant, barrows fed 200-ppb chromium from
 chromium picolinate had numerically reduced (P&gt;0.15) marbling (2.63 vs.
 2.72%) and greater drip loss (3.73 vs. 3.33%) compared to barrows fed the
 control diet.
 Likewise, research specifically addressing chromium and its potential
 interaction with dietary energy levels is limited. However, a recent study
 at the University of Kentucky (van de Ligt, C. P. A., M. D. Lindemann, and
 G. L. Cromwell. 1998. Assessment of chromium picolinate addition and
 dietary energy levels on performance of growing pigs. J. Anim. Sci. 76
 (Suppl 1): 159 (Abstr.)) measured no effect from chromium from chromium
 picolinate or chromium.times.metabolizable energy (Cr.times.ME)
 concentration on the performance or carcass characteristics of growing
 (from 25.4 to 70.1 kg) PIC barrows.
 Chromium in the form of chromium picolinate has been reported to increase
 swine production (Lindemann, M. D., C. M. Wood, A. F. Harper, E. T.
 Komegay, and R. A. Anderson. 1995b. Dietary chromium picolinate additions
 improve gain:feed and carcass characteristics in growing-finishing pigs
 and increase litter size in reproducing sows. J. Anim. Sci. 73:457-465).
 Chromium picolinate has been shown in U.S. Pat. No. 5,336,672 to increase
 egg production in poultry that have been supplemented with this type of
 chromium. Additionally, the effects of chromium picolinate and chromium
 chloride on various mammals have been studied. These effects include the
 growth and carcass traits and plasma metabolites of pigs (Ward, T. L., L.
 L. Southern, and R. A. Anderson. 1995. Effect of dietary chromium source
 on growth, carcass characteristics, and plasma metabolite and hormone
 concentrations in growing-finishing swine. J. Anim. Sci. 73 (Suppl 1): 189
 (Abstr.)), the effects on performance and nitrogen balance and endocrine
 in lambs (Kitchalong et al., 1993), essential role of chromium in
 ruminants (Samsell, L. J. 1987. Studies on possible essential roles of
 chromium in the ruminate. M. S. Thesis. North Carolina State Univ.
 Raleigh, N.C.), and the effects of chromium in egg cholesterol and egg fat
 and egg protein in poultry.
 There has been no prior reference that has suggested that providing
 chromium in the form of chromium propionate as a supplement to an energy
 balanced diet would increase the mammals production characteristics beyond
 that of chromium picolinate. In fact, the suggestions in the literature
 have been the opposite, since metal picolinates have been suggested to
 make metals more biologically available for absorption than other organic
 acids. U.S. Pat. No. 4,315,927 (1982).
 In an insulin challenge test (IVICT), glucose clearance increased
 (P&lt;0.02) in pigs fed KemTRACE.RTM. Chromium and tended to increase
 (P&lt;0.12) in pigs fed chromium picolinate, with the glucose clearance in
 the KemTRACE.RTM. Chromium group increasing 18% over pigs fed chromium
 picolinate, and 45% over the control pigs not receiving chromium
 supplementation. Similarly, glucose half-life (t.sub.1/2) was reduced
 (P&lt;0.03) by 23% and 35% for the chromium picolinate and KemTRACE.RTM.
 Chromium treatments, respectively, when compared to the non-supplemented
 pigs. Matthews, J. O., L. L. Southern, J. M. Fernandez, A. M. Chapa, L. R.
 Gentry and T. D. Binder. 1997. Effects of dietary chromium tripicolinate
 or chromium propionate on growth, plasma metabolites, glucose tolerance,
 and insulin sensitivity in pigs. J. Anim. Sci. 75 (Suppl. 1): 187 (Abstr.)
 An object of this invention is to provide a feed additive, chromium
 propionate, that increases the average daily gain of the animal while
 maintaining or reducing the dietary energy level in the diet of the
 animal.
 Another object of this invention is to provide a feed additive that
 improves the meat quality of the animal, through increased marbling,
 reduced moisture in muscle tissue, reduced purge/drip loss, and/or
 improved firmness/wetness scores.
 A further object of this invention is to provide a feed additive to a less
 energy dense feed such that the average daily gain of the mammal is
 maintained on a less expensive feed.
 SUMMARY OF THE INVENTION
 This invention relates to the use of chromium propionate as a feed
 supplement for mammals and birds. The invention provides a chromium
 supplement formed as chromium propionate which is balanced with the
 dietary energy level of the diet of the animal to improve the relative
 performance of the animal. More specifically, the invention provides a
 chromium supplement formed as chromium propionate which when fed to pigs
 allows the use of a diet with decreased metabolizable energy while
 maintaining the performance of the animal. Alternatively, the invention
 provides a chromium supplement formed as chromium propionate which when
 fed to pigs allows the use of a diet with increased metabolizable energy
 which results in improving the performance of the animal.
 The present invention includes the use of chromium propionate as an animal
 dietary supplement to improve the quality of meat of the animal.
 Specifically, chromium treatment using chromium propionate results in
 significant pork quality responses in pigs fed either low- or
 high-metabolizable energy diets. Positively affected are increased
 marbling, reduced moisture in the longisimuss dorsi (LD) muscle, and
 reduced purge/drip loss. In addition, chromium propionate supplementation
 tends to improve firmness/wetness scores in both low- or
 high-metabolizable energy diets.
 The present invention includes a method of increasing or maintaining the
 animal's growth performance while balancing the dietary energy content of
 the diet. The steps of this method include the steps of balancing the
 increased energy density of the diet with the amount of chromium
 propionate supplied to an animal wherein the animal's growth performance
 is increased or maintained. Increasing the dietary oil or fat content of
 the feed can increase the energy density of the diet, while decreasing the
 oil or fat content or substituting lower energy feedstuffs will decrease
 the metabolizable energy of the diet.
 Supplementation with chromium propionate while increasing dietary energy
 concentration may lower daily feed intake of an animal which is beneficial
 provided the animal's growth performance is maintained. Supplementation
 with chromium propionate while decreasing dietary energy concentration
 resulting from using a lower fat and oil content and/or lower energy
 feedstuffs, is a method of decreasing the cost of an animal diet while
 maintaining or improving the performance of the animal. Supplementation
 with chromium propionate at low- and high-dietary energy levels improves
 the meat quality of the animal.