Chromium Picolinate Reduces Laying Hen Serum and Egg Yolk Cholesterol

The Professional Animal Scientist 12: 77-80

ttrI Chromium Picolinate Reduces Laying Hen Serum and Egg Yolk Cholesterol TU-FA L1EN*, SHIH-YI CHEN*, SHING-PUU SHIAU*,l, DAVID P. FROMANt, and CHING YUAN HUtl

*Department of Animal Science, National Chiayi Institute of Agriculture, Chiayi, Taiwan, R.O.C., and tDepartment of Animal Sciences, Oregon State University, Corvallis, OR 97331-6702

Abstract One hundred 55-wk-old Single Comb White Leghorn hens were divided randomly into four experimental groups. Hens were caged individually. Each treatment group was fed one of four experimental diets for 35 consecutive d. The control diet was a standard layer ration. The other diets were supplemented with chromium picolinate at 200,400, or 800 JIg/kg. The objective of the experiment was to determine the effect of chromium picolinate on egg production, egg quality, and serum traits. Dietary supplementation with chromium picolinate had no effect on egg production and a negligible effect on egg weight. In contrast, chromium picolinate lowered (p<0.05) the concentration of egg yolk cholesterol in a dose-response manner. However, shell strength was reduced (p<0.05) by 30% at the highest dose. At 800 ppb chromium picolinate reduced (p<0.05) total serum cholesterol by 39%. Although LDL-cholesterol and apolipoprotein (Apo) B was reduced at this dose, HDL-cholesterol and Apo A-l

lTo whom correspondence should be addressed. Reviewed by R. E. Buresh and ]. L. MorrowTesch. Sponsored by D. W. Weber.

activity and metabolism of chromium depends on its chelated form (15). Mertz (15) deSignated an organic form of chromium found in brewer's yeast as a glucose tolerance factor. Subsequent studies (13, 20) have shown that the organiC form of chromium is superior to the inorganiC form of chromium. Chromium picolinate has been shown to reduce (Key Words: Chromium, Picolinic body fat and increase muscle in ACid, Layer, Egg, Cholesterol.) humans and swine (I, 7, 20). It has also been shown to lower the serum concentrations of glucose, lipid, and Trivalent chromium has important total cholesterol (7, 20). Gibson (8) showed that many plant products physiological functions in humans contain low levels of chromium, and (I), rats (14), cattle (17), swine (20, 23) and poultry (21, 24). Chromium milling removes about 83% of a defidency results in retarded growth, grain's original chromium. Moreover, only 1.5% of ingested chroinsulin resistance, impaired glucose tolerance, hypercholesterolemia, and mium is actually absorbed. Therefore, commercial layer rations may be hyperlipidemia. Such conditions deficient in biologically available have been ameliorated by supplechromium. Furthermore, in view of menting dietary chromium (25). the relationship between dietary Therefore, chromium has been chromium and serum cholesterol, we considered as an essential trace found a possible relationship bemineral in humans and animals. tween dietary chromium and egg In animal trials when inorganic chromium chloride was the source of yolk cholesterol intriguing. Therefore, the objective of this study was dietary chromium, limited benefits were observed (II, 23, 24). However, to determine the effect of chromium picolinate on egg production, egg such results may have been due to quality, and serum traits. the fact that chromium chloride is poorly absorbed (19). Biological

increased and serum triglyceride was reduced. These results demonstrate that supplementing a layer ration with chromium picolinate alters lipid profiles in serum and lowers cholesterol content of the yolk, but does not affect egg production.

Introduction

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Materials and Methods

Lien et al.

mium picolinate was premixed with cornstarch prior to admixture with other ingredients. Each hen was fed Each of 100 Single Comb White Leghorn laying hens was assigned 100 g of its respective ration per d . Water was available for ad libitum randomly to one of four treatments. Hens were 55 wk of age at the begin- consumption throughout the 35-d ning of the experiment and had been experimental period. fed a commercial layer diet. Hens Egg production was recorded daily were caged individually (35 cm x 24 for each hen. Eggs collected on d 0 cm x 37 cm) . Treatments were as and 35 were used for the following follows : a control diet (Table I), or analyses: egg weight, shell breaking control diet supplemented with 200, strength, shell thickness, Haugh units (a measure of the height of the 400, or 800 ppb of chromium in the form of chromium picolinate. Chro- albumen after correcting the reading for difference in egg size), and yolk cholesterol concentration. Yolk TABLE 1. Composition of basal cholesterol concentration was deterdiet. mined by first homogenizing an entire yolk, and then mixing 0.5 ml Ingredients Percentage of the homogenate with 5 ml of 2% (wt/vol) KOH-alcohol. This mixture Yellow corn meal 57.87 was incubated at 50°C in a shaking Soybean meal 24.00 water bath (100 strokes per minute) Fish meal 3.00 for 1 h. After cooling to room Soybean oil 2.98 temperature, 10 ml of petroleum 1.30 Dicalcium phosphate ether was added, and the resultant 7.72 Limestone, pulverized mixture was centrifuged according to Iodized salt 0.30 Beyer and Jensen (5). The cholesterol DL-Methionine 0.08 Vitamin premix a 0.05 concentration of the supernatant was Mineral premix b 0.20 determined by an enzymatic kit (Roche Co. No. 07-36635) using an 100.00 Total automatic serum biological analyzer. Control serum provided by the Calculated value vendor (Roche Co. No. 07-37194) 17.80 Crude protein, % was used to establish the reference 2840.00 ME, kcal/kg curve. Calcium, % 3.40 Blood samples were obtained by Available phosphorus, % 0.47 cardiac puncture on d 0 and 35 . The Analyzed value following variables were measured in Crude protein, % 17.90 serum: total cholesterol, high density Calcium, % 3.39 lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDLaVitamin premix supplied the following C), apolipoprotein A-I (Apo A-I), per kilogram of diet: vitamin A, 25,000 apolipoprotein B (Apo B), and IU; cholecalciferol, 3125 IU; vitamin E, triglyceride (TG) concentration. 37.5 IU; vitam in K3, 6.25 mg; vitamin Total cholesterol and TG were anaB" 3.85 mg; vitamin B2, 12.5 mg; lyzed by a colorimetric method using vitamin B6 , 10.0 mg; pantothenate, an automatic serum biochemical 18.8 mg; niacin, 50 mg; biotin, 0.06 analyzer (Roche Co.). The HDL-C mg; fol ic acid, 1.25 mg; vitamin B'2' was assayed by phosphotungstic 0.05 mg. acid/magnesium chloride method bMineral premix supplied the following per kilg ram of diet: Cu (CuS0 4 ,5H2 0, (26) . The LDL-C was determined as 25,45% Cu) 6 mg; Fe (FeS0 4 ,7Hp, follows . One milliliter of serum was 20.09% Fe) 50 mg; Mn (Mn S0 4,H20, mixed with 4.5 ml of 0 .85% KBr and 32.49% M n) 40 mg; Zn (Zn, 80.35% 0 .1% sodium EDTA (d = 1.0063) . In) 60 mg; Se (NaSe0 3, 45 .56% Se) This mixture was centrifuge d at 0.075 mg. 100,000 x g for 8 h at 20°C in a

Beckman 40.2 rotor. Those fraction s with a density greater than 1.0063, which contained a mixture of LDL and HDL, were used for cholesterol assay (4) . The LDL-C concentration was calculated as the difference between the observed value and that observed for HDL-C. Apolipoprotein Band Apo A were each measured turbidimetrically (6) following precipitation with specific antibodies (Roche Co., Nos. 07-29957 and 0729949) . Analyses of covariance were performed using the General Linear Models procedure (22), and individual treatment differences were determined by Duncan's multiple range test.

Results and Discussion Supplementing a layer ration with chromium picolinate did not affect egg production (Table 2) . Whereas egg weight was reduced by 12% (P<0.05) in the 200 ppb treatment group, egg weights at higher doses were not different from the control. Thus, there was no dose effect on egg weight. Yolk weight also was not affected by the treatment. In contrast, eggshell breaking strength was reduced (P<0.05) by approximately 32% with the two highest doses of chromium picolinate (Table 2) . Because shell thickness did not appear to be affected by chromium picolinate supplementation (Table 2), the basis for decreased eggshell breaking strength was not apparent. As evidenced by Haugh units (Table 2), chromium picolinate supplementation did not adversely affect albumen quality. Jensen and Maurice (10) showed that 5 ppm chromium chloride also did not affect interior egg quality. Compared to yolks from hens fed the control ration, yolks from hens fed 200, 400, or 800 ppb chromium picolinate contained 14, 29, and 34% less cholesterol, respectively (Table 2) . In contrast, Page (20) did n ot observe any effect of chromium picolin ate supplementation on egg yolk ch olesterol concentration . Likewise, they did not

79

Chromium Picolinate and Egg Cholesterol

TABLE 2. Egg production and egg attributes following supplementation of a layer ration with chromium picolinate. Chromium Variable

o ppb

200 ppb

81.20 ± 3.28 a Egg production, % Egg weight, g 68.54 ± 1.69a 15.31 ± 0.62a Yolk weight, g 2.02 ± O.22a Eggshell breaking strength, kg/cm Eggshell thickness, mm 0.31 ±O.01 a 76.30 ± 1.94b Haugh unit Yolk cholesterol, mg/g 23.11 ± 2.54 a

79.40 60.65 15.24 1.77 0.29 81.70 19.86

400 ppb

± 3.72 a ± 1.47 b ± 0.56a ± 0.18 ab ± 0.01 a ± 2.80 ab ± 2.28 a

81.40 65.98 15.40 1.34 0.27 84.80 16.52

± 4.55 a ± 1.43 a ± 0.86a ± 0.15 b ± 0.01 b ± 2.01 a ± 5.90 ab

800 ppb 79.00 64.54 15.26 1.42 0.29 82.72 15.33

± 3.17a ± 1.86ab ± 0.38 a ± 0.15 b ± 0.01 a ± 2.43 ab ± 1.46 b

a,bMeans (± SEM) within the same row with no common superscript differ significantly (P<0.05).

observe a decrease in serum cholesterol in response to increased dietary supplementation with chromium picolinate. However, in human (1) and animal studies (12, 20) chromium picolinate has consistently decreased serum cholesterol. In the present study, the serum attributes of hens fed a diet containing 800 ppb chromium picolinate differed (P<0.05) from the controls with respect to total cholesterol, HDL-C, LDL-C, Apo-AI, and Apo-B (Table 3). We observed a 39% reduction in serum cholesterol with the 800 ppb

dosage. It is interesting to note that HDL-C increased whereas LDL-C decreased. These trends provide explanations for the differences observed with respect to Apo-AI and Apo-B. McCarty (13) reported that serum total cholesterol and Apo-B decreased and HDL and Apo-AI increased in human subjects fed chromium picolinate. The function of chromium picolinate is not yet clear. It has been postulated that chromium may facilitate the binding of insulin to membrane receptors and thereby

increase the biological activity of insulin (1, 2, 3, 13). Anderson et al. (2) have proposed that chromium acts as a cofactor in initiating insulin action. We did not measure chromium concentration in feed samples or tissue samples. Previous work in our laboratory showed that typical diet contains more than 500 ppb of chromium. Because we cannot distinguish the trivalent chromium from Cr+ 6, it is not clear how much of the measured chromium is attributed to the stainless steel equipment used in diet processing and handling.

TABLE 3. Serum traits of laying hens fed a diet supplemented with chromium picolinate. Chromium Variable

o ppb

200 ppb

400 ppb

800 ppb

114.3 ± 13.4 a 16.9 ± 2.3 b 30.5 ± 3.8 c 11.0 ± 1.5 ab 11.9 ± 2.2b 571.5 ± 54.8 b

75.4±5.1 b 22.5 ± 2.4 a 24.7 ± 3.9 c 17.0 ± 2.5 a 2.9 ± 0.8 b 400.4 ± 43.5 b

(mg/dL) Total cholesterol HDL-CC LDL-Cd APoe A-1 APO B TCf

122.8 13.2 81.2 4.7 51.3 1062.2

± 9.9a ± 1.6b ± 11.6a ± 0.9 b ± 5.2a ± 31.1 a

125.2 ± 17.5 a 17.0 ± 1.8 b 61.3 ± 6.7 b 4.8 ± 0.8 b 14.0 ± 1.8 b 587.8 ± 51.8 b

a,bMeans (± SEM) within the same row with no common superscript differ significantly (P<0.05). cHDL-C = high density lipoprotein-cholesterol. dLDL-C = low density lipoprotein-cholesterol. eAPO = apolipoprotein. fTC = triglycerides.

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Consequently, reported chromium content must be viewed cautiously. The amounts of chromium we added in this study were between 200 and 800 ppb. Thus, our supplemented levels were comparable to that found in unsupplemented rations. However, our supplement was chela ted and therefore likely to have had greater biological availability. In regard to the chelator, picolinic acid is an isomer of nicotinic acid. Grundy et al. (9) reported that the consumption of 1 g nicotinic acid/d by humans decreased serum TG by 52% and total cholesterol by 22% . In view the dose of nicotinic acid used by Grundy et al. (9) and the dose used in the present study, we suspect that the effect we observed was due to chromium rather than picolinic acid. To date there is no NRC requirement (18) for chromium in laying hen rations. Our data demonstrated that supplementing layer diet with an organic form of chromium effectively reduced the cholesterol level in both serum and yolk. It is not clear whether this effect is attributed to the organic form of chromium used in this study. The mode of action of chromium picolinate is worthy of further investigation.

Acknowledgments Published as technical paper No. 11035 of the Oregon Agricultural Experiment Station. The authors thank Nutrition 21 (San Diego, CA) for providing the chromium picolinate used in this study. We thank D. Martin for secretarial assistance.

Lien et al.

and serum traits of pigs. J. Chin. Soc. Anim . Sci. Taiwan. R.O.C. 22:349.

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