sodium selenite to supply total selenium levels comparable to a naturally high selenium diet. Sodium selenite additions to the naturally high selenium diets did ...
SELENIUM
SUPPLEMENTATION OF NATURALLY HIGH SELENIUM DIETS FOR SWINE 1
P. K. Ku, 2 E. R. Miller, 2 R. C. Wahlstrom, a A. W . Groce7 J. P. Hitchcock 2 and D. E. Ullrey 2
Michigan State University, East Lansing 48823 and South Dakota State University, Brookings 57006 Summary trials were conducted (one at MichiT WO gan State University and a second at South
Dakota State University) involving supplementation of naturally high selenium swine diets (0.24 to 0.45 ppm) with 0.1 ppm of selenium from sodium selenite. In one trial, a low selenium diet (0.04 ppm) was supplemented with 0.40 ppm of selenium from sodium selenite to supply total selenium levels comparable to a naturally high selenium diet. Sodium selenite additions to the naturally high selenium diets did not significantly increase longissimus muscle or kidney selenium concentrations and increased liver selenium concentrations only slightly. Tissue selenium levels resulting from adding 0.40 ppm of selenium from sodium selenite to a naturally low selenium diet (0.04 ppm) were significantly lower than when a naturally high selenium diet (0.44 ppm) was fed. It appears that the dietary level of naturally-occurring organic selenium compounds is much more significant in influencing the tissue selenium concentration of the pig than supplemental selenium from sodium selenite. Introduction A previous study (Ku et al., 1972) demonstrafed a significant linear correlation between natural dietary selenium concentration and longisslmus selenium Concentration of swine. Ewan, Baumann and Pope (1968) demonstrated a similar phenomenon in lambs. However, there is evidence (Groce et al., 1971) that increasing increments of inorganic selenium added to a low selenium diet do not result in increased tissue selenium concentrax Published with approval of the Michigan Agricultural Experiment Station Director as ]'ournal Article No. 6156. 2 Department of Animal Husbandry, Michigan State University. s Department of Animal Science, South I?akota State University. 501
tions once the need for selenium has been fulfilled. The study to be reported here was concerned with the effects of inorganic selenium supplementation of naturally high selenium diets upon tissue selenium concentration. Experimental Procedure Two trials involving 28 pigs were conducted, one at Michigan State University (MSU) and a second at South Dakota State University (SDS). The diets used in both trials (table 1) contained corn and soybean meal supplemented with minerals and vitamins. A 16% crude protein diet was fed from weaning to approximately 50 kg body weight, and a 13% crude protein diet was fed to slaughter. Both feed and water were offered ad libitum. The SDS basal diets were compounded at Brookings, South Dakota from locally purchased ingredients. The SDS diets fed at MSU were mixed before those fed at SDS, but all diet ingredients were taken from a common bulk bin supply. Periodic additions of soybean meal to this bulk bin were made prior to mixing of the experimental diets, and these additions were obviously not homogeneous with respect to selenium concentration since the SDS basal diets fed at MSU contained 0.448 and 0.438 ppm selenium (16% and 13% crude protein diets, respectively) while those fed at SDS contained 0.296 and 0.238 ppm. The MSU basal diet was compounded at East Lansing, Michigan from locally purchased ingredients. A single sodium selenite premix was prepared at MSU and divided for use at the two locations. Anhydrous sodium selenite 4 was ground with a small amount of corn meal i n a mortar, and this premix was further diluted and mixed with finely ground corn in a laboratory blendor. The final concentration of selenium in the premix was 20 ppm. ~Aifa Inorganies, Inc., Beverly, Massachusetts. JOURNAL OF ANIMAL SCIENCE, vol. 37, no. 2, 1973
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KU ET AL. TABLE 1. C O M P O S I T I O N OF BASAL D I E T S MSU trial
Ingredient Corn Soybean meal (49% CP) Soybean meal (44% CP) Dicalcium phosphate Limestone Salt Trace mineral salt (high Zn) a Vitamin-trace mineral premix b Vitamin-antibiotic premix c
MSU basal 78.0 19.0
8S.5 11.5
"if0 1.0 0.5
"i:0 1.0 0.5
"015 ........
"0~
100.0 Crude protein, % d Selenium, ppm ~ a-tocopherol, I U / k g "
SDS trial
16 0.042 7.9
100.0 13 0.041 7.9
SDS basal
SDS basal
76.0 85.0 76.0 . . . . . . . . . . . . 21.2 12.6 21.2 1.3 I. 3 1.3 0.5 0.5 0.5
85.0 i2~6 1.3 0.5
"015
"015
"0~5
"0:~
. . . .
o , , .
, , . ,
. , o .
0.1
0.1
0.1
0.1
100.0
100.0
100.0
100.0
16 0.448 7.9
13 0.438 7.9
16 0.296 7.1
13 0.238 7.1
a Provided the following per kilogram of diet:zinc, 40 rag; cobalt, 1.1 rag; iron, 10 mg; copper, 2.4 mg; manganese, 20 rag; iodine, 0.55 milligrams. b Provided the following per kilogram of diet:vltamln A, 3,300 IU; vitamin D2, 660 IU; riboflavin, 3.3 rag; nicotinic acid, 17.6 rag; d-pantothenic acid, 13.2 mg; choline chloride, 110 rag; vitamin B~, 19.8 #g; zinc, 74.8 mg; manganese, 37.4 mg; iodine 2.7 mg; copper, 9.9 mg; iron, 59.4 milligrams. e Provided the following per kilogram of diet:vitamin A, 3,300 IU; vitamin D, 440 IU; riboflavin, 3.3 mg; d-pantothenic acid, 6.6 mg; nicotine acid, 14.8 rag; choline chloride, 16.5 mg; vitamin B~, 16.5 /zg; chlortetracycline, 22 mg (16% CP diet) or 11 mg (13% CP diet). d Calculated. e Analyzed. The a-tocopheroI analyses were performed by W. T. Ely.
At MSU, 16 Yorkshire x Hampshire pigs weighing an average of 7.9 kg were randomly assigned to one of four diets and housed in a completely enclosed building with a solid concrete floor. Pigs on treatment 1 were fed the MSU basal diet (0.04 ppm selenium) supple mented with 0.40 ppm selenium from sodium selenite. Treatment 2 received the SDS basal diet (0.44 ppm selenium) from weaning to slaughter. Treatment 3 received the SDS basal diet supplemented with 0.1 ppm selenium from sodium selenite to 55 days before slaughter, and treatment 4 was the same as treatment 3 except supplemental selenium was fed to slaughter. At SDS, 12 Chester White x YorkshireHampshire pigs weighing an average of 11.5 kg were randomly assigned to SDS treatments I, 2 and 3 corresponding to MSU treatments 2, 3 and 4, respectively. 'Pigs on SDS treatment 2 had selenium withdrawn from the diet 58 days before slaughter. SDS pigs were housed in concrete-floored pens with access to an outside concrete feeding floor. The pigs were weighed and feed consumption was determined at biweekly intervals. All pigs were slaughtered at the conclusion of the feeding trials. Samples of liver, kidney and longisslmus muscle were stored at --20 C until analyzed. All tissues (3 to 5 g) were homogenized in a Polytron 5 homogenizer with s Willems Polytron R, Brinkman Instruments, Westbury,
N e w York.
an appropriate volume of deionized, distilled water to facilitate uniform sampling. Feed samples were ground three times through a 10 mesh screen in a Wiley mill and stored at --20C until analyzed for selenium and atocopherol concentration. Selenium concentraions of tissues and feed were determined fluorometrically by the method of Hoffman, Westerby and Hidiroglou (1968) as modified by Groce et al. (1971). Alpha-tocopherol in the feed was isolated by thin layer chromatography and quantitated colorimetrically according to the method of Ames (1971). The data from each trial were evaluated separately by analysis of variance (Snedecor, 1956), and the treatment means were compared by application of the multiple range test of Duncan (1955). Results and Discussion The performance data of the pigs from these two trials are summarized in table 2. Supplementation of the SDS basal diets with selenium from sodium selenite had no significant effect on growth rate or feed consumption. The slightly lower average daily gain of pigs on treatment 4 in the MSU trial was due to the poor performance of one pig which showed evidence of pneumonia at slaughter. Muscle, liver and kidney selenium levels are presented in table 3. Supplementation of the
HIGH SELENIUM DIETS FOR SWINE
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T A B L E 2. E F F E C T OF N A T U R A L D I E T A R Y S E L E N I U M L E V E L S A N D S O D I U M S E L E N I T E SUPPLEMENTATION UPON PIG PERFORMANCE M S U trial
Item
M S U basal -t-0.4 p p m Se 1 4 7.9 97.3 0.64 1.77 0.36
Treatment No. of pigs Initial wt, kg Final wt, kg Daily gain, kg Daily feed, kg Gain/feed
SDS trial
SDS basal
SDS basal -q-0.1 p p m Se ( W D ) a
SDS basal --t-0.1 p p m SE ( N W D ) ~
SDS basal
SDS basal -1-0.1 p p m Se ( W D ) b
2 4 8.1 99.8 0.65 1.87 0.35
3 4 7.8 100.9 0.67 1.82 0.37
4 4 7.9 93.7 0.61 1.65 0.37
1 4 11.6 104.9 0.80 2.41 0.33
2 4 11.4 103.9 0.79 2.55 0.31
SDS basal q-0.1 p p m Se ( N W D ) i, 3 4 11.4 111.6 0.85 2.45 0.35
9 Selenium supplement withdrawn (WD) 55 days before slaughter in treatment 3, not withdrawn (NWD) in treatment 4. b Selenium supplement withdrawn (WD) 58 days before slaughter in treatment 2, not withdrawn (NWD) in treatment 3.
SDS basal diets with 0.1 ppm of selenium from sodium selenite did not significantly increase muscle selenium concentration in either the MSU or SDS trial. Adding 0.4 ppm of selenium from sodium selenite to the MSU basal diet to bring the total selenium concentration to that of the SDS basal diet resulted in a significantly (P
