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ANIMAL NUTRITION |
The Ohio State University and The Ohio Agricultural Research and Development Center, Columbus 43210-1095
Abstract
An experiment evaluated the effects of feeding either a basal non-Se-fortified diet, two Se sources (organic or inorganic) each providing 0.15 and 0.30 ppm Se, or their combination (each providing 0.15 ppm Se) on gilt growth and sow reproductive performance. The experiment was a 2 x 2 + 2 factorial conducted in a randomized complete block design in three replicates. One hundred twenty-six crossbred gilts were started on one of the six treatment diets at 27.6 kg BW. During the grower phase, animals were bled at 30-d intervals with three gilts killed per treatment at 115 kg BW for tissue Se analysis. Fifteen gilts per treatment were bred at 8 mo of age and were continued on their treatment diets for four parities. Sow serum collected within parity was analyzed for Se and glutathione peroxidase (GSH-Px) activity. Tissue Se was determined from five 0-d-old pigs per treatment from fourth-parity sows. Three sows per treatment were killed after the fourth parity for tissue Se analysis. Similar treatment performance responses occurred from 27 to 115 kg BW. Serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased for both Se sources to 0.30 ppm Se during the grower and reproductive periods. Serum Se and GSH-Px activity decreased from 70 to 110 d postcoitum in all treatment groups, but increased at weaning (P < 0.01) in the Se-fortified groups. The number of pigs born (total, live) increased (P < 0.05) with the 0.15 ppm Se level for both Se sources. Tissue and total body Se content of 0-d-old pigs increased with Se level (P < 0.01) and also when the organic Se source (P < 0.01) was fed to the sow. When sows were fed either Se source, pig serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased at weaning. Colostrum and milk Se concentrations increased (P < 0.01) with Se level for both Se sources, but were substantially greater (P < 0.01) when sows were fed organic Se. The combination of Se sources had sow milk and tissue Se values that were similar to those of sows milk and fed 0.15 ppm organic Se. The fourth-parity sows had greater tissue Se concentrations when organic Se level was increased (P < 0.01), more so than when sows were fed inorganic Se. These results suggest that both Se sources resulted in similar sow reproductive performances at 0.15 ppm Se, but sows fed the organic Se source had a greater transfer of Se to the neonate, colostrum, milk, weaned pig, and sow tissues than sows fed inorganic Se.
Key Words: Pigs • Reproduction • Selenium • Sows
Introduction
Sow vitamin E and Se deficiencies have plagued the swine industry for several decades. The NRC (1998)
has therefore increased the recommended dietary vitamin E level to 44 IU/kg for reproduction, while setting the Se recommendation at 0.15 mg/kg diet. Several reports have shown that sodium selenite (dietary or injection) improves sow reproductive performance (Mahan et al, 1974; Young et al., 1977; Chavez, 1985), but vitamin E and Se deficiency is still reported in commercial herds. Previous authors indicated improved responses to supplemental Se more so in multiparous than in first-litter sows, possibly because older animals have more depleted Se reserves. The depletion of Se reserves with advancing parity is exacerbated with greater productivity (Mahan and Newton, 1995). The sow’s dietary Se level can affect the Se status of pigs at birth and weaning, with pigs of a lower Se status experiencing the deficiency onset sooner after weaning than those of a greater Se status (Mahan et al., 1974, 1975).
Feeding organic Se from an enriched Se yeast source to reproducing sows compared with sodium selenite resulted in a greater Se status in both the sow and progeny (Mahan and Kim, 1996). Greater colostrum and milk Se concentrations occur when sows are fed the Se yeast source, thus increasing the Se status of their pigs at weaning (Mahan, 2001). Organic Se provides Se for glutathione peroxidase (GSH-Px) activity, effectively replacing sodium selenite (Mahan and Kim, 1996). Because Se yeast has been approved in the United States as a dietary Se source for swine (FDA, 2002), its value and long-term effects on the sow and progeny were evaluated.
A study was conducted to investigate the effects of inorganic and organic Se sources and levels and their combination in diets provided initially during the grower period and continued through four parities. Reproductive performance and sow and progeny tissue Se concentrations were monitored throughout the study.
Experimental Procedures
Experimental Design and Treatments
The experiment was conducted as a 2 x 2 + 2 factorial arrangement of treatments in a randomized complete block (RCB) design conducted in three replicates. The grower phase of the experiment used a total of 126 gilts allotted to the six treatments in three replicates. Gilts allotted to Treatment 1 were fed basal diets containing no supplemental Se. Gilts allotted to Treatments 2, 3, 4, and 5 were fed diets identical to Treatment 1 with the exception that organic Se (Se yeast) or inorganic Se (selenite) was added at 0.15 and 0.30 ppm Se, respectively. Gilts on Treatment 6 were fed a diet containing both inorganic and organic Se sources, each providing 0.15 ppm Se, for a total of 0.30 ppm Se. The reproductive phase started at the onset of the initial breeding and continued through a four-parity period.
Grower Phase
Crossbred gilts (n = 126) of a Yorkshire x Landrace genetic ancestry were selected at weaning and fed conventional nursery diets until they were transferred to a grower facility in three replicates. Gilts were allotted to grower pens at an average initial BW of 27.6 kg to one of the six treatment pens on the basis of BW in each of the three replicates. Each pen contained seven gilts and provided 1.2 m2 per gilt, with a three-hole, stainless-steel feeder and one nipple waterer. Gilts were provided ad libitum access to their treatment diets and free access to water until a final average replicate weight of 115 kg was achieved. At 30-d intervals, gilts were bled via the vena cava. The blood placed on ice, processed in the laboratory, and the serum collected, stored (–4°C), and later analyzed for its Se concentration and GSH-Px activity. At the end of the grower phase a total of three gilts per treatment group were randomly selected (one per replicate), taken to a local abattoir, and killed. Liver, pancreas, and loin samples were collected, frozen (–4°C), and later analyzed for Se.
On removal from their grower pens, gilts were placed in individual stalls and fed their treatment diet once daily at a quantity to achieve a breeding weight of approximately 135 kg by 8 mo of age (Newton and Mahan, 1993). The quantity of feed provided during this period varied for each animal to achieve the desired breeding weight, but the minimum amount fed was 1.82 kg/d.
Breeding and Postbreeding Period
Gilts were given ad libitum access to their treatment diets for 7 to 10 d before the start of the breeding cycle, whereas sows were given ad libitum access to their gestation treatment diet from weaning until breeding. At approximately 8 mo of age, 15 gilts were selected from each treatment group, artificially inseminated at the onset of estrus, and 12 h later. Semen was obtained from a commercial boar stud (PIC 280 line), stored at 18°C, rotated twice daily, and used within 4 d of collection. From breeding until 14 d postcoitum, parity-one gilts were fed their gestation treatment diet at 1.82 kg/d, whereupon they were fed a larger quantity to 110 d postcoitum. In parity one, the quantity of treatment diet fed from 15 to 110 d postcoitum was 2.0 kg/d, whereas the amount was increased by approximately 0.15 kg for each successive parity.
Sows were bred in their first estrus postweaning. If they did not return to estrus within 20 d postweaning, they were placed into the next breeding group (i.e., 35-d interval) and bred. If an animal failed to cycle in this breeding group, it was removed from the experiment. Animals were weighed and backfat measurements determined at approximately 40 mm off the midline at the last rib at breeding and 110 d postcoitum using a Renco sonoray instrument (Lean Meater, Minneapolis, MN). Blood was withdrawn from the vena cava at 70 and 110 d postcoitum, immediately placed on ice, transported to the laboratory, and the serum was collected and frozen (–4°C) for later determination of Se and GSH-Px activity.
Farrowing and Lactation Period
At approximately 110 d postcoitum, sows were washed and placed in individual farrowing crates, where they were fed their lactation treatment diet at the quantity provided during gestation. At parturition, sows were fed to appetite twice daily until 3 d postpartum, whereupon feed was provided ad libitum until weaning. Within 12 h of farrowing, all pigs were weighed, processed (i.e., ear notched and teeth clipped), and injected with 200 mg of Fe (iron dextran). Body weights were recorded for all stillborn pigs. In addition, tissue samples (i.e., liver, kidney, loin) were collected from stillborn pigs from parity-four sows. If there was not a minimum of five stillborn pigs (total) for each sow treatment group in parity four, a neonatal pig of normal birth weight was randomly selected, weighed and killed. Neonatal and stillborn tissue (liver, loin) had been previously shown to have similar tissue Se concentrations (Mahan and Kim, 1996). The tissues were removed from each 0-d-old pig, and the tissue and entire pig were frozen (–4°C) for later Se analysis. Live 0-d-old pigs were placed on a solid surface and individually scored for the degree of splayed legs. A score of 1 reflected a normal pig with upright leg structure, a score of 2 reflected a weakened structure in the fore or hind legs, and a score of 3 reflected extremely weakened legs with pigs unable to stand.
Within 3 d postpartum, litter size was equalized between sows. It was assumed that milk production was not influenced by inadequate Se, and depletion of sow body Se tissue reserves would be more uniform across treatments if litter size were standardized. Parity-one sows were also expected to have lower milk productions than older sows; therefore, they were weaned at 21 d postpartum, whereas parity-two to -four sows were weaned at 17 d postpartum.
Sow colostrum and milk at weaning was obtained from all functional mammary glands after an i.m. injection (40 U.S.P. units) of oxytocin. Approximately 30 to 40 mL of milk was collected, frozen, and stored at –4°C for the later determination of Se and fat content. At weaning, each sow and three original pigs from each sow were bled. The blood was placed on ice and transported to the laboratory for later processing. Individual sow serum was collected and stored at –4°C for later analysis, whereas serum obtained from the pigs was pooled by litter for subsequent determination of Se and GSH-Px activity. Sows were bled from the vena cava, whereas pigs were bled via cardiac puncture.
Sow BW, backfat thickness, feed intakes, and pig weights were recorded at farrowing and at weaning. Approximately 2 to 4 g of hair was collected along the topline of the shoulder at the time of weaning, and saved for later Se analysis. At the end of parity four, a minimum of three sows completing four parities in succession were taken to a local abattoir and killed. Tissue samples of liver, loin, kidney, and pancreas were collected from each sow, placed on ice, transported to the laboratory, frozen at –4°C, and stored for later Se analysis.
Diet Compositions
From 27 kg BW to breeding, gilts were fed corn-soybean meal (C-SBM) diets formulated to meet or exceed their nutrient needs except for the Se treatment variable. Diets were changed at approximately 65 kg BW. Dietary lysine levels (total) of 1.00 and 0.85% were provided from 27 to 65 and from 65 to 115 kg BW, respectively. The latter diet was also fed during the transition from 115 kg BW to the initial breeding. Sodium selenite and organic Se were each premixed in finely ground corn at 200 mg/kg and added at the appropriate level to the diet mixtures to provide the desired amount of Se. Each premix was analyzed for Se before its incorporation into the diet mixture.
Because of continued muscle development of young reproducing females, gestation diets for parity-one and -two animals were formulated to 0.75% lysine (total), but during parities 3 and 4, the lysine (total) level was 0.55%. Lactation diets were C-SBM with the addition of 5% fat. The dietary lysine (total) level for parity-one lactation was 1.10% and 0.90% for Parity 2 to 4. All diets met or exceeded NRC (1998) nutrient recommendations for vitamins and minerals other than for the treatment Se variable. Diets were sampled at mixing and later analyzed for Se. The compositions of the basal diets during the grower and reproduction phases are presented in Table 1.
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. Serum GSH-Px activities were determined using the coupled method of Lawrence and Burk (1976). The GSH-Px activity was determined on serum with chemical components (glutathione reductase and NADPH) equalized to a standard reaction activity between assays. The analyses of serum from sows and pigs within parity were conducted at the same time. Colostrum and milk fat content was determined by the Babcock method (AOAC, 2000). Hair samples were washed three times in 60°C distilled water, dried, and analyzed for Se. The collected loin and liver of neonatal and stillborn pigs were homogenized, and a sample of each was collected (<3 g) and analyzed for Se. The unused portion of each tissue was incorporated into the entire pig and ground using a Stimpson grinder (model 5412, Louisville, KY) where a homogenous sample was obtained, frozen (–4°C), and later analyzed for total body Se. Statistical analysis of the grower experiment (performance and serum) was conducted as a RCB design in three replicates with the pen serving as the experimental unit. The reproductive sow data were analyzed as a RCB design in a repeated measures analysis of SAS (SAS Inst., Inc., Cary, NC) at three time periods. All reproductive data were analyzed as a one-way ANOVA. Contrasts were used to compare the basal (0 Se) to the other treatments; the combination of Se sources at 0.30 ppm was compared with the two individual Se sources at 0.30 ppm Se. The four treatments that had organic or inorganic Se at the 0.15 and 0.30 ppm Se were analyzed as a 2 x 2 factorial, with the main effects and interactions evaluated. Tissues and serum Se concentration were regressed on dietary organic or inorganic Se levels using the basal diet as the base level (0 Se) of Se. Parity effects were evaluated by linear regression. For reproductive data, sow and litter measurements were the experimental units. Least square treatment means are presented in tables and appropriate interactions by parity are discussed and/or presented in figures.
Results
Because of the greater content of indigenous Se in soybean meal compared with corn, those diets with higher percentages of soybean meal would be expected to have greater Se concentrations. Consequently, the basal diets during the gilt grower period averaged 0.075 and 0.065 ppm Se for the early and late growth stages, respectively. The basal diet used in gestation for parity-one and -two sows contained more soybean meal than those used for parities three and four, the former having a greater Se concentration than the latter diet (i.e., 0.070 and 0.055 ppm Se, respectively). The basal diet fed during lactation in parity 1 contained 0.085 ppm, whereas the basal diet fed during parities two to four contained 0.067 ppm Se.
Grower Stage
Feeding the basal diet or treatment diets with added Se (source and levels) did not influence daily gains, daily feed intakes, and G:F ratios from 27 to 115 kg BW (Table 2).
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). When the basal diet was fed, serum GSH-Px activity was less at each subsequent measurement period compared with the Se fortified diets. A linear (P < 0.01) increase in serum GSH-Px activity occurred as the dietary Se level of both Se sources increased at each 30 d period. However, the rate of increase in GSH-Px activity was less when the dietary Se level increased above 0.15 ppm Se. The effect of Se source or interaction response for GSH-Px activity between the two dietary Se sources and two Se levels was not significant. The liver, loin, kidney, and pancreatic tissue of gilts fed the basal diet had lower (P < 0.01) Se concentrations at the end of the grower period compared with tissues from the Se treatment groups. The liver and loin tissues, but not the kidney, had greater (P < 0.01) Se concentrations when organic Se was compared with the inorganic Se source. Tissue Se concentrations increased linearly (P < 0.01) when Se levels from both Se sources increased, but the rate of increase was greater when organic Se was fed, resulting in a dietary Se level x Se source interaction (P < 0.01). Pigs fed the combination of both Se sources had tissue Se values that were intermediate to the two organic Se treatment sources when fed at 0.30 ppm Se.
Reproductive Performance
Sow BW and their weight changes at the various measurement periods during the four-parity period were not affected by dietary Se source or Se level (Table 3). Sow feed intakes and backfat thickness differed at the various measurement periods, but there was no consistent response to the dietary Se variables.
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). The number of stillbirths was greater (P < 0.05) when the inorganic Se source was fed. Litter birth weights but not individual pig weights were less (P < 0.05) when sows were fed the basal diet as compared with the Se fortified diets. This most likely reflects the smaller litter size of sows fed the basal diet (Table 4). Because pigs were standardized within 3 d postpartum, the number and weights of pigs weaned per litter were understandably similar across treatments. The percentage of neonatal pigs with the severe splay-legged condition was numerically higher when the basal or the inorganic Se diets were fed compared with the organic Se source, but the response was not significant.
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). Sow BW at 110 d postcoitum were greater (P < 0.01) as parity increased, but gestation weight gains and lactation weight changes declined (P < 0.01) as parity advanced. Backfat thickness at the last rib at breeding, 110 d postcoitum, and farrowing decreased quadratically (P < 0.01) by parity, with the greater decrease occurring between parities 1 and 2.
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Total pigs born tended to increase as parity increased (P = 0.06), but there was no effect on the number of live pigs or stillbirths (Table 6). Litter and 0-d-old pig weights increased (P < 0.05) as parity increased. Litter 7-d and weaning weights quadratically increased (P < 0.05) by parity, but litter size had been adjusted and lactation length was longer for parity-one litters. Consequently, after adjusting for length of lactation, both litter and pig daily gains were less (P < 0.01) during parity one, with daily gains of pigs for parities two to four being similar. Parity did not affect the incidence of the splay-legged condition.
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). This resulted in a dietary Se source x Se level interaction (P < 0.01). When the combination of Se sources was fed, serum Se concentrations were generally similar to the 0.30-ppm Se level of the organic Se source. In all treatment groups, there was a decline in serum Se from 70 to 110 d postcoitum, whereupon it increased by weaning except for sows fed the basal diet.
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). Serum GSH-Px activities were generally the same for both Se sources at each measurement period. The 110-d postcoitum period GSH-Px activity plateaued (P < 0.05) at the 0.15-ppm inorganic Se level, but continued to increase when the 0.30-ppm organic Se level was fed. However, the interaction response was not significant. Serum GSH-Px activity also declined from 70 to 110 d in all treatment groups, with an increase occurring by weaning in the Se-fortified groups. Sows fed the basal diet had lower (P < 0.05) GSH-Px activities at weaning than at 110 d postweaning, even though they were consuming more feed and more total Se during lactation.
As the dietary level of both Se sources increased, the Se concentration in colostrum and milk increased linearly (P < 0.01) above that of the basal, but the increase was at a lesser rate (P < 0.05) when the inorganic Se level increased. However, it was greater when the organic Se level increased (Table 7). This resulted in a dietary Se source x Se level interaction (P < 0.05) response for the Se content in the milk but not colostrum. Sows fed the combination of Se sources had colostrum and milk Se concentrations similar to those of sows fed the 0.15-ppm organic Se source. The fat content of colostrum and milk was not affected by dietary treatments.
Loin and liver Se concentrations of 0-d-old pigs increased linearly (P < 0.01) as the organic Se level fed to the sow increased, whereas only the 0-d-old pig liver Se concentration increased (P < 0.01) when the inorganic Se level increased in the sow diet (Table 8). Total body Se (mg/pig) content of 0-d-old pigs increased (P < 0.01) when either Se source was fed to gestating sows. As dietary Se levels increased, the concentration and the rate of total pig Se increased more at each Se level when the organic Se source had been fed to the sow. This resulted in a Se source x Se level interaction (P < 0.05). Total body Se (mg/pig) of 0-d-old pigs was approximately doubled (P < 0.01) when organic Se was fed to the sows at 0.30 ppm Se compared with the total body Se content of pigs from sows fed inorganic Se at 0.30 ppm Se.
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). Weanling pig serum Se was also greater (P < 0.01) when sows were fed organic Se vs. inorganic Se. Pig serum Se increased quadratically (P < 0.05), plateaued at 0.15 ppm Se when inorganic Se was fed to sows, but increased linearly (P < 0.01) when the organic Se level increased. This resulted in a dietary Se level x Se source interaction (P < 0.01). Pig serum GSH-Px activity was less (P < 0.01) when sows were fed the basal diet than when fed the Se-fortified diets (Table 7). Pig serum GSH-Px activity increased (P < 0.05) as sow dietary Se level increased to 0.30 ppm Se from both Se sources. These serum GSH-Px activities did not differ between the two Se sources nor was the interaction significant.
A linear increase (P < 0.01) in sow liver, loin, and pancreas Se concentrations occurred from both Se sources as dietary Se level increased, values that were above that of sows fed the basal diet (Table 8). However, sows that were fed organic Se had greater (P < 0.05) Se concentrations in the liver, loin, and pancreas compared with sows fed the inorganic Se source. Kidney Se concentration, however, was greater (P < 0.01) when inorganic Se had been fed to the sows. Tissue Se concentrations of sows fed the combination of Se sources were similar to those of sows fed 0.15 ppm organic Se, except for the kidney, which was similar to those of sows fed 0.30 ppm inorganic Se.
Hair Se contents were greater when sows were fed increasing levels of organic (P < 0.01) or inorganic Se (P < 0.05), but the Se concentration was substantially greater (P < 0.05) when the organic Se source was fed (Table 7). This resulted in a Se source x Se level interaction (P < 0.01) response. When the combination of Se sources was fed, sow hair Se concentrations were generally similar to the group fed 0.15 ppm organic Se.
Treatment Se Responses by Parity
Sow serum Se increased in a quadratic (P < 0.05) manner at 70 d postcoitum as parities increased with the greater increase to parity two, but no differences occurred at 110 d postcoitum or at weaning (Table 9). Serum Se, however, declined from 70 to 110 d postcoitum, whereupon it increased to weaning resulting in a Se treatment by parity interaction (P < 0.01).
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). Sow GSH-Px activity declined in all treatment groups by parity at both 110 d postcoitum (Figure 1) and at weaning (Figure 2).
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). Although the three-way interaction of Se sources x Se level was not significant, there was a trend for an increase in sow hair Se concentration by parity when sows were fed the two inorganic Se levels or when 0.15 ppm organic Se was fed, but not when the 0.30-ppm organic Se source was fed (Figure 3).
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). A Se source x Se level x parity three-way interaction (P < 0.01) resulted for milk Se concentration (Figure 4). Sows fed the basal diet and those fed 0.15 and 0.30 ppm inorganic Se had declining milk Se concentration by parity, whereas when sows were fed organic Se, the milk Se concentrations were greater and relatively constant by parity within each organic Se level.
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). Serum Se concentrations of pigs generally declined as each parity progressed, particularly when pigs nursed sows fed the basal diet, but were relatively constant within each of the Se-fortified treatment groups between parities two to four (Figure 5). Pig serum GSH-Px activities declined in all treatment groups as parity increased (P < 0.01; Table 9). Although the decline occurred in all treatment groups, it was greater when sows were fed the basal diet (Figure 6).
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None of the treatment diets demonstrated any difference in performance responses during the grower period. The lack of response to Se supplementation is consistent with other reports (Mahan et al., 1999). However, gilts fed the basal diet had lower tissue Se concentrations at 115 kg BW than those fed inorganic Se, which was lower than those fed organic Se. The higher Se status of gilts is of particular importance in the liver (P < 0.01), where the most labile form of Se is thought to reside.
The subsequent reproductive data indicated that an inorganic or organic Se source, when fed at 0.15 ppm, results in improved reproductive performance with no further improvement when the 0.30-ppm Se level is fed. There were, however, a greater number of stillbirths (P < 0.05) when the inorganic Se source was fed. The smaller litter size from sows fed the basal diet occurred at each parity and was not attributable to declining performances of older sows (data not included). Although this response differs somewhat from that reported in the literature (Mahan et al., 1974; Chavez, 1985), the females in our study may have reflected different Se statuses at the time of the breeding cycle, whereas other reports do not indicate different Se statuses before starting their reproductive studies.
Serum Se concentrations of gilts and sows increased to the 0.30-ppm Se level for both Se sources during both the grower and reproductive periods (Tables 2 and 7). However, GSH-Px activities seemed to plateau at the 0.15-ppm Se level, with only a small increase to the 0.30-ppm Se level. These responses are generally consistent with our previous reports (Mahan and Parrett, 1996; Mahan et al., 1999). The treatment containing the combination of Se sources (0.30 ppm Se) had serum Se and GSH-Px measurement values consistent with the dietary 0.30-ppm Se groups. These results suggest that either Se source was adequate at the 0.15 ppm Se level to meet the sow’s Se need for reproduction and for the synthesis of the GSH-Px enzyme. However, as the dietary Se level increased to 0.30 ppm Se, there was a further increase in sow blood and tissue Se concentrations, resulting in greater Se concentrations in the fetus, colostrum and milk, particularly when the organic Se source was fed.
The decline in serum Se concentration and the concurrent decline of serum GSH-Px activity from 70 to 110 d postcoitum in the sows from all treatment groups suggests that Se was transferred to conceptus products during late gestation, where less of the element was perhaps available for GSH-Px production and/or activity in the pregnant sow. The transfer of Se in utero to the developing fetus and the subsequent greater body stores of Se have been shown to be influenced by dietary Se source and level fed to the sow (Mahan et al., 1977; Piatkowski et al., 1979; Mahan and Kim, 1996). This suggests that the transfer of Se into these conceptus products may have caused the decline in sow serum Se concentration and sow GSH-Px activity during late gestation.
Liver Se concentration and total body Se content in the neonate increased when either inorganic or organic Se sources were fed to the sow. The total body Se content in the neonate was approximately doubled when organic Se was provided, suggesting a greater store of labile Se reserves in pigs from sows fed organic Se. The importance of both vitamin E and Se in the neonatal pig’s status of these nutrients is supported by the results of Lannek et al. (1962), Tollerz and Lannek (1964), and Loudenslager et al. (1986).
Organic Se from the yeast source resulted in greater Se concentration in the colostrum and milk of sows when compared with the inorganic Se source. This response is attributed to the selenomethionine contribution from the organic Se yeast source (Kelly and Power, 1995). On absorption, selenomethionine would be expected to become incorporated into milk protein (via RNA protein synthesis) essentially replacing methionine in milk protein in proportion to the selenomethionine:methionine ratio in the circulatory system. The incorporation of inorganic Se into colostrum and milk was less than from the organic Se source, but the combination of Se sources (each providing 0.15 ppm Se) resulted in Se concentrations similar to the sows fed 0.15 ppm organic Se. This response is similar to that reported by Mahan (2000).
As parities progressed, sow milk Se concentration decreased when sows were fed the basal diet or when either inorganic Se level was fed. This decline is consistent with other reports (Mahan et al., 1991, 1994) and suggests that 1) labile sow Se tissue reserves were becoming depleted with advancing parity; 2) tissue reserves were not readily mobilized; or 3) mammary tissue of older females could not incorporate or transfer dietary inorganic Se or tissue Se reserves into milk as effectively as younger sows. In contrast, the Se content of colostrum and milk of sows fed the organic Se source increased when dietary Se levels increased from 0.15 to 0.30 ppm, and its concentration in milk remained relatively constant between parities. The importance of greater milk Se concentrations has been shown to increase the Se status in the nursing pig at weaning (Mahan and Kim, 1996), and this higher status may help reduce the postweaning mortality frequently encountered (Mahan et al., 1974, 1975). It is thus probable that the dietary source or level of Se may be more critical in maintaining the metabolic needs of the mature sow, or its transfer to their conceptus and milk products, and that sow tissue reserves are less readily mobilized in older sows, whereas in younger animals tissue Se reserves may be more labile.
Although the milk Se concentrations of sows fed inorganic Se was less when organic Se was provided, there apparently was enough Se in sow milk from either source to result in similar GSH-Px activities of their progeny. This suggests that the amount of Se provided from milk for piglet GSH-Px synthesis is relatively low and could be achieved when sows are fed either Se source at 0.15 ppm Se. The GSH-Px activity in the serum of young pigs has been shown to increase as the pig matures (Mahan et al., 1999). The young nursing pig, however, seems to be largely dependant on it own synthesis of GSH-Px, because the sow milk analyzed in this study showed little or no GSH-Px activity (Mahan, unpublished data).
There was a decline in sow serum GSH-Px activity (P < 0.01) from all treatment groups as parity progressed, implying a decreased production of GSH-Px in females with age. Although we attempted to standardize enzyme activity in this experiment, the effect of sow age on GSH-Px activity needs further examination.
Sow tissue Se concentrations at the end of the four-parity period demonstrated that sows fed organic Se had greater Se stores than when inorganic Se had been fed; responses similar to other reports (Mahan and Kim, 1996). However, Se concentrations from each treatment group, including the basal treatment, had greater liver Se concentrations after parity four compared with values at the beginning of the reproductive study. Consequently, it would seem that the dietary Se source and level fed to the sow during gestation and lactation would be the primary source having a greater influence on the Se status of the nursing pig, whereas sow tissue reserves appear to have a less important role.
Hair Se increased in response to both dietary Se source and level, and to a small degree as parity increased, but the greater response seemed to originate from the dietary Se source. The hair Se concentration when sow were fed 0.30 ppm Se from the organic Se yeast seemed to be relatively constant over the four parity period, whereas the other treatment groups showed a small but nonsignificant increase by parity. The S in cysteine concentration in swine hair is thought to be greater (i.e., >13%) than other tissues (Mahan and Shields, 1998). Because of the substitution of S with Se in these AA, the resulting hair has a greater relative Se concentration when selenomethionine is in the diet. Because either of these AA can be substituted for the other by the pig, it suggests that selenomethionine would be a major contributor to hair Se when present in the animal’s circulatory system. The capability of swine to incorporate Se into hair was therefore more fully met when the organic Se source was fed at the 0.30-ppm Se level, whereas it was not when inorganic Se was a major Se source or when the 0.15-ppm organic Se source was fed. The present experiment suggests that the Se content of sow hair appears to largely reflect the dietary source and level of organic Se fed to the sow, and does not reflect the sows Se status.
Implications
Inorganic or organic Se, fed at 0.15 ppm from the grower period through the reproductive cycle, resulted in similar sow reproductive performance as measured by litter size. Stillbirths were, however, lower when the organic Se source was fed. As dietary organic Se levels increased to 0.30 ppm Se, more Se was retained by the sow or transferred to the various conceptus tissues. The feeding of organic Se increased Se concentrations in the neonate, colostrum, milk, and sow tissues compared with inorganic Se. Sows fed an equal combination of Se from either organic or inorganic source (total 0.30 ppm Se) generally responded similarly as those fed 0.15 ppm Se from the organic Se source.
Footnotes
1 Salaries and research support were provided by state and federal funds appropriated to The Ohio Agric. Res. and Dev. Center and The Ohio State Univ. 
2 Partial support for this project and the organic Se product (Sel-Plex) was provided by Alltech Biotechnology Center, Nicholasville, KY.
3 Appreciation is expressed to K. Mays and L. Warnock for animal care and data collection, to F. Cihla and M. Watts for laboratory assistance, and to B. Bishop for statistical analyses.
4 The experimental use of animals and procedures followed was approved by the University Animal Care Committee.
5 Correspondence: 2027 Coffey Rd. (phone: 614-292-6987; fax: 614-292-7116; e-mail: mahan.3{at}osu.edu).
Received for publication March 13, 2003. Accepted for publication February 18, 2004.
Literature Cited
AOAC. 2000. Official Methods of Analysis. 17th ed. Assoc. Offic. Anal. Chem., Arlington, VA.
Chavez, E. R. 1985. Nutritional significance of selenium supplementation in a semi-purified diet fed during gestation and lactation to first-litter gilts and their piglets. Can J. Anim. Sci. 65:497–506.
Chavez, E. R., and K. L. Patton. 1986. Response to injectable selenium and vitamin E on reproductive performance of sows receiving a standard commercial diet. Can. J. Anim. Sci. 66:1065–1074.
FDA. 2002. Food additives permitted in feed and drinking water of animals; selenium yeast. Fed. Register 67 (No. 137/July 17):46850.
Kelly, M. P., and R. F. Power. 1995. Fractionation and identification of the major selenium containing compounds in selenized yeast. J. Dairy Sci. 78(Suppl. 1):237. (Abstr.)
Lannek, N., P. Lindberg, and G. Tollerz. 1962. Lowered resistance to iron in vitamin E-deficient piglets and mice. Nature (London) 195:1006–1007.
Lawrence, R. A., and R. F. Burk. 1976. Glutathione peroxidase activity in selenium deficient rat liver. Biochem. Biophys. Res. Commun. 71:952–958.[Medline]
Loudenslager, M. J., P. K. Ku, P. A. Whetter, D. E. Ullrey, C. K. Whitehair, H. D. Stowe, and E.R. Miller. 1986. Importance of diet of dam and colostrum to the biological antioxidant status and parenteral iron tolerance of the pig. J. Anim. Sci. 63:1905–1914.
Mahan, D. C. 1991. Assessment of the influence of dietary vitamin E on sows and offspring in three parities: Reproductive performance, tissue tocopherol, and effects on progeny. J. Anim. Sci. 69:2904–2917.[Abstract]
Mahan, D. C. 1994. Effects of dietary vitamin E on sow reproductive performance over a five parity period. J. Anim. Sci. 72:2870–2879.[Abstract]
Mahan, D. C. 2000. Effect of organic and inorganic selenium sources and levels on sow colostrum and milk selenium content. J. Anim. Sci. 78:100–105.
Mahan, D. C., and Y. Y. Kim. 1996. Effect of inorganic or organic selenium at two dietary levels on reproductive performance and tissue selenium concentrations in first parity gilts and their progeny. J. Anim. Sci. 74:2711–2718.[Abstract]
Mahan, D. C., and E. A. Newton. 1995. Effect of initial breeding weight on macro- and micro-mineral composition over a three parity period using a high-producing sow genotype. J. Anim. Sci. 73:151–158.[Abstract]
Mahan, D. C., and N. A. Parrett. 1996. Evaluating the efficacy of selenium-enriched yeast and sodium selenite on tissue selenium retention and serum glutathione peroxidase activity in grower and finisher swine. J. Anim. Sci. 74:2967–2974.[Abstract]
Mahan, D. C., and R. G. Shields, Jr. 1998. Essential and nonessential amino acid composition of pigs from birth to 145 kilograms of body weight, and comparison to other studies. J. Anim. Sci. 76:513–521.
Mahan, D. C., T. R. Cline, and B. Richert. 1999. Effects of dietary levels of selenium-enriched yeast and sodium selenite as selenium sources fed to grower-finisher pigs on resulting performance, tissue selenium, serum glutathione peroxidase activity, carcass characteristics, and loin quality. J. Anim. Sci. 77:2172–2179.
Mahan, D. C., A. L. Moxon, and J. H. Cline. 1975. Efficacy of supplemental selenium in reproductive diets on sow and progeny serum and tissue selenium values. J. Anim. Sci. 40:624–631.
Mahan, D. C., A. L. Moxon, and Mariana Hubbard. 1977. Efficacy of inorganic selenium supplementation to sow diets on resulting carry-over to their progeny. J. Anim. Sci. 45:738–746.
Mahan, D. C., L. H. Penhale, J. H. Cline, A. L. Moxon, A. W. Fetter, and J. T. Yarrington. 1974. Efficacy of supplemental selenium in reproductive diets on sow and progeny performance. J. Anim. Sci. 39:536–543.
Newton, E. A., and D. C. Mahan. 1993. Effect of initial breeding weight and management system using a high-producing sow genotype on resulting reproductive performance over three parities. J. Anim. Sci. 71:1177–1186.[Abstract]
NRC. 1998. Nutrient Requirements of Swine. 10th ed. Natl. Acad. Press, Washington, DC.
Piatkowski, T. L, D. C. Mahan, A. H. Cantor, A. L. Moxon, J. H. Cline, and A. P. Grifo, Jr. 1979. Selenium and vitamin E in semi-purified diets for gravid and nongravid gilts. J. Anim. Sci. 48:1357–1365.
Tollerz, G., and N. Lannek. 1964. Protection against iron toxicity in vitamin E deficient piglets and mice by vitamin E and synthetic antioxidants. Nature 201:846–847.[Medline]
Young, L. G., R. B. Miller, D. M. Edmeades, A. Lun, G. C. Smith, and G. J. King. 1977. Selenium and vitamin E supplementation of high moisture corn diets for swine reproduction. J. Anim. Sci. 45:1051–1060.
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