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Journal of Animal Science - Animal Nutrition

Effect of selenium supplementation and plane of nutrition on mares and their foals: Foaling data1

 

This article in JAS

  1. Vol. 88 No. 3, p. 982-990
     
    Received: Nov 13, 2008
    Accepted: Nov 02, 2009
    Published: December 4, 2014


    2 Corresponding author(s): carrie.hammer@ndsu.edu
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doi:10.2527/jas.2008-1646
  1. J. F. Thorson*†,
  2. B. J. Karren,
  3. M. L. Bauer*,
  4. C. A. Cavinder,
  5. J. A. Coverdale and
  6. C. J. Hammer 2
  1. Department of Animal Sciences, North Dakota State University, Fargo 58105;
    Center for Nutrition and Pregnancy, North Dakota State University, Fargo 58105; and
    Department of Animal Science, Texas A&M University, College Station 77843

ABSTRACT

To investigate the maternal plane of nutrition and role of Se yeast on foaling variables and passive transfer of IgG, 28 Quarter Horse mares were used in a study with a randomized complete block design. Mares were blocked by expected foaling date and assigned randomly within block to dietary treatments. Dietary treatments were arranged as a 2 × 2 factorial with 2 planes of nutrition, pasture or pasture + grain mix (fed at 0.75% of BW on an as-fed basis) and 2 concentrations of Se yeast (0 or 0.3 mg/kg of DMI). This resulted in 4 treatments: pasture (PA), pasture + Se (PS), pasture + grain mix (PG), and pasture + grain mix + Se (PGS). Assuming DMI at 2% of BW, the mares fed PA and PS received approximately 100% of the calculated NRC (2007) DE requirements, whereas PG and PGS received 120%. Selenium supplementation began 110 d before the estimated foaling date, and all dietary treatments were terminated at parturition. At parturition, foaling variables were recorded. Additionally, placental weight was recorded and 2 samples from each placenta were collected for analysis of DNA, RNA, and protein. Colostrum was obtained for fat, protein, milk urea N, somatic cell count, and IgG analyses. Foal blood samples were collected at 0, 6, 12, 18, and 24 h after parturition for IgG analysis. There was no effect (P ≥ 0.21) of Se or plane of nutrition on foaling variables; however, foal BW as a percentage of mare BW tended (P = 0.10) to be reduced in foals from mares on grain mix (PG and PGS; 7.6%) compared with mares not fed grain mix (PA and PS; 8.0%). There was also no effect (P ≥ 0.20) of Se or plane of nutrition on placental cell number (mg of DNA/g), potential cellular activity (RNA:DNA), expulsion time, or weight. However, mares fed supplemental Se (PS and PGS) had decreased (P = 0.02) placental cell size (24.1 mg of protein/mg of DNA) compared with mares not fed supplemental Se (PA and PG; 32.5 mg of protein/mg of DNA). There was also no effect (P ≥ 0.18) of Se or plane of nutrition on colostral fat, protein, milk urea N, or somatic cell count. However, mares fed grain mix (PG and PGS) had less (P = 0.03) colostral IgG (76.5 g/L) compared with mares not fed grain mix (PA and PS; 126.6 g/L). Foals from mares fed grain (PG and PGS) tended (P = 0.06) to have less overall serum IgG (13.6 g/L) compared with foals from mares not fed grain (PA and PS; 15.3 g/L). These data indicate that the maternal diet during the last one-third of gestation affects placental efficiency and colostral IgG.



INTRODUCTION

Foals are colostrum dependent because of their agammaglobulinemic nature and naive immune systems. Factors that affect passive transfer are colostral quality, ingestion time, and rate of IgG absorption (McGuire et al., 1977; LeBlanc et al., 1992; Tizard, 1996). One or a combination of these factors could lead to failure (<4 g of IgG/L of serum) or partial failure (4 to 8 g of IgG/L of serum) of passive transfer, both of which may adversely affect neonatal health (McGuire et al., 1977).

Neonatal health can also be influenced by maternal nutrition and the availability of nutrients to the fetus. Developmental programming has been used to describe alterations in fetal development caused by an external stimulant (e.g., reduced nutrient supply to the fetus) that have a lasting effect on development (Godfrey and Barker, 2000). Postnatal consequences of developmental programming include reduced neonatal health, skeletal muscle growth, feed efficiency, and athletic performance, all of which affect offspring performance (Ginther and Douglas, 1982; Rossdale and Ousey, 2002; Allen et al., 2004).

In their review, Fang et al. (2002) proposed that oxidative stress caused by overnutrition results in the production of reactive oxygen species, which would be a concern in late pregnancy when metabolic demands are increased. Bernabucci et al. (2005) also reported greater concentrations of reactive oxygen metabolites and lesser concentrations of antioxidants in dairy cattle with greater BCS before calving. Selenium is an antioxidant, and supplementation has been shown to increase serum Se and glutathione peroxidase (Gsh-Px) activity, enhance humoral immune function, decrease Se excretion, and enhance IgG absorption (Knight and Tyznik, 1990; Pagan et al., 1999; Kamada et al., 2007). Despite intense research in the field of developmental programming, little research has focused on the effects of maternal nutrition and Se supplementation in late pregnancy on colostral quality and neonatal performance. It is our general hypothesis that maternal over- or undernutrition will negatively affect colostral quality and that supplemental Se may help offset some of these negative effects. Therefore, the specific objective of this study was to examine the effects of maternal plane of nutrition and Se supplementation on colostral quality and foal development. The current paper focuses on colostral quality and foaling variables, whereas a companion paper (Karren et al., 2009) reports the results of plasma and muscle Se and Gsh-Px concentrations in both mares and foals.


MATERIALS AND METHODS

Care, handling, and sampling of animals were approved by the Texas A&M University Animal Care and Use Committee.

Horses and Treatments

Twenty-eight Quarter Horse mares from the Texas A&M University Horse Center (College Station) were used in a randomized complete block design. Mares were housed at the Texas A&M University Horse Center and maintained according to the farm protocol. Horses ranged from 6 to 19 yr of age and had BW between 465 and 612 kg.

Mares were blocked by expected foaling date and assigned randomly within block to dietary treatments. Dietary treatments were arranged as a 2 × 2 factorial with 2 planes of nutrition (pasture or pasture plus grain mix) and 2 concentrations of selenomethionine (SeMet) supplementation (0 or 0.3 mg of SeMet/kg of DMI). This resulted in 4 treatment groups: pasture (PA; n = 7), pasture + Se (PS; n = 8), pasture + grain mix (PG; n = 5), and pasture + grain mix + Se (PGS; n = 8). Plane of nutrition treatments (PA and PG) were initiated 45 d before the last one-third of pregnancy, whereas SeMet supplementation (PG and PGS) was initiated at the beginning of the last one-third of pregnancy (approximately 110 d before the estimated foaling date). Plane of nutrition treatments were initiated earlier to induce changes in BW and BCS between groups by the beginning of the last one-third of pregnancy. All dietary treatments were terminated at parturition.

All mares had continual access to bermudagrass (Cynodon dactylon) pastures, water, and trace mineralized salt (containing no added Se) throughout the study. Multiple adjacent pastures were used at the facility. Blocks were maintained on the same pasture and were rotated as blocks between pastures as part of farm protocols.

Mares fed grain (PG and PGS) received a supplemental grain mix composed of sorghum, wheat middlings, soybean meal, soybean hulls, and a vitamin and mineral premix (13% CP pellet, Producers Co-op, Bryan, TX) at 0.75% of BW on an as-fed basis. Mares fed supplemental Se (PS and PGS) received supplemental Se yeast in the form of SeMet (Selenosource, Diamond V Mills Inc., Cedar Rapids, IA) at 0.3 mg/kg of DMI. Grain and SeMet treatments (PS, PG, and PGS) were fed in individual 3.0 × 2.9 m stalls twice daily. Selenomethionine was mixed with a small amount of sweet feed (12% CP sweet feed, Producers Co-op) and offered to mares before additional grain to ensure complete ingestion of the SeMet supplement. Mares on the PA treatment were housed in individual stalls during the same time period to equilibrate grazing times for all treatments.

Samples of dietary forage and concentrate were obtained monthly and analyzed as described by Karren et al. (2009). Pasture and grain sample analysis, Se supplement values (Diamond V Mills Inc.), and calculated DE (NRC, 2007) for pasture and grain samples are presented in Table 1. Calculated Se and DE (NRC, 2007) for each of the 4 treatments are presented in Table 2. Although actual pasture intake was not measured, mares fed no supplemental grain (PA and PS) received approximately 100% of calculated NRC (2007) DE requirements for mares in the last one-third of gestation, whereas mares fed PG and PGS received approximately 120% based on an assumed DMI at 2% of mare BW per day (Aiken et al., 1989).

Table 1.

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Table 2.

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Mare Measurements

Mare BW, BCS, and rump fat (RF) measurements were collected every 14 d for the duration of the experiment, and the amount of grain mix offered was adjusted accordingly. Body weight was determined by a digital scale (CAS Corp., Seoul, Korea), and BCS was determined by 4 individuals (2 constant and 2 rotating) on a scale of 1 to 9 as described by Henneke et al. (1983; 1 = poor; 9 = extremely fat). Rump fat was measured via ultrasonic images (SSD-500V, Aloka Inc., Tokyo, Japan) on the left hip at a point 5 cm dorsal of halfway between the first coccygeal vertebra and the ischium (Westervelt et al., 1976).

Foaling Variables

When signs of parturition were present, mares were moved to individual foaling stalls. Bermudagrass hay was offered and the quantity consumed was recorded. All foalings were attended and foaling variables (gestation length and time from water breaking to birth, from birth to placental expulsion, from birth to standing, and from birth to nursing) were recorded. At 12 h after parturition, foal BW, body length, wither height, and hip height were determined.

Placenta Samples and Analysis

After parturition, time of placental expulsion and placental weight were recorded. Two placental samples (approximately 1 g each) were collected from a point 12.7 cm ventral from the umbilical cord in a region lacking major vascularity. This region was chosen in an effort to standardize sampling procedures and minimize sample variation by excluding large blood vessels. These samples were placed in cryogenic vials (5-mL polypropylene low-temperature freezer vials, VWR Int., West Chester, PA), snap-frozen in liquid N, and stored at −60°C until DNA, RNA, and protein analysis.

Freshly thawed placental tissue samples (0.5 g) were homogenized (Polytron with PT-10s probe, Brinkmann, Westbury, NY) in Tris aminomethane, NaCl, and EDTA buffer (TNE buffer; 0.05 M Tris, 2.0 M NaCl, 2 mM EDTA, pH 7.4). Samples were then analyzed for concentrations of DNA and RNA using diphenylamine and orcinol procedures, respectively (Reynolds et al., 1990). Protein in tissue homogenates was determined with Coomassie brilliant blue G (Bradford, 1976), with BSA (Fraction V, Sigma Chemical Co., St. Louis, MO) as the standard (Johnson et al., 1997). Prepared samples were analyzed with a spectrophotometer (Beckman DU 640, Beckman Coulter Inc., Fullerton, CA) and were assessed against concentrations of known standards. Concentration of DNA was used as an index of cell number (hyperplasia), with protein:DNA and RNA:DNA ratios being used as indices of cellular size and potential cellular activity, respectively (Swanson et al., 2000; Scheaffer et al., 2003; Soto-Navarro et al., 2004).

Colostrum Samples and Analysis

After parturition and before nursing, approximately 100 mL of colostrum was collected into a conical vial (VWR Int.) and stored at −20°C until analysis for IgG concentration. A second colostrum sample (approximately 40 mL) was collected and diluted 1:1 with distilled water for fat, protein, milk urea N (MUN), and somatic cell count (SCC) analysis by a commercial laboratory (Texas Dairy Herd Improvement Association, Stephenville, TX). Colostral IgG concentrations were determined by turbidimetric immunoassay by a commercial laboratory (Midland Bioproducts, Boone, IA). Additionally, refractometer (equine colostrum refractometer, Animal Reproduction Systems, Chino, CA) and colostrometer (equine colostrometer, Lane Manufacturing, Denver, CO) readings provided measurements of Brix percentage and specific gravity, respectively, as an indirect quantification of IgG.

Blood Samples and Analysis

Foal blood samples (10 mL) were obtained at birth (0 h; before nursing) and every 6 h thereafter for 24 h for analysis of serum IgG. Samples were collected via jugular venipuncture in sterile blood collection tubes with no additives (Kendall Co., Mansfield, MA). Samples were kept in a refrigerator for approximately 1 h before centrifugation. Samples were centrifuged at 2,700 × g and 10°C for 20 min, and serum was harvested and stored at −20°C until analysis for IgG concentrations by turbidimetric immunoassay (Midland Bioproducts).

Statistical Analysis

Data were analyzed as a randomized complete block design. Foaling variables, foal measurements, and colostral samples were analyzed using the GLM procedure (SAS Inst. Inc., Cary, NC), and repeated measures such as foal serum, mare BW, BCS, and RF were analyzed using the MIXED procedure. Models contained the fixed effects of foaling block (early, mid-1, mid-2, and late), nutrition (pasture vs. pasture + grain mix), Se (none vs. supplement), and the nutrition × Se interaction. Main effects were considered significant when P ≤ 0.05 and were considered a trend toward significance when P ≤ 0.10.


RESULTS

Mare BW, BCS, and RF data are represented in Figures 1, 2, and 3, respectively. There was no effect (P = 0.84) of SeMet on mare BW; therefore, only plane of nutrition effects are presented. Mare BW resulted in a day × nutrition interaction (P = 0.05), with mares fed no grain losing BW from d 0 to 14; however, all mares gained BW over the duration of the experiment (d −45 to 112). Additionally, initial mare BW was not different between treatments at d −45; however, by d 0 and for the remainder of the experiment, mares fed grain had greater (P < 0.05) BW compared with mares fed no grain.

Figure 1.
Figure 1.

Mare BW (least squares means ± SEM) from d −45 to 112 of the last one-third of gestation for mares on pasture and grain treatments. Mare dietary treatments: pasture (PA; n = 7), pasture + Se (PS; n = 8), pasture + grain mix (PG; n = 5), and pasture + grain mix + Se (PGS; n = 8). Selenium did not affect mare BW (P > 0.10); therefore, only plane of nutrition effects are represented. Plane of nutrition × day, P = 0.05. Asterisks (*) denote a difference (P ≤ 0.05) between planes of nutrition.

 
Figure 2.
Figure 2.

Mare BCS (least squares means ± SEM) from d 0 to 112 of the last one-third of gestation for mares on pasture and grain treatments. Mare dietary treatments: pasture (PA; n = 7), pasture + Se (PS; n = 8), pasture + grain mix (PG; n = 5), and pasture + grain mix + Se (PGS; n = 8). Only the main effects of plane of nutrition are presented. Plane of nutrition × day, P < 0.01; plane of nutrition × selenomethionine (Selenosource, Diamond V Mills Inc., Cedar Rapids, IA) supplementation, P = 0.04. Asterisks (*) denote a difference (P ≤ 0.05) between planes of nutrition.

 
Figure 3.
Figure 3.

Mare rump fat (RF; least squares means ± SEM) from d 0 to 112 of the last one-third of gestation for mares on pasture and grain treatments. Mare dietary treatments: pasture (PA; n = 7), pasture + Se (PS; n = 8), pasture + grain mix (PG; n = 5), and pasture + grain mix + Se (PGS; n = 8). Only the main effects of plane of nutrition are presented. Plane of nutrition × day, P < 0.01; plane of nutrition × selenomethionine (Selenosource, Diamond V Mills Inc., Cedar Rapids, IA) supplementation, P = 0.07. Asterisks (*) denote a difference (P ≤ 0.05) between planes of nutrition.

 

Mare BCS was not different at d −45. However, there was a day × nutrition interaction (P < 0.01), with mares fed no grain losing BCS but mares fed grain maintaining BCS over the duration of the experiment (d 0 to 112). There was also an interaction of plane of nutrition with SeMet supplementation (P = 0.04), with PGS mares having the greatest average BCS and PS mares having the least average BCS [BCS = 5.0, 4.6, 5.8, and 6.5 (SEM = 0.2) for PA, PS, PG, and PGS, respectively].

There was a day × nutrition interaction (P < 0.01) for RF, with mares fed no grain losing RF from d –45 until 28 and then staying constant. Additionally, there tended to be an interaction of plane of nutrition with SeMet supplementation (P = 0.07), with PGS mares having the greatest average RF and PS mares having the least [RF = 1.03, 0.80, 1.08, and 1.31 cm (SEM ± 0.12) for PA, PS, PG, and PGS, respectively].

The effects of SeMet and plane of nutrition on foaling variables are represented in Table 3. There was a nutrition × SeMet interaction (P = 0.02) for gestation length, with PGS mares having a shorter gestation length compared with PS and PG mares. Six mares foaled unattended; thus, their foaling time, colostrum, and placental measurements were not included in the statistical analyses, although 12-h foal body measurements and 24-h IgG concentrations in those foals were included. There was no effect of SeMet or plane of nutrition on foal BW, length, wither height, or hip height. Additionally, time from birth to standing and nursing, water-breaking to birth, or birth to placental expulsion did not differ among treatments. The ratio of placenta to mare weight and placenta to foal BW were not affected by treatment; however, the ratio of foal to mare BW tended (P = 0.10) to be greater in mares fed no grain compared with mares fed grain.

Table 3.

Please see the pdf to view this table.

 

The effects of SeMet and plane of nutrition on placental dynamics are presented in Table 4. Placentas from 6 mares that foaled unattended, as well as 1 placenta that was retained and required lavage for removal, were not collected. In addition, 2 samples were eliminated after it was determined the samples were not from the complete placenta. There was no effect (P ≥ 0.20) of plane of nutrition or SeMet on placental weight; placental concentration of DNA, RNA, or protein; total placental DNA, RNA, or protein; RNA:DNA; or protein:DNA. However, mares fed supplemental SeMet (PS and PGS) had decreased (P = 0.02) placental cell size compared with mares not fed supplemental SeMet (PA and PG).

Table 4.

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The effects of SeMet and plane of nutrition on colostral components are depicted in Table 5. There was no effect of SeMet or plane of nutrition on colostral fat, protein, MUN, or SCC. There was also no effect of SeMet on colostral IgG (Table 6). However, mares fed grain had less (P = 0.03) colostral IgG compared with mares fed no grain. Further, mares fed grain had a decreased (P = 0.01) overall colostral sugar percentage (Brix percentage) compared with mares fed no grain. However, specific gravity did not differ across treatments. There was no effect of SeMet on foal serum IgG; however, foals from mares fed grain tended (P = 0.06) to have less overall serum IgG compared with foals from mares fed no grain (Figure 4).

Table 5.

Please see the pdf to view this table.

 
Table 6.

Please see the pdf to view this table.

 
Figure 4.
Figure 4.

Effect of maternal plane of nutrition and selenomethionine (Selenosource, Diamond V Mills Inc., Cedar Rapids, IA) supplementation during the last one-third of equine gestation on foal serum IgG (least squares means ± SEM) concentration for the first 24 h postparturition. Mare dietary treatments: pasture (PA; n = 7), pasture + Se (PS; n = 8), pasture + grain mix (PG; n = 5), and pasture + grain mix + Se (PGS; n = 8). Selenium did not affect foal serum IgG (P > 0.10); therefore, only plane of nutrition effects are represented. Plane of nutrition, P = 0.06. Asterisks (*) denote a difference (P ≤ 0.05) between planes of nutrition.

 

DISCUSSION

Mare body measurements (BW, BCS, and RF) changed as a result of the maternal diet, with mares fed grain (or grain mix; PG and PGS) having greater BW, BCS, and RF at foaling compared with mares fed no grain (PA and PS). Although mares fed no grain were estimated to receive approximately 100% of NRC (2007) recommended allowances for mares in the last one-third of gestation, they did lose BCS and RF. The loss in BCS of mares fed no grain indicates that PA was not sufficient to maintain late-gestation mares in this management setting. Foal BW was not affected by the difference between body measurements of mares fed no grain compared with mares fed grain. However, foal weight expressed as a percentage of mare weight tended to be greater in foals from mares fed no grain than in foals from mares fed grain. This may be a result of foals from mares fed no supplemental grain mobilizing greater body stores (noted by a reduction in mare BCS and RF) from their dams as late gestation progressed, resulting in reduced mare BW at foaling compared with mares fed supplemental grain. It should be noted that foal body composition (fat, muscle, and skeletal components) was not measured, and, although there was no difference in foal weight, differences may exist in body composition.

Foaling variables did not differ among treatments except for gestation length, with mares fed PGS having reduced gestation length compared with mares fed PS and PG. However, after the breeding date and mare history were evaluated, all mares had physiologically normal gestation lengths and treatments did not differ in mare age or parity. Similar reductions in gestation length have been reported with a high maternal plane of nutrition in ewes (Wallace, 2005; Swanson et al., 2008). Wallace (2005) proposed that the reduction in gestation length may be a result of reduced progesterone concentrations as parturition nears, although progesterone concentrations were not measured in this study.

Proper functioning of the placenta is essential for normal fetal growth and development, and foal birth weight is a reflection of placental efficiency (Wilsher and Allen, 2003). Results from the current study indicate that SeMet supplementation reduced placental cellular size (protein:DNA) without a deviation in cell number (mg of DNA/g) or gross placental weight, whereas the maternal plane of nutrition did not affect any placental measurements. Lekatz et al. (2009) reported that cotyledonary protein:DNA tended to be reduced in Se-supplemented ewes when compared with control ewes. In addition, Wallace et al. (2000) reported no difference in placental protein:DNA between control and overfed adolescent ewes. Both these studies concur with the current data for these variables; however, further studies are needed to understand the physiological significance of reduced placental cellular size. The physiological ramifications could be the result of hormone modifications or cellular efficiency. The present study indicates increased placental cellular efficiency because the measured foal growth was not affected by the decreased placental cell size.

There was no effect of plane of nutrition or SeMet on the concentration of colostral fat, protein, or SCC, which agrees with the findings of Swanson et al. (2008). However, Swanson et al. (2008) did report less colostral production, which resulted in overfed ewes having reduced total fat and protein compared with control ewes. A similar trend may have been observed in the current study if the total colostral volume had been quantified. Doreau et al. (1993) also reported no difference in fat or energy content of colostrum from thin vs. obese mares, but in contrast to the current study, they did find greater protein concentrations in colostrum from thin mares. This difference may be related to changes in feed intake because the colostrum samples in the study by Doreau et al. (1993) were obtained on d 2 after foaling, at which point the thin mares were on ad libitum feed. In the study by Doreau et al. (1993), although feed intake was not measured on d 2, thin mares were consuming significantly more feed than obese mares at 1 wk after foaling, which may account for the increased protein content of colostrum reported in that study.

Grain supplementation to mares during the last one-third of gestation resulted in decreased IgG concentration in colostrum and tended to decrease foal serum IgG. This decrease in foal serum IgG was mainly attributed to 12- and 18-h samples, with foals from mares fed grain having lesser IgG concentrations at these 2 time points. In addition, it should be noted that although foals from mares fed grain tended to have lesser overall IgG concentrations, the values from all foals were well above the concentration considered adequate (>8 g of IgG/L of serum) for passive transfer. It cannot be determined if differences in foal serum IgG were the result of differences in colostral consumption or alterations in IgG absorption. Because colostral volume was not measured, total colostral IgG cannot be quantified. It is possible that the decrease in colostral IgG concentration observed in mares fed PG and PGS is simply a reflection of dilution in a larger volume. However, Swanson et al. (2008) reported that overfed ewes had reduced colostral volume and weight compared with control ewes. Kubiak et al. (1989) also reported that obese mares tended to have reduced milk yields compared with control mares. However, based on the BCS classifications used by Kubiak et al. (1989), mares fed grain in the current study were not obese. Instead they more closely resembled the control mares used by Kubiak et al. (1989). Additionally, al-Sabbagh et al. (1995) reported that BCS at lambing did not influence colostral IgG concentration. With these discrepancies, it is evident that further research is needed to determine the relationship between colostral and foal serum IgG and maternal nutrition during pregnancy.

Addition of SeMet to the maternal diet increased Se concentration in colostrum and foal plasma (Karren et al., 2009) but did not influence IgG concentration in colostrum or serum IgG concentration in the foal. Previous studies examining Se supplementation on colostral IgG in cattle and sheep have yielded conflicting results, with reports of both increased IgG (Awadeh et al., 1998) and no change in IgG (Rock et al., 2001; Boland et al., 2005; Swanson et al., 2008) concentrations. In addition, whereas Rock et al. (2001) reported increased serum IgG concentrations in lambs from Se-supplemented ewes, Boland et al. (2005) reported decreased IgG concentrations. Because of differences in timing, sources, and amounts of Se supplementation, direct comparisons among studies are difficult. Additional research investigating the effects of maternal Se supplementation and IgG is clearly needed.

In summary, the maternal diet during late gestation can influence placental development, colostral IgG, and foal serum IgG. However, much work is needed to determine the ramifications of these changes and their mechanisms. Additionally, quantification of total colostral IgG production and foal colostral consumption are vital to determine the mechanism of altered passive transfer of IgG to the neonate.

 

References

Footnotes


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