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Journal of Animal Science - Animal Nutrition

Effect of dietary calcium and phosphorus levels on the total tract digestibility of innate and supplemental organic and inorganic microminerals in a corn-soybean meal based diet of grower pigs12

 

This article in JAS

  1. Vol. 91 No. 6, p. 2775-2783
     
    Received: June 6, 2012
    Accepted: Mar 4, 2013
    Published: November 25, 2014


    4 Corresponding author(s): mahan.3@osu.edu
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doi:10.2527/jas.2012-5532
  1. J. S. Jolliff33 and
  2. D. C. Mahan 4
  1. The Ohio State University and The Ohio Agricultural Research and Development Center, Columbus 43210-1095

Abstract

The effects of Ca and P (CaP) levels and micromineral sources on mineral digestibility were evaluated in growing pigs. Treatments consisted of 2 levels of CaP and 3 trace mineral (TM) treatments arranged as a 2 × 3 factorial in a randomized complete block design with 8 replicates. The CaP levels evaluated were: 1) 0.65% Ca and 0.55% P [standard CaP (Std CaP)], and 2) 1.00% Ca and 0.85% P (High CaP). The TM treatments were: 1) Basal, without supplemental TM, 2) Basal supplemented with organic TM, and 3) Basal supplemented with inorganic TM. Both organic and inorganic TM premixes added 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn/kg diet. Diets were formulated using corn soybean meal with a Ca to P ratio of 1.18 in both CaP treatments. Barrows with an initial BW of 45 kg were acclimated to stainless steel metabolism crates where diets were fed for 14 d before a 10-d collection period. Pigs within replicates were fed equivalent amounts of feed at 0800 and 1600 h each day with water provided free choice. Total feces, urine, and feed orts were collected daily. Essential macro- and microminerals were analyzed by inductively coupled plasma analysis. Increasing dietary CaP decreased the digestibility of Ca and Zn. Phosphorus digestibility did not change when the P inclusion level increased from 0.55 to 0.85% Ptotal. The High CaP level resulted in a lower urinary excretion of most minerals, particularly Cu (P < 0.05) and Mn (P < 0.05), as dietary CaP level increased but the others were not statistically significant. A summary of the ATTD for each of the experimental variables was statistically analyzed and averaged for the experiment. Although there were few statistical differences with individual minerals, they generally demonstrated a decline in digestibility when the High CaP was fed, averaging a 3% lower digestibility consistently than when the Std CaP level was fed. Organic TM averaged an approximately 5% greater digestibility than the average inorganic microminerals with the difference between minerals within each source relatively consistent. These results indicate that CaP level had the greatest effect on mineral digestibility, organic microminerals had a greater digestibility than inorganic minerals, and the innate microminerals had an average apparent digestibility of 45%.



INTRODUCTION

The availability of the essential dietary microminerals for swine are influenced by several factors, with the major ones being feed ingredients in the diets, dietary levels of Ca and P, and exogenous enzymes. Because of variable concentrations and unknown availabilities, the innate dietary microminerals are commonly disregarded in feed formulation (Reese and Hill, 2010). Consequently, if the innate microminerals are partially available to the animal and the innate minerals are at or above NRC (1998) requirements, then the final diet may include excesses of at least some of the essential microminerals.

Work in the 1950s and 1960s described a relationship between Ca and Zn where diets high in Ca caused parakeratosis (Lueke et al., 1956; Newland et al., 1958; Hoefer et al., 1960). Furthermore, increased dietary Ca and P levels may have a negative effect on micromineral use in tissue. The mechanism by which Ca reduces the availability of microminerals may also involve its relationship with phytate (Ellis et al., 1982; Mills, 1985; Jolliff and Mahan, 2012). Reducing the efficiency of mineral absorption by increasing dietary Ca can increase the proportion of microminerals excreted and, thus, increase their dietary requirement. When they are subsequently applied to soil in excessive amounts, both Cu and Zn can reduce soil biomass and soil respiration rates of bacteria, including the N-fixing species and fungi (Christie and Beattie, 1989; McGrath et al., 1995, Valsecchi et al., 1995, Rajapaksha et al., 2004). Both Cu and Zn are often added to swine diets at pharmacological levels, thus exacerbating the potential negative effects on the soil.

Organic microminerals may not be as susceptible to forming unavailable complexes in the intestinal tract, such as with elevated Ca and P, and may be more digestible than the inorganic sources (Close, 1999). Thus, the use of organic minerals may abate the inhibitory effects of elevated Ca in swine diets. This experiment evaluated the effects of Ca and P level and micromineral sources on the digestibility of the essential minerals in growing pigs.


MATERIALS AND METHODS

The experimental use of animals and the procedures followed were approved by The Ohio State University Animal Care Committee (IACUC Protocol #2010AG0004).

Treatments and Diets

Treatments were comprised of 2 levels of Ca and P (CaP) and 3 trace mineral (TM) treatments arranged as a 2 × 3 factorial in a randomized complete block design with 8 replicates. Dietary TM premixes were added at the expense of corn starch (Table 1). The CaP levels were: 1) 0.65% Ca and 0.55% total P (standard CaP; Std CaP) and 2) 1.00% Ca and 0.85% total P (High CaP). Diets were formulated on a total P basis and the Ca:P ratio was approximately 1.18 in both CaP treatments. Diets were corn-soybean meal based. Calcium carbonate (chalk), phosphorus pentoxide, and dibasic sodium phosphate served as the Ca and P sources because they contain lower concentrations of ancillary microminerals than the more commonly used Ca and P sources (e.g., limestone and calcium phosphate).


View Full Table | Close Full ViewTable 1.

Composition of diets (%, as-fed basis)1

 
Item Std CaP2 High CaP2
Ingredient
    Corn 66.45 66.45
    Soybean meal, 48% CP 26.90 26.90
    Corn starch ± ±
    Choice white grease 1.00 1.00
    Phosphorus pentoxide 0.05 0.30
    Ca carbonate, chalk 1.35 2.25
    Na phosphate, dibasic 0.75 1.65
    TM premix3,4 ± ±
    Se premix–5 ± ±
    HCl solution (5.5 M) 0.50 0.50
    Cr picolinate6 0.05 0.05
    Vitamin premix7 0.25 0.25
    Antimicrobial8 0.05 0.05
Composition
    Lys, calculated 1.00 1.00
    Ca, analyzed 0.67 0.92
    P, analyzed 0.49 0.77
1± = depending on treatment, added an ingredient accordingly.
2Std = standard and CaP = Ca and P; CaP were added at the expense of corn starch to meet the Std (Ca = 0.65% and Ptotal = 0.55%) or High (Ca = 1.00% and Ptotal = 0.85%) calculated CaP treatment levels.
3Trace mineral (TM) supplements added at the expense of corn starch. At 0.25% diet provided industry levels of trace minerals: 15 mg Cu/kg, 150 mg Fe/kg, 10 mg Mn/kg, 140 mg Zn/kg, and 0.14 mg I/kg. Inorganic trace minerals were copper sulfate, ferrous sulfate, manganese oxide, and zinc sulfate. Organic trace minerals were Cu, Fe, Mn, and Zn proteinates (Bioplex, Alltech Inc., Nicholasville, KY). Iodine was provided as potassium iodate to both organic and inorganic TM treatments.
4With addition of TM premix, diets were analyzed to contain 0.15% Mg, 0.78% K, 0.17% S, 14.2 mg/kg Cu, 212 mg/kg Fe, 21.7 mg/kg Mn, 0.33 mg/kg Se, and 155 mg/kg Zn
5Selenium was added at 0.3 mg/kg of diet in TM supplemented diets at the expense of corn starch. Inorganic Se was provided as sodium selenite and organic Se was provided as Se yeast (Sel-plex, Alltech, Inc.).
6Chromium picolinate was provided at 0.20 mg/kg diet (Chromax, Prince Agri-Products, Quincy, IL).
7Vitamin premix was formulated to provide per kilogram diet: 1450 IU vitamin A (acetate), 167 IU D3 (cholecaliferol), 12 IU vitamin E (dl-α-tocopherol acetate), 0.6 mg vitamin K (menadione), 2.8 mg riboflavin, 8.9 mg pantothenic acid (d-Ca pantothenate), 11.2 mg niacin, 0.3 mg folic acid, 0.06 biotin, and 11.1 μg B12.
8Tylosin (Tylan) was added at 44 mg/kg diet (Elanco Animal Health, Greenfield, IN).

The TM treatments were: 1) no supplemented TM (Basal), with dietary microminerals comprised only from the innate minerals in the feed ingredient, 2) Basal supplemented with Cu, Fe, Mn, Se, and Zn provided in an organic form, and 3) Basal supplemented with Cu, Fe, Mn, Se, and Zn provided in an inorganic form. Organic and inorganic TM treatments were both supplemented with 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn per kilogram of diet. These inclusion rates were considered typical of commercial practices. Organic forms of Cu, Fe, Mn, and Zn were chelated to hydrolyzed soy protein (Bioplexes; Alltech Inc., Nicholasville, KY) and organic Se as a Se-yeast (Sel-Plex; Alltech Inc., Nicholasville, KY). Inorganic TM was supplied as CuSO4, FeSO4, MnO, NaSeO3, and ZnSO4.

Animals and General Procedures

Growing barrows (n = 48; BW = 44.4 ± 5.1 kg) were the progeny of Landrace × Yorkshire females and boars (PIC Boar Line 280; Birchwood Genetics, West Manchester, OH). Barrows were blocked by BW to the 6 dietary treatments and moved into stainless steel metabolism crates.

Barrows were acclimated to the crates and treatment diets for 14 d before sample collection. Pigs were fed twice daily at 0800 and 1600 h. Feed intake was equalized within replicate. The amount of feed provided was constant for the last 3 d of acclimation and throughout the collection period. The collection of feces, urine, and feed orts was for a 10-d collection period. No marker was added to the diet at the beginning or end of the extended collection period because of the possible interference with dietary minerals. Feed, urine, and feces were analyzed for mineral composition. After feedings, pigs were given water free choice. Total water intake was not recorded, and water samples were not analyzed for minerals.

Sample Collection and Analyses

During the collection period, all feces were collected twice daily. Total urine volume was recorded and an aliquot was collected and saved. The urine was not acidified to prevent the potential loss of volatile compounds. Feces and urine samples were frozen at –4°C and pooled across days of the experiment. After the collection period, total feces of each pig were weighed, mixed (Model A-120, The Hobart Mfg. Co., Troy, OH), and subsampled. Fecal subsamples were placed in Petri dishes, sealed with laboratory tape (Fisher Scientific, Pittsburg, PA) to prevent moisture loss, frozen (–4°C), and later freeze dried (Freeze Drier 5, Labconco, Kansas City, MO). Urine was filtered through glass wool and stored at –4°C until analyzed.

Treatment diets, freeze dried feces, and filtered urine were analyzed for Ca, P, Mg, K, S, Cu, Fe, Mn, and Zn using inductively coupled plasma spectrophotometer technology (PS 3000, Leeman Labs, Inc., Hudson, NH). Selenium was determined after wet ashing in nitric and perchloric acid using the fluorometric method (AOAC, 2000).

Apparent total-tract digestibility of minerals was calculated using the following formula:

Apparent retention was calculated after subtracting the total amount of mineral excreted (fecal and urine) from the amount consumed.

Statistics

The individual pig was the experimental unit for all measurements. Treatment effects were analyzed using Proc Mixed (SAS Inst., Inc., Cary, NC) using the mixed model:where Yijk is the dependent variable, μ is the grand mean, r is the random effect of the ith replicate (i = 1,…,8), C is the fixed effect of the jth CaP level (j = 1,2), T is the fixed effect of the kth TM treatment (k = 1,2,3), CT is the interaction effect of the jth CaP level and the kth TM treatment, and ε is the residual error ∼N(0, σ). A priori single df contrasts analyzed the effect of the Basal vs. both supplemented TM treatments, Standard vs. High CaP within the Basal TM treatment, organic vs. inorganic TM treatments, and the interaction between CaP level and supplemented TM form (only pigs receiving organic or inorganic TM were considered in this contrast).


RESULTS

Daily feed intake was not different among treatments (Table 2). Similarly, final BW was not affected by the CaP level or the source of TM during the study.


View Full Table | Close Full ViewTable 2.

Effects of Ca and P (CaP) levels and trace mineral (TM) treatments on growing pig performance1

 
Std CaP
High CaP
P-value
Item Basal Inorg Org Basal Inorg Org SEM Std vs. High CaP2 Inorg vs. Org3 CaP × added TM form4 Basal vs.added TM5 Basal Std vs. Basal High6
Observations 8 8 8 8 8 8
ADFI, g 1,597 1,585 1,573 1,597 1,591 1,577 64 0.83 0.43 0.94 0.29 0.99
Initial BW, kg 43.5 45.2 44.0 44.6 44.6 44.8 1.9 0.43 0.46 0.08 0.25 0.15
Final BW, kg 59.6 61.1 59.8 59.8 59.2 59.0 3.2 0.09 0.20 0.36 0.85 0.73
1CaP levels: Std (standard) = 0.65% Ca and 0.55% total P; High = 1.00% Ca and 0.85% total P. TM treatment: Basal = no added TM; Inorg = TM added in inorganic form; Org = TM added in organic form. Added TM provided per kilogram feed: 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn.
2Main effect of CaP levels (Std vs. High) across all TM treatments.
3Contrast: Org vs. Inorg added TM.
4Interaction between added TM form and CaP levels; Basal TM treatment was not considered.
5Contrast: Basal TM treatment vs. both Org and Inorg added TM.
6Contrast: Std vs. High CaP levels within the Basal TM treatment only.

Main Effects of Ca and P Levels and Trace Mineral Sources on Mineral Digestibility

The main effects of CaP on the macromineral digestibility are presented in Table 3. As expected, the quantity of Ca and P consumed increased (P < 0.01) as the dietary level of CaP increased. There was a concurrent increase in fecal Ca and P (P < 0.01) when these diets were fed but no difference in urinary Ca. There was a greater digestibility of Ca as CaP level increased (P = 0.04) but not P. The retention of Ca and P were greater (P < 0.01) as the CaP level increased.


View Full Table | Close Full ViewTable 3.

Main effects of Ca and P (CaP) levels and trace mineral (TM) treatment on macromineral digestibility

 
CaP level1
TM treatment2
Item Std High SEM Std vs. High CaP3 Basal Inorg Org SEM Inorg vs. Org4 Basal vs.added TM5
No. of pigs 24 24 16 16 16
Ca, g/d
    Intake 10.41 16.05 0.23 0.01 13.32 13.25 13.14 0.54 0.57 0.35
    Fecal 4.16 7.21 0.53 0.01 5.65 5.56 5.84 0.60 0.48 0.91
    Urine 0.03 0.03 0.01 0.96 0.03 0.03 0.03 0.01 0.71 0.73
    Retention 6.23 8.81 0.30 0.01 7.64 7.65 7.27 4.05 0.24 0.66
    ATTD,6% 60.7 55.5 2.6 0.04 58.0 59.1 57.2 3.1 0.48 0.96
P, g/d
    Intake 8.77 13.53 0.44 0.01 11.22 11.16 11.07 0.46 0.57 0.35
    Fecal 3.49 5.60 2.94 0.01 4.56 4.58 4.50 0.34 0.76 0.92
    Urine 0.11 1.34 0.10 0.01 0.93 0.60 0.64 0.12 0.77 0.01
    Retention 5.16 6.60 0.36 0.01 5.72 5.98 5.94 0.27 0.85 0.31
    ATTD, % 60.1 58.8 1.4 0.50 59.6 59.0 59.7 2.0 0.78 0.91
Mg, g/d
    Intake 3.12 3.13 0.12 0.83 3.15 3.13 3.10 0.12 0.51 0.14
    Fecal 1.54 1.67 0.09 0.10 1.58 1.64 1.60 0.11 0.68 0.58
    Urine 0.06 0.01 0.01 0.01 0.04 0.04 0.04 0.01 0.90 0.99
    Retention 1.52 1.45 0.07 0.31 1.53 1.45 1.47 0.08 0.83 0.38
    ATTD, % 50.6 46.9 1.6 0.11 49.8 47.8 48.7 2.4 0.77 0.50
K, g/d
    Intake 12.63 12.66 0.49 0.83 12.73 12.66 12.55 0.49 0.51 0.14
    Fecal 1.79 1.91 0.10 0.20 1.86 1.86 1.83 0.11 0.82 0.87
    Urine 5.43 5.49 0.40 0.85 5.54 5.65 5.19 0.45 0.25 0.68
    Retention 5.41 5.26 0.28 0.60 5.32 5.15 5.53 0.35 0.34 0.95
    ATTD, % 85.8 85.0 0.5 0.25 85.4 85.3 85.4 0.70 0.95 0.99
S, g/d
    Intake 3.17 3.18 0.12 0.82 3.19 3.18 3.15 0.12 0.50 0.13
    Fecal 0.52 0.62 0.03 0.01 0.50 0.61 0.60 0.04 0.65 0.01
    Urine 0.83 0.86 0.10 0.62 0.80 0.91 0.82 0.11 0.20 0.20
    Retention 1.71 1.82 0.08 0.04 1.88 1.66 1.74 0.09 0.28 0.01
    ATTD, % 83.5 80.7 0.4 0.01 84.2 80.9 81.1 0.6 0.79 0.01
1CaP levels: Std (standard) = 0.65% Ca and 0.55% total P; High = 1.00% Ca and 0.85% total P.
2TM treatment: Basal = no added TM; Inorg = TM added in inorganic form; Org = TM added in organic form. Added TM provided per kilogram diet: 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn.
3P-value for the main effect of CaP levels (Std vs. High) across all TM treatments.
4P-value for the contrast between Org vs. Inorg added TM.
5P-value for the contrast of the Basal treatment vs. both Org and Inorg added TM.
6ATTD = Apparent total tract digestibility.

Magnesium intake was identical for the 2 CaP levels, as well as its fecal output. Although urinary Mg was greater compared with the High CaP level when the Std CaP was fed, both urinary values were low. Potassium was not different in the intake or the output of feces and urine or digestibility values. In regards to S, the only difference was a greater fecal S excretion (P < 0.01) with the High CaP, but there was concurrently lower digestibility (P < 0.01) when the High CaP diet was fed.

The main effects of the Basal diets and the 2 TM sources on the macrominerals are also presented in Table 3. Although there was a small effect of TM treatments, an elevated urinary P (P < 0.01) was observed when the Basal diets were fed, indicating that, with addition of TM, the innate P in phytate was not as digestible. When the Basal diets were fed, S digestibility and retention were greater (P < 0.01) and fecal S was less (P < 0.01) than those fed the diets with added TM.

The main effects of CaP and TM treatments on micromineral digestibility are presented in Table 4. The 2 Basal diets, both without TM fortification, differed in the digestibility compared with the 2 TM treatments (organic and inorganic). The micromineral intake of Cu, Fe, Mn, Se, and Zn, as well as their fecal excretions, were greater (P < 0.01) when the diet was fortified with either organic or inorganic TM compared with the Basal. Urinary Cu, Se, and Zn were greater (P < 0.01) when the diet was supplemented with the organic or inorganic TM sources, whereas Fe and Mn did not differ. There were no statistical differences between the inorganic and organic TM, except where urinary Se was decreased (P < 0.01), Se retention was greater (P < 0.01), and Fe digestibility and retention were greater (P < 0.04) when Se was provided in the organic form.


View Full Table | Close Full ViewTable 4.

Main effects of C and P (CaP) level and trace mineral (TM) treatments on micromineral digestibility

 
CaP level1
TM treatment2
Item Std. High SEM Std vs. High CaP3 Basal Inorg Org SEM Inorg vs. Org4 Basal vs. Added TM5
No. of pigs 24 24 16 16 16
Cu, mg/d
    Intake 27.52 27.59 1.45 0.90 11.81 35.58 35.27 1.60 0.53 0.01
    Fecal 20.73 21.59 0.98 0.51 6.42 29.40 27.65 1.54 0.37 0.01
    Urine 0.05 0.09 0.02 0.04 0.05 0.10 0.11 0.02 0.24 0.01
    Retention 6.75 5.88 0.67 0.36 5.31 6.06 7.56 1.11 0.29 0.06
    ATTD,6% 29.1 26.9 2.5 0.38 44.4 17.6 22.1 3.2 0.20 0.01
Fe, mg/d
    Intake 334.9 335.7 16.9 0.90 167.6 420.8 417.4 17.9 0.53 0.01
    Fecal 214.0 241.9 14.2 0.11 101.3 303.7 278.8 20.7 0.32 0.01
    Urine 2.20 1.60 0.50 0.29 1.90 2.00 1.80 0.90 0.26 0.99
    Retention 109.4 118.7 17.2 0.32 64.4 125.1 152.3 18.7 0.04 0.01
    ATTD, % 38.0 35.1 4.1 0.55 43.6 29.3 36.8 5.1 0.03 0.02
Mn, mg/d
    Intake 33.19 33.27 0.95 0.89 22.82 38.58 38.27 1.10 0.71 0.01
    Fecal 27.90 29.41 1.24 0.31 17.86 33.97 34.13 1.82 0.94 0.01
    Urine 0.04 0.02 0.01 0.02 0.03 0.03 0.04 0.01 0.58 0.92
    Retention 6.94 4.89 0.74 0.06 4.81 5.23 7.71 1.15 0.11 0.07
    ATTD, % 21.6 16.10 2.1 0.07 21.7 14.1 20.7 3.0 0.11 0.14
Se, mg/d
    Intake 0.50 0.50 0.03 0.91 0.19 0.67 0.66 0.03 0.53 0.01
    Fecal 0.12 0.12 0.01 0.96 0.04 0.17 0.15 0.02 0.16 0.01
    Urine 0.12 0.13 0.01 0.84 0.02 0.24 0.11 0.02 0.01 0.01
    Retention 0.26 0.26 0.02 0.89 0.13 0.25 0.40 0.02 0.01 0.01
    ATTD, % 76.5 75.9 2.7 0.80 77.3 73.9 77.5 3.8 0.10 0.64
Zn, mg/d
    Intake 189.9 190.4 11.0 0.92 42.8 264.9 262.7 12.2 0.53 0.01
    Fecal 157.2 159.2 7.2 0.62 32.1 222.4 215.5 9.1 0.65 0.01
    Urine 1.4 1.4 0.2 0.71 1.0 1.6 1.7 0.2 0.18 0.01
    Retention 35.1 29.6 4.5 0.38 10.5 40.9 45.6 7.3 0.62 0.01
    ATTD, % 23.5 16.4 2.6 0.03 25.2 16.2 18.5 3.4 0.50 0.05
1CaP levels: Std (standard) = 0.65% Ca and 0.55% total P; High = 1.00% Ca and 0.85% total P.
2TM treatment: Basal = no added TM; Inorg = TM added in inorganic form; Org = TM added in organic form. Added TM provided per kilogram diet: 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn.
3P-value for the main effect of CaP levels (Std vs. High) across all TM treatments.
4P-value for the contrast between Org vs. Inorg added TM.
5P-value for the contrast of the Basal treatment vs. both Org and Inorg added TM.
6ATTD = Apparent total tract digestibility.

Interactive Effects of Ca and P Levels and Trace Mineral Sources on Mineral Digestibility

The interactive effects of both the Std and High CaP levels across all TM treatments on macromineral digestibilities are reported in Table 5. As expected, the High CaP resulted in a greater intake of Ca and P (P < 0.01) as well as greater fecal excretion of both minerals. The apparent total tract digestibility of Ca was greater (P < 0.01) with the Std CaP treatments vs. the High CaP treatments. There was no difference between treatments on Mg and K digestibilities. The interaction effect of the 2 CaP and TM treatments was not statistically significant. There was no effect of inorganic and organic TM sources on macromineral digestibilities.


View Full Table | Close Full ViewTable 5.

Interactive effects of Ca and P (CaP) levels and trace mineral (TM) treatment on macromineral digestibility

 
CaP1:
Std CaP
High CaP
P-values
Item TM2: Basal Inorg Org Basal Inorg Org SEM Std vs. High CaP3 Inorg vs. Org4 CaP × added TM form5 Basal vs.Added TM6 Basal Std vs. Basal High7
No. of pigs 8 8 8 8 8 8
Ca, g/d
    Intake 10.49 10.42 10.34 16.14 16.08 15.94 0.57 0.01 0.57 0.86 0.35 0.01
    Fecal 4.30 4.09 4.09 7.00 7.04 7.59 0.71 0.01 0.48 0.48 0.91 0.01
    Urine 0.03 0.03 0.03 0.03 0.04 0.03 0.01 0.96 0.71 0.44 0.73 0.40
    Retention 6.15 6.30 6.22 9.12 9.00 8.32 0.40 0.01 0.24 0.35 0.66 0.01
    ATTD,8% 59.1 61.3 61.6 56.9 56.9 52.7 3.9 0.04 0.48 0.42 0.96 0.65
P, g/d
    Intake 8.83 8.77 8.70 13.60 13.55 13.43 0.48 0.01 0.57 0.86 0.35 0.01
    Fecal 3.37 3.68 3.43 5.75 5.47 5.56 0.41 0.01 0.76 0.53 0.92 0.01
    Urine 0.20 0.07 0.06 1.67 1.13 1.21 0.14 0.01 0.77 0.70 0.01 0.01
    Retention 5.26 5.02 5.21 6.18 6.95 6.66 0.34 0.01 0.85 0.32 0.31 0.04
    ATTD, % 61.4 58.1 60.9 57.8 60.0 58.6 2.9 0.50 0.78 0.44 0.91 0.24
Mg, g/d
    Intake 3.15 3.12 3.10 3.15 3.13 3.11 0.13 0.83 0.51 0.95 0.14 0.98
    Fecal 1.49 1.64 1.49 1.67 1.64 1.70 0.13 0.10 0.68 0.32 0.58 0.15
    Urine 0.05 0.07 0.06 0.02 0.01 0.01 0.02 0.01 0.90 0.98 0.99 0.16
    Retention 1.60 1.42 1.54 1.46 1.48 1.40 0.11 0.31 0.83 0.23 0.38 0.32
    ATTD, % 52.3 47.5 52.1 47.2 48.1 45.3 3.4 0.11 0.77 0.43 0.50 0.13
K, g/d
    Intake 12.73 12.64 12.54 12.73 12.68 12.57 0.52 0.83 0.51 0.95 0.14 0.97
    Fecal 1.79 1.78 1.80 1.93 1.93 1.86 0.14 0.20 0.82 0.67 0.87 0.45
    Urine 5.66 5.74 4.90 5.43 5.55 5.49 0.54 0.85 0.25 0.32 0.68 0.60
    Retention 0.53 5.11 0.58 5.37 5.20 5.21 0.45 0.60 0.34 0.35 0.95 0.78
    ATTD, % 85.9 85.9 85.5 84.9 84.8 85.3 0.9 0.25 0.95 0.62 0.99 0.43
S, g/d
    Intake 3.19 3.17 3.15 3.19 3.18 3.15 0.12 0.82 0.50 0.95 0.13 0.99
    Fecal 0.46 0.57 0.54 0.55 0.65 0.65 0.04 0.01 0.65 0.47 0.01 0.07
    Urine 0.82 0.92 0.76 0.79 0.91 0.87 0.12 0.62 0.20 0.41 0.20 0.65
    Retention 1.92 1.69 1.85 1.85 1.63 1.63 0.11 0.04 0.28 0.30 0.01 0.30
    ATTD, % 85.6 82.1 82.9 82.8 79.8 79.4 0.8 0.01 0.79 0.43 0.01 0.01
1CaP levels: Std (standard) = 0.65% Ca & 0.55% total P; High = 1.00% Ca & 0.85% total P.
2TM treatment: Basal = no added trace mineral; Inorg = TM added in inorganic form; Org = TM added in organic form. Added TM provided per kilogram diet: 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn.
3Main effect of CaP levels (Std vs. High) across all TM treatments.
4Contrast: Org vs. Inorg added TM.
5Interaction between added TM and CaP levels; Basal trace mineral treatment was not considered.
6Contrast: Basal TM treatment vs. both Org and Inorg added TM.
7Contrast: Std vs. High CaP levels within the Basal TM.
8ATTD = Apparent total tract digestibility.

The effect of the Basal diets, compared with the 2 TM treatments, was generally not statistically significant except for S. Fecal S was decreased (P < 0.01) and retention and digestibility of S were greater (P < 0.01) in the non-fortified Basal diet. Comparison of the 2 Basal diets, the Std CaP and the High CaP levels without TM fortification, indicated that the intake, fecal, and retention of Ca and P were greater (P < 0.01) when the High CaP Basal diet was fed. The effect on the other macrominerals was small and not statistically significant, except for S, which had somewhat lower apparent digestibility with the High CaP (P < 0.01).

The interactive effect of CaP levels in the Basal vs. the TM treatments on micromineral digestibility values is reported in Table 6. None of the micromineral digestibilities differed by CaP levels, except that the apparent digestibility of Zn was decreased (P = 0.03) when the High CaP Basal diet was fed. There was a less (P = 0.02) urinary Mn when the High CaP Basal diet was fed, but the difference was small and inconsequential. The only statistically significant difference with the inorganic and organic TM was Se and Fe where organic TM had a greater Se retention (P < 0.01) and less urinary Se (P < 0.01) and greater Fe digestibility and retention (P < 0.04).


View Full Table | Close Full ViewTable 6.

Interactive effects of Ca and P (CaP) levels and trace mineral (TM) treatment on micromineral digestibility

 
CaP1:
Std CaP
High CaP
P-values
Item TM2: Basal Inorg Org Basal Inorg Org SEM Std vs. High CaP3 Inorg vs. Org4 CaP × added TM form5 Basal vs.Added TM6 Basal Std vs. Basal High7
No.of pigs 8 8 8 8 8 8 -
Cu, mg/d
    Intake 11.81 35.50 35.24 11.81 35.64 35.31 1.69 0.90 0.53 0.95 0.01 0.99
    Fecal 6.06 29.53 26.59 6.78 29.28 28.71 1.74 0.51 0.37 0.54 0.01 0.25
    Urine 0.03 0.05 0.09 0.05 0.10 0.11 0.03 0.04 0.24 0.55 0.01 0.30
    Retention 5.63 6.00 8.63 5.00 6.13 6.50 1.57 0.36 0.29 0.42 0.06 0.31
    ATTD,8% 45.4 16.8 25.6 43.3 18.4 18.9 4.2 0.38 0.20 0.25 0.01 0.55
Fe, mg/d
    Intake 167.6 421.6 417.8 167.6 420.1 417.0 19.3 0.90 0.53 0.95 0.01 0.99
    Fecal 98.1 297.1 246.8 104.4 310.4 310.8 28.3 0.11 0.32 0.31 0.01 0.65
    Urine 2.7 2.3 1.7 1.1 1.8 1.8 1.3 0.29 0.26 0.28 0.99 0.38
    Retention 66.8 120.8 168.6 62.1 126.5 136.5 20.8 0.32 0.04 0.12 0.01 0.68
    ATTD, % 38.6 28.2 40.4 36.0 30.1 33.2 8.7 0.55 0.03 0.14 0.02 0.82
Mn, mg/d
    Intake 22.82 38.51 38.22 22.82 38.65 38.32 1.21 0.89 0.71 0.98 0.01 0.99
    Fecal 16.90 34.31 32.49 18.83 33.63 35.77 2.48 0.31 0.94 0.35 0.01 0.11
    Urine 0.05 0.04 0.05 0.02 0.03 0.03 0.01 0.02 0.58 0.48 0.92 0.11
    Retention 5.88 4.73 10.22 3.78 5.72 5.20 1.61 0.06 0.11 0.06 0.07 0.05
    ATTD, % 25.4 12.3 26.9 18.0 15.8 14.5 4.2 0.07 0.11 0.06 0.14 0.08
Se, mg/d
    Intake 0.19 0.66 0.66 0.19 0.67 0.66 0.03 0.91 0.53 0.95 0.01 0.99
    Fecal 0.04 0.17 0.15 0.05 0.17 0.14 0.02 0.96 0.16 0.79 0.01 0.64
    Urine 0.01 0.23 0.12 0.02 0.26 0.11 0.02 0.84 0.01 0.48 0.01 0.42
    Retention 0.14 0.26 0.39 0.13 0.24 0.41 0.04 0.89 0.01 0.43 0.01 0.50
    ATTD, % 78.7 74.0 77.0 75.9 73.8 78.1 4.9 0.80 0.10 0.77 0.64 0.66
Zn, mg/d
    Intake 42.8 264.4 262.5 42.8 265.3 263.0 13.8 0.92 0.53 0.95 0.01 0.99
    Fecal 29.5 225.5 207.6 34.8 219.3 223.5 16.9 0.62 0.65 0.47 0.01 0.08
    Urine 1.2 1.5 1.7 0.8 1.7 1.8 0.2 0.71 0.18 0.67 0.01 0.07
    Retention 14.5 37.6 53.3 6.5 44.3 37.9 10.3 0.38 0.62 0.24 0.01 0.03
    ATTD, % 34.3 14.6 21.7 16.2 17.7 15.4 5.3 0.03 0.50 0.18 0.05 0.02
1CaP levels: Std (standard) = 0.65% Ca & 0.55% total P; High = 1.00% Ca & 0.85% total P.
2TM treatment: Basal = no added TM; Inorg = TM added in inorganic form; Org = TM added in organic form. Added TM provided per kilogram diet: 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn.
3Main effect of CaP levels (Std vs. High) across all TM treatments.
4Contrast: Org vs. Inorg added TM.
5Interaction between added trace mineral form and CaP levesl; Basal TM treatment was not considered.
6Contrast: Basal TM treatment vs. both Org and Inorg added TM.
7Contrast: Std vs. High CaP levels within the Basal TM treatments.
8ATTD = Apparent total tract digestibility.


DISCUSSION

For the past few decades, there has been controversy whether organic trace minerals were equivalent to inorganic minerals and, therefore, what factors would enhance or limit the effectiveness of organic minerals in swine diets. We studied the effects of these dietary mineral sources on their digestibility, along with a non-fortified TM Basal diet. A summary of the apparent digestibilities of the macro- and microminerals from these dietary variables compiled from Tables 5 and 6 is presented in Table 7.


View Full Table | Close Full ViewTable 7.

Summary of apparent total tract digestibility of macro- and microminerals in growing swine (%)

 
TM1: Basal
Inorg TM
Org TM
Item CaP2: Std High SEM P-value Std High SEM P-value Std High SEM P-value
Macromerals
    Ca 59.1 56.9 3.1 0.65 61.3 56.9 2.5 0.18 61.6 52.7 3.0 0.07
    P 61.4 57.8 1.5 0.23 58.1 60.0 1.6 0.57 60.9 58.6 2.0 0.59
    Mg 52.3 47.2 1.6 0.13 47.5 48.1 2.0 0.87 52.1 45.3 2.4 0.18
    K 85.9 84.9 0.7 0.43 85.9 84.8 0.7 0.44 85.5 85.3 0.5 0.74
    S 85.6 82.8 0.5 0.01 82.1 79.8 0.5 0.05 82.9 79.4 0.6 0.01
    avg 68.9 65.9 67.0 65.9 68.6 64.3
Microminerals
    Cu 45.4 43.3 2.4 0.55 16.8 18.4 2.5 0.70 25.6 18.9 3.2 0.26
    Fe 38.6 36.0 5.1 0.66 28.2 30.1 4.0 0.61 40.4 33.2 4.1 0.16
    Mn 25.4 18.0 2.1 0.08 12.3 15.8 2.5 0.50 26.9 14.5 3.1 0.08
    Se 78.7 75.9 3.8 0.66 74.0 73.8 2.7 0.97 77.0 78.1 2.1 0.49
    Zn 34.3 16.2 3.4 0.02 14.6 17.7 2.3 0.44 21.7 15.4 3.0 0.28
    avg 44.5 37.9 29.2 31.2 38.3 32.0
1TM treatment: Basal = no added TM; Inorg = TM added in inorganic form; Org = TM added in organic form. Added TM provided per kilogram diet: 15 mg Cu, 150 mg Fe, 10 mg Mn, 0.3 mg Se, and 140 mg Zn.
2CaP levels: Std (standard) = 0.65% Ca and 0.55% total P; High = 1.00% Ca and 0.85% total P.

Our summary demonstrated that an increased CaP level had the greatest effect on mineral digestibilities than any other experimental variable. Comparing the CaP levels in the 2 Basal diets, all of the macrominerals were, on average, 3% lower when the High CaP basal diet was fed, in which the response attributed more to Ca than P. This also seemed to have resulted in a greater digestibility of the organic than the inorganic microminerals. The micromineral digestibilities of organic TM sources were greater when the Std CaP was fed than the High CaP level. As in macrominerals, the High CaP diet resulted in reduced micromineral digestibilities, and the addition of inorganic or organic TM to the High CaP diet resulted in a reduced macromineral digestibility. The organic microminerals were more digestible than the inorganic microminerals, differing by an average of 5% for both CaP levels (30 vs. 35%).

Evident in this summary table also demonstrated that the innate microminerals in the Basal diets were lowered when the High CaP diet was fed. Although there was no apparent effect of CaP level on the microminerals, their digestibilities were greater when the organic microminerals were fed. The organic TM was affected by CaP level with the ATTD being reduced by approximately 6% when the High CaP basal diet was fed.

Other factors can affect the digestibility of the macro- and microminerals. Phytase, known to affect the digestibility of P, was not added to our diets because we wanted to evaluate the effectiveness of the experimental variables without the interference of this exogenous enzyme. Phytase has been a common addition to swine diets for several years. How the digestion from the addition of phytase on microminerals in different diet formulations has yet to be thoroughly tested.

Results in our study for Ca and P digestibility differ from those of Stein et al. (2011) who reported that the dietary Ca level did not affect the apparent digestibility of Ca. They also reported that the apparent digestibility of P declined as Ca level increased. But, the study of Stein et al. (2011) used a consistent level of dietary P, which means that the Ca to P ratio changed as the Ca level changed. The Ca to P ratio was similar in the in the present study, which may account for the discrepancy.

In conclusion, increasing dietary CaP decreased the digestibility of Ca, S, and Zn. Although it is common practice to supplement the diet with excess of Ca and P, as well as the micromnerals, this practice could affect the digestibility of the microminerals. The digestibility of the innate micromineral in a corn-soybean meal based diet averaged 45%. These data provide evidence that an appreciable amount of these innate microminerals are available to the pig via the digestive process. The digestibility of Cu, Fe, and Zn declined as dietary inclusion levels of CaP increased. Phosphorus digestibility did not change when the P inclusion level in the diet increased from 0.55 to 0.85% total P when the Ca to P ratio was maintained at approximately 1.18.

 

References

Footnotes


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