- Email: [email protected]
Response of Yearling Quarter Horses to Varying Concentrations of Dietary Calcium1
Animal Scientist 18 (2002):277–281 CThe ASE SProfessional TUDY: Calcium Metabolism in Yearling Quarter Horses
277
CQuarter S : Response of Yearling Horses to Varying ASE TUDY
Concentrations of Dietary Calcium1 A. D. MOFFETT2 , PAS, S. R. COOPER, PAS, D. W. FREEMAN, PAS, and H. T. PURVIS, PAS Oklahoma State University, Department of Animal Science, Stillwater, OK 74078
Abstract Fifteen yearling Quarter Horses were used in a split-plot designed experiment to determine the effects of three concentrations of Ca on mineral metabolism, bone density, and parameters of growth. Horses were blocked by sex and BW and randomly assigned to one of three dietary treatments that were formulated to contain 115, 100, and 85% of NRC (10) requirements for Ca. Diets consisted of ground corn, soybean meal, and cottonseed hulls fed at a 70:30 with native prairie grass hay at 2.5% BW. The 25wk trial consisted of three 72-h collection periods at d 0 (Period 1), d 90 (Period 2), and d 180 (Period 3) during which complete urine and fecal collections were taken. Additionally, radiographs of the left front cannon were taken 1 wk prior to each collection for determination of bone density. Data were analyzed with horse and treatment as main effects. Results
from this study demonstrated an increased Ca retention with increased intake during all three periods. There was, however, no radiographic evidence of treatment effect on bone density. (Key Words: Calcium, Bone Density, Growth, Yearling Horses.)
Introduction
Minerals are essential to many functions in the body, ranging from the formation of structural components to enzymatic cofactors and energy transfer. Mineral research has been of great interest to the horse industry, especially with regard to growing horses. Calcium and phosphorus requirements for growing horses were estimated from research performed in ponies (8, 18, 20, 21). Krook and Maylin (9) reported that a nutrient is generally required in inverse proportion to BW. Therefore, the data reported from 200-kg ponies may not be applicable to 500-kg horses when expressed as milligrams of nutrient per kilogram of BW. Consequently, the objective of this experiment was 1Approved for publication by the director, to evaluate the effects of feeding Oklahoma Agriculture Experiment Station. various levels of Ca on mineral 2To whom correspondence should be admetabolism, bone density, and dressed: [email protected] parameters of growth in yearling Quarter Horses.
Materials and Methods Fifteen yearling Quarter Horses were used in a split-plot designed experiment to evaluate the response of Ca metabolism, bone density, and parameters of growth to varying concentrations of dietary Ca. Horses were blocked by sex and BW and then randomly assigned to one of three treatments (high, basal, and low). Horses were fed approximately 2.5% of BW/d in total ration. Experimental diets consisted of corn, soybean meal, and cottonseed hulls fed at 70:30 with prairie grass hay (Table 1). Diets were formulated to contain Ca concentrations at 115% (high; H), 100% (basal; B), and 85% (low; L) of NRC requirements. The 25-wk trial consisted of three 72-h collection periods at d 0 (Period 1; 12 mo of age), d 90 (Period 2; 15 mo of age), and d 180 (period 3; 18 mo of age) during which complete urine and fecal collections were taken. Total urine was collected via urine harnesses. Multiple fecal grab samples were also taken during the 72-h collection period. Grab samples were immediately frozen for later mineral analysis. Daily aliquots of feces and urine were taken to make a composite from which subsequent mineral analyses were performed. Fecal mineral analysis was performed
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Diets H, B, and L. Dry matter digestibility ranged from 58 to 69% across all periods and treatments. During Periods 1 and 2, DMD did not differ Treatment significantly between treatments. However, DMD was less (P<0.05) for Item High Ca Basal Ca Low Ca horses consuming Diet L (58%) than for horses consuming Diets B (67%) Ingredient, % and H (65%) during Period 3. The Ground corn 40.50 40.10 39.50 decreased DMD of horses consuming Soybean meal 14.00 14.20 13.60 Diet L during Period 3 might have Cottonseed hulls 14.60 15.00 16.40 been due to the numerical decrease in a 0.30 0.30 0.30 TM salt DMI and increased FO. Limestone 0.50 0.40 0.20 The DMD values observed in the Dicalcium phosphate 0.10 –– –– present study are greater than those Prairie grass hay 30.00 30.00 30.00 Nutrient reported by others (1, 3) who obDEb, Mcal/kg 2.80 2.81 2.79 served values ranging from 49 to 50% CP, % 15.4 15.1 14.5 and 48 to 52% in yearling and Ca, % 0.48 0.42 0.32 mature horses, respectively. The P, % 0.34 0.31 0.30 difference in the digestibility values may be the result of taking total fecal aTM = Trace mineral. collections in the present study bCalculated from NRC tables. compared with the use of chromic oxide as an external marker in the previous studies. Patterson et al. (16) using Inductively Coupled Plasma DM digestibility (DMD) are shown in demonstrated that calculated values Spectroscopy (ICAP 61®; Spectro Table 2. Urine volume was not (utilizing chromic oxide) for FO are Analysis Instruments, Fitchburg, significantly different across treatgreater when compared with total MA). Urinary Ca and P were anaments for all three periods. During fecal collections. lyzed using a Vitros 250® analyzer Periods 1, 2, and 3 of the trial, no Ca Balance. Data for Ca intake, (Johnson & Johnson Clinical Diagdifference (P>0.05) was detected in excretion, and retention are shown nostics, Inc., Rochester, NY). Weekly DMI and FO for horses consuming in Table 3. Horses consuming Diets H growth parameters were taken during the 25-wk trial, which included BW, withers, hip, hock, shoulder, and TABLE 2. Effects of varying concentrations of Ca on DMI, daily fecal carpus height and heart girth circumoutput (FO), and DM digestibility (DMD)a. ference. Additionally, radiographs Treatment (lateral-medial and dorsal-palmar) of each yearling’s left front thirdPeriod High Ca Basal Ca Low Ca SEMb metacarpal were taken 1 wk prior to each collection period to determine the radiographic bone aluminum 1 equivalence (RBAE). DMI, g/d 5,862.96 6,036.38 6,043.66 323.75 FO, g/d 2,388.84 2,547.76 2,460.06 192.39 Data were analyzed using the DMD, % 59.45 57.74 59.13 2.14 general linear models procedure of 2 SAS (17) with horse and treatment as DMI, g/d 6,849.04 6,938.96 6,580.28 323.75 main effects. Least squares means FO, g/d 2,078.20 2,308.74 2,355.22 192.39 were calculated for each treatment DMD, % 69.38 66.62 64.20 2.14 within a given period, and the p-diff 3 procedure of SAS was used to test for DMI, g/d 7,864.40 8,123.20 7,533.00 323.75 differences between treatment means. FO, g/d 2,698.60 2,660.60 3,104.80 192.39
TABLE 1. Composition of treatment diets (as fed basis).
DMD, %
Results and Discussion DMI, Fecal Output, and DM digestibility. Data for daily DMI, fecal output (FO), urine volume, and
aValues
65.40c
67.20c
58.00d
are least squares means.
bValues are average standard errors. c,dMeans
within a row with different superscripts differ (P<0.05).
2.14
279
CASE STUDY: Calcium Metabolism in Yearling Quarter Horses
TABLE 3. Effects of varying concentrations of Ca on mineral balancea. Treatment High Ca
Basal Ca
Low Ca
SEMb
Intake, g/d Fecal, g/d Urine, g/d Balance, g/d
28.13c 17.13c 2.92 8.07c
25.35c 15.47c 2.97 6.90c
19.33d 11.73d 4.86 2.74d
1.35 1.33 0.65 1.69
Intake, g/d Fecal, g/d Urine, g/d Balance, g/d
32.87c 18.56c 1.45 12.86c
29.14c 17.66c 1.54 9.93cd
21.05d 12.51d 1.04 7.49d
1.35 1.33 0.65 1.69
Intake, g/d Fecal, g/d Urine, g/d Balance, g/d
37.75c 22.25c 3.85 11.64fg
34.12c 17.21d 3.30 13.59f
24.10d 12.82e 4.46 6.82g
1.57 1.33 0.65 2.32
Period 1
2
3
aValues
are least squares means.
bValues are average standard errors. c,d,eMeans f,gMeans
within a row with different superscripts differ (P<0.05). within a row with different superscripts differ (P<0.10).
and B had a significantly greater intake and fecal excretion of Ca than horses fed Diet L during Periods 1 and 2. During Period 3, similar results were observed for Ca intake, but fecal excretion of Ca decreased significantly between the Diets H (22.25 g/ d), B (17.21 g/d), and L (12.82 g/d). Urinary excretion of Ca was not different (P>0.05) between horses consuming Diets H, B, and L during all three periods. During Period 1, retention of Ca was greater (P<0.05) in horses consuming Diets H and B vs Diet L. Furthermore, those horses fed Diet H retained more Ca (P<0.05) than horses fed Diet L during Period 2. During Period 3, there was a tendency (P<0.10) for horses consuming Diet B to have a greater Ca balance than those fed Diet L. Horses consuming Diet H also had a numerically greater retention of Ca than those fed Diet L, although not significant. The increased retention of Ca in horses consuming Diet H during Periods 1 and 2 is similar to previous studies that have shown an en-
hanced Ca balance in horses and ponies consuming supplemental Ca (2, 13, 14, 18, 19). Schryver et al. (18, 19) observed that as Ca intake increased from 29 mg/kg BW on the low diet to 242 mg/kg BW on the high, retention of Ca increased from –7.5 to 56 mg/kg BW, respectively. Bone Density. The effect of varying levels of Ca on bone density of yearling horses is reported in Table 4. The RBAE of the lateral cortex was similar (P>0.05) between treatments for Periods 1 and 3. However, there was a tendency (P<0.10) for horses fed Diet H to have a greater RBAE for the lateral cortex when compared with horses fed Diet B during Period 2. These results were similar to those of Nielsen et al. (13, 14), who reported a tendency for the RBAE of the lateral cortex of 2-yr-old horses to increase in the high group (high Ca, high training level) while the control group (adequate Ca, controlled training level) remained unchanged.
TABLE 4. Effects of varying concentrations of Ca on bone density of yearling horsesa. Treatment Period
High Ca
Basal Ca
Low Ca
SEM b
1 Lateral RBAEc (mm Al) Medial RBAE (mm Al) Dorsal RBAE (mm Al) Palmar RBAE (mm Al) Total RBAE (mm2 Al)
19.40 19.60 19.00 18.40 342.51
21.20 21.60 18.60 18.00 551.82
22.60 22.20 22.40 22.00 530.04
1.87 1.85 1.84 1.82 112.45
Lateral RBAE (mm Al) Medial RBAE (mm Al) Dorsal RBAE (mm Al) Palmar RBAE (mm Al) Total RBAE (mm2 Al)
26.60d 26.60 20.60 19.40 346.09
21.60e 22.40 21.80 21.40 424.07
23.60de 23.80 22.20 21.80 512.75
1.87 1.85 1.84 1.82 112.45
Lateral RBAE (mm Al) Medial RBAE (mm Al) Dorsal RBAE (mm Al) Palmar RBAE (mm Al) Total RBAE (mm2 Al)
24.40 24.00 20.20 19.40 417.47
22.20 21.70 21.60 21.00 389.86
23.80 23.60 22.40 21.60 388.60
1.87 1.85 1.84 1.82 112.45
2
3
aValues
are least squares means.
bValues are average standard errors. cRBAE
= Radiographic bone aluminum equivalence. within a row with different superscripts differ (P<0.10).
d,eMeans
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Moffett et al.
Savoy, IL.
TABLE 5. Mean response of growth parameters in yearling horses fed varying concentrations of Caa,b. Treatment Growth parameter
High Ca
Basal Ca
Low Ca
SEM c
BW, kg ADG, kg/d Wither height, cm Hip height, cm Shoulder height, cm Hock height, cm Knee height, cm Heart girth, cm
355.42 0.39 137.05 141.47 94.81 51.58 41.16 159.12
371.39 0.40 138.22 143.64 95.24 51.96 41.34 158.55
370.40 0.41 141.17 145.22 96.50 53.54 43.03 160.04
17.68 0.015 1.55 1.66 1.26 0.75 0.77 2.81
aValues
are least squares means.
cValues are average standard errors.
Implications Results from this study demonstrated that Ca balance was not significantly enhanced by supplemental Ca above (115%) NRC recom-
4. Gibbs, P. G., S. H. Sigler, and T. B. Goehring. 1989. Influence of diet on growth and development of yearling horses. J. Equine Vet. Sci. 9(4):215. 5. Hiney, K., G. D. Potter, P. G. Gibbs, and S. M. Bloomfield. 2000. Response of serum biochemical markers of bone metabolism to training in the juvenile racehorse. J. Equine Vet. Sci. 20:851. 6. Hintz, H. F., H. F. Schryver, and J. E. Lowe. 1986. Calcium for pregnant mares and growing horses. Equine Pract. 8:5. 7. Jordan, R. M., V. S. Myers, B. Yoho, and F. Spurrell. 1973. A note on calcium and phosphorus levels fed to ponies during growth and reproduction. In Proc. 3rd Equine Nutr. Res. Symp., Gainesville, FL. p 55. Equine Nutr. Physiol. Soc., Savoy, IL.
bMeans do not differ (P>0.05) between treatments.
The RBAE of the medial, dorsal, and palmar cortices were not different (P>0.05) between treatments during any period. Nielsen et al. (13, 14) observed similar results in 2-yr olds in training in which no difference in RBAE were noted between treatments (high vs control). Concerning total RBAE, there were no significant differences between treatments for all periods. Similar results were reported in 2-yr olds in training in which no significant differences in total RBAE values were observed between treatments (high vs control) (6, 14). Parameters of Growth. Mean values for all variables of growth are shown in Table 5. There were no significant differences between treatment means for BW, withers, hip, hock, shoulder, and carpus height and heart girth circumference for the 25-wk trial. These results are similar to work performed by Gibbs et al. (5) who varied protein, Ca, and P levels and observed no significant difference in ADG, heart girth circumference, and wither height for yearlings.
3. Cooper, S. R., D. R. Topliff, D. W. Freeman, J. E. Breazile, and R. D. Geisert. 2000. Effects of dietary cation-anion difference in weanling horses. J. Equine Vet. Sci. 20:30.
mended levels. Conversely, when horses were fed low (85% of NRC) Ca diets, the retention of Ca was significantly reduced. Despite this decreased Ca balance, no significant differences were detected between treatments in bone density or skeletal growth parameters. These data therefore support the current NRC recommendations for Ca intake in yearling horses and suggest that feeding Ca in excess of these recommended levels may not be of benefit to skeletal growth and mineralization in yearling horses.
Literature Cited 1. Baker, L. A., D. R. Topliff, D. W. Freeman, R. G. Teeter, and B. Stoecker. 1998. The comparison of two forms of sodium in the dietary cation-anion difference equation: Effects on mieral balance in sedentary horses. J. Equine Vet. Sci. 18:389. 2. Buchholz, M. A., L. A. Baker, J. L. Pipkin, M. J. Mansell, L. W. Greene, J. C. Haliburton, and R. C. Bachman. 1999. The effect of calcium and phosphorus supplementation, inactivity and subsequent aerobic training on mineral balance of varying ages of horses. In Proc. 16th Equnie Nutr. Physiol. Symp., Raleigh, NC. p 12. Equine Nutr. Physiol. Soc.,
8. Krook, L., and G. A. Maylin. 1988. Fractures in Thoroughbred race horses. Cornell Vet. 98:1. 9. National Academy of Science. 1989. Nutrient Requirements of Horses. (5th Ed.). National Research Council, Washington, D.C. 10. Nielsen, B. D. 1992. Training distance to failure and density of the third metacarpal in young racing Quarter Horses fed sodium zeolite A. M.S. Thesis. Texas A&M Univ., College Station, Texas. 11. Nielsen, B. D., G. D. Potter, E. L. Morris, T. W. Odom, D. M. Senor, J. A. Reynolds, W. B. Smith, and M. T. Martin. 1997. Changes in the third metacarpal and frequency of bone injuries in young Quarter Horses during race training-observations and theoretical considerations. J. Equine Vet. Sci. 17:541. 12. Nielsen, B. D., G. D. Potter, L. W. Greene, E. L. Morris, M. Murray-Gerzik, W. B. Smith, and M. T. Martin. 1998. Characterization of changes related to mineral balance and bone metabolism in the young racing Quarter Horse. J. Equine Vet. Sci. 18:190. 13. Nielsen, B. D., G. D. Potter, L. W. Greene, E. L. Morris, M. Murray-Gerzik, W. B. Smith, and M. T. Martin. 1998. Response of yearling horses in training to varying concentrations of dietary calcium and phosphorus. J. Equine Vet. Sci. 18:397. 14. Patterson, D. P., S. R. Cooper, D. W. Freeman, and R. G. Teeter. 2001. Estimation of fecal output and dry matter digestibility using various chromic oxide marker methods in the horse. In Proc. 17th Equine Nutr. Physiol. Symp., Lexington, KY. p 402. Equine Nutr. Physiol. Soc., Savoy, IL. 15. SAS. 1999. SAS User’s Guide: Statistics. SAS Institute Inc., Cary, NC. 16. Schryver, H. F., P. H. Craig, and H. F. Hintz. 1970. Calcium metabolism in ponies fed varying levels of calcium. J. Nutr. 100:955.
CASE STUDY: Calcium Metabolism in Yearling Quarter Horses
17. Schryver, H. F., P. H. Craig, H. F. Hintz, D. E. Hogue, and J. E. Lowe. 1970. The site of calcium absorption in the horse. J. Nutr. 100:1127. 18. Schryver, H. F., H. F. Hintz, and P. H. Craig. 1971. Calcium metabolism in ponies
fed a high phosphorus diet. J. Nutr. 101:259. 19. Schryver, H. F., H. F. Hintz, and P. H. Craig. 1971. Phosphorus metabolism in ponies fed varying levels of phosphorus. J. Nutr. 101:1257.
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20. Schryver, H. F., H. F. Hintz, and J. E. Lowe. 1978. Calcium metabolism, body composition and sweat losses of exercised horses. Am. J. Vet. Res. 39:245.
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CQuarter S : Response of Yearling Horses to Varying ASE TUDY
Concentrations of Dietary Calcium1 A. D. MOFFETT2 , PAS, S. R. COOPER, PAS, D. W. FREEMAN, PAS, and H. T. PURVIS, PAS Oklahoma State University, Department of Animal Science, Stillwater, OK 74078
Abstract Fifteen yearling Quarter Horses were used in a split-plot designed experiment to determine the effects of three concentrations of Ca on mineral metabolism, bone density, and parameters of growth. Horses were blocked by sex and BW and randomly assigned to one of three dietary treatments that were formulated to contain 115, 100, and 85% of NRC (10) requirements for Ca. Diets consisted of ground corn, soybean meal, and cottonseed hulls fed at a 70:30 with native prairie grass hay at 2.5% BW. The 25wk trial consisted of three 72-h collection periods at d 0 (Period 1), d 90 (Period 2), and d 180 (Period 3) during which complete urine and fecal collections were taken. Additionally, radiographs of the left front cannon were taken 1 wk prior to each collection for determination of bone density. Data were analyzed with horse and treatment as main effects. Results
from this study demonstrated an increased Ca retention with increased intake during all three periods. There was, however, no radiographic evidence of treatment effect on bone density. (Key Words: Calcium, Bone Density, Growth, Yearling Horses.)
Introduction
Minerals are essential to many functions in the body, ranging from the formation of structural components to enzymatic cofactors and energy transfer. Mineral research has been of great interest to the horse industry, especially with regard to growing horses. Calcium and phosphorus requirements for growing horses were estimated from research performed in ponies (8, 18, 20, 21). Krook and Maylin (9) reported that a nutrient is generally required in inverse proportion to BW. Therefore, the data reported from 200-kg ponies may not be applicable to 500-kg horses when expressed as milligrams of nutrient per kilogram of BW. Consequently, the objective of this experiment was 1Approved for publication by the director, to evaluate the effects of feeding Oklahoma Agriculture Experiment Station. various levels of Ca on mineral 2To whom correspondence should be admetabolism, bone density, and dressed: [email protected] parameters of growth in yearling Quarter Horses.
Materials and Methods Fifteen yearling Quarter Horses were used in a split-plot designed experiment to evaluate the response of Ca metabolism, bone density, and parameters of growth to varying concentrations of dietary Ca. Horses were blocked by sex and BW and then randomly assigned to one of three treatments (high, basal, and low). Horses were fed approximately 2.5% of BW/d in total ration. Experimental diets consisted of corn, soybean meal, and cottonseed hulls fed at 70:30 with prairie grass hay (Table 1). Diets were formulated to contain Ca concentrations at 115% (high; H), 100% (basal; B), and 85% (low; L) of NRC requirements. The 25-wk trial consisted of three 72-h collection periods at d 0 (Period 1; 12 mo of age), d 90 (Period 2; 15 mo of age), and d 180 (period 3; 18 mo of age) during which complete urine and fecal collections were taken. Total urine was collected via urine harnesses. Multiple fecal grab samples were also taken during the 72-h collection period. Grab samples were immediately frozen for later mineral analysis. Daily aliquots of feces and urine were taken to make a composite from which subsequent mineral analyses were performed. Fecal mineral analysis was performed
278
Moffett et al.
Diets H, B, and L. Dry matter digestibility ranged from 58 to 69% across all periods and treatments. During Periods 1 and 2, DMD did not differ Treatment significantly between treatments. However, DMD was less (P<0.05) for Item High Ca Basal Ca Low Ca horses consuming Diet L (58%) than for horses consuming Diets B (67%) Ingredient, % and H (65%) during Period 3. The Ground corn 40.50 40.10 39.50 decreased DMD of horses consuming Soybean meal 14.00 14.20 13.60 Diet L during Period 3 might have Cottonseed hulls 14.60 15.00 16.40 been due to the numerical decrease in a 0.30 0.30 0.30 TM salt DMI and increased FO. Limestone 0.50 0.40 0.20 The DMD values observed in the Dicalcium phosphate 0.10 –– –– present study are greater than those Prairie grass hay 30.00 30.00 30.00 Nutrient reported by others (1, 3) who obDEb, Mcal/kg 2.80 2.81 2.79 served values ranging from 49 to 50% CP, % 15.4 15.1 14.5 and 48 to 52% in yearling and Ca, % 0.48 0.42 0.32 mature horses, respectively. The P, % 0.34 0.31 0.30 difference in the digestibility values may be the result of taking total fecal aTM = Trace mineral. collections in the present study bCalculated from NRC tables. compared with the use of chromic oxide as an external marker in the previous studies. Patterson et al. (16) using Inductively Coupled Plasma DM digestibility (DMD) are shown in demonstrated that calculated values Spectroscopy (ICAP 61®; Spectro Table 2. Urine volume was not (utilizing chromic oxide) for FO are Analysis Instruments, Fitchburg, significantly different across treatgreater when compared with total MA). Urinary Ca and P were anaments for all three periods. During fecal collections. lyzed using a Vitros 250® analyzer Periods 1, 2, and 3 of the trial, no Ca Balance. Data for Ca intake, (Johnson & Johnson Clinical Diagdifference (P>0.05) was detected in excretion, and retention are shown nostics, Inc., Rochester, NY). Weekly DMI and FO for horses consuming in Table 3. Horses consuming Diets H growth parameters were taken during the 25-wk trial, which included BW, withers, hip, hock, shoulder, and TABLE 2. Effects of varying concentrations of Ca on DMI, daily fecal carpus height and heart girth circumoutput (FO), and DM digestibility (DMD)a. ference. Additionally, radiographs Treatment (lateral-medial and dorsal-palmar) of each yearling’s left front thirdPeriod High Ca Basal Ca Low Ca SEMb metacarpal were taken 1 wk prior to each collection period to determine the radiographic bone aluminum 1 equivalence (RBAE). DMI, g/d 5,862.96 6,036.38 6,043.66 323.75 FO, g/d 2,388.84 2,547.76 2,460.06 192.39 Data were analyzed using the DMD, % 59.45 57.74 59.13 2.14 general linear models procedure of 2 SAS (17) with horse and treatment as DMI, g/d 6,849.04 6,938.96 6,580.28 323.75 main effects. Least squares means FO, g/d 2,078.20 2,308.74 2,355.22 192.39 were calculated for each treatment DMD, % 69.38 66.62 64.20 2.14 within a given period, and the p-diff 3 procedure of SAS was used to test for DMI, g/d 7,864.40 8,123.20 7,533.00 323.75 differences between treatment means. FO, g/d 2,698.60 2,660.60 3,104.80 192.39
TABLE 1. Composition of treatment diets (as fed basis).
DMD, %
Results and Discussion DMI, Fecal Output, and DM digestibility. Data for daily DMI, fecal output (FO), urine volume, and
aValues
65.40c
67.20c
58.00d
are least squares means.
bValues are average standard errors. c,dMeans
within a row with different superscripts differ (P<0.05).
2.14
279
CASE STUDY: Calcium Metabolism in Yearling Quarter Horses
TABLE 3. Effects of varying concentrations of Ca on mineral balancea. Treatment High Ca
Basal Ca
Low Ca
SEMb
Intake, g/d Fecal, g/d Urine, g/d Balance, g/d
28.13c 17.13c 2.92 8.07c
25.35c 15.47c 2.97 6.90c
19.33d 11.73d 4.86 2.74d
1.35 1.33 0.65 1.69
Intake, g/d Fecal, g/d Urine, g/d Balance, g/d
32.87c 18.56c 1.45 12.86c
29.14c 17.66c 1.54 9.93cd
21.05d 12.51d 1.04 7.49d
1.35 1.33 0.65 1.69
Intake, g/d Fecal, g/d Urine, g/d Balance, g/d
37.75c 22.25c 3.85 11.64fg
34.12c 17.21d 3.30 13.59f
24.10d 12.82e 4.46 6.82g
1.57 1.33 0.65 2.32
Period 1
2
3
aValues
are least squares means.
bValues are average standard errors. c,d,eMeans f,gMeans
within a row with different superscripts differ (P<0.05). within a row with different superscripts differ (P<0.10).
and B had a significantly greater intake and fecal excretion of Ca than horses fed Diet L during Periods 1 and 2. During Period 3, similar results were observed for Ca intake, but fecal excretion of Ca decreased significantly between the Diets H (22.25 g/ d), B (17.21 g/d), and L (12.82 g/d). Urinary excretion of Ca was not different (P>0.05) between horses consuming Diets H, B, and L during all three periods. During Period 1, retention of Ca was greater (P<0.05) in horses consuming Diets H and B vs Diet L. Furthermore, those horses fed Diet H retained more Ca (P<0.05) than horses fed Diet L during Period 2. During Period 3, there was a tendency (P<0.10) for horses consuming Diet B to have a greater Ca balance than those fed Diet L. Horses consuming Diet H also had a numerically greater retention of Ca than those fed Diet L, although not significant. The increased retention of Ca in horses consuming Diet H during Periods 1 and 2 is similar to previous studies that have shown an en-
hanced Ca balance in horses and ponies consuming supplemental Ca (2, 13, 14, 18, 19). Schryver et al. (18, 19) observed that as Ca intake increased from 29 mg/kg BW on the low diet to 242 mg/kg BW on the high, retention of Ca increased from –7.5 to 56 mg/kg BW, respectively. Bone Density. The effect of varying levels of Ca on bone density of yearling horses is reported in Table 4. The RBAE of the lateral cortex was similar (P>0.05) between treatments for Periods 1 and 3. However, there was a tendency (P<0.10) for horses fed Diet H to have a greater RBAE for the lateral cortex when compared with horses fed Diet B during Period 2. These results were similar to those of Nielsen et al. (13, 14), who reported a tendency for the RBAE of the lateral cortex of 2-yr-old horses to increase in the high group (high Ca, high training level) while the control group (adequate Ca, controlled training level) remained unchanged.
TABLE 4. Effects of varying concentrations of Ca on bone density of yearling horsesa. Treatment Period
High Ca
Basal Ca
Low Ca
SEM b
1 Lateral RBAEc (mm Al) Medial RBAE (mm Al) Dorsal RBAE (mm Al) Palmar RBAE (mm Al) Total RBAE (mm2 Al)
19.40 19.60 19.00 18.40 342.51
21.20 21.60 18.60 18.00 551.82
22.60 22.20 22.40 22.00 530.04
1.87 1.85 1.84 1.82 112.45
Lateral RBAE (mm Al) Medial RBAE (mm Al) Dorsal RBAE (mm Al) Palmar RBAE (mm Al) Total RBAE (mm2 Al)
26.60d 26.60 20.60 19.40 346.09
21.60e 22.40 21.80 21.40 424.07
23.60de 23.80 22.20 21.80 512.75
1.87 1.85 1.84 1.82 112.45
Lateral RBAE (mm Al) Medial RBAE (mm Al) Dorsal RBAE (mm Al) Palmar RBAE (mm Al) Total RBAE (mm2 Al)
24.40 24.00 20.20 19.40 417.47
22.20 21.70 21.60 21.00 389.86
23.80 23.60 22.40 21.60 388.60
1.87 1.85 1.84 1.82 112.45
2
3
aValues
are least squares means.
bValues are average standard errors. cRBAE
= Radiographic bone aluminum equivalence. within a row with different superscripts differ (P<0.10).
d,eMeans
280
Moffett et al.
Savoy, IL.
TABLE 5. Mean response of growth parameters in yearling horses fed varying concentrations of Caa,b. Treatment Growth parameter
High Ca
Basal Ca
Low Ca
SEM c
BW, kg ADG, kg/d Wither height, cm Hip height, cm Shoulder height, cm Hock height, cm Knee height, cm Heart girth, cm
355.42 0.39 137.05 141.47 94.81 51.58 41.16 159.12
371.39 0.40 138.22 143.64 95.24 51.96 41.34 158.55
370.40 0.41 141.17 145.22 96.50 53.54 43.03 160.04
17.68 0.015 1.55 1.66 1.26 0.75 0.77 2.81
aValues
are least squares means.
cValues are average standard errors.
Implications Results from this study demonstrated that Ca balance was not significantly enhanced by supplemental Ca above (115%) NRC recom-
4. Gibbs, P. G., S. H. Sigler, and T. B. Goehring. 1989. Influence of diet on growth and development of yearling horses. J. Equine Vet. Sci. 9(4):215. 5. Hiney, K., G. D. Potter, P. G. Gibbs, and S. M. Bloomfield. 2000. Response of serum biochemical markers of bone metabolism to training in the juvenile racehorse. J. Equine Vet. Sci. 20:851. 6. Hintz, H. F., H. F. Schryver, and J. E. Lowe. 1986. Calcium for pregnant mares and growing horses. Equine Pract. 8:5. 7. Jordan, R. M., V. S. Myers, B. Yoho, and F. Spurrell. 1973. A note on calcium and phosphorus levels fed to ponies during growth and reproduction. In Proc. 3rd Equine Nutr. Res. Symp., Gainesville, FL. p 55. Equine Nutr. Physiol. Soc., Savoy, IL.
bMeans do not differ (P>0.05) between treatments.
The RBAE of the medial, dorsal, and palmar cortices were not different (P>0.05) between treatments during any period. Nielsen et al. (13, 14) observed similar results in 2-yr olds in training in which no difference in RBAE were noted between treatments (high vs control). Concerning total RBAE, there were no significant differences between treatments for all periods. Similar results were reported in 2-yr olds in training in which no significant differences in total RBAE values were observed between treatments (high vs control) (6, 14). Parameters of Growth. Mean values for all variables of growth are shown in Table 5. There were no significant differences between treatment means for BW, withers, hip, hock, shoulder, and carpus height and heart girth circumference for the 25-wk trial. These results are similar to work performed by Gibbs et al. (5) who varied protein, Ca, and P levels and observed no significant difference in ADG, heart girth circumference, and wither height for yearlings.
3. Cooper, S. R., D. R. Topliff, D. W. Freeman, J. E. Breazile, and R. D. Geisert. 2000. Effects of dietary cation-anion difference in weanling horses. J. Equine Vet. Sci. 20:30.
mended levels. Conversely, when horses were fed low (85% of NRC) Ca diets, the retention of Ca was significantly reduced. Despite this decreased Ca balance, no significant differences were detected between treatments in bone density or skeletal growth parameters. These data therefore support the current NRC recommendations for Ca intake in yearling horses and suggest that feeding Ca in excess of these recommended levels may not be of benefit to skeletal growth and mineralization in yearling horses.
Literature Cited 1. Baker, L. A., D. R. Topliff, D. W. Freeman, R. G. Teeter, and B. Stoecker. 1998. The comparison of two forms of sodium in the dietary cation-anion difference equation: Effects on mieral balance in sedentary horses. J. Equine Vet. Sci. 18:389. 2. Buchholz, M. A., L. A. Baker, J. L. Pipkin, M. J. Mansell, L. W. Greene, J. C. Haliburton, and R. C. Bachman. 1999. The effect of calcium and phosphorus supplementation, inactivity and subsequent aerobic training on mineral balance of varying ages of horses. In Proc. 16th Equnie Nutr. Physiol. Symp., Raleigh, NC. p 12. Equine Nutr. Physiol. Soc.,
8. Krook, L., and G. A. Maylin. 1988. Fractures in Thoroughbred race horses. Cornell Vet. 98:1. 9. National Academy of Science. 1989. Nutrient Requirements of Horses. (5th Ed.). National Research Council, Washington, D.C. 10. Nielsen, B. D. 1992. Training distance to failure and density of the third metacarpal in young racing Quarter Horses fed sodium zeolite A. M.S. Thesis. Texas A&M Univ., College Station, Texas. 11. Nielsen, B. D., G. D. Potter, E. L. Morris, T. W. Odom, D. M. Senor, J. A. Reynolds, W. B. Smith, and M. T. Martin. 1997. Changes in the third metacarpal and frequency of bone injuries in young Quarter Horses during race training-observations and theoretical considerations. J. Equine Vet. Sci. 17:541. 12. Nielsen, B. D., G. D. Potter, L. W. Greene, E. L. Morris, M. Murray-Gerzik, W. B. Smith, and M. T. Martin. 1998. Characterization of changes related to mineral balance and bone metabolism in the young racing Quarter Horse. J. Equine Vet. Sci. 18:190. 13. Nielsen, B. D., G. D. Potter, L. W. Greene, E. L. Morris, M. Murray-Gerzik, W. B. Smith, and M. T. Martin. 1998. Response of yearling horses in training to varying concentrations of dietary calcium and phosphorus. J. Equine Vet. Sci. 18:397. 14. Patterson, D. P., S. R. Cooper, D. W. Freeman, and R. G. Teeter. 2001. Estimation of fecal output and dry matter digestibility using various chromic oxide marker methods in the horse. In Proc. 17th Equine Nutr. Physiol. Symp., Lexington, KY. p 402. Equine Nutr. Physiol. Soc., Savoy, IL. 15. SAS. 1999. SAS User’s Guide: Statistics. SAS Institute Inc., Cary, NC. 16. Schryver, H. F., P. H. Craig, and H. F. Hintz. 1970. Calcium metabolism in ponies fed varying levels of calcium. J. Nutr. 100:955.
CASE STUDY: Calcium Metabolism in Yearling Quarter Horses
17. Schryver, H. F., P. H. Craig, H. F. Hintz, D. E. Hogue, and J. E. Lowe. 1970. The site of calcium absorption in the horse. J. Nutr. 100:1127. 18. Schryver, H. F., H. F. Hintz, and P. H. Craig. 1971. Calcium metabolism in ponies
fed a high phosphorus diet. J. Nutr. 101:259. 19. Schryver, H. F., H. F. Hintz, and P. H. Craig. 1971. Phosphorus metabolism in ponies fed varying levels of phosphorus. J. Nutr. 101:1257.
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20. Schryver, H. F., H. F. Hintz, and J. E. Lowe. 1978. Calcium metabolism, body composition and sweat losses of exercised horses. Am. J. Vet. Res. 39:245.