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A Comparison of Actual and Recommended Digestible Energy Intakes Derived from Differing Feeding Standards for Miniature Horses
Abstracts Vol 29, No 5 (2009)
482
Keywords: Glycogen; Exercise; Reining horse REFERENCES 1. Rammerstorfer C, Potter GD, Cudd TA, Gibbs PG, Farner, DD, Householder DD. Physiological responses of mature Quarter Horses to reining training when fed conventional and fat-supplemented diets. J. Equine Vet. Sci. 1997;18(3):175-183. 2. Lacombe VA, Hinchcliff KW, Geor RJ, Baskin CR. Muscle glycogen depletion and subsequent replenishment affect anaerobic capacity of horses. J. Applied Physiol. 2001;91(4):1782-1790. 3. Kronfeld JS. Glycemic index, insulin signaling, exercise, and EGAD. J. Equine Vet. Sci. 2005;25(11):484-487. 4. McCutcheon LJ, Byrd SK, Hodgson DR. Ultrastructural alterations in equine skeletal muscle associated with fatiguing exercise. In Equine Exercise Physiology, Person SGB, Lindholm A, Jeffcott LB (Eds.), 3. Davis, CA: ICEEP Publications, 1991, pp. 269.
ACKNOWLEDGEMENTS Cargill Animal Nutrition
31547 A Comparison of Actual and Recommended Digestible Energy Intakes Derived from Differing Feeding Standards for Miniature Horses A.L. Scherer-Hoock,*1 E.A. Greene,1 M. Lennox,2 and C. Brown-Douglas2, 1University of Vermont, Burlington, VT, USA, 2Kentucky Equine Research, Versailles, KY, USA
INTRODUCTION Studies agree that smaller equines digest energy more efficiently than average sized horses.1,2 This is one reason that small equines like ponies and miniature horses may not be the best model of nutrition for larger horses,3 nor may larger horses be an adequate model for smaller equines. Feed intake quantity is largely based on a horse’s weight. However, feed manufacturers generally supply feeding recommendations for horses 360 kg and over, when the average miniature horse weighs around 100 kg.4 Anecdotal observations of obesity in miniature horses could in part be due to improper feeding recommendations (i.e. overfeeding) for such small equines. Proper feeding recommendations are crucial for preventing obesity, which has been linked to various metabolic conditions.5 The purpose of this study was to determine if feeding recommendations could be linearly scaled down to accurately reflect the digestible energy (DE) intake required by miniature horses maintaining a healthy weight and body condition score (BCS).6
MATERIALS AND METHODS Twelve mature miniature horses participating in a local American Miniature Horse Association (AMHA) show were selected as the reference group because they closely portrayed the ideal condition of a miniature horse as described by the AMHA.7 Horses varied in gender, ranging in age from 4-13 years, weighing from 96-123 kg, and ranging in BCS from 4-6. A single researcher recorded each horse’s BCS, body weight, and weight of daily intake of hay and grain on the day of the trial. Owners provided information on the horse’s workload, behavior, turnout, and health history. Only healthy horses whose weight and feed intake had stayed constant for at least six months prior to this study were used in the reference group. Using an equation developed by Kentucky Equine Research,8 DE in each horse’s diet was calculated from the feed manufacturers’ guaranteed analysis. Actual DE intake of each horse was determined from this calculation and their recorded feed intake. This reference group portrays how much DE healthy miniature horses with an appropriate weight and BCS actually consume per day. The mean DE intake of the reference group was compared to DE requirements (sum of hay and grain) suggested in several other feeding standards that were linearly scaled down to fit the weight of each horse in the reference group. In detail these standards are: (1) the equation for horses less than 600 kg (adjusted for workload) from the NRC Nutrient Requirements of Horses 5th edition,9 (2) equations 1.7a and 1.7b of the NRC Nutrient Requirements of Horses 6th edition,10 (3) the mean DE intake of manufacturer’s recommendations for feeds appearing in the study, (4) PurinaÒ0 s feeding recommendations specifically for miniature horses, and (5) the recommendations for PlatformÒ Miniature Horse and Pony Feed. Each horse’s DE intake was compared to the appropriate recommendations for their workload and gender within each requirement standard. Hotelling0 s T2 statistic (a multivariate extension of the paired t-test) was calculated11 in order to see if there was a significant difference between the mean DE of all diets. Table 1. Mean digestible energy of actual and recommended diets for miniature horses Group
Mean DE (mcal/day)
Standard error P within group value*
Reference NRC ’89 NRC ’07 Manufacturers PurinaÒ** PlatformÒ**
3.59 5.77 4.57 5.77 4.81 5.54
0.245 0.160 0.157 0.282 0.155 0.332
0.001 0.007 0.001 0.001 0.002
* when compared to actual DE intake ** recommendations formulated specifically for miniature horses retrieved from manufacturer’s website
Abstracts Vol 29, No 5 (2009)
This was followed by a paired-samples t-test comparing the mean DE intake of the reference group to the mean DE intake recommendations of each standard.
RESULTS AND DISCUSSION A significant difference (P < 0.001) between the means of all groups was found. A significant difference (P < 0.007) between the reference group and all feeding standards was also observed (Table 1). These data show that each feeding standard recommended a significantly higher DE intake than the reference group actually consumed. This suggests that the currently published sources of feeding recommendations evaluated here, when linearly scaled down, overestimate the DE that miniature horses need to consume in order to maintain an acceptable body weight. These findings are inconsistent with the results of Pagan and Hintz in 1986.12 Though the sample size of this study was limited, the degree of significance observed shows that further study is warranted. Future studies may use a larger sample size in order to see if the same results are found. Additional research would hopefully lead to the computation of new miniature horse-specific feeding recommendations that would provide a better foundation for formulating rations for small equines, thereby lessening the instance of overfeeding and its negative impacts. Keywords: Miniature horse; Digestible energy; Intake REFERENCES 1. Slade LM, Hintz HF. Comparison of digestion in horses, ponies, rabbits and guinea pigs. J Anim. Sci. 1969;28:842. 2. Barth KM, Williams JW, Brown DG. Digestible energy requirements of working and non-working ponies. J Anim. Sci. 1977;44:585-589. 3. Robie SM, Janson, CH, et al. Equine serum lipids and glucose in Morgan and Thoroughbred horses in Shetland ponies. Am. J. Vet. Res 1975;36:1705-1708 4. Kennedy MA, Hoekstra KE. Field method for determining the weight of the miniature horse. World equine veterinary review 1998;3:14-18. 5. Frank N, Elliott SB, et al. Physical characteristics, blood hormone concentrations, and plasma lipid concentrations in obese horses with insulin resistance. 2006;228:1383-1390. 6. Henneke DR, Potter GD, et al. Relationship between condition score, physical measurement and body fat percentage in mares. Equine Vet. J. 1983;15:371-372. 7. AMHA. About the breed. 1996-2007. 8. Pagan JD. Measuring the Digestible Energy Content of Horse Feeds. Advances in Equine Nutrition I 1998;71-76. 9. NRC. The Nutrient Requirements of Horses, 5th rev. edn., Washington, DC: Natl. Acad. Press, 1989. 10. NRC. The Nutrient Requirements of Horses, 6th rev. edn., Washington, DC: Natl. Academic Press, 2007. 11. (1989-2007) SPSS Inc., 16.0.2 edn. 12. Pagan JD, Hintz HF. Equine Energetics I. Relationship between Body Weight and Energy Requirements in Horses. J. Anim. Sci. 1986;63:815-821.
483
ACKNOWLEDGEMENTS The authors would like to thank Joe Pagan, Alan Howard, Josie Davis, and Lyndon Carew for their assistance with this research project.
31889 Comparison of Biochemical Values between Miniature and Full Size Horses Fed a Marine or Animal Fat Diet B. Dominguez,*1 S.R. Furtney,1 M.J. Arns,2 T.S. Epp,3 and J.S. Pendergraft1, 1Sul Ross State University, Alpine, TX, USA, 2University of Arizona, Tucson, AZ, USA, 3JBS, United, Sheridan, IN, USA
INTRODUCTION The most common fats fed in horse diets are corn oil, and soybean oil which have a relatively high percentage of PUFA. The National Research Council1 recommends that the dietary dry matter include at least 0.5% linoleic acid (LA). Linoleic acid is the main source of omega-6 fatty acid whereas alpha-linolenic acid (ALA) is the major omega-3 fatty acid. Both are metabolized further and used in the synthesis of eicosanoids. Eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA) are omega-3 fatty acids that have proven to have many beneficial effects in animals and humans.2–4 Essential fatty acid nutrition in the horse is of great interest due to its clinical relevance, and the lack of research in this area offers great scope for future investigations. However, the relationship between eicosanoids and their essential fatty acid precursors is complex and requires thorough investigation before dietary recommendations can realistically be made. Therefore, the objective of this study was to evaluate dietary n-3 and n-6 supplementation on 15 blood chemistry profiles in miniature and Quarter Horse mares.
MATERIALS AND METHODS Ten Quarter Horse (QH) mares, 3 to 15 yr of age (435 37 kg) and 10 miniature horse (M) mares, 7 to 19 yr of age (102 17 kg) were used in a 2 x 2 factorial design to compare biochemical values between miniature horses and full size horses. Five miniature horses and five full size horses were blocked within breed by age and initial body weight and assigned to either an n-3 PUFA (MF; n ¼ 10) supplemented concentrate or an n-6 animal fat (AF; n ¼ 10) supplemented concentrate. The basal diet included coastal bermuda hay provided at 1.18 kg/100 kg BW. The n-3 PUFA was a marine-derived source (JBS United) and was designed to deliver EPA and DHA at a combined concentration of 64.4 mg/kg BW/d. The diets were isocaloric and fed in a 30:70 concentrate:hay
482
Keywords: Glycogen; Exercise; Reining horse REFERENCES 1. Rammerstorfer C, Potter GD, Cudd TA, Gibbs PG, Farner, DD, Householder DD. Physiological responses of mature Quarter Horses to reining training when fed conventional and fat-supplemented diets. J. Equine Vet. Sci. 1997;18(3):175-183. 2. Lacombe VA, Hinchcliff KW, Geor RJ, Baskin CR. Muscle glycogen depletion and subsequent replenishment affect anaerobic capacity of horses. J. Applied Physiol. 2001;91(4):1782-1790. 3. Kronfeld JS. Glycemic index, insulin signaling, exercise, and EGAD. J. Equine Vet. Sci. 2005;25(11):484-487. 4. McCutcheon LJ, Byrd SK, Hodgson DR. Ultrastructural alterations in equine skeletal muscle associated with fatiguing exercise. In Equine Exercise Physiology, Person SGB, Lindholm A, Jeffcott LB (Eds.), 3. Davis, CA: ICEEP Publications, 1991, pp. 269.
ACKNOWLEDGEMENTS Cargill Animal Nutrition
31547 A Comparison of Actual and Recommended Digestible Energy Intakes Derived from Differing Feeding Standards for Miniature Horses A.L. Scherer-Hoock,*1 E.A. Greene,1 M. Lennox,2 and C. Brown-Douglas2, 1University of Vermont, Burlington, VT, USA, 2Kentucky Equine Research, Versailles, KY, USA
INTRODUCTION Studies agree that smaller equines digest energy more efficiently than average sized horses.1,2 This is one reason that small equines like ponies and miniature horses may not be the best model of nutrition for larger horses,3 nor may larger horses be an adequate model for smaller equines. Feed intake quantity is largely based on a horse’s weight. However, feed manufacturers generally supply feeding recommendations for horses 360 kg and over, when the average miniature horse weighs around 100 kg.4 Anecdotal observations of obesity in miniature horses could in part be due to improper feeding recommendations (i.e. overfeeding) for such small equines. Proper feeding recommendations are crucial for preventing obesity, which has been linked to various metabolic conditions.5 The purpose of this study was to determine if feeding recommendations could be linearly scaled down to accurately reflect the digestible energy (DE) intake required by miniature horses maintaining a healthy weight and body condition score (BCS).6
MATERIALS AND METHODS Twelve mature miniature horses participating in a local American Miniature Horse Association (AMHA) show were selected as the reference group because they closely portrayed the ideal condition of a miniature horse as described by the AMHA.7 Horses varied in gender, ranging in age from 4-13 years, weighing from 96-123 kg, and ranging in BCS from 4-6. A single researcher recorded each horse’s BCS, body weight, and weight of daily intake of hay and grain on the day of the trial. Owners provided information on the horse’s workload, behavior, turnout, and health history. Only healthy horses whose weight and feed intake had stayed constant for at least six months prior to this study were used in the reference group. Using an equation developed by Kentucky Equine Research,8 DE in each horse’s diet was calculated from the feed manufacturers’ guaranteed analysis. Actual DE intake of each horse was determined from this calculation and their recorded feed intake. This reference group portrays how much DE healthy miniature horses with an appropriate weight and BCS actually consume per day. The mean DE intake of the reference group was compared to DE requirements (sum of hay and grain) suggested in several other feeding standards that were linearly scaled down to fit the weight of each horse in the reference group. In detail these standards are: (1) the equation for horses less than 600 kg (adjusted for workload) from the NRC Nutrient Requirements of Horses 5th edition,9 (2) equations 1.7a and 1.7b of the NRC Nutrient Requirements of Horses 6th edition,10 (3) the mean DE intake of manufacturer’s recommendations for feeds appearing in the study, (4) PurinaÒ0 s feeding recommendations specifically for miniature horses, and (5) the recommendations for PlatformÒ Miniature Horse and Pony Feed. Each horse’s DE intake was compared to the appropriate recommendations for their workload and gender within each requirement standard. Hotelling0 s T2 statistic (a multivariate extension of the paired t-test) was calculated11 in order to see if there was a significant difference between the mean DE of all diets. Table 1. Mean digestible energy of actual and recommended diets for miniature horses Group
Mean DE (mcal/day)
Standard error P within group value*
Reference NRC ’89 NRC ’07 Manufacturers PurinaÒ** PlatformÒ**
3.59 5.77 4.57 5.77 4.81 5.54
0.245 0.160 0.157 0.282 0.155 0.332
0.001 0.007 0.001 0.001 0.002
* when compared to actual DE intake ** recommendations formulated specifically for miniature horses retrieved from manufacturer’s website
Abstracts Vol 29, No 5 (2009)
This was followed by a paired-samples t-test comparing the mean DE intake of the reference group to the mean DE intake recommendations of each standard.
RESULTS AND DISCUSSION A significant difference (P < 0.001) between the means of all groups was found. A significant difference (P < 0.007) between the reference group and all feeding standards was also observed (Table 1). These data show that each feeding standard recommended a significantly higher DE intake than the reference group actually consumed. This suggests that the currently published sources of feeding recommendations evaluated here, when linearly scaled down, overestimate the DE that miniature horses need to consume in order to maintain an acceptable body weight. These findings are inconsistent with the results of Pagan and Hintz in 1986.12 Though the sample size of this study was limited, the degree of significance observed shows that further study is warranted. Future studies may use a larger sample size in order to see if the same results are found. Additional research would hopefully lead to the computation of new miniature horse-specific feeding recommendations that would provide a better foundation for formulating rations for small equines, thereby lessening the instance of overfeeding and its negative impacts. Keywords: Miniature horse; Digestible energy; Intake REFERENCES 1. Slade LM, Hintz HF. Comparison of digestion in horses, ponies, rabbits and guinea pigs. J Anim. Sci. 1969;28:842. 2. Barth KM, Williams JW, Brown DG. Digestible energy requirements of working and non-working ponies. J Anim. Sci. 1977;44:585-589. 3. Robie SM, Janson, CH, et al. Equine serum lipids and glucose in Morgan and Thoroughbred horses in Shetland ponies. Am. J. Vet. Res 1975;36:1705-1708 4. Kennedy MA, Hoekstra KE. Field method for determining the weight of the miniature horse. World equine veterinary review 1998;3:14-18. 5. Frank N, Elliott SB, et al. Physical characteristics, blood hormone concentrations, and plasma lipid concentrations in obese horses with insulin resistance. 2006;228:1383-1390. 6. Henneke DR, Potter GD, et al. Relationship between condition score, physical measurement and body fat percentage in mares. Equine Vet. J. 1983;15:371-372. 7. AMHA. About the breed. 1996-2007. 8. Pagan JD. Measuring the Digestible Energy Content of Horse Feeds. Advances in Equine Nutrition I 1998;71-76. 9. NRC. The Nutrient Requirements of Horses, 5th rev. edn., Washington, DC: Natl. Acad. Press, 1989. 10. NRC. The Nutrient Requirements of Horses, 6th rev. edn., Washington, DC: Natl. Academic Press, 2007. 11. (1989-2007) SPSS Inc., 16.0.2 edn. 12. Pagan JD, Hintz HF. Equine Energetics I. Relationship between Body Weight and Energy Requirements in Horses. J. Anim. Sci. 1986;63:815-821.
483
ACKNOWLEDGEMENTS The authors would like to thank Joe Pagan, Alan Howard, Josie Davis, and Lyndon Carew for their assistance with this research project.
31889 Comparison of Biochemical Values between Miniature and Full Size Horses Fed a Marine or Animal Fat Diet B. Dominguez,*1 S.R. Furtney,1 M.J. Arns,2 T.S. Epp,3 and J.S. Pendergraft1, 1Sul Ross State University, Alpine, TX, USA, 2University of Arizona, Tucson, AZ, USA, 3JBS, United, Sheridan, IN, USA
INTRODUCTION The most common fats fed in horse diets are corn oil, and soybean oil which have a relatively high percentage of PUFA. The National Research Council1 recommends that the dietary dry matter include at least 0.5% linoleic acid (LA). Linoleic acid is the main source of omega-6 fatty acid whereas alpha-linolenic acid (ALA) is the major omega-3 fatty acid. Both are metabolized further and used in the synthesis of eicosanoids. Eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA) are omega-3 fatty acids that have proven to have many beneficial effects in animals and humans.2–4 Essential fatty acid nutrition in the horse is of great interest due to its clinical relevance, and the lack of research in this area offers great scope for future investigations. However, the relationship between eicosanoids and their essential fatty acid precursors is complex and requires thorough investigation before dietary recommendations can realistically be made. Therefore, the objective of this study was to evaluate dietary n-3 and n-6 supplementation on 15 blood chemistry profiles in miniature and Quarter Horse mares.
MATERIALS AND METHODS Ten Quarter Horse (QH) mares, 3 to 15 yr of age (435 37 kg) and 10 miniature horse (M) mares, 7 to 19 yr of age (102 17 kg) were used in a 2 x 2 factorial design to compare biochemical values between miniature horses and full size horses. Five miniature horses and five full size horses were blocked within breed by age and initial body weight and assigned to either an n-3 PUFA (MF; n ¼ 10) supplemented concentrate or an n-6 animal fat (AF; n ¼ 10) supplemented concentrate. The basal diet included coastal bermuda hay provided at 1.18 kg/100 kg BW. The n-3 PUFA was a marine-derived source (JBS United) and was designed to deliver EPA and DHA at a combined concentration of 64.4 mg/kg BW/d. The diets were isocaloric and fed in a 30:70 concentrate:hay