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Thirteenth Equine nutrition and physiology symposium
17 .
The Equine Nutrition and Physiology Society (ENPS) held their 13th symposium January 21-23, 1993, in Gamesville, Florida. It was one of their most successful meetings ever, with over 250 people in attendance. Dr. Laurie Lawrence, University of Kentucky, was installed as the 1993-94 president. The Society business address is 309 W. Clark St. Champaign, IL 61820-4605; (217) 346-3182. This year the Society gave 5 members the Fellow Award, which recognizes distinguished service to the horse industry and to ENPS over a long period (> 10 years) of time. Those receiving the award were as follows: Dr. Waco W. Albert who was active in ENPS for many years prior to his death in 1981. He taught at the University of Illinois. Dr. John P. Baker has been actively involved in ENPS since its first meeting in 1968. He served as president of the organization fzom 1979 to 1981. He has been actively involved in the NRC, with the Nutrient Requirements of Horses series since 1978. Dr. Robert M. Jordan was also a charter member of ENPS. He has served on the NRC Nutrient Requirement Subcommittees for both sheep and horses. Dr. Thomas N. Meacham recently retired from the faculty of Virginia Polytechnic Institute and State University, where he developed outstanding courses in horse production and management. Dr. Howard D. Stowe was instrumental in the founding of ENPS, and has been a leader in equine nutrition research
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At each symposium, the ENPS invites internationally known researchers in various disciplines of equine nutrition and physiology, including reproduction, to speak. The special "invited" speakers this year were: Gary Carpenter, Executive Director of the American Association of Equine Practitioners; Gary Carlson, University of California, Davis; O. J. Ginther, University of Wisconsin; and Gerdt Bruin, Research Foundation for Cattle, Sheep and Horses, Lelystat, Holland. The Effect of Exercise on the Incidence of Osteochondrosls In Young Horses Dr. Gerdt Bruin is head of the horse section of a Dutch governmentalresearch department which is endeavoring to institute modern scientific equine management and nutritionprograms among horse breeders in Holland. Because the sale of Dutch Warmblood Horses is important in Holland, Bruin's work utilized young Dutch Warmbloods. He described his researchwithmorethan 100younghorses. Bruin described the two areas of management in which he was involved as feeding and exercise. He has concentrated on a program over the last 10 years with the goal of reducing the incidence of osteochondrosis, or as it is often called "developmentalorthopedicdisease(DOD)." Since European horses, in general, have an approximate incidence of 20% osteochondrosis, according to Bruin, it was important to discover some means of reducing the incidence. He tried two approaches: nutrition and exercise management.
suit, Bruin now recommends to Dutch breeders that they feed a high level of energy to their young horses. For the past few years he has fed all the young horses in his program a large amount of concentrate with no ill effects. He emphasized that the diet must be properly balanced with adequate minerals and vitamins. Since Brain's early studies in nutritional manipulations made no difference in the incidence of osteochondrosis, he concentrated on exercise management. He conducted many trial with various levels of exercise provided for young horses. Some beginning at weaning-which was done at 3 months of age. Bruin studied reports of bene physiology and growth, and knew that very few cycles (strides) were required as a stimulus for bone to remodel. He reasoned that most of the damage was done during exercise because of fatigue from exercise being too long. It seemed to him that the intensity of exercise should be great and the duration short. Therefore, he began to force his young horses into ~t very short sprint on a very hard surface at regular intervals. In one experiment, he divided a group of young horses into two exercise groups. One group was forced to sprint 3 times per week, and then twice a week exercise at a walk and trot (much like horses receive in the U.S. on a hot walker). The other group received only the walk and trot exercise 5 times per week. This exercise began for both groups a 3 months of age and continued to 24 months of age. All the horses were kept on a very high level of feeding.
JOURNAL OF EQUINEVETERINARYSCIENCE
Bruin had built a cement area for the sprint work, on which he put an inch, or so, of sand. The horses were not lounged, but were forced to sprint over the hard surface at up to 6 meters per second for a short distance. This was repeated a number of times during a single exercise bout. The number of times the horse was sprinted in a single session depended on the horse; it's age, condition, temperament, etc. Over the 21 month training period the high exercise group traveled an average of 240 kilometers at a sprint. The low exercise group averaged only about 180 kilometers at a trot. They began to ride the horses when they were long yeartings. By the time they were 2 1/2 years old, the horses were being ridden in 3-day eventing. Throughout the 21 month study, Bruin compared horses in the two groups. There was no difference in wither height between the two groups, but all of Bruin's horses were larger than typical farm raised horses at the same age. They grew faster, but eventually the farm raised horses caught up with them. There were no differences among the two groups of Bruin's horses in lengthand circumference of the cannon bones. The most startling difference in the two groups was the ihcidence of osteochondrosis. The low exercise group had an incidence similar to the general popul a t i o n - about 20%. The high exercise group had only about 6% osteochondrosis. Most osteochodrosis (DOD) seen in these horses, according to Bruin, was in the knees and tarsal joints. Horses were not necropsied nor radiographed on a systematic basis. Osteochondrosis was not considered unless a horse showed lameness. When asked how the Dutch breeders accepted his radical approach to management of young horses, Bruin said they all thought he was crazy. The breeders said he fed too much, he weaned too early, and he was foolish to exercise on cement. Factors In Training Bruin cited 5 factors important in the
Volume 13, Number 3, 1993
training program of young horses. The first is character. Young horses need social contact. They need to relate to other horses and also to the trainer. The type of housing-- box stall versus paddock with others-- is important to development of character, according to Bruin. The trainer needs to do everything possible to encourage a willingness to perform to the maximum. The second factoris strength ofl~one. This was the purpose of Bruin's high intensity exercise program with a short duration and hard surface. He cautioned against endurance type training, or "long, slow distance." He recommended sprints for 10-15 seconds only, several times in a workout for a maximum of 10 to 15 minutes. Bruin said that injuries are a result of incorrect training. The third factor is coordination. Coordination is learned, to a large degree. The young horse needs the opportunity to play in a paddock with other young horses. If this is not possible, exercise must be provided where the horse can move at all different paces for a short duration, with quick turns and stops. The fourth factor is muscle strength. This strength comes with relatively tittle exercise and over a short period of time. Walking exercise helps develop this muscular strength. Bruin advocates daily draught pulling for horses in the later stages of training. He believes this is good for developing muscle strength. It can be over done, however, and Bruin admonished that a trainer must be "specific"in trainingw the exercise provided should be as close to the work performed, or eventual performance, as possible. The fifth factor is metabolic capacity. The first 15% of improvement comes easy, according to Bruin. Continual work can usually bring 50% improvement in metabolic capacity. Exercise bouts for improvement of metabolic capadty should be provided 2-3 times per week over a 3 month period. This should consist of 3-6 works at about 3 minutes each at 85% maximum heart rate on a treadmill, or uphill. This would be at a heart rate of about 200 for the typical horse.
RESEARCH INVOLVING HIGH INTENSITY EXERCISE As a special guest lecturer at the ENPS Symposium, Dr. Gary Carlson, firm the University of California, Davis, spoke on the topic "Acid:buse and electrolyte alterations associated with maximal exercise." He began his discussion, however, with comments on the problems in research involving high intensity exercise. He cautioned that results from so-called maximal intensity exercise needs to be carefully evaluated because often there are significant incorrect assumptions made in interpretation of the results. The first problem he mentioned was one of timing in relation to exercisecFor example, blood collected within a~few minutes of the end of exercise is often reported as flit were exactly at the peak of exercise, when in fact, many of the parameters measured beg)m to C~ange immediately post exercise. Thus t~e data are incorrect to the extent that the parameter measured changes after exercise. Another problem is that often data are compared between parameter of blood collected either venous or arterial. Carlson maintained that there are often important differences. Also the site of collection can introduce differences in data. As an example, he pointed out that when arterial blood is taken, a declining pH is found with exercise, and a bicarbonate increase; when a venous blood sample is taken there is no bicarbonate change and acidosis is found. It is important to consider the core body temperature of the horse at the time of collection of samples. Temperature corrections are necessary for some parameters-- blood gas data being an example. The assumptions made about the various changes in physiological parameters during exercise influence the calculations made. Researchers, and those who interpret the results need to keep this in mind, according to Carlson.
135
The Equine Nutrition and Physiology Society (ENPS) held their 13th symposium January 21-23, 1993, in Gamesville, Florida. It was one of their most successful meetings ever, with over 250 people in attendance. Dr. Laurie Lawrence, University of Kentucky, was installed as the 1993-94 president. The Society business address is 309 W. Clark St. Champaign, IL 61820-4605; (217) 346-3182. This year the Society gave 5 members the Fellow Award, which recognizes distinguished service to the horse industry and to ENPS over a long period (> 10 years) of time. Those receiving the award were as follows: Dr. Waco W. Albert who was active in ENPS for many years prior to his death in 1981. He taught at the University of Illinois. Dr. John P. Baker has been actively involved in ENPS since its first meeting in 1968. He served as president of the organization fzom 1979 to 1981. He has been actively involved in the NRC, with the Nutrient Requirements of Horses series since 1978. Dr. Robert M. Jordan was also a charter member of ENPS. He has served on the NRC Nutrient Requirement Subcommittees for both sheep and horses. Dr. Thomas N. Meacham recently retired from the faculty of Virginia Polytechnic Institute and State University, where he developed outstanding courses in horse production and management. Dr. Howard D. Stowe was instrumental in the founding of ENPS, and has been a leader in equine nutrition research
134
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
At each symposium, the ENPS invites internationally known researchers in various disciplines of equine nutrition and physiology, including reproduction, to speak. The special "invited" speakers this year were: Gary Carpenter, Executive Director of the American Association of Equine Practitioners; Gary Carlson, University of California, Davis; O. J. Ginther, University of Wisconsin; and Gerdt Bruin, Research Foundation for Cattle, Sheep and Horses, Lelystat, Holland. The Effect of Exercise on the Incidence of Osteochondrosls In Young Horses Dr. Gerdt Bruin is head of the horse section of a Dutch governmentalresearch department which is endeavoring to institute modern scientific equine management and nutritionprograms among horse breeders in Holland. Because the sale of Dutch Warmblood Horses is important in Holland, Bruin's work utilized young Dutch Warmbloods. He described his researchwithmorethan 100younghorses. Bruin described the two areas of management in which he was involved as feeding and exercise. He has concentrated on a program over the last 10 years with the goal of reducing the incidence of osteochondrosis, or as it is often called "developmentalorthopedicdisease(DOD)." Since European horses, in general, have an approximate incidence of 20% osteochondrosis, according to Bruin, it was important to discover some means of reducing the incidence. He tried two approaches: nutrition and exercise management.
suit, Bruin now recommends to Dutch breeders that they feed a high level of energy to their young horses. For the past few years he has fed all the young horses in his program a large amount of concentrate with no ill effects. He emphasized that the diet must be properly balanced with adequate minerals and vitamins. Since Brain's early studies in nutritional manipulations made no difference in the incidence of osteochondrosis, he concentrated on exercise management. He conducted many trial with various levels of exercise provided for young horses. Some beginning at weaning-which was done at 3 months of age. Bruin studied reports of bene physiology and growth, and knew that very few cycles (strides) were required as a stimulus for bone to remodel. He reasoned that most of the damage was done during exercise because of fatigue from exercise being too long. It seemed to him that the intensity of exercise should be great and the duration short. Therefore, he began to force his young horses into ~t very short sprint on a very hard surface at regular intervals. In one experiment, he divided a group of young horses into two exercise groups. One group was forced to sprint 3 times per week, and then twice a week exercise at a walk and trot (much like horses receive in the U.S. on a hot walker). The other group received only the walk and trot exercise 5 times per week. This exercise began for both groups a 3 months of age and continued to 24 months of age. All the horses were kept on a very high level of feeding.
JOURNAL OF EQUINEVETERINARYSCIENCE
Bruin had built a cement area for the sprint work, on which he put an inch, or so, of sand. The horses were not lounged, but were forced to sprint over the hard surface at up to 6 meters per second for a short distance. This was repeated a number of times during a single exercise bout. The number of times the horse was sprinted in a single session depended on the horse; it's age, condition, temperament, etc. Over the 21 month training period the high exercise group traveled an average of 240 kilometers at a sprint. The low exercise group averaged only about 180 kilometers at a trot. They began to ride the horses when they were long yeartings. By the time they were 2 1/2 years old, the horses were being ridden in 3-day eventing. Throughout the 21 month study, Bruin compared horses in the two groups. There was no difference in wither height between the two groups, but all of Bruin's horses were larger than typical farm raised horses at the same age. They grew faster, but eventually the farm raised horses caught up with them. There were no differences among the two groups of Bruin's horses in lengthand circumference of the cannon bones. The most startling difference in the two groups was the ihcidence of osteochondrosis. The low exercise group had an incidence similar to the general popul a t i o n - about 20%. The high exercise group had only about 6% osteochondrosis. Most osteochodrosis (DOD) seen in these horses, according to Bruin, was in the knees and tarsal joints. Horses were not necropsied nor radiographed on a systematic basis. Osteochondrosis was not considered unless a horse showed lameness. When asked how the Dutch breeders accepted his radical approach to management of young horses, Bruin said they all thought he was crazy. The breeders said he fed too much, he weaned too early, and he was foolish to exercise on cement. Factors In Training Bruin cited 5 factors important in the
Volume 13, Number 3, 1993
training program of young horses. The first is character. Young horses need social contact. They need to relate to other horses and also to the trainer. The type of housing-- box stall versus paddock with others-- is important to development of character, according to Bruin. The trainer needs to do everything possible to encourage a willingness to perform to the maximum. The second factoris strength ofl~one. This was the purpose of Bruin's high intensity exercise program with a short duration and hard surface. He cautioned against endurance type training, or "long, slow distance." He recommended sprints for 10-15 seconds only, several times in a workout for a maximum of 10 to 15 minutes. Bruin said that injuries are a result of incorrect training. The third factor is coordination. Coordination is learned, to a large degree. The young horse needs the opportunity to play in a paddock with other young horses. If this is not possible, exercise must be provided where the horse can move at all different paces for a short duration, with quick turns and stops. The fourth factor is muscle strength. This strength comes with relatively tittle exercise and over a short period of time. Walking exercise helps develop this muscular strength. Bruin advocates daily draught pulling for horses in the later stages of training. He believes this is good for developing muscle strength. It can be over done, however, and Bruin admonished that a trainer must be "specific"in trainingw the exercise provided should be as close to the work performed, or eventual performance, as possible. The fifth factor is metabolic capacity. The first 15% of improvement comes easy, according to Bruin. Continual work can usually bring 50% improvement in metabolic capacity. Exercise bouts for improvement of metabolic capadty should be provided 2-3 times per week over a 3 month period. This should consist of 3-6 works at about 3 minutes each at 85% maximum heart rate on a treadmill, or uphill. This would be at a heart rate of about 200 for the typical horse.
RESEARCH INVOLVING HIGH INTENSITY EXERCISE As a special guest lecturer at the ENPS Symposium, Dr. Gary Carlson, firm the University of California, Davis, spoke on the topic "Acid:buse and electrolyte alterations associated with maximal exercise." He began his discussion, however, with comments on the problems in research involving high intensity exercise. He cautioned that results from so-called maximal intensity exercise needs to be carefully evaluated because often there are significant incorrect assumptions made in interpretation of the results. The first problem he mentioned was one of timing in relation to exercisecFor example, blood collected within a~few minutes of the end of exercise is often reported as flit were exactly at the peak of exercise, when in fact, many of the parameters measured beg)m to C~ange immediately post exercise. Thus t~e data are incorrect to the extent that the parameter measured changes after exercise. Another problem is that often data are compared between parameter of blood collected either venous or arterial. Carlson maintained that there are often important differences. Also the site of collection can introduce differences in data. As an example, he pointed out that when arterial blood is taken, a declining pH is found with exercise, and a bicarbonate increase; when a venous blood sample is taken there is no bicarbonate change and acidosis is found. It is important to consider the core body temperature of the horse at the time of collection of samples. Temperature corrections are necessary for some parameters-- blood gas data being an example. The assumptions made about the various changes in physiological parameters during exercise influence the calculations made. Researchers, and those who interpret the results need to keep this in mind, according to Carlson.
135