Gerald Leigh Lectures 2024 - Optimising Youngstock Growth and Development
Beaufort Cottage Educational Trust hosted the annual Gerald Leigh Memorial Lectures at Tattersalls in Newmarket on June 11th. These lectures are in association with the Gerald Leigh Charitable Trust as a way of recognising Mr. Leigh’s achievements as a racehorse owner and breeder as well as continuing his passion for scientific knowledge and welfare of horses in the race industry and the equine industry as a whole.
Dr. Chavatte-Palmer provided a very insightful and interesting talk on the influence of maternal and environmental factors during the prenatal period on athletic performance. The lecture discussed the phenomenon of Developmental Origins of Health and Disease (DOHAD) which is demonstrated with the increasing evidence of the role in parental nutrition and environmental conditions, from periods preceding conception and throughout gestation, on phenotypic development in horses. She described how the nutritional environment before birth can affect the postnatal performance of the offspring as it is believed that nutrients can alter the way genes are expressed resulting in developmental trajectories that have repercussions on postnatal development. With a strong understanding and knowledge in DOHAD, nutritional strategies can be considered and developed to optimise youngstock growth and development. This is an exciting field as further research will potentially allow veterinarians and breeders to work cooperatively to optimise athleticism as well as the wellbeing and health of foals and mares.
Dr. Joe Pagan of the Kentucky Equine Research kindly visited from the U.S.A to discuss equine feeding management practices and equine nutrition in sports medicine. His first lecture discussed the effects of season on mare and foal nutrition. Through various studies some conclusions could be made and these conclusions do appear to be a global trend. It was found that colts are heavier and taller than fillies.
After 1 month of age, fillies were fatter than colts. Foals born in January and February were smaller at birth and grew more slowly in early life but by 150 days of age this lag disappeared. In addition, mare weight changes and body condition scores were related to season and management factors, as winter-foaling mares lost weight and had lower body condition post foaling than spring-foaling mares.
Dr. Pagan continued with a lecture on the right balance for optimal growth and development of youngstock. Recent research has shown that the health of the offspring of overweight mares may also be compromised. In addition, studies have shown that excess maternal nutrition during pregnancy can alter glucose and lipid (fat) metabolism in foals until 160 days of age. Another study reported a higher incidence of osteochondrosis (OC) in foals born to dams that were fed concentrates during gestation rather than forage.
A more recent study on the nutrition of the mare during the last trimester and subsequent foal health revealed some interesting observations. It was found that the growth of foals from 6-24 months of age was not affected by maternal diet and maternal undernutrition appeared to affect bone growth as foals from dams fed forage only had narrower cannon bones than foals from dams fed forage and barley. In addition, it was found that overfeeding negatively affected yearlings from mares fed barley and forage more than yearlings from broodmares fed only forage.
Finally, there was a decrease in insulin sensitivity and enhanced insulin levels suggesting insulin dysregulation in yearlings from mares fed both barley and forage and not yearlings from forage-only mares. Another exciting field of research that will also lead to greater cooperation of breeders and veterinarians in providing good health and wellbeing to foals and mares.
These lectures had the pleasure of hosting Paul Overton, who is an equine agronomist with a strong understanding of pasture management. His passion for his area of expertise and in helping with improving management of studs was abundant as he outlined the aims of pasture management that included the need to provide safe grazing pastures from parasites, colic and grass sickness, atypical myopathy and other ailments as well as to provide a safe area to exercise horses of all ages. In addition, he made clear that fresh leafy bite grass in the paddocks all year round is key.
We were reminded of the fundamentals of good basic pasture management that included a removal programme for muck, providing a dense leafy grass sward, sharing and mixing the paddock use with other livestock (sheep and cattle) and moving horses to various paddocks around the stud to maximise rest of all paddocks. To optimise paddock health, it should be remembered that all paddock management follows the horses around the seed, be guided by the weather rather than the calendar and work quickly to maximise rest periods. Finally, good simple paddock and grassland management can help a multitude of issues and every marginal gain is helpful.
Julian Dollar gave us an insight into a stud manager’s approach to soundness. It was an integral part of the lecture programme as it provided the audience with another perspective of stud management. He made it clear that a variety of factors must be considered when breeding and raising sound horses but two main criteria is a strong team and an attention to detail.
The team needed is one that is completely dedicated and passionate about their horses and should consist of a veterinary service, farriers, nutrition/feed and land management support. There must be a cooperative work ethic in order to provide the best all round management as possible. This team must strive for excellence and work on marginal gains.
A sound breeding and rearing programme starts with mating focusing on sound parents, especially the mare, to produce sound offspring. It is important to work with mother nature rather than interfering with it, thus focusing on a healthy environment. This strategy must be flexible that will allow one to provide the horses with a quality paddock.
The offspring should be between 55-60 kg and they should have a seamless transition from birth to exercise and living out. In addition, the foals should be monitored and assessed closely in order to achieve timely and maximum beneficial interventions that may include selective surgeries. Finally, it is believed that the perfect preparation for a yearling to go into training would be some controlled exercise combined with turnout the rest of the time.
Professor Jacqui Matthews, the director of Austin Davis Biologics, provided some sobering information on parasites and their resistance in the United Kingdom. She explained that intestinal worms are found in most grazing animals and most breeding premises are at high infection risk due to the presence of young animals grazing permanent pastures as well as having a history of interval deworming treatments.
In addition, wormer resistance is being reported in all major parasitic worms of horses. Therefore, it is vital to have control plans that include a risk-assessment approach. Professor Matthews made it very clear that we need to be concerned regarding parasites and their resistance to wormers on UK studs and we need to act now. She explained the action that is needed which includes evidence-based worm control. This approach requires risk assessment that allows one to identify potential issues in the management, the avoidance of all horses regularly being treated, the assessment of wormer effectiveness as well as the effectiveness of interventions.
With respect to the management, there are some principles behind reducing anthelmintic use. Good pasture hygiene can substantially reduce infective egg and larval stages in the environment and the lowering of this pasture contamination decreases parasites acquired when grazing. Pasture management must include:
Dung removal works! Full removal of dung at least once per week and place it away from pastures and water courses.
Maintain low stocking density
Rest pastures – ideally 12 months and avoid grazing foals on same paddocks every year
Consider grazing with ruminants between equine groups
With respect to treatment, make informed choices by using various tests such as faecal worm egg counts, faecal egg count reduction test, antibody-based tests to identify worms, and other tests. Ultimately, do not blindly treat horses without considering the reason for worming and assessing wormer effectiveness.
Professor Matthews followed up with a second lecture on integrating diagnostics into sustainable equine helminth control programmes. An integrated diagnostic-led control programme should consider:
Faecal egg worm count in late winter if grazing year-round. Recommend treatment if 200 or more eggs per gram and select your anthelmintic according to its sensitivity.
Tapeworm test in spring to identify individuals with tapeworm burdens and treat infected individuals as these horses will contaminate the paddocks with cestode eggs.
Late spring/early summer perform faecal egg worm count reduction test in order to assess anthelmintic effectiveness annually. Worm all horses that have FEC of >200 eggs per gram. Perform FEC test at day 0 and 14 days after treatment. Calculate the mean percentage.
Reduction in FEC between 0 and day 14 post treatment.
In late summer/early autumn perform tapeworm test to identify individuals that have, over the summer grazing period, accumulated high tapeworm burdens which may put them at risk of colic
In late autumn perform a small redworm test. In low infection-risk situations, test in late autumn/winter to identify individuals that do not require treatment for small redworm. Use in low-risk groups where owners usually apply all-group larvicidal treatments.
With good pasture management one can lower the selection for resistance, leading to a lowering the need for wormer treatments, a lowering in the proportion of horses that test positive and a lowering of paddock contamination; therefore, less horses are likely to be infected and more likely to have lower burdens.
With his 20 years of buying and selling thoroughbred bloodstock, Jamie Railton gave us insights into the business of foal purchasing. He discussed all of the variables that must be taken into account when selecting foals for purchase. Skill and experience are needed in spotting the foal with the potential to increase in value because of its physical improvement and its pedigree. He explained that a team of people are required as well as having a system to select foals; however, the system must be flexible and one must still want to continue to learn from the process and adapt and later the selection criteria. In addition, he discussed the need to reinvent oneself with the continuous change in the trends seen in the market.
Dr. Rebecca Mouncey is a veterinary surgeon and post-doctoral research fellow, currently investigating early-life determinants of performance and economics of thoroughbred breeding.
Dr. Mouncey discussed how musculoskeletal disease and injury remains the greatest barrier to thoroughbreds being retained within the industry and realising their maximum athletic potential, and is likely to have important economic consequences. She explained that lameness/musculoskeletal injury and disease are the most common barriers to performance. The causes of these conditions of developmental orthopaedic diseases are fractures and tendon/ligament injuries.
By improving the foal’s/yearling’s strength to withstand training and resist injury, while avoiding trauma, one can help with the prevention of these diseases. Unfortunately, there are still important knowledge gaps. It is possible to optimise musculoskeletal health during early-life with exposure during critical stages of growth and development that changes the distribution of cell types, alters metabolic function and ultimately altering the susceptibility and injury in adulthood.
Postnatally the period of greatest plasticity, response to external stimuli/exposures is during periods of most rapid growth and development. By 24 months of age, the horse is 96% mature bodyweight and 98% mature height and reached peak bone mass. There must be a balance in early-life exercise and activity as too little will delay musculoskeletal development and too much will cause tissue damage and trauma. We must always consider the animal’s growth, nutrition and exercise as a whole and not mutually exclusive.
Abigail Kent MRCVS from Rossdales Veterinary Surgeons, presented an interesting lecture on the diagnosis and treatment of limb deformities in foals. Dr. Kent is very knowledgeable in all aspects of equine elective and emergency surgery and has a particular interest in orthopaedics, specifically arthroscopy, angular limb correction and fracture repair.
Limb deformities in foals are developmental orthopaedic conditions, that can be subdivided into 2 major groups: 1) angular limb deformities, in which there is deviation, primarily in the frontal plane, originating at a joint and/or growth plate and 2) flexural limb deformities, in which there is persistent hyperflexion or hyperextension of the limb.
These conditions may be acquired or congenital and the aetiology is multifactorial. Early appropriate intervention is the key to the best outcome. Angular limb deformities are relatively common in foals and strategies for management, including surgical techniques, are well established. Early recognition, diagnosis and monitoring are essential in order to ensure optimal outcomes.
In cases of severe deformities that fail to respond adequately to conservative approaches (restricted exercise, splints, corrective hoof trimming and shoeing) other treatments such as timely surgery may be used. Transphyseal screws are effective for the corrections of both forelimb and hindlimb limb deformities. Flexural limb deformities can be treated conservatively with the mainstays of limited controlled exercise, nursing care, manipulation of the foot with trimming/shoes, splinting/casting and pain management.
Surgical intervention is typically recommended when conservative treatment is not effective or for severe or rapidly worsening deformities. The goal of surgery is to release tension in the restrictive musculotendinous unit, allowing for greater stretch and more normal range of motion of the affected joint.
In conclusion, all the contributors provided the participants a very interesting and illuminating day. This event highlighted the lengths that all stakeholders and the veterinary profession are taking to constantly improve the health and wellbeing of the horses and the health of the race industry.
KER Nutrition Conference - management of gastrointestinal and metabolic diseases
Kentucky Equine Research (KER) has maintained a prominent international presence in the nutrition research community for the past 20 years. Research trials have been conducted at the company’s research farm since the late 1980s, and results of this research have been published in numerous peer-reviewed journals and proceedings of scientific conferences.
Mark Llewellyn (European Trainer - issue 22 - Summer 2008)
Kentucky Equine Research (KER) has maintained a prominent international presence in the nutrition research community for the past 20 years. Research trials have been conducted at the company’s research farm since the late 1980s, and results of this research have been published in numerous peer-reviewed journals and proceedings of scientific conferences.
More importantly, findings from these studies have been put to use in the formulation of feeds for KER’s global network of feed manufacturers. The KER Nutrition Conference, held on the 16th and 17th of April in Lexington, Kentucky was attended by 130 guests, including feed manufacturers, sales representatives, veterinarians, nutritionists, and academics from 16 countries.
This year’s conference focused on the management of gastrointestinal and metabolic diseases. Founder and President Dr. Joe Pagan began by introducing Dr. Larry Lawrence, senior nutritionist at KER, who presented an in-depth review of the development of the gastrointestinal system. Dr. Lawrence addressed the changes that occur as a foetus grows within the womb and as the foal matures and begins to digest a diet of forages and concentrates.
A thorough explanation of the physical, enzymatic, and fermentative changes that occur to the gastrointestinal tract during gestation and growth gave conference attendees a better understanding of the importance of proper feeding. Colic, the most pervasive disease of the gastrointestinal tract in horses, was the next topic of discussion.
Dr. Nathaniel White, the Jean Ellen Shehan Professor and Director at Virginia Tech’s Marion duPont Scott Equine Medical Center and a world-renowned expert on equine gastrointestinal disorders, reviewed the prevalence of colic in today’s equine population.
He mentioned several risk factors: breed and gender predilection, dietary management, and other environmental and management practices. Additional risk factors such as previous colic episodes, parasitism, cribbing, gestation, transport, and anesthesia were touched on as well. In addition, he chronicled measures to prevent the syndrome. In a related lecture given later in the day, Dr. White addressed standard treatment protocols for colic including decompression of the stomach or intestine, use of systemic analgesics, strategies to promote gut motility and hydration, and treatment of impactions.
He then discussed proper nutrition of the horse after an episode of colic. A review of enteral (traditional) and parenteral (intravenous) nutrition followed. The speaker noted that although enteral nutrition is preferred, parenteral nutrition can provide long-term nutritional support, and stated that horses have been kept on complete parenteral nutrition for up to a month and have been able to maintain or gain weight. Dr. Frank Andrews, section chief of the department of large animal clinical sciences at the University of Tennessee College of Veterinary Medicine, spoke about the diagnosis and treatment of gastric and colonic ulcers in horses.
Gastric ulcers have been studied for several years and their prevalence among horses is well documented. Though colonic ulcers occur less frequently than gastric ulcers, Dr. Andrews listed several nonspecific signs including mild intermittent or recurring colic, lethargy, and partial anorexia that may hint at a problem.
As the problem worsens, so do the signs with complete anorexia, fever, diarrhoea and associated dehydration, and weight loss is common. Dr. Peter Huntington, the director of nutrition for KER’s Australasian branch, spoke to conference attendees about recent advances in laminitis research.
Despite the fact that a complete understanding of laminitis and its complex pathophysiologic processes remains elusive, laminitis seems to occur as a consequence of inflammatory, vascular, and enzymatic interactions. Dr. Huntington explained that a trend in laminitis research involves interest in metabolic or endocrine events that lead to laminitis. In regard to prevention, Huntington pointed out that genetic research could identify at-risk horses, and therapies such as intracecal buffering are helpful in preventing the shifts in cecal pH that can lead to laminitis.
In closing the first day of presentations, Dr. Joe Pagan spoke about gastrointestinal health, the foundation of which, he made clear, is good-quality forage. He identified four primary factors that affect forage quality: plant species, stage of maturity at time of grazing or baling, latitudinal effects (tropical versus temperate forages), and inhibitory substances that reduce digestibility of fibre and minerals.
The buffering capacity of certain forages is a burgeoning area of interest among equine nutritionists. Pagan explained that certain feeds and forages can counteract changes in gastric pH, thereby playing an important role in the prevention of gastric ulcers in horses. This ability to resist changes in pH is called buffering capacity.
Alfalfa hay has been shown to be effective in reducing the severity of gastric ulcers by providing superior buffering capacity when compared to grass hay. The second day of the conference featured several topics related to metabolic conditions. Dr. Anna Firshman, a large animal internist at Oregon State University, began the day with a thorough overview of insulin resistance, a problem that has been receiving much attention recently as it is thought to be closely associated with other diseases such as equine metabolic syndrome, equine Cushing’s disease, laminitis, hyperlipedemia, and osteochondritis.
Firshman reviewed the mechanisms of glucose transport in muscle and fat, and then described the tests that are currently available to assess insulin resistance in horses. Firshman concluded that though tests may become useful clinical means to assess the degree of insulin resistance and responses to treatments, there is no one ideal test that is both practical and accurate. Dr. Frank Andrews then settled onto the stage for a second presentation.
He presented a detailed outline of the metabolic-related conditions that most commonly affect horses: equine Cushing’s disease and equine metabolic syndrome. For each condition, he methodically outlined the clinical signs, diagnosis, course of treatment, and management goals.
For equine Cushing’s disease, Andrews stated that diagnostic tests, when coupled with clinical signs, will confirm the presence of advanced disease but may not be sensitive enough to detect early stages of the disease. KER has been instrumental in developing ideal growth curves for equine athletes. Dr. Clarissa Brown-Douglas reviewed the research compiled by KER over the last two decades, stressing the importance of properly feeding young, growing horses.
To fuel maximum growth, breeders often feed young horses large amounts of grain. However, rapid growth achieved by overfeeding energy has been implicated in developmental orthopedic disease (DOD). The source of energy may be important for many young horses. Those that experience an exaggerated and sustained increase in circulating glucose or insulin in response to a grain meal might be predisposed to osteochondritis dissecans (OCD).
Research conducted by KER suggests that hyperinsulinemia may influence the incidence of OCD. Based on the results of this research, young horses should be fed concentrates that produce low glycemic responses such as feeds in which energy is provided by fat and fermentable fibre sources (beet pulp and soy hulls). Once the audience had an understanding of the metabolic disorders that affect horses, Dr. Joe Pagan identified a commonality among them.
All of the problems are either triggered or aggravated by excessive starch and sugar intake. After a brief review of carbohydrates in horse feeds, Pagan gave general feeding recommendations for each disorder, noting that high-fat, low-starch feeds are appropriate for certain disorders such as tying-up but may not be recommended for others such as equine metabolic syndrome.
Once a horse has been diagnosed with a metabolic disease, an equine nutritionist and veterinarian should team up to formulate a suitable diet. Maintaining appropriate body condition is usually a trick for those who own horses diagnosed with a metabolic condition. These horses are often too thin or too fat. Dr. Laurie Lawrence, a professor at the University of Kentucky, addressed energy balance and methods to increase or decrease body condition.
She presented reasonable timelines for weight gain and emphasised management programs that allow ample time for weight gain so horses are not fed extremely high levels of concentrate. Lawrence also noted that as a horse is adapted to a diet with increased feed intake, there may be a fairly immediate increase in body weight due to changes in gut fill and/or gastrointestinal tissue mass, followed by a period of slower body weight change. Change in condition score will frequently lag behind change in body weight. Lawrence classified obese horses into two groups: those that have become fat temporarily because of a change in management or food availability, and those that have been fat for a long time.
Adjusting the body weight of the first group, Lawrence explained, is usually much less complicated than reducing the body weight of the latter group, and she gave a step-by-step approach to helping these horses lose weight. Kathryn Watts of Rocky Mountain Research and Consulting in Colorado gave the final presentation of the conference. She explained differences in the nonstructural carbohydrate (NSC) content in various forages, and how stage of growth and environmental factors might significantly alter the amount of NSC present. Watts advised that all of the most commonly recommended varieties of grass have the potential to contain high levels of NSC under certain conditions, but stands of these grasses can be managed for lower NSC concentration.
This year’s Kentucky Equine Research Nutrition Conference offered valuable information about gastrointestinal and metabolic problems affecting horses today. For those individuals unable to attend the KER conference, proceedings are available by logging on to www.shop.ker.com. This 150-page booklet contains a detailed paper for each of the lectures presented. As part of its dedication to world-class nutrition, KER has been recruited to help formulate and distribute feeds for the equine athletes of several international competitions.
In 2004, KER was named the official nutritionist of the United States Equestrian Federation. In this capacity, KER nutritionists use their knowledge to sort out nutritional challenges encountered by the world’s most elite equine athletes, those that represent the United States in international competition. For more information on KER, visit www.ker.com.