Sarah L. Ralston

Insulin and glucose regulation.

Abnormally high or low blood glucose and insulin concentrations after standardized glucose tolerance tests can reflect disorders such as pituitary dysfunction, polysaccharide storage myopathies, and other clinical disorders. Glucose and insulin responses, however, are modified by the diet to which the animal has adapted, time since it was last fed, and what it was fed. Body fat (obesity), fitness level, physiologic status, and stress also alter glucose and insulin metabolism. Therefore, it is important to consider these factors when evaluating glucose and insulin tests, especially if only one sample it taken. This article describes the factors affecting glucose and insulin metabolism in horses and how they might influence the interpretation of standardized tests of glucose tolerance.

Digestion in the aged horse

Changes in digestion associated with advanced age have been described in rats, dogs and humans.Z.4.8.9.11.]2The most commonly reported alterations are an increase in the efficiency of protein digestion and utilization, and a decreased absorption of calcium in aged humans and dogs. 1,4.9,]2 There have been virtually no controlled studies of digestion and metabolism in aged horses and little is known concerning their nutritional needs. 1° If changes in digestion are proven to occur at an advanced age, diets may be designed to maximize nutrient utilization. This study was designed to investigate differences in digestion of pelleted alfalfa between aged (>20years-old) and young (< 10-years-old) horses.

Field evaluation of a feed formulated for geriatric horses

Summary Weight maintenance and blood chemistry parameters of geriatric (>20 yrs) horses and ponies housed at a farm for retired horses were compared between animals fed a 14% protein pelleted/extruded feed (ES) formulated specifically for geriatric horses versus those fed the textured sweet feed used at the facility. A total of 48 geriatric horses and 3 ponies were initially examined, 28 of which were assigned to be fed ES, the other 23 continued to be fed an 8.5% protein textured sweet feed mix (SF). Horses and ponies were fed the feeds in amounts estimated to be necessary for weight maintenance or gain according to initial body condition scores, with hay being offered free choice. The horses were weighed, assigned body condition scores and had blood drawn for complete blood counts and blood chemistry panels in December, 1992 before feed changes were initiated. The same measurements were taken on surviving horses and ponies three months after the feed changes had been made (March, 1993). For statistical analyses, data were grouped according to the animals initial body condition score. Horses (n=17) and a pony with initial body condition scores of three or less (Group 1) which were fed ES had greater weight gain (ES: 32kg±4; SF: −9kg±7; p .2) in hemoglobin over the same period. Blood phosphorus was increased (December: 2.21±.08 mg/dl; March: 2.48±.07 mg/dl; p .2) between animals fed ES (n-9) versus SF (n=9) in December or March. However Group 1 animals fed ES experienced greater weight gains (p .2) between diets in March. Blood urea nitrogen (BUN) was higher in ES fed horses than the SF fed horses in March in both Group 1 (p Horses which were fed the ES were subjectively assessed by the farm manager to have better hair coats and higher activity levels than when they had been fed textured sweet feed and relative to horses that were not fed ES. Geriatric horses, especially those unable to maintain adequate weight on standard rations in the absence of hepatic or renal disease, appear to benefit from the special formulation of ES.

Clinical Nutrition of Adult Horses

Horses suffering from trauma, sepsis, and severe burns need 12% to 16% of protein (dry matter basis) in their diet. Since reduced appetite may be a problem, relatively energy dense (greater than 2 Mcal DE/kg) feeds should be offered. In hepatic failure, maintenance protein requirements (8% on a dry matter basis for adult horses) should be met with feeds that are high in short branched-chain amino acids and arginine but low in aromatic amino acids and tryptophan (for example, milo, corn, soybean, or linseed meal) in addition to grass hay. Vitamins A, C, and E should also be supplemented. In cases with renal failure, protein, calcium, and phosphorus should be restricted to maintenance or lower levels. Grass hay and corn are the best feeds for horses with reduced renal function. Do not offer free-choice salt to horses with dependent edema from uncompensated chronic heart failure. Following gastrointestinal resection, legume hay and grain mixtures are the feeds of choice. Horses with diarrhea should not be deprived or oral or enteral alimentation for prolonged periods of time. Liquid formulas may be used if bulk or gastrointestinal motility are a problem. Apple cider vinegar and a high grain diet may reduce the incidence of enteroliths in horses prone to this problem. Pelleted feeds will reduce fecal volume and produce softer feces for horses that have had rectovaginal lacerations or surgery. Horses with small intestinal dysfunction or resection should be offered low residue diets initially, but long-term maintenance requires diets that promote large intestinal digestion (alfalfa hay, vegetable oil, restricted grain). Geriatric horses (greater than 20 years old need diets similar to those recommended for horses 6 to 18 months old.

Equine viral arteritis at a veterinary teaching hospital

Abstract An outbreak of equine viral arteritis (EVA) occurred at a veterinary teaching hospital in the summer and autumn of 1984. Clinical signs were observed in 16 out of 61 hospitalized horses and included ventral, limb and preputial edema, mild conjunctivitis with lacrimation, pyrexia and increased respiratory and heart rates. Of 16 clinically affected horses, 13 were undergoing experimental abdominal surgery and/or were involved in digestion experiments; 9 of the 13 were > 20 years of age. The three other clinically affected horses were client animals. Thirteen client horses developed serologic titers to equine arteritis virus in the absence of clinical signs. The risk of infection was associated with close contact, involvement in the experimental studies being conducted and length of hospitalization. The disease was mild, limited in spread and successfully controlled by quarantine.

Digestion in aged horses—Revisited

Research on digestion in aged (>20 yrs old) Quarterhorse and Thoroughbred horses in the mid-1980’s revealed that the population studied at that time had reduced apparent digestion of protein, phosphorus and fiber relative to younger horses fed pelleted alfalfa.1 The digestive profile of the aged horses was very similar to that reported for horses which had had 90% resection of the large colon2,3. In two subsequent digestion trials on aged horses conducted in New Jersey in the 1990’s the reductions of digestibility in especially protein were not as apparent. In trial 1, conducted in 1990, eight light horse mares > 19 years old were used in a simple crossover design to compare digestibility of a commercial textured sweet feed (OM) and one formulated specifically for aged horses (ES). The grains were fed in amounts calculated to provide 50% of the mare’s recommended caloric requirements (NRC, 1989) for maintenance, the rest of the ration being provided as long stem hay. The mares were adapted to the rations for 2 weeks and then subjected to a standard 5 day digestion trial, during which intake was recorded and all feces were collected and weighed, with subsamples taken for nutrient analyses at a commercial laboratory (DHIA, Ithaca, NY). There were differences in apparent digestibility between the two rations. Protein, calcium and phosphorus intakes were higher in ES fed horses than on the OM. Mares on the OM were, as previously reported in aged horses, in low to negative phosphorus balance (-8.1%±4.3) but were in positive balance on the ES (13.3 ±4.4). Calcium apparent digestion was also higher in ES fed horses (OM: 10±6; ES: 33±4, p<.05). Crude protein apparent digestion in OM fed mares was lower (OM: 63.9±1.0 vs ES: 71.5±0.7, p<.05) however it was still within the normal range of protein apparent digestion reported for horses. The differences between the two rations were probably due to the higher protein, calcium and phosphorus intake in the ES ration (Table 1).

Factors in the control of feed intake of horses and ponies

Ponies are large nonruminant herbivores which are capable of utilizing the products of both enzymatic digestion in the small intestine and bacterial fermentation (volatile fatty acids, VFAs) in the cecum and large colon as sources of metabolizable energy. Recent studies have demonstrated that ponies utilize nutrient stimuli from both carbohydrate and fat digestion in the small intestine and VFAs in the cecum and large colon in the control of meal frequency. These animals, however, rely primarily upon oropharyngeal and external stimuli to control the size and duration of meals. This is perhaps an adaptation to a feeding pattern of small frequent meals and food sources which provide significant amounts of nutrients to the animal system only after microbial fermentation in the hind gut. Nutrient cues which are operant in controlling feed intake in omnivores, carnivores, and ruminants appear to be important primarily in the regulation of meal frequency and long-term energy balance in the equine animal. The emphasis on oropharyngeal stimuli in the immediate control of feed intake of ponies reflects the unusual digestive physiology of these animals relative to other species studied to date.

Feeding the rapidly growing foal

Summary Young, rapidly growing foals can be fed rations that sustain good growth rates, as long as the proper mineral balance is included. Rations causing significant postprandial hyperglycemia/hyperinsulinemia, such as sweet feeds, should be avoided if the foal is from a bloodline known to be predisposed to osteochondritis dissecans (OCD). Protein intake should not be less than 14% dry matter intake in the first year of life in order to promote optimal growth rates and development. Calcium, phosphorus, copper, and zinc intakes should also be increased in the first 2 years of life.

Mineral intake and hair analysis of horses in Arizona

Summary To evaluate the effect of diet on hair mineral content, 61 feeds, 31 pasture grasses, 29 mineral supplements, 31 water samples and hair samples from 391 horses from 31 ranches in Arizona were analyzed for fifteen minerals. Based on dietary histories and estimated intakes when free choice access was involved, mineral intake of the horses was calculated and compared to mineral content of the hair. Data were evaluated by regression analysis for correlations between hair and dietary minerals and variations in hair mineral content attributable to coat color, age, sex and breed. 11 , 12 , 13 , 14 There were differences (P 17 , 18 , 20 , 21 and may offer better insight to the interpretation of mineral nutrition than simple one to one correlations.

Disseminating Equine Research and Teaching Videos Through the Institutional Repository: A Collaboration

Institutional repositories manage and disseminate a Universitys scholarly output and provide a multitude of benefits to the organization and society. Rutgers University Libraries is actively expanding its repository to include materials with scholarly merit that are currently siloed in academic departments or otherwise unpreserved and unavailable to the public. This article describes a collaboration between Rutgers Libraries faculty and Rutgers teaching faculty which is enabling discovery of a significant collection of video data relating to equine behavioral responses. The article describes the research, the repository tools, and the process of developing and customizing metadata to bring this collection to light.