H. F. Hintz

Nutritional quality of gorilla diets: consequences of age, sex, and season

We tested the effects of age, sex, and season on the nutritional strategies of a group of mountain gorillas (Gorilla beringei) in the Bwindi Impenetrable National Park, Uganda. Through observations of food intake of individual gorillas and nutritional analyses of dietary components over different seasons and environments, we estimated nutrient intake and evaluated diet adequacy. Our results suggest that the nutritional costs of reproduction and growth affect nutrient intake; growing juveniles and adult females ate more food and more protein per kilogram of metabolic body mass than did silverbacks. The diets of silverback males, adult females, and juveniles contained similar concentrations of protein, fiber, and sugar, indicating that adult females and juveniles did not select higher protein foods than silverbacks but rather consumed more dry matter to ingest more protein. Juveniles consumed more minerals (Ca, P, Mg, K, Fe, Zn, Mn, Mo) per kilogram of body mass than adult females and silverback males, and juveniles consumed diets with higher concentrations of phosphorous, iron, and zinc, indicating that the foods they ate contained higher concentrations of these minerals. Seasonally, the amount of food consumed on a dry weight basis did not vary, but with increased frugivory, dietary concentrations of protein and fiber decreased and those of water-soluble carbohydrates increased. Energy intake did not change over the year. With the exception of sodium, gorillas ate diets that exceeded human nutrient requirements. A better understanding of the relative importance of food quantity and quality for different age–sex classes provides insights into the ways in which gorillas may be limited by food resources when faced with environmental heterogeneity.

A preliminary study of two methods of weaning foals

The reactions of 8 pony foals weaned individually into stalls were compared to those of 14 weaned into stalls by pairs. Blood samples were taken just before weaning, 15 min after weaning, and 6 and 24 h after weaning, and analyzed for cortisol levels. Each pony was observed for six 15-min periods: before weaning, immediately after weaning, and at 6, 12 and 24 h and 1 week after weaning. The behaviors of neighs, steps, urinations and defecations were recorded. These were determined as follows: neighing (pre-weaning = 0.3 ± 0.2; post-weaning = 20.1 ± 3.7); steps (pre-weaning = 18.3 ± 2.7; post-weaning = 95.2 ± 10.3); urinations (pre-weaning = 0 ± 0; post-weaning = 0.67 ± 0.19); defecations (pre-weaning = 0.6; post weaning = 0.7 ± 0.2). The frequency of these behaviors was significantly higher in the foal immediately after weaning than before (P < 0.05), indicating that weaning, per se, was stressful. Between groups, the only significant differences were found in vocalization rates. In the floals weaned alone, the incidence of neighs was more than those weaned as pairs immediately after weaning (alone = 30.9 ± 7.2; paired = 14 ± 3.7 neighs/15 min; P < 0.05), at 12 h post-weaning (alone = 4 ± 1; paired = 1.5 ± 0.615, min; P < 0.05) and at 1 week post-weaning (alone = 1.6 ± 0.4; paired = 0.4 ± 0.2; P < 0.05). No significant differences occurred between pre-weaning (17 ± 2 ng ml−1) and post-weaning (18 ± 3 ng ml−1) plasma cortisol, nor between cortisol levels of ponies weaned alone and those weaned in pairs. Weaning in pairs appears to be less stressful than weaning individually. Behavioral methods thus appear to be useful in determining the effects of different management techniques on foals.

A note on the comparison of digestion by New World camels, sheep and ponies

Digestion trials were conducted with four ponies, two sheep and two New World camels (one llama and one guanaco) given alfalfa pellets and a complete pelleted hay-grain diet. The New World camels were significantly more efficient in the digestion of dry matter, neutral-detergent fibre, acid-detergent fibre and cellulose than the sheep or ponies.

Nutrition and Equine Performance

Some aspects of energy, protein and vitamin E nutrition of the performance horse are discussed. The amount, dietary source and time of ingestion of energy before exercise can influence performance. In 1989 the National Research Council (NRC) increased their estimates of energy required by racehorses. Recent studies indicate that the increase was reasonable. Many factors, however, can influence energy requirements. Therefore, the best measure would be body weight and composition of the horse. A proper balance of soluble carbohydrate, fiber, fat and protein is essential. Some guidelines are presented. The amount and type energy source given before exercise can influence level of plasma glucose and free fatty acids during exercise, but the effects of these changes in the concentration of metabolites remains to be determined. There is no evidence that increased dietary concentrations of protein are needed and, in fact, may impair performance. Supplemental histidine (to enhance carnosine levels) or carnitine appear to be of limited value for horses fed conventional diets. Dietary concentrations of vitamin E less than the 80 IU/kg recommended by NRC seem to adequately protect against exercise-induced peroxidation. The NRC value may be justified on the basis of immune response, but further studies are needed. Vitamin E has been shown to be involved with familial equine degenerative myeloencephalopathy and may be involved with equine motor neuron disease, a condition considered to be similar to amyotrophic lateral sclerosis in humans.

Calcium excretion in feces of ungulates.

1. Fecal excretion of calcium was examined in 122 individual ungulates representing 7 species of Equidae, 3 species of Tapiridae, 3 species of Rhinocerotidae, 2 species of Elephantidae, 2 species of Hippopotamidae, 12 species of Bovidae, 2 species of Cervidae, 3 species of Camellidae and 1 species of Giraffidae. 2. Animals were fed timothy hay, a low calcium diet or alfalfa hay, a high calcium diet. 3. In a few cases oat straw or prairie hay was used instead of timothy hay. 4. Samples of feces were obtained from individuals daily for 4 days following a 20 day dietary equilibration period. 5. Feces of equids, tapirs, rhinoceros and elephants had a lower calcium concentration and a lower Ca/P ratio than feces of ruminants when the animals were fed diets of equivalent calcium content. 6. The findings suggest that the non-ruminant ungulate equids, tapirs, rhinoceros and elephants absorb a larger proportion of dietary calcium than ruminants do.

Some effects of maternal deprivation on maintenance behavior, spatial relationships and responses to environmental novelty in foals

Abstract Six artificially reared foals and 6 age-matched controls reared by their own mothers were studied. When 2–4 months old the ponies were studied in 2 environments, a pasture with which they were familiar and a paddock where they had not been prior to testing. The 2 groups of ponies used the pasture on alternate days. The focal animal method was used to determine time spent grazing, standing and lying, the number of steps taken, and to record the incidence of scratching, urinations, defecations, vocalizations and contacts between ponies. The presence of another pony within 1 m of the focal pony was also recorded. There were no differences in major activities between the 2 groups. Orphan foals spent 40/h grazing. Mothered foals spent 41 min/h. Orphan foals spent 5 min/h lying down; mothered foals spent 6 min/h lying down. Orphan foals spent 8 min/h standing; mothered foals spent 6 min/h standing. The orphans took 404 steps/h; the mothered foals 450 steps/h. The number of contacts were not different: the orphan foals touched other foals 5 times/h; the mothered foals touched 4 times/h. There was a significant difference in the number of times the foals scratched. The orphan foals scratched 9 times/h; the mothered foals scratched only 5 times/h. The orphan foals were within 1m of another foal 41 min/h; the mothered foals were within 1m of another foal only 12 min/h, but if the time that the mothered foals spent within 1 m of their mothers (19 min/h) and within 1 m of other mares (5 min/h) is added to the time spent with other foals, the total (36 min/h) is not significantly different from the time spent by orphan foals with other foals. This indicates the innate tendency of foals to form herds, that is, to be gregarious. Each pony foal was placed alone in a novel environment; a small paddock. The mothered foals were significantly more active (508 steps/5 min), neighed more often (19 neighs/5 min) and defecated more often (2 defecations/5 min) than orphan foals (149 steps, 5 neighs and 0 defecations/5 min). The mothered foals were apparently more stressed when in a novel environment in the absence of their mothers. In a second and third 5-min period, the foals were exposed to a human or to a strange pony. The orphan ponies did not spend more time with the human (within 1 m) than the mothered ponies, nor did the mothered ponies spend more time with the strange pony than the orphans. The mothered foals continued to be significantly more active and more vocal in the second and third periods than the orphan foals.

Ammonia Intoxication and Intermediary Metabolism

Summary Ammonia intoxication of rats markedly increased blood glucose, pyruvate. α-ketoglutarate and ammonia concentrations. Ammonia intoxication of horses produced similar changes in the blood metabolites and the sequence of these events was as follows: blood ammonia increased and α-ketoglutarate decreased during the first 2 hr, but then increased very rapidly. These changes were followed by increases in blood glucose and pyruvate concentrations. Ammonia intoxication did not affect liver mono-, di- or triphosphates of adenine and guanine. These findings indicate that a primary lesion in ammonia intoxication is a derangement of intermediary carbohydrate metabolism. This research was financially supported by a grant from The Nutrition Foundation and U.S. Public Health Service, Grant No. GM-16538-01. The authors acknowledge the assistance of Mabel Goetchius, John Milner and Gary Gibson.

Glucose tolerance in the horse, pony and donkey

Abstract Glucose tolerance tests were conducted on seven donkeys, seven horses and seven ponies. The average initial plasma glucose value for all equines was 86.8 mg/dl. The values increased approximately two-fold by 2 hours after oral glucose administration. Plasma glucose values for horses and ponies returned to near initial values within 6 hours (87 and 82 mg/dl, respectively), but the donkeys remained higher (114 mg/dl) (P

A comparison of the mineral composition of milk of domestic and captive wild equids (Equus przewalski, E. zebra, E. burchelli, E. caballus, E. assinus)

Milk samples were obtained in early and/or late lactation from Przewalski horses, Hartmanns zebras, Grants zebras, domestic horses, ponies and a mule mare made pregnant by embryo transfer. Samples were compared for their content of total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper, zinc and iron. Milk from the Przewalski horses, Hartmanns zebra and the domestic horse had similar mineral composition and the content of minerals was higher in early than in late lactation. Milk from the domestic mule contained the lowest concentration of calcium, phosphorus and zinc but the highest concentration of magnesium, sodium and potassium. Milk from the Grants zebras contained more sodium than potassium, unlike milk from Przewalski horses, Hartmanns zebras or domestic horses in which there was more potassium than sodium.

Digestibility by ponies of oat straw treated with anhydrous ammonia

The digestibility of oat straw treated with anhydrous ammonia was studied in four Shetland-type ponies in a 4×4 Latin square experiment. The experimental diets which contained soya bean oil meal, corn, sugarcane molasses, and 65% straw were: (1) straw treated with anhydrous ammonia, (2) untreated straw, (3) untreated straw plus urea, (4) untreated straw plus soya bean oil meal. Digestibility of the dry matter was 15% greater ( P P