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Biomedical subjects

H F Hintz

Publications and source records attributed to H F Hintz.

At least 37 records · Page 2Linked to original sources
PubMed1986

Lactation in the horse: the mineral composition of mare milk.

Changes in the mineral composition of mare milk during lactation were studied. Milk samples were obtained from five Thoroughbred mares one to three times weekly from the first to the eighth week of lactation and from two of the mares for an additional 8 wk. Samples averaging 500 mL were obtained after oxytocin was administered to the mares. Each sample was analyzed for total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper and zinc. The concentration of all constituents except sodium and potassium decreased throughout lactation. The rates of decline of ash, calcium, phosphorus and magnesium concentration were similar, but the rates of decline of the other elements differed. Thus, the mineral composition of mare milk should be described in terms of the stage of lactation of the mare. The total solids and ash content of mare milk were 12 and 0.61% respectively, at the end of the first week of lactation, 10.5 and 0.45% at 4 wk, 10 and 0.38% at 8 wk and 10.2 and 0.32% at 16 wk. The calcium, phosphorus and magnesium concentrations at the end of the same periods were 1345, 943 and 118 micrograms/g of milk at 1 wk; 1070, 659 and 86 at 4 wk; 831, 574 and 58 at 8 wk and 700, 540 and 43 micrograms/g of milk at 16 wk. Copper and zinc concentrations were 0.85 and 3.1, 0.55 and 2.2, 0.29 and 1.9 and 0.28 and 1.8 microgram/g of milk at 1, 4, 8 and 16 wk, respectively.

Animals↗
PubMed1986

Equine energetics. I. Relationship between body weight and energy requirements in horses.

Energy balance studies using indirect calorimetry were conducted with four mature equids ranging in weight from 125 to 856 kg. Each animal was fed three different levels of intake of the same diet. The amounts of digestible and metabolizable energy required for zero energy balance were determined by calculating regression equations for energy balance against energy intake. It was concluded that the maintenance requirements of equids vary linearly with body weight. No advantage was found for the use of weight for the comparison of equids within the range studied. The digestible energy (DE) requirement for equids confined to metabolism stalls was DE (kcal/d) = 975 + 21.28 X W where W equals body weight in kg. If a factor for activity similar to that suggested by the National Research Council was included, the requirement could be calculated by the equation: DE (kcal/d) = 1,375 + 30.0 X W.

Animals↗
PubMed1986

Equine energetics. II. Energy expenditure in horses during submaximal exercise.

Energy expenditure was measured in four geldings (433 to 520 kg) during submaximal exercise on a racetrack using a mobile open-circuit indirect respiration calorimeter. A total of 304 5-min measurements of O2 consumed and CO2 produced were taken. Measurements were made with and without riders. The amount of energy expended by the horses was exponentially related to speed and was proportional to the body weight of the riderless horse or the combined weight of the horse plus rider and tack. Total energy expended by the four horses walking, trotting, cantering was best described by the equation: Y = e3.02 + .0065X where Y = energy expended (cal X kg-1 X min-1) and X = speed (m/min). Digestible energy (DE) required above maintenance was calculated as (Formula: see text).

Animals↗
PubMed1986

Composition of milk from pony mares fed various levels of digestible energy.

Twenty-two pony mares were fed one of three diets that provided 93.0, 74.8 or 57.2 kcal of digestible energy (DE) per kg body weight per day. Milk samples were taken at 14 day intervals. A total of five samples were taken from each mare. The samples were analyzed for total solids, crude protein, lactose, total lipids, ash, calcium and phosphorus. Gross energy was calculated from composition data. Increases in energy intake decreased the concentration of total solids, protein, fat and gross energy of mare's milk. Energy intake had a greater influence on the mare's body condition than on milk energy production. It was concluded the objective of a feeding program for a lactating mare should be to keep the mare in a desirable body condition rather than to influence milk composition or production.

Animal Feed↗
PubMed1986

Metabolism of some essential minerals in ponies fed high levels of aluminum.

The effect of dietary aluminum on the absorption, retention and pathways of excretion of calcium, phosphorus, magnesium, zinc, iron and copper was studied in balance trials in mature ponies in a three by three latin square experiment. A basal diet consisting of one third each of oats, beet pulp and a commercial pelleted, complete horse ration and containing 336 ppm aluminum was supplemented with AlC1(3) . 6H2O. The middle and high level aluminum diets contained 1370 and 4500 ppm aluminum respectively. There was little difference in effect between the middle level aluminum and basal diets. The ponies were in negative phosphorus balance when fed the high level aluminum diet because phosphorus absorption was suppressed. Calcium absorption was unaffected by aluminum intake but the ponies were in negative calcium balance when fed the high aluminum diet due to the greater urinary excretion of calcium by the ponies. Presumably, calcium was excreted in urine because it was not utilized in the formation of bone crystal due to the lack of phosphate. Plasma calcium was elevated and plasma phosphorus was depressed when ponies were fed the high aluminum diet. Plasma hydroxyproline concentration was increased suggesting that bone turnover was increased due to aluminum effects on phosphorus and calcium metabolism. Magnesium, zinc, iron and copper metabolism were unaffected by aluminum intake.

Aluminum↗
PubMed1985

The effects of caloric dilution on meal patterns and food intake of ponies.

In order to determine if horses will increase their intake in response to caloric dilution, four pony geldings were fed ad lib a mixed grain diet either undiluted (3.4 Mcal/kg of digestible energy) or diluted (wt/wt) with 25% sawdust (2.6 Mcal/kg) or with 50% sawdust (1.7 Mcal/kg). The mean daily caloric intake was 17,457 kcal (3.4 Mcal diet), 17,546 kcal (2.6 Mcal diet) and 12,844 kcal (1.7 Mcal). The mean time spent eating was 246 (3.4 Mcal), 351 (2.6 Mcal), and 408 (1.7 Mcal) minutes/day. Meal size increased and meal frequency decreased with increasing dilution. The median long survivorships of intermeal intervals were 6.4 min (3.4 Mcal), 3.95 min (2.6 Mcal) and 4.91 min (1.7 Mcal). Ponies responded to caloric dilution by increasing the volume of intake to maintain caloric intake when the diet had 25% diluent. When the diet was diluted by 50%, intake was increased, but not at a rate adequate to maintain caloric intake. However, the ponies were able to maintain body weight.

Animals↗
PubMed1985

Feed preferences of ponies.

Preference trials were conducted with mature ponies. In Trial 1, oats were compared with oats plus sucrose. Four of six pony geldings selected oats plus sucrose, but one pony demonstrated a dislike for sucrose and one selected from the bucket on the right side regardless of content. Oats, maize, barley, rye and wheat were compared in Trial 2 using six mature pony mares. Oats were the preferred grain, with maize and barley ranking second and third respectively. Wheat and rye were the least preferred. Even though the ponies demonstrated preference, the total intake at a given meal was not greatly depressed when only the less palatable grains were fed. In Trial 3, pony mares selected a diet containing 20 per cent dried distillers' grain and 80 per cent of a basal mixed diet of maize, oats, wheat bran, soybean meal, limestone and molasses over 100 per cent basal mixed diet, but selected the basal diet over diets containing 20 per cent blood meal, beet pulp or meat and bone meal and 80 per cent basal diet. They did not differentiate against diets containing 20 per cent alfalfa meal or 10 or 5 per cent meat and bone meal when the diets were compared to the basal mixed diet.

Animal Feed↗
PubMed1985

Changes in blood constituents accompanying exercise in polo horses.

There have been several studies of biochemical changes in horses doing intense exercise such as Thoroughbred and Standardbred racehorses and in horses performing exercise over a long period of time such as endurance horses and three-day eventing horses, but we are not aware of studies with polo horses. Blood samples were taken from 18 polo horses at rest, immediately after playing 2 chukkers of indoor polo, and after a 15 minute rest period. Each horse was studied at 2 different games. The blood samples were analyzed for lactic acid, protein, sodium, potassium, chloride, calcium, phosphorus, HCO-3, PCO2, hemoglobin, packed cell volume, and pH. Samples taken immediately after playing polo had significant increases in lactic acid, protein, sodium, hemoglobin, packed cell volume, and pH, and significant decreases in chloride, calcium, PCO2, and HCO-3. Pulse and respiration were significantly increased. After a 15 minute rest period, there was a significant decrease in potassium. The HCO-3 was lower immediately after playing, but was above the resting value after 15 minutes. It was concluded that the changes after exercise are similar in some aspects to those reported for horses performing intense exercise such as racehorses, and in some aspects to those reported for horses performing prolonged exercise such as three-day event horses and endurance horses. Horses playing indoor polo develop a high plasma lactic acid, but with alkalemia, and could be used as a model to study this condition.

Animals↗
PubMed1984

Some nutritional aspects of colic in horses.

Consistency of exercise and diet are important in colic prevention. Water should be offered before and after feeding. Fast-growing foals suckling heavily lactating mares may overeat grain at weaning. Creep feeding to accustom the foal to eating grain and gradually increasing the grain intake after weaning are helpful in preventing colic in foals. Stallions may overeat grain when taken off pasture in hot weather. Feeding hay initially and grain later helps avoid colic in these stallions. Type-D Clostridium perfringens may cause enterotoxemia in foals. Corn should be fed in moderation. High-Mg diets, ingestion of sand, and pelleted feed have been associated with colic. Endoparasitism is the most important cause of colic in horses.

Animal Feed↗
PubMed1983

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.

Animals↗
PubMed1983

Lactation in the horse: milk composition and intake by foals.

Milk samples averaging 500 ml were collected weekly from 10 to 54 days postpartum from five lactating mares. Samples were obtained by hand milking after oxytocin administration and while the foal nursed. Dry matter, protein and gross energy were higher in samples obtained at 10 and 17 days postpartum than those obtained during the midlactation period of 24-54 days. Midlactation samples averaged 10.5% dry matter, 1.29% fat, 1.93% protein, 6.91% sugar and 50.6 kcal/100 g. Protein comprised 22% of milk energy. Milk intake was estimated in five foals from deuterium oxide (D2O) turnover to be 16, 15 and 18 kg/day at 11, 25 and 39 days postpartum. Milk intake differed significantly among foals and at the various postpartum ages, whether intake was expressed as a daily amount, as a percent of foal body weight, per kilogram0.75 or per gram of foal body weight gain. Milk production was equivalent to 3.1% of the mare's body weight at 11 days postpartum, 2.9% at 25 days and 3.4% at 39 days. On the basis of metabolic body size milk output by the mare was 149 g/kg0.75, 139 g/kg0.75 and 163 g/kg0.75 at 11, 25 and 39 days postpartum, respectively. Nutrient intakes by foals were calculated from milk composition and intake data. At 11, 25 and 39 days postpartum, respectively, dry matter intake equaled 3.1, 2.1 and 2.0% of foal body weight, and daily gross energy intake was 9380, 7590 and 8910 kcal. For each gram of body weight gain, foals ingested 0.37 g protein and 8.3 kcal at 11 days, 0.26 g protein and 6.7 kcal at 25 days, and 0.30 g protein and 7.8 kcal at 39 days of age.

Animal Nutritional Physiological Phenomena↗
PubMed1983

Removal of the cecum, including the ileocecocolic junction, and its effects on digestibility in cattle.

The cecum and ileocecocolic junction in each of five 7-month-old Holstein steers were removed. Two steers of the same breed and age were sham-operated. All steers survived and were subjected to a digestibility experiment for 16 weeks. Digestibility of dry matter, neutral-detergent fiber, acid-detergent fiber, and cellulose decreased (P less than 0.05) during postsurgical weeks (PSW) 1 to 4, but not during PSW 16. However, digestibility of protein and hemicellulose was not significantly (P less than 0.07) influenced by the operation. Digestibility of the previously described components was not significantly different from that in 2 sham-operated steers. The mean daily weight gain of the cecectomized steers decreased during PSW 1 to 4; however, it started to increase at PSW 8 so that at PSW 16 it approached preoperative values. The mean daily weight gain of the sham-operated steers also decreased during PSW 1 to 4, but was higher than the preoperative values at PSW 14. The difference in mean daily weight gains between the cecectomized and sham-operated steers was insignificant. The consistency of the feces of the cecectomized steers was loose to watery for a period of about 4 weeks after surgery. At PSW 16, the feces were firm, but not of normal consistency. Feces of the sham-operated steers were loose after surgery, but returned to normal consistency after approximately 7 days. Adhesions developed at the surgical site and involved the ileum, the proximal loop of the ascending colon, and the adjacent mesentery and greater omentum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Morphologic and biochemical changes in cartilage of foals treated with dexamethasone.

Epiphyseal and articular cartilages were examined in pony foals treated with intramuscular injections of either 0.5 mg dexamethasone per 100 kg bodyweight daily for 3, 8 or 11 months, or 5.0 mg per 100 kg for 11 months, and in horse foals treated with 5.0 mg per 100 kg for 20 weeks. The proximal femoral growth plates exhibited increased spatial separation between chondrocyte columns, narrowed zones of disorganized columnar and hypertrophic cartilage, abnormal penetration of hypertrophic cartilage by metaphyseal capillaries, retained cartilage in the spongiosa, distal terminal plate formation, transverse trabeculation, chondronecrosis and metaphyseal osteochondrosis dissecans. Destructive articular lesions were observed after 3 months of treatment with 0.5 mg per 100 kg bodyweight. Joint damage originated either at the joint surface or deep within the cartilage. Signs of surface deterioration included edema, fibrillation, enlargement of lacunae, pitting, shredding and erosions of cartilage. Inactivity of articular cartilage growth centers was common, with failure of epiphyseal capillaries to penetrate the lacunae in the calcified cartilage. Chondronecrosis adjacent to the calcification front was accompanied by cartilage ulceration and fracture. Intracartilaginous cysts and subchondral chondroid cysts were also observed. Healing responses included reparative chondrogenesis (focal cartilage hyperplasia), formation of fibrous or fibrocartilaginous "scars," subchondral osteopetrosis and epiphyseal marrow petrosis. Lactate dehydrogenase specific activities per chondrocyte, 35S uptake per cell and glycosaminoglycan contents of articular cartilages were all reduced 55% by 3 months of treatment. This inhibition of articular chondrocyte metabolism initiated cartilage degeneration. Surface destruction and osteochondrosis dissecans followed continued mechanical stress of compromised cartilage.

Animals↗
PubMed1982

Calcium metabolism in glucocorticoid-treated pony foals.

Pony foals were injected intramuscularly with 0, 0.5, or 5.0 mg dexamethasone per 100 kg body weight daily for up to 11 months. True absorption of dietary calcium was inhibited by treatment at 18 days (57% versus 14% of intake; P less than .01) and 10 months (72% versus 55% versus 43%: P less than .01), but not at 2 or 7 months, and was independent of age and treatment related decreases in intestinal calcium binding protein activities. Uninary excretion of calcium was increased by treatment through 7 months but decreased at 10 months. Treatment for 18 days resulted in total calcium excretions equivalent to 127% of dietary intake. All animals were in positive calcium balance thereafter. Endogenous fecal calcium excretion was not affected by treatment, age, or sex, averaging 18.0 mg per kg body weight per day. At 2 months, rates of calcium deposition into bone were 13.02, 7.01 and 6.83 g per 100 kg per day in ponies treated with 0, 0.5 and 5.0 mg per 100 kg, respectively. Corresponding rates of calcium removal from bone were 5.41, 1.88, and 2.69 g per 100 kg per day. These rates remained significantly inhibited in the treated ponies at 7 and 10 months. The net effect of dexamethasone treatment was an inhibition of bone turnover: calcium removal was suppressed more than inhibition of bone turnover: calcium removal was suppressed more than calcium deposition.

Absorption↗
PubMed1982

Utilization of bamboo by the giant panda.

Two giant pandas were used to assess the utilization of bamboo as a feedstuff. Three 1-week-long digestion trials were conducted during which feed intake and fecal output were recorded. Passage of digesta was measured from both fluid and particulate markers administered at feeding. Results indicate that the giant panda, although highly specialized for the consumption of bamboo, is a very inefficient digester of bamboo. The pandas consumed up to 6% of body weight in dry matter per day, with bamboo dry matter digestibility averaging less than 20%. Apparent digestion coefficients for the structural carbohydrates of bamboo (27% for hemicellulose and 8% for cellulose) indicate that, unlike most herbivores, pandas do not rely heavily on the microbial degradation of plant material to fulfill their nutritional requirements. Additionally, the passage of digesta through the gastrointestinal tract of the panda was extremely rapid, with complete clearance of markers in less than 12 hours. The giant panda seems to have specialized to a feed source high in plant fiber without extensive modification of the digestive tract by selectivity in feeding, effective mastication, ingestion of large quantities, digestion of cellular contents rather than cell walls and rapid fecal excretion of the undigested residue.

Animal Nutritional Physiological Phenomena↗
PubMed1982

Learning ability of orphan foals, of normal foals and of their mothers.

The maze learning ability of six pony foals that had been weaned at birth was compared to that of six foals reared normally. The foals' learning ability was also compared to their mothers' learning ability at the same task; the correct turn in a single choice point maze. The maze learning test was conducted when the foals were 6 to 8 mo old and after the mothered foals had been weaned. There was no significant difference between the ability of orphaned (weaned at birth) and mothered foals in their ability to learn to turn left (6 +/- .7 and 5.1 +/- .1 trials, respectively) or to learn the reversal, to turn right (6.7 +/- .6 and 6.2 +/- .6 trials, respectively). The orphan foals spent significantly more time in the maze in their first exposure to it than the mothered foals (184 +/- 42 vs 55 +/- 15 s. Mann Whitney U = 7, P less than .05). The mothers of the foals (n = 11) learned to turn left as rapidly as the foals (5.9 +/- .7 trials), but they were slower to learn to turn right (9.8 +/- 1.4 vs 6.4 +/- .4 trials, Mann Whitney U = 33, P less than .05), indicating that the younger horses learned more rapidly. There was no correlation between the trials to criteria of the mare and those of her foal, but there was a significant negative correlation between rank in trials to criteria and age (r = -65, P less than .05) when data from the mare and foal trials were combined. The dominance hierarchy of the mares was determined using a paired feeding test in which two horses competed for one bucket of feed. Although there was no correlation between rank in the hierarchy and maze learning ability, there was a correlation between body weight and rank in the hierarchy (r = .7, P less than .05). This may indicate either that heavier horses are likely to be dominant or that horses high in dominance gain more weight. Maternal deprivation did not appear to seriously retard learning of a simple maze by foals, although the orphans moved more slowly initially. The lack of maternal influence on learning is also reflected in the lack of correlation between the mare's learning ability and that of her foal. Young horses appear to learn more rapidly than older horses.

Age Factors↗