Biomedical subjects

S L Ralston

Publications and source records attributed to S L Ralston.

At least 19 recordsLinked to original sources

PubMed2001

Effect of dental correction on feed digestibility in horses.

To test the hypothesis that routine dental correction (removal only of sharp hooks and points from molars and premolars) would improve digestion of a hay/grain ration whereas performance 'floats' (rounding and smoothing of the dental arcades) would adversely affect digestion, 8 mature horses free from dental correction for over a year were used. Five-day digestion trials were conducted before and 2 and 4 weeks after correction in all horses. Although all horses had sharp points and minor premolar hooks, none had severe dental abnormalities. There were no significant differences found in apparent digestion of dry matter, crude protein, neutral detergent fibre or acid detergent fibre relative to precorrection data or controls (uncorrected horses on same digestion trial). Apparent digestibility of crude protein and fibre, however, was reduced if the occlusal angle of premolar 307 was greater than 80 degrees relative to the vertical axis (flattened). It should be recommended that regular dental correction be continued. However, if only small points and hooks are present, correction will not significantly improve digestion. Performance floating does not adversely affect digestion 2-4 weeks after the procedure is performed. Alterations in molar occlusal surface angle may affect digestibility of protein and fibre.

Animal Feed↗

PubMed1999

Diurnal variation and age differences in the biochemical markers of bone turnover in horses.

Biochemical markers of bone turnover provide sensitive, rapid, and noninvasive monitoring of bone resorption and formation. Serum concentrations of osteocalcin (OC) reflect rates of bone formation, and urinary concentrations of the pyridinium crosslinks pyridinoline (Pyd) and deoxypyridinoline (Dpd) are specific and sensitive markers of bone resorption. These markers are age-dependent and are used to detect and monitor changes in the rates of bone turnover in a variety of orthopedic diseases in humans and may prove to have similar application in horses. This study examined age differences and diurnal variation in OC, Pyd, and Dpd in eight adult geldings and seven weanling colts. Blood and urine were collected at regular intervals over 24 h. Serum OC and cortisol, and urinary Pyd and Dpd were analyzed. Mean 24-h concentrations of cortisol and all three markers were higher (P<.003) in weanlings than adults. Significant 24-h variation was observed in adult gelding OC, Pyd, and Dpd concentrations (P< .02). Adult OC concentrations were highest between 2400 and 0900; Pyd and Dpd peaked between 0200 and 0800. Similar patterns of bone turnover were observed in weanling values, but they were not significant (P>.17) owing to greater variability between individuals. Cortisol secretion varied (P<.001) over 24 h in both adults and weanlings and, thus, did not seem to be responsible for greater variability in markers of bone turnover between weanlings. These data demonstrate that diurnal rhythms exist for serum OC and urinary Pyd and Dpd in adult horses, as reported in humans, and that sample timing is an important consideration in future equine studies using these markers.

Aging↗

PubMed1997

Stereoselective activation of dibenzo[a,l]pyrene and its trans-11,12-dihydrodiol to fjord region 11,12-diol 13,14-epoxides in a human mammary carcinoma MCF-7 cell-mediated V79 cell mutation assay.

Dibenzo[a,l]pyrene (DB[a,l]P) represents the most potent carcinogenic polycyclic aromatic hydrocarbon (PAH) yet discovered. Like other PAHs, DB[a,l]P requires metabolic activation to exert its mutagenic and/or carcinogenic activity. In the human mammary carcinoma cell line MCF-7, DB[a,l]P is stereoselectively metabolized to the (-)-anti- and (+)-syn-DB[a,l]P-11,12-diol 13,14-epoxides (DB[a,l]PDE) which both bind extensively to deoxyadenosine residues in DNA. To further characterize the underlying mechanism of its strong carcinogenicity, the relationship between DNA binding and mutagenicity of DB[a,l]P was determined. Racemic DB[a,l]P-11,12-dihydrodiol and the two individual (+)- and (-)-enantiomers, the metabolic precursors of the stereoisomeric fjord region dihydrodiol epoxides, were also investigated. Induction of mutations at the HPRT locus was measured in a MCF-7 cell-mediated Chinese hamster V79 cell mutation assay. The parent hydrocarbon, (+/-)-DB[a,l]P-11,12-dihydrodiol, and (-)-DB[a,l]P-11,12-dihydrodiol were highly mutagenic under the assay conditions. In contrast, (+)-DB[a,l]P-(11S,12S)-dihydrodiol was not mutagenic using MCF-7 cells as the metabolic activating system. Analysis of DNA adducts in the same experiments revealed that MCF-7 cells treated with (-)-DB[a,l]P-11,12-dihydrodiol formed exclusively (-)-anti-DB[a,l]-PDE adducts whereas cells treated with (+)-DB[a,l]P-11,12-dihydrodiol did not contain detectable levels of DNA adducts. These results suggest that specific cytochrome P450 enzymes may have high stereoselectivity for activation of the two DB[a,l]P-11,12-dihydrodiol enantiomers, and this may play an important role in the metabolic activation of the strong carcinogen DB[a,l]P in human cells.

Animals↗

PubMed1995

Stereoselective activation of dibenzo[a,l]pyrene to (-)-anti (11R,12S,13S,14R)- and (+)-syn(11S,12R,13S,14R)-11,12-diol-13,14-epoxides which bind extensively to deoxyadenosine residues of DNA in the human mammary carcinoma cell line MCF-7.

Dibenzo[a,l]pyrene (DB[a,l]P) is an environmental contaminant and a very potent carcinogen. DB[a,l]P exceeds the carcinogenic potency of both benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene in rodent bioassays. Previous studies demonstrated that DB[a,l]P is metabolized to DB[a,l]P-11,12-diol-13,14-epoxide (DB[a,l]PDE) in the human mammary carcinoma cell line MCF-7. In the present study the major DNA adducts formed in DB[a,l]P-treated MCF-7 cells have been identified through the use of 33P-postlabeling. TLC and HPLC. DB[a,l]P is metabolically activated in MCF-7 cells to form large amounts of three major DNA adducts and smaller amounts of three other adducts. The three major DNA adducts are with deoxyadenosine: two are formed by reaction of (+)-syn-DB[a,l]PDE (11S,12R,13S,14R), the third by reaction of (-)-anti-DB[a,l]PDE (11R,12S,13S,14R). The results demonstrate that DB[a,l] is stereoselectively metabolized in MCF-7 cells to form one enantiomer of each diol epoxide diastereomer; (+)-syn-DB[a,l]PDE and (-)-anti-DB[a,l]PDE. The high extent of binding of these diol epoxides to deoxyadenosine in DNA of MCF-7 cells may help to explain the very high carcinogenic potency of DB[a,l]P and suggests that DB[a,l]P could also pose a carcinogenic threat to humans.

Benzopyrenes↗

PubMed1995

Effects of shortening the steeplechase phase (phase B) of a 3-day-event.

Thirty-four horses competing in the Endurance Test of a 3-day-event were divided into 3 groups: horses in Group 1 (n = 15) competing in a 3.5 min steeplechase phase; horses in Group 2 (n = 13) in a 3 min steeplechase phase (Phase B) and horses in Group 3 (n = 6) in a 2.5 min steeplechase phase. The shortening of Phase B was associated with a lengthening of Phase C so that the total distance of the event for all horses was 14,940 m. Bodyweight (BW) was measured and total body water (TBW) and water loss estimated. Blood samples were collected from the horses prior to the Endurance Test, at the end of Phase B, the 4 km marker on Phase C (C4K), the end of Phase C, and 20 min after the completion of Phase D for measurement of packed cell volume (PCV), total plasma protein [TPP], lactate, ionised calcium, pH, sodium, potassium, chloride, total calcium and glucose concentrations, and aspartate aminotransferase, creatine kinase and lactate dehydrogenase activities. Mean +/- s.d. ambient environmental temperature during the Endurance Test was 25.3 +/- 1 degrees C (range 20.3 degrees C-29.7 degrees C). Mean relative humidity was 43.8 +/- 2.4% (range 39%-48.6%) and the average 'comfort index' (CI) was 121. There were no significant differences between the groups competing in the Endurance Test, despite the shorter Phase B. However, there were significant decreases in BW, TBW, net exchangeable cations, chloride, ionised calcium, and pH. The sodium and total calcium concentrations remained at near pre-event values. The PCV, TPP, lactate, potassium, glucose, aspartate aminotransferase, and lactate dehydrogenase activity increased during the Endurance Test, when compared to pre-event values. Horses competing in this competition experienced significant fluid and electrolyte losses, reduced glomerular filtration, increased glycogenolysis and had significant leakage of enzymes from working muscles during competition. These changes could not be reduced by shortening Phase B and lengthening Phase C.

Animals↗

PubMed1994

Weight, water, and cation losses in horses competing in a three-day event.

Body weight of 48 horses competing in a 3-day event was measured the day before the event (baseline), following the dressage phase of the event (day 1), after the endurance phases of the event (day 2), and 18 to 24 hours after the endurance phases (day 3). Plasma sodium and potassium concentrations were measured the evening before, immediately after, and 10 minutes after the endurance phases. Total body water, water loss, and net exchangeable cation loss were then calculated. Body weight and total body water were significantly decreased, compared with baseline values, at all times during the event, and significant water loss was detected. The largest changes were recorded after the endurance phases of the event. Water deficits were still detected 18 to 24 hours after the endurance phases of the event. Mean plasma sodium concentration was significantly increased immediately after the endurance phases of the event, compared with concentration measured the evening before, and remained increased after the 10-minute recovery period, presumably because of dehydration. Mean plasma potassium concentration was significantly increased immediately after the endurance phases of the event, compared with concentration measured the evening before, but was not increased after the 10-minute recovery period.

Animals↗

PubMed1994

The potent carcinogen dibenzo[a,l]pyrene is metabolically activated to fjord-region 11,12-diol 13,14-epoxides in human mammary carcinoma MCF-7 cell cultures.

Dibenzo[a,l]pyrene (DB[a,l]P), an environmental hydrocarbon and very potent carcinogen in rodent bioassays, could be activated to DNA-binding intermediates in cells through formation of three different regioisomeric bay- or fjord-region diol-epoxides or other more highly oxidized metabolites. The mechanism of metabolic activation of DB[a,l]P in the human mammary carcinoma cell line MCF-7 was elucidated by analyzing the DB[a,l]P-DNA adducts formed by [35S]phosphorothioate postlabeling, immobilized boronate chromatography, and high-performance liquid chromatography. Six DB[a,l]P-DNA adducts were detected. Comparison with those formed in cells by DB[a,l]P-11,12-diol and by reaction of DNA with syn- and anti-(benzylic hydroxyl and epoxide oxygen cis and trans, respectively) DB[a,l]P-11,12-diol-13,14-epoxide (DB[a,l]PDE) demonstrated that all DB[a,l]P-DNA adducts in MCF-7 cells were formed by these diol-epoxide isomers. Cellular DNA contained large amounts of two syn- and one anti-DB[a,l]PDE-DNA adducts and small amounts of one syn- and two anti-DB[a,l]PDE-DNA adducts. The ability of human cells to activate DB-[a,l]P to its fjord-region 11,12-diol 13,14-epoxides suggests that environmental exposure to DB[a,l]P could pose a risk for humans.

Benzopyrenes↗

PubMed1993

Serum chemistry and lipid profiles in neonatal beagle puppies fed homemade milk replacer formulas.

Milk replacer formulas based on cow's milk and egg yolks are frequently recommended for use in neonatal puppies. These formulas are lower in protein, kilocalories, calcium, and phosphorus than bitch's milk. In addition, the cholesterol content is greater than bitch's milk. The effect of feeding these formulas on serum chemistry profiles, lipid profiles, and alkaline phosphatase isoenzyme profiles of 5-week-old beagle puppies was studied. Three groups of beagle puppies were fed bitch's milk (control) (n = 18), a homemade milk-egg-oil formula (Formula 1) (n = 18), or a homemade milk-egg-oil formula supplemented with additional calcium and phosphorous (Formula 2) (n = 18). Concentrations of serum urea nitrogen, albumin, and total CO2 were lower (P < 0.05), and concentrations of serum phosphorus, globulins, sodium, chloride, and cholesterol were higher (P < 0.05) in formula-fed puppies than bitch-fed puppies. Serum potassium concentration was lower in the puppies fed Formula 1 than in the control puppies (P < 0.05), and serum potassium concentration in the puppies fed Formula 2 was not significantly different from that in puppies fed Formula 1 or the control puppies. Total triglyceride (TG) and high density lipoprotein2 cholesterol (HDL2) concentrations were similar in all three groups of puppies but the combined high density lipoprotein1 (HDL1) plus low density lipoprotein (LDL) cholesterol fraction was higher (P < 0.05) in the formula-fed puppies and accounted for the majority of the increase in cholesterol. There were no differences (P < 0.05) in total serum alkaline phosphatase (ALP) or bone-derived ALP (BALP) concentrations among the groups, however there was a higher (P < 0.05) serum concentration of liver-derived ALP (LALP) in the Formula 1-fed puppies. Feeding homemade egg and cow's milk-based puppy replacement formulas is not recommended for long term use.

Alkaline Phosphatase↗

PubMed1990

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.

Animal Nutritional Physiological Phenomena↗

PubMed1990

Effects of transportation on early embryonic death in mares.

Incidence of early embryonic death (EED) and associated changes in serum cortisol, progesterone and plasma ascorbic acid (AA) in transported mares were investigated. Mares were transported for 472 km (9 h) during either d 16 to 22 (T-3 wk, n = 15) or d 32 to 38 (T-5 wk, n = 15) of gestation. Blood samples were drawn from control, nontransported mares (NT-3 wk, NT-5 wk, n = 24) and transported mares pre-trip, midtrip, and at 0, 12, 24, 48 and 72 h post-transport and daily for the next 2 wk. Incidence of EED between transported and nontransported mares was not different (P greater than .05). Serum cortisol in all transported mares increased (P less than .05) relative to pre-trip values at midtrip and 0 h post-transport. Relative to NT mares, serum cortisol was higher (P less than .05) at midtrip in T-3 wk mares and 0 h post-transport in T-5 wk mares. Serum progesterone in all T mares increased (P less than .05) at midtrip relative to pre-trip values and was higher (P less than .05) in T-3 wk mares than in NT-3 wk mares at midtrip and 0 h post-transport. Post-transport decreases (P less than .05) in concentrations of progesterone were observed in mares that aborted. Plasma AA in transported mares increased (P less than .05) at midtrip in T-5 wk mares and decreased (P less than .05) relative to pre-trip values at 24 and 48 h post-transport (T-3 wk and T-5 wk mares, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Effect of transportation on the estrous cycle and concentrations of hormones in mares.

Effect of transportation on estrous behavior, duration of the estrous cycle, ovulation, pregnancy rates and concentrations of serum cortisol, plasma ascorbic acid (AA), LH, estradiol and progesterone in mares was investigated. Fifteen mares were transported for 792 km (12 h) during the preovulatory stage of estrus. Transported mares were bled immediately before transport (baseline), at midtrip and 0, 12, 24, 48 and 72 h post-transport and twice daily from d 1 before transport to d 1 (estrogen) or 3 (LH) post-ovulation. Blood samples also were taken for progesterone on d 0, 2, 6, 10, 15, 16, 17, 18, 19 and 20 post-ovulation. Nontransported control mares (n = 15) were bled on the same schedule as transported mares. There was no difference (P greater than .05) in number of mares ovulating, estrous behavior, duration of the estrous cycle or pregnancy rate between groups. Cortisol in transported mares increased to concentrations greater (P less than .05) than those in control mares at midtrip and 0 h post-transport. Concentrations of AA in transported mares also increased (P less than .05) at midtrip, then decreased (P less than .05) below baseline at 24 h post-transport. Concentrations of LH and estradiol increased (P less than .05) above baseline throughout the blood-sampling period. Increases apparently were due to preovulatory surges of these hormones. Increase in LH concentrations in transported mares, however, was greater (P less than .05) than that in control mares at 0 h post-transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Fiber digestion and voluntary intake in horses after adaptation to extensive large-colon resection.

Each of 3 digestion trials (3 forage diets) was performed on 2 groups of horses 6 to 12 months after sham operation (group 1; n = 3) or large-colon resection (group 2; n = 5). Diets were alfalfa pellets, alfalfa hay, and grass hay. Feed and fecal analyses were performed to determine apparent digestion of dry matter, organic matter, and crude protein and true digestion of dry matter, organic matter, crude protein, total plant cell wall, hemicellulose, cellulose, and lignin. Additional fecal and metabolic variables determined were percentage of fecal water, total fecal water, metabolic organic matter, metabolic crude protein, and metabolic nitrogen. Large-colon resection decreased the digestion of plant cell wall because of decreased digestion of cellulose in alfalfa pellet and grass hay diets, but not in alfalfa hay diet. Insufficient digestible energy and/or protein from grass hay was obtained by horses with colon resection, and significant (P less than 0.05) weight loss was observed. Voluntary intake was significantly (P less than 0.05) increased by horses with colon resection. Of the diets studied, alfalfa hay was the most appropriate forage diet, compared with average grass hay and alfalfa pellet diet, for horses after extensive large-colon resection. Additionally, horses with colon resection may have higher levels of feed intake than do horses without colon resection.

Adaptation, Physiological↗

PubMed1989

Large intestinal capacity, retention times, and turnover rates of particulate ingesta associated with extensive large-colon resection in horses.

Fecal excretion of a particulate marker, ytterbium (Yb), was evaluated in 9 horses before surgery and 3 weeks, 3 months, and 6 months (4 trials) after sham-operation (group 1; n = 3) or extensive large colon resection (group 2; n = 6). Fecal excretion curves of total Yb excretion, loge Yb excretion, % Yb excretion, loge % Yb excretion, and cumulative % Yb excretion were evaluated, and kinetic analysis was performed on the loge Yb excretion curves to detect mixing pools and to calculate the fractional rate of particulate passage, turnover rate, and pool size. Calculations were performed to determined transit time, mean overall retention time, adjusted mean retention time, peak time, and disappearance time. Values were statistically analyzed to determine differences between groups and among trials (P less than 0.05). Group-2 horses had significantly shorter transit, peak, and mean overall retention times, compared with preoperative values and with values for group-1 horses. Two mixing pools were identified: a slower emptying pool of 5.7% hour-1 (k1) and a faster emptying pool of 12.3% hour-1 (k2). The rate of passage from the first pool (k1) was not altered by colon resection, and was interpreted as being most influenced by the cecum. In further support of this interpretation, the capacity of the k1 pool approximated the capacity of the cecum (17 L). The capacity of the k1 pool significantly expanded by 6 months in the resected horses. the rate of passage from the second pool (k2) significantly increased initially after colon resection (3 weeks and 3 months), but returned to preoperative values by 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Differences in diagnostic test results and hematologic data between aged and young horses.

Hematologic data and results of diagnostic tests were compared between aged (greater than or equal to 20 years old) and young (less than or equal to 5 years old) horses to identify hematologic and metabolic changes associated with aging. Initial data were obtained from 8 aged and 6 young mares (group 1). Similar data were collected from a second group of aged (3 mares and 3 geldings) and young (1 mare and 5 geldings) horses (group 2). Dexamethasone suppression tests (DST) and necropsies were performed on 6 additional mares and mare 8 from group 1 (group 3). Complete blood counts and serum biochemical profiles were compared between young and aged horses of groups 1 and 2. Mean corpuscular volume was higher (P less than 0.05) in aged horses. Oral glucose tolerance and insulin response to orally administered glucose were measured in 13 aged horses (groups 1 and 2) and 6 young mares of group 1. In group 1, plasma ascorbic acid values were lower (P less than 0.05) in aged horses than in young horses maintained under the same conditions and feeding regimens. An apparent age-related hyperinsulinemic response to orally administered glucose identified in group-1 mares was probably a result of a high occurrence of subclinical hypophyseal and/or thyroid adenomas. Of 13 aged horses necropsied (groups 2 and 3), 10 had hypophyseal and/or thyroid adenomas that, in group 2, were consistently associated (P less than 0.05) with hyperinsulinemic responses to orally administered glucose. All horses in groups 2 and 3 were given a 24-hour DST.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1988

Nutritional management of horses competing in 160 km races.

A survey was taken of dietary management and training schedules of 54 horses competing in two 160 km endurance races. A total of 52 owners, representing 54 horses, responded to a questionnaire distributed prior to the races. Diet and training schedules were compared between horses that successfully completed the races and those that were eliminated for metabolic reasons. Horses that completed the races were 11.5 +/- 4 years old, weighed 429 +/- 4.5 kg and were ridden 61 +/- 32 km a week when training. Feed intake was reported as "free choice hay or pasture" by 34 of the respondents. Dry matter (DM) hay intake in these horses was estimated to be 3% body weight (kg) minus the kg DM of grain fed, assuming a maximum intake. They were fed 12.3 +/- 2.3 kg feed per day consisting of 10 +/- 2.3 kg hay and 2.3 +/- 1.4 kg of grain. Most had free access to salt and were fed 1 +/- 1 vitamin/mineral supplement per day. Based on Nutritional Research Council (NRC) values for nutrient content of the reported feeds, diets contained 60 +/- 5% total digestible nutrients (TDN), 12 +/- 2% crude protein, 27 +/- 4% crude fiber, 0.72 +/- 0.4% calcium and 0.29 +/- 0.06% phosphorus. Maximum caloric intake was estimated to be 31.9 Mcal per day. Ratios of nutrients fed per kilometer trained were: kg TDN/km = .14 +/- .08, kg crude protein/km trained = .03 +/- .02, and kg crude fiber/km trained = .06 +/- .04.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗

PubMed1986

Feeding behavior.

Problems related to feeding behavior in horses fall into three main categories: underconsumption, overconsumption, and abnormal consumption. Anorexia may be caused by a variety of diseases and overcome by removing the underlying causes (pain, fever), and physical or chemical stimulation of appetite. "Hypophagia" may be caused by poor dentition, disease, or stress. Again, removal of the cause or stimulation by physical or chemical means may improve intakes. Acute and chronic overconsumption of feeds are reflections of the normal controls (or lack thereof) of feeding in the horse. The only reliable prevention is to limit access to feeds. Abnormal eating behaviors such as pica or coprophagy are usually caused by a dietary imbalance or boredom. Coprophagey, however, is a normal behavior in young foals. Drinking disorders are rare, the only common one being the avoidance of "strange" water. Masking water at home with specific flavors such as peppermint or vinegar may encourage the horse to drink water from other sources to which the "home" flavor has been added.

Animals↗

PubMed1986

Digestion in horses after resection or ischemic insult of the large colon.

The effect of 60% resection of the large colon vs ischemic insult without resection on the ability of horses to digest grass hay was investigated. Digestion trials were performed on 9 horses before surgery (base line) and 3 weeks, 6 weeks, and 6 months after surgery. The percentage of apparent digestion of crude protein, crude fiber, nitrogen-free extract, calcium, phosphorus, magnesium, manganese, copper, and zinc was calculated. Horses that had resection (n = 5) had decreased apparent digestion of crude protein, crude fiber, and phosphorus 3 weeks after surgery, compared with those in horses with ischemic insults (n = 4) and with base-line values. Horses with ischemic insults also had a decrease in crude protein digestion 3 weeks after surgery, compared with base-line values. All horses returned to base-line values of digestion at the 6-month trials, although horses that had resection had higher fecal concentrations of phosphorus and nitrogen-free extract than did horses with ischemic insult. During the study, all horses had maintained good body condition.

Animals↗

PubMed1984

Controls of feeding in horses.

Members of the genus Equus are large, nonruminant herbivores. These animals utilize the products of both enzymatic digestion in the small intestine and bacterial fermentation (volatile fatty acids) in the cecum and large colon as sources of metabolizable energy. Equine animals rely primarily upon oropharyngeal and external stimuli to control the size and duration of an isolated meal. Meal frequency, however, is regulated by stimuli generated by the presence and (or) absorption of nutrients (sugars, fatty acids, protein) in both the large and small intestine plus metabolic cues reflecting body energy stores. The control of feeding in this species reflects its evolutionary development in an environment which selected for consumption of small, frequent meals of a variety of forages.

Animal Feed↗