Journal of animal science.
Publisher:
American Society of Animal Science
Frequency: Monthly,
Country: United States
Language: English
Author(s):
American Society of Animal Science., American Society of Animal Production.
Start Year:1942 -
ISSN:
0021-8812 (Print)
1525-3163 (Electronic)
0021-8812 (Linking)
1525-3163 (Electronic)
0021-8812 (Linking)
Impact Factor
3.3
| NLM ID: | 8003002 |
| (DNLM): | J12580000(s) |
| (OCoLC): | 01782370 |
| Coden: | JANSAG |
| Classification: | W1 JO536H |
The effects of bovine somatotropin (bST) and porcine somatotropin (pST) on growth factor and metabolic variables in horses. Effects of exogenous pST and bST on metabolic and growth factor variables were examined in three studies with lighthorse mares (455 to 545 kg). In Study 1, eight mares received five s.c. injections of bST or pST (30 mg/d). In Studies 2 and 3, five mares received one s.c. injection of a prolonged release formulation designed to deliver 500 mg of bST (Study 2) or pST (Study 3) over 14 d. Blood samples were collected for several days before injection to establish baseline values, at frequent intervals during treatment, and for several days thereafter. In all studies, blood urea nitrogen concentra...
Calcium decreases and parathyroid hormone increases in serum of periparturient mares. Changes in serum concentrations of Ca and parathyroid hormone (PTH) may develop in periparturient mares, may be influenced by dietary Ca, and may be associated with changes in Ca concentration of mammary secretion. Milk and blood samples were taken from eight mares on Farm A and eight on Farm B for 10 d before parturition and from four mares on each farm for 5 d postpartum. Milk Ca was measured by two commercial tests. Serum samples were analyzed for PTH and total Ca in 16 mares and for ionized Ca in six (Farm A). Parturition was induced in eight mares on Farm A and four on Farm B; no signific...
Feed deprivation of mares: plasma metabolite and hormonal concentrations and responses to exercise. Twelve light horse mares were fed a control diet that provided 100% of their maintenance protein and energy requirements for 7 d and were then either continued on the control diet or totally deprived of feed (with access to water) for 3 d . Plasma samples were drawn twice daily throughout the experiment, at 15-min intervals for 9 h beginning 45 h after feed removal, and at 10-min intervals around an exercise bout beginning 73 h after feed removal. Feed deprivation increased (P < or = .06) whole blood beta-hydroxybutyrate and plasma NEFA, urea N, L-lactate, and glucagon concentrations, decrease...
Preweaning diet and stall weaning method influences on stress response in foals. The stress response of foals during weaning was examined in terms of a behavioral protocol and the responses of plasma ascorbate, serum cortisol, and the serum cortisol response to an ACTH challenge. The experimental plan was a 2 x 2 factorial of two preweaning diets and two stall weaning methods. Dietary groups included foals raised on pasture supplemented with hay and a pelleted concentrate (PHC) and foals raised on pasture supplemented with hay only (PH). Stall weaning methods included foals placed in stalls singly or in pairs. Sex influences were also examined. The foals exhibited characte...
Skeletal growth rates of weanling and yearling thoroughbred horses. This study was conducted to determine normal rates of growth of different skeletal segments in the thoroughbred horse. Growth of body weight and eight skeletal segments (wither height, hip height, body length, knee to pastern length, hock to pastern length, shoulder to pastern length, width of chest, depth of girth) were monitored in 106 horses (60 colts, 46 fillies) during the period from 14 to 588 d of age. Body weight gains were slightly higher (30 to 40 kg) than previously reported values. Growth in wither height and hip height were similar to previous reports. During the period measured i...
Acid-base variables during incremental exercise in sprint-trained horses fed a high-fat diet. Seven Arabian horses performed a standard incremental exercise test on a high-speed treadmill at 6% slope then were randomly assigned to two diets, a control diet of ground hay and concentrates and a similar diet with 10% added fat (by weight). Horses were sprint-trained 4 d/wk, and two additional exercise tests were performed at 5-wk intervals. Heart rates and rectal temperatures were monitored and venous blood samples were collected at rest and at each speed increment. Whole blood was analyzed for glucose, lactate, and hemoglobin concentrations, and plasma was analyzed for pH, pCO2, albumin,...
Dietary protein and(or) energy restriction in mares: plasma growth hormone, IGF-I, prolactin, cortisol, and thyroid hormone responses to feeding, glucose, and epinephrine. Sixteen light horse mares were fed diets of bermudagrass hay and a corn/cottonseed hull-based supplement formulated to contain either 100% (control) or 50% (restricted) of the protein and(or) energy requirements for maintenance in a 2 x 2 factorial arrangement of treatments. Plasma IGF-I, prolactin, cortisol, triiodothyronine, and thyroxine were monitored for 33 d. On the 27th d, frequent blood samples were drawn throughout the day for the measurement of growth hormone (GH), and on the 29th d, an epinephrine challenge and an i.v. glucose tolerance test (IVGTT) were performed in the morning and...
Endogenous toxins and mycotoxins in forage grasses and their effects on livestock. Plant toxins are the chemical defenses of plants against herbivory. Grasses have relatively few intrinsic toxins, relying more on growth habit to survive defoliation and endophytic fungal toxins as chemical defenses. Forage grasses that contain intrinsic toxins include Phalaris spp. (tryptamine and carboline alkaloids), sorghums (cyanogenic glycosides), and tropical grasses containing oxalates and saponins. Toxic effects of these grasses include neurological damage (Phalaris staggers), hypoxia (sudangrass), saponin-induced photosensitization (Brachiaria and Panicum spp.), and bone demineraliza...
Acremonium in fescue and ryegrass: boon or bane? A review. Acremonium coenophialum Morgan-Jones and Gams, an endophytic fungus commonly found in tall fescue (Festuca arundinacea Schreb.), has been identified as the cause of poor performance of beef cattle and horses on tall fescue. Ryegrass staggers, a neurological disorder of sheep, has been linked to the presence of a similar fungus, A. lolii Latch, Christensen and Samuels, in perennial ryegrass (Lolium perenne L.). Renovation of endophyte-infected (E+) pastures with endophyte-free (E-) cultivars of tall fescue or perennial ryegrass has resulted in improved animal performance, but productivity and s...
Equine fescue toxicosis: signs and solutions. Gravid mares grazing endophyte-infested (E+) tall fescue exhibit increased gestation lengths, agalactia, foal and mare mortality, tough and thickened placentas, weak and dysmature foals, increased sweating during warm weather, reduced serum prolactin and progesterone, and increased serum estradiol-17 beta levels. Also, E+ tall fescue hay is less digestible than endophyte-free (E-) hay. Unlike many other species, horses consuming E+ tall fescue do not exhibit increased body temperature. Young horses consuming only E+ pasture do not gain as well as those consuming E- pasture. There is little dif...
Trace mineral supplementation of yearling horses. Thirty-three Thoroughbred and Quarter Horse yearlings were used in two experiments (18 in Exp. 1 and 15 in Exp. 2) to determine the influence of trace mineral (TM) supplementation on growth and bone mineral content in young growing horses from 340 to 452 d of age. In each experiment the yearlings were assigned at random within breed and sex outcome groups to one of three treatments. Horses were fed assigned concentrates individually to appetite for two 1.5-h feeding periods, daily and group-fed Coastal bermudagrass (Cynodon dactylon) hay in drylot paddocks at a rate of 1.0 kg/100 kg BW daily. ...
Dietary protein and(or) energy restriction in mares: plasma glucose, insulin, nonesterified fatty acid, and urea nitrogen responses to feeding, glucose, and epinephrine. Sixteen light horse mares (8 to 9 yr of age; 457 to 579 kg BW) were fed Bermudagrass hay and a corn/cottonseed hull-based supplement formulated to contain either 100% (control) or 50% (restricted) of the protein and(or) energy requirements for maintenance in a 2 x 2 factorial arrangement of treatments. Daily measurements of intake, BW, and plasma hormones and metabolites were made for 33 d. Plasma glucose, insulin, NEFA, and urea N were measured in hourly samples drawn on d 27, and parallel with an i.v. glucose tolerance test (IVGTT) and epinephrine challenge on d 29. Energy restriction increa...
Discrimination learning and concept formation in the Arabian horse. Discrimination learning and concept formation abilities were investigated in four mature Arabian horses. A series of two-choice discrimination problems were presented on stimulus panels that could open to allow access to food bowls. Selection of the correct stimulus resulted in food reinforcement, and an incorrect choice was not rewarded. The positions of the correct and incorrect stimuli were varied randomly during each test session, and the criterion for learning each problem was 85% correct for two consecutive sessions of 30 or 40 trials. Testing progressed through six discrimination proble...
Growth hormone and prolactin concentrations in plasma of horses: sex differences and the effects of acute exercise and administration of growth hormone-releasing hormone. Three experiments were conducted to determine 1) the relationship between prolactin and growth hormone (GH) secretion in mares and the response to GH-releasing hormone (GHRH), 2) whether plasma GH and prolactin concentrations differed among mares, stallions, and geldings, and 3) whether sexual differences existed after administration of GHRH and acute exercise. In Exp. 1, 10-min blood samples were collected from 12 mares for 8 h, and GHRH (0, 45, 90, or 180 micrograms) was administered at 6 h. In Exp. 2, 15-min blood samples were collected for 4 h from 10 mares, stallions, and geldings. In Exp...
The mechanical properties of equine third metacarpals as affected by age. Twenty-five pairs of equine third metacarpals (McIII) were collected from horses of varying breeds and ranging in age from 1 d to 27 yr. Standard three-point bending tests were performed on the McIII to obtain comparative data on breaking load (BL), breaking strength (BS), and elasticity (E). Broken bones were reassembled and 2-cm sections cut from the bone 1 cm below the nutrient foramen and at the site of the break. Bone mineral content (BMC) and geometrical properties of these sections were determined. Maximum BMC (17.3 g/2 cm) was reached at 6.0 +/- 1.8 yr of age. Horses in this study achi...
Plasma concentrations of prolactin, glucose, insulin, urea nitrogen, and total amino acids in stallions after ingestion of feed or gastric administration of feed components. Concentrations of prolactin, glucose, insulin, urea N, and total amino acids in plasma of stallions after ingestion of pelleted feed were compared to those after direct gastric administration of water, NaCl, egg albumin, or corn starch (Exp. 1) or water, egg albumin, hydrolyzed casein (Amicase), or a mixture of indispensable amino acids (Exp. 2). Stallions were fed once daily (75% pellet and 25% hay) at 1500 for 30 d. On d 22, 24, 26, 28, and 30, blood samples were collected every 30 min from 1 h before through 4 h after treatment, which occurred at 1100. In Exp. 1, there was a positive secret...
Maternal influences on growth and development of full-sibling foals. Six pairs of full-sibling Quarter Horse foals were produced by non-surgical embryo transfer and immediate rebreeding of donor mares. Each pair of donor/recipient mares consisted of one multiparous (donor) and one nulliparous (recipient) mare of similar body type and size. Milk yield was determined within 2 d of 8, 15, 22, 29 d (early lactation); 45, 60 d (midlactation); and 90, 120 d (late lactation) postpartum by the weigh-suckle-weigh method. On the following day, milk samples were collected, and foals were weighed and measured for wither height, heart girth, metacarpal length, metatarsal le...
Changes in concentrations of hormones, metabolites, and amino acids in plasma of adult horses relative to overnight feed deprivation followed by a pellet-hay meal fed at noon. Experiment 1 was conducted to characterize the concentrations of prolactin, growth hormone (GH), cortisol, insulin, glucagon, glucose, nonesterified fatty acids (NEFA), urea N, and 10 indispensable amino acids in the plasma of mares (n = 8) and stallions (n = 8) during the last 4 h of a 19-h period of feed deprivation and for 8 h after a noon meal. Experiment 2 was similar to Exp. 1 except that only stallions (n = 8) were used, and they were either fed (n = 4) or not fed (n = 4) at noon in a 2 x 2 Latin square design conducted over two sampling days 7 d apart. In Exp. 1, increases (P < .01)...
The effect of supplemental lysine and threonine on growth and development of yearling horses. Thirty-nine Thoroughbred and Quarter Horse yearlings were used in two 112-d experiments to determine the effect of lysine and threonine supplementation on growth and development. Yearlings were individually fed three dietary treatments that consisted of a pelleted concentrate containing corn, oats, and soybean meal fed to appetite twice daily and Coastal bermuda grass hay group-fed at a rate of 1 kg/100 kg BW. Three concentrates were tested: (A) basal, (B) basal plus .2% lysine, and (C) basal plus .2% lysine, and .1% threonine. Feed intake, weight, withers height, girth, hip height, body lengt...
Effect of various doses of a gonadotropin-releasing hormone analogue on induction of ovulation in anestrous mares. One hundred anestrous mares (early February) were injected s.c. with implants containing 0, .9, 1.8, 3.6, or 5.4 mg of a GnRH analogue (goserelin acetate) in an attempt to induce ovarian cyclicity. Follicular activity and concentrations of progesterone and LH were determined every 3 d, or daily during estrus. In treated mares that ovulated, the interval to the second ovulation of the season was compared to that for an additional group receiving 16 h/d of light beginning December 16 (positive controls). Of the mares that did not ovulate in 30 d, eight from each dose group were challenged on d 3...
Use of gonadotropin-releasing hormone, estrogen, or a combination to increase releasable pituitary luteinizing hormone in early transitional mares. A lack of pituitary LH stores has been implicated as the cause of seasonal anestrus and failure to ovulate during the spring transition period in mares. In this experiment, 40 mares were used to study the effects of GnRH, estrogen, and an estrogen-GnRH combination on increasing releasable pituitary LH. Mares were stratified based on their ability to secrete LH in response to a 950-micrograms challenge of GnRH (n = 10 per group) and then assigned to one of four treatment groups: 1) controls, given no treatment; 2) 1 mg of estradiol-17 beta in oil i.m. daily for 8 d; 3) 200 micrograms of GnRH an...
The effect of added dietary soybean oil on vitamin E status of the horse. Fourteen 2-yr-old Quarter Horses and Quarter Horse x Thoroughbreds were randomly assigned to either a control (CTRL) diet or a diet supplemented with 6.4% soybean oil (SBO). The amounts of both diets that were fed met current NRC nutrient requirements and were isoenergetic with similar nutrient:energy ratios. Venous blood samples (20 mL) were taken at d 0, 30, 60, and 90 of the experiment and analyzed for serum alpha-tocopherol, serum cholesterol, and serum triglyceride. The sum of serum cholesterol and serum triglyceride values was used as an estimate of serum total lipid. The ratio of serum ...
Effects of diet and hindgut defaunation on diet digestibility and microbial concentrations in the cecum and colon of the horse. The effects of diet and hindgut defaunation (removal of protozoa from the hindgut) on diet digestibility (Trial 1) and on total and cellulolytic bacterial and fungal concentrations in the cecum and colon (Trial 2) were investigated. A high-forage (HF) diet, 90% alfalfa hay-10% concentrate, or a higher-concentrate (HC) diet, 60% alfalfa hay-40% concentrate, was limit-fed. In Trial 1, defaunation resulted in a slight decrease in DM digestibility (P < .1) and had no effect on cellulose digestibility. Dry matter digestibility was higher (P < .001) with the HC diet; however, no differences were obs...
Effects of Aspergillus oryzae fermentation extract on in vitro equine cecal fermentation. The objective of this study was to examine the effects of Aspergillus oryzae fermentation extract on the in vitro equine cecal fermentation of soluble starch, amino acids/peptides, coastal bermudagrass hay, and alfalfa hay. Cecal contents were obtained from a cecally fistulated Quarter Horse gelding fed coastal bermudagrass and grain (70:30) either unadapted or adapted to dietary A. oryzae supplementation (2 g/d). Mixed cecal microorganisms were incubated in anaerobic media for either 24 h (soluble starch, amino acids) or 48 h (bermudagrass hay, alfalfa hay). A. oryzae was added to the incubat...
Technical note: equine skeletal preservation techniques to enhance teaching effectiveness. When the decision was made to euthanatize an acutely laminitic Thoroughbred broodmare, graduate students from the Department of Animal Sciences and Industry reconstructed the skeleton for use as a teaching tool. The reproductive and gastrointestinal tracts were removed and preserved in formalin. The hide, muscle, tendons, ligaments, and organs were removed, and the bones were boiled in water for > or = 48 h to remove all remaining tissue. After boiling, the bones were soaked in gasoline to remove fat from the marrow cavities and then soaked in a bleach/detergent mixture as a final cleaning ...
Clinical assessment of selenium status of livestock. Assessment of the selenium status of livestock is an important aspect of production medicine, but variations in reported values between laboratories and between methods may be > 30%. Reliable interpretations require considerable experience with an assay and an extensive database from field and research case samples of a variety of species. The Michigan State University Animal Health Diagnostic Laboratory (MSU-ADHL) has offered Se analyses by acid-digestion and fluorometric detection since 1982. This laboratory expects serum Se values (nanograms per milliliter) of livestock to increase graduall...
Basis for regulation of selenium supplements in animal diets. Selenium was discovered 174 yr ago but, until 1957, was given little notice by biologists or was vilified as an agent that caused toxicity in grazing ruminants and horses in the northern Great Plains. After its status as an essential nutrient was established, Se received intense scrutiny, and hundreds of papers have been published dealing with its metabolic functions and the consequences of a Se deficiency. Because regions of Se deficiency are so extensive in the United States, great efforts have been made to gain Food and Drug Administration (FDA) approval for Se supplementation of animal die...
Dietary selenate versus selenite for cattle, sheep, and horses. Food and Drug Administration regulations currently permit addition of .3 mg of Se per kilogram of diet for chickens, turkeys, ducks, swine, sheep, and cattle. However, field reports indicate that this level may not be adequate for ruminants in all situations. Because sodium selenite is the most common supplemental form and is known to be readily absorbed to particles or reduced to insoluble elemental Se or selenides in acid, anaerobic environments, studies were conducted with dairy cattle, sheep, and horses fed sodium selenate to determine whether Se from this source was more bioavailable than...
Effects of fescue toxicosis on reproduction in livestock. Fescue toxicosis in livestock is due to ingestion of endophyte (Acremonium coenophialum) -infected tall fescue. Understanding mechanisms responsible for decreased calving and growth rates, delayed onset of puberty, and impaired function of corpora lutea in heifers at puberty consuming endophyte-infected fescue is an emerging field in reproductive toxicology. The condition decreases overall productivity through a reduction in reproductive efficiency, reduced weight gains, and lowered milk production. Reproduction in cattle may be further compromised by winter coat retention, increased susceptib...
Growth hormone in mares and stallions: pulsatile secretion, response to growth hormone-releasing hormone, and effects of exercise, sexual stimulation, and pharmacological agents. Short-term patterns of growth hormone (GH) secretion and factors affecting it were studied in mares and stallions. In Exp. 1, hourly blood samples were collected from three mares and three stallions in summer and winter. Although GH concentrations varied in a pulsatile manner in all horses, there was no effect of sex or season (P greater than .1) on plasma GH concentrations and no indication of a diurnal pattern of GH secretion. In Exp. 2, 10-min blood samples were drawn for 8 h from 12 mares; after 6 h, porcine GH-releasing hormone (GHRH) was administered i.v. at 0, 45, 90, or 180 micrograms/...