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 |
A review of patterns of change in luteal function. Puberty: For the gilt and filly, the first corpus luteum (CL) appears to have a normal lifespan. For both species, first CL usually is associated with estrus but can form in the absence of estrus. For the ewe and cow, a transient (1 to 4 d, ewe; 3 to 10 d, cow) rise and fall of ovarian derived progesterone (P4) is detected in peripheral blood (80% of ewes; 50% of heifers) prior to first "normal" CL. The first CL of apparent normal lifespan is not accompanied by estrus in the ewe. The first CL in the cow may or may not be accompanied by estrus; first estrus in the cow can be anovulatory. Data a...
Interrelationships between uterus and conceptus to maintain corpus luteum function in early pregnancy: sheep, cattle, pigs and horses. Processes associated with "Maternal Recognition of Pregnancy" are reviewed extensively from the ovine, bovine, porcine and equine species. Comparisons among these species indicate that CL maintenance is achieved primarily by a predominant antiluteolytic-anti PGF effect, and there is strong evidence for antiluteolytic-luteoprotective and luteotropic controls that complement this basic system. The nature of the chemical signals (steroids, prostaglandins and proteins) to regulate these processes among the species are described. Common to all of the species reviewed is a change in vascular dynamic...
Humoral, hormonal and behavioral correlates of feeding in ponies: the effects of meal frequency. The effect of meal frequency on body fluid, glucose, triiodothyronine (T3), heart rate and behavior was measured in 10 ponies. A simple reversal design was used in which each pony received one meal/day (1X) for 2 wk and six meals/day (6X) for 2 wk. The total intake/day was held constant. Feeding was followed by a rise in plasma levels of glucose, T3, protein and osmolality. One large meal was followed by significantly greater changes in all of the variables than was a meal one-sixth the size. Plasma T3 rose from 41 +/- 5 (SE) ng/liter before feeding to 43 +/- 5 ng/liter following a small meal,...
Effects of interrupted photoperiods on the induction of ovulation in anestrous mares. The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian cha...
The influence of dietary selenium levels on blood levels of selenium and glutathione peroxidase activity in the horse. Twenty mature geldings, averaging 535 kg, were used to determine the influence of dietary selenium (Se) on the blood levels of Se and Se-dependent glutathione peroxidase (SeGSH-Px) activity in the horse. Horses were randomly assigned within breed to four treatments consisting of five horses each and fed a basal diet containing .06 ppm of naturally occurring Se. Diets were supplemented with .05, .10 and .20 ppm Se, as sodium selenite. Blood was drawn for 2 wk before, and for 12 wk following, the inclusion of supplement Se in the diets. Whole blood and plasma Se concentrations and plasma SeGSH-P...
Protein requirements of mature working horses. Eighteen mature horses were used to study proteins requirements of working horses. Treatments included intense exercise, medium exercise and maintenance in a 3 X 3 factorial arrangement with three levels of calculated dietary crude protein (CP; 8.5, 7.0 and 5.5%). The horses were on the various exercise-protein treatments for 60 d, then fasted 4 d to evaluate their N status after the treatment period. Exercise had no significant effect on body weight over the feeding and fasting periods. No one exercise or protein treatment expressed the classical low plasma albumin or total protein concentrat...
Effects of dihydrotestosterone benzoate administration on gonadotropin secretion in ovariectomized pony mares. Eight long-term ovariectomized pony mares were treated with either dihydrotestosterone (DHT) benzoate (400 micrograms/kg body weight) in safflower oil or an equivalent amount of oil every other day for 21 d to determine the effects of DHT on follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations in blood samples drawn once daily and after administration of three successive injections of gonadotropin releasing hormone (GnRH). The GnRH injections were given at 4-h intervals on the day following the last DHT or oil injection. Treatment with DHT benzoate did not alter (P gr...
Feeding and drinking behavior of mares and foals with free access to pasture and water. The feeding and drinking behavior of 11 mares and 15 foals living on pasture with free access to water was recorded during 2,340 15-min focal samples taken over 2 yr. Lactating mares on pasture spent about 70% of the day feeding. Foals began feeding on their first day of life. As they grew older, they spent progressively more time feeding, but still spent only 47 +/- 6% of the time feeding by 21 wk of age. Foals fed primarily during the early morning and evening. While grass formed the major proportion of the diet of both foals and mares, they also ate clay, humus, feces, bark, leaves and twig...
Patterns of secretion of luteinizing hormone, follicle stimulating hormone and testosterone in stallions during the summer and winter. Samples of jugular blood were drawn from each of five stallions every 15 min for 12 h during the summer and winter to determine the short-term fluctuations in plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone. Concentrations of LH and FSH were generally not pulsatile, although one stallion exhibited three distinct pulses in these hormones during the winter. In general, patterns of secretion of all three hormones were similar in both seasons and the number of significant rises in hormonal concentrations did not differ between seasons. Concent...
Social facilitation of feeding and time budgets in stabled ponies. Eight pairs of pony mares were observed. Members of a pair were housed in adjacent stalls and fed hay ad libitum. The behavior of both ponies was recorded simultaneously in the morning (1000 to 1200 h) and afternoon (1400 to 1600 h) for a total of 117 h. The time budget was: 70.1 +/- 8.6% eating; 17.8 +/- 7.4% standing (including stand rest, stand alert and stand nonalert); 5.2 +/- 7.0% pushing hay; 2.9 +/- 1.2% walking; 1.9 +/- 2.9% drinking; 1.3 +/- 1.1% self-grooming; .2 +/- .3% defecating; .06 +/- .1% chewing nonfood items; .06 +/- .03% urination; .06 +/- .1% licking salt; .07 +/- .1% pawi...
The effect of artificial rearing on the growth of foals. Fourteen Quarter Horse foals were used to evaluate the effects of artificial rearing on growth. Seven foals were removed from their dams at 3 d of age and fed a reconstituted 26% crude protein (CP) milk replacer free choice for 1 mo, at which time ad libitum solid feeding began. Controls were weaned from their dams at 2 mo of age and fed a 21% CP concentrate ad libitum until the end of the trial. Variables measured during the 26-wk trial were live body weight, height at the withers and length of body from point of shoulder to point of hip. No significant differences were found between the two ...
Effect of age of equine embryos and method of transfer on pregnancy rate. A 2 X 2 cross-classified experiment was conducted to investigate the effect of age of equine embryo (7 vs 8 d postovulation) and method of transfer (surgical vs nonsurgical) on pregnancy rates at 50 d of gestation. Embryos were recovered 7 or 8 d postovulation using a Foley catheter and 3 liters of modified Dulbecco's phosphate-buffered saline (PBS). Upon identification, the embryos were placed in millipore-filtered PBS containing 20% heat-inactivated steer serum and maintained at room temperature until transferred. At the time of recovery, embryos were randomly assigned to be transferred eith...
An investigation of the effect of hesperidin complex and lemon bioflavonoid complex on growth and development of thoroughbred horses. The objective of this study was to determine the effect of Hesperidin Complex and Lemon Bioflavonoid Complex (HC/LBC) on the growth and development of thoroughbred horses. The trial involved twenty-four foals (12 colts, 12 fillies) allotted to treatment shortly after weaning. The study was conducted for a 342-d growing phase and a 153-d training phase, or a total of 495-d. The HC/LBC was included in the test diet at a level calculated to supply the compound at 55 mg X kg body weight-1 X d-1. During the growing phase, average daily gain of colts that received HC/LBC was higher (P less than .05)...
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 ...
Hormonal responses to high and low planes of nutrition in weanling thoroughbreds. Growth-related skeletal diseases in young horses have been associated with high planes of nutrition, although the mechanisms underlying such an association have not been determined. It is likely that nutrition-induced effects on growth rate or growth quality involve the endocrine system. Hormonal and metabolic responses to the ingestion of meals containing either 80% (diet A) or 160% (diet B) of National Research Council energy and protein recommendations were examined in eight Thoroughbred weanling horses after 3 wk of dietary adaptation. After 24 h fasts, prefeeding serum concentrations of t...
Active immunization of prepubertal colts against estrogens: hormonal and testicular responses after puberty. Prepubertal Quarter horse colts were immunized at 6 mo of age with either estrone-17-oxime-bovine serum albumin (n = 4; treated) or with albumin only (n = 5; controls). All colts received booster injections of the appropriate antigen at 8, 10, 12, 16 and 20 mo of age. Blood samples were drawn every 20 d from 6 to 26 mo of age; body weights were determined monthly. Immunization against estrone-albumin resulted in increased binding of [3H]-estradiol in serum within 40 d that was maintained through 24 mo of age. Antisera from treated colts crossreacted equally well with estrone and estradiol and ...
The influence of dietary fiber digestibility on the nitrogen requirements of mature horses. Mature geldings at maintenance were fed different diets in a 4 x 4 Latin square design balanced to account for residual effects in an attempt to determine whether differences in the digestibility of the fibrous portions of feedstuffs would influence dietary nitrogen (N) requirements. Diet 1 contained corn and soybean meal (SBM); diet 2, corn, corn oil and urea; diet 3, corn, SBM, straw and urea; diet 4, corn, alfalfa and urea. Urea supplied 50% of the total N in diets 2 and 3 and 39% of the total N in diet 4. The diets were fed in amounts that met National Research Council (NRC) recommendation...
Testosterone effects on gonadotropin response to GNRH: cows and pony mares. Effects of testosterone propionate (TP) treatment on plasma concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) before and after an injection of gonadotropin releasing hormone (GnRH) were studied using ovariectomized cows and pony mares. An initial injection of GnRH (1 microgram/kg of body weight) was followed by either TP treatment or control injections for 10 (cows) or 11 (ponies) d. A second GnRH injection was administered 1 d after the last TP or oil injection. Concentrations of LH and FSH were determined in samples of plasma taken before and after each GnRH i...
Effects of placement of intravaginal sponges on LH, FSH, estrus and ovarian activity in mares during the nonbreeding season. Eight seasonally anestrous mares were administered intravaginal polyurethane sponges on December 15 and then weekly thereafter until February 1. Control mares received no sponges or genital contact. Sponge insertion caused an immediate surge in follicle-stimulating hormone (FSH) concentrations in jugular plasma in 50% of treated mares whereas no control mares had surges in FSH (P less than .05). The effect of treatment on luteinizing hormone (LH) concentrations was much less dramatic and only three treated mares appeared to have positive responses. Sponge-treated mares exhibited positive respo...
Investigations of the in situ bag technique and a comparison of the fermentation in heifers, sheep, ponies and rabbits. Fiber fermentation using the in situ bag technique was studied in a hay-fed cow. Entry of fine particles into bags of varying pore size, the effect of sample size, rumen contractions, bag porosity and rumen contraction (bags suspended in vitro or in situ) and obstruction of liquid flow through the bag cloth were investigated (Exp. 1). In Exp. 2 fiber degradation in vitro and in situ with 5- and 37-micron pore size bags was measured utilizing six fistulated heifers (four large: 610 kg and two small: 243 kg), two sheep and two goats (30 kg), three ponies (130 kg) and four rabbits (3.2 kg). Degra...
Volatile fatty acids and the role of the large intestine in the control of feed intake in ponies. The roles of volatile fatty acids (VFA) and of the large intestine in the control of feeding in ponies were investigated. Ponies with cecal fistulas were adapted to ad libitum access to pelleted feed. Treatment solutions were given as a bolus 15 min before the animals were allowed free access to feed after a 4-h fast. Each dose of VFA solution was tested in a crossover design with a water control. When the ponies were permitted to eat after the treatments, the latency to eat, first meal size, and duration and first intermeal interval were recorded. Feed intakes were measured at 3 and 18 h afte...
Nitrogen partitioning along the equine digestive tract. Twelve adult horses were fed a corn-oats-timothy hay diet containing 2.87% nitrogen (N) for 4 wk and were then killed. Fresh digesta samples were immediately harvested from the stomach, duodenum, jejunum, ileum, cecum, large colon, small colon, rectum and feces. Total N content of the digesta (on a dry matter basis) increased from the stomach (2.74%) to the duodenum (5.58%; P less than .01), decreased in the cecum (3.10%, P less than .01), remained constant through the large intestine and decreased in the feces (2.10%; P less than .01). High-speed centrifugation of wet digesta and low-speed ce...
Pedigree analysis of four decades of Quarter Horse breeding. Pedigrees of randomly selected Quarter Horses born in each of the years 1946, 1956, 1966 and 1976 and of winning halter, cutting and race horses born in the same years were evaluated and compared. Average inbreeding and inter se relationship levels and relationships of influential ancestors to the sample were calculated for each sample. The amount of Thoroughbred influence and the average generation interval were also determined for each random sample. The levels of inbreeding found in the random samples were low, ranging from 1.3% in 1956 to 2.6% in 1966; however, these levels were higher tha...
Heritability and repeatability of speed for 2- and 3-year-old standardbred racehorses. Repeatabilities (t) and heritabilities (h2) of racing time were estimated from data on 7,206 2- and 3-yr-old Standardbred pacers and trotters competing in 1-mile (1.6 km) charted races at six tracks between 1975 and 1978. A total of 38,487 records representing 2,387 sire progeny groups were divided into subsets by gait, age and track. Initially, the designation "class of race" was recognized as a subjective categorization that reflected nonrandom assignments of horses to races. After extensive investigation, we concluded that racing times should be adjusted by linear regression for the time of...
Testosterone administration to mares during estrus: duration of estrus and diestrus and concentrations of LH and FSH in plasma. To study the possible role of ovarian androgens in regulation of follicle stimulating hormone (FSH) secretion in the cycling mare, five mature, intact mares were treated with testosterone (20 micrograms/kg of body weight) daily during estrus; five control mares received safflower oil on the same schedule. Mares were teased for estrus and samples of jugular blood were drawn daily through one full estrous cycle. Concentrations of FSH in plasma were measured by a newly developed radioimmunoassay based on anti-ovine FSH serum and radioiodinated equine FSH. Testosterone treatment during estrus had ...
Testosterone effects on mares during synchronization with altrenogest: FSH, LH, estrous duration and pregnancy rate. Twelve mares fed altrenogest for 14 d were used to study the effects of a single injection of testosterone propionate on concentrations of follicle-stimulating hormone (FSH) during diestrus, and to relate the normal and perturbed patterns of FSH secretion to subsequent estrous characteristics and fertility. Seven of 12 mares received testosterone propionate at 200 micrograms/kg of body weight on d 5 of progestogen feeding. Mares were teased and blood samples were drawn daily; all mares were artificially inseminated at the first estrus after progestogen treatment. Testosterone propionate treatm...
Effects of melatonin and thyrotropin releasing hormone on mares during the nonbreeding season. Two hormonal treatments, chosen for their effectiveness in other seasonally breeding species, were tested in mares during the nonbreeding season to determine if they could induce ovarian activity and estrus during the winter. Of 15 functionally anestrous (anovulatory) mares, five received intravaginal, polyurethane sponges containing .75 g of melatonin on December 16; fresh sponges containing melatonin were inserted weekly until February 3. These mares also received daily injections of saline. Five other mares received daily im injections of 100 micrograms of thyrotropin-releasing hormone (TRH...
Effects of intragastric loads of xylose, sodium chloride and corn oil on feeding behavior of ponies. This series of experiments was designed to investigate gastrointestinal (GI) stimuli that contribute to the normal control of feed intake in ponies. Osmotic stimuli were tested using intragastric (IG) infusion of .83 osmolar solutions of xylose (250 g) and NaCl (48 g) vs 2-liter water controls. Treatments were given 15 min before ponies were allowed ad libitum access to pelleted feed after a 4-h fast. Both hyperosmotic solutions delayed onset of the first meal (xylose: 72 ± 32 min, P<.05; NaCl: 71 ± 40 min, P<.1), resulting in an immediate reduction (P<.01) in feed intake. No effects were ob...