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1.
An experiment was conducted to determine the effect of aerobic training after a sedentary period on bone remodeling and Ca and P balance and serum concentrations in varying ages of mature horses. Eighteen stock-type geldings were blocked into three age groups (6 to 10, 11 to 15, and 16 and older years of age), within two groups of nine, with horses randomly assigned to one of two exercise treatments, exercised for 112 days (control) or idle for 56 days followed by 56 days of exercise (treated). Blood samples were taken at the beginning of period I and at 14-day intervals thereafter to determine serum concentrations of osteocalcin (OST), Ca, and P. Dorsal-palmar and lateral-medial radiographs were taken of the left third metacarpal bone on days 0, 56, 84, and 112 to monitor changes in bone density. Total fecal and urine collections were taken for 72 hours on days 0, 56, and 112. Mean serum OST concentrations were affected by treatment (P<.02), time (P<.001); and the interactions of treatment and age (P<.003), time and treatment (P<.001), and time, treatment, and age (P<.001). Overall dorsal (DBRAE), palmar (PRBAE), and medial (MRBAE) RBAE means were affected by time (P<.001), as was overall lateral (LRBAE) RBAE mean (P<.005). Overall DBRAE and PRBAE means were lower (P<.04) at day 56, and higher at day 84 (P<.02) and 112 (P<.001) as compared to day 0. Mean serum Ca concentration was affected by treatment (P<.003) and time (P<.001). Mean serum P concentration was affected by the interaction of time and treatment (P<.001). Mean apparent daily Ca balance was affected bythe interaction of time, treatment, and age (P<.03). Mean apparent daily P balance was affected by treatment (P<.02) and time (P<.001). Biochemical and radiographic data from this experiment suggest that bone remodeling as well as Ca and P balance and serum concentrations are affected by age, inactivity, and exercise in mature horses.  相似文献   

2.
A randomized complete block design experiment was conducted to determine the effect of Ca and P supplementation, inactivity, and subsequent aerobic exercise on Ca and P serum concentrations, and balance and digestibilities in young, mature, and aged horses. Twelve stock-type geldings were blocked into three age groups: 2 and 3, 7 to 11, and 15 to 21 years of age. Two groups of six horses were randomly assigned to either control (C) or mineral supplemented (T) diet. Horses consuming C received about 133% of National Research Council (NRC) requirements for Ca and P, while horses consuming T received about 275% of NRC requirements for Ca and P. The trial consisted of eight 21-d periods. During periods I, II, and III, all horses were inactive, and during periods IV, V, VI, VII, and VIII, all horses performed an ascending aerobic exercise regimen. Serum samples were taken at the beginning of period I and at 21-d intervals thereafter for determination of serum Ca and P. Total fecal and urine collections were taken for 72 h at the beginning of period I and at 21-d intervals thereafter for determination of Ca and P balance. Overall mean apparent Ca balance was affected by treatment (P < .009); time (P < .001); and the interaction of time and treatment (P < .001). Overall mean apparent Ca balance was higher (P < .009) for T as compared to C (23.63 vs. 3.77 mg/kg BW). Mean apparent Ca digestibility was affected by time (P < .001) and the interaction of time and age (P < .001). Mean apparent P balance was affected by time (P < .001) and the interaction of time and treatment (P < .032). Increases in Ca balance may indicate more available mineral for bone metabolism, particularly when remodeling is triggered with the onset of exercise following a sedentary period, suggesting a possible benefit to feeding additional Ca above current NRC recommendations.  相似文献   

3.
This study examined the effects of exogenous equinesomatotropin (eST — Equigen) administration on mineral absorption and retention in two-year-old horses in race training. Sixteen Quarter Horse geldings were paired by age (ave.age=794 d), and one horse from each pair was assigned at random to either the eST treatment group or the control. The experiment was conducted over 112 days during which the horses were gentled to ride and trained on a dirt track in a regimen typical for race horses in training. At 28-day intervals, collections of total fecal and urinary output were made to determine effects on Ca, inorganic P, Mg, Cu and Zn mineral balance.Due to marginal and slightly deficient amounts (P<01)of Ca, P, Mg and Zn intake by days 84 and 112, a result of reduced feed intake to maintain a constant body condition in the presence of a decreased workload, mineral balance for the aforementioned minerals was only examined through day 56. In contrast to the previous minerals, Cu intake appeared adequate. Ca, P, Mg, Cu and Zn intake did not differ (P>.05) by treatment. The eST-treated horses increased (P<.05) Ca retention as a percent of Ca absorbed, had greater (P<.05) overall apparent efficiency of P absorption and greater (P<.05) apparent retention of P on day 56 than the control horses. The eST-treated horses had greater (P<.05) apparent Cu absorption on day 56, greater (P<.05) apparent Cu absorption efficiency on days 56 and 84, and there was a trend (P<.1) for the eST-treated horses to retain more Cu on day 56 than the control horses. Finally, the eST-treated horses retained a greater percent (P<.1) of absorbed Zn on day 56.  相似文献   

4.
In a crossover experiment, eight mature Quarter Horses were exercised by simulated cutting-horse training and fed either a control concentrate (C) or a 10% fat-supplemented concentrate (F) with Bermuda grass hay in a 60:40 ratio. The experiment consisted of two 28-day experimental periods with a 28-day standardization period between treatments. Digestion trials and standardized exercise tests (SET) were conducted every 7 days during experimental periods. Dietary fat had no detrimental effect on digestion of diet constituents, and all digestion coefficients were within expected ranges. Likewise, there was no significant difference in heart rates between treatments or SET days. Plasma lactic acid concentrations did not differ (P > .05) between treatments, however, there was a decline (P < .05) with advancing SET day. When horses were fed fat, there was an increase (P < .05) in muscle glycogen storage from days 0 to 28, but there was no increase (P > .05) in muscle glycogen over time when horses were fed C. On days 7, 14, and 28, muscle glycogen utilization increased (P < .05) from day 0 when horses were fed fat but not C. Pre-exercise data were normalized such that day 0 values equaled zero, due to higher (P < .05) glycogen concentrations for C than F on day 0. Subsequently, muscle glycogen concentrations on day 28 before exercise were higher (P < .05) when horses were fed F than C. The results of this study indicate that Quarter Horses in simulated cutting-horse training can adapt to digestion of a fat-supplemented diet by day 14. However, it may take up to 28 days of adaptation to a fat-supplemented diet to observe increases in glycogen storage and use.  相似文献   

5.
Although previous research suggests that short bouts of high-speed exercise will increase bone mass in horses, little research has been conducted to determine the impact of endurance exercise on bone. Although many in the equine industry believe that months of slow training will increase bone strength, we hypothesized that endurance training would not alter bone mineral content as determined through optical density. Eleven 2-year-old Arabians were split into two groups, Exercised (E, 6 geldings) or Control (C, 5 fillies), with radiographs taken on day 0 for estimation of bone mineral content by radiographic bone aluminum equivalence (RBAE). The E horses were then trained on a high-speed treadmill for 90 days; training consisted of walking (1.6 m/second), trotting (4 m/second) and cantering (8 m/second) at increasing distances until the target of 60 km/day was met. On day 90, E horses were confined to 9 × 14 m dry lots and placed on a regular exercise schedule, including a 60-km endurance test once every 3 weeks. The C horses remained on pasture throughout the study. On day 162, radiographs were made again on all 11 horses. No differences between treatments, days, or interactions were noted in any cortex or the total RBAE, suggesting that endurance exercise does little to alter bone optical density compared with free-choice exercise on pasture.  相似文献   

6.
Sixteen Quarter Horse weanlings were used in a splitplot design experiment to determine the effects of dietary cation-anion difference (DCAD) on mineral metabolism, osteocalcin concentration and variables of growth. Horses were blocked by age and sex and then randomly allotted to two treatment groups (High or Low). Experimental diets with a DCAD of +325 (High, H) and −52 (Low, L) were formed by supplementing diet H with sodium bicarbonate and diet L with calcium chloride. The DCAD was calculated as meq (Na+K)−(Cl+S)/kg of diet DM. The 25-week trial consisted of three 72 h collection periods at 150, 240 and 330 d of age during which a complete urine collection was taken.Multiple fecal grab samples were collected to represent every 2 h post-feeding during each collection period. Venous blood samples were taken for analysis of serum osteocalcin concentration. Weekly measurements were taken to monitor skeletal growth. Representative samples of feed, feces and urine were analyzed for mineral content and apparent mineral balances were calculated by difference. Although osteocalcin concentration did not differ significantly between diets H and L at 150 and 330 d of age, it was higher (P<.05) at d 240 in horses consuming diet H versus diet L. No difference (P>.05) was detected between treatments in any skeletal growth variable measured. Phosphorus balance and digestibility did not differ significantly between treatments across d of age. However, digestibility of P was lower (P<.05) at d 240 and 330 compared to d 150 in both treatments. Horses consuming diet L experienced an increased (P<.05) urinary and a decreased (P<005) fecal excretion of Ca compared to horses consuming diet H. Apparent daily Ca balance was higher (P<.05) in horses consuming diet L than those on diet H at 240 and 330 d of age. Furthermore, Ca digestibility decreased significantly between d 150 and d 240 and 330 in horses consuming diet H. Horses consuming diet L experienced no difference (P>.05) in Ca digestibility across d of age.These findings suggest that horses consuming a low DCAD diet are able to compensate for the increased urinary excretion of Ca by enhancing intestinal Ca absorption and thereby increasing daily CA balance and digestibility.  相似文献   

7.
Thirty juvenile horses were paired by age within sex, and one horse from each pair was randomly assigned to either eST treatment or to a control group. The horses were “broke” to ride and trained in a regimen typical for young racehorses. Radiographs were taken on days 0, 32, 50, 64, 82, 96 and 128 of the study. Increase in total radiographic bone aluminum equivalence (RBAE) was significantly greater in eST treated horses than in the control group (P<.003). Increase in medial RBAE was also significantly greater due to eST treatment (P<.0001). Trends were apparent for increases due to eST treatment in dorsal RBAE (P=.07) and lateral RBAE (P=.07). Bone density was selectively increased in the dorsal, lateral and medial vs. the palmar cortex in the eST treated horses.  相似文献   

8.
Three experiments were conducted to evaluate serum osteocalcin concentrations in normal weanling and yearling Quarter Horses. In Experiment 1, jugular blood samples were taken at 3 hr intervals for 24 hr to evaluate diurnal changes in serum osteocalcin concentration of foals (n=3) and yearlings (n=5). In Experiment 2, twelve Quarter Horse foals were weaned at 4 months of age to determine the influence of sex, weaning and method of weaning of serum osteocalcin concentration. The third experiment utilized fifteen yearling Quarter Horses (7 geldings, 8 fillies) in a two-phase trial to evaluate normal peripheral osteocalcin concentration in sedentary and exercising horses. In Experiment 1, there was no detectable variation (P>.05) in serum osteocalcin concentration during the 24 hr sample period in either age group. In Experiment 2, colts had greater (P<.05) osteocalcin concentrations than fillies at weaning. Method of weaning did not alter mean serum osteocalcin concentration (P>.1). Serum osteocalcin concentrations declined (P<.05) in all horses following weaning but returned to preweaning levels within one week. In Experiment 3, sedentary horses had similar (P>.1) osteocalcin concentrations on d 0, 45 and 90. Serum osteocalcin concentrations of sedentary horses were not affected by sex (P>.1). During exercise, fillies had greater (P<.05) osteocalcin concentrations than geldings. Serum osteocalcin concentrations of all horses declined linearly (P<.0001) during the 90 d exercise period. Osteocalcin may be useful as a tool to assess bone metabolism during growth and physical conditioning in horses. However, variability in serum osteocalcin concentrations due to age, sex and level of activity suggest that these factors must also be considered.  相似文献   

9.
This study examined the effect of supplementation of a bioavailable source of silicon (sodium zeolite A) on altering systemic markers of bone metabolism in horses. Twenty yearlings (ten Quarter Horses and ten Arabians) were randomly grouped as silicon (Si) supplemented (S; n=10), in which yearlings consumed 2% of the total diet as a Si-containing supplement, and a second non-supplemented control group (C; n=10). Blood samples were taken on days 0, 15, 30 and 45. Both plasma and serum were collected; the plasma was analyzed for Si concentrations and serum was analyzed for osteocalcin (OC), carboxy-terminal pyridinoline cross-linked telopeptide region of type I collagen (ICTP), and pyridinoline and deoxypyridinoline crosslinks (PYD). Supplemented yearlings had higher plasma Si concentrations than C yearlings by day 15, and remained higher than C yearlings on days 30 and 45 (P < 0.0001 for all days). There were no differences between treatment groups for OC or PYD concentrations (P > .05); however, ICTP concentrations were lower in S yearlings on day 45 when compared to C yearlings (P = .04). Results indicate that sodium zeolite A supplementation (consumed at 2% of the total diet) increases plasma Si concentrations. Furthermore, results indicate that Si-supplemented yearlings may have decreased bone resorption, which may provide for greater net bone formations, as OC concentrations were not different between groups. Unfortunately, systemic markers give no indication as to the quality of the bone that may be formed, and further research in the area of Si supplementation, bone metabolism and bone strength is required to establish conclusive evidence as to the benefits of supplemental Si to the skeletal system.  相似文献   

10.
Little information has been published concerning the effects of endophyte-infected tall fescue consumption on performance of young growing horses. Therefore, this study evaluated exercise performance and growth by yearlings fed endophyte-infected fescue. Twelve Quarter Horse yearlings (12-16 months of age) were blocked by age and sex and randomly assigned to one of three groups. Group I received native prairie hay (P), Group II received endophyte-free fescue hay (EF) and, Group III received endophyte infected fescue hay (EI). Rectal temperatures were monitored daily and growth parameters (weight, hip and wither heights, and body fat) were measured at the start of the study (d 0) and every 2 weeks throughout the 106 d study. Additionally, blood samples were collected on d 0 and every 28 d for the duration of the study to monitor blood concentrations of calcium, phosphorus, prolactin (PRL), thyroxine (T4), and triiodothyronine (T3). Horses were exercised twice a week for 10-30 min. Respiration, heart rate, and rectal temperature were measured at the start and 5, 30, and 60 min postexercise. Growth parameters and daily rectal temperatures were not different (P >.05) among grdups. No differences (P >.05) occurred among groups in concentrations of serum calcium, phosphorus, PRL, T3, and T4. Respiration rates were lower (P <.05) at 30 and 60 rain postexercise for horses consuming fescue than for horses consuming prairie hay. Postexercise heart rates and rectal temperatures showed no difference (P <.05) among groups. These data suggest that young growing horses being exercised can utilize endophyte-infected fescue efficiently on a short-term basis.  相似文献   

11.
In this study, blood-borne biochemical markers were used to track comparative rates of bone turnover in horses fed differing amounts of Ca, P and Mg. Bone turnover was tracked by serum osteocalcin; bone resorption by the carboxyterminal telopeptide of type I collagen (ICTP); and bone formation by the carboxyterminal propeptide of type I procollagen (PICP). Twenty-one longyearling Quarter Horses were blocked by gender and age, randomly assigned to one of four diets and subjected to 128 d of race training. The study was conducted in 32-d periods, each consisting of 28 d of race training followed by a 4-d fecal and urine collection, or a 4-d rest period. Blood samples were taken weekly during the training period. Serum and plasma samples were analyzed for biochemical markers of bone activity using RIA procedures. Onset of training resulted in elevated blood concentrations of ICTP, PICP and osteocalcin. Concentrations of ICTP and PICP were greater during the first 64 d of training, indicating increased bone activity during the first half of the training period. Horses with the greatest intake of minerals exhibited greater concentrations of PICP (bone formation marker) and lesser concentrations of ICTP (bone breakdown marker). Further, ICTP, PICP and osteocalcin concentrations decreased dramatically following 4-d of confinement and relative inactivity. Therefore it appears that feeding minerals at levels greater than current NRC recommendations provided a protective effect on the developing skeleton of the young racehorse. Additionally, the biochemical markers used in this study were sensitive enough to track daily changes in bone activity resulting from daily changes in stress to the skeleton.  相似文献   

12.
Twelve horses were utilized in a 2 × 2 factorial experiment to investigate the proportionality of the skeleton (small and large framed) and musculature (light and heavy) of mature horses. Large framed horses were longer from the elbow to fetlock, knee to fetlock, hock to fetlock, and from the poll to the end of the nasal bone than small framed horses. Withers height was correlated (P<.001) with the lengths of all long bones (r=.85 to .95) with the exception of the metacarpal bone (r=.69, P<.05). Yet when the lengths of the head, legs, scapula, humerus, femur, tibia, metacarpal, and metatarsals were expressed as a percentage of withers height, no differences between frame sizes were observed.The heavily muscled horses had greater (P<.05) rear quarter width, forearm circumference, gaskin circumference, head width and length than did the lightly muscled horses. The weights of the extensor carpi radialis, biceps femoris, and total round muscle were greater for the heavily muscled horses. Correlations (P<.001) between the weights of the biceps femoris and the total round muscle, total round tissue, and gaskin circumference ranged from .89 to .94 while correlations (P<.001) of the biceps femoris weight with quarter width and extensor carpi radialis were .83 and .82, respectively.Cannon wall area and circumference measurements did not differ for frame size or the degree of muscling but a correlation (r=.75, P<.01) was noted between the cannon circumference taken on the live horses and the actual circumference of the large and small metacarpals.The demonstrated relationship between the lengths of the long bones and height of a horse indicate little value for many of the traditional conformation guidelines governing selection of the ideal conformation horse. Horsemen should realize that many body lengths such as elbow to fetlock actually represented a relatively constant percentage of withers height. Lengths of the scapula, humerus, metacarpal, femur, and tibia also reflected a constant relationship with withers height. The correlations between the extensor carpi radialis and the biceps femoris weights refute the common belief that horses may naturally (no forced exercise) be more heavily muscled in either the fore or rear quarter. Therefore, the data support the theory of proportionality relative to the conformation of the skeletal size and muscling of predominantly Quarter Horse bred horses.  相似文献   

13.
Sixteen Quarter Horse-type geldings were used to examine the response of biochemical markers of bone metabolism to forced exercise prior to and during race training. The study began when the average age of the horses was 15 months. Horses were exercised on a high-speed treadmill for 14 weeks, and were subsequently placed into race training. Serum was collected and assayed for concentrations of osteocalcin (BGP), the carboxyterminal telopeptide of type I collagen (ICTP) and the carboxyterminal propeptide of type I procollagen (PICP). When data were normalized from the onset of race training, ICTP and PICP concentrations were higher in the pre-exercised horses (P<.05 and P<.1, respectively) indicating higher rates of bone turnover. Overall, bone turnover appeared to be decreased during race training, as concentrations of PICP and ICTP were lower when compared to values seen during the pre-training Phase.  相似文献   

14.
This study demonstrated that the feeding of treatment diets with calculated dietary cation-anion balances (DCAB) of +370.43 (H) and -25.69 (L) did not have significant effects on blood pH, pCO2, and HCO3-. Serum Ca2+, P, Na+, and Cl- as well as plasma PTH did not differ (P > .05) between the two treatment groups. Serum K+ was higher (P< .05) in horses fed diet H rather than diet L. The DCAB of the diet significantly affected urinary Ca2+, P, Na+, K+, and Cl- excretion in the young growing horse. Urine Ca2+ and Cl- levels were higher (P < .01) in horses fed diet H versus diet L. Furthermore, levels of P, Na+, and K+ in the urine were higher (P < .01) in horses on diet H as opposed to diet L. Results of this study indicate that horses were able to maintain acid-base status regardless of diet. However, these data imply that growing horses consuming diets low in DCAB may be predisposed to abnormal bone mineralization due to the increase in calcium excretion which could lead to a weakening of the skeletal system.  相似文献   

15.
Seventeen Arabian weanlings were used to determine the influence of housing on third metacarpal bone mass. Animals were separated into three treatment groups: Pasture (n = 6), Stall (n = 5), and Partial-Pasture (n = 6). Radiographs of the left third metacarpus were taken every 28 d to determine radiographic bone aluminum equivalence (RBAE). Serum was collected every 14 d and analyzed for osteocalcin, carboxyterminal telopeptide of type I collagen (ICTP), and keratan sulfate. Hip and wither height, BW, and cannon circumference were measured every 28 d. Lateral RBAE in the pastured group increased linearly from d 0 to d 56 (P = 0.001). In the Pasture group, total RBAE increased from d 0 to 56 (P = 0.05) and medial RBAE tended to increase from d 0 to d 28 (P = 0.06). The Partial Pasture group increased from d 0 to 56 in medial (P = 0.02) and tended to increase in total RBAE (P = 0.08). Although the Stall group demonstrated an increase in total RBAE from d 0 to 56 (P = 0.04), the Partial Pasture group tended to have greater total RBAE than the Stall group at d 28 (P = 0.08), and the Pasture group had greater lateral RBAE at d 28 (P = 0.005) and 56 (P = 0.007) than did the Stall group. At d 28, medial RBAE was greater in the Pasture (P = 0.003) and Partial Pasture (P = 0.05) groups than in the Stall group. Pasture and Stall groups tended to decrease in osteocalcin (P = 0.06), whereas Partial Pasture weanlings decreased (P = 0.01) from d 0 to 56. All treatment groups decreased from d 0 to 56 in ICTP (P < 0.01). Pastured weanlings decreased from d 0 to 42 in serum keratin sulfate (P < 0.05), whereas the Stall group decreased from d 0 to 56 (P = 0.05). All treatment groups increased in wither height (P < or = 0.01), hip height (P < or = 0.001), and BW (P < or = 0.01). Both the Pasture and Partial Pasture weanlings demonstrated greater cannon circumference than Stall weanlings on d 28 (P < or = 0.05) and 56 (P < or = 0.005). These data demonstrate that pasture rearing or 12-h daily turnout is beneficial to maintaining and increasing bone mineral content in weanling Arabian horses.  相似文献   

16.
Total blood volume (TBV) was measured on 47 mature race-retired Thoroughbreds and compared with individual performance records. TBV had a near normal distribution with a mean of 49.2 ± 5.0 L. Thirty-three of the 47 horses (70.2%) were stakes horses (SH). There was a difference (P < .01) in the percentage of SH with below average (BA) TBV (36.4%) compared with the percentage of SH with average (A) TBV (73.1%) and an even greater difference (P < .001) when compared with horses with above average (AA) TBV (100%). Further, there was a difference (P < .001) in the percentage of graded stakes horses (GSH) with BA-TBV (0%) compared with those with A-TBV (23.1%) and AA-TBV (30%). TBV was related (P < .05) to overall performance level (r = 0.45). There was no difference in the average earnings per start (AEI) of horses with BA- and A-TBV; however, horses with AA-TBV had a higher (P < .05) AEI, and overall TBV was related to AEI (r = 0.34). TBV is a measure of oxygen delivery capacity, and since it is inherent to the individual, values from yearlings and unraced 2-year-olds should provide buyers with an objective, performance-related physiologic parameter to use in selection.  相似文献   

17.
Fifty-three Quarter Horses were put into race-training at 18 mo of age. Changes in the third metacarpal were monitored by radiographic densitometry initially at 83 days prior to the commencement of training and at days 0, 62, 104 and 244 of training. A normal increase in density of the third metacarpal due to growth and mineralization was seen from the first set of radiographs until the horses began training at day 0 (P<.001). Bone density then decreased to day 62 (P<.001), remained low through day 104 before it began to increase to day 244 (P<.005). Differences in the most optically dense portion of each cortex of the third metacarpal were compared in horses completing the study without injury and those sustaining a bone-related injury. Horses experienced fewer injuries when they had greater cortical mass in the lateral (P<.05) and medial (P<.1) aspects of the third metacarpal, relative to the palmar aspect, at the commencement of training.  相似文献   

18.
This experiment was conducted to determine if additional mineral supplementation during early training would increase mineral retention and improve the strength of bone as indicated by the mineral content of the third metacarpal. Twelve previously untrained Quarter Horse geldings were randomly divided into two groups, broke to ride, trained to gallop on the track and maintained in training for four 28-day periods. One group of four horses served as controls and was fed a ration averaging 28.3 g of Ca/day and 21.9 g P/day while in training. Eight other horses were fed a ration averaging 34.9 g Ca/day and 26.4 g P/day while in training. Feed, feces and urine were analyzed to determine mineral balance. Radiographs were taken of the left front leg to examine bone density as indicated by radiographic bone aluminum equivalence (RBAE). The high mineral treatment group retained more Ca than controls (P<.05) at days 56 and 84. An increase in Ca retention would prove beneficial in facilitating the bone remodeling process and overall skeletal growth. Additionally, the high mineral group had a greater increase in total RBAE (P<.05) when compared to the control group. Hence, it appears that benefit was derived from feeding the greater amount of Ca to the young racehorse at the onset of training.  相似文献   

19.
Six mature Quarter Horse mares were used in a crossover design to assess the effect of dietary protein level on metabolic response to exercise. After a 2-wk adaptation period to either a 12.9% (control) or an 18.5% CP (high-protein) diet, each mare performed a standard exercise test. The test consisted of a 15-min exercise period at 4.5 m/sec on a 9% grade motorized treadmill. Exercise resulted in an increase in heart rate (P less than .001), but there was no difference (P less than .05) between dietary treatments. In the jugular vein, lactate increased (P less than .01) from 6.3 to 52.0 mg/100 ml in the control group and increased from 6.3 to 45.6 mg/100 ml in the high-protein group. There was an interaction (P less than .05) between diet and exercise for lactate. Plasma NH3 increased (P less than .001) during exercise, but not until the 15th min, at which time NH3 increased over fourfold in both groups. Dietary protein did not affect NH3; however, urea-N was higher (P less than .001) in horses receiving the high-protein diet. Plasma alanine increased from 13.6 to 30.3 mumol/100 ml and glutamine increased from 49.3 to 62.5 mumol/100 ml in the control group. In the high-protein group, alanine increased from 10.2 to 25.8 mumol/100 ml, whereas glutamine increased from 39.3 to 49.2 mumol/100 ml. Our study detected no metabolic evidence for a detrimental effect of excess dietary protein in horses exercising on a graded treadmill at 4.5 m/sec for 15 min.  相似文献   

20.
Concentrations of the cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and osteocalcin (OC) have been determined in the serum of one hundred clinically healthy adult Draught or Warmblood horses. The correlation between these two markers has been evaluated and the influence of gender, age and type of horse described. No significant variations were observed between animals of different sex, but a significant inverse correlation (P<0.0001) with age was observed for both measured parameters. After correction for age, serum levels of OC were found to be lower in Draught [adjusted least square mean (LSM)=6.612μg. L−1] than in Warmblood horses (adjusted LSM=8.596μg.L−1), whereas levels of ICTP were higher in Draughts (adjusted LSM=8.035pg.L−1) than in Warmbloods (adjusted LSM=6.643μg.L−1). A significant correlation (P<0.0001) was observed between OC and ICTP. This correlation was stronger if the type of horse was taken into account in the statistical model. The ratio OC:ICTP was independent of gender and age. A higher OC:ICTP ratio in Warmbloods compared to the Draught horses might reflect a higher bone remodelling level of horses submitted to regular daily work. It was concluded that ICTP and OC are influenced by the type of horse, and probably reflect a physiological difference in bone remodelling between these animals.  相似文献   

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