Effects of Density and Water Availability on the Behavior, Physiology, and Weight Loss of Slaughter Horses during Transport

The aim of this study was to determine the effects of density and provision of water on aggressive behavior, stress, and weight loss in slaughter horses during transport. A 16.2-m, single deck semi-trailer was divided into three compartments to create high, medium, and low density (397 ± 6.5 kg/m², 348 ± 5.2 kg/m², and 221 ± 7.6 kg/m² per compartment) groups of unrestrained horses. Six shipments containing 23 to 30 horses per shipment were transported in June and July of 2004 for 18 to 20 hours. While the truck was stopped for 1 hour after 8 hours of transport and then again just before unloading, horses in each of two compartments received water for 1 hour from six water bowls (three bowls mounted on each side of a compartment). The third, non-watered compartment served as a control. Aggressive behavior of the horses was recorded using 12 video cameras installed in the trailer. All occurrences of aggressive behavior were counted from 15-minute segments of video during 2-hour intervals for each horse that was visible in each density group. Neither density nor water significantly affected (P > 0.21) aggressive behavior, cortisol, plasma chemistry profile, dehydration, or weight loss. Aggression did not differ (P = 0.49) between the first and second halves of the shipments, indicating that fatigue had not advanced to the stage where aggression was suppressed. Individual horses, rather than density were the major cause of aggressive behavior. However, two horses went down in the high density treatment, indicating that factors in high density could lead to increased morbidity or death.     

Stress Response of Three-year-old Horse Mares to Changes in Husbandry System During Initial Equestrian Training

For initial training, horses are often transferred from group housing to individual boxes, which is a potential stressor. In this study, salivary cortisol concentrations, locomotion activity, and heart rate (HR) were analyzed and the HR variability (HRV) variables standard deviation of beat-to-beat interval (SDRR) and root mean square of successive RR differences (RMSSD) were calculated in 3-year-old mares (n = 8). Mares were transferred abruptly from a group stable with access to a paddock to individual boxes without a paddock and were studied from 4 days before to 5 days after changing the stable. Mares underwent routine equestrian training for young horses. On the days before mares were moved to individual boxes, cortisol concentrations showed a diurnal rhythm with values approximately 0.6 ng/ml in the morning and a decrease throughout the day. When horses were moved to individual boxes, cortisol concentrations increased to 1.8 ± 0.2 ng/ml within 30 minutes and did not return to baseline values within 6 hours (0.7 ± 0.1 ng/ml, P < .05 over time). On the following days, a diurnal rhythm was re-established but at a higher level than before the change of stable. Locomotion activity was higher when mares had access to a paddock than when kept in individual boxes. Heart rate increased for approximately 60 minutes when mares were separated from their group. In conclusion, separating young horses from their group and individual stabling are perceived as stressful.     

Uterine Vascular Perfusion and Involution During the Postpartum Period in Mares

In horses, limited data is found regarding the vascular events during uterine involution at the puerperal period. Thus, we aimed to evaluate the morphological aspects (size of uterus and intrauterine fluid content) and the hemodynamics (endometrial and mesometrial vascular perfusion) of the uterus during its postpartum involution process. Ten mares were daily scanned by transrectal color Doppler ultrasonography from the first day postpartum (d1) to the 16th day after first postpartum ovulation (D0 = ovulation). The formerly gravid horn (GH) and formerly nongravid horn (NH) were individually evaluated. A reduction (P < .05) in the uterine diameter was observed during the first 7 days postpartum, and the rate of uterine involution decreased after this period. The involution was completed on d21 and d24 for the NH and GH, respectively. Presence of intrauterine fluid was present in large amounts between d1 and d2 postpartum, followed by a decrease (P < .05) between d4 and d7. No fluid was observed after d16 postpartum or after the third day postovulation (D3). During the early postpartum period, an increase (P < .05) in the endometrial and mesometrial vascularization was detected, respectively, between d1 and d4, and between d1 and d2. The vascular perfusion did not differ after d4 for endometrial tissue, whereas was reduced (P < .05) between d2 and d10 for mesometrium. After the first postpartum ovulation, an increase (P < .05) in vascular perfusion was observed from D0 to D5, followed by a decrease (P < .05) between D5 and D11 and an increase (P < .05) between D11 and D14. The novel vascular perfusion profile here described in the endometrium and mesometrium after ovulation is similar to the uterine vascular profile observed during estrous cycles and early pregnancy, indicating a fast return of the mare's uterus to cycling postpartum conditions.     

Morphological Characteristics of the Placenta and Umbilical Cord of Arabian Mares Foaling in the United Arab Emirates

A total of 127 normal placentas from Arabian mares resident in the United Arab Emirates were examined. The mean linear dimensions of the placenta were, on average, 84% of those previously recorded for the placentas of the Thoroughbred. Significant differences in the size of the allantochorion between primigravid and multiparous mares were seen only in the linear dimensions of the body portion. The pregnant horn was more commonly on the right than left side of the uterus (P = .01; 74/127; 58%). Cord attachment was primarily at the base of the two placental horns (112/127; 88%), with the remainder showing anomalies from this position. The mean (±SEM) total length of the umbilical cords was 62.2 ± 1.2 cm, being composed of the allantoic portion (29.7 ± 0.9 cm) and amniotic portion (32.5 ± 0.6 cm), which averaged 53 ± 0.01% of the total length. The amniotic portion was usually, but not always, longer than the allantoic portion (79/127; 62%). Longer cords were associated with a greater proportion of allantoic length. An enlarged yolk sac remnant (YSR) was present in 16/127 (13%) placentas. Cords with YSRs displayed a significantly longer allantoic portion than those without (P = .02). The total cord length was not correlated with the weight or area of the allantochorion or amnion, any linear measurement of the allantochorion, gestation length, the month of foaling, parity of the dam, or birthweight or sex of the foal. The purpose for which the mare was bred (i.e., racing or showing) influenced the cord length, those of show mares being significantly longer.     

Erythrocyte Osmotic Fragility and Hematological Responses of Horses Administered Ascorbic Acid and Exposed to Road Transportation

The experiment was performed to evaluate the ameliorative effect of ascorbic acid (AA) on some hematological parameters and erythrocyte osmotic fragility (EOF) in horses transported by road. A total of 14 horses, consisting of seven experimental and seven control horses, were used for the experiment. Before the transportation, blood samples were obtained by jugular venipuncture from all the horses. Experimental horses were administered with AA (200 mg/kg dissolved in 20 mL of distilled water per os), whereas the control horses were given 20 mL of distilled water per os. Thereafter, the animals were transported for 6 hours and blood samples collected after transportation. Packed cell volume and hemoglobin concentration were higher (P < .05) in experimental than the control group, whereas total leukocytes reduced significantly (P < .05) in experimental in comparison with the control horses. Lymphocyte, neutrophil counts, neutrophil/lymphocyte ratio, and total protein decreased in experimental horses in comparison with control, but they were not significant (P > .05). Erythrocyte osmotic fragility was lower in experimental than the control at 0.3% NaCl concentration (P < .05). The result of the present study revealed that AA ameliorated changes in hematological parameters and EOF induced by road transport stress, partly because of its antioxidant properties.     

The Effects of Loose Group versus Individual Stall Transport on Glucocorticosteriods and Dehydroepiandrosterone in Yearling Horses

The European Union recently published regulations regarding the welfare of horses during transport, requiring that horses be transported in individual stalls. The objective of this study was to determine whether concentrations of cortisol, corticosterone, or dehydroepiandrosterone (DHEA) differed among horses transported in individual stalls versus in loose groups. A total of 20 yearlings that were regularly handled and accustomed to being tied, but were naïve to transport, were assigned to be transported for 6 hours in either individual stalls or a loose group. The experiment was replicated with a second trial 35 days later following a switchback design. Jugular blood samples were analyzed for plasma cortisol, corticosterone, and DHEA concentrations at pretransport, after 2, 4, and 6 hours of transport, and at 2 and 4 hours after unloading. The data were analyzed using a mixed model repeated measures analysis of variance for treatment effects, whereas differences between sample times within each trial, and pretransport concentrations between trials, were analyzed using paired T-tests. No significant differences were found between treatment groups in concentrations of cortisol (P = .713), corticosterone (P = .370), or DHEA (P = .416). Cortisol and corticosterone concentrations increased significantly during transport, and returned to pretransport concentrations by 2 hours post-transport (P < .01). Changes in concentrations of cortisol and corticosterone indicated that transportation was a significant stressor; however, being transported in a loose group versus individual stalls was not different for these horses.     

Pharmacopuncture Versus Acepromazine in Stress Responses of Horses During Road Transport

Acupuncture has been shown to have the beneficial effect of reducing stress responses in animals and humans. Pharmacopuncture is the injection of subclinical doses of drugs into acupoints to give therapeutic results without side effects. This study compared the effects of injecting the usual dose of acepromazine (ACP; 0.1 mg/kg, intramuscularly [I.M.]) with those of pharmacopuncture (1/10 ACP dose at the governing vessel 1 [GV 1] acupoint) on the stress responses of healthy horses undergoing road transport for 2.5 hours. Four different treatments were applied immediately before loading, with 8 animals/treatment: injection of saline or ACP (0.1 mg/kg, I.M.) at the base of the neck; and injection of saline or 1/10 ACP (0.01 mg/kg) at the GV 1 acupoint. The road transport increased heart rate (HR), respiratory rate, body temperature, and serum cortisol of the untreated horses (injected with saline at the base of the neck). Pharmacopuncture at GV 1 reduced the average HR and transport-induced increase in HR at unloading, without changing the other variables. On the other hand, ACP (0.1 mg/kg) produced significant sedation and reduced the transport-induced increase in respiratory rate but without preventing the stress-induced increase of cortisol. Other acupuncture points and drugs should be tested to verify the beneficial effect of this therapy to reduce stress in horses during road transport.     

Acupuncture Needle Stimulation on Some Physiological Parameters After Road Transport and Physical Exercise in Horse

The aim of this study was to evaluate the effect of acupuncture (AG) treatment on some hematochemical parameters in five Thoroughbred horses after road transport and exercise. Horses competed in two official races. For each race, animals were transported from their stables to the racetrack. Horses transported and competed in the first race represent the control group. Two weeks later, the same horses competed in the second race. Before road transport, they were treated with AG. From animals, blood samples were collected at rest (T_PRE), after unloaded (T_POST), 30 minutes after unloaded (T_POST30), at rest in the transit stall (R_PRE), at the end of the race (R_POST), and 30 minutes after the race (R_POST30). The effect of transport, exercise, and AG was evaluated on blood lactate, glucose, red blood cell, hemoglobin, hematocrit, mean corpuscular volume, and erythrocyte osmotic fragility (EOF) values. A significant effect of transport (P < .05) and exercise (P < .01) was found on all studied parameters in both groups. A significant effect of AG on lactate, glucose, and EOF values was found in transported (P < .001) and exercised horses (P < .05). The results found in this study showed that transport and exercise are potential stressors for the athlete horse that may affect its welfare and physical performance. The data suggest that AG stimulation promoted the increase of blood glucose values and the reduction of lactate and EOF levels suggesting its role in the improvement of the physiological adaptation to stressful stimuli and of physical performance of Thoroughbred horses.     

母马大、小卵泡的卵泡液代谢组学分析及其对卵泡发育的影响

本实验旨在研究母马大、小卵泡液代谢物的差异,从卵泡液代谢组层面初步探讨差异物对卵泡发育的影响及卵泡发育机制。选用8匹山东即墨地区母马的卵泡液进行代谢组学分析,大卵泡直径设为45～60 mm、小卵泡直径设为20～30 mm,采用超高液相色谱-高分辨质谱联用技术,通过主成分分析法(PCA)、偏最小二乘法-判别分析法(PLS-DA)得到大小卵泡液差异性物质质荷比。结果表明:在大卵泡液中含量多的代谢物有睾酮、1-棕榈酰溶血磷脂酸、β-硫酸雌醇、硫酸雌酮,小卵泡液中含量多的代谢物有硫酸吲哚酚、木子塘、水苏糖和3-脲基丙酸酯。综上可知,在大卵泡液中,上调物质主要是类固醇,比较单一集中,但小卵泡中不存在上调的类固醇物质,说明在母马中类固醇激素是促使卵泡发育的主要代谢物;在小卵泡液中,上调物质种类复杂,当优势卵泡出现时,可能有一些代谢物会抑制其余的小卵泡继续发育。     

The Role of Equine Chorionic Gonadotropin in the Stimulation of Luteal Steroidogenesis in Mares Carrying Horse or Mule Pregnancies

The stimulatory role of equine Chorionic Gonadotropin (eCG) in the production of steroid hormones was evaluated during the first 4 months of pregnancy in mares impregnated by either stallions or jack donkeys. Twenty mares were divided in two groups: Mares in the first group were inseminated with stallion semen (horse pregnancies), and those in the second group were inseminated with donkey semen (mule pregnancies). Blood samples were collected twice weekly from day 30 to day 120 of pregnancy to determine the concentrations of eCG, progesterone, androstenedione, and testosterone. Analysis of variance for repeated measures was used to compare the concentrations of each hormone between groups. Linear regression models that considered the linear and quadratic effects of week of gestation as well as the linear and quadratic effects of the concentrations of eCG on the production of each steroid hormone were carried out. Concentrations of eCG, progesterone, and androstenedione were higher in horse than in mule pregnancies (P < .01 for eCG and P < .05 for progesterone and androstenedione). Testosterone concentrations were also higher in horse pregnancies than in mule pregnancies at weeks 7, 9, and 10 (P < .05). Regression analysis indicated that eCG had considerable stimulatory effects on the secretion of progesterone and androstenedione and weaker effects on the secretion of testosterone. The results suggest that eCG stimulates luteal production of progesterone, androstenedione, and testosterone in horse and mule pregnancies, these effects being more evident in horse pregnancies than in mule pregnancies due to the higher concentrations of eCG in horse pregnancies.     

Proliferation and Apoptosis in Fetal Membranes and Endometrium During Placental Retention in Heavy Draft Mares

Placental retention (retained placenta [RP]) is a serious and common peripartum disease in mares, but the etiology and pathogenesis of RP still remain unclear. The alteration of cell proliferation and apoptosis is considered to be an important factor in RP. Fetal membranes and endometrial biopsies were collected from mares with RP (n = 8) and from control mares (n = 10). The proliferation and apoptosis levels in the chorionic and the endometrial epithelia were assessed by proliferating cell nuclear antigen immunostaining and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, respectively. The study revealed that there was an insignificant decrease in proliferation and a significant increase in apoptosis in the chorionic epithelium from mares with RP. This result excludes a proliferation imbalance from the possible causes of RP. In the area of the nonpregnant horn of the placenta, proliferation was negatively correlated and apoptosis was positively correlated with the degree of fetomaternal anchorage. It was observed that, in all mares with placental retention, the endometrial epithelium (both luminal and glandular) showed decreased proliferation and increased apoptosis, which may indicate a delay in postpartum uterine regeneration.     

The Effects of Treatment with N-Acetyl Cysteine on Clinical Signs in Persistent Breeding-Induced Endometritis Susceptible Mares

Persistent breeding-induced endometritis (PBIE) is a major cause of infertility in mares. Endometrial inflammation that persists until embryonic descent ultimately results in early embryonic death. A poor endometrial biopsy grade (IIb or III) has been identified as a risk factor for PBIE. Intrauterine fluid accumulation (>2 cm in depth), pathologic endometrial edema, and elevated intrauterine neutrophil levels are all clinical features of PBIE. Commonly applied treatment options include uterine lavage and oxytocin therapy. N-acetyl cysteine (NAC), a mucolytic used to treat bacterial endometritis in mares, has anti-inflammatory properties and was investigated as a potential treatment for PBIE. A randomized, blinded, cross-over design clinical trial used NAC before breeding in PBIE-susceptible mares (n = 9). Intrauterine infusion of 3.3% NAC was performed 12 hours before insemination, and endometrial cytology and endometrial biopsy samples were obtained at 12 and 60 hours after insemination. Endometrial biopsies were evaluated for the degree of inflammation present. Clinical signs of endometrial edema and intrauterine fluid volumes were assessed by transrectal ultrasound at 12 and then every 24 hours after breeding. Data were analyzed using repeated measures analysis of variance and a Mann Whitney Wilcoxon Test. Treatment with NAC did not improve clinical signs in PBIE-affected mares. However, endometrial biopsies from mares treated with NAC displayed more diffuse and severe neutrophil infiltration than control cycles. Further research using a larger population of mares is required to evaluate the effects of NAC treatment on the endometrium of PBIE-susceptible mares.     

Repeatability and Reliability of Heart Rate Variability in Healthy,Adult Pony Mares

Heart rate variability (HRV) is an important noninvasive method to quantify stress by measuring sympathetic and parasympathetic activity of the autonomic nervous system. Few studies exist on the repeatability and reliability of HRV in equids. The objectives of this study were to (1) compare the effect of different correction factors (CF) available in HRV analysis software on HRV indicator values and (2) to determine the repeatability and reliability of HRV indicators in an unrestricted (pasture) and a restricted movement (equine examination stocks) environment. Data were recorded on five consecutive days from six adult pony mares. Short-term tachograms were compared with regard to software CF by graphical and statistical (Friedman's and Wilcoxon signed rank test) comparison. The results showed that the specific CF influences the HRV indicator values. The strong CF was able to balance the elimination of artefacts without removing the variability of RR intervals and was subsequently used to determine repeatability and reliability. HRV indicators showed good repeatability over the 5 days using Friedman test (pasture, P = .162–.898; examination stocks, P = .29–.865), indicating that there were no significant differences between HRV indicator values. The reliability, represented by intraclass correlation coefficient (ICC) and coefficient of variation (CV), was poor-to-good for pasture data (ICC = 0.44–0.79; CV = 10–68.10) and examination stocks data (ICC = 0.22–0.83; CV = 16.07–62.29). Measurements obtained from the examination stocks were less reliable than those from pasture. Using normalized low-frequency and normalized high-frequency components improved reliability. Free-movement environment-based HRV recordings could ensure better reliability but may require the use of a stronger CF.     

Embryo Transfer in Anovulatory Recipient Mares Treated with Estradiol Benzoate and Long-Acting Progesterone

This study aimed to prepare anovulatory mares in anestrus or in the transitional period as embryo recipients. Ninety embryo-recipient mares were divided into two groups (G). G1 (n = 45) comprised animals in anestrus or in the transitional period; these animals were treated for 3 days (D) with 5, 3, and 2 mg of estradiol benzoate (intramuscular) on D0 (day of the donor's ovulation), D1, and D2 (after ovulation), respectively, followed by weekly application of 400 mg of long-acting progesterone (intramuscular) from D3 after ovulation (donor) until the 120th day of gestation. G2 (n = 45) comprised mares with normal estrous cycles. Plasma levels of progesterone (P₄) were measured on days D1, D2, D8, and D14. Sixty percent of the animals in G1 and 71.1% in G2 (P > .05) completed the pregnancy. On D8, there was no difference in P₄ levels between G1 and G2 animals, but there was a difference in P₄ levels on D14 (P < .05). It was concluded that anovulatory mares in anestrus or in the transitional period could be used as embryo recipients. The protocol was efficient and also considered an appropriate alternative to prepare the uterine environment for embryo transfer; long-acting progesterone administration kept P₄ levels high enough to maintain pregnancy until the 120th day and provided recipients during the time of the year when fewer mares were cycling and ovulating.     

Pilot Study Investigating Fecal Shedding of Salmonella spp. by Horses Used in Competition

This pilot study was performed to determine the need for future investigation of the effect of transportation, environmental changes, and athletic competition on fecal shedding of Salmonella spp. in sport horses. Fecal samples were collected once daily from 20 healthy horses that were competing in National Collegiate Athletic Association equestrian event that occurred over a 3-day period. The horses were divided into four groups with five horses per group. The groups were divided based on travel distance. Fresh fecal samples were collected daily and cultured for Salmonella spp., through bacterial culture, for a minimum of 3 days for three groups that traveled to compete and for 15 days for a group that was housed at the competition location. All fecal samples were negative for Salmonella spp. Although this was a pilot study with a small sample size and limited collection days, the results of this study question the effects of the stress of transportation, new environment, and athletic activity on fecal shedding of Salmonella spp. in horses. A larger study, however, is needed to further investigate these findings.     

Omega-3 Fatty Acid Supplementation Affects Selected Phospholipids in Peripheral White Blood Cells and in Plasma of Full-Sized and Miniature Mares

Dietary omega-3 fatty acids (n-3 PUFA), notably eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), impart health benefits in humans and animals. In horses, dietary n-3 PUFAs elevate EPA and DHA and may promote anti-inflammatory effects. No reports document effects of dietary n-3 PUFA on fatty acyl components of circulating and cellular phospholipids in horses nor whether responses to dietary n-3 PUFA are similar among horse breeds. Ten Quarter Horse and 10 American Miniature Horse mares were assigned to n-3 PUFA (64.4 mg· kg body weight [BW]⁻¹·d⁻¹) or control diet for 56 days. Blood was sampled at 0, 28, and 56 days. Apparent phospholipid molecular species from several classes (phosphatidylcholine [PC]; “ether-linked” phosphatidylcholine [i.e., alk(en)yl, acyl glycerophosphocholine] [ePC]; phosphatidylethanolamine [PE]; phosphatidylinositol [PI]; and phosphatidylserine [PS]) were determined in plasma and peripheral blood mononuclear cells (PBMC) by mass spectrometry. Statistical analysis showed that six phospholipid species had diet × day interactions (P < .05) for both plasma and PBMC. Further evaluation of these species demonstrated that the mole percentage of PC(38:6), PC(40:7), PC(42:10), PE(38:5), PE(40:6), and PE(40:7) (where x:y represents total acyl carbon:total carbon-carbon double bonds) in both plasma and PBMC phospholipids was elevated in horses fed n-3 PUFA (P < .001 for all). Analysis of the acyl product ions revealed that these contained an acyl chain of mass consistent with an n-3 PUFA. Thus, supplementation increased n-3 PUFA in selected plasma and PBMC phospholipids. The absence of breed effects suggests that miniature and full-size horses responded similarly to dietary treatment.     

The Effects of Selenium Source on Measures of Selenium Status of Mares and Selenium Status and Immune Function of Their Foals

The effect of organic and inorganic sources of selenium (Se) on measures of Se status of mares and their foals, Se concentrations of colostrum and milk, and indices of immune function of foals was studied. Twenty late-gestation Standardbred mares were randomly assigned to one of two groups. All mares received an identical balanced ration, except for the source of supplementary Se: one group received organic Se (Se yeast) and the other group received inorganic Se (sodium selenite), fed to deliver 0.3 mg/kg supplementary Se based on total ration dry matter. Mares received the experimental diet from 2 months before estimated due date until 1 month after foaling. Source of Se did not affect Se concentrations in maternal plasma, red blood cells, colostrum, or milk. At 1 month of age, foals from mares fed organic Se had higher red blood cell Se concentration than foals from mares fed inorganic Se (P < .05). Measures of immunity included serum immunoglobulin G concentration, lymphocyte proliferation in response to concanavalin A, and relative cytokine gene expression of stimulated lymphocytes (interferon gamma [IFNγ], interleukin [IL]-2, IL-5, IL-10, tumor necrosis factor alpha [TNFα]) and neutrophils (IL-1, IL-6, IL-8, IL-12, TNFα). Relative gene expression of IL-2, TNFα, and IFNγ by foal lymphocytes was associated with the source of Se supplementation provided to the mares. We conclude that the source of dietary Se provided to mares may influence the immune function of foals at 1 month of age through changes in relative gene expression of certain lymphocyte cytokines.     

Changes in cortisol release and heart rate variability in sport horses during long-distance road transport

It is widely accepted that transport is stressful for horses, but only a few studies are available involving horses that are transported regularly and are accustomed to transport. We determined salivary cortisol immunoreactivity (IR), fecal cortisol metabolites, beat-to-beat (RR) interval, and heart rate variability (HRV) in transport-experienced horses (N = 7) in response to a 2-d outbound road transport over 1370 km and 2-d return transport 8 d later. Salivary cortisol IR was low until 60 min before transport but had increased (P < 0.05) 30 min before loading. Transport caused a further marked increase (P < 0.001), but the response tended to decrease with each day of transport. Concentrations of fecal cortisol metabolites increased on the second day of both outbound and return transports and reached a maximum the following day (P < 0.001). During the first 90 min on Day 1 of outbound transport, mean RR interval decreased (P < 0.001). Standard deviations of RR interval (SDRR) decreased transiently (P < 0.01). The root mean square of successive RR differences (RMSSD) decreased at the beginning of the outbound and return transports (P < 0.01), reflecting reduced parasympathetic tone. On the first day of both outbound and return transports, a transient rise in geometric HRV variable standard deviation 2 (SD2) occurred (P < 0.01), indicating increased sympathetic activity. In conclusion, transport of experienced horses leads to increased cortisol release and changes in heart rate and HRV, which is indicative of stress. The degree of these changes tended to be most pronounced on the first day of both outbound and return transport.     

三种抗牛运输应激技术的效果比较

本研究比较了3种抗应激处理措施防控肉牛运输应激的效果。74头试验牛分4组,分别在运输前用牛支原体弱毒疫苗滴鼻、肌内注射泰乐菌素或饲料中添加泰妙菌素,并设不做任何抗应激处理的对照。分别对试验牛起运前及运达后体温、血细胞数目、血清中酶含量、牛支原体抗体水平、生长速度、发病率、死亡率及治疗成本进行比较。结果显示,起运前及运达后试验牛体温、血细胞数及牛支原体抗体水平未见明显差异;泰乐菌素肌注组试验牛发病率、死亡率显著低于对照组（P〈0．01）;对照组试验牛治疗成本为抗应激处理组治疗成本的15．9倍。结果表明,运输前进行抗应激处理有利于降低肉牛运输应激,起运前肌注泰乐菌素抗运输应激效果最好。