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Twenty-seven crossbred calves (1/2 Simmental, 1/4 Hereford, 1/4 Brahman) averaging 257 +/- 11 d of age were either hot-iron-branded (H), freeze-branded (F), or sham-branded (S). Calves were blocked for temperament, weight, and sex and were randomly assigned to day and order in which treatments were applied. To reduce stress from handling at treatment time, each calf was herded through the squeeze chute daily for 5 d before the experiment. Jugular cannulas were inserted in each calf 1 d before application of treatment. Blood samples and heart rate measures were obtained at -5, -3, 0, .5, 1, 3, 5, 10, 15, and 20 min after application of the treatments. Mean concentrations of plasma epinephrine (EPI) were higher for H calves at time .5 min than for either S or F calves (P = .10). To account for individual differences, prebranding heart rates and hormone concentrations were subtracted from subsequent samples and were also used to calculate a proportion for each subsequent sample. Analyses of subtracted values found that EPI concentrations were greater for H calves than for either S or F calves (P = .007) at .5 min postbranding. No other differences were found for the subtracted analyses. Analyses of proportion data also revealed that H calves had greater EPI than did either S or F calves (P = .027) at .5 min postbranding. Only three animals vocalized during branding, one H calf and two F calves. Despite the 5-d acclimation period, handling and restraint elevated plasma cortisol concentrations and heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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AIM: To investigate a possible interaction between lolitrem B and ergovaline by comparing the incidence and severity of ryegrass staggers in sheep grazing ryegrass (Lolium perenne) containing lolitrem B or ryegrass containing both lolitrem B and ergovaline.

METHODS: Ninety lambs, aged approximately 6 months, were grazed on plots of perennial ryegrass infected with either AR98 endophyte (containing lolitrem B), standard endophyte (containing lolitrem B and ergovaline) or no endophyte, for up to 42 days from 2 February 2010. Ten lambs were grazed on three replicate plots per cultivar. Herbage samples were collected for alkaloid analysis and lambs were scored for ryegrass staggers (scores from 0–5) weekly during the study. Any animal which was scored ≥4 was removed from the study.

RESULTS: Concentrations of lolitrem B did not differ between AR98 and standard endophyte-infected pastures during the study period (p=0.26), and ergovaline was present only in standard endophyte pastures. Ryegrass staggers was observed in sheep grazing both the AR98 and standard endophyte plots, with median scores increasing in the third week of the study. Prior to the end of the 42-day grazing period, 22 and 17 animals were removed from the standard endophyte and AR98 plots, respectively, because their staggers scores were ≥4. The cumulative probability of lambs having scores ≥4 did not differ between animals grazing the two pasture types (p=0.41).

CONCLUSIONS AND CLINICAL RELEVANCE: There was no evidence for ergovaline increasing the severity of ryegrass staggers induced by lolitrem B. In situations where the severity of ryegrass staggers appears to be greater than that predicted on the basis of concentrations of lolitrem B, the presence of other tremorgenic alkaloids should be investigated.  相似文献   

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Brahman (n = 9) and 1/2 Simmental x 1/4 Brahman x 1/4 Hereford (n = 11) calves were utilized to determine the influence of exposure to cold on the physiology of the neonate. All calves were removed from their dams within 20 min of birth and prior to suckling. Calves were assigned randomly within breed to either a warm (W; 31 degrees C) or cold (C; 4 degrees C) environmental treatment group. Jugular blood samples were collected via indwelling catheters at 20-min intervals for 180 min. At 100 to 120 min of sampling, all calves were given 1.2 liters of colostrum from their dams via stomach tube. At 120 min, C calves were placed in the W environment. Calf vigor score (CVS) and rectal temperature were determined at each time blood was collected. Serum or plasma was analyzed for glucose (GLU), lactate (LAC), blood urea nitrogen (BUN), hemoglobin (HEM), triglyceride (TRG), triiodothyronine (T3), thyroxine (T4), insulin (INS), cortisol (CORT) and nonesterified fatty acid (NEFA) concentration. Rectal temperature was lower (P less than .01) in C Brahman than in W Brahman and C or W crossbred calves. Crossbred calves had higher (P less than .01) CVS than Brahman calves. Calves in W had lower (P less than .01) GLU than C calves. Brahman calves had higher GLU, LAC, BUN, TRG, T3, T4 and CORT (P less than .05) than crossbred calves. The C Brahman calves had the highest (P less than .05) TRG, CORT, T3 and T4 of all groups. Concentration of NEFA were higher (P less than .01) in C than in W calves.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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Akabane disease in sheep   总被引:1,自引:0,他引:1  
Perinatal lamb mortality, associated with malformations of the CNS due to Akabane viral infection, occurred in 4 of 9 flocks of ewes lambing on 3 farms between 26 May and 14 November, 1976. Cases were restricted to ewes conceiving prior to the second week of March and lambing between 26 May and 19 July. As judged by seroconversion in sentinel flocks on 2 of the farms, field infection with Akabane virus occurred mainly between mid-February and mid-April. Malformations of the CNS occurred in 42.5%, 51.2%, 100% and 31.0% of the dead lambs examined in the affected flocks respectively. Prevalence in the 4 affected flocks, expressed as the proportion of ewes lambing which delivered at least one malformed foetus, was 6.1%, 8.4%, 88.9% and 5.7% respectively. Lamb mortality due to malformations of the CNS was 7.1%, 5.5%, 92.3% and 5.7% of lambs born. Age-specific prevalence was calculated for 3 of the 4 flocks and 2-year-old ewes accounted for 71.4% and 76.9% of total cases respectively in 2 flocks, whereas in one flock malformations occurred at equivalent frequencies throughout several older age groups. Birthweights of affected lambs were usually significantly lighter than those of unaffected lambs of similar sex and birth-type, and their mean duration of gestation was slightly, and significantly, prolonged. Micrencephaly (88.1% of cases) and hydrocephalus (68.7% of cases) were the outstanding pathological features of the malformations with hydranencephaly, microgyria, porencephaly and attenuation of the spinal cord occurring at much lower frequencies.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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Ovarian and gonadotropin responses to insulin and energy restriction were investigated in a 2 X 2 factorial experiment using 2-yr-old Brangus heifers. Thirty heifers were paired by weight and body condition, then assigned to treatment groups receiving 75 (LE) or 180% (HE) of NRC recommendations for dietary energy for maintenance. Diets were adjusted weekly to maintain daily .25 to .5 kg weight loss or 0 to .25 kg weight gain, respectively. On d 10 of the first estrous cycle subsequent to the initial 45 d of feeding, heifers within each dietary group were allocated to receive twice daily infusions of either 40 U insulin (I) or saline (C). Infusions began at 5 and 10 h postprandial and were given in six boluses, 20 min apart. Infusions continued daily until d 20 or estrus, whichever occurred first. On d 11, blood samples were collected at 15-min intervals for 12 h to determine luteinizing hormone (LH) and insulin concentrations. On d 16 to 20, twice daily im injections of 1 mg follicle stimulating hormone (FSH) were administered. Heifers were ovariectomized on d 11 after estrus. Number of corpora lutea (CL) in LE-I heifers was greater (P less than .05) in LE-C, HE-C or HE-I. Total CL weight (g) per heifer was greater (P less than .05) in HE-C and LE-I heifers than in LE-C. Individual CL wt was heavier in HE than in LE heifers (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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Twenty-nine prepubertal Holstein heifers were assigned by age to one of three age groups to determine if the prepubertal bovine uterus could respond to an oxytocin stimulus. Group 1 heifers were 6 to 7 months of age (AGE1; n = 11), group 2 heifers were 8 to 9 months of age (AGE2; n = 11) and group 3 heifers were 10 to 11 months of age (AGE3; n = 7). Blood samples were collected via an indwelling jugular catheter. Four samples were collected at 15-min intervals prior to oxytocin administration to determine basal 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) concentrations. Each heifer received 100 IU of oxytocin i.v., blood sampling continued at 5 min intervals for the next 30 min and for an additional 90 min at 15-min intervals. Heifers were considered responders to oxytocin if mean PGFM concentrations increased at least 1.5 times the SD of their basal PGFM concentration. Age of the heifer (P less than .0001) and responder status (P less than .05) affected plasma PGFM. Plasma PGFM was higher in AGE1 and AGE3 heifers than AGE2 (P less than .0001). The number of responders was greatest at AGE3 (P less than .03) with AGE1 and AGE2 being similar. Mean basal PGFM was lower (P less than .04) at AGE2 than AGE1 with AGE3 being intermediate. In addition, basal PGFM at AGE1 tended to be lower (P less than .08) in the responders than in the non-responders, while AGE2 basal PGFM did not differ between responders and non-responders (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
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