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Query: UMLS:C0851341 (infestation)
 10,121 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nine yearling crossbred beef steers, Bos taurus L., were used to examine physiological responses to Gulf Coast tick, Amblyomma maculatum Koch, infestation. Steers were stanchioned indoors in individual environmentally controlled rooms. On day 0, each animal received 0, 25, or 75 pairs of ticks. Physiological variables measured daily were feed intake, heart rates, rectal temperatures, and respiration rates. Blood samples were collected from each animal on days 7, 21, and 42 for serum constituent analysis. To monitor metabolic hormone status, intensive blood samples were collected hourly for 6 h on days 21 and 42. Throughout the treatment period, feed intake values were similar among treatments resulting in comparable body weight at the end of the trial. Heart rates and rectal temperatures were unaffected, however, respiration rates of steers infested with 25 pairs of ticks were higher than the other treatment groups. Treatment effects were detected in uric acid concentrations on day 7 in steers infested with 75 pairs of ticks. Treatment effects were detected in total, direct and indirect bilirubin, gamma-glutamyl transpeptidase, and aspartate amino transferase concentrations. Likewise, creatine kinase concentrations were higher in the tick-infested steers on day 7. Elevated white blood cell counts were observed in tick-infested steers. All other serum components were similar and were within their normal ranges. Serum insulin, prolactin, growth hormone, and cortisol concentrations were unaffected by tick infestations. Gulf coast tick infestation resulted in altered blood composition indicative of infection caused by tick feeding habits.
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PMID:Physiological responses of beef cattle to Gulf Coast tick (Acari: Ixodidae) infestations. 772 83

Nine yearling crossbred beef heifers, Bos taurus L., were used to examine physiological responses to horn fly, Haematobia irritans (L.), infestation. Heifers were stanchioned indoors in individual environmentally controlled rooms. On day 0, each animal received 0, 500, or 1,000 horn flies. Fly numbers were adjusted daily to maintain an appropriate infestation for each heifer. Feed intake, respiration rate, and rectal temperature was recorded daily. In addition, blood samples were collected from each animal on days 0, 12, and 33 for serum constituent analysis. To monitor metabolic hormone status, intensive blood samples were also collected hourly for 6 h on days 0, 12, and 33. Throughout the period of treatment, feed intake values were similar among treatments resulting in comparable body weight at the end of the trial. Respiration rates on each day were similar among groups. Rectal temperature was also unaffected by horn fly infestations. Serum electrolyte analysis revealed that neither Na, K, Cl, Ca, P, nor Fe differed among treatments. Likewise, HCO3/CO2 ratio, anion gap, and serum osmolality did not differ among treatment groups. Major indicators of nutrient status (glucose, cholesterol, triglycerides, urea N, creatinine, uric acid, albumin, globulin) and insulin, growth hormone, and prolactin were also unaffected. Serum bilirubin and enzyme (alkaline phosphatase, creatine phosphokinase, gamma-glutamyl transpeptidase, lactic dehydrogenase, aspartate amino transferase, alanine amino transferase) concentrations were similar in control heifers and those infested with horn flies.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Serum constituent profiles of beef heifers infested with horn flies (Diptera: Muscidae). 783 15

Forty-eight Angus x Hereford steers (initial BW = 336 +/- 8.3 kg) were used in a 56-d study to evaluate growth and endocrine responses to continuous or discontinuous grazing of high-endophyte-infected Kentucky-31 (K; > 57% infestation rate) or low-endophyte-infected Johnstone tall fescue (J; < 1% infestation rate) and implantation with 0 or 24 mg/steer of estradiol-17 beta (E2; Compudose). Steers were allotted by weight to eight 3-ha paddocks (four paddocks of each fescue variety) with six steers per paddock. Two paddocks of each variety were grazed continuously (KK and JJ), whereas steers on the remaining four paddocks were rotated every 14 d from K to J (KJ) or from J to K (JK). Three steers in each paddock were implanted with E2 on d 0. The study extended from May 25, 1988 to July 20, 1988 with steers exposed to potential heat-stress conditions for 52 d of the 56-d study. Body weights were obtained on d 0, 28, and 56, and blood samples were taken on d 28 and 56. Overall ADG, serum prolactin, and serum alkaline phosphatase activity were greater (P < .05) in JJ than in KK steers. Rotation from K to J did not increase overall ADG, prolactin, insulin-like growth factor I (IGF-I), or alkaline phosphatase activity compared with the continuously grazed KK, whereas JK steers had lower (P < .10) ADG, prolactin, and alkaline phosphatase activity than JJ steers. Estradiol-17 beta increased (P < .10) IGF-I in JJ, KJ, and JK steers but not in KK steers.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Growth and endocrine responses of cattle to implantation of estradiol-17 beta during continuous or discontinuous grazing of high- and low-endophyte-infected tall fescue. 846 63

During December/January 1996/97 typical summer syndrome (hyperthermia and a 30% drop in milk yield) occurred in succession in two Holstein dairy herds (n=240 and n=150 milking cows, respectively) on the South African Highveld. These farms are situated in the midst of the prime maize and dairy farming areas of South Africa where this condition had never been diagnosed before. The individual components of the concentrate on both farms were negative for ergot alkaloids. Endophytic fungi and/or ergot infestation of teff and other grasses fed to the cows were then suspected of being involved, but neither endophytes nor ergot alkaloids could be implicated from these sources. By measuring the serum prolactin levels of groups of sheep (n=5) fed the first farm's total mixed ration (TMR) or its three individual fibre components for a period of 11 days, the source of the ergot alkaloids was identified. A statistically significant decrease in the level of this hormone occurred only in the group on maize silage (which constituted 28% on dry matter base of the TMR). The involvement of the maize silage was further chemically confirmed by the high levels of total ergot alkaloids, predominantly ergocryptine, found by LC-MS in the silage as well as in the TMR (115-975 ppb and 65-300 ppb, respectively). The ergot alkaloid content (mainly ergocryptine) of the maize silage on the second affected farm was 875 ppb. Withdrawal of contaminated silage resulted in gradual recovery of stock on both farms. Nut sedge (Cyperus esculentus and Cyperus rotundus of the family Cyperaceae) has a world-wide distribution and is a common weed in annual crops, and can be parasitized by Claviceps cyperi. Careful examination of the maize silage from both farms revealed that it was heavily contaminated with nut sedge and that it contained minute sclerotia, identified as those of Claviceps cyperi, originating from the latter. Nut sedge was abundant on both farms and it is believed that late seasonal rain had resulted in mature, heavily ergotised nut sedge being cut with the silage. Claviceps cyperi sclerotia, collected on the affected fields in the following autumn contained 3600-4000 ppm ergocryptine. That the dominant alkaloid produced by this particular fungus was indeed ergocryptine, was confirmed by negative ion chemical ionization MS/MS. In one further outbreak in another Holstein herd, teff hay contaminated with ergotised nut sedge and containing 1200 ppb alkaloids, was incriminated as the cause of the condition. This is the first report of bovine ergotism not associated with the Poaceae infected with Claviceps purpureum or endophytes but with the family Cyperaceae and this particular fungal phytopathogen.
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PMID:Claviceps cyperi, a new cause of severe ergotism in dairy cattle consuming maize silage and teff hay contaminated with ergotised Cyperus esculentus (nut sedge) on the Highveld of South Africa. 1599 3