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151.
Effect of birthweight, total protein, serum IgG and packed cell volume on risk of neonatal diarrhea in calves on two California dairies. 总被引:3,自引:0,他引:3 下载免费PDF全文
J Paré M C Thurmond I A Gardner J P Picanso 《Canadian journal of veterinary research》1993,57(4):241-246
The objective of the study was to determine if there was a relationship between hematological, immunological and physiological variables of newborn calves and risk of diarrhea during the neonatal period. Four hundred and seventeen heifer calves from two dairies (A and B) in the San Joaquin Valley of California were enrolled at birth and scored daily, to 28 days of age, for evidence and severity of diarrhea (0 to 3). Calves were weighted at birth and blood sampled at two to five days of age to determine packed cell volume (PCV), total protein (TP) and IgG serum concentration. The Cox proportional hazards model was used to determine if age at onset of the first diarrhea episode and length of the first episode were associated with the hypothesized variables (PCV, TP, IgG and birthweight). The IgG concentration was not associated with the age at onset of diarrhea (p = 0.6052, Dairy A; p = 0.4393, Dairy B) but a high IgG concentration was associated with a decreased length of episode (p = 0.0325, Dairy A; p = 0.0912, Dairy B), particularly for calves born in the winter on dairy A (p = 0.0211). For calves born in the winter, those with either a high or a low birthweight had diarrhea at a younger age (p = 0.0102, Dairy A; p = 0.0020, Dairy B). Associations were also found for PCV and TP with both the age at onset and length of the first episode of diarrhea. Results suggest that parameters measurable at, or shortly after birth may have important prognostic value in evaluating risk of calf diarrhea. 相似文献
152.
Selectivity of Amblygaster sirm by gill nets of seven mesh sizes ranging from 2.3 to 3.8 cm stretched mesh was studied for a period of 12 months in the coastal waters off Negombo on the west coast of Sri Lanka. The size range of fish caught was 9.0–22.0 cm. Selection by mesh sizes smaller than 3.0 cm was towards the lower end of the selection curve.
Estimated values for selection factors ranged from 5.11 to 6.03 and those for optimum selection lengths varied from 12.9 to 19.7 cm. The highest selection factor was observed for 2.9 cm mesh, probably due to wedging of larger individuals in this mesh. 相似文献
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论嫩江流域水源涵养林工程布局 总被引:1,自引:0,他引:1
从维护东北老工业基地的生态安全出发,立足东四盟实际,着眼于对整个东北地区危害最大,影响范围最大的生态现象列为今后一个时期三北工程建设的战略重点,通过大量调研分析和借鉴专家意见,经筛选整合,初步确定未来东四盟地区三北防护林工程建设的战略重点。 相似文献
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In vitro viability of cryopreserved equine embryos following different freezing protocols. 下载免费PDF全文
P Poitras P Guay D Vaillancourt N Zidane M Bigras-Poulin 《Canadian journal of veterinary research》1994,58(4):235-241
The main objective of this study was to evaluate two freezing protocols and the effect of agar embedding on survival of day 6.5 equine embryos. A total of 133 embryos were used, in one group (n = 51), embryos were first embedded in agar before the freezing protocol was started. A freezing protocol to -30 degrees C or -33 degrees C was used before plunging embryos into liquid nitrogen (LN2). The embryos were thawed in water at 37 degrees C, evaluated and placed in culture. After 24 h culture, the embryos were evaluated for their morphology and development. No differences were observed between embryos plunged at -30 degrees or at -33 degrees C in LN2. The analysis of the morphology and development after thawing showed that the diameter and developmental stage at freezing correlated with embryo survival. Morula and early blastocyst stages of development were associated with better quality after freezing and thawing and had a better potential to survive after in vitro culture (p < 0.05) compared to more advanced stages. The agar failed to protect embryos from zona pellucida damage, but a tendency to prevent rupture was observed in larger embedded embryos. 相似文献
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Physiological and morphological changes in bovine mammary glands following intramammary infusion of recombinant interferon-gamma. 总被引:1,自引:0,他引:1 下载免费PDF全文
Eleven lactating dairy cows were used to evaluate the response of bovine mammary glands to increasing doses of recombinant bovine interferon (rBoIFN)-gamma. Right front and rear quarters were intramammarily infused with eight different doses (10(2) U to 2 x 10(8) U/quarter) of rBoIFN-gamma; each dose was tested in at least two quarters. Left udder halves served as within animal controls in which quarters were injected with a saline placebo or were not infused at all. Milk secretion samples for compositional analysis were collected from each quarter prior to infusion and at 6, 24, 36 and 48 h following infusion. Animals were slaughtered immediately following the 48 h sampling period and mammary tissue was obtained for morphometric analyses. Milk composition was similar between control quarters and those quarters infused with up to 10(5) U of rBo-IFN-gamma during the entire sampling period. Quarters infused with 10(6) U and 10(7) U of rBoIFN-gamma had higher milk somatic cell counts (SCC) following treatment compared with preinfusion values. Changes in the composition of mammary secretion were most dramatic in quarters infused with greater than or equal to 10(8) U of rBoIFN-gamma as indicated by the significant increase in SCC and milk pH with a concomitant decrease in lactose concentration when compared with pre-infusion values or with control quarters. Morphometric analysis of tissue demonstrated an increase in stroma, a decrease in luminal area, and a marked increase in the number of infiltrating leukocytes in those quarters infused with the higher doses of rBoIFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献