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K.L. Macmillan M.AGR.SC. PH.D. E.D. Fielden B.V.SC. B.AGR.SC. F.R.C.V.S. 《New Zealand veterinary journal》2013,61(10)
Abstract Extract Sir,—The proportion of return intervals after first insemination of less than 18 days' duration is between 16 and 20% in New Zealand dairy cattle (Macmillan, 1970) whereas the comparable figure in American herds is 3.5% (Moeller and VanDemark, 1951; Flerchinger and Erb, 1954). Since the incidence of these short cycles tends to increase with increasing: herd size, these short return intervals after first insemination may be the result of errors made by the farmer identifying or diagnosing oestrous cows. Such errors will arise because (1) the farmer correctly submits a cow in the first instance but then unnecessarily resubmits the same cow because of incorrect identification or diagnosis; (2) the initial incorrect submission is followed by correct diagnosis and submission; or (3) errors in detection and diagnosis are made on consecutive occasions. 相似文献
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Nine bred gilts were vaccinated with 2 doses of a Clostridium perfringens type C toxoid at a 5-week interval. Time of vaccination during gestation differed among the gilts. Clostridium perfringens beta antitoxin in colostral samples and in serum samples was titrated in mice. Blood was collected from 2 to 5 neonatal pigs from each dam (total = 32 pigs) when the pigs were 36 to 48 hours old. Antitoxin titers in colostrum were 123 to 4.5 IU/ml, indicating considerable variation in individual responses of the gilts to toxoid. Serum titers of neonatal pigs reflected colostrum titers of their dams. This colostrum-to-serum titer correlation was essentially a straight-line fit by least-squares linear regression analysis, establishing a direct proportional relationship between colostrum titers and serum titers of neonatal pigs. In the dams, a correlation was not found between colostral titers and serum titers of blood samples collected 2 weeks after collection of colostrum. 相似文献
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