Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília, Brasília, Distrito Federal, CP 04508, 70910-900 Brazil.
Vet Parasitol. 2009 Dec 23;166(3-4):308-13. doi: 10.1016/j.vetpar.2009.09.037. Epub 2009 Sep 26.
Three sheep farms were used in the Distrito Federal, Central Brazil, to study the occurrence of parasites in the feces. A total of 1798 collections were taken over the period of a year. A total of 1205 were taken in Santa Inês breed (SI) in all three farms, 323 in Bergamasca (Berg), 54 in Ile de France, 49 in IlexSI, 103 in Morada Nova (MN) and 64 in TexelxSI, these last five groups being on a single farm. The animals were drenched soon after weaning and feces collected every 3 weeks to calculate fecal egg count (FEC), at least on two occasions on each animal. In some cases, blood was collected to determine packed cell volume (PCV) at fecal collection. Fixed effects included farm, breed/genetic group within farm, animal age (months), birth type (simple, twin) and sex. (Co)variance components were estimated for Santa Inês sheep using restricted maximum likelihood under an animal model. FECs were affected by month and farm showing that climate and management are important sources of variation for the parasites studied. While age and birth type of the lambs did not affect infection level, their genetic group was important, showing that breeding strategies can help control these parasites. Heritabilities for infection level in the sheep varied between 0.09 for Strongyloides and 0.31 for Moniezia expansa. Genetic selection strategies for sheep aimed at reducing these infections should result in more resistant animals.
本研究在巴西中联邦区的三个绵羊养殖场中，通过粪便样本调查寄生虫的发生情况。在为期一年的时间里，共采集了 1798 份粪便样本。其中，圣伊内斯绵羊（SI）的样本采集量为 1205 份，分别来自三个养殖场；伯格马斯科羊（Berg）的样本采集量为 323 份；法兰西岛羊（Ile de France）为 54 份；伊莱克斯·SI 为 49 份；莫拉达诺瓦羊（MN）为 103 份；特克塞尔·SI 为 64 份，后 5 个品种仅来自一个养殖场。动物在断奶后不久就被驱虫，每 3 周收集一次粪便以计算粪便虫卵计数（FEC），至少对每只动物进行两次。在某些情况下，在收集粪便时还采集血液以确定红细胞压积（PCV）。固定效应包括农场、农场内的品种/遗传群体、动物年龄（月）、出生类型（单胎、双胎）和性别。使用动物模型下的限制最大似然法，对圣伊内斯绵羊的（协）方差分量进行了估计。FEC 受到月份和农场的影响，这表明气候和管理是研究寄生虫的重要变异来源。虽然羔羊的年龄和出生类型不会影响感染水平，但它们的遗传群体很重要，表明繁殖策略有助于控制这些寄生虫。绵羊感染水平的遗传力在 0.09（Strongyloides）至 0.31（Moniezia expansa）之间变化。旨在减少这些感染的绵羊遗传选择策略应能产生更具抗性的动物。
