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根据特种设计的基本原理 ,介绍了用混杂设计、平衡不完全区组设计以实施基因型同质试验单元较少而处理数较多的试验。这两种设计的基本特点是采用混杂的原理缩小不完全区组的大小 ,使较少的基因型同质试验单元可安排一个不完全区组所需的处理。并各列举了 1个畜牧方面的试验演示其分析过程。 相似文献
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Critical appraisal skills enabling assessment of the validity and importance of evidence are essential for clinicians to make informed decisions regarding what new information should be incorporated into their clinical practice. This review highlights key points to consider in a critical review concentrating on common study designs used in the equine literature. 相似文献
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Jason J Hayer Dorit Nysar Cline Heinemann Caroline D Leubner Julia Steinhoff-Wagner 《Journal of animal science》2021,99(10)
Consumers, industrial stakeholders, and the legislature demand a stronger focus on animal welfare of all livestock at the farm level by using suitable indicators in self-assessments. In order to deduce farms’ animal welfare status reliably, factors that influence indicators’ results need to be identified. Hence, this study aimed to apply possible animal welfare indicators for unweaned dairy calves on conventional dairy farms with early cow–calf separation and evaluate influencing factors such as age and sex of calves or climatic conditions on the applied indicators’ results. An animal welfare assessment using 7 resource-based and 14 animal-based indicators was conducted at 42 typical Western German dairy farms (844 calves) in 2018 and 2019 by two observers. The effect of influencing factors was calculated by binary and ordinal logistic regressions and expressed as odds ratios. Although every unweaned calf was assessed during the farm visits, most farms had relatively few unweaned calves (average number of calves ± standard deviation = 20.1 ± 6.7 calves), with six farms having not more than 10 calves. The small sample sizes question the usage of those indicators to compare between farms and to set thresholds at the farm level. Only one assessed indicator (cleanliness core body) was not statistically affected by the evaluated influencing factors. Calf age was identified as the most decisive factor, as it affected 16 of 21 evaluated indicators, and calf age distribution on-farm varied greatly. Climatic conditions (ambient temperature and rainfall) influenced resource-based indicators such as access to concentrate and water or the cleanliness of feeding implements and bedding as well as animal-based cleanliness indicators and the occurrence of health-related impairments such as coughing and diarrhea. The authors found differences between calves on farms assessed by the different observers not only in resource-based hygiene indicators but also in animal-based indicators such as hyperthermia or hypothermia, highlighting the need for further evaluation of quality criteria in dairy calf welfare assessments. Nevertheless, animal welfare assessments by farmers themselves could be useful tools to sensitize farmers to animal welfare and thereby improve calves’ welfare. 相似文献
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Summary Genotype x year (G x Y) and genotype x crop (G x C) interactions may be confounded in sugar cane when data is obtained from the plant crop and/or from ratoon crops in successive years. A technique to minimise the effects of confounding of the G x C interaction with the G x Y interaction is presented. The mean yield of cane from neighbouring farms was used as an indicator of the year (environment) effect. It was used to re-analyse yields from three experiments comparing six genotypes grown over a plant crop and three ratoons. Two experiments were grown under rainfed conditions and one experiment was irrigated. The confounded interactions were partitioned into a linear contrast on the farm yields (a year effect) and a crop effect that was the remainder. When the yields adjusted for the farm yield effects were compared with original yields of cane, yields of plant and first ratoon were reduced and those of third ratoon were increased. There were only minor changes in the ranking of genotypes on yield. It was concluded that the re-analysis using farm yield showed that the confounding effect of years on the interpretation of genotype x crop effects was samll. 相似文献
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