用随机回归模型估计宁夏地区荷斯坦牛头胎测定日产奶量遗传参数

发布时间：2018-06-14 10:11

本文选题：测定日产奶量 + 遗传参数　；参考：《中国农业科学》2017年10期

【摘要】：【目的】通过拟合泌乳曲线对影响宁夏地区荷斯坦牛测定日产奶量的诸多因素进行分析,并采用随机回归测定日模型估计遗传参数,为后续估计乳成分和体细胞数遗传参数及个体育种值估计奠定基础,同时也为制定适合该群体的优化育种方案提供参数。【方法】收集了2009—2013年间,宁夏地区24个牛场38 592头荷斯坦牛原始DHI数据,共包含550 078条测定日产奶量记录。质控标准为:产犊月龄为22—36 mo、泌乳天数为5—305 d及日产奶量为5.9—53.3 kg。质控后,共得到14 320头母牛的127 478条测定日记录(占原始记录的23.14%)。将有表型的母牛至少向上追溯三代(父母、祖父母、外祖父母),得到遗传评估所用的系谱文件,共包含24 272头奶牛。使用Excel 2013计算各测定日的平均产奶量,利用SAS 9.1软件的非线性回归过程(NLIN)结合Wood模型拟合群体水平的泌乳曲线。采用随机回归测定日动物模型,通过DMU 5.2软件对头胎产奶量进行遗传参数估计。随机回归测定日模型中包括了一般固定效应、固定回归项及随机回归项三类效应。研究中使用场-测定日作为固定效应、产犊年季效应作为固定回归项,并将加性遗传效应和永久环境效应作为随机回归项。测定日子模型采用4阶勒项德多项式(Legendre polynomials)。根据宁夏地区气候特点,将产犊季节划分为春(3月11日至5月20日)、夏(5月21日至8月25日)、秋(8月26日至10月15日)和冬(10月16日至3月10日)四季。【结果】宁夏地区荷斯坦牛头胎测定日产奶量群体均值为29.66 kg,在泌乳90 d时达到泌乳高峰,高峰产奶量为31.84 kg。通过不同产犊年份、产犊季节和牧场效应组合下的泌乳曲线拟合效果分析,以上因素通过影响泌乳曲线拟合效果进而影响头胎产奶量。在使用测定日模型估计头胎遗传参数时均应通过子模型拟合考虑其泌乳曲线的差异,在产奶量遗传评估模型中予以考虑。产奶量性状5—305d的遗传力在0.08—0.29之间,305d产奶量的总遗传力为0.16。【结论】通过使用wood模型拟合宁夏地区荷斯坦牛头胎泌乳曲线,优化了适合于该群体的测定日模型。利用修改后的测定日模型,估计了宁夏地区荷斯坦牛测定日产奶量的遗传参数。305 d遗传力(0.16)略低于其他群体的同类文研究结果。在测定日模型评估生产性能记录时,应注意对残差方差的处理并关注构建分子亲缘关系矩阵所需系谱的完整性,以保证遗传评估的可靠性。本研究为日后使用多性状随机回归测定日模型估计泌乳性状遗传参数研究奠定了基础。
[Abstract]:[objective] to analyze the factors influencing the daily milk yield of Holstein cattle in Ningxia by fitting the lactation curve, and to estimate the genetic parameters by using the random regression model. To lay the foundation for subsequent estimation of genetic parameters of milk composition and somatic cell numbers and individual breeding values, and to provide parameters for the formulation of optimal breeding schemes suitable for this population. [methods] the period 2009-2013 was collected, The original DHI data of 24 Holstein cattle in Ningxia included 550078 daily milk production records. The quality control standard is: the calving age is 22-36 moths, the lactation days are 5-305 days and the daily milk yield is 5.9-53.3 kg. After quality control, a total of 127,478 daily records of 14 320 cows were obtained (23.14% of the original records). The phenotypic cows will be traced back to at least three generations (parents, grandparents, grandparents) to obtain genealogical documents for genetic assessment, containing 24,272 cows. Using Excel 2013 to calculate the average milk yield of each day, the non-linear regression process of SAS 9.1 and Wood model were used to fit the lactation curve at population level. A random regression method was used to estimate the genetic parameters of milk yield of first fetus by DMU 5.2 software. The daily model of random regression includes three kinds of effects: general fixed effect, fixed regression term and random regression term. Field-measurement days were used as fixed effects, calving annual and seasonal effects as fixed regression terms, additive genetic effects and permanent environmental effects as random regression terms. The date model was determined by using the 4 th order Legendre polynomialsm polynomial. According to the climatic characteristics of Ningxia, Calving seasons were divided into spring (March 11 to May 20), summer (May 21 to August 25), autumn (August 26 to October 15) and winter (October 16 to March 10). The average daily milk yield was 29.66 kg, which reached the peak at 90 days after lactation. The peak milk yield was 31.84 kg. By analyzing the effect of lactation curve fitting under different calving years calving season and pasture effect the above factors affect the milk yield of first fetus by influencing the fitting effect of lactation curve. The difference of lactation curve should be considered by submodel fitting when estimating the genetic parameters of the first fetus using the measurement day model, and it should be considered in the genetic evaluation model of milk yield. The heritability of milk yield in 5-305 days was 0.08-0.29. The total heritability of milk yield was 0.16. [conclusion] by using wood model to fit the lactation curve of Holstein's fetal milk in Ningxia area, the suitable daily model for this population was optimized. Based on the modified daily model, it was estimated that the genetic parameter .305 d heritability of Holstein cattle in Ningxia region was slightly lower than that of other populations. In order to ensure the reliability of genetic evaluation, we should pay attention to the processing of residual variance and the integrity of pedigree needed to construct molecular kinship matrix. This study laid a foundation for estimating the genetic parameters of lactation traits by using multiple traits random regression daily model in the future.
【作者单位】：中国农业大学动物科技学院;河南省奶牛生产性能测定中心;宁夏回族自治区畜牧工作站;宁夏四正生物技术工程研究中心;
【基金】：宁夏自治区农业育种专项-《优质高产奶牛育种》项目现代农业(奶牛)产业技术体系建设专项资金(CARS-37)
【分类号】：S823

【相似文献】