Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of ...Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of records of 2496 Chinese Holsteins first lactation cows collected from 1989 to 2000.The model included 21 herd effects,four calving season effects,nine age at first calving effects,6697 animal effects.(Co)variance components of milk yield,fat yield and age at first calving were estimated with the software package for variance component estimation(VCE) by an animal model. The heritabilities were 0.14,0.21,0.38 for milk yield,fat yield and age at first calving,respectively.The estimates of genetic correlation between milk yield and fat yield,age at first calving were 0.96,-0.29,respectively.The estimate of genetic correlation between fat yield and age at first calving was -0.28.展开更多
The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 t...The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 test-day records about 155 893 Chinese Holstein dairy cows collected by the Henan Dairy Herd Improvement Center from January 2008 to April 2016, the dynamics of test times during a complete lactation, test interval during a complete lactation, days in milk （DIM） of first test-day record, daughter descendant number and herd number of bull, age at first calving and pedigree integrity rate among different years and different herd sizes were analyzed by MEANS order of SAS 9.4. In addition, the data that were applicable to genetic evaluation were screened by SQL program. The results showed that during 2008-2015, the number of cow individuals participating in DHI in Henan Province increased from 7 379 to 93 706; the test-day milk yield increased from 19.91 to 24.05 kg; the somatic cell count reduced from 411.09×10^3 to 277.08×10^3 cells/ml; the percentage of cows with DIM ranging from 5-305 d reached 70.92%; the average test times increased from 3.20 to 6.31 times; the test interval decreased from 70.22 to 33.83 d; the dairy cows with age at first calving of 25 months were dominant, accounting for 12.57%; the bulls whose daughter descendant number was 20 or more and the daughters were distributed in 10 or more farms accounted for 6.05%; the one-generation pedigree integrity rate was 82.54%; the percentage of data that could be used for genetic evaluation was screened as 20.67%, which was lower than the results of other similar studies.展开更多
文摘Genetic parameters for milk,fat yield and age at first calving of Chinese Holsteins in Heilongjiang were evaluated using multiple trait restricted maximum likelihood procedures with an animal model.Data consisted of records of 2496 Chinese Holsteins first lactation cows collected from 1989 to 2000.The model included 21 herd effects,four calving season effects,nine age at first calving effects,6697 animal effects.(Co)variance components of milk yield,fat yield and age at first calving were estimated with the software package for variance component estimation(VCE) by an animal model. The heritabilities were 0.14,0.21,0.38 for milk yield,fat yield and age at first calving,respectively.The estimates of genetic correlation between milk yield and fat yield,age at first calving were 0.96,-0.29,respectively.The estimate of genetic correlation between fat yield and age at first calving was -0.28.
基金Supported by Science and Technology Open Cooperation Project of Henan Province(162106000017)Science and Technology People-benefiting Plan Project of Henan Province(152207110004)Puyang Science and Technology Plan Project(150109)~~
文摘The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 test-day records about 155 893 Chinese Holstein dairy cows collected by the Henan Dairy Herd Improvement Center from January 2008 to April 2016, the dynamics of test times during a complete lactation, test interval during a complete lactation, days in milk （DIM） of first test-day record, daughter descendant number and herd number of bull, age at first calving and pedigree integrity rate among different years and different herd sizes were analyzed by MEANS order of SAS 9.4. In addition, the data that were applicable to genetic evaluation were screened by SQL program. The results showed that during 2008-2015, the number of cow individuals participating in DHI in Henan Province increased from 7 379 to 93 706; the test-day milk yield increased from 19.91 to 24.05 kg; the somatic cell count reduced from 411.09×10^3 to 277.08×10^3 cells/ml; the percentage of cows with DIM ranging from 5-305 d reached 70.92%; the average test times increased from 3.20 to 6.31 times; the test interval decreased from 70.22 to 33.83 d; the dairy cows with age at first calving of 25 months were dominant, accounting for 12.57%; the bulls whose daughter descendant number was 20 or more and the daughters were distributed in 10 or more farms accounted for 6.05%; the one-generation pedigree integrity rate was 82.54%; the percentage of data that could be used for genetic evaluation was screened as 20.67%, which was lower than the results of other similar studies.
