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Cow longevity and culling on China dairy farms from 2013 to 2015.

S. Liu




Cow longevity and culling on China dairy farms from 2013 to 2015.
S. Liu*, J. Ma, Z. Cao. China agricultural university Beijing, China.

Few data are available on the descriptive characteristics of cow longevity and culling within a national population in China. The objective of this study was to describe cow longevity and the reasons associated with culling on dairy farms with more than 100 cows across China. In 2016, a nationwide survey was conducted, and 100 dairy farms in 12 provinces were involved. Culling records and the related data were obtained from management software and report system. Data were analyzed using SAS (version 9.0, SAS Institute Inc., Cary, NC, USA). Culling refers to the exit of cows from farms, as a result of death but regardless of reason, and cow-culling rate was calculated as the number of mature cow exits each year divided by the mean of mature cows stocked in the same year. The results showed that from 2013 to 2015, average culling rate were 24.7%, 22.9% and 30.4%, and average lactation age were 2.5, 2.7 and 2.9, respectively. 72% of culls were from the first 3 lactations, and the highest proportion of culls occurred in second lactation, accounting for 26.2%. Days in milk had effect on culling rate (P < 0.01), and most culling occurred before 60 d in milk, accounting for 27%. The causes of culling were also different (P < 0.05) with reproduction related reasons accounting for 20.9%, followed by digestive related reasons (20.7%), udder related reasons (13.7%), hoof related reasons (8.5%) and unknown reasons (8.4%). Voluntary culling accounted for 11.4%. In addition, the lactation age was affected by causes of culling (P < 0.01). Cows with reproductive diseases and respiratory diseases usually were culled in first 3 lactations, while cows with digestive system disorders, metabolic diseases, hoof diseases and udder diseases were often culled in higher lactation age (4—6 lactation). Culling rate was also related to farm scale(P < 0.01). Dairy farms with 100 to 500 cows had the highest culling rate (32.9%), followed by dairy farms with 500 to 1000 cows (30.7%), dairy farms with 1000 to 2000 cows (27.5%), and dairy farms with more than 2000 cows had the lowest culling rate compared with other sale farms (23.4%, P < 0.05). This study provides an overview on dairy cow longevity and culling in China.

Keywords: mature cow, cow longevity, culling rate.

Biography: My name is Shuai Liu, a Ph.D student from China agricultural university. I am interested in calf nutrition and dairy farm management, and I have been involved in several research programs related to butyrate regulation on calves and national survey on China dairy cattle management, several of which are in progress. I have been to the United States and Ireland for internships and trainings. One publication has been published, and one oral presentation and one poster have been presented in 2019 ASAS Annual meeting.