نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دامی، پژوهشکده کشاورزی ، سازمان پژوهش های علمی و صنعتی ایران تهران، ایران
2 گروه علوم دامی، پژوهشکده کشاورزی، سازمان پژوهش های علمی و صنعتی ایران-تهران،ایران
3 گروه علوم دام و طیور، دانشکده فناوری کشاورزی (ابوریحان)- دانشگاه تهران، تهران، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Cow culling is one of the main economic aspects in mega-dairy cattle farms management. Therefore, in this research the cow culling reasons in 20 Iranian industrial Holstein mega-dairy farms during the last 16 years (2005 -2021 years) was considered. A total of 129454 cows data were used to analyze by T-Student methods of SAS software version 9.4. Based on the culling reason, data were classified into 11 classes. The annual culling rate of the milking cows was approximately 23.5%. Predominant reasons for culling were fertility problems and abortion (23.7%), metabolic and digestive disorders (15.8%), and infectious disorders (15.6%). The investigation of the trend of culled cows showed that fertility problems and abortion increased from 22.0% in 2005 to 24.6% in 2021. Also, culled cow’s percentage for metabolic and digestive disorders decreased (from 24.0% to 13.0%) and the culling percentage in year 2021 significantly differed from the average of the past 15 years, also feet/claw disorders (P<0.01) and Infection diseases (P<0.01) were significantly higher than the average of the past 15 years. It means that in the final year of the report, the culling of cows due to metabolic and digestive problems as well as udder disorders decreased compared to the 16-year averages, voluntary culling did not increase or change, but the culling percentage due to infectious diseases and lameness was increased. Increasing trend of voluntary culling can be improved by improving fertility and preventing abortion, along with decreasing slaughter culling of lameness and infectious diseases, and ultimately increase herd profitability.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
Cow culling is one of the main economic aspects in large industrial dairy cattle farms. In this study the main culling or death reasons of cows were considered in aim of prepare adequate knowledge for better management of problems in herds. Culling is typically divided into two types, optional and non-optional (mandatory cull) with different economic losses. Considering that knowing the main causes of culling in dairy herds and what changes they have had in recent years play a fundamental role in finding a suitable strategy to have more profitable and less problematic cows. This study was designed and carried out to find culling reasons and their changes trend across years.
Materials and Methods
The data of 129454 culled cows from 20 industrial mega Holstein dairy farms located in 14 provinces in Iran during the last 16 years (2006-2021) were analyzed using SAS software (version 9.4) and T-Student test. All herds used the same herd management software system with the same herd information entry mechanism, which minimized the amount of outlier data. The average herd size was 2069 cows (max: 5301, min: 400 cows) and the annual culling rate of dairy cows was 23.5%. The average age of the first calving, standard milk production, were respectively 746 days, 12440 kg, and the average age of the culled cows with an average of 996 milking days, was 1884 days. The reasons for culling cows were classified into 11 classes. Number of cow in 1st, 2nd, 3rd, 4th,and 5th lactation were 28305 (21.9%), 27750 (21.4%) , 25321 (19.6%) , 19637 (15.2%) , and 28441 (22.0%) respectively.
Results and Discussion
The main reasons for culling cows included fertility problems and abortion (23.7 %), metabolic and digestive disorders (15.8 %), infectious diseases (15.6 %), feet/claw disorders (12.6 %), arbitrary cull (12.0 %), and udder disorders (8.3 %). Results showed that percentage of cows culled due to fertility problems and abortion in year 2022 didn’t significantly differed from the average of the past 15 years. Feet/claw disorders (P<0.01) and infectious diseases (P<0.01) in year 2022 was higher than the average of the past 15 years but udder disorders (P<0.01) was lower. Metabolic and digestive disorders and udder disorders in year 2022 was significantly lower than average of the past 15 years. It can be concluded that although in the final year of the report, the culling of cows due to metabolic and digestive problems as well as udder disorders decreased compared to the average of past 15 years , but voluntary culling rate did not increase or change, due to increase of culling percentage for infectious diseases and lameness.
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