Considering the culling reasons and trend of its changes Using 16 years data of mega dairy Holstein farms in Iran

Document Type : Research Paper

Authors

• Saeid Mokhtarzadeh Dilmaghani ¹
• Mohammad Reza Sanjabi ²
• Abdolreza Salehi ³

¹ Department of Animal Science, Agriculture Research Institute, Iranian Research Organization for Science & Technology(IROST),Tehran, Iran

² Department of Animal Science, Agriculture Research Institute, Iranian Research Organization for Science &; Technology( IROST), Tehran, Iran

³ Department of Animal and Poultry Science, Abureyhan College of Agricultural Technology, University of Tehran, Tehran, Iran

Abstract

Keywords

• Culling reasons
• Trend of culling changes
• Industrial Holstein Mega Farms

Main Subjects

• Animal Breeding and Genetics

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 1^st, 2^nd, 3^rd, 4^th,and 5^th 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.