# Cow Longevity and Reasons and Risk Factors for Culling in South African Holstein and Jersey Dairy Herds

## TL;DR

This study analyzed culling reasons and risk factors for South African Holstein and Jersey dairy cows to help improve herd management and reduce economic losses.

## Contribution

The study provides the first detailed analysis of culling patterns in South African dairy herds using nationwide data from 2000 to 2019.

## Key findings

- Infertility, mastitis, and low milk yield were the top culling reasons for both Holstein and Jersey cows.
- Cows calving in summer, those in third parity, and those in small herds had the highest risk of culling.
- Improving fertility and udder health could reduce culling and enhance dairy profitability and sustainability.

## Abstract

Knowledge of culling reasons and the associated risk factors, in dairy herds, is essential for assisting farmers to develop management strategies to minimize economic losses due to involuntary culling. Such knowledge is, however, limited for dairy cattle performing in South Africa. This study examined culling records of Holstein and Jersey cows from 1864 South African herds with complete records from the period of 2000 to 2019. Average productive life of cows was between 2 and 3 lactations. Infertility, mastitis and low milk yield were identified as the most common culling reasons for both Holstein and Jersey cows. Calving season, parity, and herd size significantly influenced the risk of culling, with cows calving in summer, and those in third parity or small herds having the highest risk. Collectively, these culling reasons and risk factors have an impact on cow longevity, herd productivity, and profitability. Strategic herd management practices can be developed based on these findings, with increased focus on improving fitness and functional traits, to enhance cow resilience and ensure profitable and sustainable dairy farming.

This study investigated cow longevity, culling reasons, and risk factors influencing culling in South African Holstein and Jersey dairy herds. Lactation records of 1,150,625 Jersey and 1,534,875 Holstein cows from 1864 herds, recorded through the National Milk Recording Scheme during the period 2000 to 2019, were analyzed. Longevity was calculated as length of productive life and number of completed lactations. Logistic binary regression was conducted to estimate the odds ratios (OR) for culling among different calving seasons, parities, and herd sizes. Holstein cows had mean productive life of 739.33 ± 434.31 days and 2.37 ± 1.08 lactations, while Jersey cows averaged 696.81 ± 415.44 days productive life and 2.47 ± 1.13 lactations. Leading reasons for culling were infertility (37.94 ± 0.48% Holstein; 30.46 ± 0.63% Jersey), mastitis (18.15 ± 0.38% Holstein and 18.16 ± 0.53% Jersey), and low milk yield (11.76 ± 0.32% Holstein and 19.76 ± 0.55% Jersey). Summer calving, third parity, and small herd size had the highest odds of culling. These findings suggest that herd management practices and selection objectives in South Africa should place high emphasis on cow fertility and udder health. Furthermore, cows calving in summer and those in third parity or small herds require particular attention to minimize culling. Such measures may help to reduce involuntary culling rates and thus increase herd profitability as well as dairy industry sustainability.