World Milk Day on 1 June is an opportunity to recognise the contribution of millions of dairy cows and farmers to our health and livelihood. The intensive nature of dairy production, the increase in average temperatures, more frequent droughts and limited water resources associated with climate change are some of the challenges faced by this industry. These factors can directly and indirectly affect the efficiency and sustainability of dairy production and therefore important to be addressed in research.

The Department of Animal Sciences at the University of Pretoria (UP) has a 100-year-old experimental farm with a dairy unit consisting of 100 South African Holstein herd, with 70 cows in milk – and its research projects are seeking to address some of the challenges faced by the South African dairy industry.

Local dairy farmers are among the top producers in the world, with more than one producer on the world list for exceptional production with regard to average milk production and milk solids. In fact, in a recent publication by Beca (2020) in the Australian Agribusiness Perspectives (23), (in press), the competitiveness and efficiency of South African dairy producers were ranked alongside the five major dairy export countries in the world: New Zealand, USA, Australia, Argentina and Uruguay.

The average growth rate in milk solids production over the past 16 years in SA is the second highest, at 3.7%; Uruguay placed first at 4.5%. South African milk producers were also the highest ranked for profitability expressed as returns on total capital, and the country has shown to be the most efficient in using dairy pastures among these countries – this can be attributed to an industry focus on improving dairy pasture production with optimal utilisation of farm areas under irrigation.

In 2018/19, the local dairy industry produced 3.3 billion litres of milk with a turnover of about R15 billion. The South African dairy cow population consists of approximately 600 000 cows, with an average herd size of 354 cows.  The trend is towards larger farms and herd sizes, and towards large farms converting to cow housing systems in an attempt to alleviate the impact of heat stress on production and reproduction.   These farms have zero grazing systems – where the cows in milk receive most of their feed as premixed rations. Dairy farms contribute to more than 30 000 employment opportunities for farmworkers alone with several more in the dairy value chain, including animal scientists and veterinarians.

Research projects

UP’s dairy unit plays a major role in the practical training of UP animal and veterinary students, who have the opportunity to gain hands on experience on different aspects of dairy farming, including feeding, the reproduction process and aftercare, milking procedures and general health care. 

The unit is managed as a zero grazing system, so the cows in milk receive most of their feed as a premixed ration, while dry and transition cows have access to pastures. The parlour is fitted with a herringbone system with a capacity for 10 cows at a time with automatic cow identification, milk recording and cluster removal. The dairy uses semen from tested sires and follows a selection programme to achieve the breeding objectives for a good yield and a focus on longevity traits to ensure sustainable production.

Several projects are linked to the unit, where diets are studied using feed additives to investigate the effect of improving the efficiency of nutrient utilisation, immune status and overall digestion in the ruminal tract.

The current trend is for an improved understanding of the rumen microbiome; studies have been conducted on bacterial amino acid profiles to improve the duodenal amino acid profile and the potential changes in the rumen microbiome. The rumen is a dynamic system, and precision diets and feeding regimes will dictate the future of sustainable dairy production.

Furthermore, new varieties of pastures such as plantain are being studied as an environmentally friendly alternative with less greenhouse-gas emission.

Heat stress suppresses the immune system of the dairy cow, which results in higher susceptibility for mastitis (inflammation of the mammary gland or udder), lower fertility and milk yield. Nutrition experts in the department are collaborating with the Outeniekwa research farm near George where data is being collected on the various pastures. 

The role of strategic supplementation of trace minerals in boosting the immunity of cows under heat stress is also being investigated, and an interdisciplinary study is being conducted based on historical and current climate data and milk data to demonstrate the effects of climate change on dairy production. The availability of specific parameters can assist with the prediction of milk yield under changing climatic conditions. This is essential research to ensure long-term viable dairy production in South Africa.   

For decades, dairy cows around the world have been selected for maximum milk yield and milk solids; this has had a negative effect on fertility, locomotion and mastitis incidence. These traits, however, determine the longevity or lifetime production of the cow, and over the past decade, dairy breeders have shifted the selection focus to improving traits associated with longevity and the general health and welfare of the cow.

A PhD student in the Department of Animal Science is searching for the genomic regions in the cow genome that can be associated with resistance to mastitis. In this study, a genome-wide association study will be performed to gain insight into the underlying genetic mechanisms of claw traits. Sound claws are essential as these influence the cow’s ability to walk. Claw lesions and poor claw health result in lame cows, with a direct effect on cow longevity, milk production and the general welfare of the animal.

Two studies are linked to this research: one that focuses on estimating genetic parameters for cow claw traits; the other will be conducted at the UP dairy on the early detection of lameness in collaboration with the Department of Electrical, Electronic and Computer Engineering. Sensory technology will be used to monitor cow movement for early prediction of claw problems, which can improve claw management and prevent cows from becoming lame.  

The unit is also investigating the concept of cow comfort, which takes all aspects of the animal’s daily routine into account: the housing of the cow, the time she has available to lie down and ruminate, her walkway to the dairy parlour, and her experience during milking. In this study, the time budget of the cow is studied and includes the use of music in the milking parlour for stress relief. These projects are all aimed at improving cow comfort and sustainable production by using automated video and sensory technology. It is envisaged that this research focus can contribute to precision farming and the general health and welfare of dairy cows in South Africa.

Opinion piece by:
Professor Este van Marle-Köster
Head of the Department of Animal Sciences at the University of Pretoria (UP).  
Her research focuses on the application of DNA markers and genomic information in the genetic improvement of livestock for sustainable production.