Dairy R&D in SA

The most popular dairy breed in South Africa is the Holstein. Being of European origin the Holstein is not well adapted to South African veld conditions. Consequently, its milk production on veld is very low, and the animals cannot subsist and produce without some form of supplementary feed. The Nguni breed is an African breed, and is used by communal farmers in KwaZulu-Natal for household milk supply.

Recent research shows that the contribution of methane (CH4) to the atmosphere by shale gas and other earth sources is much higher than accepted in IPCC calculations, which implies that much less is from ruminants (Howarth, 2019). Secondly, in carbon footprint calculations the CO2 capture by photosynthesis through the biogenic cycle in plant foods (say maize) (which apart from CO2 may also have resulted indirectly from atmospheric CH4) is not taken into account (Frankelius, 2020). This is actually a carbon sink.

The main greenhouse gases (GHG) contributing to global warming potential from the agricultural sector are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Nitrous oxide has a 121-year life span in the atmosphere and a global warming potential of 265 times that of CO2, if compared over a 100-year period. This makes the control of N2O from the agricultural sector crucial to assist in mitigation of GHG emissions.

Dairy has been targeted as a source of greenhouse gas emissions. However, research has shown that grazing livestock on pasture-based dairy farms restore carbon to the soil, enhancing its biodiversity and countering climate change. This poses the question: If farms can have a positive impact, but are also a source of negative impact, what is the net effect? This is an important consideration when assessing the negative contribution that dairy farming makes to climate change.

Heartwater is caused by the proteobacterium Ehrlichia ruminantium, which is transmitted by the tick Amblyomma hebraeum.

Fasciola species are liver flukes that infect cattle and reduce the productivity by 15-30%. The infection can affect general health and feed intake that leads amongst others to morbidity, reduction in milk production and weight gains.

Mastitis results in large economic loss to both farmer and processor. In addition it has welfare implications for the cow and antimicrobial resistance concerns. Therefore, describing and analysing the measures used to prevent the disease and to minimize the losses remain important. For example, somatic cell count (SCC) directly affects revenue from the sale of milk and in one of the investigations the revenue loss was studied.   

Conception and re-conception rates of high-producing dairy cows remain of concern in dairy production systems, especially in the subtropics. Apart from the major effects of nutrition and specific nutrients on reproduction, other risk factors such as negative energy balance, inflammation and impairment of the immune response have been shown to affect re-conception rates. Dietary energy levels interact with blood urea nitrogen (BUN) and may influence the pregnancy rates of dairy cows.

Profitable milk production and genetic improvement in dairy herds depend largely on fertile cows calving annually to initiate a new lactation period. Over the last 30 years, several studies have indicated a decline in the reproductive performance of dairy cows. From the perspectives of many farmers and veterinarians, the reproductive performance of cows is related to the calving interval and services per conception.

Discipline: grazing/pastures;