Dairy R&D in SA

In recent years, there has been an increase in the prevalence of environmental pathogens as a cause of within udder infections in dairy cattle. Increases in prevalence could potentially be ascribed to improved control methods for contagious pathogens, difficulties in controlling pathogens from an environmental reservoir and the ability of Streptococcus uberis and Escherichia coli to persist in the udder. Streptococcus uberisshowed an increase in prevalence over an 11-year study period (1996–2007) in South African dairies.

 Author: Heinz Meissner, Milk SA Program Manager R & D, November 2018.   

1. Mastitis Program:

1.1. PRJ-0210 Antimicrobial resistance on dairy farms - Screening mastitis causing coliforms for the production of extended spectrum Beta-lactamases and Colistin resistance. Dr Inge-Marie Petzer.

Ideally, pasture management should emphasize production of optimum forage yield and quality, without compromising the environment. Accurate irrigation scheduling, therefore, plays an important role in the success of a dairy enterprise by affecting forage yield and quality, irrigation input and energy usage, and environmental pollution. For years farmers arbitrarily have used an irrigation guideline of 25 mm of irrigation water per week for most temperate grasses and legumes, regardless of season or region.

The South African dairy industry shows immense diversity when it comes to mastitis management practices. However, if consistently executed, which should improve udder health and milk flow, it could be satisfactory, but supporting the diversity by extension is a challenge. As is the case globally, the dairy industry is aware of and actively addressing antimicrobial resistance (AMR). To that effect, a survey was funded by Milk SA to record what practices are followed and a project: ‘Resistance to Available Antibiotics in Lactating Cows with Mastitis’, was initiated in 2015.

Dairy farms often experience a summer through autumn rise in somatic cell count (SCC) with some farms affected more than others.  The extent to which climatic factors contribute to this summer rise in SCC in South Africa is unknown although weather is blamed anecdotally. Consequently, the value of heat abatement or other preventative intervention cannot be established. The relative effect of season and/or heat stress on milk production and SCC is likely to be unique to South African conditions and therefore this formed the basis of the study cited below.

The dairy industry is a major consumer of antibiotics globally and mastitis is the most treated disease of dairy cows. In South Africa, producers have unrestricted access to 12 of 22 registered within-udder antibiotic products without prescription, whereas the remaining 10 registered products are restricted for veterinary use. It is conceivable that the antibiotics available without prescription may be used incorrectly and may contribute to the emergence and/or persistence of antibiotic-resistant strains. 

The sustainability of current nitrogen (N) fertilization regimes for minimum tillage kikuyu-ryegrass (Pennisetum clandestinum, Lolium multiflorum) pastures in the southern Cape is questioned. The guidelines, originally, were developed for conventional tillage and non-grazing systems. It may well be that these guidelines may not apply any more. In fact, there is the possibility that the N levels applied are too high with implications to both economics and leaching of unutilised N.

The forage herbs chicory (Cichorium intybus) and plantain (Plantago lanceolata) have become regular components of south-eastern seaboard dairy pastures. They are mostly planted in a mixture with grasses and often clover species are added as a minor component. How they do and what benefits they bring to the pasture mix and the cow have not been well researched in these areas. This was then the purpose of the trials cited below. 

The Dairy Sustainability framework (DSF) of the IDF proposed that the Baseline for the global dairy sector should be set at the FAO (2013) figure of 2.9 CO2 eq per kg of fat and protein corrected milk (FPCM). It is accepted that different countries will vary substantially as GHG emissions are influenced by milk yield, feeding practices and efficiency of production. Thus, the figure for some developed country industries is as low as 1.6 CO2 eq per kg FPCM, whereas the figure of Sub-Saharan Africa is 9.0 CO2 eq per kg FPCM.

Discipline: grazing/pastures; Key words: cultivated pastures, fertilisation, nutrient cycling, phosphorus, soil fertility