Dairy R&D in SA

Antimicrobial resistance (AMR): The results of an antibiotic susceptibility testing trial of Staph. aureus isolates showed that 75-80% isolates were multidrug resistant. The isolates were found to be 100% resistant to amoxicillin, ampicillin and penicillin G, 95% resistant to cephalexin, 82% resistant to streptomycin, 75% resistant to oxacillin, 64% resistant to erythromycin, 50% resistant to tobramycin, 46% resistant to tetracycline and 39% resistant to vancomycin. None of the Staph.

Coagulase negative Staphylococcus or non-aureus Staphylococcus (CNS/NAS) pathogens are relatively new isolates affecting udder health. The most common strains isolated from a study on 20 SA dairy herds were Staph. chromogenes, Staph. epidermidis and Staph. haemolyticus. The numbers of the CNS/NAS strains increased as lactation progressed.The results were also evaluated to identify a probable correlation between the CNS/NAS strains and somatic cell count (SCC) levels. Staph.

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.

Milk flocculation and gelation describe the phenomena relating to protein instability that could lead to the rejection of milk for processing or to defects in long-life milks such as UHT milk. The term flocculation which is the topic here, applies to the protein precipitate that is formed in the test tube when ethanol unstable milk is subjected to the Alizarol test.  The ethanol concentration in the test varies from 68% to 76% ethanol and milk that flocculates is then declared unfit for further heat processing and rejected.

Important on-farm management factors: In a study1 done in 2014, the relative importance of different variables was investigated. The principle was to change one variable by one unit while keeping the others constant, and then to see what is the effect on profitability. The results, which I have averaged to limit the effect of milk buyers who differ in their payment schemes, are presented in the table for TMR and pasture-based systems.

Table: Economic values (R per unit) for TMR and pasture-based production systems

Introduction: The world has changed as the evidence and perceptions about climate change have surfaced and progressively became centre in the media and people’s minds. This has lead to questions of what are the reasons for the change which primarily pointed fingers to man-introduced carbon emissions and over-use of resources and waste accumulation. All sectors, including agriculture (therefore dairying), have come under scrutiny.

The Covid-19 pandemic has resulted both in shifts in South Africans’ demand for dairy products as well as changed purchasing habits according to BMi Research, cited below.

The impact of mastitis is significant and costly. Mastitis leads to economic losses to both the farmer and processor, welfare implications for the cow and antimicrobial resistance concerns. Describing and analyzing the measures used to prevent this disease and to minimize the losses is important from an economic perspective. In evaluating the economics of managing mastitis, farmers need to take into account losses incurred subsequent to the disease (failure cost, FC) and those invested to prevent the disease (preventive cost, PC).

There are several causes of hepatogenous or secondary photosensitisation in ruminants in South Africa, e.g. hepatotoxic plants, water-borne cyanobacteria, the mycotoxin, sporidesmin, found in spores produced by the saprophytic fungus Pithomyces chartarum etc. In cattle, hepatogenous photosensitivity associated with the feeding of crops comprising certain cultivars and/or hybrids of forage Brassica, namely turnip (Brassica rapa ssp. rapa), rape (B. napus ssp. biennis) and swedes (rutabaga, B. napus ssp. napobrassica) has been reported from Australia  and New Zealand.

The peripartum period comprises the last three weeks of gestation to three weeks after calving. During this period, many adaptations occur in preparation for calving and the onset of lactation. These are of endocrine, metabolic and immunological nature and include increases in circulating concentrations of oestrogen, non-esterified fatty acids and beta-hydroxybutyrate, and reduced serum concentrations of progesterone, calcium, glucose, insulin and insulin-like growth factor 1.