Dairy R&D in SA

There is not much information on the effect of dietary nitrate addition as a method to mitigate methane in grazing dairy cows. Therefore, the authors cited below did a study aiming to investigate the effect of nitrate addition on daily enteric methane emissions, production performance and rumen fermentation of multi-lactation Jersey cows grazing perennial ryegrass pasture, which contained about 7.3 g nitrate per kg dry matter (DM).

Claw health is an important factor in animal welfare and its evaluation is an early indicator of lameness in dairy cattle. However, claw disorders on many farms are not routinely evaluated and the information not included in genetic evaluations as they are not always considered in terms of productivity. The aim of the study by the authors cited below was to evaluate claw health of dairy cattle housed in dirt lot vs free stall under the TMR systems.

Stillbirth remains a problem in dairy herds in many countries and is increasingly included in national breeding objectives. In South Africa, however, we lack reliable information on the incidence of stillbirth that can be used to improve this trait genetically. Currently, there are no estimated breeding values (EBVs) for any measures of calving performance produced under the national genetic evaluation programmes.

Pseudomonas is a highly competitive bacterial genus that is generally found in the environment.  They also act as opportunistic pathogens of both animals and humans. In the dairy environment it can cause a damaging form of mastitis in dairy cows and is often resistant to a wide spectrum of antibiotics which makes it difficult to treat. Ps aeruginosa, is not a factor in causing spoilage of refrigerated milk due to its high optimum growth temperature.

The severe droughts in successive years in several parts of the country have suggested that more regular droughts and water shortages could become the norm in future farming. This, of course, is also predicted by climate change scientists and it implies that farmers will have to look at ways to make the most of the water they have. Soil management, rainwater harvesting and proper storage of water will determine how efficiently farmers make use of water resources.

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.

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.

The response of pasture yields to nitrogen (N) fertilization is a long-standing topic of debate. In dairy-pasture systems, N application is often thought to be directly proportional to pasture yield. The question is: is it. This was evaluated using data from 153 pasture camps over five years. Fertilizer application rates were grouped into three treatments: <200, 200-350 and >350 kg N per hectare (ha) and the herbage yield response over the five years was recorded.

Age gelation is a process in which there is formation of a three-dimensional protein network within UHT milk which occurs during storage, and is marked by increasing viscosity before observable gelation. In South Africa, the dairy industry loses millions of Rands annually as a result of the condition in UHT milk. As such, there is a need to study and evaluate the possible correlation of variables that may contribute to the occurrence of age gelation in UHT milk.

Discipline: nutrition/feeding;