The Research Column

Bacteria are ubiquitous microorganisms present in all known environments, including various areas of the animal body as well as in fermented dairy foods, where they are organized in complex consortia. The microbial ecology of fresh cheese has been extensively investigated, and has lead to the generally accepted understanding that bacteria residing in milk may contribute beneficially to the aroma of fermented dairy products. Here, lactic acid bacteria are particularly important due to their positive or negative impacts on fresh and ripened cheese.

Dairy cattle often experience negative energy balance during the calving transition period, because of reduced feed intake and a drastic increase in nutrient demands after the onset of lactation, thereby contributing to high risk of metabolic disease and low immunity. This implies that feeding strategies during the calving transition period should be designed to maintain feed intake to mitigate excessive fat mobilization.

Some cheeses, including Camembert and related varieties, can be produced by different processes that vary in milk pre-acidification, cutting, curd handling and ripening.  Modification of these creates distinct cheeses such as lactic curd, stabilized curd and hybrids of the two. The objective of the study by Dr D. Batty and colleagues reported below, was to determine the influence of five Camembert-type cheese recipes on   composition and characteristics during ripening.

Due to perceived health reasons, consumers have shown an increasing interest in the consumption of cheese with a lower fat content. One of the main properties of reduced-fat cheeses is a higher protein to fat ratio that results in a more compact structure leading to a firmer and rubbery texture, a lack of flavour, bitterness (unacceptable sensory properties), development of off-flavours, poorer melting properties and a translucent appearance.

Reducing on-farm storage and retail waste should increase agricultural resource efficiency and, thus, food availability. One way of reducing waste and increase efficiency could be to reduce inclusion of human-edible products such as cereal grain (e.g. maize, wheat, oats etc) and soybean meal in the diets fed to dairy cows in intensive production systems.

Consumers complain about spoilage due to bacterial growth and spoilage also contributes to dairy product waste, which in a developing country we cannot really afford. We probably do not have figures in South Africa, but milk spoilage in the US amounts to $6.4 billion per year. Microbial spoilage is of particular concern and can be caused by either psychrotolerant spore formers, which likely originate from raw milk, or by post-pasteurization contamination (PPC).

Increasing input costs and new regulations to reduce nutrient loss have created pressures to improve agricultural nutrient use efficiency. In ruminants, and therefore dairy cattle, the greatest potential to reduce greenhouse gas (GHG) emissions and other environmental pollutants involves improving animal and herd efficiency.

Costs associated with clinical udder infection can be divided into treatment costs, costs of mortality through culling (replacement of culled animals) and indirect costs from production losses. Intervention for clinical cases usually consists of (mainly within udder) antibiotic treatment. However, in light of its connection with antimicrobial resistance, it may be prudent to search for alternative interventions. For instance, culling cows with clinical mastitis could be a viable alternative.

Discipline: breeding; Key words: genomic testing, rate of genetic gain, sexed semen   

Discipline: economics; Key words: dairy system, pasture-based milk production, cost control, profit