The Research Column

Fresh whey cheeses are susceptible to the growth of mainly moulds and yeasts, due to their high moisture, protein and lactose contents, low salt concentration, and pH around 6.0. Even with good hygienic practices and effective cooling, they have limited shelf life. Thus, the investigation of post-production decontamination methods, preferably alternatives to thermal and chemical treatments, is required to ensure the safety and quality of whey cheeses during delivery and storage.

Genetics are inextricably linked to reproductive physiology and performance of dairy cows. In this context strong associations have been reported for genomic enhanced PTA for fertility and reproductive outcomes (PTA meaning the predicted difference of a parent animal’s offspring from the average, due to genes transmitted from that parent).

Milk is a valuable source of nutrients in human nutrition, but the composition could be altered as a result of physical interventions. Due to safety requirements, shelf life and consumer preferences, milk is normally pasteurised, homogenised and sometimes spray dried. Homogenisation is done using pressure and heat, and this causes changes in the location of proteins in the milk as well as protein modifications which can affect nutritional characteristics. The intention of the study cited was to investigate these proteomic changes further and to what extend they are variable.

Methane is a greenhouse gas which because of climate change expectations should be mitigated. Its production in the rumen also results in 4 to 12% loss in potential energy to the cow, and therefore mitigation may improve production performance, at least theoretically. There are several feeding and management strategies to exploit methane mitigation, and more recently genetic variability, which is the subject of this investigation, has also been explored.

Mastitis worldwide is arguably the most important disease of dairy cattle and thus far only cured with antibiotic administration. With antimicrobial resistance (AMR) the focus has shifted to reduce antibiotic treatment with emphasis being put on optimization at herd level and treatment only through evidence-based cases. Currently, an accepted treatment is through a combination of local intra-udder and systemic treatment with penicillin in terms of the bacteriological cure of mild and moderate clinical mastitis cases caused by gram-positive organisms.

Globally, unhealthy diets have been recognised as a major cause of death and cardiovascular disease (CVD). Limitations to these reports include recommendations based on associations of individual foods, or nutrients or dietary patterns with CVD, and from studies conducted mostly in North America, Europe and East Asia, and otherwise numerous short-term randomized intervention trials of physiologic risk factors or clinical trials of dietary patterns on clinical outcomes.

In pasture systems, milk production is aimed to be maximised from grazed pasture with merely minimum supplementation to meet dairy cow requirements when necessary. The economic impacts of increased pasture production and utilization on farm profitability is well known, but the influence of maximising utilisation in different circumstances is not always known, one being soil type.

It is accepted that the best economic results, informed by the yearly peak milk, is a one-year calving interval (CI), which includes a 10-month lactation and a two-month dry period. However, as a consequence of this cycle, cows experience several transitions during the year, including drying-off, calving and the start of the next lactation. During these transitions, large changes in both physiology and management are associated with an increased risk of diseases and disorders, such as clinical mastitis, milk fever and ketosis.

The transition period in dairy cows imposes metabolic challenges that often reduce milk production and reproductive efficiencies. Energy, nutrients and oxidative balances are often compromised during this period, resulting in impaired immunity, increased susceptibility to disease, thereby further compromising nutrient intake and partition. Health problems and extensive mobilization of body reserves after calving have enduring effects on reproductive performance.

It has been known for more than 50 years that rumen bacteria can convert NPN sources into bacterial protein which can then be utilised by the ruminant. The advantage of the conversion is that NPN sources are cheaper than true protein supplements. There are however two issues which should be considered: (1) urea as the major NPN sources may be toxic at high levels, and (2) it has been shown that at high milk yields, microbial protein is limiting in certain amino acids, which then have to be supplemented by protein sources with rumen-bypass characteristics.