The Research Column

Studies evaluating RFI divergence between dairy cows have usually been performed during established lactation. Whether shortening the feeding period and increasing the number of cows would enhance the ability to detect physiological differences between the most efficient and  least efficient cows is largely unknown.

Cheese production is from fermentation processes by starter cultures used to generate lactic acid enabling gel syneresis, whey expulsion, and curd formation. Natural whey cultures (NWC) are undefined cheese starters obtained by the traditional back-slopping procedure. They play a key role in cheese specificity, uniqueness, and development of sensory characteristics.

Methane emissions and rumen fermentation characteristics of the dairy cows fed 100% plantain (PLT) or 100% perennial ryegrass (RG; Lolium perenne) were measured in two experiments (E1 and E2). The forages were in a vegetative growth stage in E1 and were in a reproductive growth stage in E2. The CH4 emissions from 16 cows in each experiment were measured in respiration chambers for two days.

Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 days before their expected calving date. Both groups received the same diet, except for the source of trace minerals (TM). The STM group was supplemented with Co, Cu, Mn and Zn sulfates and Na selenite, whereas the OTM group was supplemented with Co, Cu, Mn and Zn proteinates and selenized yeast.

The study used 2616 calves entering a calf-rearing facility for veal calves in Canada. The results nevertheless are considered relevant to rearing of heifer calves on farm. Faecal consistency scores were assigned twice daily for the first 28 days following arrival, where a score of 2, indicating runny consistency, and 3, indicating watery consistency, were classified as diarrhoea. Severe diarrhoea was classified by a score of 3. Serum total protein was measured upon arrival and the source of the calf (i.e., whether the calf came from a calf seller, local farm, or auction) was recorded.

Discipline: starter culture; Keywords: industrial cheese manufacturing, enzymatic coagulation, protein separation, proteolysis.

Miniature cheeses can open up new possibilities to screen cheese starter cultures and study many other aspects of cheese production in the factory. The study was reported by H. Bachmann and coworkers in the Journal of Dairy Science (2009), Volume 92, pages 5868-5882, using the title: A high-throughput cheese manufacturing model for effective cheese starter culture screening.

Discipline: milk powder; Keywords: oxidation, rancidity, off-flavours, light exposure, package atmosphere.

The objective of the study was to establish whether nitrogen flushing and colder than normal storage temperature will be favourable to flavour and shelf life of whole milk powder. This research by Dr M.A. Lloyd and colleagues was published in The Journal of Dairy Science, Volume 92 of 2009, pages 2409 to 2422. The title of the paper is: Effect of nitrogen flushing and storage temperature on flavour and shelf-life of whole milk powder.

Discipline: cheese; Keywords: conceive after birth, cheddar cheese, lactation length, cheese yield, organoleptic properties.

Discipline: lactation management; Keywords: once-a-day milking, extensive dairy production systems, labour requirements, pasture deficit.

Discipline: organic production; Keywords: organic cheese, demand, taste panel, willingness to pay, market.