The Research Column

Technological advancements allow dairy farmers to increase the efficiency of use of land, labour, and capital to produce milk. Automatic milking systems (AMS) offer the possibility to increase productivity and profitability by potentially improving labour efficiency, milk production, animal welfare, and lifestyle.

To try and improve the efficiency of protein use in dairy production has been the goal of many studies in the past 40 years. Lower dietary protein with the same milk protein output should increase protein efficiency and profitability. However, reduced production is a potential risk of feeding diets with less protein, as feeding less protein may reduce the energetic and economic efficiency of producing milk. Thus, the challenge is to identify ways to feed less protein while maintaining or enhancing milk production.

Up to 90% of administrated antibiotics are eliminated from the animal body through the faeces or urine, implying that manure generated from animal production represents a major route of antibiotic transfer to the environment. The presence of antibiotics, even at very low concentrations, can contribute to emergence of antibiotic resistance genes (ARG) and selection of antibiotic resistant bacteria.

The environmental effects of mineral nitrogen are of global concern, and there is growing determination to mitigate its use for agricultural purposes. The replacement of synthetic fertilizer N with N fixed by bacteria (biological N fixation) in association with legumes such as white clover (Trifolium repens L.) offers the potential to lower fertilizer N use, nitrous oxide and ammonia emissions, and energy use.

Below par post-calving health has a negative effect on the performance and survival of dairy cows and occurrence of uterine, metabolic and other health disorders which are risk factors for lower subsequent fertility and milk yield, and higher risk of culling. The interrelationship between loss in body condition score (BCS) and disease prevalence is however complex and establishing cause and effect associations is challenging. Increased risk of milk fever, ketosis, fatty liver, metritis, digestive disorders and mastitis in cows with greater loss of BCS after calving has been shown.

In the study, the effects of homogenization conducted at higher pressure than the conventional (10 megapascal [MPa] for the first stage and 5 MPa for the second stage) on curd structure of set yogurt was investigated, the focus being on the fat globule size. Each yogurt mix was adjusted at the range of fat globule sizes from 0.45 μm to 1.1 μm by a homogenizer and then heated at 95°C for 5 minutes (conventional heat treatment), 120°C for 2 seconds (ESL processing) or 140°C for 2 seconds.

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.