The Research Column

Discipline: management; Key words:dairy technologies, biomarkers, health, welfare, husbandry, review.

Discipline: hypocalcaemia; Key words: oral calcium bolus, subclinical hypocalcaemia, transition cow.

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.

A fermentation product of the yeast Saccharomyces cerevisiae (SC), has been widely used in diets of dairy cows with the aim of increasing production performance and stabilizing rumen pH. Several studies have reported positive effects such as increased DMI and milk production when cows were fed SC, but the results are inconclusive. Also,  the possible interaction between the fermentability of the basal diet and SC supplementation on DMI has not yet been addressed. Therefore, the objective of a study by Dr W.

Bacterial contamination of foods may lead to reduced shelf life due to outgrowth of spoilage organisms and, in the case of pathogens, to food borne illness upon consumption of contaminated products. To inactivate bacteria that may grow in finished products, many food products undergo heat treatment. Pasteurisation results in inactivation of vegetative cells. However, bacterial spores will survive such treatments, after which they may germinate and grow in finished liquid products.

Choline is a known essential nutrient as it is required for synthesis of essential membrane phospholipids, acts as a precursor for synthesis of acetylcholine, and in particular, has a role in lipid intermediary metabolism. In ruminants, however, almost all dietary choline is degraded by ruminal microbes and requires choline to be supplemented in a rumen-protected form. 

Successful management of an automatic milking system (AMS) requires effective functioning of the milking unit (MU). It is well established that an increased detachment level, i.e. earlier removal of the teat cups at the end of milking, can decrease milking time substantially with minimal to no milk yield loss. However, these studies were all conducted at cluster level, and some studies suggest an increase in residual milk or strip yield at increased cluster detachment levels, which indicates decreased udder emptying.

Trace minerals such as Cu, Zn, and Mn are essential to life, and their deficiencies in livestock result in health deterioration. In an effort to prevent such deficiencies, dairy cows are commonly supplemented with Cu, Zn, and Mn. Various sources of trace minerals are used for this purpose, with inorganic sources (oxides, chlorides, sulphates, and carbonates) being the most commonly supplemented to dairy cows. Alternative sources such as organically complexed trace mineral supplements (chelates) are specifically developed to provide greater nutritional bioavailability.

branched-chain volatile fatty acids, valerate. 

The onset of lactation markedly increases nutrient requirements of dairy cows. The concomitant reduction in feed intake around calving predisposes transition cows to a negative nutrient balance. High-yielding dairy cows may mobilize as much as 1 kg of tissue protein per day from skeletal muscle during the first 7 to 10 days of lactation to meet their amino acid requirements. Additionally, protein mobilization starts before parturition, likely to meet amino acid requirements for growth of the foetus, uterus, and udder tissue.