The Research Column

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. 

Zinc (Zn) is an essential trace mineral and plays an important role in DNA and RNA synthesis and replication and in cell proliferation. Zinc supplementation has been shown to increase milk yield, live weight and growth rate, and enhanced disease resistance. With reference to the latter, it has been suggested that Zn deficiency could result in increased somatic cell count (SCC) and ultimately increase mastitis in dairy cows. 

The health, well-being and reproductive status of dairy cows, apart from profitability in production, should be the most important considerations in animal breeding. Normally though, genetic evaluation focuses mostly on the genotypic background which influences economically important traits such as milk yield and composition. However, in many countries selection for enhanced milk performance has caused a decline in cow reproduction and consequently, this has led to increased interest associated with non-production traits, including reproductive efficiency, longevity and health.

The crossing of parents of unrelated strains, or breeds, often results in offspring that are more robust, with better health, growth, fertility, and production. In dairy cattle, crossbreeding has also been shown to improve functional traits such as fertility, health, calving ability, and survival. Despite the compelling evidence of the benefits of crossbreeding, the majority of dairy farmers still prefer traditional pure breeding, and crossbreeding in dairy cattle is far from common.

Worldwide whole milk powder (WMP) is a dairy product which overcomes the problem of seasonality of raw milk. Additionally, it serves as a product with high nutritional value to remote areas. It has a long shelf life which depends on the conditions of storage and transportation, recommended to be in a range from 0 to 10°C. At higher temperatures, the quality of WMP deteriorates because of an increase in the degradation of fat and protein fractions. A range of low negative temperatures for storage have not been systematically investigated.

Improved animal health and resilience are important breeding objectives for the dairy cow. Many diseases affecting the cow occur in the first 30 days after calving. Some of these diseases are associated with metabolic disorders such as ketosis and milk fever, which can have deleterious effects on animal health and welfare and farm profitability. Although heritability estimates of metabolic disorders are generally low, sufficient genetic variation exists suggesting that improvement in metabolic health through selection should be possible.

Dairy cows often experience negative energy balance in early lactation because the energy intake is insufficient to meet the sudden increase in demand for milk production. Therefore, high-starch diets are usually fed to early-lactation dairy cows to reduce the energy deficit. However, high-starch diets during the first several weeks after calving may decrease rumen pH and further increases the risk of sub-acute ruminal acidosis (SARA).

Infectious diseases, such as metritis and mastitis, have  serious economic consequences due to the use of antibiotic treatment, the withdrawal period thereafter, delayed onset of cyclicity after calving, extended intervals between calving, and poor fertility . Most high-yielding dairy cows struggling with such diseases also have metabolic disorders, and some results have shown a connection between immunological defense and metabolic regulatory mechanisms.

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.

The nutritional and pharmacological advantages of chromium (Cr) for animals and humans have been well established. Trivalent Cr is a component of chromodulin which is involved with insulin regulation, and thereby associated with the metabolism of carbohydrates, protein and lipids. The signs of Cr deficiency include impaired nutrient metabolism, lower sensitivity of the peripheral tissues to insulin, compromised immunity and decreased weight gain and health status, specifically under stressful conditions.