The Research Column

In the ultra-high temperature (UHT) process, milk is subjected to high temperatures, above 135 oC for a few seconds, resulting in a product with a shelf-life of several months when stored at ambient temperature. However, chemical and physical changes in the milk can lead to off-flavours, browning, fat separation, sediment formation or gelation during  storage. Important associated factors are processing parameters, storage conditions (time and temperature) and type of packaging.

branched-chain volatile fatty acids, valerate. 

Time of dry-off, calving and the start of a new lactation are critical transition events for a dairy cow. Large changes in both physiology and management increase the risk for disease and culling. The cow faces these transition events every year, as a one-year calving interval is usually aimed for. A one-year calving interval is usually associated with a good average 305-day yield and better economic results compared with longer calving intervals.

Lactation yield estimates standardized to common lactation lengths of 270 or 305 days are commonly used in management decisions and genetic evaluations. The use of such measurements to quantify the merit of individual cows fails to penalize cows that do not reach the standardized lactation length, or vice versa to reward cows that lactate for more than the standardized lactation length. The objective of a study by Dr M.

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.

Mycotoxins are a diverse group of secondary metabolites produced by many fungi in the genera Aspergillus, Fusarium and Penicillium. They may cause toxic responses when ingested by humans and farm animals. Among the mycotoxins, those produced by Fusarium spp.

Soils underpin the requirements for health and longevity of mankind. They are critical, providing the basis of food production, a store and filter for water resources, the largest organic carbon store and a platform for development. Pressures on the soil resource grow as food demands rise and land degradation increases.

Numerous studies have shown the negative effects of heat stress during the dry period on dairy cow performance during the subsequent lactation. Exposure of cows to heat stress during the dry period is associated with compromised mammary cell formation and decreases in milk yield in the subsequent lactation. Moreover, a greater incidence of postpartum disorders and lower reproductive performance are associated with exposure of cows to heat stress during the dry period. Dry period heat stress also decreases dry matter intake and body weight, gestation length, and calf weight.

Nitrous oxide (N2O) is a long-lived stratospheric ozone-depleting substance and greenhouse gas with an atmospheric lifetime of about 110-120 years. The concentration of atmospheric N2O has increased by more than 20% from 270 parts per billion (ppb) in 1750 to 331 ppb in 2018, with the fastest growth being in the last fifty years. Two key biochemical processes—nitrification and de-nitrification—control N2O production in both land and water ecosystems.

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.