The Research Column

Determining the optimal insemination time for individual cows is not always easy, as amongst others, pregnancy also has an effect on absolute milk yield; the latter which has been reported in several studies.

Some consumers prefer pasture-derived dairy products, as they perceive outdoor pasture-based feeding systems as a more natural environment for animals. Despite this, the number of grazing animals globally has declined as a result of the higher milk yields achieved by indoor TMR feeding systems, in addition to the changing climatic conditions to control the milking environment.

In the majority of calf rearing systems, dairy calves are raised in individual hutches for biocontainment purposes and to facilitate monitoring and handling of calves. However, individual hutches restrict calves’ activity and social interactions. Some studies showed that group housing (GH) may be beneficial to calf welfare and is associated with social benefits. However, the adoption of GH on dairies is hindered by several concerns, with the primary concern being the potential for increased transmission of diseases due to heightened calf-to-calf contact.

The profitability of seasonal, pasture-based dairy systems is substantially reduced by poor reproductive performance. Dairy producers desire a timely and condensed calving pattern as a strategy to align the feed demands of the herd to the seasonal feed supply from pasture grazed. Holstein-Friesian and Jersey cattle have gestation lengths around 280 days; therefore, to maintain an annual calving pattern, each cow must resume normal oestrous cycles and initiate a pregnancy within 85 days after calving.

The dairy cow experiences impaired health, productivity, fertility, and overall welfare when outside her thermo-neutral zone. The thermo-neutral zone is defined as the range of temperatures within which no additional energy is spent to heat or cool the body and typically falls between 5°C and 25°C for dairy cows.

Persistency of lactation measures the ability of a cow to maintain daily production following peak production. A cow with more persistency of production usually have a more horizontal lactation curve compared with a cow with less persistency of production.

The importance of obtaining greenhouse gas (GHG) and corresponding resource use data on dairy farms cannot be emphasised enough, as baseline data is required to evaluate where to put emphasis in mitigation or change. The publication from South-Western Sweden cited provides such an opportunity. The authors collected data and use Life Cycle Assessment (LCA) methodology in analysis.

Feed efficiency in dairy cattle is important as feed represents over 50% of the total production costs, but there are also several other benefits to improve feed efficiency, including increased farm profitability and reducing the environmental 

For a food to be considered a good source of calcium (Ca), it must have a high Ca concentration and the Ca must be highly bioavailable. Dairy products have traditionally been considered excellent sources of Ca due to both a high Ca density and bioavailability. For example, a glass of 240 mL milk is estimated to contain 300 mg Ca, providing about 96 mg absorbable Ca and a bioavailability of 30 %, which is considered to be high.

Enteric methane production needs to be reduced in livestock, also in dairy cows. Methanogenesis by methanogens in the rumen is responsible as their fermentation results in hydrogen accumulation which is usually picked up into the CH₄ molecule as one of the end products.