The Research Column

Rumen function in the dairy cow is negatively affected by heat stress: Changes such as decreased rumination time and lower pH have been reported, as well as lower rumen motility. Altogether, these induce changes in rumen fermentation and gas outcomes, including VFA profiles, and consequently in enteric methane (CH₄).

Replacement heifers are important in the dairy herd because they are the next generation lactating cows, but the costs to raise them is a major expense. This implies that dairy farms must find ways to balance between supporting satisfactory growth, while also minimizing the costs associated with raising heifers.

Although on-farm limitation of heat stress through environmental modifications, such as using shade, fans, and mechanical cooling systems, are routinely implemented and have helped to reduce heat stress, the ability of dairy cows to dissipate body heat under chronic heat stress is minimal. Therefore, other interventions are critical under such conditions.

Trace minerals such as Cu, Mn, and Zn are essential for tissue integrity, antioxidant defense, and immune function, and inadequate intake of minerals might predispose cows to health disorders, especially during the transition period when oxidative stress and inflammation originating from calving increase susceptibility to post-calving diseases.

Contrary to conventional dairy cattle farming which focus on increased farm profitability due to increased cow productivity, low-input systems aim for efficient pasture-based milk production by reducing production costs. Low-input dairy cattle systems are also highly appreciated by consumers, because of welfare perceptions.

The microbial quality of milk is improved via processing steps such as pasteurization, which reduces the overall microbial population in milk and which is particularly effective against gram-negative, heat-sensitive bacteria.

In dairy cows, the period immediately preceding calving is responsible for shifts in hormonal and nutritional status characterised by mobilization of body fat, proteins, and bone minerals to support the onset of lactation. After calf birth, the dairy cow often experiences negative energy balance despite a gradual increase in dry matter intake (DMI).

Increasing ruminal propionate relative to acetate production and alleviating excessive proteolysis are viable strategies for improving efficiency and can be achieved through supplementation of the ionophore monensin.

To enhance sustainable productivity and mitigate methane (CH4) emissions from ruminants, the adoption of herbs in dairy diets has gained increasing attention. Among these, chicory is considered one of the most promising forage options for grazing livestock due to its nutritional and agronomic benefits.

Taking the calf away from the mother is common practice in global dairy production systems. This practice is to prevent disease in new-born calves due to pathogens shed by cows, for better control of colostrum management and milk intake, and to maximize milk yield, improve efficiency of milking, prevent intra-udder infections in cows, and minimize separation stress after the bond between cow and calf has been formed.