Some challenges and opportunities for grazing dairy cows on temperate pastures

Abstract

Grazing plays an important role in milk production in most regions of the world. In this review, some challenges to the grazing cow are discussed together with opportunities for future improvement. We focus on daily feed intake, efficiency of pasture utilization, output of milk per head, environmental impact of grazing and the nutritional quality to humans of milk produced from dairy cows in contrasting production systems. Challenges are discussed in the context of a trend towards increased size of individual herds and include limited and variable levels of daily herbage consumption, lower levels of milk output per cow, excessive excretion of nitrogenous compounds and requirements for minimal periods of grazing regardless of production system. A major challenge is to engage more farmers in making appropriate adjustments to their grazing management. In relation to product quality, the main challenge is to demonstrate enhanced nutritional/processing benefits of milk from grazed cows. Opportunities include more accurate diet formulations, supplementation of grazed pasture to match macro- and micronutrient supply with animal requirement and plant breeding. The application of robotics and artificial intelligence to pasture management will assist in matching daily supply to animal requirement. Wider consumer recognition of the perceived enhanced nutritional value of milk from grazed cows, together with greater appreciation of the animal health, welfare and behavioural benefits of grazing should contribute to the future sustainability of demand for milk from dairy cows on pasture.

Keywords: grazed pasture; grazing management; herbage intake; milk production; milk quality; nitrogen use efficiency.

Figure 1

Relationships between herbage allowance, DM intake and efficiency of utilization of pasture (Derived from Baudracco et al., 2010)

Figure 2

Effect of annual stocking rate on efficiency of metabolisable energy (ME) utilization (Macdonald et al., 2001)

Figure 3

Relationship between pre‐grazing herbage mass per ha and post‐grazing herbage mass, herbage DM intake and efficiency of pasture utilization (Derived from Baudracco et al., 2010)

Figure 4

Relationships between daily herbage DM offered, herbage DM intake and milk output (Derived from Baudracco et al., 2010)