Achieving High Dry-Matter Intake From Pasture With Grazing Dairy Cows

Abstract

Abstract. Due to economic, environmental and animal-welfare constraints, it is envisaged that in the future a larger proportion of the milk produced in temperate regions will be produced from grazed pasture. However, with the selection of modern higher-production dairy cows, increased emphasis on product quality and issues associated with nitrogen leaching, soil compaction, greenhouse-gas emissions and animal welfare, pasture-based systems will also require higher per-animal productivity in the future. This will necessitate the development of grazing systems designed to maximize daily herbage intake per cow, while at the same time maintain a high-quality pasture over the entire grazing season. Daily grass DM intake will be maximized by adhering to important sward characteristics such as maintaining a high proportion of green leaf within the grazing horizon while allocating an adequate daily herbage allowance. Increasing the green-leaf proportion at the base of the sward through appropriate grazing management in early spring may play an important role in increasing herbage intake and making grazing management easier. This requires knowledge of the carryover effect of early-season grazing management on midseason pasture quality and the implication for milk output per hectare. The present plant selection and evaluation systems target improved grass DM yields rather than parameters that influence animal performance. There is a clear requirement for an increased selection emphasis on characteristics that influence animal performance, i.e., herbage intake. This can be best achieved by adopting an interdisciplinary approach with plant physiologists, nutritionists, breeders and evaluators sharing knowledge and resources. Likewise, in the future the cow genotype must be compatible with the system of milk production, and prediction of the phenotypic performance of dairy cattle must be based on knowledge of the cows' genotype as well as the environment in which they are managed. The development of reliable, easy to use decision support tools that facilitate increased reliance on grazed grass, to be used by farmers and extension services, will contribute to optimize animal performance from grazed pasture.

Meta-analysis of the impact of stocking rate on the productivity of pasture-based milk production systems

“…The actual reduction in milk production observed (1.1 kg milk/2.5 UFL 5 0.44 kg) is similar to that associated with a 1-kg reduction in daily herbage allowance (Peyraud et al, 2001). While it is widely acknowledged that milk production from pasture is dependent on numerous environmental, plant, animal and management factors controlling herbage intake and rumen digestion (Dillon, 2006), the results of this analysis illustrate that as SR increases by one cow/ha, the net energetic consequences are akin to a reduction of 1 kg in daily herbage allowance per cow. Holmes et al (2002) suggested that cows per ha is increasingly misleading as a measure of the balance between feed demand and supply, although cows per ha is still widely used.…”

Differential response to stocking rates and feeding by two genotypes of Holstein-Friesian cows in a pasture-based automatic milking system

“…However, the biological efficiency of supplementation can vary widely as it can be affected by several co-varying factors, including the level of pasture allowance and pasture intake, and the type and amount of supplementation (Dillon, 2006). Grazing cows fed starch-or silage-based supplements are known to achieve satiety sooner, thus reaching faster cessation of grazing with concurrent decreases in pasture intake (Hills et al, 2015).…”

“…Grazing cows fed starch-or silage-based supplements are known to achieve satiety sooner, thus reaching faster cessation of grazing with concurrent decreases in pasture intake (Hills et al, 2015). Consequently, the resulting substitution rate, or decrease of pasture intake per kilogram of supplement, could reduce the marginal milk response per kilogram of supplementation (Bargo et al, 2002;Dillon, 2006). As a general rule, greater milk response to supplementation is obtained in high stocking rate (HSR) systems because conditions that are necessary to minimize pasture substitution (i.e.…”

Effects of stocking rate, supplementation, genotype and their interactions on grazing dairy systems: a review

“…There has been renewed international interest in grazing production systems (Macdonald et al 2008a) as a result of (i) reductions in milk prices in many countries, (ii) increments in production costs (Dillon et al 2005) and (iii) perceived environmental and animal welfare concerns associated with intensive dairying (Dillon 2006). This interest has triggered further studies on stocking rate (SR)*a topic extensively studied in countries with pasturebased dairy systems since the 1960s.…”

“…Herbage intake at grazing Intake of herbage has been identified as the main factor limiting milk yield of grazing cows (Leaver 1985;Dillon 2006). HI is affected by environmental factors such as rainfall and temperature, pasture characteristics such as herbage mass and structure, sward species, herbage quality Dillon 2006), and cow characteristics including genetic potential for milk yield (Horan et al 2006), stage of lactation (Stockdale et al 1987), LW and parity (Peyraud et al 1996).…”