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Automatic Milking Systems- Land and Pasture Considerations

08 February 2013

Automatic Milking Systems have been explored at Sydney University where Dr Rafiq Islam and Cameron Clark looked into the implications of pasture management and cow walking distances.

Land Areas and Walking Required By Large Ams Herds

Walking distances of greater than 1-km are associated with an increased incidence of undesirably long milking intervals and reduced milk yield in pasture-based automatic milking system (AMS). Therefore, in future the greatest challenge to maintain a large pasture-based herd would be to limit the walking distance in AMS. The aim of this study was to investigate the total land area required and associated walking distance for large AMS herds when incorporating complementary forage rotations (CFR) into the system.

Thirty-six scenarios consisting of 3 AMS herds (400, 600, 800 cows), 2 pasture utilisation (current AMS utilisation of 15.0 t dry matter [DM]/ha, termed as moderate; optimum pasture utilisation of 19.7 t DM/ha, termed as high) and 6 rates of replacement of each of these pastures by grazeable CFR (0, 10, 20, 30, 40, 50%) were investigated.

Results showed that AMS cows required to walk greater than 1-km when the farm area is greater than 86 ha (Fig. 1).

Walking distances (km) required by cows for different farm areas (legends show distances in km)

A 400 cow herd requires 100 ha (13% of paddocks outside 1-km) and 80 ha (all paddocks within 1-km) on moderate and high pasture-based AMS system, respectively (Table 1).

Introduction of pasture (moderate): CFR in AMS at a ratio of 70:30 can feed a 400 cow AMS herd.

Farm Areas and Stocking Rate of Cows Required for Different Herd Sizes Managed in Moderate and High Pasture Utilisation System with Different Rates of Grazeable Complementary Forage Rotation (CFR) in Automatic Milking System

A 600 cow herd requires 150 ha (46% of paddocks outside 1-km) and 120 ha (27% paddocks outside 1-km) on moderate and high pasture-based AMS system, respectively (Table 1; Fig. 1).

An 800 cow herd required 200 ha (60% paddocks outside 1-km) and 160 ha (47% paddocks outside 1-km) on moderate and high pasture-based AMS system, respectively. Although land requirement decreased with the increase of CFR, it cannot feed large herds.

Given the impact of increasing land area past 86 ha on walking distance, cow numbers could be increased by purchasing feed from off the milking platform and/or using the land outside 1-km distance for conserved feed.

However, this warrants further investigations into risk analyses (both management and financial) of different management options including development of an innovative system in order to manage large herds in an AMS farming system.

The Application of Pasture Management Principles in AMS

On dairy farms in Australia with conventional milking systems (CMS), feed and labour contribute the greatest proportion of costs. Grazed pasture as a feed source continues to be pivotal to controlling feed costs on CMS as well-managed grazed pasture remains one of the highest quality and cheapest feed sources on dairy farms.

In this regard, there are established principles for pasture management based around the concepts of leaf stage, pre- and post-grazing pasture mass and post-grazing pasture height. While research on pasture utilisation in AMS is available, there is little information reporting the feasibility of incorporating any of these pasture management principles into AMS farms.

The aim of this study was to determine pre- and post-grazing height for pasture-based AMS with the hypothesis that CMS management principles based on pasture height/mass can be successfully applied to AMS farms.

The results of this study conducted over 2 years indicate that pasture management principles based on pre- and post-graze mass can be successfully applied in AMS farms. Accurate allocation of feed ensured that pre- and post-grazing mass were maintained within the boundaries determined by best practice management (see Figure 1).

Day (solid line) and night (dashed line) pre (filled) and post (open) pasture cover (kg DM/ha) for each month of the trial period. The upper (pre) and lower (post) error bars indicate the average standard error of the difference.

For instance, post-grazing pasture mass was consistently maintained at around 1,500kg DM/ha (equivalent to around 5-6cm height). Also, milk production (?6,500 L milk/cow) and pasture utilisation (?12t DM/ha) were maintained at levels well above Australian industry averages of 5,700L milk/cow and 7-8t DM/ha, respectively.

February 2013

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