PHOTO: THE NATIONAL DAIRY COUNCIL
PHOTO: PROFESSOR MARCIA ENDRES
FEED ▶▶▶
the pasture. Prof Endres says the technology can determine a baseline of normal behaviour for individual cows and for the herd. While individual cow alerts could point to health issues or estrus, herd-level behaviour information “could possibly help us decide if cows should be moved to a new paddock,” says Prof Endres, “every 12 hours or every 24 hours.” Some dairy farmers are also now using virtual fence systems, similar to technologies for pet dogs, to manage movement of pastured cows. The cows wear GPS-enabled collars that keep them in the chosen area or move them along with beeps or if needed, a mild electrical pulse. One called Boviguard was de- veloped in the United Kingdom, and another has been pat- ented by Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia. Yet another virtual fence system is being developed at WUR.
High stocking densities Klootwijk and her colleagues note that dairy farmers have been decreasing the use of grazing in several European coun- tries because of larger herd size, increased milk yield per cow and more robotic milkers. (In the Netherlands, the decreasing trend of grazing is actually reversing nowadays due to soci- etal pressure.) Many farmers with these types of farms, who usually also have high stocking densities on the available grazing area, may not want to try grazing as it might reduce milk yield or have higher labour costs, and they may be un- certain about the practice being worthwhile. However, in her PhD thesis, Klootwijk found that compart- mented continuous grazing (CCG) and strip grazing (SG) can support fresh grass intake of high-yielding dairy cows at high stocking densities on the available grazing area (7.5 dairy cows/ha) without compromising milk production. SG is de- signed to maximise grass yield but requires a high level of management skills and extra labour to move fences daily; CCG features fixed fencing and less management skill but provides lower grass yield.
Environmental impact We have already noted that pasture use is environmentally sound because it reduces use of crops and the transport of crops/feed over short or long distances to the farm. Adam Shorten is one dairy farmer with long experience managing pasture use while reducing the environmental impact on his Murragh Farm in Ireland. Shorten was a finalist in the 2019 Na- tional Dairy Council & Kerrygold Quality Milk Awards; its entry criteria was recently expanded to include sustainability aspects. Shorten measures his grass every week and aims for over 1,400kg DM/ha, allowing his cows to graze paddocks to 4cm. He does soil testing and adds appropriate amendments to his pasture as well. Over time, Shorten has extended his grass growth season by using on/off grazing, and among his future plans are adapting clover to pasture swards and obtaining cows bred to be more efficient in grass-based feeding systems.
To help farmers maximise the use of grazed grass while avoiding pasture damage, the Agri-Food and Biosciences Institute in Northern Ireland has issued guidelines. These in- clude walking the grazing platform at least once a week, batching cows, pre-mowing and, during periods of wet weather, adopting a flexible approach that “may involve on/ off grazing, allowing cows to graze for a few hours after milking and fed silage when housed”.
Looking forward It’s clear that while the learning curve for pasture use may be a little steep initially, success can be achieved. Cows must not be permitted to eat spring grass until it’s past the third- leaf stage, and farmers must calculate fresh grass allowance accurately and move their cows appropriately, using technol- ogy where possible to save labour. However, while Klootwijk notes that successful use of pas- ture is possible even on farms with high stocking density on the grazing area – and can be a valuable first step in reduc- ing supplementary feeding and enabling cows to express natural behaviour – she wonders if it is the route to the future. On that note, she believes that farmers may be able to in- crease their use of pasture through reducing feed supple- mentation, making their cows more motivated to graze. “A lower stocking density relies less heavily on feed supplemen- tation,” she adds, “which can reduce feed–food competition, and may also provide room for biodiversity. A next step in the search towards sustainable grazing is to explore the val- ue of different mixtures of grasses, legumes and herbs to in- crease the resilience of the grazing system.”
▶DAIRY GLOBAL | Volume 7, No. 3, 2020
Professor Marcia Endres adds that while only 5–8% of lactating dairy cattle across the US are on pasture, this may in- crease due to in- creased consum- er interest in “grass-fed” milk, which pays a premium.
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