Mary Kinston: Whisper it, but we could do with a dash of rain

Mary Kinston

Breeding and grassland management have been the main topics of conversation at my discussion group in recent weeks.

In general, it's been a decent breeding season, with strong heats. Many herds have achieved submission rates at 21 days of mating or greater than 85pc.

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Cows are in great condition, milking well and breeding well, which is no surprise given the extremely kind winter and spring. All in all, 2019 is set up to be a bumper year.

However, there are concerns about the lack of rain and increasingly dry conditions.

While I feel loathe to mention the weather in what has been such a great year, after 2018 it's hard to ignore farmers' potential fears and concerns.

Measuring grass to track changes in growth rate on a weekly basis becomes important in this situation.

Once grass growth falls substantially and is notably less than per hectare demand - e.g. 15-20kgDM/ha less - one must consider options to manage the dry conditions.

However, I must stress the importance of being farm specific with this and not following the crowd.

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Soil moisture deficits can vary considerably between farms subject to differences in weather, shelter, height above sea level, aspect, soil type, nutrient status and even grass species and variety.

Drought management actions conflict with actions to maintain pasture quality. So deciding whether action is needed and the timing of implementation will impact the herd's milk production and profitability.

Another key point is to consider is the accuracy in grass measurement.

In drying conditions, the under-estimation of grass in a paddock can become significant.

For every 1pc increase in herbage dry matter, the average cover in the paddock will rise by 200kgDM/ha.

While hard to determine visually, the rise in pre-grazing covers becomes obvious when rotation length extends. There is a slight reduction in the area grazed per day or grazing residuals are rising with more grass left in the paddock.

Its very easy to reduce growth rates if we simply underestimate grass cover from one week to another, so do take this into consideration.

Touch the grass and determine whether it feels lush or dry.

If it's dry and more rigid than normal consider closer to 20pc DM, as drying conditions will increase grass DM from week to week.

If daily grass growth, the pasture wedge and average pasture cover indicate that the farm is starting to become moisture-stressed, the following actions should be considered;

Extend Rotation Length to 25-30 days

The first step is to lengthen the rotation length from around 20 days (1/20th of the farm) to 25 days and if growth continues to fall to less than 30kgDM/ha/day, extend to 30 days (1/30th).

While some paddocks may start to become stemmy with unsightly seed heads, resist the urge in this rotation to top or pre-mow prior to grazing as this will hinder grass growth and recovery until adequate rain has been received.

Supplement with high energy feed and 16pc crude protein

In drought conditions, cows need high or increased levels of supplementation as grass growth and quality declines.

However, to get high responses to supplement it must be balanced with achieving good grazing residuals.

It's imperative that the available pasture is eaten and not wasted. Leaving poor grazing residuals (>4cm) will only decline pasture quality further. Meal should be fed up to 7kg before forage is introduced. The use of winter feed reserves is the last resort.

Continue to apply fertiliser until the drought conditions are obvious

Applying nitrogen (CAN rather than urea) before the soil moisture becomes limiting helps the perennial ryegrass plant convert from producing seed heads to high quality leaf by promoting vegetative tiller growth.

Once the growth declines below 15kgDM/ha and grass becomes brown and crunchy, stop.

Hopefully this slight dry concern will dissipate before it becomes a really significant issue.

Indo Farming


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