DairyNZ developer Sean McCarthy provides insights and points to new resources that will help you make the best decisions over the next few months to ensure feed supply is managed in an effective way.
Ensuring feed supply matches demand, for many, will mean continuing to meet pre-grazing leaf stage and post-grazing residual targets to encourage as much pasture growth as possible. It may also include the use of summer crops, nitrogen (N) fertiliser and supplements where it makes economic sense.
Assuming sensible culling and dry off decisions are made to manage feed demand, the focus shifts to supplying high quality, low cost feed.
Before culling and dry off decisions can be made, it is important to have the right information. Knowing the average pasture cover and feed on-hand will enable you to determine if a lift in farm cover is required and whether December is a good time to apply N fertiliser to encourage greater growth rates in early summer. N boosted pasture is a valuable feed source, and even if ensiling is required, it will cost less than many supplements (for an evaluation framework, see the article Supplements, surpluses and savings, pg 12, Inside Dairy October 2015).
Slowly grazing round
A dry summer will slow pasture growth, so slowing down the round in early December by increasing the number of days in the rotation will help achieve maximum growth during summer and help ensure there is adequate feed ahead of your herd for grazing. It will also allow for grazing of pastures closer to the target three-leaf stage, therefore capturing the 40-50 percent of the high quality leaf growth from the second to third leaf (see Perennial ryegrass grazing management booklet at dairynz.co.nz/ grazing-management).
Target residuals for high quality pasture
The way to increase feed is by a slower rotation, not higher residuals. There is a misconception that leaving higher residuals in December will increase feed availability in summer and help capture moisture. Leaves have a limited lifespan so higher residuals will in fact reduce pasture growth and any remaining high quality feed will decay and not be available later in the summer. Therefore, leaving high residuals in December won’t help fill a feed deficit later on; it will simply result in wasted pasture now and reduced pasture growth and quality in the months ahead.
Residuals of 1500-1600kg DM/ha will ensure the plant maintains its energy reserves and will provide some shading of the soil surface.
Feeding summer crops
While the area in crop has by now been determined, it is important to measure and monitor yields so this feed is allocated accurately. Information on managing and feeding individual crops can be found at dairynz.co.nz/crops.
Ask why before you buy
Decision rules around feeding supplements need to be made alongside knowledge of overall expected feed supply and demand (see article on reviewing herd numbers on pg 10).
DairyNZ’s new “Summer Feeding Check” worksheet will take you through the steps to work out when you will get a good financial return from using supplements.
The “Weekly feed management check” template included will help you monitor grazing indicators (pre-grazing yield, rotation length, average farm cover, post-grazing residuals) alongside supplement use to determine whether or not money will be made from feeding supplement.
It also provides a checklist of questions that need to be considered before supplement is purchased.
The worksheet can be downloaded from dairynz.co.nz/ publications/feed.
Supplement use after culling decisions
DairyNZ’s online Supplement Price Calculator will help you determine how much you can pay for supplementary feed during a shortage. It provides a more detailed output with regards to different feed types, amounts and time of the year.
It must be noted that the milk response in these resources is determined based on energy being the limiting factor to milk production. While this is typically the case when cows are eating high quality pasture, in summer/early autumn the availability and quality of the pasture declines and the use of low protein supplements (e.g. maize silage, fodder beet) increases. Therefore in some instances protein may be limiting milk production.
However, protein supplements are usually expensive and even with a milk response, the extra milk revenue does not typically outweigh the cost of feeding a protein supplement (See article Should I supplement with protein in summer? pg 26 in Inside Dairy February 2015).
Another factor to consider if using large amounts of supplements in summer is to ensure cows have adequate effective fibre. For example, although PKE is high in neutral detergent fibre (NDF), it contains no effective fibre. From a rumen health perspective, a forage source (pasture, straw, hay) may need to be included in the diet if PKE is being fed. For more information see DairyNZ’s FeedRight booklet at dairynz.co.nz/publications/feed.
This article was originally published in Inside Dairy December 2015