Autumn management

The focus in autumn is reaching average pasture cover and cow condition targets ready for spring.

• Focus on leaving consistent post-grazing residuals
• Body condition score the herd for proactive feed management
• Complete an autumn feed budget to identify feed shortages
• Ensure any pasture renewal is a quality job, target autumn pests where possible
• Build APC by increasing rotation length.

Pasture Management (March to May)

Good grazing management through early autumn is maximising the pasture you grow and utilise, balanced with allowing pastures to recover following any dry periods in the summer.

The secret to achieving this good grazing management is leaving consistent post-grazing residuals and graze pastures at the right time (2.5-3 leaves). Grazing ryegrass pastures too early reduces autumn growth and too late reduces quality.

Good management: improved persistence

• Grazing at the 2½ - to 3-leaf stage. During May, the rotation length may be extended beyond this to start building feed for winter.
• Preventing grazing below 7 clicks/1500 kg DM/ha.
• If residuals are less than 7 clicks/1500 kg DM/ha, feed supplement to maintain herd intake and protect pasture. If there is no supplement available then stand cows off pasture once they reach the target residual

Poor management: reduced persistence

• Allocating too much pasture area (fast rotation) immediately after rain
• Frequent intense grazing before plants reach the three leaf stage reduces recovery of tiller numbers during autumn.

Rotation length

Successful autumn grazing involves knowledge of likely winter pasture growth rates for the farm from mid-May to mid-July, relative to the likely feed demand over this period. To plan autumn rotation targets correctly you need to determine if winter feed demand is likely to be greater than or less than winter pasture growth. Using this knowledge as a basis for an end of May target, along with growth rates and leaf stage over autumn will help to set the most appropriate rotation lengths for your farm.

It is important to determine the leaf stage of your own pastures. Leaf appearance rates mainly depend on temperature and water availability with leaves taking longer to appear in colder temperatures or where water is limited.

The following table shows the approximate leaf appearance rates for different regions in autumn; this can be used as a guide to determine rotation length.

Minimum rotation length (e.g. two leaf stage): Time taken for one leaf to fully grow x 2

Maximum rotation length: Time taken for one leaf to grow x3

To determine the leaf stage of your own pasture, collect 10 tillers and compare the leaf stages with the grazing pocket guide pages 10 & 11.

Autumn nitrogen

If your average pasture cover is below target (to meet APC at dryoff and then calving), additional N-fertiliser may help autumn pasture growth rates. Keep N-applications under the190kg/ha per paddock cap, allow enough time between fertiliser application and grazing, and ensure weather or other factors won't limit N-responses.

Feed management and BCS

Whole herd body condition score (BCS) assessment is a powerful tool to assist proactive feed management during autumn and to sort mobs of cows for differential feeding during winter.

To manage calving BCS targets, the herd must be assessed in early March. There are a number of strategies managers can use to get every cow close to her ideal BCS at calving.

Early calving cows

From early March, OAD milking and feeding milker’s supplements are not effective ways to gain BCS in early-calving cows. To hit targets, cows need to be dried-off based on their individual BCS, their approximate calving date, and the amount of supplementary feed available for autumn feeding.

Late-calving cows

For later-calving cows, OAD milking and supplementary feeds can form a part of the strategy for BCS management. But the time taken to gain the necessary BCS must be considered. Particular attention must be paid to R2s and heifers finishing their first lactation.

Autumn feed budget

An autumn feed budget can be used to reflect on the current feed supply and demand situation, and plan ahead to reach cow condition and pasture cover targets.

Autumn feed budget considerations

Feed supply

• Meeting pasture cover targets
• Using N to boost autumn pasture growth.
• Utilising home-grown feed
• Strategically using supplement and grazed crops,
• Off farm grazing

Matching feed demand

• Culling low producing cows
• Demand of returning replacements
• Length of time at off farm grazing
• Drying off
• Feed requirements for BCS targets (and time!)

Autumn pasture renewal

If you are planning to renew poor performing pastures firstly identify the poor performing paddocks for renewal and address the underlining problems behind pasture deterioration. Consider soil fertility and pH, over-grazing, pugging, drainage, soil compaction, weeds and pests.

Right sowing date

• For areas north of Taupo, the recommended renewal date is March 31 and for the lower North Island around March 20.
• If permanent pasture is following crop consider the time for full crop utilisation and the renewal process.

Quality job

• Buy quality seed and select the right pasture species and/or cultivar for your farm
• Sowing a small area well is less risky than sowing a large area poorly.
  • Consolidate your seed bed
  • Take-care sowing clover, clover should be sown at a shallower depth than ryegrass
  • Attention to weed control, contouring and levelling if avoiding cultivation after forage crops.

After sowing and first grazing

New pastures should first be grazed when the plants break off rather than pulled out when plucked by hand. Use the pluck test to test when to graze. The first grazing should be a quick nip off with (top 2-3cm) with young stock or 2-3 hours grazing with cows.

• New grass often becomes nitrogen deficient 2-3months after sowing, particularity after a wet spell. Look out for yellow leaf tips, the most obvious symptom of this occurring. Small applications of nitrogen (20-30 kg N/ha) from 6-8 weeks after sowing will increase seedling size before summer
• Before 1st grazing it may pay to test a sample for nitrate toxicity – Nitrate poisoning is not uncommon when grazing resown pastures especially annuals.
• Weed control - spray new pastures. Monitor your new pasture for weeds, seedlings weeds can be sprayed before or after 1st grazing. Spraying should be delayed if there is more than 50% bare ground. Waiting for all clover plants to be big enough to spray means that weeds are often to advance to control.

For more information on identification and control check out Pests, Weeds and Diseases or AgPest

Feed management tools

Completing a simple feed budget will identify any shortage in home-grown feed and therefore determine if supplementary feed is needed.