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Autumn pasture management in dairy farming involves focusing on average pasture cover and cow condition to prepare for spring. The page details guidelines for achieving this through consistent post-grazing residuals, body condition scoring, autumn feed budgeting, pasture renewal, and rotation length management. Information on managing pasture growth rates, leaf appearance rates in different regions, and the use of Nitrogen fertiliser is included. Strategies for whole herd body condition, autumn feed budget considerations, pasture renewal, and autumn pest control are also addressed, along with some tools for feed management. Following these practices will lead to improved persistence and quality in your pastures.
The focus in autumn is reaching average pasture cover and cow condition targets ready for spring.
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.
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 guideline to regional leaf appearance rates based on average monthly temperatures
|Region||North land||Nth Waikato||Sth Waikato||BOP||Taranaki||Lower NI||Top of South/ WC||Canterbury / N. Otago||Southland / S. Otago|
|Average Autumn temp||14-20°C||12-20°C||10-18°C||11-20°C||10-18°C||10-18°C||10-18°C||6-16°C||6-15°C|
|Time taken for one leaf to fully grow||8-12 days||8-14 Days||10-17 days||8-16 days||10-17 days||10-17 days||10-17 days||11-28 days||12-28 days|
Adapted from Julia Lee et al., DNZ Technical Series Issue 3. Assumes that available soil moisture is at minimum 40%, if less than 40% time taken for a leaf to fully grow will increase dramatically. This is a guide actual rate will vary with temperature and water.
If farm cover is below where is should be (in order to meet target cover at calving) N fertiliser can be a great ‘circuit breaker’ to get growth back on track. Use a large part of the farm for best effect.
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.
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.
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.
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
Matching feed demand
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.
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.
|Autumn Pest||Type of damage||Autumn management considerations|
|Adult black beetle||Cause of autumn damage, yellowing tillers that pull easily from the pasture||Summer grasses are a good host. Eliminating summer grasses where possible through good renewal practice. When consider break crops and when renewing use the right endophyte and treated seed|
|Brassica aphid, cabbage aphid, grey cabbage aphid||Stunt plant growth Transmit plant viruses.||Autumn sprays as directed by your consultant or industry representative. Removal of weeds that can act as host|
|Clover root weevil||Adults notching in clover leaves, larvae feed on roots/ root nodules. Can result in total clover loss||Pasture establishment application of insecticide can be used close to seedling emergence to control adults, provides a window in which clover plants may establish before re-invasion .|
|Grass grub, brown beetle larvae||Feed on roots. Densities greater than an average of 8 larvae per spade square (200/m2) will cause damage.||Digging - from mid-February to measure damage AgPest. Early warning strips in Autumn. Chemical control after sampling based on density|
|Lucerne Weevil||Seedling stands can be attacked in autumn. Adults attack foliage. Larval feeding on root||Insecticidal control against adult weevils returning to Lucerne at the end of autumn. Insecticidal control should only be used when damage is severe.|
|Porina Caterpillar||Caterpillars and the damage they cause are most noticeable from April until September. At high densities plants are destroyed allowing inferior plant species to establish||No of different species require different assessment - Agpest for appropriate autumn management and control.|
|Tasmanian Grass Grub||Autumn sown brassica crops and legume seedlings can be severely damaged as larvae sever plant stems and the plants will die.||Larvae in the soil in autumn. When larvae are present at damaging levels insecticide may be the only recourse to limit damage and save pasture. Maintaining good pasture cover during January/February reduces the availability of egg laying sites.|
Completing a simple feed budget will identify any shortage in home-grown feed and therefore determine if supplementary feed is needed.