Dairy notes September 2006
Grazing Management
Good quality September grazing is capable of producing 15 litres of milk without feeding concetrate. Swards should be grazed off at a cover of 3,300-3,500 KG DM/ha – a sward height of 16-18 cm (6-7 inches). Silage aftermaths can be successfully grazed at a slightly heavier cover of 3,800-4,000 KGs DM/ha.
Growth conditions have improved following recent rainfall. Grass covers should be carefully monitored to ensure they don’t become too heavy. If covers are reaching 4,300 – 4,500 KGs DM/ha., graze the swards lightly with the milking herd and use dry stock as a follower group to clean off the remainder.
Planning Winter Feeding
The feeding value of this year’s first cut silage may not be as poor as cutting date alone would have suggested. Cold weather in spring delayed crop maturity and dry-matters are likely to be higher than normal (30 percent +). Both of these factors will increase silage intakes. Last year protein levels in silage were generally low but early indications are that they are at normal levels (13-15 percent) this season.
With milk price well below last years level, it will be critical to ensure concentrates are not fed above economic levels during this winter. Now is the time to have a silage analysis carried out. This will provide an accurate assessment of silage feed value and intake potential, allowing you to select:
- The correct concentrate level to maximise milk from silage – for example, does a cow producing 35 litres of milk require 9 or 11 KGs concentrate?
- The correct concentrate crude protein percent to balance demand – a cow in early lactation requires an overall crude protein in the diet of 17-18 percent in the dry matter.
- The correct concentrate ingredients to maximise silage intake – high quality silage needs to be balanced with cereals, soya and by pass protein sources.
Condition score late lactation cows
Cows should be fed a restricted energy diet during the first week of the dry period to ensure that they are fully dried off. In late pregnancy, the energy demands of the growing calf increase, but in the last two weeks before calving, cow appetite decreases due to the increasing size of the unborn calf. This means that for at least three weeks of the dry period, there is little opportunity to increase cow body condition score. If an improvement in condition score before calving is necessary, dietary changes should be made well before drying off. Ideally the cow should reach condition score 3.0 by drying off, and this condition score should be maintained during the dry period.
Cows calved before December 2005 are now over 250 days into lactation and will probably be drying off from mid-October. To have these cows calving down at condition score 3 it is important to assess their body condition now! These cows should be around body condition score 2.5 at present. If you have cows that have not yet reached this condition and are in late lactation you will need to take action.
Options available include:
- Feeding extra concentrates in late lactation - one unit of body condition score is equivalent to about 60 KG of liveweight and will take two months at a liveweight gain of 1.0 KG per day. For each 0.5 KG of liveweight gain, the extra daily requirement of a good quality concentrate in late lactation is approximately 2.0-2.5 KG. This should ideally be relatively low in crude prtein (16 percent or less fresh weight).
- Drying cows off earlier – particularly relevant for first lactation cows. Projected calving dates should be estimated from the herd records to calculate drying off dates.
- Once daily milking of individual low SCC animals – careful monitoring of SCC results is still necessary.