Despite the decent summer and back end, a number of farmers – particularly in the North of the country – are concerned that they may not have sufficient forage to get them through the winter ahead.
For those farmers, who have had cattle indoors for longer than normal or than had been budgeted for, it would be wise to check out feed stocks against requirements now so as to avoid panic about feed supply next spring.
To calculate their requirements producers should get pen and paper, make two columns with all feed supplies on one side and requirements on the other. On the supply side, list the tonnes of conventional silage, got by measuring the cubic capacity of the pit in cubic metres or cubic feet (1 tonne = 1.3 cu metres or 50cu ft, approximately); the number of bales of silage , hay and feeding straw; other forages such as roots and green crops. Baled silage can vary widely in dry matter (DM).
If baled directly, or after some time on the ground in wet weather where no wilting occurred, the dry matter may be the same as conventional silage, for example, 20-22 per cent DM. If there was a successful wilt of one to two days in good weather, the dry matter could be 25-35 per cent.
On average, baled silage turns out to be about 28-32 per cent DM. A tonne of pit silage of 20 per cent DM contains 200kg DM (1000×20 per cent=200), while a 650kg bale of silage at 30 per cent DM contains almost the same dry matter (650×30 per cent=195kg).
Therefore, you can almost equate a bale of wilted silage with a tonne of pit silage in terms of DM. However, the feeding value could be quite different, depending on the digestibility of the respective silages.
On the demand side, list the number of stock in each category and their requirements per month, multiplied by the number of months of indoor feeding. Suckler cows will eat 1.25 tonnes of silage per month, store bullocks (500 kilos) 1.5 tonnes and weanlings (300 kilos) 0.8 tonnes per month.
Following the completion of these calculations if a shortage is anticipated, then producers need to look at the options. Obviously, these involve lowering the demand or increasing the supply. Lowering the demand could be done by reducing the feed allowance to (some) stock or by the earlier sale of stock. Neither of these may be sensible options.
Dry suckler cows in very good condition can be restricted but should not be allowed go below body condition score 2.5 at calving in spring. Weanlings and store cattle going to grass in spring have a target daily gain of about 0.5kg and should be fed silage to appetite plus appropriate supplementation depending on silage quality.
To increase the supply there is the choice of buying forage and/or buying additional concentrates. How the forage and concentrates are rationed between the various stock depends on their stage in the production cycle, their overall feed requirements and convenience factors. As a general guide, target the large roughage consumers for restricted or minimum roughage allowance, rather than the weanlings that are smaller users of roughage.
In this regard, finishing cattle can be put on an all-concentrate diet and sucker cows can be put on a restricted roughage diet of silage or straw supplemented with concentrates. All stock need a minimum daily allowance of roughage to maintain satisfactory rumen function.