WITH increasing concentrate prices and winter milk bonuses coming to an end, there has never been a more important time to monitor winter feeding.
Dr Jane Sayers, CAFRE Dairying Adviser in County Tyrone, says that “profitable winter milk production is highly dependent on meeting the nutritional requirements of the dairy herd and selecting a balanced ration will pay dividends through the production of high quality milk and good reproductive performance”.
Jane continues that there are a number of factors to consider when choosing a ration and the most important is to determine the quality of the silage being fed, as silage forms a large proportion of the total diet.
Silage analysis shows variation in pit silage quality, consequently throughout the winter feeding period silage should be analysed and rations adjusted accordingly to ensure the diet is capable of supporting high levels of milk production. Silage quality can be categorised as good, average or poor feed value depending on analysis results as shown in Table 1.
Dry matter intake is the main limiting factor when feeding dairy cows. Freshly calved cows typically reach peak milk yield four to eight weeks sooner than they achieve maximum dry matter intakes. This imbalance is referred to as negative energy balance and causes cows to lose weight for the first 80 to 100 days of lactation. It is important to restrict this loss in body weight to 0.5kg/day otherwise it can lead to poor fertility and low milk quality.
Jane advises that “the objective of every dairy farmer should be to minimise the extent and duration of this negative energy balance by ensuring cows are fed a diet specifically formulated to complement the silage being offered”.
Typical dairy concentrates for winter feeding should include 30-45 per cent cereals (maize, wheat, barley), 15-25 per cent digestible fibre (citrus pulp, sugarbeet pulp, soya hulls), 15-25 per cent protein sources (soya, rapeseed), 15-20 per cent cereal by-products (distillers’ grains, maize gluten) and protected fats and mineral.
When the silage being fed has low intake characteristics, there is an increased risk of rumen disorders leading to acidosis and displaced abomasums in higher yielding cows. In such cases Jane recommends that the cereal content of the concentrate should be reduced to around 20 per cent and the digestible fibre content increased to approximately 35 per cent.
Jane advises that for dairy cows in early lactation the recommended crude protein of the total diet is 17 to 18 per cent. Grass silage with a crude protein content of 12 to 14 per cent should be supplemented with a concentrate containing 21 per cent crude protein on a fresh weight basis. If the crude protein of the silage is lower then a higher protein concentrate should be fed. It is important to have a balance of rumen degradable and un-degradable protein sources, for example rapeseed and soya bean.
Alternatively, it is possible to feed a lower total protein diet. Jane says that “dropping the protein level will mean you don’t get the same response out of the ration, however the cows do not lose excessive body weight, and may go back in calf quicker. The aim should be to have the cow in calf by day 85, ensuring that she will calf within the 365 day period”.
The level of concentrate feeding will be determined by silage quality, cow body condition and required milk output. Table 2 indicates suggested feed levels for cows in early lactation based on peak milk yield and silage quality.
Cows milked twice per day should not be offered more than 10kg concentrates per cow or 8kg for heifers by in parlour feeding per day. Where higher levels of meal are fed, consideration should be given to the use of out of parlour feeders, a mid-day feed on top of the silage or a feeder wagon. The risk of digestive upsets is minimised if concentrates are fed on a little and often basis.
Jane continues that the aim of any silage feeding system should be to ensure ad-lib intakes by the dairy herd allowing for a five per cent refusal. This can be achieved by good silage barrier design, feeding silage on a regular basis to ensure freshness, and being able to batch groups of cows needing special attention, such as heifers, timid cows or fresh calvers. Adequate lighting should be provided in cubicle and roaming areas to stimulate feeding.
Feeding space requirements alter according to the feeding system and may vary between 45cm and 60cm per cow. Insufficient feeding space will lower intakes and lead to more bullying, injuries and stress.
An important, but often neglected, aspect of winter feeding is the monitoring of intakes during lactation. Recording silage intakes allows potential discrepancies to be identified within a feeding system. Dairy Margin Over Concentrate tool (DMOC) can be found in DAERA online services within the CAFRE Benchmarking option. Using this simple DMOC recording system allows a farmer to measure performance on a monthly basis and enables management of the herd.
In summary, Jane recommends that dairy farmers analyse silage quality at regular intervals throughout the winter. Feed a balanced diet which complements silage quality and meets the cow’s requirements. Monitor silage intakes, milk yield and herd performance.
In the season ahead remember to focus on making high quality silage as this is one of the key factors in helping improve feed efficiency. Consider using the monthly Dairy Margin Over Concentrate online tool to monitor and improve monthly herd performance.