It is fast approaching spring calving once again and as day light hours increases, hopefully grass growth will increase also. Undoubtedly grazed grass is our most cost effective feed on Irish farms and it should be maximised, however it must be recognized that grazing grass diets will only support approximately 19 – 20 Litres of milk. Therefore, in higher yielding herds grazed grass must be supplemented to avoid a negative energy balance in the dairy herd which carries huge herd issues long-term.

The main objective in feeding cows is to meet the energy requirements of the cow as efficiently as possible. If total energy intake is reduced at any stage during lactation milk proteins drops. A major drop in protein % and/or low milk protein (below 3%) can be an early warning that cows are underfed and corrective action should be taken quickly to avoid subsequent fertility issues.

There are a number of potential reasons why cows may be underfed in early lactation including: –

• Feeding poor quality silage which has a low DMD value and poor UFL value
• Overestimation of grass intakes  in early lactation – poor grass growth or perhaps poor grazing conditions (wet paddocks) contribute to over estimation
• Concentrate supplementation can be reduced too quickly in spring due to over -estimation of grass

It’s important to maintain concentrate feeding levels to match grass growth. Feeding a high starch concentrates will also aid milk protein production.  Minimising body condition loss is important between calving and start of breeding – maximum BCS loss should be 0.5. High levels of supplement feeding  are required when grass production is low and milk production is high. In reality many cows don’t receive high levels of concentrate which effects:

1. Production is reduced
2. Fertility issues are increased
3. Extended calving interval

Even though grazed grass is the most economical way to feed cows, supplementing with concentrates when grass is tight or grazing conditions are poor, is necessary and cost effective in the long run. As well as an increase in milk yield it is a guaranteed way of supplying magnesium in the diet and other essential mineral and vitamins that are essential for herd health and fertility. A simple rule of thumb when deciding on concentrate supplementation should be

(Milk yield – 20) x 0.50 = Kg concentrate fed

Recommended concentrate feeding level for spring calving herds peaking at 28Litres (2Kgs Solids)

 

Summary

1. Energy is the golden ticket to a successful grazing season – so make sure your cows are being fed enough to avoid energy deficits which can lead to a string of problems long term.
2. Measuring grass is the only sure way you have of knowing that your cows are getting the correct amount of grazed grass.
3. Monitor your milks solid levels continuously they will quickly give you signs if there is something wrong.
4. Speak to your nutritionist and get them to run a diet formulation for you so you can be assured that you are feeding the correct concentrate
5. If you are feeding forage in the early spring make sure its analysed so you know exactly what quality it is and balance accordingly
6. Feeding concentrates have the added benefits of providing magnesium  and other essential minerals to cows at grass

Valerie Hobson B.Agr.Sc (Animal Nutritionist) Quinns of Baltinglass Ltd, Mainstreet, Baltinglass, Co. Wicklow