Getting the correct balance at grass

Remember as we approach the breeding season, low protein in your herd's milk is an indication of a negative energy and will lead to low conception rates, warns ruminant nutritionist Brian Reidy

There is no doubt grass is the cheapest feed we have in Ireland for milk production, but sometimes it does not work out perfectly, and we must be prepared to take action due to its inconsistent nature depending on weather, etc.

The recent spell of beautiful weather has thankfully kick-started grass growth, and you can almost see the grass jump out of the ground. For many, this will mean a surplus will be created very quickly. In a normal year, a high proportion of dairy herds would be grazing by day and night from the middle of March, whereas this year that has only become commonplace in the last two weeks or so, due to poor growth earlier in the spring.

Getting profitable performance from your herd

Let’s look at the spring from the cow’s point of view. How much grass can she eat in a day? What is the quality of the grass? What milk volume and quality can grass support? How much grass is required for the cow’s maintenance? What is in excess and what is deficient in the grass she is eating?

Do the changes in weather affect a cow’s intake and utilisation of energy from day to day?

There is no doubt grass is the cheapest feed we have in Ireland for milk production, but sometimes it does not work out perfectly, and we must be prepared to take action due to its inconsistent nature depending on weather, etc.

What do cows get consistently from grazed grass?

When grass is in good supply, many dairy producers are tempted to reduce or even stop supplementary feeding. This can bring short-term improvements in margins. 

The cows may continue to milk satisfactorily for a period of time after, with any reductions in milk yield justified on the basis margin per cow will be increasing due to the use of cheaper grass. Some of these short-term gains may be hiding longer-term losses in performance, unfortunately. 

Initially, the cow may continue to milk well, but this could often be at the expense of increased body tissue loss. In the best grazing conditions possible, when feeding no supplementary feed, grass intake is unlikely to exceed 18kg/day (about 3% of the cow’s body weight). 

There are, however, many situations when grazed grass will not achieve more than 14kg DM intake a day, when grass quality, grass cover and weather are not ideal. When you feed a concentrate to cows on grass, then grass intakes are likely to decline if over-supplementation occurs — however, if supplementation is used to bridge a gap between known intakes and actual energy requirements, then an excellent economic response will be achieved. With current milk prices, it is crazy not to optimise dry matter and energy intake. 

Replacing cheap grass with more expensive concentrates should never be the goal. Concentrates and forages should always be fed to complement available grass intakes. This way, you will produce quality milk, maintain fertility performance, improve longevity and body condition. Remembering every litre you produce makes a profit add to your bottom line.

Milk yield, solids and cow health

Milk supply per cow is up this spring on many farms. This is multifactorial from farm to farm, with a strong milk price a later nighttime turnout and the recent good weather all contributing. Cows getting more energy and dry matter are always under less stress and this will also contribute to improved milk solids. The message is very simple: you must have good quality forage in the yard to get cows off to the very best possible start.

Milk solids — how can you influence them?

Milk solids are not all about genetics — you must feed them well for the genetics to be expressed. Look and listen to your cows. If solids are dropping, then energy and fibre intake is insufficient. This may be due to grass being too strong and of poorer quality or due to underfeeding of supplementation at grass. 

It may, however, be due to the too rapid throughput of grass through the cow’s digestive system, particularly as many start the second round, and covers are low and lush. For cows to maximise their production from grass, it needs to remain in the rumen long enough to be thoroughly digested. 

Keep an eye on the consistency of the dung. Loose dung is not because of wet grass. When dung is excessively loose, it is generally due to low physical fibre levels in feed and an excessive protein intake. Remember for a cow to function efficiently, she must maximise cud-chewing activity to process her feed into milk.

If she eats material which is soft or of small particle size, then what will she chew on? Can you get some fibre into your cows easily? It can be a big help! On the issue of excessive protein supply, it must be borne in mind that during the spring and summer months, grass will rarely drop below 23% protein and may reach as high as 30%. 

With this in mind, I see very little reason why a concentrate in excess of 13-14% would be fed to cows that are at pasture full time. The total protein requirement of a dairy cow is generally between 16% and 17%, depending on the level of production. A good rule of thumb is 100g of protein per litre produced. Use milk urea levels to guide you when deciding how much protein to supplement.

Remember as we approach the breeding season, low protein in your herd's milk is an indication of a negative energy and will lead to low conception rates. Increase milk protein and more cows will go in calf.