Protein levels in grazed grass

[DairyNerd]

Had two grass samples back today. Current field cows are in 11ME, 14.5 protein. Next field to graze 11.7ME, 17.5 protein. I knew current field wasn't so good, but needed to graze it, was cut for first cut, still a bit suprised the protein was that low but has grown back slowly and got a bit far on. Milk Ureas got low which is why i did the samples, milk has also dropped a bit too.

Questions:

Would you be worried about these levels of protein? Cows are freshly calved and getting 1.5kg cake a day at 16%.

Next fields in the rotation should be better but i feel like 17.5% isnt that high really for grass at 2800-3000, just wondered about people's thoughts on it really.

 

[jerseycowsman]

Had two grass samples back today. Current field cows are in 11ME, 14.5 protein. Next field to graze 11.7ME, 17.5 protein. I knew current field wasn't so good, but needed to graze it, was cut for first cut, still a bit suprised the protein was that low but has grown back slowly and got a bit far on. Milk Ureas got low which is why i did the samples, milk has also dropped a bit too.

Questions:

Would you be worried about these levels of protein? Cows are freshly calved and getting 1.5kg cake a day at 16%.

Next fields in the rotation should be better but i feel like 17.5% isnt that high really for grass at 2800-3000, just wondered about people's thoughts on it really.

We’ve had a sample back today, was pre mowed and eaten 3 weeks ago and then had 20 units of N. That is 12ME and 23% protein and about 4500 kg DM.
Everyone will say that’s to high covers, but I do what I think is right, don’t care what everyone else says!
Cows are averaging 24 litres a day at 5.1 and 3.5.

 

[jerseycowsman]

Our urea’s have been low throughout, we normally feed a 14% nut, but been on a 16 all season so far

 

[DairyNerd]

We’ve had a sample back today, was pre mowed and eaten 3 weeks ago and then had 20 units of N. That is 12ME and 23% protein and about 4500 kg DM.
Everyone will say that’s to high covers, but I do what I think is right, don’t care what everyone else says!
Cows are averaging 24 litres a day at 5.1 and 3.5.

Cant really argue with that! Were were doing 24L at 4.6 and 3.8 which i was happy with, dropped to 22 at 4.3 and 3.6 now but we have had several heifers go in the tank which has bought the average down. All on 1.5kg cake. Calve April, May and June so hopefully average still rising as fresh calvers not peaked yet.

I go round after the cows with 20-25kg per hectare N, this field didnt have so much for first cut so wondered if it is lack of nitrogen.

 

[DairyNerd]

We’ve had a sample back today, was pre mowed and eaten 3 weeks ago and then had 20 units of N. That is 12ME and 23% protein and about 4500 kg DM.
Everyone will say that’s to high covers, but I do what I think is right, don’t care what everyone else says!
Cows are averaging 24 litres a day at 5.1 and 3.5.

Do you always graze covers that high and always pre-mow?

 

[lazy farmer]

We’ve had a sample back today, was pre mowed and eaten 3 weeks ago and then had 20 units of N. That is 12ME and 23% protein and about 4500 kg DM.
Everyone will say that’s to high covers, but I do what I think is right, don’t care what everyone else says!
Cows are averaging 24 litres a day at 5.1 and 3.5.

So it’s grown 150 a day for 20 days ?

 

[jerseycowsman]

So it’s grown 150 a day for 20 days ?

No, it’s pre mown down to 2300

 

[jerseycowsman]

Do you always graze covers that high and always pre-mow?

Yes, usually graze much higher covers than what the experts say I should. Not always pre mow though, always do one round of pre mowing through may, then some times another through late July August

 

[ollie989898]

Cant really argue with that! Were were doing 24L at 4.6 and 3.8 which i was happy with, dropped to 22 at 4.3 and 3.6 now but we have had several heifers go in the tank which has bought the average down. All on 1.5kg cake. Calve April, May and June so hopefully average still rising as fresh calvers not peaked yet.

I go round after the cows with 20-25kg per hectare N, this field didnt have so much for first cut so wondered if it is lack of nitrogen.

Low N may be the cause, though a shortage of other nutrients may also be to blame for low protein levels.

There is generally a lot of protein in grass silage, but much of it is crude protein, which will be raw material for the biota in the rumen. The cow herself will not see all of this crude protein by any means- the bugs will have noshed it before she gets a look in.

Crude protein acts as the 'throttle pedal' in a cow. Everyone is familiar with feeding their cow some mega diet all winter only to see the milk output shoot up the second cows get let out in spring. The more crude protein you feed, the more the bugs party and to a general extent the faster fermentation in the rumen occurs- more bugs means a bigger workforce to recruit to digest all the incoming fibre. The trick is to make sure that the cow is fed enough fermentable energy to keep up with the bugs demands and also has a diet which looks after her demands as well. Which is why, in theory, lower protein diets are fed to cows and the digestible fibre level is bumped up. For example: you would switch out maize gluten from a diet in favour of sugarbeet instead. In energy terms, there probably isn't much difference between the two. The difference is in their crude protein and digestible fibre fractions to slow the bugs down a bit but sustain milk production all the same.

 

[Farmer Keith]

No, it’s pre mown down to 2300

Can you not get your mower lower than that? You’ve just raised the plants growing point way off the the ground. I think I’m right in saying your 4500 will be the equivalent of a standard 3700 given that your residual is set so high?

 

[DairyNerd]

Low N may be the cause, though a shortage of other nutrients may also be to blame for low protein levels.

There is generally a lot of protein in grass silage, but much of it is crude protein, which will be raw material for the biota in the rumen. The cow herself will not see all of this crude protein by any means- the bugs will have noshed it before she gets a look in.

Crude protein acts as the 'throttle pedal' in a cow. Everyone is familiar with feeding their cow some mega diet all winter only to see the milk output shoot up the second cows get let out in spring. The more crude protein you feed, the more the bugs party and to a general extent the faster fermentation in the rumen occurs- more bugs means a bigger workforce to recruit to digest all the incoming fibre. The trick is to make sure that the cow is fed enough fermentable energy to keep up with the bugs demands and also has a diet which looks after her demands as well. Which is why, in theory, lower protein diets are fed to cows and the digestible fibre level is bumped up. For example: you would switch out maize gluten from a diet in favour of sugarbeet instead. In energy terms, there probably isn't much difference between the two. The difference is in their crude protein and digestible fibre fractions to slow the bugs down a bit but sustain milk production all the same.

Thanks. P and K's were good across the farm when last samples were done in 2019 and the platform was not cut by the previous farmer as he had a fair bit of off ground. Only started milking here in April so probably a good idea to do some up to date ones.

I have been a bit tight with the fertiliser in there as it was not grazed before first cut so was further on than the rest. I'm spreading AN 34.5%, do people think that would make any difference vs Urea if spread at the same rate?