Author Topic: Cause and effect of low pH in cow's milk  (Read 875 times)

Offline lead_dog

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Cause and effect of low pH in cow's milk
« on: June 01, 2013, 10:39:35 AM »
We milk a small herd of cows (seasonally) and make raw milk cheese. We're about 2 months away from ending this year's production, so, on average, the cows are in the 6th month of lactation. All are confirmed bred and the vet gave them a good check up last week. Bulk tank SCC is about 180,000.

For the past 3 makes, the pH of the milk itself has been very low...6.4-6.5. As a result, I've reduced the starter culture for the aged cheeses I'm making (Alpine and Cheddar, both aged 6-10 months). Still, my pH on the most recent make tanked to 4.3. The one before that was 4.5.

I'm struggling with two questions:

1. What could be causing the pH to be so low to begin with? Our cleaning systems are excellent (pipeline, 160 degree water, triple dip cows, etc.).
2. What impact (flavor, texture, etc.) will the low initial pH of the cheddar have once it completes aging? Should it age shorter, longer?

Thanks if you have any input.


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Online Alpkäserei

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Re: Cause and effect of low pH in cow's milk
« Reply #1 on: June 01, 2013, 12:04:13 PM »
Diet, water, what are they getting access to?

If your diet is not properly balanced, can push the pH off in the milk -this also affects enzyme balance and bacteria cultures in the milk which in turn affect how it acts when you make it into cheese. 
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Offline lead_dog

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Re: Cause and effect of low pH in cow's milk
« Reply #2 on: June 01, 2013, 01:27:48 PM »
On pasture 24 hours a day. Moved to fresh paddocks twice weekly.  In addition, 7 pounds per day each of 16% dairy ration. Fresh, well water at all times.

Offline Back 2 The Frotture

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Re: Cause and effect of low pH in cow's milk
« Reply #3 on: June 01, 2013, 02:19:07 PM »
Pickles, balsamic vinegar, and tomato juice are all around ph 4.3.  What can you say about the flocc time or the curd's taste?  Recalibrate and check ph at all stages of production.  One possibility is that the tank was not rinsed properly and sodium hydroxide (if used) was left on the tank walls.  I'd taste a crumble now, but just a crumble.

Offline WovenMeadows

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Re: Cause and effect of low pH in cow's milk
« Reply #4 on: June 01, 2013, 02:41:27 PM »
Is the milk getting cooled quickly enough? If it is staying warm for too long, any adventitious lactic-acid bacteria in the milk could start dropping your pH before you go to make cheese. But this wouldn't affect a lower-than expected final pH, I don't think.

Second, whereabouts are you? This time of year we had a lot of lush spring growth. The plants are high in sugars and easily digestible, and production is high. Not sure if this makes for a sweeter-than-normal (more lactose present) milk, but often protein and fat % can be lower as well. More lactose and less casein and calcium would lead to more acid development, I think. If you graze rotationally, did they move into a new paddock with a rather different plant composition?


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Re: Cause and effect of low pH in cow's milk
« Reply #5 on: June 01, 2013, 05:44:47 PM »
I'd suggest a full audit of you operation, if this problem is causing failure and loss of product.

Do you sell your cheese? What grade is your dairy inspected for? Regardless, I recommend you try and meet grade A standards.

Examine every step of the operation, and find anything that MIGHT cause a problem. Fix it, and try again. If such an attempt still doesn't fix the problem, then I'd say you need mineral supplements for your cattle, they're not getting something they need. (family in the feed business for generations, I know a thing or 2 about what mineral deficiencies can do to dairy)

Have your milk chemically tested -not just the mandatory population tests, but chemical tests. might cost money, but it can tell you just what you need to be giving your cows.

Grass fed is great and I'm all for it, but cows are not native to this continent and their digestion is not balanced to strictly forage  off of our grasses -that and you are limited what and where they can go. So bottom line is, they need supplemental minerals to keep things balanced.

Also, probably you know this, but keep them off of the early morning grass. You don't want them eating the dew, this can cause digestion trouble as well, leading the chemical imbalances in the milk
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Offline lead_dog

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Re: Cause and effect of low pH in cow's milk
« Reply #6 on: June 01, 2013, 06:27:13 PM »
We are Grade-A. It's not the cleaning system or cooling. It's the milk. I took the pH from this evening's milk and it was 6.48, straight out of the cows. This was from collecting the 1-2 gallons that drain below the receiving jar that doesn't get pulled through the pipes.

Offline linuxboy

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Re: Cause and effect of low pH in cow's milk
« Reply #7 on: June 01, 2013, 07:01:53 PM »
What does your trace mineral and salt supplement look like? Also, can you steal some cud and test its pH?
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Offline lead_dog

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Re: Cause and effect of low pH in cow's milk
« Reply #8 on: June 01, 2013, 07:05:02 PM »
I feed Thorvin kelp in the mailing parlor. Good idea on the cud.

Offline linuxboy

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Re: Cause and effect of low pH in cow's milk
« Reply #9 on: June 01, 2013, 08:02:29 PM »
Nothing else except the kelp? What's the pasture blend that's growing? It might be something basic like deficient cobalt or copper, or not enough calcium. Lower pH with healthy cows often is due to low solids or protein issues. So if your protein balances out at 14-18% of high quality in the feed, and rumen pH is within normal range (5.5 to about 6.4), I would check trace minerals next. If milk protein is good but pH is off, may need to buffer rumen pH or try to adjust the ration.
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Offline lead_dog

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Re: Cause and effect of low pH in cow's milk
« Reply #10 on: June 01, 2013, 08:11:42 PM »
Yes, only kelp. There sre some minerals in the bit of feed they get but I'm not sure what. I can check on Monday. They've been grazing a good mix of crimson clover, ryegrass, fescue, chicory with some Bermuda and crabgrass now starting to come in also. They are on pasture 23 hours a day.

My yields have been increasing (14% on yesterday's cheddar!). I'm not surprised since we're getting later in lactation, but I figured the higher yields I've been getting would correlate with more solids.

Unrelated to cause, I'm very curious what you think the effect of the initial pH will be on the end product if I age the cheddar 9-12 months. My target pH was about 5.0 but bottomed out at about 4.3. The wheels are now bandage wrapped and caved.

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Re: Cause and effect of low pH in cow's milk
« Reply #11 on: June 01, 2013, 08:15:09 PM »
I concur with LB, if you have proven it is not in your processing system somewhere, it is the diet.

Those cows need minerals. You can find organic supplements to give them, but they need minerals. Even in the Alps, we would give the cows mineral supplements to maintain a proper balance.

And also, some roughage is needed. Do your cows have access to hay or straw? Believe it or not, they are not going to get enough roughage from the grass.

I would suspect first off that there may be a calcium deficiency.

At the feed mill, we always had to add selenium beyond what was normal, because the Indiana  grasslands have a selenium deficiency. Pasture grazed animals here need high levels of manganese, magnesium, copper, and selenium (a few others to) because these are lacking in the local grasses. We have plenty of calcium, iron, etc.
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Offline linuxboy

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Re: Cause and effect of low pH in cow's milk
« Reply #12 on: June 01, 2013, 08:52:46 PM »
Higher yields are not surprising. Hot weather often means less water intake, so more concentrated milk. More roughage means more fat % in milk. Plus later lactation. All comes together. Try a few cows with a really bioavailable loose mineral supplement that has good calcium levels (one where the first ingredient is not salt, or if it is, the salt content is not super high). If their milk improves, you can tell right away that's what it is.

Like Alp, I have to supplement with selenium (BoSe injectable as point-of use on young borns to help them bounce faster, or the dams before kidding), and also copper, in addition to a broad loose mineral.
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Offline linuxboy

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Re: Cause and effect of low pH in cow's milk
« Reply #13 on: June 01, 2013, 09:05:04 PM »
Quote
Unrelated to cause, I'm very curious what you think the effect of the initial pH will be on the end product if I age the cheddar 9-12 months. My target pH was about 5.0 but bottomed out at about 4.3. The wheels are now bandage wrapped and caved.
Generally, more crumbliness. But I'd need to see the entire make log and pH curve, and milk components, and final cheese components (FDM, MFFB, salt) to tell you better. pH by itself doesn't say all that much.
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