The fiber of forages

Relative feeding value, neutral detergent fiber, lignin.  These are all terms that can be found on any hay or grass analysis.  But what do they mean and how are they determined? 

Let's start at the beginning.  Sending in your forage to be analyzed is very important when developing a feeding plan for any species.  The values you get back tell you how the forage is lacking so that you can fill in the gaps without overfeeding nutrients that the animal won't be able to utilize.

In this post I'm going to focus on the fiber portions of forage analysis.  We'll get to protein and energy later.  Fiber in this sense refers to the structural portions of the plant cells.  The compounds that make plant cell walls rigid.  These are also the least digestible compounds in forages, thus they are important in indicating how well animals can use the nutrients in the forage.

The big three fiber categories are neutral detergent fiber (NDF), acid detergent fiber (ADF), and lignin.  NDF and ADF refer to several types of fiber and the names come from how they are analyzed.  The forage sample is 'washed' in a detergent solution, that solution is either of a neutral pH or an acid because of the chemicals used in each 'wash'.   Each of these procedures removes a set or components from the plant material, leaving only specific fiber types.  But what do they represent?

Plant cell components (image from University of Minnesota)

The neutral detergent removes soluble carbohydrates, sugars, etc.  This leaves us with only the cell wall components, lignin+cellulose+hemicellulose.  NDF value is a general indicator of intake ability.  As NDF increases voluntary intake generally goes down.

The ADF procedure removes hemicellulose, leaving only cellulose and lignin.  It is a general indicator of digestibility.  Cellulose is not digested by any mammalian enzymes, only by the microbes in the rumen of cattle and sheep or the hindgut of horses, rabbits, etc.  As ADF increases digestibility goes down.

Finally lignin, which is almost completely indigestible.  As lignin increases so does ADF and NDF, which means that both intake and digestibility go down.

Generally fiber can also be used a general indicators of maturity.  As plant age (maturity) increases the percent lignin and cellulose go up, decreasing the quality of the forage. 

That's fiber in a nutshell, what portions of nutrition do you want to hear about next?

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Nutrition and Breeding

This is a topic that has come up for me several times in recent weeks, so I thought I'd put a few notes on (virtual) paper.  Specifically, the conversations have ranged around the topic of how nutrition relates to EPDs and bull (or cow) selection.

Expected progeny difference, or EPDs are a tool used in the cattle industry to measure genetic potential.  They are a prediction of how the progeny of an animal are expected to perform relative to the progeny of other animals in the same index.  Each breed produces their own EPDs and they can't be compared between breeds without some extra math.  It sounds a bit confusing at first, but they are a great tool.

As an example: if Bull A has a weaning weight EPD of +60 and Bull B is +75, then you would expect the calves from Bull B to weigh 15 pounds more at weaning on average (this assumes comparable maternal genetics between the two calf groups).

So, where does nutrition play into this?  Well, in order for those calves from Bull B to live up to their potential they are going to need the right nutrition.  If Bull A's calves are our on lush pasture, crepe fed, and the dams are producing lots of milk, they'll grow great.  If at the same time Bull B's calves are out on poorly maintained fields with low quality grasses, the mother's milk production is going to be lower and the calves aren't going to be getting the nutrients they need to grow thier very best.  It is very asy to waste genetic potential by providing poor nutrition.

Set them both up right by balancing
genetics and nutrition.

Now, that doesn't mean that everyone needs to have perfect pastures and management.  As our extension reproduction specialist says "I don't care what your nutrition plan is, but be honest about it and pick the appropriate bull"  If I know that I'm not going to supplement my cows and calves with grain, then I choose bulls with lower frame scores, lower weaning weights, and lower milk productions (if keeping the heifers as replacements).  They don't have to be bottom of the barrel, just appropriate.  Said another way:  There is no single best bull, only the best one for each situation.

Questions?  Comments?  I'd love to hear your thoughts on the relationship between nutrition and genetics.

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The loss of paper?

 

This morning I was browsing through the ASAS newsletter and stopped to read this article.

Pros and Cons of hen lab Records Go Digital

Nothing fancy, but it gets the job done!

I found myself nodding along, agreeing with the author.  I love my paper lab notebook.  It follows me from farm to field, and back to campus for the 'real lab' work.  Everything goes in.  Even if it's just a note saying that I fed and everyone is healthy and happy.  But there are things that never do make it into the lab notebook.  There are huge data files generated from indirect calorimetry and most of our analyses, from nitrogen to VFAs to Chromium and more are done by automated machines that give you a data file, not a paper result.  Those rarely get transcribed in their entirety to the notebook.

Not the time to be trying to type.

But giving up the paper completely?  No, I can't, or won't rather, take my laptop out to the farm to record pH values on rumen fluid or rumen contents weights.  I know what my papers come back looking like after that, and it it's pretty...  I can pick up a pen when my hands are in gloves and covered in who-knows-what to jot a quick note in the book, but I'd never type on a keyboard that way.  And sometimes, those notes are crucial later when analyzing the data.

Right now, I live in a world or half paper, half digital, and that's ok.  I think I manage the balance without misplacing information or forgetting what is where.  Plus, hard copies are less likely to die in an electrical storm or coffee spill (both of which I've seen happen here)!

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The Problem of Food Waste

I've got another video for you today.  This one is from BEEF magazine about food waste.  I know I'm bad about buying things and having them get lost in the back of the fridge.  Think about that on a huge scale when you add in restaurants, groceries, and other places. 



I love the 'traffic light' sticker idea!  Do you have any good tips for minimizing food loss?  Do you compost the food that you don't use?

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Worth the Fight

Today the ag blogs have been kept busy with an idea started by Dairy Carrie.  She posted about a new song by The Departed titled Worth the Fight, which inspired her to think about how working in agriculture and agvocating was worth the fight every day, be it against the weather, animal rights activists, etc.  She asked what others in agriculture saw as worth the fight and the response has been amazing!

My roomates.

When I got to thinking about what was worth the fight, my mind went to the fact that I start a new round of experiments next week.  I love my research, but this round will involve being at the farm round the clock for ten days.  I'll be getting up every three hours every one of those nights.  I'll be eating out of a microwave again.  I'll see my steers more than my husband, since he'll be taking care of the house and the dogs.  We'll communicate by phone and email only.  I'll sleep on a cot that's far less comfortable than my bed.

 

I'll miss these crazy girls!

But every bit of that will be worth the fight against being tired, lonely, and uncomfortable.  At the end of it all I'll be the first to know how fescue toxicosis changes energy use and digestion in cattle.  That's an amazing feeling.  Then, I'll get the chance to tell others what I've larned and use the information to help farmers and ranchers in the southeast produce better cattle on their fescue pastures.

For me, increasing scientific knowledge and providing information to help cattle rachers is #worththefight.

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