Beyond knowing the nutriet composition of forages it is also important to be aware of harmful compounds that may be in feeds and forages. Here's a good article on both how and why we need to take extra care to test in drought years like this one.
http://www.agweb.com/article/test_cornstalk_bales_twice/
Showing posts with label feeding. Show all posts
Showing posts with label feeding. Show all posts
Monday, 15 October 2012
Wednesday, 10 October 2012
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?
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?
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?
Monday, 1 October 2012
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.
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.
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.
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. |
Questions? Comments? I'd love to hear your thoughts on the relationship between nutrition and genetics.
Monday, 27 August 2012
Feeding the Rumen
Warning: I'm going to try to keep this simple, but it's not an easy subject once you get past the intro. Feel free to ask questions if you want clarification or more info, I'm happy to to explain anything in more depth.
I come across articles about feeding cattle fairly regularly on various news agencies. More so in the past few months than usual, probably due to the drought this summer and concern over food costs. Each time I do, I try to make my way through the comments to see how people are responding and what they think. Almost every time I see several comments in the vein of "cattle should only eat grass not [grain...candy...byproducts...etc]."
While there is a whole host of reseach out there about the differences between grass and grain fed beef, that's a dscussion for another day. And one I'm more than willing to have. You might be suprosed about this beef nutritionist's thoughts. (Hint: I like both and think they both have a place).
The bigger point for me here comes when comments like the example above are followed by some statement about how the cattle need the grass because the other feed is unhealthy or not natural. And this my readers is where we dive back into the rumen.
The rumen basically just functions as a fermentation tank for a plethora of microorganisms. Bacteria, fungi, and protozoa love that place! One of the first tenets of feeding cattle (or any ruminant) is that you aren't. What you are doing is feeding the microbes. The microbes digest the food the cattle eats, turning it into the nutrients the animal absorbs and utilizes for energy, muscle building, etc.
Now, I'm not saying that we can't alter the microbial products by altering the diet. We can and do. But, the microbes are not overly particular about the form of their nutrients. They really just want the carbon and nitrogen and other elements to pull off for their own needs. Everything else is waste, which is rearranged by a series of reactions into a fairly standard set of molecules that the cattle then use.
This is where that warning comes in. This is a whole semester of ruminant nutrition as short and sweet as possible.
For example: Let's say I feed my cow some grass. The microbes don't really care that it's grass. They digest the cellulose and other starches to get into the center of each tiny cell in that grass. That's where the good stuff is. Proteins, amino acids, and so much more. When the cellulose is broken down it is rearranged into several products. The most important of which are volatile fatty acids (especially acetate, propionate, and butyrate). These are the main players for energy in cattle.
The big picture here is that the microbes don't care about the original source of the carbon and nitrogen they stick back together to make VFAs. It just happens. You or I can eat meat or beans. The proteins from either get broken down to amino acids either way. The microbes in the rumen are similar, they just happen to break down materials that you and I never could becuase they have a different set of enzymes.
As always, there is my caveat that this is not a simple process. The diet fed to cattle still has to have the right balance of proteins, carbohydrates, minerals, vitamins, etc. Without that we do end up with unhealthy animals. No one wants that. I and every farmer I know hates having sick animals. We feel for them when they are hurting. But we can continue to create that balance using unusual feeds to provide safe, healthy meat; when they are available, cost effective, and fit the needs of the animals and producer. If they don't go to cattle or other animals, they go to the land fill. At least this way the waste fills a niche and leaves more corn, wheat, etc for straight human use.
That's my 5 minute ruminant nutrition lesson for the week, thanks for stopping by. As always, let me know if you want more!
I come across articles about feeding cattle fairly regularly on various news agencies. More so in the past few months than usual, probably due to the drought this summer and concern over food costs. Each time I do, I try to make my way through the comments to see how people are responding and what they think. Almost every time I see several comments in the vein of "cattle should only eat grass not [grain...candy...byproducts...etc]."
While there is a whole host of reseach out there about the differences between grass and grain fed beef, that's a dscussion for another day. And one I'm more than willing to have. You might be suprosed about this beef nutritionist's thoughts. (Hint: I like both and think they both have a place).
 |
| Rumen diving at it's finest. |
The rumen basically just functions as a fermentation tank for a plethora of microorganisms. Bacteria, fungi, and protozoa love that place! One of the first tenets of feeding cattle (or any ruminant) is that you aren't. What you are doing is feeding the microbes. The microbes digest the food the cattle eats, turning it into the nutrients the animal absorbs and utilizes for energy, muscle building, etc.
Now, I'm not saying that we can't alter the microbial products by altering the diet. We can and do. But, the microbes are not overly particular about the form of their nutrients. They really just want the carbon and nitrogen and other elements to pull off for their own needs. Everything else is waste, which is rearranged by a series of reactions into a fairly standard set of molecules that the cattle then use.
This is where that warning comes in. This is a whole semester of ruminant nutrition as short and sweet as possible.
For example: Let's say I feed my cow some grass. The microbes don't really care that it's grass. They digest the cellulose and other starches to get into the center of each tiny cell in that grass. That's where the good stuff is. Proteins, amino acids, and so much more. When the cellulose is broken down it is rearranged into several products. The most important of which are volatile fatty acids (especially acetate, propionate, and butyrate). These are the main players for energy in cattle.
 |
| I know here's a lot going on in this image. Sorry, it's just not easy to find a good, clear graphic. The relevant part for this post is up at the top. Click to see the original in full size. |
As always, there is my caveat that this is not a simple process. The diet fed to cattle still has to have the right balance of proteins, carbohydrates, minerals, vitamins, etc. Without that we do end up with unhealthy animals. No one wants that. I and every farmer I know hates having sick animals. We feel for them when they are hurting. But we can continue to create that balance using unusual feeds to provide safe, healthy meat; when they are available, cost effective, and fit the needs of the animals and producer. If they don't go to cattle or other animals, they go to the land fill. At least this way the waste fills a niche and leaves more corn, wheat, etc for straight human use.That's my 5 minute ruminant nutrition lesson for the week, thanks for stopping by. As always, let me know if you want more!
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