Saturday, April 2, 2011

Some Mammals Require Dietary Carbohydrate

But they’re ruminants, and we aren’t

I’ve been busy since the last post. I’m grateful for the opportunities I’ve been given, but it is a challenge! I made a commitment (dare I say a “resolution”?) to post items to this blog on the 1st and 15th of each month. Looks like I’ll miss this one by just a bit. I’ll try to get back on track for the next post, although the next few weeks will include presentations at the Douglas County Livestock Association’s Spring Livestock Conference on April 9th in Roseburg, Oregon and at the Small Farm Trade Fair in Madras, Oregon on April 16th.

Since my last post I’ve given a presentation, attended a conference, and tried to work my way through a couple of books. And I’m constantly being reminded of just how much we have to do to before “the system” is fixed.

I spoke to the Crook County Stock Growers Association’s Annual Banquet on March 19th. The event was held at the at the Crook County Fairgrounds in Prineville, Oregon. The well attended event was, in part, a fund-raiser for their Beef For Kids initiative. They are striving to get good-quality, locally-grown beef back on the menus of Crook County public schools. A truly worthy goal. I know that the cattlemen in Malheur County are already engaged in a similar initiative, and I hope we’ll see this effort spread throughout the nation. The “food” we provide to our school children via our school meal programs is truly abysmal. And the chance to repeat the message, in various ways, that animal products are fundamental to human health should never be missed. My presentation, “Food For Thought,” was well received. Several folks kindly shared their personal experiences with me. I was grateful that I could again direct people to the sources of information that have so profoundly changed my own life. Eventually I found myself standing in the dinner line next to a long-time friend. Suddenly I became aware of one of the paintings that were hung on the wall over the pass-through from the kitchen. Oh, the irony!
Figure 1:How to fatten a hog, and a human!
I also attended the Oregon Forage and Grassland Council’s 2011 Annual Meeting in Albany on March 24th. This year’s keynote speaker was Neil Lane, an Australian dairy farm management consultant from Intelact. He shared a wealth of information about pasture-based dairy management in Australia and New Zealand. What he tried to impart to us can have an immense impact on the Pacific Northwest. Our environment is unique to North American. The potential for grass-based animal agriculture in our region is huge. We have progressive grass farmers here, but there’s room for many more!

“We don’t manage paddocks – we manage tillers!”
                                                                                  - Neil Lane

Now a clump of perennial ryegrass might look like a single plant, but it’s actually a collection of tillers. While each tiller has its own leaves and roots, it is connected to neighboring tillers at its base. These tillers share water, nutrients and carbohydrates via this connection. A newly-established ryegrass plant consists of one tiller until it reaches the 3 leaf stage. If there is a low tiller density, sunlight will penetrate to the base of the sward. This stimulates the production of daughter tillers. These daughter tillers grow from buds in the leaf axil, appearing first as small one leaf tillers growing inside an older leaf at the base of the plant. This older leaf soon dies and disappears. The new tiller continues to put out leaves and soon becomes a separate tiller with its own root system. Each new leaf emerges on the opposite side of the tiller to the previous leaf.
Figure 2. A ryegrass tiller with 3 1/2 leaves (from Guest, 2008)
A perennial ryegrass tiller maintains a maximum of 3 live leaves. As each new leaf emerges after this 3 leaf stage, the oldest leaf dies. Maximum perennial ryegrass yield is achieved by allowing the tillers to grow to 3 leaves as each subsequent leaf is bigger than the previous leaf. The 1st leaf contributes 15–20% of total pasture biomass, the 2nd leaf 30–35% and the 3rd leaf 45–50% with little difference in metabolizable energy content between the 1st and 3rd leaf (Figure 3).
Figure 3. Leaf stage vs. yield (from Guest, 2008)
Provided water is not limiting, leaf growth rate is controlled mainly by temperature. Perennial ryegrass will usually grow a new leaf every 6–7 days in the warm, sunny days of early fall, but could take 10–13 days or more in the colder, shorter days of mid to late fall.

Tillers form glucose and then other water soluble carbohydrates (WSC) in the leaves via photosynthesis. These WSC (also known as Non-Fiber Carbohydrates, or NFC) are used to provide energy for ongoing growth and respiration. The availability of WSC in ryegrass tillers has a marked effect on the plant’s re-growth potential and ability to persist after grazing. When the fourth leaf emerges and the oldest leaf dies, there is no further build up of plant WSC levels (Figure 4). Proper grazing management must take into consideration this relationship to promote improved utilization and production. Improved pasture utilization and production will lead to optimal profit.

Figure 4. Leaf stage and water soluble carbohydrate levels (from Guest, 2008)

Studies have shown that it is best to use leaf appearance intervals
to decide when to graze, not pasture height.
- Kelly Guest, 2008

Grazing at the 3rd leaf stage doesn’t just improve pasture production and utilization. It also improves animal performance. Proper rumen function requires at least as much NFC as Ruminally Degradable Protein (RDP) in the herbage eaten. If there is too much RDP, it is converted to ammonia in the rumen. This excess ammonia needs to be detoxified to urea and excreted in urine. This process requires energy, and can have a negative effect on both production and reproduction in the grazing animal. Green growing pasture contains more than enough RDP for any ruminant’s requirements, but the NFC are frequently limiting. Recent research has shown that the ratio of RDP to NFC becomes more balanced after the 2-leaf stage, as NFC levels increase with re-growth, while RDP levels decline due to leaf maturity. The ratio of RDP to NFC can be as high as 5:1 at the 1st leaf stage, declining to 1:2 at the 3rd leaf stage. The levels of minerals in perennial ryegrass change markedly with re-growth, too. Potassium, which is usually at levels far in excess of the animal’s requirements, declines, while calcium and magnesium, important for milk production, increase with re-growth to the 4-leaf stage. One indicator of appropriate mineral status for performance of dairy cows is the ratio of potassium over calcium and magnesium. This ratio should be below about 2.2 to reduce the incidence of grass tetany and other metabolic problems. The ratio falls from about 6 at the 1st leaf stage, to below 2.2 at the 3rd leaf stage. Another indicator of appropriate mineral status is the ratio of calcium to phosphorus. The recommended ratio for milking cows is above about 1.6:1. In perennial ryegrass this ratio changes from about 1:1 at the 1st leaf stage, to over 2:1 at the 3rd leaf stage.

Table 1. Nutrient values of perennial ryegrass herbage at different leaf stages. (Donaghy, 2005)

There is abundant evidence of farmers increasing their profitability by using leaf stage for grazing management. But new ideas aren’t always embraced by the farming community. If the New Zealanders are lagging in their adoption of this philosophy, as Neil told us, then how long will it be before it’s adopted in the US? Seven-plus dollar a bushel corn may help the adoption rate!

Figure 5: Spring in Western Oregon

Donaghy, D. and B. Fulkerson. 2005. ‘Principles for developing an effective grazing management system for ryegrass-based pastures’. Press release Dairy Research and Development Corporation, Tasmanian Institute of Agricultural Research.

Guest, K., 2008. “Pasture Phase Farming – More Than a Passing Phase: A Handbook to Ryegrass Management on the Esperance Sandplain.” Lemon, J., J. Ryan, M. Ryan, N. Witham, and J. Lucey, Eds. South East Premium Wheat Growers Association.


  1. Interesting Pete! Keep 'em coming!

  2. Thanks, Fred. I appreciate the encouragement.

  3. Pete nice work would love to see a lot more.


  4. Thanks, Andrew. I plan to keep at this for as long as I can!

  5. Yes Pete, thank you for your contributions! Together, we all might just change this world my friend.

  6. You're welcome, Misty. And thank you for yours! Together, indeed! There's SO much to do ...

  7. Sorry if this is OT for this post:
    Love your blog! It really seems mostly figured out for the various ruminants. Their proper natural diet is something we can accomplish through proper management, with pasture/permaculture systems, for healthier meat and a healthier environment. Now we just need experts or scientists like you, and consumers and dilettante farmers like me, to spread the word. But what about some non-ruminant species? I'm trying to figure out what to do to feed chickens, ducks, and pigs without all the corn and soy. I put the chickens and ducks out on pasture, but if you're raising a couple hundred of them, it's hard to do without corn and soy. They can't just eat grass, and there aren't naturally enough bugs out there for them. Do you know of any sources on feeding practices for these species? Corn and soy, other grains, aren't really a natural diet for chickens, either, and result in too much n6 in their fat, I expect. I'm thinking of trying a black soldier fly system this summer as an experiment, for fat and protein for chickens. I'm in zone 4, so outside the black soldier fly's natural range, but may be able to keep a colony going in a screened hoophouse, or something. Crank it up for the summer, and slow it down in winter to just support some layers. Just wondering whether you know much about these issues, or know of people working on them.

  8. Hilary - Do you have access to one of the older editions of "Forages: The Science of Grassland Agriculture" by Heath, Metcalfe and Barnes? It's a standard college textbook. Chapter 64 in the third edition is "Pasture for Swine and Poultry." If you can't find the book at your local libaries, I have a pdf copy of that chapter. Send me a e-mail - dulcimerpete "at" hotmail "dot" com. Might give you some ideas. Apparently geese are the best poultry for utilizing pasture. Joel Salatin at Polyface Farm practices multi-species grazing with the laying chickens following the beef cattle, with the hens eating the fly larvae from the cow pies. Pigs have been fattened on acorns and other nuts for centuries - forest grazing. May not be able to completely eliminate grain feeding, but will be able to reduce it. I'll look into this some more.

  9. Thanks for the ideas! I'd really appreciate that chapter 64 pdf. Not much in the way of libraries around here. Definitely interested in pastured swine. We've raised a few pigs on hay and reject cheese, which we were able to get by the pallet load, free, from a large dairy cooperative. They seemed to do well, but out on fresh pasture would be better. I've definitely noticed that geese will crop the grass even closer than sheep. I'm somewhat familiar with Salatin. We only have five or six acres of pasture, though, and at this point aren't raising beef for the chickens to follow. I also don't like his pasture-pen system. We've done plenty of pasture pens, but have decided it's too labor-intensive, and too confining for the birds. I end up needing to move the pens twice a day, because if they graze and shit in one place all day, you don't want them having to settle down and sleep in it, so you move it in the evening. But then you want to move them to fresh grass also in the morning. And I don't think they can get as many bugs if they're stuck in a pen and can't roam around. They also can't get as much exercise. More leg problems. And they're happier being able to move around, so we day-range them now, with a shelter and a larger area fenced off with poultry netting. They seem happier, and a lot cleaner, though it's hard to tell if a chicken is happy. Maybe Salatin doesn't mind penning them for the same reason he says he doesn't mind killing them. He said it's o.k. because "they don't have souls." I kill them, obviously, but am trying to find the most humane way, and not make up a bogus reason like that! I'm also interested in how to fatten a duck or goose liver without grain and maybe even without forcing. I've read that the ancient Egyptians used figs and olive oil!

  10. Hilary - I've sent the chapter pdf. I found some information about a Spanish farmer fattening goose liver without force feeding that you might find interesting:

    From the Sunday Times – “French are in a flap as Spanish force the issue over foie gras”

    From BBC News - The Holy Grail of foie gras?

    Pateria de Sousa -

    Thanks for sharing your experience with the mobile chicken enclosures. Interesting.


  11. So interesting about grass. Nice job Pete. I found this very interesting information.
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