Soil-Plant Relationships


Many livestock producers are using high-intensity livestock grazing to improve soils and plants in pasture. Andrea Clemensen has investigated how grazing and fertilization affects soil organic matter, nutrients, and microorganisms. Along with that, she also looked at amounts of nutrients and secondary compounds in alfalfa, birdsfoot trefoil, reed canarygrass, and endophyte-infected tall fescue.

Alfalfa contains saponins and birdsfoot trefoil contains tannins. Both plants fix nitrogen
improving pasture growth and the crude protein content of forage. Endophyte-infected tall fescue produces two types of alkaloids, those associated with the plant and those from a fungus that lives in the grass. Reed canarygrass contains eight alkaloids.These secondary compounds benefit the plant by reducing the need for pesticides and herbicides.

From 2009 to 2011, Andrea also examined how cattle grazing at high stock densities or hay production (no grazing) affects soils and plants growing in mixtures or monocultures. Trefoil samples were analyzed for condensed tannins, fescue samples anaylyzed for the alkaloid ergovaline, reed canarygrass samples for the alkaloid gramine, and alfalfa for saponins.

Finally, Andrea investigated how plants respond to nutrient inputs from animal impact by
applying commercial fertilizer, green manure and fecal manure to each of these forage species growing in monoculture.

Concentrations of secondary compounds varied during the growing season. Saponins in alfalfa ranged between 0.8% and 5%. Tannins in birdsfoot trefoil ranged between 0.8% and 8%. Saponins and tannins were lowest in May and highest in July. Alkaloids (ergovaline) in tall fescue ranged between 60 to 350 ppb with the lowest concentrations in May and the highest in August.

Concentrations of saponins or tannins in the legumes did not change when grown next to tall fescue. However, tall fescue growing near legumes had much higher concentrations of
ergovaline and crude protein than tall fescue growing in a monoculture.

Taking ‘Behave’ to the Classroom

By Jamie Keyes


Students listen as Beth talks about cattle learning to eat sagebrush.

Agricultural students gained more knowledge about rangeland nutrition this week after a two day presentation by Beth Burritt. The sustainable agricultural production systems’ class learned about the Behave principles and application techniques. Interested students asked multiple questions about winter feeding, biodiversity and the economics of it all.

“Beth is doing something very unique that a lot of ranchers don’t know about,” said Lyle McNeal, the USU class professor.

Calee Lott, a senior in the Plant, Soils and Climate Department, found the Behave doctrine very beneficial. She wished they had more time to learn about it.

“I want to be a range manager, so this is right up my alley,” Lott said.

McNeal invites Burritt to present every year.

“A lot of my students come from ranching families. This way they can get exposure, because it is a sustainable practice,” McNeal said.

To find out more information about the Behave principles, please visit our website!

Cattle soaking up the sun or finding the shade: The difference coat color makes

Cows in the shadeOn a warm sunny day, don’t you prefer to stand in the shade? Well, surprisingly some cattle don’t.

Apparently, whether or not a cow seeks out shade depends on its coat color. Four breeds of cattle, with four different coat colors were tested to see where they spent their time in the sun or the shade.

The percentage of time each breed spent in shade (standing and lying down) was: 89% for Angus (black), 81% for MARC III (dark-red), 57% for MARC I (tan), and 55% for Charolais (white). There was a direct correlation (R2 = 0.90) between absorption of solar load, by hair coat color and percent of time the heifers spent in shade. Providing shade alleviated heat stress by lowering body temperature, especially for black and dark-red colored cattle.

Reference: Gebremedhin, K.G. et al. 2011. Body temperature and behavioral activities of four breeds of heifers in shade and full sun. Applied Engineering in Agriculture 27: 999-1006.

Photo: Claudio.Ar / Foter / CC BY-NC-SA

Self-Medication on the Range

Self medication on the RangeAnimals adapt to changes in their environment and bodies not only through physiology changes that correct for deviation from homeostasis, but also by engaging in certain behaviors. Thus, a behavior like selecting a food containing a needed nutrient is no different than the secretion of insulin from the pancreas in response to rising blood sugar levels: both responses restore homeostasis. Behavioral homeostasis has been shown experimentally. Livestock modify their intake and diet selection to rectify nutritional imbalances. Besides balancing nutrient intake, herbivores are faced with other challenges such as disease. If behavioral homeostasis exists, then sick animals should self-medicate with substances that restore their health, even substances that contain no nutrients or could be potentially toxic at high levels like plant secondary compounds.

Parasitism is one of the greatest disease problems in grazing livestock. Controlling parasites with drugs is challenging, particularly in recent times due to the rise in drug-resistant internal parasites. Evidence suggests that parasitized apes use natural plant secondary compounds (PSC) as anti-parasitic agents. Can parasitized domestic sheep and goats also learn to use PSC? If the answer is yes, they could learn to self-medicate with PSCs and eat PSC-rich vegetation, either on rangeland or pasture, when needed, while having other nutritious and safe forages available to meet their nutritional requirements.

In a controlled experiment, lambs with parasites ate more of a supplement containing tannins than non-parasitized animals, even when the supplement was very low nutrients. In contrast, lambs without parasites ate more of the supplement without tannins than parasitized lambs.

In another study, lambs with and without parasites were given a choice of alfalfa and alfalfa mixed with 10% tannin. Lambs with parasites had a greater preference for alfalfa with tannins than lambs without parasites. These differences in preference did not exist before lambs with parasites experienced the positive effects of tannins or later after parasites were killed with drugs.

Collectively, the information above suggests herbivores are “aware” of the presence of parasites infecting their bodies. If herbivores are able to sense their parasitic burdens and if there are anti-parasitic substances in plants, which can potentially provide relief, then parasitized animals should increase their preference for such plants relative to healthy animals.

Besides being aware of their parasitic burdens, a second step of self-medication is that after eating or using a certain medicinal plant, herbivores should experience relief from the upset or discomfort caused by the parasites. Animals are more likely to learn about the benefits of a medicine when they experience illness or discomfort and then eat a medicine or plant that leads to recovery.

How is self-medication knowledge acquired? Individual foraging behaviors are mainly acquired by learning from social models, first from mother, then from peers, and from individual post-ingestive experiences. The spread of the self-medicative behavior within a group seems to be influenced by social models.

Juan J. Villalba and Serge Y. Landau. 2012. Host behavior, environment and ability to self-medicate. Small Ruminant Research 103:50-59
Photo: john shortland / Foter / CC BY

Eating to Protect the Rumen

Mixing quebracho tannins into feed rations has been proposed as a means to protect dietary protein from degradation in the rumen. Unfortunately, mixing tannins into a basal ration, even at low levels, may negatively affect some individuals. Supplementing tannins may be a better solution than mixing them in a basal ration. The objective of this study was to determine if voluntary intake of tannins by sheep would enhance nitrogen use.

Table 1
Experiment 1 is outlined in the table above. The high-protein (HP) basal diet was 22% crude protein (CP) with 17% rumen-degradable protein (RDP). The low-protein basal diet (LP) was 11% CP with 8% RDP.

Sheep fed the HP basal diet ate more than sheep fed LP basal diet in Period 1, but not Period 2. Sheep fed the HP basal diet and WB with tannin had lower amounts of blood urea nitrogen and rumen ammonia nitrogen than lambs fed the HP diet and plain WB.

A new group of sheep were used in Experiment 2. The design is outlined in table two. The HP basal diet was 19% CP and 16% RDP. The LP basal diet was 12% CP and 8% RDP. The supplement base in Exp. 2 was oat straw, which is much lower in CP and digestibility than the WB used in Exp. 1.Table 2a





Sheep fed HP and OS (oat straw) with tannin ate the greatest amount of the basal diet. They also had lower BUN concentrations than sheep eating HP basal diet and OS without tannin.

However, intake of OS with tannin was higher for sheep fed the LP than sheep fed HP basal diets. When given a choice, preference for the tannin-containing food tended to be greater for sheep fed HP than those fed LP.

Tannin supplements have the potential to reduce rumen ammonia nitrogen and blood urea nitrogen in sheep, even after eating high-N diets and offered low-quality supplements.

Fernández, H.T., F. Catanesea, G. Puthoda, R.A. Distel, and J.J. Villalba. 2012. Depression of rumen ammonia and blood urea by quebracho tannin-containing supplements fed after high-nitrogen diets with no evidence of self-regulation of tannin intake by sheep. Small Ruminant Research 105:126–134.

Barnyard animal furthers cure research for Huntington’s disease

By Jamie Keyes

Smart sheepSheep have a bad reputation for not being the smartest animals in the barnyard, but research has shown that reputation may be false.

In the past, monkeys and rodents have been the experimental animal of choice for cognitive function research, but why not sheep? In 2010, the Department of Pharmacology at the University of Cambridge, decided to experiment with sheep. According to their research article Executive Decision-Making in the Domestic Sheep, sheep have a good memory and, not surprisingly, have never been used to research the cognitive functioning system. Sheep are also less temperamental than monkeys. Trials using sheep can be conducted more quickly (three weeks versus several months) than those using monkeys.

In a 21 day study, sheep were placed in a pen with two passage ways. At the end of each passage was a correct or incorrect choice, a bucket full of pellets or an empty bucket. As the experiment went on, the choices become progressively more difficult. Changing color of the buckets, different shaped objects in the way and switching the correct passageways challenged sheep to make the right decision that led them to pellets.

Even with all the obstacles, the study discovered the sheep were able to learn the difference between correct and incorrect choices. They were able to discriminate between passages, and showed irritability if a wrong decision was made.

The study concluded that “sheep have great potential, not only for use as a large animal model of HD (Huntington’s disease), but also for studying cognitive function and the evolution of complex behaviors in normal animals.”

Alzheimer’s and Huntington’s disease are known for disrupting the cognitive functioning system. Now, through research, sheep can contribute a way to the cure.

Morton AJ, Avanzo L (2011) Executive Decision-Making in the Domestic Sheep. PLoS ONE 6(1): e15752. doi:10.1371/journal.pone.0015752

Photo: Bob Jagendorf / Foter / CC BY-NC

Digestion Trials with Fresh Forage

alfalfaBased on our previous experiments, Jake Owens designed a digestibility study to investigate how eating alfalfa or birdsfoot trefoil (BFT) before eating endophyte-infected tall fescue (TF) or reed canarygrass (RCG) might benefit livestock compared to livestock eating only tall fescue or RCG alone.

Trial 1: Lambs were offered alfalfa for 30 min then offered either TF or RCG for 3.5 h. In this study, fresh forage was cut and offered to each animal. Lambs ate more food, nitrogen, and energy when they ate alfalfa before eating TF or RCG compared to lambs fed only tall fescue or RCG. But eating alfalfa reduced the amount of TF and RCG compared to animals that did not receive any alfalfa.

Trial 2: Trial 2 used a new group of lambs and was similar to Trial 1 except lambs were fed BFT prior to receiving TF or RGC. Lambs fed BFT ate slightly less RCG, but much more TF than animals that did not receive BFT.

Overall, lambs ate less BFT than alfalfa, but lambs that ate BFT ate much more TF than lambs fed alfalfa. In both studies, feeding two forages had no affect on the digestibility of any of the forages.

The enhanced intake of TF by lambs fed BFT, as well as the greater nutrient intake by lambs fed a legume and a grass is likely due in part to complementary profiles of alkaloids, saponins, and tannins.

Owens, J., F.D. Provenza, R.D. Wiedmeier, and J.J. Villalba. 2012. Supplementing endophyte-infected tall fescue or reed canarygrass with alfalfa or birdsfoot trefoil increases forage intake and digestibility by sheep. J. Sci. Food Agric. 92:987-992.

Photo:  International Livestock Research Institute / Foter / CC BY-NC-SA

A Change in Foraging Behavior

All plants contain secondary metabolites (PSMs). These compounds can be toxic at high doses or can act like medicines at low doses. PSMs often provide benefits to plants such as increased pest resistance, drought tolerance or competitive ability. Unfortunately, many of these compounds are toxic to animals (from insects to mammals) and reduce intake of plants.

The objective of this study was to determine how different PSMs might affect the diet selection of sheep grazing forages with different PSMs: 1) alfalfa (saponins), birdsfoot trefoil (tannins) and tall fescue (alkaloids).

ChangingforagebehaviorAfter the early morning dosing with tannins, saponins or an alkaloid (ergotamine) lambs were allowed to graze a pasture that contained birdsfoot trefoil, alfalfa, endophyte-infected tall fescue, and orchard grass.

Trial 1: Lambs gavaged with tannins spent more time grazing birdsfoot trefoil and tall fescue.

Trial 2: Lambs gavaged with saponons spent more time grazing tall fescue and the least time grazing alfalfa.

Trial 3: Lambs gavaged with ergotamie (alkaloid) spent more time grazing birdsfoot trefoil and the least time grazing tall fescue.

Lambs minimized the negative impacts of PSC by changing their foraging behavior to avoid over-ingesting any one PSC and by selectively increasing their preference for forages containing other PSMs.

Reference: Villalba, J.J., F.D. Provenza, A.K. Clemensen, R. Larsen, and J. Juhnke. 2011. Preference for diverse pastures by sheep in response to intraruminal administrations of tannins, saponins, and alkaloids. Grass Forage Sci. 66: 224–236.

What Affects Meat Quality and Flavor?

SteakGrass-fed livestock may provide health benefits of milk and meat from grass-fed ruminants, but little is known about how PSCs (plant secondary compounds) in various forages affect the color, flavor, and health properties of meat. Recent evidence suggests PSCs can positively influence the flavor, color and health properties of their meat and milk. For instance, tannins positively influence meat color and quality, as well as milk yield and protein content, and they markedly improve meat fatty acid composition, a major concern for consumer health. Saponins have both anticancer and immunomodulatory properties as well as cholesterol-lowering activity and saponins in the diet can be traced in the meat.

Diet also affects the palatability of meat and “off-flavors” are due in part to fatty acids in the
meat of cattle fed forages. Herbage quality, fatty acid composition, rates of microbial
fermentation in the rumen, microbial hydrogenation of double bonds, and rates of passage
through the rumen all affect flavors of meat from cattle finished on pasture (Waldman et al.
1968). Interestingly, supplementing lambs with tannins reduces the concentration of skatole (3- methyl-indole) in their back fat, which diminishes the unpleasant “sheep” and “off-flavors” flavor in meat (Priolo et al. 2009).

Taste panel results from our studies show high liking for beef samples obtained in both groups of cattle (fescue/alfalfa and fescue/sainfoin). From 25% to 45% of consumers liked the beef moderately, 35% to 25% liked the samples very much and 2.5% to 15% liked the beef extremely well. The effects of secondary compounds (tannins and saponins) in reducing the population of bacteria that produce off-flavors like skatole may explain these high scores given by consumers to grass-fed beef, when scores for standard grass-fed beef are generally lower. Polyunsaturated fatty acids (C 18:3 n 3) were also higher in animals grazing sainfoin than in animals grazing alfalfa, presumably due to the effects of tannins on ruminal biohydrogenation. These results suggest animals are able to mix forages of different qualities — fescue, sainfoin, alfalfa — in ways that produce tastier and healthier meat.

Add-On: Learning in Utero…and Early in Life

Baby lambThe crucial role of the peri-weaning period in the development of lamb feeding preferences was examined in the present study.

Without their mothers present, lambs were fed a commercial diet flavored with oregano essential oil between the 15th and 55th day of their life. After the 55th day, animals were fed the same commercial diet, but without oregano oil.

At the age of 3, 5, 7, 9 and 11 months of age, preferences of lambs were tested by offering them 4 different test feeds with added eucalyptus or mint or orange or oregano essential oil. Previous exposure to oregano flavor influenced the acceptance of oregano-supplemented feed later in life, especially after the age of 9 mo.

Simitzis, P.E., J.A. Bizelis, S.G. Deligeorgis, and K. Fegeros. 2008. Effect of early dietary experiences on the development of feeding preferences in semi-intensive sheep farming systems – a brief note. Appl. Anim. Behav. Sci. 111:391–395.

Photo:  Sarah Elizabeth Altendorf / Foter / CC BY-NC