Texas A&M AgriLife Research Wood to Feed Program

Wood to Feed Program






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Rising feed costs and drought have been two of the most important factors responsible for reducing livestock inventories. Brush (e.g. blueberry juniper, redberry juniper, and mesquite) encroachment exacerbates these problems by decreasing forage production and surface water infiltration. Drought cannot be controlled, but a livestock production practice does exist that can help increase U.S. livestock inventories, while at the same time, reduce brush encroachment and wildfires, increase natural resources, and enhance rural economies:  Processing trees into a livestock feed ingredient (Fig. 1). feedstuffs

Is ground wood really a roughage source?
Research dating back to the early 1900’s, along with current TX A&M AgriLife Wood to Feed (San Angelo) trials, have shown that ground woody products can be used as roughage ingredients in livestock diets. Our trials have shown that these ingredients have nutritional and feeding values similar to some traditional roughages, can reduce internal parasite infection, and do not negatively affect the fetus, end-product quality, or sensory characteristics of the cooked meat. In fact, using ground juniper in lamb feedlot diets has actually enhanced tenderness and juiciness of cooked chops without negatively affecting off-flavor.


Is removing and processing trees economically feasible and sustainable?
Commercial brush harvesters are predicting that they can profitably sell a hammermilled woody product for under $100/dry ton. Some scenarios where a commercial operator blows chips directly into a rancher’s trailer, predict that a final hammermilled product will cost less than $50/dry ton. Thus, a solid foundation has been created to safely, effectively, and profitably use ground woody material as a roughage ingredient on a commercial scale. Commercial tree harvesting and processing industries already exist. Thus, after ground juniper gets approved by FDA as a commercial feed ingredient, I predict that a commercialized industry will be developed and that woody feed ingredients will become available; if so, potential impacts are enormous.

Consider a scenario where only one beef cattle feedlot (60-thousand head) begins using only 10% ground woody in total mixed rations. This feedlot would need approximately 17,520 tons (DM basis) of ground wood/yr. If the roughage they are currently using costs $170/ton and juniper is purchased for $140/ton, then this feedlot would save approximately $526,000/yr in feed costs; assuming that total feedyard costs (cost/kg of gain, days on feed, etc.) are similar. In addition, there is high probability that selling a ground wood ingredient at $140/ton would result in, at the very least, a $10/net profit to the seller, resulting in a total net profit of $175,200/yr.

To supply this 60,000-head feedlot with 17,520 tons (DM basis) of ground juniper/year, 140,000 trees would need to be harvested from approximately 2,333 acres each year (assume 250 lbs. of DM/tree and 60 trees/acre). The previously mentioned $10 net profit/ton of woody product sold does not include charging for brush removal; thus, 2,333 acres would be harvested at no cost to the landowner.

There are approximately 2.4 million head of cattle on feed in Texas. If ground woody products begin to be utilized like other traditional roughages, and if all of these cattle were fed diets with only 10% ground wood, then 730,000 tons of ground wood would be needed/year, resulting in 5.84 million trees harvested/yr, resulting in the free removal of brush from 100,000 acres of rangelands each year. Reducing woody brush cover has been shown to increase forage production, which would further reduce livestock production costs.

Considering that numerous other national and international markets exist for multiple classes of ruminant animals (e.g., dairy cattle, sheep and goats, wildlife), the potential for an economically sustainable Wood to Feed Industry, which synergistically enhances natural resources, is enormous.



Research trials dating back to the early 1900’s have shown that ground woody products can successfully be used as a roughage ingredient in livestock diets. Maynard (1920; Cornell Univ. Experiment Station) published a review related to the use of feed in Germany during wartime. In this review, the author discusses that “unconsidered or unused” feeds were found to be useful. Other notable comments include: 1) “According to experiments… cellulose from pine wood was found digestible in large measure and its use in quantities up to two and a quarter pounds per horse/day, together with 6 pounds of oats and 3 to 6 pounds of hay was advocated” and 2) “… it must be noted that the unusual materials employed were resorted to by necessity and not from any belief that they were superior to, or even as satisfactory as the rations normally used.”

During the 1920’s, the WI Agricultural Experiment Station, USDA Forest Product’s Laboratory (Madison, WI), USDA experiment station (Beltsville, MD), USDA Bureau of Animal Industry, and the MA Agricultural Experiment Station (Amherst, MA) began evaluating the use of raw and pre-treated ground wood material as a feed ingredient (Sherrard and Blanco, 1921; Morrison et al., 1922; Archibald, 1926). These initial trials evaluated various feeding programs to establish nutritive values for various types of sawdust. Authors evaluated performance and health of sheep and cattle, and milk production from dairy cattle. Research using ground wood declined during the 1930s, but the number of studies that evaluated the use of foliage (leaves and small twigs) increased; this is especially true in the Soviet Union where they termed the foliage material, “Muka” (NRC, 1983). In addition, between 1920 to 1960, numerous trials evaluated the use of chemically pre-treated wood as livestock feed (reviewed by Ellis, 1969 pdf).

During the 1950’s, interest in utilizing the entire tree as livestock feed was once again raised after the Texas Agricultural Experiment Station (now TX A&M AgriLife Research) reported that ground mesquite wood could be successfully used in cattle diets (Marion et al., 1957) reported that calves fed a diet of 52% ground mesquite (mixed with concentrates) consumed approximately 2.57 kg of mesquite/d (12.6 g/kg of BW) without any negative health effects. Table 1 shows that the ground mesquite had greater CP and similar total fiber vs. CSH. During Trial 1, steers were fed a diet with up to 46% mesquite, resulting in a maximum daily mesquite intake of 4.28 kg (14.6 g/kg of BW); no negative health effects were observed. During Trial 2, steers were fed a diet with up to 50.6% mesquite, resulting in a maximum daily mesquite intake of 6.85 kg (17.3 g/kg of BW); no negative health effects. In conclusion, these authors stated “No ill effects resulted from feeding the ground wood.”

Table 1. Chemical composition (DM basis) of ground mesquite wood and cottonseed hulls, Marion, 1957 (pdf)

Feed CP, % Fat, % NFE1, % Fiber, % Ash, % P, % Carotene, ppm
Ground mesquite wood 6.3 0.8 37.5 51.5 3.8 0.06 26
Cottonseed hulls 4.5 1.0 52.5 52.5 3 0.03 0

1NFE = nitrogen-free extract = 100 – (CP, fat, water, ash, and fiber).

During the late 1960’s and throughout the 1970’s and 1980’s, Texas Tech University evaluated the use of non-treated and pre-treated ground mesquite trees in steer and cow diets (Ellis, 1969 pdfParker, 1982 pdf). Ellis (1969) reported in a preliminary trial (no control group) that ground 6-yr old mesquite trees (with leaves) were processed, mixed with other ingredients and fed to cows. Maximum consumption of ground mesquite was 7.26 kg/day. Results suggested that the cows “were not on a high enough nutritional plane to support milk production.” Authors report negative health in some of the cows, but state that they do not know if these effects were due to the diet and make statements such as: “the death did not appear to be related to the ration” or “such weight loss is recognized as normal for cows being wintered on the range.” Authors also report that “data indicated that the ration containing mesquite was reasonably adequate for maintenance. The sharp weight loss post parturition suggests that the wood was inadequate as a major component of the ration for suckling cows.”

Ground wood from various Populus tree species (e.g., quaking aspen) was thoroughly evaluated during the 1970’s by researchers from various institutions, e.g. Penn State, University of WI (Dairy Sci. Dept.; Madison, WI), Forest Products Lab (Madison, WI), SD State University (Brookings), and the University of Alberta. These research efforts led to the approval of ground aspen as a feed ingredient by AAFCO in 1980 (AAFCO, 2011). At one time, ground aspen feed was commercially available from a wood processing mill. Currently, ground aspen bark is being used and sold commercially (3XM Grinding and Composting, Olathe, COLohmeyer, 2013) and ground aspen wood is being sold in mixed feeds (Land O’Lakes Purina Feed®, e.g., Mazuri Browser Breeder).

The Billings Gazette (Unknown, 1975 pdf) reported that the SD Department of Game, Fish, and Parks and SD State University collaborated and successfully (no reports of negative health issues) fed steers a diet consisting of 45% ground aspen. Results indicated that “aspen-fed cattle gained weight about twice as fast as the alfalfa-fed group” and that cattle on a pervious trial were “tasty and tender.” Satter et al. (1970) fed lactating cows a mixed diet containing 32% aspen and reported: 1) aspen sawdust (consumed up to 4.8 kg/day or 7.6 g/kg of BW) was effective as a partial roughage substitute in a high-grain dairy ration; 2) if less dietary aspen would be equally as effective in complete pelleted dairy rations, aspen sawdust could become an attractive roughage substitute in areas where hay is expensive and difficult to obtain; and 3) no adverse effects on animal health. Satter et al. (1973) reported that a mixed diet containing 30% aspen sawdust did not negatively affect DMI or milk parameters in dairy cattle and concluded that it was “as effective as 50% long hay to maintain normal luminal [ruminal] acetate-to-propionate ratios.” In this trial, cows consumed up to 5.32 kg of aspen/day (8.38 g/kg of BW).

Research by Satter et al. (1970, 1973) was reinforced by Schingoethe et al. (1981) who reported that 30% aspen pellets (made from whole aspen trees) in a mixed diet, could be safely fed to lactating dairy cows. These cows safely (no adverse effects on animal health) consumed approximately 5.82 kg of aspen/day (9.77 g/kg of BW) and the authors reported that the aspen diet vs. control diet, increased ruminal pH and did not affect milk production. Authors also state that “the amount of fiber in the aspen ration may limit feed intake due to gut fill during peak of lactation. For this reason feeding more than 30% of the total ration DM as aspen would not be recommended, and even 30% … might be too high for cows in early lactation.” Dr. Whitney’s comment: This statement does not seem warranted, considering that total DMI and milk production were similar for cows fed diets with or without (control) aspen wood.

Mathison et al. (1986) fed sheep and cattle diet containing 42% ground aspen and 58% hay. Apparent digestibility of the aspen in the diet was approximately 25 to 37% and the cattle consumed approximately 2.52 kg of aspen/day (6.3 g/kg of BW). Authors report that the cattle consumed a total of 6 kg of the hay and aspen mixture/d, which was “77% of the intake … when only hay was fed; sheep ate “61% as much of the aspen-hay mixture” vs. hay alone. No adverse effects on animal health were reported and the authors concluded, “… the feeding value of unprocessed aspen in ruminant diets is less than 75% of the feeding value of straw.”


Very little research related to the use of woody products as animal feed ingredients was done between 1980 and 2007. However, in 2008, we (Texas A&M AgriLife Research, San Angelo) evaluated effects of replacing CSH with air-dried redberry juniper leaves in Rambouillet lamb feedlot diets (Whitney and Muir, 2010). In this trial, a maximum of 30% juniper leaves was included in a mixed diet that fed for 28 days; lambs were transitioned onto a mixed diet containing 15% juniper for an additional 49 days. Maximum daily juniper leaf consumption was 357 g (11.9 g of juniper/kg of BW). No negative effects on animal health were reported based upon visual assessment, but replacing 50% of the CSH with redberry juniper leaves increased lamb growth performance, compared to diets containing CSH or juniper as the sole roughage source. We concluded, “Results indicate that air-dried redberry juniper leaves can effectively be used as a roughage source and can replace all of the CSH in lamb feedlot rations, but may reduce intake and consecutively growth at greater inclusion levels. We also suggested that secondary compounds and their interactions with nutrients should be considered when evaluating the nutrient requirements of the animal and its rumen microbial populations. Utilization of juniper as a roughage source could provide ranchers with a readily available on-site feed resource and possibly lessen the negative impact of this undesirable invasive brush species…”

Results from Whitney and Muir (2010) led to a trial in which mixed diets containing ground juniper leaves and small stems were fed to lambs (Whitney et al., 2014). Whitney et al. (2014) evaluated effects of using ground redberry juniper (leaves and stems < 2” diameter) in Rambouillet wether lamb (n = 45) feedlot diets on growth, blood serum, fecal, and wool characteristics. In a randomized design study with 2 feeding periods (Period 1 = 64% concentrate diet, 35 days; Period 2 = 85% concentrate diet, 56 days), lambs were individually pen-fed isonitrogenous corn DDGS-based diets where 0% (0JUN), 33% (33JUN), 66% (66JUN), or 100% (100JUN) of the oat hay was replaced by juniper. During Period 1, lambs consumed approximately 367 g of juniper/day (12.2 g/kg of BW). During Period 2, lambs consumed approximately 207 g of juniper/d (4.73 g/kg of BW). Serum urea N (SUN; 18 to 31 mg/dL) increased quadratically (P = 0.01) and fecal N increased linearly (P = 0.004), which was partially be attributed to greater dietary urea and CT intake. Most wool characteristics were not affected, but wool growth/kg of BW decreased quadratically (P = 0.04) as percentage of juniper increased in the diet. Overall, results indicated that replacing all of the ground oat hay with ground juniper in lamb growing and finishing diets is not detrimental to animal performance or health. We concluded: “… Results indicate that ground juniper leaves and stems can effectively replace all of the oat hay in corn DDGS-based growing and finishing diets without negatively affecting animal health, performance, or wool characteristics. However, using a combination of juniper and oat hay during the growing period (Period 1; high roughage diet) increased growth performance and reduced total feedlot costs as compared to using juniper or oat hay as the sole roughage source.”

Two additional feedlot trials, funded by the National Sheep Industry Improvement Center (NSIIC) were recently completed (Summer of 2014). We evaluated the effects of using 4 species (redberry, blueberry, one-seed, and eastern red cedar) of mature juniper trees and 1 mesquite specie as the sole roughage source in Rambouillet lambs (Trial 1) and Boer X Spanish cross goats (Trial 2) feedlot diets on growth performance, and wool, carcass, and sensory characteristics. We are currently analyzing the data and will publish the results during 2015.

In conclusion, trials conducted over the past 100 yr that have evaluated the use of tree fodder (leaves and small pliable twigs) and ground wood, along with numerous research summaries, suggest that various tree species can be processed and safely used in ruminant animal diets. Any negative effects of using ground wood generally involve reduced DMI, thus reduced growth performance. A few cases of impaction have been documented; however, other ground roughages can also cause compaction and thus, ground wood does not pose any extraordinary health issues. Furthermore, many approved woody and non-woody plants that are currently used as feed ingredients contain the same secondary compounds as ground juniper (e.g. volatile oil and CT in ground aspen and CT in sorghum grain, CSH, and sericea lespedeza hay, etc.). Even though secondary compound intake was not directly evaluated in many of the documented studies that evaluated animals that were fed mixed diets, no negative health effects, other than those related to physical form of the ingredient, were noted.

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