Written by collaboratively by Rhea Lawrence and Jill Anderson.
The increasing demand for alternative feedstocks for biofuel production has sparked interest in South Dakota for the Brassica crops B. carinata and Camelina sativa. Carinata and camelina belong to the same plant family as canola, however they have some different agronomic attributes and oil composition. These novel oilseeds are being introduced as rotational crops in South Dakota, North Dakota, Minnesota, Montana, and in Florida as potential winter crops. Agronomic studies are currently underway to determine the benefits from growing carinata and camelina for biofuel production. However, our focus for cattle research is the byproduct after oil extraction, a meal which contains 30-40% CP. These new oilseed meals could be used as a protein supplement in livestock diets, although currently there is very limited research. A recent study by the SDSU Dairy Science department addressed their degradability and digestibility by dairy cattle. Understanding how camelina and carinata meals are utilized is important information to be able to more effectively design future projects, use them in dairy cattle rations, and determine what common feedstuffs they could compete with or substitute.
In situ measurements on rumen degradation of feeds were done using three multiparous, ruminally-cannulated Holstein cows (Figure 1). Six feeds were evaluated: camelina meal, carinata meal, canola meal, linseed meal, distillers dried grains with solubles (DDGS), and soybean meal. Replicate five gram samples were weighed into small nylon bags and ruminally incubated for 0, 2, 4, 8, 12, 24 and 48 hours. Residues from the 12 hour incubation were then used in an in vitro bench top procedure to determine intestinal protein digestibility. (Figure 2). All feeds and residues were analyzed for nutrient composition following the in situ and in vitro procedures.
|Fig. 1. Rhea Lawrence inserting bags in the rumen at specified incubation time.||Fig. 2. In vitro Daisy II Batch Incubator.|
Nutrient composition of the camelina and carinata meals compared with the other feeds tested are shown in Table 1. All test feeds contained large amounts of crude protein. Camelina and carinata meals had low fiber concentration. Ether extract (fat content) of the meals is dependent on the extraction process, namely solvent extracted or cold pressed. One concern is that carinata and camelina meals both contain anti-nutritional compounds called glucosinolates. Both meals have different glucosinolate composition (data not shown) and the full effects of how different types of these compounds affect animals are not well understood. As a result of these anti-nutritional compounds, the FDA recommends that these meals should not exceed 10% of cattle diets.
Table 1. Nutrient composition of test feeds used in the study.
|Item1||Camelina Meal2||Carinata Meal2||Canola Meal||DDGS||Linseed Meal||Soybean Meal|
|Dry Matter, %||87.6||88.5||89.2||87.3||89.0||89.8|
|Neutral Detergent Fiber||25.7||23.7||28.0||24.3||27.1||9.0|
|Acid Detergent Fiber||16.6||16.3||20.9||12.6||18.4||6.0|
|1 Expressed in % DM unless otherwise noted.
2 Camelina meal was cold pressed, Carinata meal was solvent extracted.
3 Non-fibrous carbohydrate= 100-(%NDF + % CP + %EE + % Ash).
Results of the rumen degradability and intestinal digestibility research are presented in Table 2. The proportion of ruminally degradable dry matter were greatest in camelina, carinata, and soybean meals. Ruminally degradable protein was greatest for camelina and carinata meals, on the other hand, they contained the least ruminally undegradable protein of all feeds tested. Intestinally digestible protein was less in camelina and carinata meals compared to soybean and linseed meals, but still greater than canola meal and DDGS. Camelina and carinata meals had the least intestinally absorbable digestible protein compared to the other feeds, but this was because so much of the protein was already degraded in the rumen. The amount of total digestible protein was similar in camelina and carinata meals compared to soybean and linseed meals, but greater than canola meal and DDGS.
Table 2. Rumen degradability and Intestinal digestibility results.
|Item||Camelina Meal||Carinata Meal||Canola Meal||Linseed Meal||DDGS||Soybean Meal||SEM|
Dry Matter (% of DM)
Protein (% of CP)
|Rumen Undegradable Protein (% of CP)||23.6e||29.4d||48.0b||38.8c||55.9a||41.6c||0.95|
Protein (% of RUP)
Protein (% of CP)
Protein (% of CP)
|abcde Values with unlike superscripts differ by P < 0.05 with Tukey’s test for means comparison.|
Results indicated that camelina and carinata meals are highly degradable in the rumen and are comparable protein sources. The total digestibility of this protein is comparable to soybean and linseed meals. If research can find ways to decrease or negate the potential deleterious effects of glucosinolates, these meals will be highly valuable protein sources for dairy cattle or other livestock. Because of the high protein content in these meals, even limiting dietary inclusion to 10%, they could be used to provide a large portion of dietary protein required. Based on these initial results, camelina and carinata meals show great potential as feeds for dairy cattle and more in depth animal feeding studies are needed.
This research was funded by the South Dakota State University Agricultural Experiment Station. Dr. Mark Berhow of the USDA ARS NCAUR, Peoria, IL is acknowledged for his assistance with glucosinolate analysis.