Final report for OS22-154
Project Information
Year-round grazing is feasible in Alabama and Southern USA through the utilization of cool- and warm-season forages. This can be achieved by allowing for as much grazing as possible throughout the year. Producers should select a combination of forages with different growth cycles that will best support the objectives of their operation. Besides economic benefits, year-round pastures offer better environmental quality compared to seasonal pastures. The development of sustainable year-round pastures requires the incorporation of different types of annual and perennial grasses and legumes into the existing pastures.
A series of experiments were conducted at the George Washington Carver Agricultural Experiment Station in Tuskegee University to develop and demonstrate a profitable and sustainable year-round forage-based production system with sunn hemp forage, soybean (Glycine max) or bermudagrass system in the summer-fall period, and annual ryegrass or ryegrass + legume (Australian pea, berseem clover, and hairy vetch pastures in the winter for goat production for the Southeastern U.S. during the last 2-3 years. Our results indicated that animals on sunn hemp (as a summer forage) or ryegrass + berseem clover combination (as a winter forage) grew 18-44% faster and reached the expected slaughter weight in less time when compared to bermudagrass or ryegrass pasture systems, respectively. The sunn hemp in the summer and fall and the RG+ BC for winter and spring grazing systems were the most productive with regards to biomass and average daily gain (ADG) production. This is probably due to higher nutritive values of forage diets throughout the year and different rumen microbial fermentation rates (Min, 2018; Min et al., 2019). For summer pasture, SH had greater dry matter production (4,200, 3,144, and 1,689 kg DM/ha), higher nutritive value, and better average daily gain than the pasture soybean and BG pasture in meat goats (Min, 2018). Sunn hemp contained higher crude protein (23.9, 16.3, and 7.3%) and lower fiber composition (as measured by neutral-detergent fiber; 56.1, 43.4, and 71.0 %) than forage soybean and Bermuda grass forages, respectively at the beginning, at the midpoint and at the end of the grazing season. Average daily gain (ADG) was highest (129.2 g/d) for goats grazing on SH and was lowest (19.7 g/d) for goats on bermudagrass and middle ADG for soybean pasture (81.1 g/d), probably due to high nutritive value of bermudagrass and lower internal parasites infection (Min, 2018). We feel that using proper legume forages (ryegrass + berseem clover) for the winter grazing followed by summer forages can provide for a profitable year-round foraging system. However, a combination of forages used for grazing should be selected to optimize animal performance, enhance the soil property and reduce environmental impacts from animals while reducing dependency on petrochemical fertilizers. We are hoping that combining such as sunn hemp and multi-forages with legumes will increase protein output as well as restore N in the soil. A major benefit of the SH forage is the fact that it supplies the N, Ca, and organic matter for winter forage plots even after the grazing. When planting winter forages we may need no additional N or K throughout the winter and some nutrients may be available for the next warm season crop. This can serve as an alternative forage and complement our effort for a successful year-round grazing system.
Producers need on-farm demonstration trials to directly see this practice and compare it with other practices for sustainable beef cattle production. The economic analysis of each system will provide an insight into the understanding of which year-round grazing system, especially different genotypes of sunn hemp forage included is sustainable in Alabama and surrounding states with similar climatic conditions. Two farmer cooperators have been selected from Lee County and Greene County to participate in the project. Each mentor farmer will represent a treatment. This farmer will serve as model farmers to help other small farmers in the surrounding counties and across the region.
The purpose of this project is to compare the production and economic performance of different grazing systems by Alabama mentor beef producers. The specific objectives are to:
- To evaluate forage characteristics of four sunn hemp genotypes (AU Golden, Tropic Sun, Crescent Sunn, Ubon, and Blue Leaf) and stage of growth on herbage biomass production, nutritive value, and N fixation, and beef cattle performances (forage intake and average daily gain) to sunn hemp dietary inclusion;
- To determine animal health and performance of beef cattle when sunn hemp is incorporated in the feeding system and when grazing multi-culture grasses, and grasses in combination with legumes followed by winter forages;
- To identify and assess economic characteristics and optimum economic return of different beef cattle production (grasses/legumes) systems;
Two farmer cooperators, each having at least 30 animals, have agreed to participate in the project.
Objective 1: two experiments will be conducted at the Caprine Research and Education Center (Exp. 1) and two on-farms.
Exp. 1 (at TU): The treatment will be the factorial arrangement of four sunn hemp genotypes (AU Golden, Tropic Sun, Crescent Sunn, Ubon, and Blue Leaf). A split-plot design with three replications will be implemented in which three harvest regimes (35, 55, and 75 days after planting (DAP)) will be considered as the main plot and the two plant components (leaf and stem) as subplots. Forage accumulation, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), in vitro dry matter digestibility (IVDMD), in vitro ruminal gas production (ANKOM gas production system), and ruminal fermentation characteristics over DAP will be tested on plant components. The experiment will be established in plots measuring 3 by 24 m during the summers of 2022 and 2023 with new planting and randomization plan each year. A disc harrow, typical of a conventional tillage practice, will be implemented to prepare the experimental fields. In order to evaluate the adaptation of sunn hemp to local environmental conditions under low-input systems, supplemental fertilizer, irrigation, or weed control measures will not be applied in either year. A commercial legume seed inoculant (Molokai Seed Company, Hawaii, USA) that contained Bradyrhizobium sp. (Vigna) will be used to inoculate forage-type sunn hemp cultivars seeds. Seeds at the rate of 22.5 kg/ha will be drilled using a no-till drill approximately at a depth of 2.5 cm and 0.20 m row spacing.
Exp. 2 (two on-farm trials, 2022): The second treatment will be the factorial arrangement of two sunn hemp genotypes (AU Golden vs. Tropic Sun) and two-stage of days after planting (DAP; stage of growth: 55 vs. 75 DAP) in a randomized complete block design. Thirty-two growing steers (about 400-600 lbs. n = 8 per treatment; 2 replicates in each treatment) will be randomly assigned to each treatment during summer (Jun– October) and the whole herd productivity of each group will be measured. The variables measured will include body weight change, body condition score change, fecal egg counts, pasture growth, and forage chemical nutritive values changes. Visits will be made to each mentor producer to detail collaboration upon project approval. Depending on summer growing conditions, warm-season forages will be planted in April each year. Animals will be introduced 55 days after seeding or flowering (~75 DAP). Total grazing days will be calculated depending on forage availability. The interrelationship between stocking rate and grazing period or their mathematical relationships (e.g., gain/acre = ADG x days in grazing period x stocking rate) will be calculated.
Objective 2 (two on-farm trials, 2023): treatments will be 100% sum hemp, 50% sunn hemp + 50% bermudagrass, or 100% bermudagrass forage diets distributed in a completely randomized design. We plan to plant a 100% perennial bermudagrass, 100% sunn hemp, and its combinations (bermudagrass /sunn hemp in 50: 50%) with recommended seeding rate. To establish a successful stand of sunn hemp, the seed will be drilled and covered ½ to 1 inch deep, with the seeding rate of 40 to 50 pounds per acre in 6-inch rows. Animals will not be introduced until the pasture height is 6 inches tall.
Combining summer forage grazing followed by winter grazing (January-April) will also be conducted to see the minimum requirement of fertilizers for forage biomass production as well as restore N in the soil, thus reducing dependency on petroleum-based fertilizers. We plan to plant wheat and rye (WRG) grasses (late summer) with recommended seeding rate (in a mixture of 60 lbs/ac; Ball et al. 2002) on summer forage plots in bermudagrass, sunn hemp, and combinations of bermudagrass, and sunn hemp pastures, respectively. The interrelationship between forage combinations (e.g., the carry-over effect of soil N) will be conducted. Animals and all the experimental measurements will be the same as the summer forage system.
Objective 3: each producer will be trained to keep records. The records will include animal-related records, pasture records, and other input costs (e.g, veterinary items). We will provide ear tags, seeds, and veterinary items for all animals at the farms. The available forages and plant species will be sampled for lab analysis. Records will be kept on the actual amount consumed by animals along with the hay used. Prior to the introduction of animals into pastures, all the animals will be vaccinated with a modified-live virus (MLV) product in newly received beef calves to improve gain and immune response and animals will be dewormed with Cydectin (moxidectin; Fort Dodge Animal Health, Fort Dodge, IA, USA). Gastrointestinal parasitic load in beef cattle will be monitored by using fecal egg count (including coccidian) fortnightly. The blood samples will be taken before and after the experiment is completed for pack cell volume and blood chemistry. Enterprise budgets will be prepared for each individual producer. Data will be analyzed using the general linear model (GLM) procedure of SAS (SAS, 1991). Differences among means, for all analyses, will be determined by the least-square means procedure with the protected F-test (P < 0.05).
I- Summary
Warm-season perennial grasses are the most commonly used forages in the Southern United States; however, nitrogen (N) fertilization is necessary to maintain their productivity and forage quality. Warm-season forage legumes can help improve forage nutritional value and add nitrogen to the grazing soil system through biological atmospheric N2 fixation. Sunn hemp (Crotalaria juncea L.) is a fast-growing warm-season annual legume that can be adapted to tropical and subtropical regions in the world as a green manure and cover crop. However, it may be a valuable source of forage and variety of sunn hemp for livestock. At early maturity, sunn hemp has sufficient crude protein concentration levels to meet the requirements of most livestock categories. Additionally, the fixed N recirculates back to the pasture through cattle excreta or litter, becoming available for the companion grass if grown in a mixture. Year-round grazing is feasible in Alabama and the Southern United States through the utilization of cool- and warm-season forages. This can be achieved by allowing for as much grazing as possible throughout the year. Producers should select a combination of forages with different growth cycles that will best support the objectives of their operation. A series of experiments were conducted at the Caprine Research and Education Unit in George Washington Carver Agricultural Experiment Station in Tuskegee University to develop and demonstrate a profitable and sustainable year-round forage-based production system with sunn hemp incorporating different sun hemp varieties with multi-forage combinations systems in the summer-fall for beef cattle production for the Southeastern U.S. All forage legumes, including sunn hemp (Crotalaria juncea L) and red sunn hemp (Crotalaria ochroleuca), thrive during drought and on marginal soils with a pH between 5.0 and 7.5. Among the sunn hemp varieties over time, sunn hemp Thailand 2 exhibited significantly greater biomass production (113.7 vs. 92.5 to 62.5 ton/ac, respectively), plant growth rate (140.2 vs. 116.1 to 61.7 cm, respectively), and superior chemical composition such as crude protein (CP) and total digestible nutrient (TDN) compared to other sunn hemp varieties (red sunn hemp, Thailand 1 and 3) For multi-forage system with sunn hemp verieties, Mexican Teosinte (TEO; Euchlaena mexicana), sudan grass (SG) + sunn hemp (15 to 20%) combinations produce more biomass than Pearl millet + sunn hemp (5% and 15%) combinations, especially during heat or drought stress (Table 3; Fig. 4). The SG + sunn hemp combinations (15% and 20%) and TEO also provides highly digestible forages as measured by IVDMD and provided excellent nutritious forage that is readily utilized by livestock and wildlife in the summer (Table 3). These results suggest that SG + sunn hemp (15% and 20%) combinations may be more beneficial for achieving high biomass production and supplying sufficient nutrients to maintain dietary nutritive value for grazing animals. However, the SG + 5% sunn hemp combination did not impact additional biomass production, so a minimum of 15 to 20% sunn hemp is recommended for a multi-forage system to improve maximum biomass production per acre. Due to severe drought, we were unable to conduct on-farm trials on soil quality and animal performance. It appears that sunn hemp, or a combination of sunn hemp with other summer cover crops, can fit nicely into a sustainable livestock production system in the Southern United States.
Cooperators
- - Technical Advisor (Educator and Researcher)
Research
Data Collection
For this objective, six varieties of sunn hemp forage combinations were planted on 0.2 acres each at the Caprine Research and Education Unit during 2022 and 2023, and the trials have been completed. Forage biomass production (kg DM/ha; Table 1), botanical composition, and forage chemical composition (Table 2) were measured. On each occasion, four random quadrats (0.25 m²) per paddock were cut with a hand clipper for biomass sampling. The forage samples were then oven-dried at 90 °C for 18 hours and weighed. For laboratory analysis, four quadrats of herbage on offer were cut to ground level from each paddock. Samples were combined for each paddock, mixed, and divided, with the first portion used for botanical composition assessments and the second portion for chemical analysis including crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), total digestible nutrient (TDN), and in vitro rumen digestibility (IVDMD).
For objectives 1-2, six combinations of forages with different levels of sunn hemp (5%, 15%, and 20%) were planted on a 1-acre plot each during 2024 at the Caprine Research and Education Unit, Tuskegee University, AL, and have been completed. Six different forage combinations were evaluated for forage biomass production, nutrient chemical composition, and in vitro dry matter digestibility (IVDMD).
In vitro digestibility of forages
A set of in vitro experiments was conducted to determine the effect of diets on in vitro dry matter digestibility (IVDMD) when diets were incubated with mixed rumen fluid. In vitro rumen incubations, along with two blank incubations, were completed. Bottles containing only inoculum and buffer served as blanks. Each incubation was done in triplicate. The anaerobic condition was maintained by continuously flushing the bottle's headspace with CO2. For in vitro incubations, 6 g of mixed diets (% as-fed) were placed in 250 mL ANKOM (ANKOM Technology Corp. Macedon, NY) sample bottles containing 50 mL of pooled ruminal fluid (pH 6.0) and 40 mL artificial saliva (pH 6.8; Min et al., 2005). Bottles were flushed with CO2 gas before being capped with an ANKOM Gas Production module. One liter of FlexFoil PLUS sample bags (SKC Inc., Eighty-Four, PA) was connected to the modules. Bottles were placed in a shaking incubator at 39oC. Cumulative ruminal gas production was recorded every 30 minutes for 24 hours via the ANKOM system, which records pressure buildup in individual vessels. The remaining contents of the sample bottle were used to estimate the IVDMD. The bottle contents were poured into pre-weighed 250 mL beakers, dried in a forced-air oven at 60°C for approximately 48 hours, and then weighed.
Laboratory Analysis
Dairy One Forage Testing Laboratory (Ithaca, NY) analyzed ingredients' and DM's nutrient and mineral content. Analytical DM concentrations of diet samples were determined by oven-drying at 105°C for 24 hours. Ash, ether extract, and minerals were analyzed according to the methods described by AOAC (AOAC 1998). Concentrations of N were determined using an organic elemental analyzer (Flash 2000; CE Elantech Inc., Lakewood, NJ, USA; AOAC (AOSC 1998). Concentrations of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were sequentially determined using an ANKOM200/220 Fiber Analyzer (ANKOM Technology, Macedon, NY, USA) according to the company's methodology, which was based on the work of Van Soest and Roberton, (1985). Sodium sulfite was used for NDF determination and pre-treated with heat-stable amylase (Type XI-A from Bacillus subtilis; Sigma-Aldrich Corporation, St. Louis, MO, USA). Total digestible nutrient (TDN) concentrations were calculated based on % NDF content (Van Soest and Roberton, 1985).
Statistical analysis
All data were analyzed as repeated meas
Objective 1: Table 1 and Fig. 1 illustrate the effects of six different forage genotypes on forage biomass production and growth stage (in cm). All forage legumes, including sunn hemp (Crotalaria juncea L.) and red sunn hemp (Crotalaria ochroleuca), thrive during drought and on marginal soils with a pH range of 5.0 to 7.5. Over time, among the sunn hemp varieties, sunn hemp Thailand 2 exhibited significantly greater biomass production (113.7 vs. 92.5 to 62.5 ton/ac, respectively), plant growth rate (140.2 vs. 116.1 to 61.7 cm, respectively), and a superior chemical composition (CP and TDN) compared to other sunn hemp varieties (Tables 1 and 2). However, the ADF and NDF values were lower for Thailand-II sunn hemp compared to other varieties (Table 2). Mineral compositions varied among the varieties. The results demonstrate that sunn hemp is an excellent choice for a summer cover crop in the southern United States. It has a high nutrient composition (e.g., CP, TDN, etc.) and produces greater biomass per acre. Returning nitrogen to the soil suppresses weeds and nematodes, enhances soil tilth and water-holding capacity, and reduces erosion in fields lacking plant cover.
Table 1. The effect of forage genotypes and growth stage on biomass production (ton DM/ha).
|
Biomass |
Crotalaria juncea 1 (Flowering) |
Crotalaria juncea 2 (non-flowering) |
Crotalaria Thailand 1 |
Crotalaria Thailand 2 |
Crotalaria Thailand 3 |
Red sunn hemp (Crotalaria ochroleuca) |
SEM |
P-value |
|
Day 30 |
20.0b |
52.0a |
39.0b |
49.0a |
44.0b |
41.0a |
7.03 |
0.01 |
|
Day 50 |
50.0b |
67.0a |
68.0a |
74.5a |
48.5b |
35.5c |
7.04 |
0.01 |
|
Day 65 |
117.5b |
163.0b |
170.5a |
217.5a |
168.0b |
118.0b |
7.05 |
0.01 |
|
Average |
62.5c |
94.2b |
92.5b |
113.7a |
86.8b |
64.8c |
4.05 |
0.001 |
|
Stage of growth (cm) |
||||||||
|
Day 30 |
67.3b |
54.7b |
87.6a |
100.3a |
72.4b |
48.3c |
6.50 |
0.01 |
|
Day 50 |
77.5c |
99.0c |
132.1b |
152.4a |
119.4b |
63.5c |
6.52 |
0.01 |
|
Day 65 |
119.4b |
153.7ab |
128.3ab |
167.6a |
124.5b |
74.7c |
6.58 |
0.01 |
|
Average |
88.14c |
102.4b |
116.1b |
140.2a |
98.6cc |
61.7c |
3.74 |
0.001 |
While red sunn hemp is new to the US, this warm-season annual legume has been used as green manure and cover crop in Brazil and Africa for many years. Crotalaria ochroleuca (red sunn hemp; Fig. 1) is an erect, highly branched annual or short-lived perennial herb. It can grow up to 2.0 meters tall. The plant has leaves divided into three narrow leaflets, usually smaller than 13 cm long and 3 cm wide. It is cultivated locally, primarily as a garden crop, for its edible leaves and beneficial companion properties. Red sunn hemp is also used for fiber, forage, and as a green manure cover crop. Its seed size is smaller than that of common sunn hemp, reducing the amount needed per acre and cutting overall costs. Red sunn hemp will fix nitrogen, suppress nematodes and weeds, and promote healthy soil.
Crotalaria juncea Crotalaria juncea, Thailand I Crotalaria juncea, Thailand II
(non-flowering sunn hemp)
Crotalaria juncea Crotalaria ochroleuca I Crotalaria ochroleuca II
(flowering sunn hemp) (Red sunn hemp I) (Red sunn hemp II)
Fig. 1. Six sunn hemp forage genotypes, Tuskegee, AL.
Table 2. The effect of forage genotypes and stage of growth on chemical composition.
|
Item |
Year |
Crotalaria juncea 1 (Flowering) |
Crotalaria juncea 2 (non-flowering) |
Crotalaria Thailand 1 |
Crotalaria Thailand 2 |
Crotalaria Thailand 3 |
Red sun hemp (Crotalaria ochroleuca) |
SEM |
P-value |
Forage x year int. |
|
CP |
Year 1 |
17.8 |
15.8 |
19.0 |
21.7 |
17.0 |
16.8 |
0.78 |
0.01 |
0.13 |
|
Year 2 |
15.5 |
10.7 |
11.7 |
16.4 |
12.3 |
12.5 |
0.78 |
0.01 |
||
|
ADF |
Year 1 |
38.6 |
43.6 |
41.7 |
36.2 |
38.8 |
43.9 |
0.96 |
0.01 |
0.01 |
|
Year 2 |
44.1 |
55.8 |
54.3 |
40.8 |
53.1 |
52.1 |
0.97 |
0.01 |
||
|
NDF |
Year 1 |
47.3 |
52.3 |
49.7 |
49.4 |
46.3 |
51.5 |
0.87 |
0.01 |
0.45 |
|
Year 2 |
52.8 |
64.9 |
62.6 |
49.3 |
49.5 |
59.0 |
0.98 |
0.01 |
||
|
TDN |
Year 1 |
60.0 |
59.0 |
59.5 |
59.5 |
60.0 |
59.0 |
0.32 |
0.05 |
0.001 |
|
Year 2 |
58.5 |
55.0 |
56.0 |
59.0 |
56.5 |
56.5 |
0.33 |
0.01 |
||
|
Ca |
Year 1 |
1.17 |
0.87 |
0.92 |
0.48 |
1.07 |
1.02 |
0.05 |
0.01 |
0.01 |
|
Year 2 |
1.15 |
0.65 |
0.77 |
0.65 |
0.67 |
0.83 |
0.06 |
0.01 |
||
|
P |
Year 1 |
0.23 |
0.24 |
0.30 |
0.30 |
0.19 |
0.21 |
0.01 |
0.01 |
0.22 |
|
Year 2 |
0.16 |
0.13 |
0.18 |
0.16 |
0.11 |
0.12 |
0.01 |
0.01 |
||
|
Mg |
Year 1 |
0.71 |
0.55 |
0.64 |
0.43 |
0.56 |
0.57 |
0.02 |
0.01 |
0.01 |
|
Year 2 |
0.56 |
0.33 |
0.39 |
0.40 |
0.33 |
0.41 |
0.02 |
0.01 |
CP = crude protein, ADF = acid detergent fiber, NDF = neutral detergent fiber, TDN = total digestible nutrients, Int = interaction.
On-farm pilot study
We planted selected sunn hemp seeds alongside Bermudagrass as a control forage for the on-farm pilot study. However, these grazing studies have faced challenges due to severe droughts at the project's onset (Fig. 2). We sowed sunn hemp and Bermudagrass in June 2022, 2023, and 2024 (Mr. Gooden's farm only in 2024; Fig. 3) at two producer farms in Alabama. Unfortunately, due to insufficient rainfall, most of the planted seeds have either not germinated or have died after germination. Thus, in 2024, during the farm trials at the Caprine Research and Education Unit at Tuskegee University, AL, we modified the sunn hemp forage by combining it with drought-resistant summer forages, such as sudangrass (SG) and pearl millet (PM), to achieve Objectives 1-2.
Fig. 2. Average precipitation during the study months from 2022 to 2024, Marcon and Lee County, AL
Bermudagrass 2022 Bermudagrass 2023 Bermudagrass 2024
Sunn hemp forage, 2022 Sunn hemp forage 2023 Sunn hemp forage 2024
Fig. 3. The effect of forage types (conventional bermudagrass vs. sunn hemp forage) on biomass production and animal performance, Opelika, Lee County, AL (Mr. Gooden’s farm). As seen in Fig. 3, not all the forage germinated or dried out due to a lack of rain during the project study period from 2022 to 2024.
Objective 1-2. To evaluate climate-resilient forages and their combination with various forages on plant biomass production, nutrient chemical composition, and rumen in vitro dry matter digestibility (IVDMD).
For this objective, six combinations of forages with different levels of sunn hemp (5%, 15%, and 20%) were planted in a 1-acre plot each during 2024 at the Caprine Research and Education Unit, Tuskegee University, AL, and have been completed. Six different forage combinations were evaluated for forage biomass production, nutrient chemical composition, and in vitro dry matter digestibility (IVDMD), with the results presented in Table 3 and Fig. 4. Mexican teosinte (TEO; Euchlaena mexicana) is a warm-season annual grass closely related to modern-day maize (Zea mays L). There is genomic evidence suggesting that Zea mexicana may be a predecessor of Zea mays (Yang et al., 2017; Kistler et al., 2020). Teosinte and sudan grass (SG) + sunn hemp (15 to 20%) combinations produce more biomass than Pearl millet + sunn hemp (5% and 15%) combinations, especially during heat or drought stress (Table 3; Fig. 4).
SG + sunn hemp combinations (15% and 20%) and TEO also provide highly digestible forages, as measured by IVDMD, and offer excellent nutritious forage that is readily utilized by livestock and wildlife in the summer (Table 3). The SG x SH 20% combinations yielded the highest biomass production (P < 0.01; 3520 t/ac) and IVDMD (62.2%) compared to other forage combinations in PM x SH 5% and PM x SH 15%. An annual teosinte species (TEO) that grows wild from Nayarit to Oaxaca, Mexico. Teosinte prefers well-drained, sandy loam. The ideal pH range is between 5.8 and 6.8, with a perfect soil temperature of 65°F. The seed is best planted between April and July, at a depth between 1/4" and 1 inch (Pecher seeds, 2025; 1609 Carpenter Crossing Rd, Fruitdale, AL). Teosinte provides cover that birds love; however, deer and rabbits will also enjoy it.
Pearl Millet (PM) + sunn hemp (15%) Teosinte (TEO) Sudangrass x sunn hemp (15%)
Sudangrass x sunn hemp (20%) Five way Livestock Mix PM x Sunn hemp (5%)
Fig. 4. The effect of different forage combinations on biomass production.
Pearl Millet (PM); Teosinte (TEO); Sudangrass (SG); Five ways Livestock Mix: Sunn Hemp 15 lb. + Red Ripper Peas 10 lb. + Prime 360 BMR (brown mid rib sorghums) 5 lbs. + Pearl Millet 10 lb. + Buckwheat 8 lb.
Table 3. The average biomass production (kg DM/ha) and chemical nutrition composition in a multi-forage system.
___________________________________________________________________________
Item IVDMD NDF ADF TDN Biomass production
(Kg DM/ac)
----------------------------------------------------------------------------------------------------------------
PM x SH 15 51.0b 51.4 41.9 50.9 2500b
TEO 61.7ab 52.0 41.4 51.3 2628ab
SG x SH 15 60.6ab 51.3 44.7 48.8 2664ab
SG x SH 20 62.2a 52.1 44.6 48.9 3520a
Five way 61.7ab 52.0 41.6 51.1 2600ab
PM x SH5 61.2ab 61.6 41.3 51.3 1840b
---------------------------------------------------------------------------------------------------------------
SEM 2.32 3.55 0.95 0.71 463.38
P-value 0.01 0.05 0.02 0.05 0.01
___________________________________________________________________________
Pear millet (PM) + Sunn hemp (SH) 15%; Teosinte (TEO): Sudan grass (SG) x sunn hemp 15%;
SG x SH 20%; 5 ways; Pear millet (PM) x sun hemp 5%; Five ways Livestock Mix: sunn Hemp 15 lb. + Red Ripper Peas 10 lb. + Prime 360 BMR (brown mid rib sorghums) 5 lbs. + Pearl Millet 10 lb. + Buckwheat 8 lb.
Objectives 2 and 3: To identify and assess economic characteristics and optimum economic return of different beef cattle production (grasses/legumes) systems.
. Annual warm-season legume forage, such as sunn hemp, grown in mixtures with other grasses (e.g., sudangrass), may offer advantages over other forage production options in hot and dry summers. We aimed to evaluate the effects of a multi-cropping summer forage and legume planting on forage yields, nutritive value, animal performance, and economic returns. The increased seeding costs associated with the legume component of legume–summer grass intercropping relative to the sole sunn hemp plant system can only be justified if intercrop yields are similar to or greater than sole sunn hemp forage, and the nutritive value is improved. Aasen et al. (2004) compared the economic suitability of sole barley cropping and pea–barley intercropping for forage production. Based on 2020 costs, they determined input costs to be $140/ha for barley sole crops and $190 to $202/ha for pea–barley intercrops. They concluded that minor improvements in the nutritional value of the pea–barley mixture were insufficient to offset the increased costs of mixed cropping relative to sole cropping. However, their study did not attempt to determine a dollar value for the higher nutritive value forage or costs for supplementing lower nutritive value feed, which might have altered their conclusions.
In our study, mean economic returns for summer were $583, $639, $788, and $809/ha and mean seed costs were $130, $112, 125, $128, $125, $110/ha for Pear millet (PM) + Sunn hemp (SH) 15%, Teosinte (TEO), sudangrass (SG) x Sunn hemp 15%, SG x SH 20%; 5 ways; Pear millet (PM) x sun hemp 5%, respectively. Total seed costs are $2.1/kg for PM seed, $2.2/kg for Sun hemp seed, 1.52/kg for SG, and $13.0/kg for TEO seed. Total forage values are based on the alfalfa pellet pricing formula. The fertilizer (16-16-15) cost was $0.81 per kilogram. Economic returns for summer forage were between $1,050 and $ 890/ha, and the mean seed costs were between $150 and $130 for multi-forage systems. Using proper forages for summer grazing, followed by winter forages, can provide a year-round foraging system. However, a combination of forages used for grazing should be selected to optimize livestock performance, enhance soil properties, and reduce methane or ammonia emissions from feces, while also reducing dependency on petrochemical fertilizers. We hope that combining legume sunn hemp forages with grasses will increase protein output, improve stocking rates, and replenish soil nitrogen, thereby reducing dependency on petroleum-based fertilizers.
These significant economic benefits were as follows:
- Warm-season legume forages, such as sunn hemp, can serve as an alternative forage crop in year-round forage systems. They provide high biomass production and excellent nutritional value as feed for animals and soil nitrogen for crop production, while also reducing fertilizer costs.
- Sunn hemp is a tropical legume that can produce a large amount of biomass, provide high nutritive value of forage, and fix large amounts of N, thus providing two benefits from one cover crop. Additionally, sunn hemp used as a cover crop or green manure can help reduce N fertilizer.
- Among the sunn hemp varieties, Crotalaria Thailand 2 sunn hemp produced the best biomass and higher protein content than other sunn hemp varieties, which can be used as a cover crop or green manure.
- These results indicated that SG + sunn hemp (15% and 20%) combinations could be more beneficial to provide high biomass production and provide sufficient nutrients for ruminants to maintain optimum weight gain in grazing animals. The SG + 5% sunn hemp combination did not impact additional biomass production; therefore, a minimum of 15% sunn hemp is recommended for a multi-forage system to improve maximum biomass production per acre.
- Due to severe drought weather, we were unable to conduct on-farm trials on soil quality and animal performance.
- It appears that sunn hemp or sunn hemp combination with other summer cover crops can fit nicely into a sustainable livestock production system in Alabama.
Take Home Messages
Using proper forages for summer grazing, followed by winter forages, can provide a year-round foraging system. However, a combination of forages used for grazing should be selected to optimize animal performance, enhance soil properties, and reduce methane or ammonia emissions from feces, while also reducing dependency on petrochemical fertilizers. We hope that combining legume sunn hemp forages with grasses will increase protein output and restore nitrogen in the soil, thus reducing dependency on petroleum-based fertilizers. We will continue working with these farmers to adopt summer and winter grazing systems. Annual warm-season legume forage, such as sunn hemp (more than 15%), grown in mixtures with other grasses (e.g., sudangrass), may offer advantages over other forage production options in hot and dry summers.
Note: A testimonial from the farmer is provided (from Gerald Gooden).
To Whom It May Concern
The winter is over, the animals are in their respective pastures, and I get to thank you! Tuskegee University has supported my efforts to raise quality beef cattle here at our Farm. Over the last two years, we experienced an unusually severe drought (2022-2024) during the summer grazing seasons, which dramatically impacted forage availability and cattle production.
From the beginning in 2022 to the present, the professors (Dr. Min) and staff of the College of Agricultural, Environmental, and Nutrition Sciences have provided me with invaluable support that has helped me overcome many difficult times. They have provided me with information on areas that are much-needed, such as forage seeds and fertilizers, cross-fencing materials, herd management training, pasture maintenance, nutrition, parasite control, health issues, educational opportunities, record-keeping, soil amendment, and research programs. This means a great deal to small farmers like me. Many challenges provide opportunities for doubts and failure. Without the information and assistance I have received, the success rate for small farmers is minimal. If you have any questions regarding this matter, please do not hesitate to contact me at your convenience
Yours sincerely.
05/10/2025
Gerald Gooden
1199 Lee Road, Opelika, Al. 36804
334-703-43161
E-mail: ggooden@bellsouth.net
Educational & Outreach Activities
Participation Summary:
Extension and Outreach Program.
A one-day pasture walk program was organized with several producers in attendance. The program began with a pasture walk, followed by a question-and-answer session. Much of the interest was focused on sunn hemp and multi-forage systems. Producers were also requesting us to carry out further studies with sunn hemp that can produce seeds. The final animal production performance based on these forages will be disseminated to a larger audience and other stakeholders through fact sheets, popular articles, and to the scientific community through refereed journal articles.
- Impacts and Contributions/Outcomes
We believe that utilizing proper forages for summer legumes, followed by winter grasses, can create a year-round forage system. However, a combination of forages used for grazing should be selected to optimize animal performance, enhance soil properties, and reduce methane or ammonia emissions from feces, while also reducing dependency on petrochemical fertilizers. We hope that combining legume forages such as sunn hemp with grasses will increase protein output and restore 25-30% more nitrogen and organic matter in the soil, thereby reducing dependency on petroleum-based fertilizers.
- Summary
- Pasture feeding is safe and relatively low-cost.
- Warm-season legume forages, such as sun hemp forage, can be used as an alternative forage crop in year-round forage systems, providing high-nutritive-value feed for animals and soil nitrogen for crop production, while reducing fertilizer costs.
- Summer forages such as Sunn hemp and its combination or multi-forage system that can both produce a large amount of biomass, provide high nutritive value of forage, and fix 25-30% more soil nitrogen and organic matter, thus providing two benefits from one cover crop and help reduce N fertilizer. It appears that legume forages in warm-season forages can be effectively integrated into a sustainable beef cattle production system in Alabama.
Learning Outcomes
Project Outcomes
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