Impacts of Ionophore Supplementation and Corn Residue Management on Profitability of Grazing Rye with Growing Calves within an Integrated Production System

Final report for GNC16-220

Project Type: Graduate Student
Funds awarded in 2016: $11,997.00
Projected End Date: 08/31/2018
Grant Recipient: University of Nebraska - Lincoln
Region: North Central
State: Nebraska
Graduate Student:
Faculty Advisor:
Dr. Mary Drewnoski
University of Nebraska - Lincoln
Expand All

Project Information

Summary:

With a projected global population over 10 billion by 2050, the United States must increase agricultural production while conserving diminishing land and water resources to meet future food demand. The SARE North Central region of the U.S. produces 85.5% of the country’s corn grain and approximately 30% of the finished beef cattle; therefore, this region could benefit from the opportunity to integrate crop and livestock production by grazing cattle on corn residue and cover crops. Although rye is a common cover crop in Nebraska, there is no data regarding its establishment, yield, and economic feasibility as a forage for backgrounding calves in early spring. Ionophores can improve feed efficiency through increased gain and decreased intake, as well as reduce methane emissions in cattle fed high-forage diets. No current information exists on ionophore supplementation of cattle grazing cereal rye in spring. We hypothesize that supplementing growing calves with ionophores will improve average daily gain at equal stocking rates, leading to conserved cover crop biomass, improved soil cover, and greater profitability for producers. The goal of this study is to identify the utility of grazing rye in an integrated system, and whether management strategies such as ionophore supplementation and corn residue removal are potential management strategies to enhance the productivity and economic returns of rye grazing system. Project success will be evaluated through producer feedback, economic analysis, and field day attendance and participant feedback. The long-term objective is to develop recommendations for North Central agricultural producers on possible strategies to feasibly implement a sustainable integrated crop-livestock system using cattle and cereal rye in a traditional corn-soybean rotation. These strategies can enhance the diversification and economic resiliency of North Central agriculture in order to meet the future challenges of global food demand.

Project Objectives:

Our specific aims are to 1) assess ionophore supplementation effects on growing calf performance when backgrounded on cereal rye in spring; 1a) determine the effect of ionophore supplementation on cattle intake by measuring rye biomass disappearance over the grazing period; 1b) evaluate the economic implications of ionophore supplementation on a single enterprise (cattle) and whole system level (crop-livestock integration); and 2) assess the impact of two different types of fall corn residue management (removal by baling or grazing) on rye forage production, ground cover and animal performance; and 3) the effect of rye growth and grazing on subsequent cash crop yields to conduct a whole system profitability analysis.

Research

Materials and methods:

For the first year of the two year study conducted near Mead, NE, two fields (averaging 103 ac each) were separated into three blocks, and each block included four treatments: a negative control strip, not planted with cereal rye (5.5 ± 1.6 ac), a positive control strip planted with cereal rye but not grazed (5.1 ± 1.5 ac), and two pastures (10.2 ± 3.0 ac) planted with rye and grazed. For each block, cattle in one pasture were provided free choice trace mineral supplement without a monensin ionophore, and the other pasture provided a mineral with monensin ionophore (4 oz target intake to supply 200 mg/h/d). Field 1 was in a corn-soybean-wheat crop rotation, with the most recent harvest being wheat harvested in July of 2016, followed by a hay crop of sorghum-sudan grass, which was swathed on September 26, 2016 and baled after approximately 2 weeks of drying in October. Field 2 was in a corn-soybean rotation, with the most recent harvest being soybeans harvested on October 18, 2016. Elbon cereal rye was planted on October 28, 2016 at a rate of 70 lb/ac, and fertilized with 11-52-0 at a rate of 40 lb/ac on November 15, 2016.

In spring of 2017, when rye had reached approximately 5 inches of growth, cattle were turned out for grazing. Prior to turn out, 184 commercial crossbred steers (729 ± 19 lb BW) were limit fed for 7 days on a diet of 50% Sweetbran and 50% alfalfa hay, and three day empty body weights were taken to randomly assign cattle to treatment. Based on rye biomass production, Field 1 was stocked at a rate of 0.9 hd/ac and Field 2 was stocked at a rate of 1.8 hd/ac. Cattle grazed for a total of 22 days, with two pastures having half the number of cattle removed at 14 d. Cattle were limit fed at the end of the trial for 5 days on the same diet as stated previously to equalize gut fill, and three day BW were taken. Weights were adjusted to account for 1 lb/d gain during the limit fed periods.

Year 2 of the project began after corn harvest in 2017. Elbon cereal rye was planted at a target rate of 80 lb/ac on November 1st for Field 1 and November 5th and 6th, 2017 for Field 2. Corn residue treatments were applied to the fields during the winter, with baling of the corn residue occurring on Nov 7th and grazing reside removal beginning on January 31, 2018. Grazing residue removal occurred with 300 steers (approximately 650 lbs) targeting a 25% removal rate, and cattle grazed each block between 4-6 days. These cattle were used as a treatment application, and were not weighed as part of the study. Rye was fertilized with 11-52-0 at a rate of 40#/ac on March 29th, 2018.

Residue cover and biomass was sampled on March 27th, 2018 using meter frames and 100 ft transects. Rye emergence was measured on April 19th, 2018 using frequency frame transects. At this time, it was determined that the rye growth was not sufficient to maintain cattle grazing for an extended period this spring, so no cattle gains were measured for this year of the study. Plots were grazed for treatment application only from May 7th-19th, and rye biomass samples were taken from all plots on the same day cattle were removed from fields.

Research results and discussion:

 In Year 1 of this study, the cereal rye performed differently between the two fields, despite planting and fertilizing at the same time (Table 3). The average between the two at the start of grazing on March 27 was 450 lb/ac DM, but Field 1 was measured at 411 ± 20 lb/ac DM, and Field 2 was measured at 492 ± 20 lb/ac DM. Field 1 established slower, and had less biomass at grazing than Field 2. This can likely be attributed to differences in soil moisture between the two fields. Field 1 entered the study after a wheat harvest followed by a short-season crop of sorghum-sudan hay, and Field 2 entered the study after a soybean harvest. Although not measured, the additional hay crop is suspected to have had an impact on rye establishment and subsequent spring growth because it appeared there was reduced soil moisture. The stocking rate and number of grazing days resulted in a harvest of 0.47 AUM/ac in Field 1 and 1.06 AUM/ac in Field 2.

There was no statistical difference between treatments for the 2017 corn harvest yield (Table 1), but some numerical differences were observed. The rye was killed at planting which may have contributed to the numerically lower corn yields in the grazed and ungrazed rye treatments. There was a significant difference between treatment effects on corn plant populations. Ungrazed planted rye plots appeared to have the greatest plant populations, with no difference between the no rye or grazed rye treatments. Based on this study, no negative impacts on corn yield or establishment were observed, with planting rye and not grazing it.

Over the brief 22 day grazing period, steers gained an average of 3.2 lbs/day (Table 2) and ADG did not differ between the two fields, all starting at an average of 733 lbs. This was greater than the 2.0 lbs/day expected gain seen previously in other spring grazing studies done with wheat. Total gain per acre averaged 98 lbs/ac, although there was a significant field effect with Field 1 means averaging 60 lb/ac and Field 2 averaging 136 lb/ac. This was expected, since Field 2 produced more biomass and was stocked at nearly double the stocking rate. In this study, cattle demonstrated considerable growth over a short period of time, indicating that cattle can perform well on spring rye maintained in a vegetative state.

 Although cattle performed well, there was no significant difference in ADG, or gain/ac between the two supplement treatments (Table 2). Additionally, no difference was observed in rye biomass at the end of the grazing period (Table 3).

 Planting rye and grazing resulted in a seed cost of $16.80/ac, fertilizer cost of $10.00/ac, and custom drilling and application costs of $13.36/ac and $6.00/ac. Cattle costs included fencing at $4.40/ac, mineral costs of $0.07/hd/d for control and $0.08/hd/d for ionophore, and $0.10/hd/d for yardage costs. The price of the calves per pound did not change during the short time period, and was $140/cwt. There was no significant difference between grazing mineral treatments in returns (Table 4). There was a difference between fields, due to the differences in stocking rate with Field 1 returning $32.53/ac and Field 2 returning $111.7/ac. Regardless of grazing management strategy, incorporating cattle into this system offset the increased costs of planting the rye by providing additional returns.

There was no statistical difference (Table 5) in residue biomass, although there was a numerically greater amount of corn residue remaining in the grazed blocks, potentially leading to the significantly greater amount of ground cover in those blocks compared to the baled blocks. This is not entirely unexpected given that the raking process in baling would leave more ground bare compared to grazing. However, it should be noted that 51.6% cover is still quite high for what has been previously observed for ground cover after raking and baling, suggesting less aggressive raking process in this study. Overall, the rye was planted with statistically equal amounts of residue, but had significantly more cover in the grazed blocks.

There was a significant interaction (Table 6) between fields in biomass emergence, with no difference between baled and grazed treatments in Field 2, but a significantly greater emergence of rye in the baled blocks compared to the grazed. There were several severe cold weather events in the spring of 2018, which reduced the growth of both fields compared to the previous Year 1. As such, in Field 1 there was insufficient biomass to support animal grazing at the target turn-out time, so animals were not grazed on this field, and these numbers were not included in the biomass estimates. There was a tendency for an effect of corn residue treatment on rye biomass production as measured in Field 2, and no interaction between fall treatments and spring grazing were detected.

Overall, some differences in ground cover and emergence of rye were observed as a result of residue removal method, but it appeared to have only minimal effect on rye biomass performance. However, weather was a complicating factor in Year 2.

 

Table 1. Results of corn yield and corn plant population estimates from the first year of planting and grazing cereal rye.

 

Grazed Control

Grazed Ionophore

No-graze, Rye

No-graze, No Rye

SEM

P-value

Corn Yield, bu/ac1

189

203

204

211

14.1

0.59

Stand count-early, plants/ac2

31,370b

32,463ab

33,667a

32,296b

442

0.02

Stand count-harvest, plants/ac3

31,167b

33,556b

35,778a

32,944b

1201

0.10

1 Collected via hand-harvest at black layer in a 17.5 ft row at three different points per plot, and grain yield on DM basis was adjusted to 85% moisture. Due to replant date with different hybrids, only data from Field 1 was analyzed and reported.

2 Counts were collected at V8 stage as an average of three adjacent rows in a 17.5 ft length at three different points per plot. Plant population estimates from plot averages divided by 1/1000th of an acre.  Means that share a letter are not significantly different from each other, and italicized letters indicate a tendency to be significant.

3 Counts were collected at hand harvest (black layer). Means that share a letter are not significantly different from each other.

 

Table 2. Cattle performance over 22 days of grazing spring cereal rye with and without an ionophore supplement.

 

Grazed Control

Grazed Ionophore

SEM

P-value

Average Daily Gain, lb/d1

3.1

3.3

0.24

0.60

Total gain per acre, lb/ac2

98.8

96.7

7.4

0.84

1 Cattle were limit fed for 7 days prior to turnout and for 5 days at the end of the grazing period to equalize and account for gut fill. Initial and final BW was adjusted to account for gain during these periods.

2 Significant field effect (P <0.01)

Table 3. Rye biomass production in tons of DM/ac at the beginning and end of the grazing period.

 

Grazed Control

Grazed Ionophore

No-graze, Rye

No-graze, No Rye

SEM

P-value

Rye Biomass before grazing,

lb DM/ac1

463

441

19.5

0.43

Rye Biomass after grazing,

lb DM/ac2

503b

538b

1901a

54

0.03

1 Data was collected on March 27th, one week prior to turn out via drop plates. Some volunteer wheat was observed in Field 1. There was a significant (P= 0.02) difference between Field 1 (411 lb DM/ac) and Field 2 (493 lb DM/ac).

2 Data was collected on May 5th, one week after cattle terminated grazing via drop plate.

Table 4. Economic returns for different cattle management strategies on spring-grazed rye over the course of the grazing period.

 

 

Grazed Control

Grazed Ionophore

SEM

P-value

Returns, $/hd1

37.63

48.68

6.55

0.31

Returns, $/ac

62.81

70.09

8.00

0.56

1 Seed cost of $16.80/ac, fertilizer cost of $10.00/ac, custom drilling and application costs of $13.36/ac and $6.00/ac. Cattle cost included fencing at $4.40/ac, mineral costs of $0.07/hd/d for control and $0.08/hd/d for ionophore, and $0.10/hd/d for yardage costs with calf price at $140/cwt.

Table 5. Effect of corn residue removal method on ground cover and residue biomass prior to rye emergence.

 

 

Baled Removal

Grazed Removal

SEM

P-value

Residue Biomass, ton DM/ac

4.3

5.4

0.74

0.32

Residue Ground Cover, %1

51.6

82.6

1.12

< 0.01

1 Only corn residue cover was counted in 100 ft transects, rye biomass from the previous spring was not included.

Table 6. Effect of corn residue removal method on fall-planted rye performance the following spring.

 

 

Baled Removal

Grazed Removal

SEM

P-value

Rye Emergence, %

Field 1

62.2

22.0

4.08

< 0.01

(Interaction)

Field 2

48.5

48.5

 

 

 

 

 

 

Rye Biomass, ton DM/ac1

Control

1.3

1.1

0.24

0.10

Grazed

0.6

0.8

1 Due to lack of available biomass Field 1, only Field 2 was grazed and sampled for biomass. Therefore, these estimates do not include Field 1. Control refers to un-grazed strips and grazed refers to plots where cattle were grazed in Spring of 2018 for 12 days. Samples were taken the day cattle were pulled on May 19th, 2018.

Participation Summary
1 Farmer participating in research

Educational & Outreach Activities

1 Curricula, factsheets or educational tools
1 Webinars / talks / presentations
1 Workshop field days

Participation Summary

30 Farmers
5 Ag professionals participated

Project Outcomes

Project outcomes:

With this project, we were able to demonstrate the logistical feasibility of implementing a spring-grazed cover crop in an existing cash crop system. Although there was variability in the success of implementation depending on weather events, there is evidence to suggest based on our work that this system can be economically beneficial to some producers without detracting from the performance of their cash crop. 

Knowledge Gained:

This study has been contributed greatly to our body of knowledge regarding integrated crop-livestock systems, particularly with regards to grazing cover crops. Aside from the data generated from this study, we were able to learn a great deal about how best to incorporate spring-grazing of cereal rye into Midwest cropping systems. The first year of the study, we observed that rotational grazing might extend the grazing period due to the rapid re-growth observed at corn planting. Even the set-backs of not being able to graze cattle the second year of the study enhanced our understanding of how weather and timing of planting will contribute to the success of this particular strategy. Work in this area of research will continue to build on our understanding of how best to utilize this system.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.