Stockpiling forages can extend grazing season

Stockpiling forages can extend grazing season

*Dr. Matt Poore is a professor and extension ruminant nutrition specialist at North Carolina State University. To expedite answers to questions concerning this column, please direct inquiries to Feedstuffs, Bottom Line of Nutrition, 5810 W. 78th St., Suite 200, Bloomington, Minn. 55439, or email [email protected]

IT is no secret that the cost of raising cows has increased dramatically, and producers have responded by exploring new systems that extend the grazing season while reducing their dependence on harvested forages.

Practices such as swath grazing, bale grazing and "stockpiling" are of current interest.

Stockpiling is useful in situations where standing forage can carry into the winter months and still maintain good forage quality.

Any forage can be stockpiled, and in the West, it is common for cows to graze nearly year-round on native forages. In the Midwest and East, a wide variety of forages are used, including crop residues (corn stalks), bermudagrass, fescue and grass mixtures.

It is important to note that the quality of these forages varies dramatically, and when planning a feeding program, information on the quality of the standing forage is needed.

In my program at North Carolina State University, we have been evaluating optimal supplementation programs and the importance of endophyte in stockpiled fescue systems. We have focused on fall-born developing replacement beef heifers as a general research model.

A review of the literature (Poore et al., 2000) showed that there were limited data on the heifers' response to supplementation and the importance of the fescue endophyte in stockpiled fescue systems.

 

Endophyte infection

Over the last decade, several research groups showed that ergot alkaloids in infected stockpiled fescue decline with time, reaching low levels by midwinter (Poore and Drewnoski, 2010).

In Missouri, Curtis and Kallenbach (2007) showed that cows lost more weight and body condition through the winter on pastures with higher infection rates, but breeding rates and weaning weights of calves were not influenced.

In North Carolina, a five-year study compared toxic, endophyte-free and nontoxic fescue for stockpiling systems (Drewnoski et al., 2009). Grazing was initiated during early December and continued through February.

Heifers gained an average of 1.22 lb. per day, and there was no difference among the fescue types. Heifers grazing toxic fescue were affected, as evidenced by a reduced prolactin concentration, but the low level of toxin and cool conditions resulted in no depression in performance.

In both studies, forage yield was higher for the more toxic fescue.

As a result of these studies, it is recommended that producers wait to graze stockpiled fescue in midwinter until after toxin levels have declined.

 

Supplementation

One observation made in my program's long-term study was that performance varied dramatically from year to year.

Average daily gain (ADG) was 1.22 lb. per day, but the range was from 0.77 lb. to 1.80 lb. per day. Clearly, in some years, heifers would need significant supplementation to reach a desired breeding weight, while in other years, development would be adequate without supplementation.

Higher performance was related to higher crude protein and total digestible nutrient levels in forage at the start of the grazing season. Blood urea nitrogen levels suggested that degradable protein might be a limitation despite an apparently adequate forage protein concentration, perhaps because of low forage intake.

In a two-year study (Poore et al., 2006), heifers grazing infected stockpiled fescue were supplemented with 0.33% of bodyweight of whole cottonseed.

In the first year, forage crude protein (and blood urea nitrogen) was high at 17.7%, and the ADG response of the heifers was what would be expected for an energy supplement — 1.01 lb. versus 1.23 lb. per day. In the second year, crude protein was lower at 12.8%, and ADG improved from 0.51 lb. to 1.01 lb. per day as a result of supplementation.

Others have noted that heifers might respond to protein supplementation in some situations but not in others, primarily based on the crude protein content of the forage (Poore and Drewnoski, 2010).

A two-year study (Poore et al., 2012) was recently completed that evaluated supplementing heifers (initially 597 lb. with a body condition score of 5.2) with 0%, 0.5%, 1.0% or 1.5% of bodyweight of a 50/50 mix of soybean hulls and corn gluten feed. Heifers were grazed for 56 days before being synchronized and bred by artificial insemination, followed by a cleanup bull. Key results are shown in the Table.

Heifers supplemented at increased levels showed a linear increase in ADG and body condition score. Breeding rate following artificial insemination increased linearly, with a tendency for a quadratic effect. Likewise, there was a linear and quadratic increase in the overall breeding rate, with a substantial increase from the first level of supplementation and no increase thereafter.

Increasing the supplementation level dramatically increased gain per acre, but because there was little change in forage intake until the highest level of supplementation, heifer days per acre showed a much lower response.

Based on these results, it appears that developing heifers with a low level of supplement would economically improve reproductive performance, while the higher levels might be more appropriate for stocker heifers destined for finishing.

My current work is focusing on low-level supplementation and increasing forage allowance as strategies to optimize reproductive performance.

 

Growth and reproductive performance of heifers grazing stockpiled fescue, as influenced by supplemental feeding level

 

-Supplement level, % of bodyweight-

Std. error

-P-value-

Variable

0

0.5

1.0

1.5

of means

Linear

Quadratic

ADG, lb./day

1.17

1.64

2.05

2.40

0.09

0.05

NS

Body condition score change

0.43

0.48

0.75

0.97

0.06

0.01

0.16

Artificial insemination breeding rate, %

32.3

51.0

65.6

60.4

8.17

0.03

0.16

Overall breeding rate, %

77.1

95.8

95.8

90.6

5.13

0.08

0.03

Gain per acre, lb.

195

317

416

566

25.4

0.01

NS

Heifer days per acre

180

201

206

243

9.0

0.01

NS

NS = non-significant.

 

Producer adoption

While there is increasing interest in managed stockpiling across the fescue belt and in other regions, the adoption rate has been slow. Producers understand that extending the grazing season will reduce their costs, but many lack the skills and infrastructure to implement the practice.

To be successful, producers need to avoid overgrazing fields to be stockpiled during the previous summer and put out nitrogen on a timely basis. After that, it is critical to stay off pastures until after the start of winter (with toxic fescue), which may require some hay feeding during the fall.

Finally, an effort is needed to manage grazing because allowing animals unlimited access to stockpiled forage is quite inefficient.

To stimulate the adoption of stockpiling in the area, on-farm demonstrations were conducted during 2009, 2010 and 2011. My team worked with producers who had fescue they wanted to stockpile, and we provided an incentive package of portable electric fence supplies. We collected data on forage mass and quality and conducted a grazing workshop at each site.

It quickly became clear that major limitations included understanding and employing the temporary electric fencing. A team consisting of the local extension agent and a state or federal conservationist worked carefully with each cooperator to teach them to implement strip-grazing. At each workshop, participants were given time to practice with temporary electric fence techniques.

We conducted 31 demonstrations on a total of 25 farms. Most of these farms had fall-calving cows, with the average herd size being 25. In almost all cases, cows either maintained or increased their body condition score. A total of 149 forage samples contained an average 14.4% crude protein and 68% total digestible nutrients. Total forage mass available for grazing averaged 2,620 lb. per acre, and producers realized 106 cow grazing days per acre.

Based on all costs, the cow cost on stockpiled fescue was $1.31 per day, compared to a calculated $2.40 for a standard hay feeding program. As a result of the project, nearly all participating producers and many of the workshop participants have adopted the stockpiling practice.

 

The Bottom Line

Stockpiling and managed stripgrazing are gaining popularity among producers across the country. Forages will vary regionally, but improved grazing management will be the key to success in most situations.

Tall fescue is an excellent forage to stockpile, and more efficient use of this resource will be advantageous to cow/calf producers in the fescue belt.

Additional research is needed to improve recommendations on optimal supplementation programs for growing cattle, but stockpiled fescue appears to be an ideal winter forage for brood cows with only mineral supplementation.

Because new management skills are required to successfully implement a stockpiling program, targeted education is needed to speed up the adoption rate of this system.

 

References

Curtis, L.E., and R.L. Kallenbach. 2007. Endophyte infection level of tall fescue stockpiled for winter grazing does not alter the gain of calves nursing lactating beef cows. J. Anim. Sci. 85:2346.

Drewnoski, M.E., E.J. Oliphant, B.T. Marshall, M.H. Poore, J.T. Green and M.E. Hockett. 2009. Performance of growing cattle grazing stockpiled Jesup tall fescue with varying endophyte status. J. Anim. Sci. 87:1034.

Poore, M.H., and M.E. Drewnoski. 2010. Review: Utilization of stockpiled tall fescue in winter grazing systems for beef cattle. Prof. Anim. Sci. 26:142-149.

Poore, M.H., G.A. Benson, M.E. Scott and J.T. Green. 2000. Production and utilization of stockpiled fescue to reduce beef cattle production costs. J. Anim. Sci. 79(Suppl.):1-11.

Poore, M.H., M.E. Scott and J.T. Green Jr. 2006. Performance of beef heifers grazing stockpiled fescue as influenced by supplemental whole cottonseed. J. Anim. Sci. 84:1613.

Poore, M.H., A.D. Shaeffer, S.R. Freeman, J.M. Scruggs, G.R. Hansen, M.L. Alley, C.S. Whisnant and M.E. Drewnoski. 2012. Supplemental concentrate for heifers grazing stockpiled fescue. J. Anim. Sci. 90(Suppl. 1):15 (abstr). 

Volume:85 Issue:47

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