Article Contents
Article Contents

# Effect of rotational grazing on plant and animal production

The second author is supported by NSF grant DMS-1313243.
• It is a common understanding that rotational cattle grazing provides better yields than continuous grazing, but a quantitative analysis is lacking in agricultural literature. In rotational grazing, cattle periodically move among paddocks in contrast to continuous grazing, in which the cattle graze on a single plot for the entire grazing season. We construct a differential equation model of vegetation grazing on a fixed area to show that production yields and stockpiled forage are greater for rotational grazing than continuous grazing. Our results show that both the number of cattle per acre and stockpiled forage increase for many rotational configurations.

Mathematics Subject Classification: Primary: 58F15, 58F17; Secondary: 53C35.

 Citation:

• Figure 1.  Left: Growth rate of the grass and consumption rate by the cattle for continuous grazing. Here the growth rate $G(V)$ and the grazing rate $H\cdot c(V)$ are defined as in (2.1) and (2.2), with parameter values given as in Table 1 and $H=1.06$, $0.6$ and $0.2$ respectively. Right: A forage ($V$) versus cattle ($H$) bifurcation diagram for the continuous grazing system

Figure 2.  Illustration of continuous grazing (left), and rotational grazing (right).

Figure 3.  Amount of forage in a sustainable rotational configuration where $3$ out of $4$ paddocks are grazed. Here (2.7) and (2.8) are used for integration, $(n,m,T)=(4,3,10)$, $H=1.3$ and $T_{total}=365$ days.

Figure 4.  Amount of forage in a sustainable rotational configuration where $3$ out of $4$ paddocks are grazed. Here (2.7) and (2.8) are used for integration, $(n,m,T)=(4,3,10)$, $H=1.28$ and $T_{total}=3650$ days.

Figure 5.  Maximum $H$ for different paddock configurations and $T$. Here the horizontal axis is the rotation period $T$, the vertical axis is the maximum sustainable cattle number $H_{max}^R(T)$, and the legend shows $m: n$ (the number of paddocks grazed versus the number of total paddock). The horizontal line is $1.0631$ head of cattle per acre, which is from continuous grazing. Here $T_{total}=365$ is used.

Figure 6.  Maximum $V$ for different paddock configurations and $T$. Here the horizontal axis is the rotation period $T$, the vertical axis is the forage amount $V_S^R(T)$ when achieving the maximum sustainable cattle number $H_{max}^R(T)$, and the key is $m: n$ (the number of paddocks grazed versus the number of total paddock). The horizontal line is the forage amount when achieving the maximum sustainable cattle number $H_{max}$ for continuous grazing.

Figure 7.  Cattle and stockpiled forage plotted against the grazing ratio for a $15$-day rotation period. Here the horizontal axis is the grazing ratio of the rotational scheme, and the vertical axis is the maximum sustainable cattle number $H_{max}^R(T)$ and associated forage amount $V_S^R(T)$.

Table 1.  Table of variables and parameters in the equations.

 Variable Meaning Units $t$ time days $V_j(t)$ grass biomass in paddock $j$ pounds/acre Parameter Meaning Units Value Reference $V_{max}$ grass carrying capacity pounds/acre $2400$ [21] $g_{max}$ maximum growth rate per capita rate per capita day$^{-1}$ $0.05625$ [14] $c_{max}$ maximum consumption rate per head of cattle pounds/(acre$\cdot$day) $35$ [1,2] $K$ half-saturation value pounds/acre $120$ $H_j$ number of cattle per acre in paddock $j$ cattle/acre
•  [1] How Much Feed Will My Cow Eat? Alberta Agricultural and Rural Development Edmonton, Alberta, 2003, Available from: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/faq7811 [2] Raising Cattle for Beef Production and Beef Safety, Cattlemen's Beef Board and National Cattlemen's Beef Association, Centennial, Colorado, 2013, Available from: http://www.explorebeef.org/raisingbeef.aspx [3] Using the Animal Unit Month (AUM) Effectively, Alberta Agricultural and Rural Development, Edmonton, Alberta, 2001, Available from: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex1201 [4] L. I. Aniţa, S. Aniţa and V. Arnăutu, Global behavior for an age-dependent population model with logistic term and periodic vital rates, Appl. Math. Comput., 206 (2008), 368-379.  doi: 10.1016/j.amc.2008.09.016. [5] L. I. Aniţa, S. Aniţa and V. Arnăutu, Optimal harvesting for periodic age-dependent population dynamics with logistic term, Appl. Math. Comput., 215 (2009), 2701-2715.  doi: 10.1016/j.amc.2009.09.010. [6] S. K. Bamhart, Estimating available pasture forage, Iowa State University Extension College of Agriculture, Ames, Iowa, 2009. [7] S. Behringer and T. Upmann, Optimal harvesting of a spatial renewable resource, J. Econ. Dyn. Control., 42 (2014), 105-120.  doi: 10.1016/j.jedc.2014.03.008. [8] A. O. Belyakov, A. A. Davydov and V. M. Veliov, Optimal cyclic exploitation of renewable resources, J. Dyn. Control Syst., 21 (2015), 475-494.  doi: 10.1007/s10883-015-9271-x. [9] A. O. Belyakov and V. M. Veliov, Constant versus periodic fishing: Age structured optimal control approach, Math. Model. Nat. Phenom., 9 (2014), 20-37.  doi: 10.1051/mmnp/20149403. [10] Briske and Rotational grazing on rangelands: Reconciliation of perception, et al., Rotational grazing on rangelands: Reconciliation of perception and experimental evidence, Rang. Ecol. & Mana., 61 (2008), 3-17.  doi: 10.2111/06-159R.1. [11] L. Fu, T. Bo, G. Du and X. Zheng, Modeling the responses of grassland vegetation coverage to grazing disturbance in an alpine meadow, Ecol. Modelling, 247 (2012), 221-232.  doi: 10.1016/j.ecolmodel.2012.08.027. [12] R. K. Heitschmidt, S. L. Dowhower and J. W. Walker, 14-vs. 42-paddock rotational grazing: Aboveground biomass dynamics, forage production, and harvest efficiency, Jour. Range Mana., 40 (1987), 216-223.  doi: 10.2307/3899082. [13] C. S. Holling, Some characteristics of simple types of predation and parasitism, The Canadian Entomologist, 91 (1959), 385-398.  doi: 10.4039/Ent91385-7. [14] C. Hurtado-Uria, D. Hennessy, L. Shalloo, R. Schulte, L. Delaby and D. O'Connor, Evaluation of three grass growth models to predict grass growth in Ireland, Jour. Agri. Sci., 151 (2013), 91-104.  doi: 10.1017/S0021859612000317. [15] I. R. Johnson, T. E. Ameziane and J. H. M. Thornley, A model of grass growth, Annals of Botany, 51 (1983), 599-609.  doi: 10.1093/oxfordjournals.aob.a086506. [16] R. Kallenbach, Calculating stocking rates of cows, High Plains Journal, 2010. [17] R. Lemus, Developing a grazing system, Mississippi State University Extension, Mississippi State, Mississippi, 2008. [18] R. M. May, Thresholds and breakpoints in ecosystems with a multiplicity of stable states, Nature, 269 (1977), 471-477.  doi: 10.1038/269471a0. [19] I. Noy-Meir, Stability of grazing systems: An application of predator-prey graphs, The Journal of Ecology, 63 (1975), 459-481.  doi: 10.2307/2258730. [20] I. Noy-Meir, Rotational grazing in a continuously growing pasture: A simple model, Agri. Systems., 1 (1976), 87-112.  doi: 10.1016/0308-521X(76)90009-3. [21] E. B. Rayburn, Number and size of paddocks in a grazing system, West Virginia University Extension Service, Morgantown, West Virginia. 1992. [22] J. P. Ritten, W. M. Frasier, C. T. Bastian and S. T. Gray, Optimal rangeland stocking decisions under stochastic and climate-impacted weather, Amer. Jour. Agri. Econ., 92 (2010), 1242-1255.  doi: 10.1093/ajae/aaq052. [23] A. Savory and D. P. Stanley, The Savory grazing method, Rangelands, 2 (1980), 234-237. [24] N. F. Sayre, Viewpoint: The need for qualitative research to understand ranch management, Rang. Ecol. & Mana., 57 (2004), 668-674. [25] M. Scheffer, Critical transitions in nature and society, Princeton University Press, Princeton, New Jersey, 2009. [26] M. Scheffer, S. Carpenter, J. A. Foley, C. Folke and B. Walker, Catastrophic shifts in ecosystems, Nature, 413 (2001), 591-596.  doi: 10.1038/35098000. [27] R. Smith, G. Lacefield, R. Burris, D. Ditsch, B. Coleman, J. Lehmkuhler and J. Henning, Rotational grazing, University of Kentucky College of Agriculture; Lexington, Kentucky, 2011. [28] J. Sprinkle and D. Bailey, How many animals can I graze on my pasture?, The University of Arizona Cooperative Extension, Tucson, Arizona, 2004.

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