Carlos Manuel Méndez Acosta
Martin Fraguio
UNIVERSIDAD CATOLICA ARGENTINA
Facultad de Ciencias Agrarias
Freire 183
1426-Buenos Aires-Argentina
Phone: 54 11 4553-5235
e-mail address: cmanuelma@ ciudad.com.ar
M2 Isabel Alonso Magdaleno
UNIVERSIDAD DE OVIEDO
Facultad de Ciencias Economicas y Empresariales
Avda. del Cristo, s/n
33071-Oviedo-Espana
Phone: +34 985 10 36 99
e-mail address: ialonso@ econo.uniovi.es
ABSTRACT
This research studies the physical, economic and financial results obtained by the
application of an array of technical methods on the beef production system under
grazing conditions generally applied in the “wet argentine pampa”. A simulation
model of a ranch was developed to represent the responses to the use of different
technological packages. Systems Dynamics is the tool employed in this study.
The Argentine beef production system under grazing conditions is integrated by two
subsystems: the first is the cow-calf operation and the second is the fattening of
calves after weaning. One of the most important figures of the first subsystem is the
variable which reflects the number of animals per unit of surface, or carrying
capacity. Carrying capacity, feedstuffs quality and ranch management practices — for
example: the employment of compensatory growth— are the most important aspects
of the second subsystem. The beef production system was simulated employing
these variables (carrying capacity, the quality of diet, compensatory growth) as
management tools. It also considered the economic and physical answers reached
by modifying them.
The response to changes of the variables above mentioned variables has been
observed on the economic result ($), return on capital (%), gross margin ($/Ha), beef
production (Kg/Ha) and forage requirements (cow equivalent/Ha). These results
confirm the figures mentioned in the bibliography of reference to this subject.
This study has done a sensibility analysis and a risk evaluation to measure the
economical support of the thesis. Also, it was useful to analyse different strategies in
the beef production system.
Economic re
,
Investments in
production
> Cost per unit z
} 5 Purchase of
animals for slaughtey
Field production e
capacity
+ Production
Availability for
= delivery
cepa —_ ar
Investment in aD
production capital_- Finished
———animals
DESIGN OF THE MODELO
Product
delivery
Environment
Animal
Production
BIOLOGICAL COMPONENTS IN GRAZING SYSTEMS
DESIGN OF THE MODEL
Grazing
bs = animal
: Product
a
y On
oe Live forage Sie & silage
Radiation ——»> Growth
Conservation
Dead Soil, water
material & minerals
Mineralization ony
evaporation &
Runaway water
Botanical composition
: - Soil seed bank sé is)
Seed production Germination &
competence
FLUX DIAGRAMS : BIOLOGICAL COMPONENTS
a WW. Available
~ forage
>
- Growth ratg
Reproductive state
Climatic data
Soil moisture
(>
Harvest rate
Evapotranspiration
& drainage
DESIGN OF THE MODEL
Animal
factors
Size a,
Production
level
Type
pe! Potential p| Real daily Ss
daily intake intake
Environment~—Climate
Pasture attributes— Structure
A
t availability Payne
Supplementary
feeding
Physical = ity «____ Sensory
properties puallty factors
Chemical —f Water
composition content
Anti quality
substances
FLUX DIAGRAM: INTAKE OF THE GRAZING
ANIMAL
DESIGN OF THE MODEL
Fem calves
sold
F em calves for sale
Female calves
Heifers
Fem calves weaned
Replacement calves
Replacement heifers Percentage of calves weaned
Months of growth to servicie
v Male calves
sold
Male calves weaned
Replacement
heifers
= Cow replacement total females on service
porcentage of non pregnant cows =
Pregnants ne
Lactating
DCs females bee
Pregnant cows
Cows didfarded )
week counter
Cows discarded a
{" fattening t
Fat cows
sold
FLUX DIAGRAMS: EVOLUTION OF HEAD COUNT IN A COW CALF OPERATION
NE prod.
Individual
growth
NEp feed
Kg prod. +
Kg maint:
NEm feed
RESULTS OBTAINED
g 11:49 Al Thu, Feb 22, 2001 Table 17: p§ (Untitled Table) 2 3 =] a
Weeks Ti Intake |}2/ Intake |}3) Intake |}4) Intake ]§} Intake 6} Intake ]]7} Intake [§ Intake [9 Intake |{f) Intake iva
0000 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00
4.0000 6.49 6.54 6.58 6.62 6.66 6.70 6.73 677 6.80 6.84
8.0000 7.00 7.09 A? 7.26 7,32 7.40 7H 7.83 7.60 77
12.0000) 7.62 7.64 7.76 7.88 7.99 $.09 8.20 8.30 8.39 $.48
16.0000) 8.04 8.21 8.36 8.51 8.66 8.79 8.93 9.06 9.18 9.30
20,0000 8.58 8.78 8.97 9.16 9.33 9.50 9.66 9.81 9.96 10.10
24.0000) 9.12 9.36 9.58 9.80 10.00 10.20 10.39 10.57 10.74 10.91
28,0000) 9.64 9.92 10.18 10.43 10.66 10.89 11.10 W131 11.51 11.70
32.0000) 10.18 10.49 10.79 11.06 11.33 11.88 11.82 12.06 12.27 12.49
36.0000 10.73 11.08 11.40 Wi 12.00 12.28 12.54} 12.80 13.04 13.28
40.0000) 11.31 11.69 12.04) 12.37 12.69 12.99 13.28 13.56 13.82 14.08
44,0000) 11.90 12.31 12.69 13.05 13.39 13.72 14.03 14.33 14.61 14.89
48.0000 12.61 12.94 13.38 13.74 14.10 14.48 14.78 16.10 16.40 16.70
Final 13.12 13.59 14.02 14.8 14.82 16.18 16.54} 16.87 16.20 ain
r
VARIATION IN GRAZING VOLUNTARY INTAKE
RESULTS OBTAINED
@ 11:49 At Thu, Feb 22, 2001 Table 17: p2 (Untitled Table) 2? faa
Weeks Ii LWDG] |2/LWDG] |3/LWDG| |4/LWDG] |§LWDG] |6)/LWDG} |?7}LWDG] |8)/LWDG] |§|LWDG| |i} LWDG na
0000 0.58 0.63 0.69 0.74 0.78 0.83 0.88 0.92 0.96 1.01
4.0000) 0.60 0.65 0.70 0.74 0.79 0.83 0.8? 0.91 0.95 0.99
8.0000) 0.61 0.86 0.70 0.75 0.79 0.83 0.87 0.91 0.94 0.98
12.0000 0.62 0.67 o7 0.76 0.79 0.83 0.87 0.90 0.94 0.97
16.0000 0.63 0.68 0.72 0.76 0.80 0.83 0.87 0.90 0.93 0.96
20,0000 0.64 0.69 073 O77 0.80 0.84 0.8? 0,90 0.93 0.96
24.0000 0.62 0.66 o7 0.75 0.78 0.82 0.86 0.88 0.91 0.94
28,0000) 0.64 0.68 0.72 0.76 0.79 0.82 0.86 0.88 0.91 0.94
32.0000 0.65 0.69 0.73 0.76 0.80 0.83 0.86 0.89 0.92 0.94
36.0000 0.68 o7 0.76 0.78 0.81 0.84 0.87 0.90 0.93 0.95
40.0000 0.70 0.74 O77 0.80 0.83 0.86 0.89 0.91 0.94 0.96
44.0000 o7 0.75 0.78 0.81 0.84) 0.87 0.89 0.92 0.94 0.96
48.0000) 0.73 0.76 0.79 0.82 0.85 0.87 0.90 0.92 0.94 0.96
Final 0.74 O77 0.80 0.83 0.86 0.88 0.90 0.92 0.95
LIVE WEIGHT DAILY GAIN (LWDG) VARIATION
RESULTS OBTAINED
@ 1140.44 Thu, Feb 72, 2001 Table 17: p1 (Untitled Table) ? >
Weeks ~ i ivewelght] 7 [Livewelght]» [Liveweight|q [Live weight] 5 [Live weight] g [Live weight] > [Live weight] g [ive weight] [Live weight] 4p [Live weight
‘o000] 20000] 200.00] 20000] 200.00] 20000] 200.00] 20000 200.00] 20000] 200.00
4.0000 216.45 217.92 219.33 220.69 222.00 223.26 224.49 225.68 226.83 227.96
§.0000' 233.33 236.20 238.94 241.57 244.10 246.53 248.99 251.17 253.37 256.52
2.0000 26086) 26477| 26078] 262.61 20620) 260.03 avaaa4l 270.63| a7a72| —2en.e1
16.0000 26806) 273.68| areat| 289.79| 20866] 200.14| 207.66] 201.00] aosai| 200.00
20,0000 285.91 292.66 299.05 305.13 310.95 316.52 321.87 327.03 332.01 336.82
24.0000 303.98 311.93 319.46 326.59 333.40 339.93 346.18 362.20 358.01 363.62
70.0000) 2210] sanee| 30.04] 947.60 366.98| 902.80] 70.02 areai| 60.64] ga0.04
32.0000 339.43 349.79 369.56 368.79 377.58 386.96 393.99 401.70 409.12 416.28
36.0000 357.80 369.30 380.11 390.33 400.03 409.28 418.14) 426.63 494.80 442.68
40.0000 376.96 389.51 401.30 412.44 423.00 $33.07 442.69 461.92 460.79 469.36
40000] 306.77| aioe] 420.08] 42605 440.42| 467.26 aer.ei| arzsal 47.08] 4026
48.0000 416.95 8146 446.07 467.90 470.05 481.62 492.67 $03.26 613.43 $23.23
Final P74 462.86 467.32 480.95 493.86 $06.14 $17.86 §29.09 $39.88 $60.27
‘|_|
LIVE WEIGHT VARIATION
RESULTS OBTAINED
@ 11:49 At Thu, Feb 22, 2001 Table 17: p4 (Untitled Table) v4 é = a
Weeks if ENm racion|2: ENm racion} 3: ENm racion| 4: ENm racion| 6: ENm racion| 6: ENm racion| 7: ENm racion}8: ENm racion| 9: ENm racion| 10: ENm aaall s
0000 1.42 1.60 1.59 1,67 1,76 1.84 1.93 2.02 2.10 2.19
4.0000 1.42 1.49 1.57 1,65 1.72 1.80 1.87 1.95 2.02 2.09
8.0000 1.41 1.48 1.56 1.63 1.69 1.76 1.83 1.89 1.96 2.02
12.0000 141 1.48 1.54 1.61 1.67 1.73 1.79 1.85 1.90 1.96
16.0000 1.41 1.47 1.53 1.69 1.65 1.70 1.75 181 1.86 1.91
20,0000} 141 1.46 1,52 1.58 1.63 1.68 1.73 1.78 1.82 1.87
24.0000) 1.34 1.40 1.4% 1.61 1,56 1.61 1.66 1.70 1.75 1.79
28,0000) 1.36 1.40 1.45 1.60 1.55 1.60 1.64 1.69 1.73 1.77
32.0000 1.36 1.40 1.46 1.50 1.54 1.59 1.63 1.67 Ww 174)
36.0000} 1.38 1.43 1.48 1.62 1.56 1.60 1.64 1.67 171 1.74
40.0000 141 1.46 1.50 1,53 157 1.61 1.64 1.68 Wi 1.74)
44,0000) 1.41 1.46 1.49 1.53 1.57 1.60 1.63 1.66 1.69 1.72
48.0000 1.42 145 1.49 1.53 1.56 1.59 1.62 1.66 1.68 1,70
Final 1.42 1.4 1,49 1.62 1.55 1.68 1.61 1.64 1.66 1,69 we
‘|| in
VARIATION OF ENERGETIC CONCENTRATION IN THE DIET (Net energy for maintenance)
RESULTS OBTAINED
g 11:49 At Thu, Feb 22, 2001 Table 17: p3 (Untitled Table) ? é =] a
Weeks 1: ENp racion |2: ENp racion |3: ENp racion |4: ENp racion |: ENp racion |6: ENp racion |7: ENp racion |8: ENp racion |9: ENp racion | 10: ENp raciony |“
0000 0.92 0.99 1.06 1.14 1.21 1.28 1.36 1.43 1.50 1.68
4.0000 0.92 0.98 1.06 111 1.18 1.24 131 1.37 1.4 1.50
8.0000 0.91 0.98 1.04) 1.10 1.16 1.21 1.27 1.32 1.38 1.48
12.0000) 0.91 0.97 1.02 1.08 1.13 1.18 1.23 1.28 1.33 1.38
16.0000) 0.91 0.96 1.01 1.06 1 1.16 1.21 1,25 1.29 1.34)
20.0000 0.91 0.96 1.01 1.06 1.10 1.14 1.18 1.22 1.26 1.30
24.0000 0.87 0.92 0.97 1.01 1.06 1.10 1.14 1.18 1.21 1,26
28.0000 0.87 0.92 0.96 1.01 1,06 1.08 1.12 1.16 1.19 1.23
32.0000 0.88 0.92 0.96 1.00 1.04 1.07 141 1.14 1.18 1.21
36.0000 0.89 0.93 0.97 1.01 1.04 1.08 1 1.14 1A? 1.20
40.0000 0.91 0.95 0.98 1.02 1.06 1.08 11 1.14 1A? 1.19
44,0000 0.91 0.95 0.98 1.01 1,04 1.07 1.10 1.13 116 1.18
48.0000 0.92 0.95 0.98 1.01 1.04 1.07 1.09 1.12 1.14 1.16
Final 0.92 0.96 0.98 1.01 1,03 1.06 1.08 1.41 1.43 1.16 ce
‘| Ma
VARIATION OF ENERGETIC CONCENTRATION OF THE DIET (Net energy for weight gain)
T 1
41.60 $2.00
3:25 PM Thu, Feb 22, 2001
RESULTS OBTAINED
Beef gross margin increase
250000.00—
T 1
41.60 52.00
3:25 PM Thu, Feb 22, 2001
BEEF GROSS MARGIN VARIATION AS CORN SUPPLEMENTATION INCREASE
RESULTS OBTAINED
@ 12:08 Pot Thu, Feb 22, 2001
Table 17: p6 (Untitled Table) fa
Weeks {-|Cow Eq Cany capacity | |9.|Cow Eq Cany capacity | |g. {Cow Eq Cany capacity | | 4-|Cow Eq Camry capacity | |§|Cow Eq Camry capacity
ooo] =S*«*«*«w 389.94 197.94 132.94 192.94
4.0000 884.94 389.94 197.94 192.94 132.94
8.0000 682.44 438.69 248.89 185.44 165.44
12,0000 1,039.94 817.44 425.44 78481 78401
16.0000 1,089.44 618.19 474.19 317.11 37.11
20.0000 987.94 545.44 425.44 784.81 284.61
24,0000 930.44 605.44 605.44 497.11 219.61
28,0000 1,060.44 870.44 670.44 540.44 982.94
32,0000 1,157.94 719.19 719.19 872.94 195.44
36.0000 987.94 592.94 832.94 981.27 306.27
40.0000 903.89 544.32 952.32 238.86 236.86
44,0000 682.44 438.69 248.69 185.44 165.44
48.0000 617.44 406.19 214.19 14.77 143.77
Final 584.94 980.94 197.94 132.94 192.94
VARIATION OF HERD REQUIREMENTS AS SEASONS GROW UNFAVORABLE
RESULTS OBTAINED
@ 12:08 Pot Thu, Feb 22, 2001
Table 17: p? (Untitled Table) fa
Weeks {.| Cow Eq Requirements |] 9) Cow Eq Requirements | |3:| Cow Eq Requirements || 4] Cow Eq Requirements | | §| Cow Eq Requirements
0000 676.62 677.06 a7.74 a4 CTT
4.0000 713.18 713.80 502.30 502.32 502.32
8.0000 760.03 750.80 606.99 606.88 608.88
12.0000 787.02 787.84 665.63 621.52 621.52
16.0000 824.40 826.15 687.68 636.02 636.02
20.0000 862.35 869.13 7091.85 66041 66041
24.0000 292.60 889.83 810.79 791.34 664.63
28.0000 900.81 926.43 947 44 8270 679.06
32.0000 969.22 964.20 884.33 963.51 603.44
36.0000 1,012.29 1,008.71 927 02 906.12 707.77
4.0000 1,056.83 1,056.75 967.24 772.69 721.84
44.0000 1,098.12 1,098.41 803.18 788.34 735.61
48.0000 1,139.60 1,140.18 817.25 800.20 749.51
Final 1,181.40 1,182.23 831.40 814.15 763.47
VARIATION OF HERD REQUIREMENTS AS SEASONS GROW UNFAVORABLE
SYSTEMS DYNAMICS
BIBLIOGRAPHY
BIBLIOGRAPHY
