Introduction

This document explores the differences in total liveweight (LW) that can be expected from:

In the brazil_cattle_population.Rmd, we offers three options to infer annual LW per municipality:

  1. Using the IBGE Census of 2006 following MCTI (2020) - with and without dairy cows
  2. Using the Anualpec (2017) relative population ratio
  3. Using SIGSIF to associated slaughter to cattle end-of-life.

LW is also determine per region following MCTI (2020) and compared to values from Erasmus listed below:

Liveweight and population estimates from different methods

First, we take the total municipal cattle population per age group and derive the state total cattle LW. We use the MCTI LW for this exercise before comparing difference with LW estimates (further below).

The different estimates provide large differences in total LW in Brazil (for 2016):

The largest estimate is the standard estimate (current approach) and the lowest is the SIGSIF approach. There is a 500 Mtonne differences between the lowest and highest estimates. The Census and Anualpect approach lead to roughly the same LW estimate.

There are large differences with the SIGSIF approach, which makes me think that it is too low.

We can compare the head population only with the MCTI (2020) estimates

Compared the values of MCTI for 2016 which was 217492377

So the current methods is close to the MCTI total heads, but the combination of approaches (e.g. Census vs. Anualpec) can get the range of heads. We then need to compare the estimate of enteric methane emissions.

Effects on enteric methane emission estimates

We then attribute the emissions factors to the cattle population age groups to derive the total state enteric methane emissions (focusing on 2016).

Lower entric methane emissions estimates

The lower enteric methane emission estimates were derived using lower emission factors that were calculated assuming that the animals do not need to travel far to get food (Ca = 0.17).

  • The MCTI approach using census data (no dairy cows): 10182.6 Gg CH4
  • The MCTI approach including the dairy cows: 11182.9 Gg CH4
  • The Anualpec approach including the dairy cows: 11310.2 Gg CH4
  • The SIGSIF approach: 8091 Gg CH4
  • The MCTI approach with dairy cows and using the LW from SEI-PCS v.1: 12665.8 Gg CH4

Compared the values of MCTI for 2016 which was 11350.5 Gg CH4.

Higher enteric methane emissions estimates

We then recalculate enteric methane emissions using the high emission factors with (Ca = 0.36). It seems that MCTI was using either or.

  • The MCTI approach using census data (no dairy cows): 11362 Gg CH4
  • The MCTI approach including the dairy cows: 12477.9 Gg CH4
  • The Anualpec approach including the dairy cows: 12634.1 Gg CH4
  • The SIGSIF approach: 8974.3 Gg CH4
  • The MCTI approach with dairy cows and using the LW from SEI-PCS v.1: 14427.1 Gg CH4

Compared the values of MCTI for 2016 which was 11350.5 Gg CH4.

Emissions per cattle category

We compare our results for category-specific emissions with MCTI using “high” and “low” emission factors

##                                            [,1]        
## YEAR                                       "2016"      
## CALF_1_BEEF_CENSUS_CH4                     "1494902780"
## CALF_1_2_BEEF_CENSUS_CH4                   "2547031368"
## ADULT_2_BEEF_CENSUS_CONFINED_CH4           "260950308" 
## VACAS_2_BEEF_CENSUS_UNCONFINED_CH4         "2895271228"
## BOIS_2_BEEF_CENSUS_UNCONFINED_CH4          "2817436624"
## TOUROS_2_BEEF_CENSUS_CH4                   "166959420" 
## CALF_1_BEEF_DAIRY_CENSUS_CH4               "1647519755"
## CALF_1_2_BEEF_DAIRY_CENSUS_CH4             "2807104793"
## ADULT_2_BEEF_DAIRY_CENSUS_CONFINED_CH4     "274628580" 
## VACAS_2_BEEF_DAIRY_CENSUS_UNCONFINED_CH4   "3105170116"
## BOIS_2_BEEF_DAIRY_CENSUS_UNCONFINED_CH4    "3165891708"
## TOUROS_2_BEEF_DAIRY_CENSUS_CH4             "182549220" 
## CALF_1_BEEF_DAIRY_ANUALPEC_CH4             "1958111120"
## CALF_1_2_BEEF_DAIRY_ANUALPEC_CH4           "2207884360"
## ADULT_2_BEEF_DAIRY_ANUALPEC_CONFINED_CH4   "293893473" 
## VACAS_2_BEEF_DAIRY_ANUALPEC_UNCONFINED_CH4 "3181880258"
## BOIS_2_BEEF_DAIRY_ANUALPEC_UNCONFINED_CH4  "3567013631"
## TOUROS_2_BEEF_DAIRY_ANUALPEC_CH4           "101443740" 
## CALF_1_BEEF_SIGSIF_CH4                     "219940"    
## CALF_1_2_BEEF_SIGSIF_CH4                   "6196626085"
## VACAS_2_BEEF_SIGSIF_CONFINED_CH4           "15829953"  
## BOIS_2_BEEF_SIGSIF_CONFINED_CH4            "40394070"  
## VACAS_2_BEEF_SIGSIF_UNCONFINED_CH4         "606695589" 
## BOIS_2_BEEF_SIGSIF_UNCONFINED_CH4          "1231244506"

We compare the above results with those published for 2016 by MCTI(2016)

Bulls (> 2 y):

  • 167.0 Gg from Census (no dairy cows)
  • 182.5 Gg from Census (with dairy)
  • 101.4 Gg from Anualpec (with dairy)
  • 410.9 Gg from MCTI (2020)

Males (> 2 y, unconfined):

  • 2817.4 Gg from Census (no dairy cows)
  • 3166 Gg from Census (with dairy)
  • 3567 Gg from Anualpec (with dairy)
  • 40.4 Gg from SIGSIF
  • 2552.4 Gg from MCTI (2020)

Females (> 2 y, unconfined):

  • 2895.3 Gg from Census (no dairy cows)
  • 3105.2 Gg from Census (with dairy)
  • 3182 Gg from Anualpec (with dairy)
  • 607 Gg from SIGSIF
  • 3467.8 Gg from MCTI (2020)

Adults (>2 y, confined):

  • 261 Gg from Census (no dairy cows)
  • 275 Gg from Census (with dairy)
  • 294 Gg from Anualpec (with dairy)
  • 56 Gg from SIGSIF
  • 249.4 Gg from MCTI (2020)

Calves (< 1 y)

  • 1494.9 Gg from Census (no dairy cows)
  • 1647.5 Gg from Census (with dairy)
  • 1958.1 Gg from Anualpec (with dairy)
  • No estimate from SIGSIF (since same as Anualpec)
  • 1635.7 Gg from MCTI (2020)

Calves (1-2 y):

  • 2547 Gg from Census (no dairy cows)
  • 2807 Gg from Census (with dairy)
  • 2208 Gg from Anualpec (with dairy)
  • 6197 Gg from SIGSIF
  • 3034.3 Gg from MCTI (2020)

So this shows that the MCTI procedure has been well applied and our numbers are robust at the country and category level (right range). We should ditch the SIGSIF approach as the results are too low compared to MCTI, a mix of Census (without dairy) and Anualpec (with dairy).

Reference

Link to the MCTI report: MCTI report