“Rotatinuous” grazing: Management targets, efficiency of pasture utilization, and enteric

methane emissions by dairy cattle

Alejandra  Marín,  Zoot.  MSc.  PhD  (e)      

Climate  Food  and  Farming  Network  (CLIFF)  Workshop  2017  7-­‐11  November,  2017  

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Content

Introduction

Background

Methods

Results and conclusions

Conceptual model

Application of this research

Acknowledgement

My PhD thesis focuses on the sustainable intensification of forage-based systems, improved animal production and feed efficiency, and on strategies to mitigate enteric methane emissions by dairy cattle.

The goal of the research is to define grazing management targets to optimize nutrient consumption per unit of time and increase pasture utilization efficiency.

Improving grazing management is an effective approach for increasing animal productivity and reducing GHG emissions intensity (particularly CH4) per unit of animal product or per area.  

Introduction

Research focus

Management targets are plant oriented and focus on harvesting efficiency

Rotational stocking

Herbage quality and quantity would be the main constraint to animal production on pasture systems

From this perspective...

Background

Pre-­‐Grazing   Post-­‐Grazing  

Best  harvest  @me  .  .  .  Herbage  mass  +  +  +   Best  @me  to  leave.  .  .  Herbage  mass    -­‐  -­‐  -­‐      

Savian,  2014  Savian,  2014  

“Rotatinuous grazing”

is based on the principle…:

…“take the best and leave the rest”… from the pasture.

(Carvalho, 2013)

Rotatinuous concept is an innovation in grazing management based on the ingestive behaviour.

The “Rotatinuous" grazing concept

We  are  including  the  “animal  perspec@ve”    

Hypothesis: the main constraint is SWARD STRUCTURE . . . the consequence is time restriction.

Sward structure è maximizes bite mass.

SWARD STRUCTURE(Pre and post- grazing

sward heights)

Bite mass

Estructures that optimize bite mass

Maximize bite mass and forage intakeper unit grazing time

FORAGE USE EFFICIENCY

MORPHOLOGICAL COMPONENTSLeaf mass, leaf/stem ratio.

Herbage bulk density.

QUALITY OF FORAGENDF, NDA, CP,IVDMI, Energy

Herbage accumulation rate

Herbage mass

Total herbage production

NO TIME

ANIMAL PRODUCTIVITY

Bite rate

SHORT-TERM INTAKE RATE(STIR)

DAILY HERBAGE INTAKE

Average daily gain

VFA (C2, C3, C4)

ENTERIC METHANE EMISSIONS

ENTERIC CH4 EMISSION INTENSITY(CH4/unit animal product or area)

Intake of nutrientsGRAZING TIME*

Conceptual model

Phase I

Phase II PredicFon   of   the   nutriFonal   composiFon  of  the  Kikuyu  by  near-­‐infrared  reflectance  spectroscopy  (NIR).  

Effect  of  sward  surface  height  (SSH)  on  in  vitro   methane   producFon   and   ruminal  fermentaFon  parameters  of  caOle  grazing  kikuyu  swards  -­‐  (IVGPT)  

Advances . . . Phase I

Effect of sward surface height on STIR of heifers grazing in kikuyu swards

Hypothesis:

There is an optimal pre-grazing sward height, which maximize the short-term herbage intake rate (STIR) by the animals.

Objective:

Evaluate the effect of the kikuyu sward height on STIR and determine the sward structure (pre-grazing) that maximizes bite mass and herbage intake.

Phase I

The central hypothesis of phase I is…  

Phase I: Effect of sward surface height on STIR of heifers grazing in kikuyu swards

STIR= [(W2-W1)/(t2-t1)] + [(W3-W4)/(t4-t3)] x (t2-t1)/ET

Where: STIR: short-term herbage intake rate (g/min) W1 and w2: animal’s weight pre- and post-grazing (kg) t1 and t2: pre- and post-grazing time (min) W3 and W4: animal’s weight pre- and post- metabolic weight losses(kg) t3 and t4: pre- and post-metabolic weight losses time (min) ET: Effective eating time

Intake of forage Metabolic weight losses

Pennings  and  Hooper,  1985    

Methods

The STIR could be measured by accurately weighing animals before and after a grazing bout and making adjustment for metabolic weight loss and precise recording of eating time.

Experimental unit: Plot

Sampling units : Animal

Metabolic weight losses

IGER Feces and urine collecting bags

ü  Treatments: Kikuyu sward heights: 10, 15, 20, 25, and 30 cm.

ü  Size of the plots (500 m2): Scaled so that average sward height declined less than 5% over the grazing sessions.

ü  Statistical design: A complete randomized block 4 replicates x treatment. ( two per area and two per time of the day (am or pm as blocking criterion).

ü  Each experimental plot (20) was grazed by three animals during a single grazing session of 45 ± 5 min.

ü  The experiment was carried out in Lages, Santa Catarina-Brazil between January and May, 2017.

Treatments and design Methods

Preliminary results

RelaFonships   between   short-­‐term   intake   rate   (STIR,   a)   of   heifers   as   a   funcFon   of  sward  height  (SH)  in  monoculture  of  Kikuyu  (Cenchrus  clandes-nus  (Hochst.  ex  Chiov.)  

Results and conclusion

The resu l t s showed tha t maximization of STIR of kikuyu grass is reached at sward height 20 cm. These findings indicate that the animals maintain a high and continuous intake rate in that sward structure. Later this begins to fall progressively.

STIR  (gDM

/min)  

20            

30            

40            

50            

60            

10             15             20             25             30            

Sward  height  (cm)  

EquaFons  for:  STIR=min((44.14  +  1.31  x  (SH  –  19.71);  44.14  –  0.45  x  (SH  –  19,71))    

Marín  et  al,  2017-­‐  h^ps://www.researchgate.net/publica@on/319598924_The_intake_rate_a_strategy_for_the_sustainable_grazing_management    

Conclusions Results and conclusion

Based on this expectancy, we propose a new management target for Colombian dairy cattle systems based on kikuyu grass (pre-grazing height: 20 cm) to comply with its sustainable livestock farming policy commitments.

Next step . . . Phase II

The phase II will be carried out in Medellín, Colombia / 2018

Effect of “rotatinuous” grazing on efficiency of pasture utilization, and enteric methane

emissions by dairy cattle

 Colombia

Medellín

Methods

Phase II: Efficiency of pasture utilization, and enteric methane emissions by dairy cattle

South America

Specialized cattle production systems is located in the Andean region. It is characterized by pasture-based dairying with high grade Holstein cattle. It is generally based on strip grazed or rotationally grazed Kikuyu grass and supplement (30%).

Hypothesis:

By maximizing the intake of herbage per unit eating time, “rotatinuous” grazing improves the efficiency of pasture utilization and reduces enteric methane emissions.

Objective:

Evaluate the effect of a new pasture management concept “rotatinuous” grazing on kikuyu grass pasture use efficiency and enteric methane emissions intensity from dairy cattle in rotational stocking.

Phase II

SF6  tracer  technique  

CLIFF 2017

Scientific training at CIAT. . . Colombia

Training in  near-infrared reflectance spectroscopy (NIR).

1 Sample collection

2 Analysis by the reference method

3 NIR spectral analysis

4 Data interpretation (calibration and validation)

Objective: Prediction of the nutritional composition of kikuyu by near-infrared reflectance spectroscopy (NIR).

Development of the in vitro gas production technique (IVGPT)

Objective: Determine the effect of different kikuyu grass sward surface heights on in vitro methane production, and also on the main ruminal fermentation parameters (gas production, pH, in vitro dry matter digestibility (IVDMD), CH4, and volatile fatty acid (VFA) concentration.

0,0  

5,0  

10,0  

15,0  

20,0  

25,0  

30,0  

35,0  

40,0  

45,0  

50,0  

0   5   10   15   20   25   30   35   40   45   50  

Volume  of  gas  (m

l)  

OMI  (g)  

Accumulated  gas  produc@on  ml/g  OMI  

Sward  height  10  cm   Sward  height    15  cm   Sward  height    20  cm   Sward  height    25  cm   Swardheight    30  cm  

We hypothesize the optimal pre-grazing sward height (20 cm) may result in high dry matter digestibility (IVDMI) and less in vitro methane production.  

Application of this research

This information introduce a new grazing management target in Colombia, based

on the influence of sward structure on herbage intake, which will allow to have

sustainable farm system and greater productivity and consequently less impact of

the enteric methane emissions generated by livestock.

Our goal is to take this knowledge to Colombia to generate solutions in

agricultural production systems and improving smallholder dairy.

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Rotatinuous grazing is a grazing management concept based on animal behavior

that contributes to food security by enhancing production and quality of food

products, while mitigating impacts of grazing ruminants by decreasing GHG

emissions and external inputs needs.

Rotatinuous grazing represents a technological innovation based on concepts,

not on inputs.

Smallholder appreciate this grazing management because it results in lower

dependence on external inputs and lower labor requirements.

Key messages

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Acknowledgements

This work was undertaken as part of the Climate, Food and Farming (CLIFF) Network, an initiative of the CGIAR Research Program on Climate Change, Agriculture and Food

Security (CCAFS). CCAFS is carried out with support from CGIAR Fund Donors and

through bilateral funding agreements.

We thank COLCIENCIAS for their support through COLCIENCIAS Scholarship Program No.

647, as well as the National University of Colombia and the Federal University of Rio

Grande do Sul for facilitating their respective research facilities.

We gratefully acknowledge the generous support we have received from EPAGRI by the

CNPq, MDA/CNPq Edital 38/2014 (Proceso CNPq 472977/2014-8).

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Thanks

Alejandra Marín amaring@unal.edu.co