How high is herbage intake of organic rabbits grazing fescue or sainfoin?

H. Legendre¹, J.P. Goby², J. Le Stum², G. Martin³ and T. Gidenne¹

¹INRA, GenPhySE, Université de Toulouse, 31326 Castanet Tolosan, France, ²Université de Perpignan, IUT, 66962

Perpignan, France, ³INRA, AGIR, 31326 Castanet Tolosan, France; heloise.legendre@inra.fr

Little is known about herbage intake of grazing rabbits. We determined herbage intake and pasture utilization of rabbits fattened under organic production standards. During spring 2016, 30 rabbits were raised for 9 weeks in rolling cages (3 rab. per cage with 0.4 m² of grazing area per rabbit, the minimum rate specified by the organic standards) from weaning at 43 days of age. 5 cages were moved on a pure stand of tall fescue (Festuca arundinacea, F), and 5 cages on a grassland dominated by sainfoin (Onobrychis viciifolia, S). Cages were moved every day, and rabbits were supplemented with 60 g/d/rab. (52.5 g dry matter, ‘DM’) of a complete pelleted feed (no refusal). Once a week, herbage samples were collected at two locations (0.25 m² each) for each cage: on the side of the cage to measure herbage allowance, and on the line of the cage, just after moving it to measure grazing refusals. Herbage intake was estimated as the difference between herbage allowance and refusals, and expressed per kg of metabolic weight (kg0.75). Over the whole grazing period, herbage allowance was higher in S than in F (5.1 ton DM/ha or 120.1 g DM/kg0.75 vs 2.2 ton DM/ha or 59.5 g DM/kg0.75, P<0.01), and herbage intake (59.2 g DM/kg0.75 vs 37.3 g DM/kg0.75, P<0.01) accounted for respectively 47% and 65% of the allowance. During the first grazing week, rabbits displayed limited herbage intake (resp. 15.8 and 7.8 g DM/kg0.75 for S and F, P=0.39) and utilization (16% and 20%). Thereafter, herbage intake increased and the maximum was reached on week 9 for S rabbits (112.3 g DM/kg0.75 or 947.5 g of fresh matter/2.5 kg rab., 70% of the allowance), and on week 5 for F rabbits (51.2 g DM/kg0.75, 60% of the allowance). Herbage allowance in F dropped during the last 4 weeks (46.8 g DM/kg0.75) yielding lower intake (35.3 g DM/kg0.75) but enhanced utilization, i.e. 77% in average, and up to 93% in week 6. In conclusion, rabbits develop a high herbage intake capacity during fattening (up to 40% of their bodyweight). When herbage biomass is too low (i.e. below 85 g DM/kg0.75), stocking rate per cage must be adjusted in order to increase herbage allowance per rabbit.
# How high is herbage intake of organic rabbits grazing fescue or sainfoin ?

Heloise Legendre, Jean-Pierre Goby, Jean Le Stum, Guillaume Martin, Thierry Gidenne

► To cite this version:

Heloise Legendre, Jean-Pierre Goby, Jean Le Stum, Guillaume Martin, Thierry Gidenne. How high is herbage intake of organic rabbits grazing fescue or sainfoin?. 68. Annual Meeting of the European Federation of Animal Science (EAAP), Aug 2017, Tallinn, Estonia. hal-01604550

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Submitted on 2 Jun 2020

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IUT
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# How high is herbage intake of organic rabbits grazing fescue or sainfoin ?

Legendre H.<fnref n="1" />, Goby J.P.<fnref n="2" />, Le Stum J.<fnref n="2" />
Martin G.<fnref n="3" />, Gidenne T.<fnref n="1" />

<footnote n="1">¹GenPhySE, Université de Toulouse, INRA, 31326 Castanet Tolosan, France.</footnote>

<footnote n="2">²Université de Perpignan, IUT, 66962 Perpignan, France</footnote>

<footnote n="3">³INRA, UMR 1248 AGIR, 31326 Castanet Tolosan, France.</footnote>
# Organic rabbit breeding

Conventional

<figure><img src="image_7.png" /><figcaption>Photo Lebas F.</figcaption></figure>

Organic

<figure><img src="image_8.png" /><figcaption>Photo Gidenne T.</figcaption></figure>

Grazing management

Lack of knowledge on herbage intake / nutrition

Roinsard et al (2016)

Potential production unknown

Most relevant management practices yet to be defined (herbage allowance, stocking rate, regrowth)
# The moving cages

<figure><img src="image_9.png" /></figure>

Sheltered part

<figure><img src="image_10.png" /></figure>

Grazing access 0.4m²/rabbit/day
Experiment

At weaning (43 days of age)

3 rabbits/cage

5 cages

<figure><img src="image_11.png" /></figure>

3 rabbits/cage

5 cages

<figure><img src="image_12.png" /><figcaption>Pasture dominated by sainfoin</figcaption></figure>

<figure><img src="image_13.png" /></figure>

<figure><img src="image_14.png" /></figure>

+ 60g/day/rabbit
# Herbage intake measurements

<figure><img src="image_15.png" /><figcaption>Photo Legendre H.</figcaption></figure>

Manual shear
to cut at 3 cm

* Weakly;

* Herbage samples at 2 locations per cage :

- On the side of the cage = Herbage allowance,

- Within the cage (after moving the cage) = Herbage refusals,

- 0.25m² per location;

* Determination of dry matter DM (48h-60°C).
# Definitions

$$ 
\begin{gathered}
\text{Herbage Intake} = \text{Herbage allowance} - \text{Herbage refusals} \\
\text{HI} = \text{HA} - \text{HR}, \\
\text{expressed per kg of metabolic weight (kg}^{0.75})
\end{gathered}
$$

$$ 
\begin{gathered}
\text{Pasture utilization} = \text{Herbage Intake}/\text{Herbage Allowance} \\
\text{Pasture utilization} = \text{HI} / \text{HA}, \\
\text{expressed in \%}
\end{gathered}
$$
# Results

During 1st week of grazing
(43-50 days of age)

<table><thead><tr><td>Pasture</td><td>Sainfoin</td><td>Tall Fescue</td><td>P Value</td></tr></thead><tbody><tr><td>Herbage Intake g DM/kg<sup>0.75</sup></td><td>16</td><td>8</td><td>0.39</td></tr><tr><td>Pasture utilization %</td><td>16</td><td>20</td><td>0.8</td></tr></tbody></table>

Limited HI on both pastures (HA being sufficient to cover rabbit feed requirements)
# Results

Over the whole grazing period
(43-100 days of age)

<table><thead><tr><td>Pasture</td><td>Sainfoin</td><td>Tall Fescue</td><td>P Value</td></tr></thead><tbody><tr><td>Herbage Biomass t DM/ha</td><td>5,1</td><td>2,2</td><td></td></tr><tr><td>Herbage Allowance g DM/kg<sup>0.75</sup></td><td>120</td><td>60</td><td>&lt; 0.01</td></tr><tr><td>Herbage Intake g DM/kg<sup>0.75</sup></td><td>59</td><td>37</td><td>&lt; 0.01</td></tr><tr><td>Pasture utilization %</td><td>47</td><td>65</td><td>0.72</td></tr></tbody></table>

* HA : Sainfoin > Fescue (+100%)

* HI : Sainfoin > Fescue (+60%)

* Pasture utilization ≠ NS
# Results

## At the maximum

<table><thead><tr><th>Pasture</th><th>Sainfoin</th><th>Tall Fescue</th></tr></thead><tbody><tr><td>Week</td><td>9</td><td>5</td></tr><tr><td>Herbage Intake<br>g DM/kg<sup>0.75</sup></td><td>112</td><td>51</td></tr><tr><td>Pasture utilization<br>%</td><td>70</td><td>60</td></tr><tr><td>Herbage intake<br>g fresh matter (FM)</td><td>975</td><td></td></tr><tr><td>FM intake/Live weight<br>%</td><td>39</td><td></td></tr></tbody></table>

* **Sainfoin :**
  *Max HI end of the experiment*

* **Fescue :**
  * - 54% HI
  * Max week 5, but HA was low afterwards
*Fescue : HA dropped and remained low over the last 4 weeks*

g DM/kg 0.75

<figure><img src="image_16.png" /></figure>

Days since weaning
# Results With Low Herbage Allowance

<table><thead><tr><th>Pasture</th><th>Tall Fescue<br>MAX</th><th>Tall Fescue<br>Last 4 weeks</th></tr></thead><tbody><tr><td>Week</td><td>5</td><td><strong>6-9</strong></td></tr><tr><td>Herbage allowance<br>g DM/kg<sup>0,75</sup></td><td>85</td><td><strong>47</strong></td></tr><tr><td>Herbage Intake<br>g DM/kg<sup>0.75</sup></td><td>51</td><td><strong>35</strong></td></tr><tr><td>Pasture utilization<br>%</td><td>60</td><td><strong>77%</strong><br><strong>93% in week 6</strong></td></tr></tbody></table>
# Conclusion

MAX Pasture utilization= **93%**

<figure><img src="image_17.png" /><figcaption>Photo Legendre H.</figcaption></figure>

$$ 
\begin{aligned}
\text{MAX Herbage Intake} \\
&= 110 \text{ g DM/kg}^{0.75} \\
&= 40\% \text{ Live weight}
\end{aligned}
 $$

<figure><img src="image_18.png" /><figcaption>Photo Duprat A.</figcaption></figure>

A reduction of herbage allowance quickly results in a restriction of herbage intake

<figure><img src="image_19.png" /></figure>
Conclusion

<figure><img src="image_20.png" /><figcaption>Photo Gidenne T.</figcaption></figure>

* When herbage allowance < 85 g DM/kg⁰.⁷⁵ stocking rate must be adjusted :

– Greater grazing area,

– Less animals in one cage.

* More trials to confirm these values are needed
Thank you for your attention

<figure><img src="image_21.png" /></figure>

Acknowledgements

Financial support from INRA division PHASE (MarkPast project) + INRA AgriBio4 (CuniPat project) + GISA metaprogram of INRA (PROF project)

The authors thank the AVEM association for providing organic sainfoin's seeds, and all of the colleagues involved in data collection and analysis