Small Ruminant Research

ELSEVIER Small Ruminant Research 16 (1995) 27-35

Direct observation of biting for studying grazing behavior of goats and llamas on garrigue rangelands

B. Dumont *, a, M. Mew-et b, M. Prudhon a a ENSA-INRA, Chaire de Zootechnie. 9 place Viala, 34060 Montpellier Gdex I. France

b INRA-SAD, lJnitedEcod&loppement, Domaine Saint-Paul, 84143 Montfavet C&dex, France

Accepted 20 April 1994

Abstract

In any heterogeneous environment, classical methods used to estimate daily DMI and daily diets of grazing animals are difficult to implement. To investigate the grazing behavior of a goat and a llama, feeding on the garrigue in their respective flock, we therefore used a technique based on direct observation of biting. The observations were carried out in spring and early summer, and under decreasing vegetation availability conditions for each season. In high vegetation availability conditions, daily DMI at pasture was 44 g DM/kg Bw.75 (6th day in paddock: d6) and 76 g DM/kg Bw (d3) for the goat vs. 42 g DM/kg Bw75 (d3) and 53 g DM/kg BVf.75 (d3) for the llama during spring and summer, respectively. The goats diet (% DMI) was mainly composed of browse (89 to 99%)) whereas the llamas consisted of grass (55 to 78%). The choices made by the two animals were confirmed by the evolution of the consumption levels of the forage species in each paddock. As vegetation availability decreased, the daily DMI of the two animals fell and their requirements were no longer satisfied. In spite of shifts in daily diets, grass DM always accounted for at least 35% of the llamas diet but never exceeded this value for the goat. Diurnal variations were observed in the diets of both animals, which may reveal differences in grazing strategies: the goat seemed to be selective first, whereas the llama tried to eat quickly first. The morphological structure of browse species influenced instantaneous intake rates in the two animals. Because both animals occasionally focused on plant species that permit high intake rates, the curve of cumulative DMI within a meal vs. time bounced from time to time, and could not be adjusted to a mono-exponential model as with penned animals. The technique we used thus not only provides consistent data on the daily intake and daily diets of goats and llamas grazing a shrubby, heterogeneous environment but also information on the process of diet selection itself along the grazing journey.

Keywords: Mediterranean shrubland; Diet selection; Intake; Goat; Llama

1. Introduction

A garrigue is a type of vegetation community, mostly composed of Iow shrubs, that stretches on lime- stone over the Mediterranean countries. In southern

* Corresponding author at: INRA, Laboratoire Adaptation des Herbivores aux Milieux, Centre de Clermont-Fd/Theix, 63122 St Genes Champanelle, France.

France, garrigues are widely distributed: for example, in Languedoc-Roussillon region, they cover 300 000 ha (Thiault et al., 1979), more than 10% of the total area. They were intensively exploited during the last century, but as even sheep-farming itself has declined in the past 30 years, they are more and more covered with shrubs and thus sensitive to running fires. The garrigue now has a new host: the South American

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28 B. Dumont et al. /Small Ruminant Research 16 (1995) 27-35

llama. The species was recently introduced firstly, to reduce the risk of extensive fires and, secondly, to pro- duce high quality fibers and bring a complementary resource to lamb producers. A research program is now developed to compare the grazing behavior and animal performances of native sheep and goats and of llamas in garrigue areas.

In this heterogeneous environment, animals select their diet from various plant species and organs, differ- ing (or which differ) in digestibility, time spent in the digestive tract and potential internal marker content. It is difficult to measure diet digestibility and use markers such as chromic oxide or n-alkanes to estimate daily DMI. Another difficulty lies in the fact that feces bags and oesophagus fistulae are hard to use in the garrigue because of shrub density and of the morphological and behavioral traits of the animals. We therefore decided to adapt a direct observation technique to this environ- ment (Meuret et al., 1985; Meuret, 1989a), because it was supposed not only to give estimates of daily diet and daily intake level, but also detailed information on the process of diet selection itself all along the grazing journey.

We tested the technique by investigating the inges- tive behavior of a goat and a llama grazing in their respective flocks. The investigations were carried out continuously during daytime, in spring and in early summer, and under decreasing vegetation availability conditions for each season. In spite of intraspecies var- iations in grazing behavior, we obtained initial infor- mation about the ability of the two species to cope with coarse resources from garrigue rangelands.

2. Materials and methods

Vegetation Observations were made at an experimental location

near Montpellier (434 130 N, 34900 E) at an alti- tude of 130 m. Two experimental periods were defined: period 1 from mid-April to mid-May was the main growing season with rain (4 mm/d) and moderate average temperature ( 11C)) whereas, during period 2 in June, the growth stopped because of the already high temperature ( 18C) with little rain ( < 1 mm/d).

Four 0.4 to 0.6 ha paddocks were used. To estimate average cover, shrubs and grass patches were mapped and measured all along belt-transects (Etienne, 1989).

Six 0.5 X 20 m transects were used. The dominant shrub species were kermes oak (Quercus cocciferu), rose- mary (Rosmarinus ofSicinalis) , cade (Juniperus oxy- cedrus) and whin (Genista scorpius) , which covered 35, 15, 7 and 5% of the area, respectively. Patches of grasses (Brachypodium ramosum, Festuca ouina, Bro- mus erectus) covered around 25%. A few trees (Pinus halepensis, Quercus ibex) were also present.

Animals Two flocks (21 goats of local Rove breed and 11

llamas) lived all year round on this garrigue area. The flock of goats was composed of one male and 20 dry females, aged 1 to 7 years, the flock of llamas of two males, six castrated males and three dry females aged 1 to 6 years. Mean weights of the groups of goats and llamas were 41+9 and 88 &- 16 kg/animal, respec- tively. The goats had lived on Mediterranean range- lands (Quercus pubescens and Q. ilex coppices) since birth. All llamas were born in zoos but had been living on the garrigue for at least 1 year at the time of the study.

During each observation period, the two flocks were separately allocated to one of the four paddocks. They were placed sufficiently far apart so that neither could influence the grazing patterns of the other. Stocking densities were close to 2000 and 1600 kg BW/ha/d in spring and in early summer, respectively. The llamas were given a daily supplement of 250 g barley and minerals, while the goats received only minerals. Water and salt were available ad libitum.

The results concern the grazing behavior of one indi- vidual of each species; these individuals were selected after a 10-d preliminary period during which their abil- ity to accept the continuous presence of the observer was tested: indeed the observer continuously studied the animals during the 15 to 17-h daylight period and therefore had to follow them closely. The llama observed was a 3-year-old intact male weighing 111 kg, which had lived on the garrigue for 15 months. The goat was a 6-year-old, 52-kg BW dry female.

Measurements Potential edible matter (PEM) consists of the plant

parts the animals accept to consume in harsh pasturing conditions (Meuret, 1988). We first determined the PEMs for the main forage species during a preliminary period by observing the grazing behavior of both flocks,

B. Dumont et al. /Small Ruminant Research 16 (1995) 27-35 29

highly stocked. We then defined the consumption level (CL) of a shrub or a grass patch as the percentage of PEM consumed.

The day before each observation of the grazing behavior, 60 bushes from each of the three most fre- quent species (kermes oak, cade and rosemary) and 60 grass patches were randomly chosen within the pad- dock and put in classes according to their CL (Schmutz, 1983; Leouffre, 1991). We defined five classes: class 1 (0 to 5%), class 2 (5 to 25%), class 3 (25 to 75%), class 4 (75 to 95%) and class 5 (95 to 100%).

A CL index could then be defined daily for each species as:

+ (a,.O.SSO) + (a,.0.975)

with a, = % of i. The grazing behavior of the goat and llama was

recorded from dawn (about 90 min before sunrise) to dusk (at least 20 min after the animals had stopped grazing), but not during the night. It was also observed under decreasing vegetation availability conditions: d3 (or 6) and 19 in period 1; d3, 17 and 31 in period 2.

By closely observing the animals, we determined different types of bites which were later used as tools. Because of their great variety, the bites made on a given plant species were divided into classes of distinct struc- tural composition and mass (Meuret, 1989a,b). Since the animals did not seem to make any selection among mixed sward species, we defined the different types of bite according to differences in sward height, except for reproductive stems which formed a class apart. Between six and eight different types of bite were estab- lished for the three most frequently consumed shrub species (kermes oak, cade and whin), to take into account grazing impact and seasonal growth, but, at a given availability, an animal generally gives only three or four of them, when feeding on a shrub. Never more than three types of bites were defined for the other browse species. Due to the morphological similarity of their jaws and the selectivity of both animals, the same classes could be used for the goat and llama.

We recorded the daily grazing behavior by counting continuously the numbers and types of bites made on the different plant species, staying within 2 to 5 m of the animal and following it in a non-directive manner. On the following days, simulated-bite samples were

hand-clipped in order to estimate the weight and struc- tural composition of the different types of bites. Each class was simulated by taking 50 to 600 samples in batches of 10, 25 or 50 to assess the heterogeneity of the estimates. The more frequent the bite type, the larger the sample number.

Daily dry matter intake (DMI) was calculated as the product of the number of bites of each type by their respective weight. Intake dynamics was assessed by grouping the bite count recordings into 5-min periods (Meuret, 1989a).

Statistical analyses The effect of species (kermes oak vs. cade) on intake

rate was assessed for each animal, along periods when one of those species was consumed alone, by analysis of variance (GLM procedure: SAS, 1987). The inter- action between intake on each plant species considered as a factor and duration of intake as a covariate was tested.

3. Results and discussion

3. I. Behavior in high availability conditions

To test whether direct observation of biting can give consistent estimates of daily DMI and daily diet in this environment, we first have to compare the values obtained in high availability conditions with those found in the literature.

The goats daily DMI at pasture during daytime was 44 (d6) and 76 (d3) g DM/kg BWe.75 for periods 1 and 2, respectively, while the llamas was 42 (d3) and 53 (d3) g DM/kg BW.75 (Table 1) . DMI estimates of both animals grazing in high availability conditions (d3) are consistent with those found in the literature for intake per 24 h. The daily DMIs of South American camelids fed on Andean swards range from 35 to 65 g DM/kg BWe75 (Huisa, 1985; Reiner et al., 1987; San Martin and Bryant, 1989). Prudhon et al. ( 1993) also reviewed low levels of intake in penned or grazed lla- mas and alpacas: on similar diets, they consume 20 to 40% less feed per unit of metabolic body weight, than sheep and goats. With goats fed on pure kermes oak in digestibility cages, Nastis ( 1982) obtained 79 and 51 g DM/kg BWe75 in spring and summer, respectively. The summer intake of goats fed on Californian chap-

30 B. Dumont et al. /Small Ruminant Research 16 (1995) 27-35

Table 1

Daily DMI, grazing time and daily intake rate in the goat and llama under decreasing availability conditions in spring and summer

Goat

DMI (g)

DMI (g/kg BW.75)

GT (min)

IR (g)

IR (g/mm/kg Bw75)

Llama DMI (g)

DMI (g/kgBWa5)

GT (min)

IR (g)

IR (g/mm/kg SW)

Spring

d3

-

1445

42

575

2.50

7.310-*

d6

840

44

358

2.35

12.310-2

1

d19

850

44

586

1.45

7.610-*

895

26

523

1.70

5.010-*

Summer

d3

1460

76

456

3.20

16.710 -*

1825

53

581

3.15

9.210-*

d17 d31

785 815

41 42

352 431

2.25 1.90

11.610 -* 9.71o-2

1080 875

32 26

572 472

1.90 1.85

5.610-* 5.510w2

GT, grazing time; IR, intake rate.

arral reached 61 g DM/kg Bw. (Sidahmed et al., 198 1 ), while the winter intake of goats fed on kermes oak garrigue ranged from 60 and 84 g DMlkg BWe.75 (Cordesse et al., 1991).

Under high vegetation availability conditions, the goats diet was mainly composed of browse, whereas

Table 2 Diet ( % DMI) of the goat and the llama under decreasing availability conditions in spring and summer

Spring Summer

d3 d6 d19 d3 d17 d31

Goat QC - 40 26 31 69 49 Ro - 10 27 0 0 7 Jo - 25 5 29 5 6 Gs - 4 7 33 15 14 O.W. - 10 1 6 9 7 gr. - 11 34 1 2 17

Llama QC 11 - 20 0 11 46 Ro 0 - 6 0 0 0 Jo 27 - 6 17 32 17 Gs 4 - 5 5 0 1 O.W. 3 _ 9 0 1 2 gr. 55 - 54 78 56 34

QC, Quercus coccifera; Ro, Rosmarinus ofjicinalis; Jo, Juniperus oxycedrus; Gs, Genista scorpius; o.w., other woody species; gr., grasses.

the llamas consisted of grass. The proportion (% DM)

of browse in the goats daily diet was 89 (d6) and 99

(d3) compared to 45 (d3) and 22 (d3) in the llamas, for periods 1 and 2, respectively (Table 2). The choices made by the goat and the llama were confirmed by the evolution of the CLs of the main forage species with a

rapid decrease in kermes oak and cade availabity in the goats paddocks and of grass in the llamas (Fig. 1) . Grazing on Andean pastures, llamas generally feed on tall coarse bunchgrass communities dominated by Fes- tuca doZichophyZlu (San Martin and Bryant, 1989), but can also consume low-growing grasses or browse shrubs and trees (Fowler, 1989; Pfister et al., 1989). On the garrigue, llamas spend most of their grazing

time on grass when abundant (De Rouville et al., 1991). As for goats, they generally prefer browse to grass and forbs on various pastures. However, there is

increasing evidence that they have a flexible and oppor- tunistic grazing behavior that enables them to adapt to various range conditions (Malechek and Provenza, 1983; Lu, 1988; Narjisse, 1991; Papachristou and Nas- tis, 1993; Ramirez et al., 1993) and that clearly rules their feeding management by shepherds (Meuret, 1993). In this study, grasses seemed to be more con-

sumed during the growing season than during the sum- mer drought, as already observed by Leclerc ( 1984) or Papachristou and Nastis ( 1993).

B. Dumont et al. /Small Ruminant Research 16 (1995) 27-35

24 T

32

7s

Q Z

__--- v _______.m

----r_______--- I/ __-- _____---- __-- a-- 25 _.-- . . . . . . . . . . . . . . . . . .._.... __ . . . . . . . . . ---- 8 16 24

DV 32

Fig. 1. Evolution of the consumption level (CL) of the main forage species with time spent in the paddock.

31

3.2. Behavior under decreasing availability

conditions

The daily DMI of the two animals fell as vegetation availability decreased, but the goats intake remained 30 to 65% higher (expressed in g DM/kg Bw75). As the time spent grazing during daytime did not change, a similar fall occured in the daily intake rate (Table 1) . The goats daily intake rate ranged from 0.17 to 0.08 g DM/min/kg BW.. These values were lower than the 0.27 &-0.03 g DM/min/kg BWe.75 obtained with goats of the same breed feeding on Quercus pubescens and Q. ilex coppices (Hubert et al., 1988).

Taking into account the energy requirements of a dry goat (INRA, 1989) and the nutritive value of oak foli- age diet (Meuret, 1989a), we can estimate that a dry, non-pregnant goat of 50 kg feeding on the garrigue needs 1.4 kg DM (74 g DM/kg BW.75) per day. This suggests that the garrigue could only satisfy the requi- rements of goats when vegetation availability is high,

and that animals would need to be supplemented oth- erwise. Engelhardt and Schneider ( 1977) showed that maintenance requirements of llamas are low (61 kcal ME/kg Bw75). The llama would therefore need 1.2 kg DM (34 g DM/kg BWc.75) per day, a quantity it can obtain when the grazing impact is not too strong. However, because of the difficulties in estimating the nutritive value of garrigue diets, we consider with greatest care conclusions on the ability of goats and llamas to feed in this environment.

There were shifts in the daily diet of both animals as vegetation availability decreased (Table 2)) but the llamas diet always consisted of at least 35% DM grasses, whereas this proportion was never exceeded in the goats one. Results obtained on the two animals were confirmed by the evolution of the CLs of the main forage species in the paddocks (Fig. 1) . Kermes oak and cade were exploited by llamas to a lower extent than sward. Rosemary was only consumed by goats in spring at the end of their stay in the paddock and never

I

I i

Llama

II 0 I

1

B. Dumont et al. /Small Ruminant Research 16 (1995) 27-35

I 11 1

1 I

I Inhkeperlod

Intake period

m QC m Ro m O.W. 0 gr.

Fig. 2. Summer diet (% DM) of the llama and goat in successive 200 g DMI periods. QC, kermes oak; Ro, rosemary; o.w., other woody species; gr., grasses.

B. Dumont et al. /Small Ruminant Research 16 (1995) 27-35 33

I41 i ; L

20 40 60 80 100 120 1 Time (min)

- Cumulative DMI - - - Intake rate on cade

Fig. 3. Influence of the ingestion of cade on cumulative DMI within a meal in the goat.

accepted by llamas. Grasses were consumed by goats in spring, when the availability of most browse species had been reduced. The same behavior was observed in an Acacia karroo savanna in South Africa, in which grass was ingested in large quantities by goats when about half of the available acacia leaves had already been consumed (Teague, 1989).

3.3. Grazing dynamics

Direct observation of biting also gave informations on the sequences of choices and on intake dynamics along the grazing journey.

Proportions (% DMI) of the plant species consumed were calculated during periods in which 200 g DM were

Llama

1201P

i

_t________________/_______________________t

60 _____________ _________-____________-__________

t / -/ 1

Duration of intake (min)

ingested (Fig. 2). There were strong diurnal variations in the botanical composition of the diets. The propor- tion of browse in the llamas diet was high only in the early grazing period. When grasses and rosemary were the only species left in large quantities in the paddocks, the goat preferentially ingested them in the evening. Van Dyne and Heady ( 1965) and Obioha et al. ( 1970) reported that sheep and cattle grazed the more acces- sible forages first, to eat quickly during the morning grazing period. As browse has a greater fill effect than grasses, it is likely that the llama had the same strategy. On the other hand, under harsh pasturing conditions, the goat was first selective, and only accepted to con- sume species that still permitted a high intake rate in the evening as though it wanted to fill up its rumen before the night pause. This observation supports the suggestion of Benham ( 1984) that it is better for rumi- nants to be selective in the morning than in the evening. In the early part of the day, a selective grazing behavior prevents the rumen from being filled with low digesti-

ble material that would later limit intake, whereas unse- lective grazing in the evening tops up the rumen ready for the night when little grazing is performed.

A meal was defined as a grazing period lasting at least 20 min with no interruption longer than 15 min because the events that sometimes occur during a meal such as drinking, movements of the flock or fights are generally shorter than 15 min. It was not possible to adjust the curves of cumulative DMI within a meal vs. time to a mono-exponential model, with a continuous decrease in intake rate as in trials with penned cows

Goat

Fig. 4. Influence of the species consumed (kermes oak vs. cade) on instantaneous intake rate.

34 B. Dumont et al. /Small Ruminant Research I6 (1995) 27-35

(Suzuki et al., 1973; Faverdin, 1985), penned sheep (Forbes et al., 1972; Baumont, 1988) and caged or pasturing goats feeding on oak foliages (Meuret, 1989a). In this study, irregular curves of cumulative intake within a meal are generally the consequence of phases with an accelerated intake rate on an occasion- ally focused plant species (i.e., cade as presented in Fig. 3). Intake rate (g DM/min) was higher on cade than on kermes oak in the goat (5.09 kO.60 vs. 1.55f0.13; P

B. Dumont et al. /Small Ruminant Research 16 (1995) 27-35 35

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