Mediterranean Shrublands - DAIRY GOATS FEEDING AND NUTRITION

8 Foraging Behaviour and

Intake of Goats Browsing on

Mediterranean basin. The great climatic, edaphic and physiographical heteroge- neity of the Mediterranean areas coupled with human intervention have resulted in a large variety of plant species.

There is no commonly accepted classification of Mediterranean shrublands and each country uses its own vernacular names (Papanastasis, 2000). However, from the point of view of range management, shrublands can be subdivided into three categories: (i) maquis or matorral; (ii) garrigues (Tomaselli, 1981; Le Houérou, 1993a); and (iii) phrygana (Papanastasis, 1977).

● Maquis or matorral are xerophilous and schlerophyllous shrublands, growing on relatively deep, mainly siliceous soils (Le Houérou, 1993b;

Papanastasis, 1997, 2000). They are tall (1–3 m), dense and impenetrable plant communities dominated by a large variety of species, such asArbutus unedo L., Arbutus adrachne L., Erica arborea L., Pistacia lentiscus L., Myrtus communisL.,Quercus ilexL.,Quercus cocciferaL.,Phillyrea media L. andCistus monspeliensisL.

● Garrigues are open plant communities of relatively small (0.5–1.5-m tall) schlerophyllous shrubs growing mainly on calcareous soils (Le Houérou, 1993b; Papanastasis, 1997). They are dominated by the evergreen Q. cocciferaL. and by other evergreen or deciduous woody species, such as Carpinus orientalisMiller,Fraxinus ornusL.,Thymus capitatus(L.) Hoffsgg

& Link.,Rosmarinus officinalisL.,Erica multifloraL. andCistusspp.

● Phrygana are open communities of flammable and dwarf shrubs (shorter than 1 m) growing mainly on rocky soils (Papanastasis, 2000). These are dimorphic species, which replace their large winter leaves with smaller leaves during summer, in order to conserve water and adapt to dry conditions. The most common species areSarcopoterium spinosum(L.) Spach., Phlomis fruticosaL.,Cistusspp.,Coridothymus capitatus(L.) Reichenb. Fil.

andSalvia officinalisL.. Phrygana are mainly distributed in the eastern part of the Mediterranean area, including Greece.

Garrigue open shrublands are more available to livestock and thus more produc- tive than maquis. Phrygana plant species are not palatable for livestock, being eaten only in extreme situations. Nevertheless, they are important for the richness of herbaceous species (Papanastasis, 1997).

In the past, since goats were blamed for deforestation and deterioration of rangelands, legislation to limit goat rearing was introduced. Therefore, instead of excluding goats from forests, Papanastasis (1997) suggested an integration policy in which livestock grazing integrates with forestry and other land uses. Nowadays, rearing grazing goats is often considered as an alternative activity which can pro- tect forests and shrublands from wildfires (Yiakoulakiet al., 1999), reduce the cost of animal production and revitalize abandoned rural areas.

Foraging Behaviour of Grazing Goats

Goats are able to thrive on marginal areas, using low-quality natural resources which cannot be efficiently used by other domestic ungulates. Due to their

anatomic and physiological characteristics, goats exhibit a very flexible foraging behaviour. Actually, these animals are not considered as exclusive browsers but mainly as ‘opportunistic feeders’ that have a selective foraging behaviour affected by the interactions among animal, environmental and plant characteristics.

Animal characteristics

Goats are well known for utilizing a wide array of vegetation types, including shrubs, trees and herbaceous species. They are also able to: (i) graze very short herbage, as sheep do (Narjisse, 1991); (ii) feed on plant species with thorns and spines; and (iii) stretch upwards on their hind legs (bipedal stance), selecting foliage from the upper vegetation layer (Fig. 8.1).

This unique foraging behaviour is mainly due to their physical body structure (low body mass, small and sharp-shaped mouth, mobile upper lip and prehensile tongue), high digestive capacity (Hadjipanayiotou and Antoniou 1983; Howe and Barry, 1988) and rumen microflora (Molina Alcaideet al., 1997). Further- more, goats are able to consume much more tannin-rich browse resources and

Fig. 8.1. Goat (local breed) in bipedal stance selecting foliage of kermes oak (Quercus coccifera L.) in a Mediterranean shrubland in northern Greece.

(Photograph courtesy of M.D. Yiakoulaki.)

to digest them more efficiently than other domestic animals (Dominiqueet al., 1991; Narjisse, 1991; Silanikove, 2000). This is related to their higher ability to neutralize the negative effects of tannins on palatability and digestibility (Silanikove et al., 1996a). It seems that both salivary (i.e. high secretion of proline-rich proteins) and, above all, ruminal mechanisms are involved in the neutralization of the anti-nutritional effects of tannins in goats. Likewise, ruminal fermentation and adaptation of rumen microbes to terpenes may also enable goats to more efficiently use terpene-rich foods (Landauet al., 2000).

Breed and physiological stage of goats also influence their foraging behaviour. For example, ‘rustic’ breeds (wild goats, desert Bedouin goats) utilize harsh pastures better than do Swiss Saanen goats (Silanikoveet al., 1993). Furthermore, lactating Sarda goats spend more time grazing compared with dry or pregnant ones (Fig. 8.2), due to their higher requirements (Decandiaet al., 1997a). By selecting pasture plants or plant parts higher in nutritive value than the average and avoid- ing consumption of the harmful, goats express a degree of nutritional wisdom (Provenza and Balph, 1990; Provenza, 1995). Forage selection is believed to be genetically transmitted (Cooperet al., 1988) and most information is transferred to the offspring during the weaning period (Thorhallsdottiret al., 1987). An inter- esting ‘maternal effect’ on foraging behaviour has been found in kids, since the group reared by ewes on pasture had a higher preference for white clover (Trifolium repensL.) than that reared by goats (Orret al., 1995). However, it seems that preference for a specific feed is not permanent. Food preference is adjusted as sampling continues, depending on the ‘internal nutritional value’ of different species, such as post-ingestive effects. Animals raised in different environments express different dietary preferences. In fact, Rosenberger and Meuret (1985) found that goats previously adapted to browse oaks had a different dietary selection from those that had never utilized that species before. This indi- cates that dietary selection is influenced not only by genetics but also by the pro- cess of learning (trial and error) and experience. Additionally, animals exhibit different preferences if exposed to forage rich in aromatic compounds, such as phenols and terpenes. Goats discriminate between plants with different levels of monoterpenoids less than sheep (Narjisse, 1991).

0 10 20 30 40 50 60 70

% of total observation time

Grazing Resting Searching Moving

Lactation Dry Pregnant

Fig. 8.2. Feeding activities of Sarda goats, expressed as percentage of the total observation time, grazing on Mediterranean shrublands. (Adapted from Decandia et al., 1997a.)

In general, food selection is affected by the interactions between the senses of taste and smell and mechanisms sensing the consequences of food ingestion.

Experienced sensations may be, for example, satiety (when animals ingest ade- quate kinds and amounts of nutritious foods) or malaise (when animals ingest excess of nutrients or toxins or low-nutrient feeds) (Provenza, 1995).

Environmental characteristics

Environmental factors highly affect the foraging behaviour of goats. Although goats adapt to harsh and arid environments better than other ruminants (Shkolniket al., 1987; Silanikove, 2000), they are sensitive to low temperatures (Narjisse, 1991), high rainfall (Decandia et al., 1997b) and high wind, which reduce their grazing activities. In fact, climatic conditions within each season affect their dietary selection. For example, goats consume more herbaceous species on cold days, whereas they browse more on hot or rainy days, possibly using the woody overstorey as shelter (Landauet al., 2000).

Pasture characteristics

Changes in forage availability throughout the year influence diet selection of grazing goats (Provenza and Malechek, 1983; Rubinoet al., 1988; Fedeleet al., 1993; Kababyaet al., 1998), since they adapt their choice according to what is available in the pasture. When forage availability decreases dramatically (Yiakoulakiet al., 1999), goats shift their diet and may even consume the bark of pine trees (Pinus brutiaTen.), which has a very low nutritive value (crude protein (CP) content of 33 g per kilogram of dry matter (DM)). By contrast, high biologi- cal diversity within the Mediterranean maquis vegetation increases shrub intake by goats (Rogosicet al., 2006a).

For a long time, goats were considered as obligatory browsers. However, sev- eral experimental results in Mediterranean areas have shown that, during the green season, goats tend to select forage resources with higher nutritive value than those selected by obligatory browsers, such as herbaceous species (Narjisse, 1991;

Papachristou and Nastis, 1993; Yiakoulaki and Nastis, 1995; Kababya et al., 1998). For example, in Corsica, woody species constituted 75% of goats’ diet during winter, but only 15% in spring, during grass regrowth (Leclerc, 1984). In Israel, Mamber goats with a low supplementation level spent 60% of the average eating time browsing the maquis vegetation and 40% grazing grasses in winter, whereas they grazed grasses for 60% of the eating time in spring (Fig. 8.3).

Goats are able to ingest diets with higher nutritive value than what is pre- dicted on the basis of botanical and chemical composition of the pasture. For example, the diet selected by lactating Sarda goats grazing on lentisk-based shrubland (P. lentiscusL.) was different from the botanical composition of the pasture (Fig. 8.4) (Decandia et al., 2000a,b). In particular, goats consumed more grasses than other plants during spring, although lentisk was the main component of the pasture. In fact, even if lentisk was the most widespread species in the pasture (60% in summer), it constituted less than 20% of goats’ diet,

due to its very high tannin level (20%, DM basis). However, during summer goats shifted their diet and ingested fewer grasses, as a result of their lower nutritive value, and more shrubs such asRhamnus alaternusL. (included in the category of other shrubs; Fig. 8.4), which has a relatively high CP content and a low tannin level.

0 20 40 60 80 100

% of total grazing time

Autumn Winter Spring Summer

Grasses Shrubs Trees

Fig. 8.3. Grazing time of Mamber goats on grasses, shrubs and trees throughout the year. (Adapted from Kababya, 1994.)

Spring

0 10 20 30 40 50 60

Pistacia lentiscus

Myrtus communis

Rubus ulmifolius

Other shrubs

Lonicera implexa

Rubia peregrina

Smilax aspera

Quercus spp.

Pasture Diet

Grass

Summer