Scottish Government

THE STATUS OF TRADITIONAL SCOTTISH ANIMAL BREEDS AND PLANT VARIETIES AND THE IMPLICATIONS FOR BIODIVERSITY

PART ONE LIVESTOCK COMPONENT

CHAPTER TWO: REVIEW OF RELEVANT RESEARCH ON THE ROLE AND PERFORMANCE OF RARE AND TRADITIONAL BREEDS

2.1 This section of the report gives an overview of the research which has been conducted on the role and performance of rare and traditional breeds. The review has been divided into four key areas.

(a) The role of the grazing process in the biodiversity of ecosystems.

(b) Research which looks specifically at rare or traditional breeds and their role in biodiversity.

(c) The performance and physical characteristics of rare and traditional breeds in relation to their modern and imported counterparts.

(d) Research into the economic and social implications of rare or traditional breeds.

A. The Role of the grazing process in the biodiversity of ecosystems

2.2 The grazing process has been the subject of research for many years and so there is a considerable body of knowledge on the dynamics of grazing. Historically, much of the research was aimed at maximizing the utilization of the grazed resource, but more recently research has been conducted on how grazing can be used to achieve environmental objectives, especially in relation to the impact on vegetation.

2.3 Much of the research has considered the effect of the intensity of grazing and the species of grazer. Compared with sheep, cattle are relatively unselective as grazers, due to their larger mouth parts (Gordon and Iason, 1989), and their lower metabolic requirements relative to their body weight means that they can survive on poorer quality forage than sheep. Thus, sheep tend to select a greater proportion of the preferred plant species and plant parts in their diet than cattle and this can affect the floristic diversity of vegetation communities.

2.4 On Nardus stricta - dominated grassland, cover of Nardus decreases with increasing grazing pressure by cattle, but with sheep there is little effect (Grant et al, 1996b). Cattle consume a greater proportion of Nardus in their diet than sheep, especially at higher grazing pressures and as a result, their diet is of lower digestibility (Armstrong et al, 1997). In some cases the cover of the broad and fine-leaved inter-tussock grass species increases (Grant et al, 1996b), but in others it does not, possibly as a consequence of site differences in nutrient availability (Common et al, 1998). Mixed grazing by cattle and sheep can bring about similar changes to that of cattle grazing alone, although the changes in the floristic composition are slower (I.A.Wright, unpublished results).

2.5 On Molinia ceruleae-dominated heath it has been shown that high levels of utilization of Molinia leaf reduces the Molinia content of the sward (Grant et al, 1996a). Floristic diversity was enhanced by grazing by cattle compared to areas that were ungrazed, where Molinia became very dominant.

2.6 On heather moorland, grazing intensity and pattern can have major impacts on floristic diversity. Grant et al (1982) demonstrated that if utilisation of the current season's shoots of Culluna vulgaris exceeded 40%, the growth of the plant was reduced. High levels of grazing of heather results in the replacement of heather by grasses, sedges and herbs. Recently, the role of the spatial distribution of grass patches within a grass/heather mosaic has been explored and it has been shown that the utilization of heather at the boundary of grass and heather is several fold higher than the average level of utilisation (Hester and Ballie, 1998). This has important implications for the dynamics of the competition between grass and heather.

2.7 On improved pasture, the level of intensity of grazing has relatively little impact on the botanical composition. Long term studies have suggested that reducing grazing pressure, and maintaining sward height of 8cm compared to 4cm has only a small effect on botanical composition (Marriott et al, 2002), although complete cessation of grazing can have a large impact on botanical composition.

2.8 Grazing intensity has a large effect on the structure of vegetation, even though the botanical composition may not be influenced greatly. Such differences in structure can lead to differences in invertebrate populations. Although understanding of these responses is not comprehensive, some studies have been conducted. Gardner et al (1996) investigated the effects of grazing on the development of heather and the effects on ground beetles. Ground beetle distribution was strongly influenced by soil organic matter content and the height of the heather. Dennis et al (1997) examined the effects of grazing regime on a Nardus- dominated sward on invertebrate populations. It was found that some of the species of ground beetle were strongly influenced by the grazing regime. It was concluded from the study that a rotation of varied management over time, including different combinations of grazing animals, would encourage a wider diversity of beetles, through the creation of a mosaic of different structures within the sward. The impact of grazing on other taxa, e.g. moorland birds and small mammals, especially in upland vegetation is not well understood, but new studies are beginning to explore these effects.

B. Research looking specifically at the role of rare or traditional breeds in the promotion or enhancement of biodiversity

2.9 There are several cases of rare or traditional breeds being used in grazing systems to promote biodiversity. The Royal Society for the Protection of Birds, for example, uses Highland cattle on some of its nature reserves. At Vane Farm reserve in Fife, a herd of Highland cattle is used to control rushes and maintain species-rich grassland. Highland cattle are also used on Rhum, where, as a result, there has been an increase in variety of plants in most plant communities. Hebridean sheep are used by Lincolnshire Wildlife Trust as part of the management of their nature reserves. However, there has been very little research done to compare the grazing behaviour, diet selection, herbage intake and impact on vegetation of rare and traditional breeds with modern or imported breeds.

2.10 One of the few studies was conducted by Newborn (2000) comparing the ability of Swaledale and Hebridean sheep to control invasive purple moor grass ( Molinia caerulea) in Yorkshire .

Table 2.1 Effects of grazing by Hebridean and Swaledale sheep on leaf density and percentage of leaves grazed in purple moor grass (Newborn, 2000)

Table 2.2 Effects of grazing by Hebridean and Swaledale sheep on cover of Calluna (%)

(Newborn, 2000)

2.11 Over a five year period (1992-1996) grazing by Hebridean sheep led to a consistently higher level of utilisation of Molinia although the overall leaf density of the purple moor grass was not significantly altered (Table 2.1). It is therefore possible that this apparent preference for purple moor grass by the Hebridean sheep could be exploited to reduce the content of purple moor grass significantly by imposing a higher stocking rate. There was a significant increase in the heather cover under grazing by Hebridean sheep (Table 2.2), although the author could not draw any conclusions about the reasons for this, except that further study is required to fully understand the mechanisms involved.

2.12 Dwyer and Lawrence (1997) observed that when Blackface and Suffolk ewes grazed in a field comprising improved pasture and semi-natural vegetation, the Suffolk ewes tended to graze the improved pasture and the Blackface ewes the semi-natural pasture. However this does not demonstrate differences in grazing behaviour, since the differences could be due to competition between the larger Suffolk sheep, and the smaller Blackface ewes for the better resource.

2.13 The difficulty with breed comparisons of grazing behaviour, is that differences between populations of animals could be learned as well as being genetic in origin. It is well recognized that animals can learn, especially from their mothers (Thorhallsdottir et al, 1990). Therefore any breed comparisons must take this into account. There is a major gap in our knowledge about the foraging behaviour of different breeds and to what extent genotype and learned behaviour influences diet selection and foraging. Research is needed in this area.

C. The performance of rare and traditional breeds in relation to their modern and imported counterparts

Cattle

2.14 The most comprehensive comparative study of traditional beef breeds with their imported counterparts was carried out by the Meat and Livestock Commission in the 1970's (Southgate et al, 1982). They looked at live-weight growth and efficiency of food utilization of steers from a range of different breeds and crosses. The trial looked at both summer and winter fattening systems. The cross-bred steers were all born to Blue-Grey or Hereford x Friesian dams. The main performance results of the trial are shown in Tables 2.3 and 2.4 for the winter and summer fattening trials respectively. It has to be borne in mind that these cattle were fed high quality fattening diets typical of intensive systems.

2.15 Although some of the larger continental breeds had higher live-weight gains, in the winter fattening system some of the traditional breeds compare very well in terms of efficiency of live-weight gain with their imported counterparts. Charolais, Limousin and Simmental crosses all performed less well than some of the traditional breeds, particularly Aberdeen Angus and Lincoln Red crosses. While purebred Luing steers were less efficient, Welsh Black steers were among the most efficient. The larger body size of the imported breeds will lead to a greater maintenance requirement. Under a summer fattening regime, the breed which displayed the greatest feed efficiency was the purebred Galloway, although the Luing was once again one of the least efficient.

Table 2.3. Daily food intake, daily live-weight gain and efficiency of live-weight gain for a range of cross-bred and pure-bred cattle on a winter fattening system (Southgate et al., 1982)

Table 2.4 Daily food intake, daily live-weight gain and efficiency of live-weight gain for a range of cross-bred and pure-bred cattle on a summer fattening system over approximately 3 months prior to slaughter (Southgate et al, 1982)

2.16 The animals from this trial were slaughtered and evaluations were made of the carcasses. The results are shown in Tables 2.5 and 2.6. In terms of total saleable meat, and the saleable meat of higher priced cuts, all the crossbreds and purebred steers performed similarly. However, the Charolais and the Limousin cross-breds had higher killing out percentages under a winter fattening regime. Under a summer fattening regime, the imported breeds again had an advantage in terms of killing out percentage. Purebred Galloways had the highest proportion of saleable meat, although all the crossbreds and purebreds were similar in terms of the proportion of meat in the higher priced cuts. Under both winter and summer fattening regimes, the imported breeds always had better conformation, although the Aberdeen Angus were only marginally lower. It should be noted that these trials were conducted indoors, with even the "summer fattened" steers being housed. Thus any potential differences between breeds in their efficiency of grazing would not have been detected.

Table 2.5 Carcass characteristics of winter fattened cattle (Southgate et al, 1982)

Table 2.6. Carcass characteristics of summer fattened cattle (Southgate et al., 1982)

2.17 Although not with Scottish breeds, a recent study by Wright et al (2000) provides one of the few examples of documented interactions between breed and grazing resource. They compared the performance of purebred Welsh Black and Charolais-cross steers when they grazed on either improved permanent pasture or on semi-natural grazings dominated by purple moor grass. It was found that there was no significant difference in live-weight gain between the breeds when grazing the improved permanent pasture. However, when grazing the semi-natural, purple moor grass swards, the live-weight gain of the Charolais-cross steers was significantly lower than that of the Welsh Black. The conclusion which was drawn was that the continental breed was less suited to grazing systems which rely on the use of semi-natural vegetation for part of the grazing season.

2.18 Apart from the data in the tables above, there has been little comparative research carried out on the characteristics of cattle breeds. In a report for MAFF, Mercer et al (1997) drew together information from a variety of sources. This information is summarised in Table. 2.7.

Table 2.7 Some physical characteristics of breeds of beef cattle ( Mercer et al, 1997)

Sheep

2.19 Comparative data for sheep breeds is even more scarce than for cattle. Mercer et al (1997) drew upon data from a variety of sources. This information is summarized in Table 2.8.

Table 2.8 Physical characteristics of a number of rare breeds of sheep (Mercer et al., 1997)

D. Research into the socio economic implications of rare and traditional breeds

2.20 There seems to have been very little work done in this area. The only published paper which was found does not deal specifically with rare or traditional breeds, but livestock in general. Waterhouse et al (1993) reviewed the development of tourist sites which attempt to interpret the work of livestock farms to visitors. They documented the numbers of these sites, showed how they have been increasing over the years, and how the number of visitors to these sites has doubled over the last 10 years. They concluded that in the correct location, and with appropriate facilities, farm based attractions have a considerable potential. Unfortunately they do not state how many of these attractions feature rare or traditional breeds as part of their marketing strategy. Research is needed into the socio-economic role of the rare and traditional breeds.