Livestock grazing intensity affects abundance of Common shrews (Sorex araneus) in two meadows in Denmark

Background  

Current nature conservation in semi-natural grasslands often includes grazing and hay cutting, as well as the abandonment of draining. Semi-natural grassland and in particular meadows constitute important habitat type for a large number of animal species in today's fragmented and intensively cultivated landscape of Europe. Here we focus on the population characteristics of Common shrews Sorex araneus in relation to livestock grazing intensity in two wet meadows in western Denmark.     

COMPARATIVE STUDIES OF PERENNIAL RYEGRASS. TIMOTHY AND MEADOW FESCUE.

Hays made, mainly in May, from pure swards of perennial ryegrass, timothy and meadow fescue were fed to 8-month old steers in 1963 and to yearling steers in 1964. High-quality hay was obtained, but no significant differences in growth rate were observed between calves fed on hays from the 3 species. In 1963, barley (1.5 kg DM/ head per day) was fed, in addition to the hays, to half the animals and resulted in a significant increase in live weight gain. The productivity, in terms of liveweight gain/ unit area, of each species when managed for hay and‘zero grazing', or hay and grazing, was calculated. On this calculation perennial ryegrass was the most productive species.     

An evaluation of the hygienic quality in single‐species hays and commercial forages used in equine nutrition

Pulmonary diseases such as recurrent airway obstruction have become a major concern in the horse industry. Airborne dust, including aeroallergens from forages, is suspected to be the main factor in its aetiology. Hypothesizing that grassland flora could affect hay hygienic quality, and therefore have implications for the respiratory health of horses, we compared five single‐species hays (Trifolium repens, Lolium perenne, Alopecurus geniculatus, Poa trivialis and Holcus lanatus). Multi‐species hay from Normandy, and different commercial forages (single‐species haylage, multi‐species haylage, Crau hay and hay from Swiss mixing), chosen to represent current horse forages, were also investigated. Dust, moulds, pollens and endotoxins were different among forage types, while mycotoxins were not detected in any of the forage types. Holcus lanatus hay was the dustiest among the single‐species hays but also the least contaminated by moulds. A particular mould profile was associated with each plant species. The four commercial forages appeared to have a better hygienic quality than the multi‐species hay. Among commercial forages, the single‐species haylage was the least dusty but also the most contaminated by moulds. Overall the results suggest that the hygienic quality of equine forages could be improved by an appropriate choice of grassland species.     

A COMPARISON OF NUTRIENT LOSSES IN BALED HAY MADE FROM FORAGE-HARVESTED, CRIMPED OR TEDDED SWARDS WITH THOSE IN BARN-DRYING

Two experiments were conducted to study the effect on nutrient loss and feeding value of making hay by different means, using a barn-drier, a forage-harvester, a crimper and conventional tedding. Both forage-harvesting and crimping of the herbage significantly increased the rate of drying, compared with tedding alone. In Exp. 2 this effect enabled the crimped and forage-harvested hays to be baled for storage 3 days earlier than the tedded hay. The use of the forage-harvester significantly reduced the yield of herbage compared with conventional mowing. Nutrient losses from cutting until storage were highest for the forage-harvested hays, the loss of dry matter between cutting and storage in the forage-harvested hays being 39·9 and 19·3%, respectively, in Expt 1 and 2 with corresponding losses in the conventionally made hays of 7·1% and 9·3%. Crimping the hay resulted in higher nutrient losses than tedding. In Expt 2 there was a loss of dry matter of 17·5% in the conventionally made hay during an 18-week storage period, compared with 3·6% in barn-dried hay, 10·8% in forage-harvested hay and 8·8% in crimped hay.
In Expt 2, in which digestibility determinations were made, conservation decreased the total digestible nutrients and starch equivalent in all treatments. The use of the barn-drier gave the most efficient conservation of total digestible nutrients, followed by the crimped, forage-harvested and conventional treatments in that order. The starch equivalent values of hays made from the same sward were 43·0 when barn-dried, 39·8 when crimped, 38·6 after forage-harvesting and 31·6 after tedding.     

Factors affecting digestibility of temperate forages from seminatural grasslands: a review

Abstract To indicate possibilities for the use of forages from seminatural grasslands in ruminant production systems, a literature study to describe the nutritive value of those forages was carried out. In species‐rich grasslands, the digestibility of forages is usually lower than the digestibility of forages produced by grasslands used for intensive production. There is also more variation within a species‐rich sward, because of different stages of maturity of the individual species and because of likely variations in digestibility among forage species independent of stage of maturity. Moreover, the presence of dicotyledonous species may have a positive or negative effect on digestibility. In forages from seminatural grasslands, the relationship between chemical composition and digestibility differs from that of Lolium perenne, which is often used as a research standard. Therefore, predictions of the digestibility of species‐rich forage can be inaccurate. The relationship between in vivo and in vitro digestibility may also be different from the relationship that is common for L. perenne. In some cases, the in vivo digestibility is higher than the in vitro value, as calibrations are based on L. perenne. Therefore, the quality of forages from seminatural grasslands might be higher than predicted, and this may increase the scope for practical use of this kind of forage in ruminant nutrition systems.     

The effect of herbage surface water and the provision of supplementary forage on the intake and feeding behaviour of cattle

High rainfall and the corresponding low herbage DM content has been shown to adversely affect cattle intakes and production. This could arise from physical restrictions on intake or digestion rate, or other behavioural limitations such as reduced palatability. A knowledge of the reason for the intake reduction would assist in determining the optimum supplement to feed. Eight steers were offered four diets in a changeover design. The diets were: A, cut herbage; B, cut herbage with added surface water; C, as B but with a low dry matter (DM) forage supplement (silage); and D, as B but with a high DM forage supplement (hay). The addition of surface water to herbage reduced DM intake and feeding time but had no effect on biting rate or rate of intake. Neither hay nor silage was eaten in sufficient quantities to restore DM intake, even though the silage was of similar nutrient composition to the herbage.     

In vitro fermentation patterns and methane production of sainfoin (Onobrychis viciifolia Scop.) hay with different condensed tannin contents

Sainfoin (Onobrychis viciifolia Scop.) is a perennial legume recently reappraised for some positive characteristics leading to highly satisfactory animal performance. Sainfoin’s characteristics may be partly explained by the presence of moderate levels of condensed tannins (CTs) able to protect dietary protein from microbial degradation in the rumen. Decreased CH₄ emissions have been reported for ruminants consuming CT‐containing forage. The aim of this study was to evaluate the effects of CT content on the in vitro fermentation characteristics and kinetics and methane production of four samples of O. viciifolia cut at different phenological stages. Sainfoin hays and one sample of alfalfa hay were incubated at 39°C in anaerobiosis using the in vitro gas production technique. The chemical composition, tannin content and fermentation characteristics and kinetics of sainfoin samples were significantly affected by phenological stage. After 48 h, the CH₄ production in sainfoin hays showed a tendency to increase with the advancement of phenological stage [from 38·6 to 49·8 mL g⁻¹ of degraded organic matter (OM)]. The best period to cut sainfoin for hay making is between early and late flowering, when the forage combines high OM digestibility, low CH₄ production and more efficient microbial fermentation.     

Effects of cutting or grazing grass swards on herbage yield, nitrogen uptake and residual soil nitrate at different levels of N fertilization

On a Flemish sandy loam soil, cut and grazed swards were compared at different levels of mineral nitrogen (N) fertilization. Economically optimal N fertilization rates were 400 (or more) and 200 kg N ha^?1 yr^?1 on cut and grazed swards respectively. Considering the amounts of residual soil nitrate‐N in autumn, these N rates also met the current Flemish legal provisions, i.e. no more than 90 kg ha^?1 nitrate‐N present in the 0–90 cm soil layer, measured between 1 October and 15 November. The N use efficiency was considerably higher in cut grassland systems than in grazed systems, even when the animal component of a cut and conservation system was included. The results indicate that, for cut grasslands, two N application rates should be considered: intensively managed grasslands with high amounts of N (400 kg ha^?1 yr^?1 or more) or extensively managed grasslands with white clover and no more than 100 kg N ha^?1 yr^?1.     

Interactions between leaf lifespan and defoliation frequency in temperate and tropical pastures: a review

In continuously stocked swards or pastures the frequency at which individual tillers and individual leaves are defoliated by ruminant livestock, relative to leaf lifespan of the grass species within the sward, determines the proportion of each leaf defoliated before senescence, and hence the efficiency of harvesting of herbage. In this paper, sets of data obtained in a range of climatic conditions and with a range of grass species are used in order to document this relationship. It is shown that the frequency of defoliation of individual tillers or individual leaves is closely linked to the average stocking density used within a period of time for maintaining a steady state sward or pasture height, herbage mass or leaf area index. Consequently, any decrease in herbage growth rate should lead to a decrease in the efficiency of harvesting of herbage and then to a more than proportional decrease in total herbage consumption by ruminant livestock. These effects will be more important for grass species having short leaf lifespan than for species with long lifespan. In rotational stocking, the link between herbage growth rate and frequency of defoliation of leaves can be broken by controlling the grazing interval, so any decrease in herbage growth would not be systematically associated with a decrease in efficiency of harvesting of herbage. Rotational stocking should be more efficient than continuous stocking in low herbage production conditions, while in high herbage production systems rotational and continuous stocking would have similar efficiency. The implications of these conclusions for the management of swards and pastures to meet different objectives are discussed briefly.     

Degradation of nitrogenous compounds in conserved forages in the rumen of dairy cows

Degradation in the rumen of dairy cows of nitrogenous compounds in 35 grass silages and 12 grass hays was studied by means of the nylon bag incubation technique. Silages varied in dry matter content, crude protein content and date of harvesting; hays varied mainly in crude protein content. Measurements in both forages were washable (W), degradable (D) and undegradable fraction (U) and rate of degradation (ks) of D. W and U were measured as the residue after washing without incubating (W) or after 336 h in the rumen (U). N escape (E) was calculated from these data, assuming a ruminal passage rate of 4·5% per hour.
E (N escape from the rumen) in hays was substantially higher than in silages, mainly because a large proportion of N compounds in silage became soluble during the ensiling process. Of the total variation in E, around 80% could be explained in both forages. In silage, E was positively influenced by dry matter content, negatively by crude protein content and positively by the number of days elapsed since 1 April. This effect of day of harvesting was mainly through an increase of U and may not be beneficial to the animal. In hays crude protein content was the major factor explaining variation in E.     

Impact of cutting frequency on the vigour of Rumex obtusifolius

The control of Rumex obtusifolius, even with the use of herbicides, is difficult in permanent grasslands where R. obtusifolius reduces both productivity and nutritive value of herbage. It is important to find alternative approaches to managing R. obtusifolius. Two greenhouse experiments were conducted to compare the impact of different cutting frequencies, which simulated grazing (three cuts), silage making (two cuts) and hay making (one cut) on shoot and root measurements of the vigour of R. obtusifolius. In both experiments the same cutting frequencies were imposed but in Experiment 1 the treatments were imposed for 2 years and in Experiment 2 for 1 year. Compared to the silage‐making and hay‐making treatments, there was a reduction in the vigour of the aerial parts of R. obtusifolius on the grazing treatment, associated with a reduction in the number of leaves (Experiment 1), in the size of the largest leaf (Experiment 1) and in the herbage mass of dry matter (Experiments 1 and 2). Roots had higher concentrations of total soluble sugar and lower concentrations of starch in the grazing treatment than in the other treatments. These results showed that a reduction in the vigour of R. obtusifolius in permanent grasslands is possible only if the plants are submitted to a high frequency of defoliation under cutting or grazing.     

Effects of the field drying of herbage on sward regrowth

Grass which had grown without interruption from late April was cut as for hay in early July in each of 2 years. Fifteen dates of removal of the cut herbage were compared ranging, at 1-d intervals, from the day of cutting to 14 d after cutting. Sward regrowth was studied.
A delay of 5 d in removing cut herbage reduced herbage dry matter harvested during the remainder of the growing season by 9% and a delay of 10 d reduced yield by 16%. Delaying the removal of cut herbage reduced the density of grass tillers considerably in the short term, but the effect had worn off in 8 to 12 weeks. The presence of cut herbage reduced the rate of extension of leaf blades considerably. Delaying the removal of cut herbage reduced the area per leaf blade and the weight per unit area and these effects persisted for several weeks. Grass growing under cut herbage had a less negative leaf water potential and a rather cooler but much darker environment in which to grow than uncovered grass.     

Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 2. Diet selection

Reduction in grazing intensity and the use of traditional instead of commercial breeds have frequently been recommended to meet biodiversity and production goals in sustainable grazing systems. The impact of such practices within a range of contrasting grassland vegetation types was studied. This paper describes the effects on foraging behaviour in a study conducted over three years on mesotrophic or semi-natural grasslands in UK (steers), Germany (steers), France (heifers) and Italy (sheep). Three treatments were performed: (i) a moderate grazing intensity using a commercial breed, (ii) a more lenient grazing intensity with a commercial breed and (iii) a more lenient intensity with a traditional breed. Livestock at all sites preferentially selected bites containing legumes and forbs, and also short rather than tall vegetative patches. Grazing intensity affected not only diet consumed, largely reflecting the different availabilities of dietary components, but also some differences in diet selection. Livestock grazing the more productive mesotrophic grasslands more frequently exploited short patches of higher nutritive value, which is expected to reinforce the spatial heterogeneity of the pastures. Studies in the UK and Germany also revealed that steers showed a more pronounced selection for short patches at the lenient grazing intensity. More homogeneous grazing by livestock on the semi-natural grasslands with fine-scale heterogeneity is likely to decrease their spatial heterogeneity. There were few differences in the choices made by commercial and traditional breed livestock. North Devon steers in the UK expressed a greater selection for tall grass-forb bites than Charolais × Holstein crossbreds, whereas traditional breeds appeared slightly less selective than commercial breeds at the other three sites.     

Evaluation of propionic acid-treated hay as a feed for growing sheep

Two experiments were carried out to evaluate propionic acid-treated hay as a feed for sheep in which eighteen ewes (experiment 1) and eighteen ewe lambs (experiment 2) were fed ad libitum on hay only. At feeding, the propionic acid-treated hays had higher D-values and water-soluble carbohydrate concentrations, but a lower dry matter concentration, than the untreated hays. The voluntary feed intake and liveweight gain of the sheep fed on two acid-treated hays and on an untreated hay in experiment 1 were similar. In the second experiment an acid-treated moist hay was eaten in greater amounts by the sheep and liveweight gains were greater than on the corresponding untreated hay, but were not significantly different from those of sheep fed on field-cured hay.     

SOME FACTORS AFFECTING THE INTAKE OF ROUGHAGE BY SHEEP

The dry-matter intake of silage was increased when the silage had a higher dry-matter content and when the time of access to the silage was increased from 3 to 24 h. Concentrate supplementation had a greater influence in depressing the intake of hay than that of silage. Only a small difference was observed in the replacement of hay by concentrates when the concentrates were given with two hays of different dry-matter digestibility. Concentrates with a relatively high protein content depressed roughage intake to a lesser extent than concentrates with a low protein content.     

Seasonal dynamics of biomass production and herbage quality of three grasslands with contrasting functional compositions

Classifying grasses into plant functional types (PFT) according to their strategy of nutrient capture (PFT A, B and b) or nutrient conservation (PFT C) is claimed to predict variability in biomass production and herbage quality in grasslands. PFT A, B and b are characterized by higher production than PFT C, with higher nutritive value, which decreases rapidly. PFT C is characterized by lower nutritive value, which remains more stable in time. The aim of this study was to quantify the consequences of PFT composition at the community level on the seasonal dynamics of biomass and herbage quality for livestock feed. We studied three grasslands located in the same area with contrasting PFT composition and classified PFT A, PFT Bb and PFT C. The dynamics of vegetation stages, dry‐matter yield and nutritive value were followed over three vegetation cycles in 2007–2008. In the first cycle, biomass accumulation was high for the PFT A and PFT Bb grasslands and the high quality of herbage declined rapidly with the reproductive development. By contrast, biomass accumulation was slow in the PFT C grassland, with a lower quality that declined slowly, consistent with the later reproductive development. For regrowth cycles, the same ranking of grasslands was observed for biomass accumulation, and differences in digestibility were similar to those observed at the beginning of the first vegetation cycle. Combining type of grassland with sum of temperature for the first cycle and regrowth days for the second and third vegetation cycles provided quantitative models of herbage biomass and quality.     

Effects of residual dry matter on net primary production and plant functional groups in Californian annual grasslands

A five‐year experiment tested the response of above‐ground net primary production (ANPP) and plant functional groups to manipulations in residual dry matter (RDM), reflecting typical grazing practices in Californian annual grasslands. The RDM treatments were 225, 560, 900 and 5000 kg ha^?1 with the latter treatment representing no grazing by livestock. ANPP in autumn, winter and spring showed a strong year × RDM interaction indicating that, in periods with higher herbage mass, the highest RDM treatment, representative of no grazing, was usually more productive. However, the opposite pattern was observed for the autumn period when ANPP was lowest. Random effects models indicated that at most 0·20 of the variation in ANPP for any of the three seasons stemmed from RDM treatments, with the remaining variation partitioned among temporal and spatial dimensions or not explained. Cover of grass species was highest under the highest RDM treatment in four of the five years, and lowest for the lowest RDM treatment compared with the two intermediate RDM treatments in the two years with the highest herbage masses. Cover of forbs and clover was higher on the lowest RDM treatment and lower on the highest RDM treatment than on the intermediate treatments. The results suggest that residual RDM values above 550 kg RDM ha^?1 are appropriate for annual grasslands with a mean annual precipitation of more than 400 mm and offer a compromise between herbage use and promotion of future productivity and diversity, but direct control of ANPP and composition via management is not attainable because the environmental factors are predominant.     

Herbage mass and nutritive value of herbage of extensively managed temperate grasslands along a gradient of shrub encroachment

Semi-natural grasslands often serve as important reserves of biodiversity. In Europe extensive grazing by livestock is considered an appropriate management to conserve biodiversity value and to limit shrub encroachment. However, little is known about the influence of shrubs on agronomic values. A gradient analysis of shrub-invaded temperate grasslands (from shrub-free to pioneer forest) in Germany was carried out to test the hypothesis that herbage mass and variables describing nutritive value of herbage decrease with increasing shrub encroachment. The herbage mass of dry matter (DM), variables describing the nutritive value of herbage, composition of the vegetation and mean of Ellenberg's indicator values were analysed with respect to the extent of shrubs. There was a reduction of herbage mass of DM from 3570 to 210 kg ha⁻¹ with increasing shrub encroachment. Metabolizable energy concentration of herbage ranged from 8·9 to 10·2 MJ kg⁻¹ DM and crude protein concentration from 72 to 171 g kg⁻¹ DM, both measures being positively correlated with shrub occurrence. Increasing shrub occurrence was associated with a decrease in water-soluble carbohydrates concentration (from 151 to 31 g kg⁻¹) and a reduction in the indicator 'forage value'. The results indicate a potentially large agronomic value for shrub-encroached temperate grasslands.     

The effect of propionic acid on the storage losses of hay

Storage losses in moist hay treated with propionic acid were compared with those occurring in untreated moist hay in two experiments and with field-cured hay in three experiments. Dry matter losses in treated hays ranged from 41 to 8.6% and from 1.7 to 12.6% in untreated hays. Digestible organic matter losses in both treated and untreated hays were generally greater than dry matter losses. Only in one experiment did propionic acid application significantly reduce nutrient losses in moist hays. Nutrient losses, and water-soluble carbohydrate losses in particular, were shown to be correlated with maximum and cumulative bale temperatures during storage in two of the experiments. The rise in hale temperatures during storage was reduced in all three experiments, to a greater or lesser extent, by application of the additive. Loss of propionic acid from the hay during and after application was very large. In the three experiments 86.2, 85.3 and 85.6% of the acid applied was lost by the end of the storage period. Acid distribution studies indicated that variation in acid concentration within bales was as great as between bales. It was concluded that more research is needed into applicator design and position on the baler and into alternative application methods if the benefits of propionic acid as a moist hay preservative are to be fully exploited.     

Effects of livestock breed and grazing intensity on grazing systems: 3. Effects on diversity of vegetation

Finding an optimal balance between livestock production and grazing impact on plant biodiversity is an important issue in the design of grazing systems. This paper describes a study of the effect of two levels of grazing intensity combined with different animal breeds on plant biodiversity and sward structural diversity of semi-natural grasslands conducted over 3 years in the United Kingdom (UK), France (F), Germany (D) and Italy (I). There were three treatments at each site: moderate grazing intensity with a commercial breed (MC), lenient grazing intensity with a commercial breed (LC) and lenient grazing intensity with a traditional breed (LT). Grazing livestock were cattle in the UK, F and D, and sheep in I. Only grazing intensity had clear effects on vegetation diversity, the effects depending on site-specific vegetation characteristics. In more diverse pastures with finer scale heterogeneity in F and I, there was little effect of the treatments. In less diverse swards with higher grass dominance and coarse-scale heterogeneity, the number of species decreased from initial levels on the lenient grazing intensity treatments (treatments LC and LT), because of increased dominance of grasses reducing the cover of other species, particularly legumes. The structural diversity of the pastures was more affected by level of grazing intensity than botanical diversity. In more diverse, semi-natural grasslands, structural heterogeneity was not affected by the treatments. In less diverse, more productive swards, structural heterogeneity decreased where large patches were initially found on the UK site, and increased where smaller patches were initially found on the D site. It is concluded that management systems to conserve diversity need to consider carefully the background environment, and that more knowledge of the mechanisms involved is needed at farm and landscape scales.