There is increased global interest in the environmental impacts of farming, including the need to prevent the contamination of soil, water and air with excessive amounts of nitrogen (N) and phosphorus (P) in grazed systems. Reduction in grazing intensity has frequently been recommended to meet biodiversity and production goals in sustainable grazing systems. The objective of this experiment was to measure N and P ingestion and excretion by beef cattle grazing semi-natural pastures at two grazing intensities (Moderate or Lenient). The cattle grazing at Moderate grazing intensity had significantly more defaecations each day than those grazing at Lenient intensity (9.5 vs. 7.5) and tended to have more urinations (7.0 vs. 5.8). For the Moderate and Lenient treatments, respectively, 113 vs. 76 g N d(-1) was excreted compared with 136 vs. 94 g N d(-1) ingested; 12 vs. 8 g P d(-1) was excreted compared with 13 vs. 10 g P d(-1) ingested and urine N comprised 0.51 and 0.52 of the total N excreted each day. In improved, intensively managed grassland systems, urine N comprises a much higher proportion (approximately 0.700.85) of the daily total N excreted. The lower level found here is likely to impact on potential volatilization, denitrification and leaching losses, and these aspects should be examined further to see the extent to which semi-improved grasslands containing increased plant diversity compared with improved grasslands can deliver higher resource protection, as well as enhanced grassland faunal diversity and abundance.

Grazing semi-natural grasslands may enhance their wildlife faunal diversity and abundance by modifying the plant species composition through exploiting the dietary choices of the domestic livestock, yet diet preferences in these grasslands are often poorly understood. We therefore investigated diet selection of beef cattle in semi-natural pastures, grazed at moderate stocking (MS) or lenient stocking (LS), using the global positioning system (GPS) to track their foraging paths. This was combined with use of an automatic system to record foraging behaviour in free-ranging ruminants and measurements of vegetation structure (pasture height and plant functional groups) at a given location. The diet selected by each animal at each grazing location was then determined from a vegetation map surveyed using GPS along with a geographical information system (GIS). Patches containing clover comprised only 17.5% and 3.1% cover in the MS and LS swards, respectively. Clover was also mostly distributed in the sward as singular patches, rather than as larger aggregated clumps and it appeared that these species were not as strongly selected as has been reported for less heterogeneous pastures where they are more prevalent. This study demonstrated that GPS tracking of livestock foraging paths could be combined with vegetation mapping and automatic grazing behaviour measurements to investigate diet preference in complex, heterogeneous swards.

There is increasing global interest in the extent to which multi-species grasslands containing increased plant diversity compared with improved grasslands can also deliver higher resource protection. The objective of this experiment was to examine nutrient returns via faeces and urine by free-ranging cattle grazing semi-natural grassland which contribute to leaching losses to ground water along with volatilisation and denitrification losses to the atmosphere. Reduction of grazing intensity has frequently been recommended to meet biodiversity and production goals in sustainable grazing systems. In this experiment beef cattle were continuously stocked on semi-natural (Lolium perenne–Cynosurus cristatus) grassland at grazing intensities which were designed to either utilise herbage growth for optimum livestock production (Moderate), or to increase biodiversity by not fully utilising herbage growth (Lenient) in three replicate blocks. Observations were made in May and September of the number and timing of individual defaecation and urination events between dawn and dusk. In addition, the quantities of fresh material excreted in individual defaecation or urination events were collected and measured. For cattle grazing the Moderate and Lenient treatments, respectively, the daily number of defaecation events was 10.0 vs. 9.3 (F prob.=0.448) in May; 10.0 vs. 9.8 (F prob.=0.821) in September. The estimated daily total of fresh faeces excreted animal−1 was 10.8 vs. 9.5kg (F prob.=0.503) in May; 15.3 vs. 17.4kg (F prob.=0.480) in September. The daily number of urinations was 13.4 vs. 13.5 (F prob.=0.941) in May; 9.4 vs. 12.7 (F prob.=0.077) in September. The estimated daily total amount of urine produced animal−1 was 9.9 vs. 10.4kg (F prob.=0.808) in May; 7.2 vs. 11.9kg in September (F prob.=<0.001). Subsamples of faeces and urine were analysed for N and P concentrations. The total daily outputs of N (faeces+urine) animal−1 were 77 vs. 75gNday−1 (F prob.=0.903) in May; 96 vs. 122gNday−1 (F prob.=0.369) and urine N as a proportion of the total N excreted was 0.51 vs. 0.58 in May (F prob.=0.215); 0.53 vs. 0.59 in September (F prob.=0.464). Most of the P excreted (proportionately 0.99) was excreted in the faeces for both grazing intensities in May and September. The daily numbers of excretion events animal−1 were similar to other published values but a lower proportion of the total daily N output was excreted as urine compared with published values for cattle grazing fertilised, improved intensive swards. The potential impact of this on losses to soil water and the atmosphere should be examined.

Two diploid (Belramo and Glen), one tetraploid (Rosalin) and one tetraploid hybrid (Lolium× boucheanum Kunth) (AberExcel) intermediate-heading perennial ryegrass (Lolium perenne L.) varieties were sown in boxes (85×44×14 cm) to create micro-swards. Once established, these were defoliated at approximately 21-day intervals before being offered to individual yearling Simmental × Holstein beef heifers in short-term tests. Bite mass measured in these tests was compared with bite mass for groups of similar heifers which were rotationally stocked on the same four varieties. The boxes were weighed (± 0.1 g) before and after a period during which the heifers were allowed to take approximately 50 bites. The micro-sward methodology was developed in, 2002 and bite masses for Belramo, Glen, Rosalin and AberExcel, respectively, were 0.44, 0.46, 0.49 and 0.50 g DM bite−1 compared with 0.48, 0.49, 0.50 and 0.50 g DM bite−1 measured for rotationally stocked cattle. In 2003, the values for bite mass were 0.40, 0.41, 0.41 and 0.43 g DM bite−1 measured using sward boxes and 0.31, 0.41, 0.34 and 0.37 g DM bite−1 for rotationally stocked cattle. Whilst the rankings were similar within ploidy for the two assessment methods, there were no significant differences between the varieties. The micro-sward methodology provides a rapid, low-cost assessment method with a low seed requirement to screen for intake traits during breeding programmes and during variety evaluation. Now there is a need to develop further this methodology in order to allow small-scale simulation of other defoliation regimes, for example continuous stocking.

Electronic animal identification was used to register when sheep moved from one place to another. Non-return gates were used to control the direction of travel of the sheep past electronic identification antennas at the boundary between two areas. A personal computer program was written to control the network of identification readers and to log the ID data together with time stamps of when the IDs were captured. This allowed automatic monitoring of the periods spent by the sheep in the two areas. Forty-nine out of 50 sheep learnt to use the non-return gates when offered a concentrate feed reward during training. The method allowed error-free measurement of sheep movements between paddocks. A race could be added to the non-return gate to increase the level of work required to obtain access to another area. This would allow measurements of the motivation of sheep to obtain pasture resources and thus test the strength of diet preference at pasture.

The hypothesis that spatial memory is used less as the resource density increases was tested. On five consecutive days, individual sheep foraged for 20min in a 50m×50m bare-earth arena containing a grid of 100 bowls of which 10, 20, 30, 40 or 50 contained 25g of concentrate food. There were three replicates. Amount eaten increased linearly over days indicating that learning occurred. There was an increase in the amount eaten per full bowl visited, an increase in the cumulative number of different bowls visited by the sheep and a reduction in the path length needed to find a given number of bowls leading to improved encounter rate with full bowls. Thus, intake improved during the trial due, at least in part, to the use of spatial memory to learn full bowl locations and optimise the route taken to those locations. Amount eaten on each day was not significantly affected by resource density suggesting that sheep with less resource were able to compensate, for resource scarcity. Length of the shortest possible path required to find five full bowls and expected path length from a random walk on the grid decreased exponentially as resource density increased. Actual path length to find five full bowls also decreased exponentially as the number of full bowls increased. All treatments had shorter paths on day 5 than on day 1, but these were only significantly shorter than a random walk on the grid for 10 and 20 bowl treatments. Path length to find five full bowls on day 1 did not differ significantly from the random expectation. Actual path length to find 5 full bowls on day 5 was 0.37 of that on day 1 for the 10 bowl treatments but 0.67 for the 50 bowl treatments. Number of full bowls visited by the sheep (excluding revisits) within a day did not differ significantly between treatments. However, number of days on which any individual food bowl was visited (including 0 visit) decreased linearly as resource density increased. The proportion of full bowls visited that were revisited on the same day was significantly higher for the 10 bowl treatments. These results suggest that sheep used spatial memory to optimise their route to food bowls more effectively at lower resource density.

Four intermediate-heading perennial ryegrass (Lolium perenne L.) varieties, which in previous studies had been associated with high- or low-intake characteristics when swards containing them had been continuously stocked with sheep, were sown as monocultures. They were rotationally grazed, using 1-d paddocks, with core groups of four yearling Simmental x Holstein beef heifers in 2002 and 2003 and ingestive and ruminative behaviour, and sward factors, were measured. There were two diploid (Belramo and Glen) and one tetraploid (Rosalin) perennial ryegrass varieties and one tetraploid hybrid (Lolium x boucheanum Kunth) (AberExcel) variety. Intake rate (IR) was significantly higher in August 2003 for heifers grazing Glen than those grazing Belramo [27.5 vs. 20.6 g dry matter (DM) min(-1); P = 0.019], but there were no significant differences between varieties in two other measurement periods. This is in contrast to previous results with sheep when IR were significantly higher for Glen than Belramo and for AberExcel than Rosalin. Total jaw movement rates during grazing were significantly higher for heifers on the tetraploid swards than those on the diploid swards (87.7 vs. 83.6 jaw movements min(-1); P = 0.023) in September 2002. Ruminating time was significantly lower for heifers on the tetraploid swards than those on the diploid swards (453 vs. 519 min 24 h(-1); P = 0.012) in July 2002. Digestibility of grass snips was significantly higher on the tetraploid than the diploid swards [697 vs. 680 g digestible organic matter (DOM) kg(-1) DM; P = 0.042] in September 2003 and, within diploids, was significantly higher for Glen than Belramo (696 vs. 663 g DOM kg(-1) DM; P = 0.014). There were significant differences in sheath tube and leaf lengths and in the population density of tillers between and within ploidies, which might have been expected to have influenced intake characteristics, but this was not generally found under rotational grazing with cattle. In order to separate the effects of defoliation interval from those of grazing style of the different ruminant species, it is suggested that grass variety evaluations using continuously stocked cattle swards are required.

Fifteen intermediate-heading varieties of perennial rye grass were continuously-stocked with sheep during two years and sward surface height was maintained in the range of 4 to 5 cm. Large differences in daily dry matter intake ewe-1 were observed between the varieties suggesting that there is considerable scope for breeding improved varieties for grazing. Compared with the mean in each year, the ranges in values were proportionately 0.81 to 1.24 in 1998and 0.80 to 1.19 in 1999. Highest intakes were measured for sheep grazing 2 tetraploid hybrid varieties which also had markedly higher live weight gains ewe-1 and ha-1 compared with those grazing the 9 diploid and 4 tetraploid varieties examined. Daily intakes were not correlated with eating time but were correlated with intake rate min-1eating (r = 0.73 and 0.88 in 1998 and 1999,respectively). Animals appeared unable to compensate fully for low intake rate by increasing eating time. Intake rates were not correlated with green leaf mass, the number of grass tillers m-2 or water soluble carbohydrate concentrations in grass snips from the grazed horizon. High intake rates were achieved not only by sheep grazing highly-tillered diploid varieties but also by those grazing tetraploid hybrids with fewer tillers m-2. Other plant morphological and chemical attributes need to be explored to determine what factors might influence the intake characteristics of varieties destined for grazing so that new target traits can be identified and improved methods can be developed to screen rapidly for these traits during breeding programmes and during variety evaluation.

Fifteen intermediate-heading perennial ryegrass (Lolium perenne) varieties were grazed by sheep under continuous variable stocking management. Mean daily grass dry matter intake per ewe was positively correlated with liveweight gain per ewe (r = 0.63) and per ha (r = 0.58) over an 8-month grazing season. Daily intake was not correlated with grazing time (r = 0.12) but was positively correlated with instantaneous dry matter intake rate (r = 0.75). Breeding varieties with high intake rate characteristics should allow increases in the contribution of grazed grass to grassland-based livestock farming. There is now a need to identify morphological and chemical characteristics of varieties that are correlated with high intake rate and ha. Here we report relationships between intake and nutritional characteristics of the grass varieties, along with animal performance found in that trial.