During the years 2000-2001, 7 non-lactating beef cows, 40 ewes and 40 does were managed in mixed grazing on a natural heathland vegetation plot (22 ha) with 20% improved pasture (perennial ryegrass) on a hill (1000 m a.s.l.) experimental farm located in the NW of Spain. Samples of faeces and vegetation components were collected monthly to estimate diet selection, using the alkane markers, and diet overlapping level. Animals were weighed monthly to quantify live weight changes and performance of the three livestock species during different periods (spring, summer, autumn, winter) of the grazing season.The percentage of shrubs in the diet was significantly higher in the small ruminants (ranging between 36% and 85%) than in cows (less than 25%) in any period. Gorse (Ulex gallii) and heather (Erica spp., Calluna) percentages were always significantly higher in does than in ewes, except in autumn for heather. Herbaceous component (namely grasses) was higher in cattle (75-99%) than in small ruminants (15-64%). The lowest mean dietary overlap was found between cattle and goats (50.4%), with large differences during the grazing season, ranging between 20% and 70%.The three animal species increased their live weight in the first grazing period (spring), when the mean sward height on the improved area was higher than 6.0 cm. However, when the sward height was lower than 3.5 cm (summer-winter), cows lost weight (−437 g/day) while ewes and goats were still able to increase their weight (29 and 5 g/day, respectively).Therefore, it seems that small ruminants, mainly sheep, are more suitable than cattle from the vegetation utilization and animal performance points of view, as cows were unable to maintain live weight when the preferred grass availability decreases. Goats were the species that included the highest proportion of heathland vegetation components in the diet, especially gorse, although their performance was significantly lower than in sheep. In consequence, small ruminant production systems could be more sustainable than cattle. The results indicate that mixed grazing of sheep and goats could be appropriate in these vegetation communities, allowing the development of sustainable systems, in which animal performance and the efficiency of resource use are maximized.

A mixed herd of five cows, five mares, 32 ewes and 32 goats was managed with their offspring during two consecutive years in a paddock (22.3 ha) with 76% of heathlands and 24% of improved pasture area, with the aim of studying their differences in ingestive behaviour and performance. Diet composition, dry matter intake (DMI) and digestibility (DMD) were estimated on three occasions using the alkane technique, and all animals were periodically weighed to calculate bodyweight (BW) changes per livestock unit (LU). Goats selected higher proportions of shrubs than the other herbivore species (P < 0.001). Overall, daily DMI was higher (P < 0.001) in equines (218 g/kg BW0.75) than in ruminants (174, 121 and 80 g/kg BW0.75 for cattle, goats and sheep, respectively), whereas DMD was lower (P < 0.001) in equines (569 g/kg DM) compared with ruminants (733–791 g/kg DM). During the first half of the grazing season (from late April to mid-July), dams’ BW changes per LU did not differ between species. However, during late summer–autumn lower (P < 0.001) BW losses per LU were observed in sheep and goats (–89 g/day) than in cattle (–534 g/day), being intermediate in horses (–254 g/day). For the overall grazing season, ewes and goats showed greater (P = 0.056) BW gains per LU (338 g/day) than cows and mares (178 g/day). Regarding the offspring, BW gains per LU were greater (P < 0.001) in lambs (3612 g/day) than in other species. Calves presented greater gains than kids (2647 vs 1909 g/day.LU), whereas foals showed intermediate gains (2385 g/day.LU). Therefore, under these conditions of partially improved heathlands, sheep was the most productive species. However, looking at the diet selection and digestibility, goats could complement sheep or cattle herds by achieving a more efficient utilisation of heathland vegetation, and increasing overall productivity per hectare. By contrast, horses, having high levels of grass intake, compete with cattle and sheep for pasture utilisation.

Aim: To investigate the presence of Neospora caninum in semen and blood, and the development of specific antibody and interferon-gamma (IFN-g) responses in experimentally infected bulls. Methods: Eight bulls were intravenously infected with 10 8 live N. caninum tachyzoites of NC-1 isolate. The presence of N. caninum in semen and blood was assessed using a nested-PCR procedure. PCR-positive semen samples were bioassayed using a BALB/c nu/nu mouse model. Specific anti-N. caninum antibody and IFN-g responses were also examined. In parallel, eight seronegative bulls were studied as non-infected controls. All bulls were monitored for 26 weeks. Results: All eight experimentally infected bulls showed N. caninum DNA in their semen and/or blood samples at some time during the course of the study. Parasite load in semen ranged from 0.1 to 14.5 parasites/ml (mean 6.0). N. caninum could not be detected in BALB/c nu/nu mice inoculated with PCR-positive semen samples. A significant increase in mean serum specific IgM antibody response to N. caninum was detected between 10 and 28 days post-infection (p.i.). Serum specific IgG, IgG1, and IgG2 antibody levels in experimentally infected bulls were significantly different after 21, 10, and 14 days p.i. as compared to controls, respectively. Specific anti-N. caninum IgG were detected in seminal plasma from infected bulls and values obtained were different from controls after 25 days p.i. Mean specific IFN-g responses in experimentally infected bulls were significantly higher than controls 3 days p.i. Conclusions: This is the first study to report the presence of N. caninum DNA in the semen and blood of experimentally infected bulls. Our observations indicate an intermittent presence of N. caninum in low numbers in semen and associated with chronic stage of the infection. This study is also the first to report the detection of anti-N. caninum IgG in seminal plasma of experimentally infected bulls. #

The effective degradability (ED) and the intestinal effective digestibility (IED) of dry matter (DM) and crude protein (CP) of a green Italian rye-grass (GRG) crop and its silage (ERG) were determined using in situ and particle passage techniques on three wethers, cannulated in rumen and duodenum. Two rumen incubations with duplicate bags filled with 3 g of freeze-dried samples were performed for each feed at times of 0, 2, 4, 8, 16, 24, 48 and 72 h. On each incubation, one series of bags was used to determine rumen degradation and the other was freeze-dried and pooled for each incubation time. Then two sub-samples (0.2 g) were incubated into mobile nylon bags through the entire intestine of each animal. The microbial contamination of rumen incubated residues (determined with 15 N techniques) was fitted to an exponential function. The asymptotic values (m) for DM contamination showed that silage particle reached a greater colonisation (P=0.006) but with a slower rate of microbe accumulation (P=0.03). Values of m for CP also showed that the undegradable CP fraction was mainly of microbial Abbreviations: a, soluble fraction; ADF, acid detergent fibre; ADIN, acid detergent insoluble N; b, non-soluble degradable fraction; CP, crude protein; DM, dry matter; ED, effective degradability; ED p , effective degradability calculated using k p ; ED c,p , effective degradability calculated using k c and k p ; ERG, ensiled rye-grass; GRG, green rye-grass; IED, intestinal effective digestibility; k c , rate of particle comminution; k p , outflow rate from the rumen; NDF, neutral detergent fibre; NDIN, neutral detergent insoluble N; r, undegradable fraction; SAB, solid adherent bacteria; TAA, total analysed amino acids

The foraging behaviour (grazing time and diet composition), live-weight (LW) changes and parasitic infection (faecal egg counts of gastrointestinal nematodes) of 12 beef cows, 84 ewes and 84 goats suckling their offspring, managed in mixed grazing on heathlands with 24% of improved pasture of perennial ryegrass-white clover, were studied during the years 2003 and 2006. The results showed that goats tended to graze for a longer time, and utilised significantly more heathland vegetation than cattle and sheep, including in their diet in an average of 0.39 herbaceous plants, 0.11 gorse and 0.51 heather over the grazing season, comparing with respective mean values of 0.85, 0.02 and 0.13 in cattle and sheep. Dietary overlap was higher between cattle and sheep (0.76) than between sheep and goats (0.53) or between cattle and goats (0.47). Despite the high performance of autumn-calving cows in spring, sheep had the best LW changes per livestock unit (LU) during the whole grazing season. Goats' performance per LU was lower than in sheep but higher than in spring-calving cows. Regarding offspring production, lambs had higher LW gains per LU than calves and kids. Mean nematode eggs/g fresh faeces (epg) during the grazing season were higher in goats (91 epg) compared with sheep (34 epg) and cattle (14 epg), particularly from September to December. In conclusion, sheep performed best on these heathlands with improved pasture areas if the entire grazing season was considered, despite the good level of production in spring from autumn-calving cows. The results suggested the complementary use of goats in order to increase the effective utilisation of the available vegetation, achieving production levels similar to those from spring-calving cows. Therefore, mixed flocks of sheep and goats would be the most appropriate sustainable systems from the animal production and vegetation use points of view.