Diet selection and performance of horses grazing on different heathland types.

The number of horses in northern Spanish mountains has increased in recent decades, but little is known about their grazing behaviour, performance and potential for foal meat production. This research aimed to study the diet selection, liveweight (LW) changes and parasitic status of dry and lactating mares, and foals' LW gains, grazing on heathlands with different botanical composition. The experimental design consisted of three vegetation types: dominated by heather (Ericaceae) species (H), dominated by gorse (Ulex gallii; G) and co-dominated by gorse and heath-grasses (G-G), with four replicates per treatment (12 paddocks of 1.2 ha). The study lasted three grazing seasons (2010-12). Each year, 24 crossbred mature mares (310±52 kg LW) were used, managing one lactating mare with her foal plus one non-lactating mare per paddock from May to late summer or early autumn. In the case of H paddocks, animals had to be removed before (late August to early September) because of apparent loss of body condition. Animals were periodically weighed. Mares' diet composition was estimated using alkane markers, analysing the discrepancies in alkane concentrations between dietary plant components and faeces. Faecal samples were also analysed for gastrointestinal nematodes ova. Chemical composition of the main plant components (i.e. heather, gorse and grasses) revealed a low nutritive value, averaging 79, 115 and 113 g CP/kg dry matter (DM), respectively, that could restrict livestock performance. Mares initially selected gorse and grasses (0.47 and 0.40, respectively, in 2010), increasing heather consumption over time (from 0.13 in 2010 to 0.29 in 2012) as gorse availability decreased. The performance of both mares and foals was lower in H compared with G and G-G paddocks (-216 v. 347 g/day for mares, P<0.01; 278 v. 576 g/day for foals, P<0.05), whereas LW changes were more favourable in dry mares than in lactating ones (241 v. 78 g/day; P<0.05). Small strongyle (Cyathostominae) egg counts in mares' faeces increased across the grazing season with no differences between treatments. These results indicate that grazing by horses on gorse- and grass-gorse-dominated shrublands could be sustainable at least during part of the year (4 to 6 months). However, heather-dominated heathlands are not able to meet the nutritional needs of horses even for a short time (2 to 4 months). Nevertheless, the low nutritive quality of these vegetation communities, especially in autumn, requires animal access to other pastures with a higher nutritive value, or supplementary feeding, to enhance foals' growth and maintain sustainable grazing systems with productive herds.

Comparison of feed intake, digestion and rumen function among domestic ruminant species grazing in upland vegetation communities.

This study aimed to compare feed intake, digestion, rumen fermentation parameters and bacterial community of 5 beef cows, 12 crossed ewes and 12 goats grazing together in spring-early summer on heather-gorse vegetation communities with an adjacent area of improved pasture. Organic matter intake (OMI) and digestibility (OMD) were estimated using alkane markers. Ruminal fluid samples were collected for measuring fermentation parameters, and studying the bacterial community using terminal restriction fragment length polymorphism (T-RFLP). Spot samples of urine were taken to determine purine derivative (PD) and creatinine concentrations to estimate microbial protein synthesis in the rumen. Herbaceous species were the main dietary component in all animal species. Cattle had higher (p < 0.05) daily OMI (g/kg LW0.75 ) and OMD, whereas sheep and goats showed similar values. The highest ammonia concentration was observed in sheep. Total VFA, acetate and butyrate concentrations were not influenced by animal species, while propionate concentrations in goats were 1.8 times lower (p < 0.05) than in sheep. Acetate:propionate ratio was greater (p < 0.05) in goats, whereas cattle excreted more allantoin (p < 0.05). Estimated supply of microbial N was higher in cows (p < 0.01), whereas the efficiency of microbial protein synthesis was lower (p < 0.01) in this animal species. Hierarchical clustering analysis indicated a clear effect of animal species on rumen bacterial structure. Differences among animal species were also observed in the relative frequency of several T-RFs. Certain T-RFs compatible with Lachnospiraceae, Proteobacteria and Clostridiales species were not found in goats, while these animals showed high relative frequencies of some fragments compatible with the Ruminococcaceae family that were not detected in sheep and cattle. Results suggest a close relationship between animals' grazing behaviour and rumen bacterial structure and its function. Goats seem to show a greater specialization of their microbial populations to deal with the greater fibrous and tannin content of their diet.

Productive responses of breeding Cashmere goats and their kids to different stocking rates on improved upland pastures.

Although goat meat production could be an option for diversification in improved upland pastures in northern Spain, precise information on the optimal grazing management to enhance goat performance and maximize production per unit land area is lacking. The objective of this study was to compare the effects of 3 stocking rates, high stocking rate (HSR; 20 goats/ha), medium stocking rate (MSR; 15 goats/ha), and low stocking rate (LSR; 10 goats/ha), on gastrointestinal (GI) nematode infections and productive responses of Cashmere goats grazing such pastures. Treatments were replicated twice on 6 paddocks sown with and and with a high presence of the native grass . The experiment lasted 3 grazing seasons (from spring to autumn). Pastures were sampled for sward height and botanical and proximate composition. Body weight and BCS changes of goats were monitored and GI nematode infections were assessed by fecal egg counts (FEC). The established treatments resulted in lower mean sward height in the HSR than in the MSR and LSR (9.6, 11.5, and 14.4 cm, respectively; < 0.001). Pasture botanical composition and nutritive quality did not differ between treatments. The mean FEC of does across the 3 grazing seasons were greater ( < 0.05) in the HSR than in the LSR. spp., , and were the most prevalent nematode species identified in coprocultures. Does showed more favorable ( < 0.001) BW and BCS changes in the LSR than in the MSR and HSR (-14, -30, and -52 g/d and -0.1, -0.3, and -0.7 BCS units [scale 1 to 5], respectively). Greater ( < 0.001) kids' BW gains were observed in the LSR and MSR (average 94 g/d) compared with the HSR (70 g/d). Inversely, kid output per unit land area was greater in the HSR than in the MSR and LSR (320, 258, and 192 kg∙ha∙yr, respectively; < 0.001), whereas daily kids' BW gains per hectare were greater ( < 0.001) in the HSR and MSR (average 1.37 kg∙d∙ha) compared with the LSR (0.98 kg∙d∙ha). A medium stocking rate of 15 goats/ha could represent the best compromise between animal health, performance, and productivity per unit land area in this type of upland pastures, but stricter controls of parasite levels during the grazing season would be necessary to avoid production losses, unless alternative nutraceuticals are provided.

Application of long-chain alcohols as faecal markers to estimate diet composition of horses and cattle fed with herbaceous and woody species.

Utilization of long-chain alcohols (LCOH) as diet composition markers in horses and cattle was assessed in a study conducted with 12 mature crossbreed mares (385±47 kg BW) and six adult non-lactating cows (499±36 kg BW) of Asturiana de los Valles breed. The LCOH data were combined with alkane and long-chain fatty acid (LCFA) data to test the applicability of combining these markers to estimate diet composition. Animals were randomly divided into groups of three animals and received a daily total amount of 1.0 kg dry matter/100 kg BW of diets composed of different proportions of ryegrass (Lolium perenne) and woody species (Ulex gallii and heather). Diet composition was estimated from even-chain LCOH (C(20)-OH to C(30)-OH) combined or not with alkane (C(25)-C(31) and C(33)) and/or LCFA (C(22)-FA to C(28)-FA, C(30)-FA, C(32)-FA and C(34)-FA) concentrations in diet components and faeces by least-squares procedures, using marker faecal concentrations uncorrected for incomplete faecal recovery (FR0) or corrected using mean recoveries across diets within animal species (FR1). Results showed large differences between plant species in their LCOH profiles, and that these markers offered additional discriminatory information to that provided by alkanes and LCFA. The LCOH markers were incompletely recovered in the faeces of both animal species. In cattle, LCOH FR tended to increase with carbon-chain length in a linear manner in both diets (P < 0.001), whereas in horses overall data showed a curvilinear relationship between these variables. Combination of LCOH, LCFA and alkanes resulted in more accurate diet estimates. Correction of faecal LCOH concentrations to incomplete FR led to more accurate diet composition estimates in both animal species. Results obtained in this study suggest the usefulness of LCOH markers combined with alkanes and LCFA to estimate diet composition of horses and cattle grazing mixed grassy-woody plant communities.

Anthelmintic effect of heather in goats experimentally infected with Trichostrongylus colubriformis.

The effects of heather (composed primarily of Calluna vulgaris with a smaller content of Erica umbellata and Erica cinerea) consumption on the establishment of incoming infective larvae (experiment 1, preventive treatment) and an adult worm population (experiment 2, curative treatment) were investigated in Cashmere goats experimentally infected with Trichostrongylus colubriformis. In experiment 1, 12 castrated male goats were divided into two groups: heather-supplemented vs. non-supplemented animals. After 2 weeks of adaptation to the diet, all goats were experimentally infected per os with 6,000 T. colubriformis third-stage larvae. Three weeks post-infection, the goats were slaughtered, and worm counts as well as female worm fecundity and development were determined. Heather consumption was associated with a close to significant (P=0.092) reduction (mean 14 %) in larvae establishment. No effect on fecundity was observed, but the length of female worms in supplemented goats was greater (P<0.001). In experiment 2, 15 non-lactating does were experimentally infected with 6,000 T. colubriformis third-stage larvae. At 6 weeks post-infection, three groups were established: control, heather-supplemented and heather-supplemented with polyethylene glycol. Individual faecal nematode egg output was measured twice weekly to assess gastrointestinal nematode egg excretion. The goats were slaughtered 5 weeks after heather administration (11 weeks post-infection), and worm counts as well as female worm fecundity and development were subsequently determined. Heather administration was associated with a significant (P<0.001) decrease (between 47 and 66 % compared with control group) in egg excretion from 45 to 76 days post-infection. Although worm counts and female fecundity were lower in supplemented goats, no significant differences were observed. Overall, the results showed a reduction in T. colubriformis larvae establishment and a decrease in nematode egg excretion when heather was administered in experimentally infected goats. The heather plus polyethylene glycol treatment reduced nematode egg excretion levels at the same proportion as heather, thereby suggesting that the threshold of tannins required for an anthelmintic effect is most likely quite low.

In vitro effect of heather extracts on Trichostrongylus colubriformis eggs, larvae and adults.

This study was carried out to evaluate the in vitro effects of different heather species on Trichostrongylus colubriformis eggs, larvae and adult worms, and obtain scientific evidence to attribute these effects to the action of their phenolic compounds and/or tannins. Total phenolic extracts of three heather species (Calluna vulgaris, Erica cinerea, and Erica umbellata) and an equal mixture of these three extracts were tested in vitro in the three development stages of T. colubriformis using an egg hatching assay (EHA), larval exsheathment inhibition assay (LEIA), and adult motility inhibition assay (AMIA). The egg hatching rate was measured after incubation with heather extracts for 48 h at 25°C. Infective third-stage larvae (L3) were incubated for 3h at 25°C with heather extracts. The evolution of artificial exsheathment over time was measured with repeated observations at 20-min intervals for 60 min. Adult worms were obtained from one donor goat and incubated with the extracts at 37°C for 5 days in 48-multiwell plates. Worm motility was measured at 0, 19, 24, 43, 48, 67, 72, 96 and 115 h after the beginning of the experiment. The extracts were tested at concentrations of 75, 150, 300, 600 and 1,200 µg/ml. All extracts significantly (P<0.001) inhibited egg hatching and the effect was dose dependent. All extracts inhibited or delayed the exsheathment of T. colubriformis L3, and the effect was dose dependent for C. vulgaris. Incubation with heather extracts induced a reduction in adult worm motility compared to control, although significant (P<0.05) differences were only found at the highest concentrations. Additional studies showed that purified tannins of the same heather species disturbed T. colubriformis larval exsheathment. All these results confirm the anthelmintic properties of heather against T. colubriformis, and suggest that not only tannins but also some other phenolic compounds might be involved.

In vitro effect of heather (Ericaceae) extracts on different development stages of Teladorsagia circumcincta and Haemonchus contortus.

The aim of the present study was to evaluate the in vitro effects of heather (Ericaceae) phenolic extracts on the abomasal nematodes Teladorsagia circumcincta and Haemonchus contortus. Extracts of three heather species (Calluna vulgaris, Erica cinerea, Erica umbellata and a balanced mixture of all three) were tested in vitro on different development stages of T. circumcincta (eggs, infective larvae and adult worms) and H. contortus (eggs and infective larvae) using an egg hatching assay (EHA), a larval exsheathment inhibition assay (LEIA) and an adult motility inhibition assay (AMIA). The egg hatching rate was measured after incubation with heather extracts for 48 h at 25 °C. Ensheathed infective larvae were incubated for 3h at 20 °C with heather extracts. Artificial exsheathment was induced in vitro by adding hypochloride solution to the larval suspension. The progress of exsheathment over time was measured by repeated observations at 10-min (T. circumcincta) and 20-min (H. contortus) intervals for 60 min. Adult T. circumcincta worms were obtained from two donor goats and incubated with the extracts at 37 °C for 3 days in 48-well multiwell plates. Worm motility was measured at 0, 19, 24, 43, 48, 67 and 72 h. The extracts were tested at concentrations of 75, 150, 300, 600 and 1200 µg/mL. Incubation with E. cinerea, E. umbellata and mixed heather extracts had a significant (P<0.01) dose-dependent effect on T. circumcincta egg hatching. H. contortus egg hatching was significantly (P<0.01) inhibited only by the E. cinerea extract. All extracts had a significant (P<0.01) dose-dependent effect on the exsheathment of T. circumcincta and H. contortus infective larvae. The incubation with all heather extracts induced a reduction in adult T. circumcincta motility compared to the control, although significant (P<0.05) differences were only found at the highest concentration (1200 µg/mL). The effect of the mixed extract was significant at all concentrations and significant effects were also observed for C. vulgaris and E. umbellata at 600 µg/mL. These results show anthelmintic properties of heather phenolic extracts against T. circumcincta and H. contort, thus confirming observations from previous in vivo studies.

Effect of the consumption of heather on incoming larvae and established population of Teladorsagia circumcincta in experimentally infected Cashmere goats.

This study was performed in Cashmere goats that were experimentally infected with Teladorsagia circumcincta to investigate the effects of heather consumption on the establishment of incoming infective larvae (experiment 1) and on an adult nematode population (experiment 2). In experiment 1, 24 non-lactating goats were divided into 2 groups: heather-supplemented vs. non-supplemented. After 2 weeks of adaptation to the diet, all of the goats were experimentally infected with 6000 infective larvae of T. circumcincta. Twelve animals (6 controls and 6 supplemented with heather) were slaughtered at 6 days and at 3 weeks post-infection (pi). After slaughter, the worms were counted and the female worm fecundity and development were determined. Heather consumption was associated with a significant reduction in larval establishment at 6 days (P=0.033) and at 3 weeks (P=0.041) pi. No differences in worm counts between the slaughter times were found. In the goats slaughtered at 3 weeks pi, the number of eggs in utero and length of the female worms were significantly (P<0.001) lower than those of control group. In experiment 2, 24 non-lactating goats were experimentally infected with 10,000 T. circumcincta infective larvae daily for 5 consecutive days (total infection of 50,000 larvae). After 3 weeks, 2 groups were established: control and heather-supplemented. The faecal egg output of each animal was measured at 2-days interval during the experimental period. The goats were slaughtered after 3 weeks of heather administration for parasitological studies. Heather administration was associated with a significant decrease in egg excretion between 25 and 29 days pi. The worm counts were similar in both groups, but the female length and fecundity were significantly (P<0.001) lower in supplemented goats. These results show that heather consumption reduces the establishment of T. circumcincta larvae in goats and the development and fecundity of female adult parasites.

Evaluation of long-chain alcohols as diet composition markers in goats grazing heathland areas.

An experiment was conducted to assess the potential of long-chain alcohols (LCOH), in alternative or combined with alkanes and long-chain fatty acids (LCFA), as faecal markers to estimate the diet composition of goats grazing heathland vegetation with associated improved pastures. A total of seven diets were offered across the grazing season. The diets were composed of mixtures of herb species (Lolium perenne and Trifolium repens) and woody species (Erica spp., Calluna vulgaris and Ulex gallii) in an attempt to simulate diet selection of goats on these complex vegetation areas. The diet composition was estimated using LCOH markers alone or combined with alkanes, LCFA and alkanes+LCFA, by least square optimization procedures. The data showed large differences between plant species in their LCOH profile. Generally, plant species showed higher LCOH concentrations than those of alkanes and lower than LCFA markers. Faecal recovery of LCOH was incomplete and increased in a linear manner (P < 0.001) with the carbon-chain length, and was influenced by diet composition and its digestibility. The diet composition estimates based on LCOH alone were more accurate (P < 0.05) than those using alkanes or LCFA alone. Results showed that the combination of LCOH with alkanes, LCFA and alkanes+LCFA resulted in more accurate (P < 0.05) estimates of diet composition, indicating that LCOH provided different discriminatory information to that of alkanes and LCFA, helping in the discrimination of the plant species used in this experiment. Results indicate that correction of faecal LCOH concentrations to incomplete faecal recovery is necessary to obtain more accurate estimates of diet composition. Nevertheless, it seemed that the use of a less accurate recovery correction on LCOH markers had a lower impact on the accuracy of estimates than that of alkanes and LCFA.

Diet selection and performance of cattle and horses grazing in heathlands.

As the number of horses is steadily increasing in Cantabrian less-favoured areas, mostly occupied by nutritionally poor heathland communities, the objective of this research was to study and compare diet selection and performance of crossbred horses and beef cattle (Asturiana de los Valles breed) grazing these areas during the summer. A total of 20 cows (seven lactating their calves and thirteen dry) and 20 mares (eight lactating their foals and twelve dry) were managed during 3 years on a heathland area from June to September and October. The proportion of grass (mostly Pseudarrhenatherum longifolium) and heather (Erica umbellata, E. cinerea and Calluna vulgaris) in the diet selected by cows and mares was estimated in two occasions (July and September) each year using the alkane markers. All animals were weighed at the beginning, middle and end of the summer grazing season. Mares selected heath grasses and rejected heather species more than did the cows (P < 0.001), particularly in early summer (0.85 v. 0.65 herbage proportion in July; 0.63 v. 0.55 in September). Lactating state did not affect diet composition. Mares achieved more favourable (P < 0.001) body weight (BW) changes than cows, but there was also an interaction with season (P < 0.001). From June to August, cows lost BW, being the daily changes (in percentage of initial BW) -0.15%/day in lactating and -0.05%/day in dry cows, whereas both lactating and dry mares gained BW (0.16 and 0.12%/day, respectively). From August to October, lactating cows and mares lost more BW (P < 0.01) compared with their non-lactating counterparts (-0.19 v. -0.10%/day in cows, -0.14 v. -0.05%/day in mares). With regard to the offspring, BW gains between June and August were similar in calves and foals (0.83 and 0.90%/day, respectively), but thereafter calves achieved higher (P < 0.05) BW gains than foals (0.37 v. 0.16%/day). It is concluded that the low nutritive quality of these heathlands restricts, both cattle and horse performance, even during short summer grazing season, being more penalized lactating animals, especially the cows. Although calves were able to maintain acceptable growth rates, foals showed reduced ones during the second half of the grazing season. Other plant communities with better nutritive quality should be provided to assure replenishment of body reserves in dams, and enhance offspring gains to maintain sustainable grazing systems with productive herds of cattle and horses in these heathland areas.

Length of concentrate finishing affects the fatty acid composition of grass-fed and genetically lean beef: an emphasis on trans-18:1 and conjugated linoleic acid profiles.

Intensively finishing cattle on a high-grain diet is generally used to enhance marbling, whereas extensively finishing on grass is known to provide improved muscle fatty acid profiles. The objective of this study was to evaluate to what extent intensive concentrate finishing (0, 1 or 2 months) can be combined with forage feeding without negatively affecting the fatty acid profile of genetically lean animals. Bulls from the 'Asturiana de los Valles' breed were reared under grazing conditions with/without final finishing on a barley-based concentrate: 0 months (control; n=7), 1 month (n=10) and 2 months (n=7). Yearling bulls were slaughtered commercially at an average live weight of 516±9.8 kg. Increasing the finishing time on concentrate significantly increased the saturated and monounsaturated fatty acids, whereas polyunsaturated fatty acids (PUFAs) tended to decrease and it was not possible to increase the long-chain PUFA content in muscle tissue of this breed. An increase was observed for total trans-18:1 (average 5.5% with grain v. 3.7% for grass). The 11t-18:1/10t-18:1 ratio was significantly higher in grass-fed (average 8.1) compared with grain-finished animals (average 1.1). Grass or limited concentrate finishing reduced the n-6/n-3 ratio in muscle tissue (average 3.6 for 0 and 1 month, and 4.9 for 2 months on grain finishing). The beef was within or close to the recommended values for human consumption (i.e. polyunsaturated/saturated>0.45, n-6/n-3<4.0), and total trans-FA content was low. However, finishing increased the content of undesirable trans-18:1 and conjugated linoleic acid isomers, particularly after 2 months, whereas grass finishing was judged to provide a healthier beef fatty acid profile.

Eating quality of beef from biotypes included in the PGI "Ternera Asturiana" showing distinct physicochemical characteristics and tenderization pattern.

Different biotypes of the Protected Geographical Indication (PGI) "Ternera Asturiana" were studied to determine if their differences in physicochemical characteristics and tenderization pattern during maturation (3 to 21 days) had an effect on the consumer evaluation of beef palatability. Biotype affected significantly pH, water holding capacity, chemical composition (P < 0.001) and meat lightness (P < 0.05). Ageing time affected significantly (P < 0.05) colour, meat toughness and sensory attributes in a different way within each biotype. Multivariate analysis showed two different meat groups: 1) meat from mh-genotypes, characterized by high juice losses, lightness (L*), protein content and high sensory acceptability at intermediate (7 and 14 days) ageing times; 2) meat from rustic (AM) breed and biotypes free of myostatin mutation (AV (+/+) and AV x AM), showing higher intramuscular fat, myoglobin content, and instrumental toughness and requiring longer storage times (21 days). This should be taken into account for the proper post-mortem management and commercialization of each product to achieve its best sensory quality.

Effect of breed body size and the muscular hypertrophy gene in the production and carcass traits of concentrate-finished yearling bulls.

To examine the extent of the effect of muscular hypertrophy character in beef of northern-Spanish breeds, animal performance and carcass characteristics of 152 finishing steers from 5 genotypes were studied: 32 yearling bulls from a rustic Asturiana de la Montaña (AM) breed, 96 yearling bulls from Asturiana de los Valles (AV) breed, divided in 3 groups depending on the presence of the gene responsible for double-muscling (i.e., 32 AV mh/mh, 32 AV mh/+, 32 AV +/+), and 24 yearling bulls from AM x AV cross were used. Each genotype was composed of 8 animals per year (4 animals per pen) for 4 yr, except for the AM x AV genotype, which was only evaluated in the last 3 yr of the experiment. All animals were fed indoors with concentrate meal and barley straw ad libitum. Average daily gains in AV animals (1.41 kg/d) were greater (P < 0.01) than in AM (1.12 kg/d), whereas AM x AV were intermediate (1.29 kg/d) to these. No significant differences (P = 0.604) in ADG were found among the 3 AV genotypes. Longer fattening periods (P < 0.001) were taken for AM animals to reach acceptable BW at slaughter. Double-muscled animals (AV mh/mh) were found to have the best feed efficiencies when expressed as G:F (P < 0.001). However, residual feed intake calculated on a daily basis showed a greater efficiency in AV mh/mh and AM than in other genotypes. Carcasses from double-muscled animals had greater BW, yield, conformation and compactness index, and less fat cover than the other genotypes (P < 0.001). Carcasses from AM breed were the lightest and had the worst conformation, whereas those from AM x AV generally presented intermediate characteristics between AV and AM. Double-muscled animals had the greatest LM weight and area. The sixth-rib dissection revealed a greater percentage of muscle (84.6%) and decreased percentages of subcutaneous fat (1.1%), intermuscular fat (4.7%), bone (8.5%), and other tissues (1.2%) in AV mh/mh compared with other genotypes. Water-holding capacity was greatest in AM and least in AV mh/mh. In conclusion, double-muscled AV bulls would provide the greatest economic returns at intensive feeding systems because of their greater efficiency, reduced feeding costs, greater carcass weight and conformation, and greater lean yields, though some LM characteristics (reduced fat content and water-holding capacity) could negatively affect the sensory attributes of the meat compared with other genotypes with greater fatness.

Assessment of very long-chain fatty acids as complementary or alternative natural fecal markers to n-alkanes for estimating diet composition of goats feeding on mixed diets.

This study aimed to assess the use of very long-chain fatty acids (VLCFA) as an alternative or a complement to n-alkane markers for estimation of diet composition of goats fed 7 different diets, composed of different proportions of herbaceous (Lolium perenne and Trifolium repens) and heathland woody species (Erica umbellata, Erica cinerea, Calluna vulgaris, Erica arborea, and Ulex gallii), in a metabolism study. Diet composition was estimated from VLCFA (i.e., C(22) to C(34)) and alkane (i.e., C(25) to C(33)) concentrations in diet and feces, by least squares procedures. For all plant species VLCFA concentrations were greater than their alkane concentrations, especially for the herbaceous species and U. gallii. In general, fecal recovery of both markers was incomplete and increased in a curvilinear (P < 0.001) fashion with carbon-chain length. The plants comprising the diets had a significant effect (P < 0.001) on fecal recovery of VLCFA and alkanes. Diet composition estimates based on VLCFA alone were less accurate (P = 0.013) than those obtained using alkanes alone. Combination of VLCFA and alkane data resulted in the most accurate (P < 0.05) estimates, indicating an increase on the discriminatory power among plant species. Use of uncorrected fecal marker concentrations provided the poorest estimates of diet composition, and use of individual recovery data and mean fecal recovery data of the dietary treatment yielded the most accurate ones. Results obtained in this study show that VLCFA have potential to be used as diet composition markers along with alkanes.

Natural breeding with bulls experimentally infected with Neospora caninum failed to induce seroconversion in dams.

Four bulls and 56 heifers seronegative to Neospora caninum were used to determine the feasibility of venereal transmission in bovine neosporosis under natural conditions. Bulls were experimentally infected with 10(8) live N. caninum tachyzoites. Two of them with the Nc-1 isolate and the other two with the Nc-Spain-7 isolate. After 13 months of initial infection, each bull was re-infected with the same isolate and dose. The experiments were carried out from March to September during 2006 and 2007 where groups of cyclic heifers were naturally mated by the experimentally infected bulls. In year 2006, two bulls infected with different N. caninum isolate serviced 12 heifers each. In year 2007, the same bulls serviced the same heifers a second time (now primiparous) and six new heifers were also added to each group. In addition, the other two bulls serviced 10 additional heifers each. Experimental animals were monitored for 30 weeks and serum samples were collected weekly and fortnightly in years 2006 and 2007, respectively to evaluate the presence of specific antibodies to N. caninum. Experimentally infected bulls showed a significant increase of specific IgG antibodies from 13 (Nc-SP-7) and 21 (Nc-1) days post-infection. Serum IgG antibody responses of individual animals were similar in kinetics but slightly different in magnitude. Serum samples from heifers were all negative. Pregnant rates were 100% in heifers and 91% in primiparous animals. Calves did not show precolostral specific antibodies to N. caninum. Venereal transmission of bovine neosporosis under natural grazing conditions is unlikely to occur.

Effects of re-infection with Neospora caninum in bulls on parasite detection in semen and blood and immunological responses.

Three bulls with experimentally induced primary infection with Neospora caninum were re-infected intravenously with 10(8) live N. caninum tachyzoites of the NC-1 isolate at 300 days post-infection to investigate the presence of N. caninum in semen and blood, and the associated immune responses. In parallel, three bulls with experimentally induced primary infection with N. caninum and three non-infected bulls were also monitored. Re-infected and infected bulls showed an intermittent presence of N. caninum DNA in semen with a parasite load ranging from 0.1 to 15.6 (mean 4.4) and 0.1 to 11.1 (mean 4.1) parasites/ml, respectively. Re-infected bulls showed significant and persistent serum-specific IgM and IgG antibody responses. Specific IgG levels were detected in seminal plasma of all infected bulls, but the magnitude of the response was significantly higher in re-infected rather than in chronically infected animals. The mean specific IFN-gamma levels in re-infected bulls were significantly increased as early as 3 and 7 days after experimental infection when compared to bulls in other groups. This study showed that the intermittent presence and parasite load of N. caninum in the semen of re-infected bulls is very similar to that reported in chronically infected animals. The protozoa could not be isolated from BALB/c nu/nu mice inoculated with PCR-positive semen samples and inseminated heifers with pooled semen samples did not show seroconversion. Plasma IFN-gamma level seems to be a good indicator of a recent N. caninum infection.

Prediction of the fatty acid composition of beef by near infrared transmittance spectroscopy.

The intramuscular fat content and composition influence consumer selection of meat products. A study predicting the fatty acid (FA) profile of ground beef from the Longissimus thoracis of yearling bulls (n=100) using near infrared transmittance spectroscopy (NIT) was conducted. The samples were scanned using an Infratec 1265 Meat Analyzer which operates in transmittance mode from 850 to 1050nm. NIT technology was able to accurately predict (R(CV)(2) over 0.76) some prominent FAs such as C14:0, C16:0, C16:1cis9, C17:0, C18:1cis9 and C18:1cis11, and minor FAs like C13:0, C15:0, C17:1cis9 and C18:1cis13. When studying FA groups, NIT spectra were able to accurately predict saturated (R(CV)(2)=0.837), branched (R(CV)(2)=0.701) and monounsaturated (R(CV)(2)=0.852) FAs. In addition, NIT spectra provided useful information on the contents of conjugated linoleic acids (CLA) in beef. These results show the potential of NIT technique as a rapid and easy tool to predict the major FAs in beef, especially those located in triglycerides.

Is the anthelmintic effect of heather supplementation to grazing goats always accompanied by anti-nutritional effects?

To test the hypothesis that the beneficial anthelmintic effect of consuming moderate amounts of tannins may not always be accompanied by anti-nutritional effects in goats, two experiments were conducted. In the first, 48 Cashmere goats were randomly assigned to two treatments: supplementation with tannin-containing heather (6.4% total tannins) and non-supplementation. All goats grazed continuously from May to September under farm conditions in a mountainous area of northern Spain. The mean percentage of heather incorporated into the diet of the supplemented animals was 29.1%. Supplementation reduced the mean number of nematode eggs in faeces (P < 0.001) and the goat mortality rate (P < 0.05). The rumen ammonia concentration was markedly reduced in the goats receiving the heather supplement (160 v. 209 mg/l; P < 0.01), while volatile fatty acid (VFA) concentrations were significantly greater (63.0 v. 53.6 mmol total VFA/l; P < 0.05). The heather-supplemented goats also showed a lower loss of live weight (P < 0.01) and body condition score (P < 0.001). In the second experiment, batch cultures of rumen microorganisms with rumen fluid from nine goats whose diet included 29% heather - or not, were used to incubate three substrates (pasture, pasture + heather and pasture + heather + polyethylene glycol) to investigate in vitro ruminal fermentation. Differences (P < 0.01) among substrates were observed in terms of dry matter disappearance (DMD), in vitro true substrate digestibility (ivTSD), gas production and ammonia concentration, the greatest values always associated with the pasture substrate. Cultures involving rumen inoculum derived from goats receiving the heather-containing diet showed slightly lower DMD (46.9 v. 48.5 g/100 g; P < 0.05), ivTSD (64.6 v. 65.9 g/100 g; P < 0.10) and gas production (105 v. 118 ml/g; P < 0.001) values, but much greater total VFA concentrations (48.5 v. 39.3 mmol/l; P < 0.05), and suggest that the efficiency of ruminal fermentation in these animals was probably improved. Together, the results support the absence of a clear nutritional cost counteracting the beneficial anthelmintic effect of supplementing the diet of grazing goats with tannin-containing heather.

Grazing behaviour and performance of lactating suckler cows, ewes and goats on partially improved heathlands.

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.

Experimental neosporosis in bulls: parasite detection in semen and blood and specific antibody and interferon-gamma responses.

AIM: To investigate the presence of Neospora caninum in semen and blood, and the development of specific antibody and interferon-gamma (IFN-gamma) 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-gamma 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-gamma 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.