L. M. M. Ferreira

Grazing land management and biodiversity in the Atlantic European heathlands: a review

Atlantic heaths are semi-natural habitats of high biodiversity interest which once covered large areas of the Atlantic Region. Nowadays these heathlands are dramatically reduced in many countries although they still cover wide areas in the north-west Iberian Peninsula, especially in the poorest and most socially marginal areas that are frequently affected by wildfires. We review the role of livestock grazing as a sustainable management strategy for heathlands in Europe. We have worked on a generalized conceptual framework for the management of a resource of nutritional and environmental value by drawing together evidence from studies of the livestock and the community ecology of grazed plants and the associated fauna. Key factors that influence grazing impact, such as type of livestock (animal species and breed) and their management are discussed. Goats thrive better than sheep, and horses than cattle, when heathland vegetation is the predominant resource available. Regardless of the type of livestock species managed, the low nutritive value of this vegetation hinders the maintenance of productive groups of suckler dams with offspring through the grazing season. The nutritional requirements of livestock can be met by adding improved pasture areas to heathlands. Under that strategy, sheep have the best productive performance and cattle the poorest. Management of mixed flocks with goats can lead to a more efficient use of vegetation, improve productivity and develop a patchier habitat which supports a richer associated fauna. Overall the results indicate that the sustainability of livestock grazing in these marginal lands will be achieved if they are managed effectively according to the available vegetation and their effects on the biodiversity.

Understanding the equine cecum-colon ecosystem: current knowledge and future perspectives

Having evolved as a grazing animal, a horses digestive physiology is characterized by rapid gastric transit, a rapid but intense enzymatic digestion along the small intestine, and a long and intense microbial fermentation in the large intestine. The process of understanding and describing feed degradation mechanisms in the equine digestive system in general, and in the hindgut ecosystem in particular, is essential. Regardless of its importance for the nutritional status of the host, the significance of the cecum-colon ecosystem has not yet been fully understood, and few reports have focused deeply on the contribution of the hindgut microbial population to the nitrogen and energy requirements of the horse. Compared to ruminal activity, very little is known about hindgut ecosystem activity in the horse. Information concerning the metabolism of this microbial population and its requirements is lacking. The use of internal bacterial markers for quantifying microbial outflow in ruminants is widely reported. These techniques can be applied to cecum-colon microbial quantification, contributing to a better characterization of this ecosystem. It is likely wrong to believe that the optimization strategy in the hindgut is similar to what happens in the rumen - that is, to maximize microbial growth and, therefore, fermentation. If we consider the type of substrate that, in normal conditions, arrives in the hindgut, we can expect it to be nitrogen limiting, providing limited nitrogen-based substrates for microbial fermentation. In this review paper, we intend to gather existing information on the equine ecosystem and to provide future perspectives of research.

Estimation of feed intake by cattle using controlled-release capsules containing n-alkanes or chromium sesquioxide

An experiment was carried out to evaluate the utilization of the n-alkane technique and the chromium sesquioxide (Cr 2 O 3 )/acid insoluble ash (AIA) procedure to estimate feed intake of meadow hay by two breeds of cattle. The animals were housed in individual pens, and offered known amounts of meadow hay as the sole diet component. One group of 4 Barrosa cows (average weight, 457±24 kg) and another group of 4 Holstein–Friesian cows (average weight, 635±148 kg) were dosed with intra-ruminal controlled-release capsules (CRC) that contained alkane markers or Cr 2 O 3 in separate capsules. During intake estimation, meadow hay and faeces were sampled twice daily. There was no significant effect of grab sampling time on the meadow hay intake estimation, due to the fact that no differences were observed in the faecal marker concentrations. The mean real intakes, measured as the difference between the dry weight of feed offered each day and the dry weight of daily feed refusal, were 5·64 and 7·76 kg DM/day for Barrosa and Holstein–Friesian cows, respectively. For Barrosa cows the mean estimated intakes when using the CRC release rates documented by the manufacturer (MRR) were 5·66, 6·59 and 6·90 kg DM/day, using the Cr 2 O 3 /AIA procedure, C 31 [ratio ]C 32 and C 33 [ratio ]C 32 n-alkane pairs, respectively. For Holstein–Friesian cows the same markers gave values of 7·72, 8·51 and 8·95 kg DM/day, respectively. Mean daily intake estimation was improved when the release rate calculated as the reduction rate in CRCs payload performed in a additional experiment (CRR), was used. The differences from the real intake values, obtained using C 31 [ratio ]C 32 and C 33 [ratio ]C 32 alkane pairs, decreased from 950 and 1260 g/day to 140 and 420 g/day, respectively, for Barrosa cows and from 750 and 1190 g/day to 290 and 90 g/day for Holstein–Friesian cows. The intake estimation using the Cr 2 O 3 /AIA procedure was not affected by correcting the CRC release rate, because the release rates of both MRR and the CRR were similar. The results indicate that controlled-release capsules provide a uniform marker release in cattle, but also suggest that to obtain accurate estimates of intake, it is better to measure release rates within the context of particular experiments.

The potential of white‐rot fungi to degrade phorbol esters of Jatropha curcas L. seed cake

The potential of solid‐state cultivation, with three white‐rot fungi (Bjerkandera adusta, Ganoderma resinaceum and Phlebia rufa), to decrease phorbol esters concentration of Jatropha curcas L. was evaluated in this study. Incubation was conducted in 250 mL Erlenmeyer flasks without agitation at 28°C for 30 days. Phorbol esters were analyzed by reverse‐phase HPLC after an extraction procedure using dichloromethane. All fungi studied were able to decrease the concentration of phorbol esters, mainly B. adusta and P. rufa which significantly reduced (p<0.05) phorbol esters contents to non‐toxic levels. These results suggest that white‐rot fungi could be potentially used as a possible approach for the biological treatment of the oilseed cake.

Application of n-alkanes as diet composition markers in grazing/browsing goats and sheep: effect of using different faecal recovery corrections and plant species grouping approaches

The present study aimed to test the effect of applying different sets of n-alkane faecal recoveries and different plant species grouping approaches on the estimates of the diet selected by goats and sheep when grazing/browsing complex vegetation communities composed of mosaics of heather-gorse vegetation interspersed with patches of perennial ryegrass. The use of different sets of n-alkane faecal recoveries significantly affected the estimated proportions of most vegetation components in both animal species. The diet estimates were also significantly affected by the calculation approach: A1 (using all individual plant species); A2 (grouping plant species with similar n-alkane profile, with equal weighting within the group); and A3 (grouping plant species with similar n-alkane profile, with different weighting according to the botanical composition of the plot). There was a significant interaction between calculation approach (A) and faecal recovery sets (FR) on the resulting estimates of the Ericaceae species in the diet of goats and of all diet components in sheep. When using A1 approach, the estimated proportion of Agrostis capillaris in the diets was high and seemed to be overestimated, compared with its low availability (1.1% of total cover) in the field. However, the application of calculation approaches A2 and A3 gave lower dietary proportions of component D2 (Agrostis capillaris and Ulex gallii) and higher proportions of components D1 (Lolium perenne and Pseudarrhenatherum longifolium), D3 (Erica umbellata, Erica cinerea, Erica australis, Calluna vulgaris) and Erica arborea. These results indicate that the application of the n-alkane technique for estimation of the diet composition in field with complex vegetation conditions is sensitive to the use of faecal recovery corrections and to the grouping of possible dietary components.

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.

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.

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.

The influence of casein and urea as nitrogen sources on in vitro equine caecal fermentation.

To access the fermentative response of equine caecal microbial population to nitrogen availability, an in vitro study was conducted using caecal contents provided with adequate energy sources and nitrogen as limiting nutrient. Two nitrogen (N) sources were provided, protein (casein) and non-protein (urea). Caecal fluid, taken from three cannulated horses receiving a hay-concentrate diet, was mixed with a N-free buffer-mineral solution. The influence of four N levels (3.7, 6.3, 12.5 or 25 mg of N in casein or urea) was studied using the gas production technique. Total volatile fatty acids (VFA), NH3-N and gas production were measured after a 24-h incubation period. Microbial biomass was estimated using adenine and guanine bases as internal markers, and ATP production was estimated stoichiometrically. Microbial growth efficiency (YATP) and gas efficiency (Egas) were estimated. Fermentation with casein as the sole N source was generally characterized by lower total VFA, NH3-N, total gas production and higher acetate : propionate (A : P) ratio and YATP than with urea. Results herein presented indicate that, under these in vitro conditions, caecal microbial population does in fact use urea N, but less efficiently than casein in terms of microbial growth.

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.