Svenja Marquardt

In vitro indications for favourable non-additive effects on ruminal methane mitigation between high-phenolic and high-quality forages

Feeding plants containing elevated levels of polyphenols may reduce ruminal CH₄ emissions, but at the expense of nutrient utilisation. There might, however, be non-additive effects when combining high-phenolic plants with well-digestible, high-nutrient feeds. To test whether non-additive effects exist, the leaves of Carica papaya (high in dietary quality, low in polyphenols), Clidemia hirta (high in hydrolysable tannins), Swietenia mahagoni (high in condensed tannins) and Eugenia aquea (high in non-tannin phenolics) were tested alone and in all possible mixtures (n 15 treatments). An amount of 200 mg DM of samples was incubated in vitro (24 h; 39°C) with buffered rumen fluid using the Hohenheim gas test apparatus. After the incubation, total gas production, CH₄ concentration and fermentation profiles were determined. The levels of absolute CH₄, and CH₄:SCFA and CH₄:total gas ratios were lower (P< 0·05) when incubating a combination of C. papaya and any high-phenolic plants (C. hirta, S. mahagoni and E. aquea) than when incubating C. papaya alone. Additionally, mixtures resulted in non-additive effects for all CH₄-related parameters of the order of 2-15 % deviation from the expected value (P< 0·01). This means that, by combining these plants, CH₄ in relation to the fermentative capacity was lower than that predicted when assuming the linearity of the effects. Similar non-additive effects of combining C. papaya with the other plants were found for NH₃ concentrations but not for SCFA concentrations. In conclusion, using mixtures of high-quality plants and high-phenolic plants could be one approach to CH₄ mitigation; however, this awaits in vivo confirmation.

Plant species selection by free-ranging cattle in southern Bolivian tropical montane forests

The frequency of selection of functional groups and plant species by free-ranging cattle foraging in a diverse environment and its changes during the dry and the following prehumid seasons were investigated using direct observations and bite counting. The study was conducted at two sites in the Bolivian-Tucuman montane forests in southern Bolivia, by including datasets of a total of 16 animals. Across both study sites and the entire observation period (May to October/November), the cattle were found to select a broad spectrum of plant species from different functional groups. However, just a limited number of species made up a considerable contribution to overall plant selection. The functional group of the graminoids was selected most frequently, but their contribution to plant selection decreased significantly from 63.5% of total bites in May to 15.9% in September/October, in accordance with a decrease in availability. Selection of woody plants (shrubs and tree parts, the latter mainly in the form of leaf litter and fruits) increased with time, reaching its peak at the beginning of the prehumid season, while the herbs showed a curvilinear pattern of selection which was highest in August. Plant species belonging to the functional groups of ferns, climbers and epiphytes were also selected by the cattle, but generally at low relative proportions. Plant selection might be influenced by temporal differences in nutritional quality and availability of the preferred plant species and functional groups. Sampling behaviour seems to be the most likely reason for the inclusion of a broad range of plant species with overall low contribution to plant selection.

Effect of individual Ayurveda plants and mixtures thereof on in vitro ruminal fermentation, methane production and nutrient degradability

In order to identify new ways to mitigate methane emissions from ruminants, six medicinal plants, Achyranthes aspera, Azadirachta indica, Andrographis paniculata, Helicteres isora, Tinospora cordifolia and Piper longum, were evaluated in vitro with respect to ruminal fermentation and methanogenesis. A three-stage approach with n = 6 per treatment was applied. Two 24-h Hohenheim gas test experiments were performed by incubating the plants first as sole substrate and then added to a basal diet (10 g/kg diet DM). Finally, in a 10-day Rusitec experiment, A. paniculata, P. longum and T. cordifolia were supplemented individually and in all binary combinations to a basal diet (25 g/kg DM). Provided as sole substrate, all plants, except P. longum, decreased methane and carbon dioxide production (P < 0.05), and reduced the methane : short-chain fatty acid ratio (P < 0.05) in the Hohenheim gas test. In Rusitec, none of the individual supplements decreased methane production. The combination of A. paniculata with P. longum as a supplement was effective in mitigating the methane : carbon dioxide ratio and simultaneously maintaining feeding value. In conclusion, all medicinal plants incubated as sole substrate, except P. longum, possess anti-methanogenic properties, especially T. cordifolia, A. indica and H. isora. When supplemented at the levels investigated, they were mostly neutral with respect to rumen fermentation and nutrient digestion. Combining A. paniculata with P. longum mitigated methane without side effects on general ruminal fermentation. Further investigations, carried out in vivo, will demonstrate how useful this plant combination is in ruminant nutrition.

Plant Selection and Performance of Two Cattle Types and Camels on Semiarid Rangelands in Kenya

ABSTRACT Plant selection pattern and performance of lactating cattle and camels were compared on semiarid savanna rangelands in Kenya in the rainy season (RS) and a transition period (TP) between the RS and the main dry season. It was further evaluated whether supplementation with rumen-degradable protein (RDP) had an effect on these parameters. In both seasons, two cattle types (local ‘Pokot’ cattle and Guernsey × Boran crossbreds) and camels were used, with six females per treatment group (supplemented and nonsupplemented) each (n = 72 animals in total). The experimental periods consisted of 8–10 d of adaptation and 36–40 d of data and sample collection. The diet selected by the cattle types was similar and consisted almost exclusively of grasses. The camel diet consisted mainly of herbs and shrubs with higher contributions of woody plants in the TP than in the RS. Forage from woody plants overall made up a higher proportion of the diet, which was also reflected by a longer browsing time (overall and in the TP) of the supplemented camels compared with the nonsupplemented camels. This result indicates that supplementation of browsers like camels with RDP can be used to increase the intake of forage from woody plants rich in plant secondary compounds, which could be an effective measure for managing rangeland to limit bush encroachment. Overall, no seasonal differences in milk yield were found for the camels and Pokot cattle, but crossbreds had a lower yield in the TP compared with the RS. Overall, the cattle had higher milk fat content than the camels while the camels had slightly higher protein content. Supplementation had no effect on milk yield and composition. The results of diet selection and performance (milk yield) reflect the advantage of camels in arid rangelands.

Foraging Behavior of Criollo vs. Brahman × Criollo Crossbreds in the Bolivian Chaco: Case Study

ABSTRACT Diet selection and performance of Criollo Chaqueño and Brahman × Criollo Chaqueño were studied in three seasons in the dry forests of the Bolivian Chaco using direct observations. During the dry season (DS) and the rainy season (RS), the Criollo cattle diet consisted of a higher proportion (P < 0.05) of woody plants compared with the crossbreds, while the crossbreds included a higher proportion of grasses. Leaf litter was selected in the DS by Criollos but almost not by crossbreds (P < 0.05; 23% and <1% of diet selection, respectively). Season (P < 0.001) had an overall effect on body weight change with a loss of weight in the DS. However, between the DS and the RS the bodyweight of the Criollos increased (P < 0.05),whereas it did not differ (P > 0.05) for the crossbreds. Other than for the Criollos, the body weight of the crossbreds decreased (P < 0.05) from the DS to the transition period. Especially during the DS, Criollos made more use of forage resources from shrubs and trees and thus, seem to be better adapted to year-round forest grazing compared with the crossbreds.

In vitro bioactivity of various pure flavonoids in ruminal fermentation, with special reference to methane formation

Polyphenols, like flavonoids, have been investigated when present in intact plants or in extracts as methane mitigating dietary supplements in ruminants. The aim of the present study was to examine pure compounds in a short-term in vitro experiment using the Hohenheim Gas Test method. We focused on the group of the flavonoids and tested which of them had the potential to mitigate methane without negatively affecting ruminal fermentation. Eight flavonoids were tested: epicatechin, luteolin-7-glucoside, quercetin, and isoquercetin in Experiment 1; catechin, gallocatechin, epigallocatechin, and epigallocatechin gallate in Experiment 2. Tannic acid, no flavonoid but a phenolic acid with known methane mitigating properties, served as positive control, and the unsupplemented basal diet as negative control. In both experiments, each of these compounds (including tannic acid) was tested at dosages of 0.5, 5.0, and 50.0 mg/g basal diet dry matter (DM) in four runs each. Gallocatechin, tannic acid, and epigallocatechin gallate (50 mg/g DM) lowered fermentation gas formation and in vitro organic matter digestibility relative to the negative control (Experiment 2). Apart from tannic acid, epicatechin, quercetin, isoquercetin, and luteolin-7-glucoside (5 and 50 mg/g DM) reduced the amount of CH4 produced in relation to total gas produced (Experiment 1). The incubation fluid ammonia concentration was decreased with luteolin-7-glucoside and tannic acid (50 mg/g DM). From the flavonoids tested especially luteolin-7-glucoside seems to have a similar potential as tannic acid to mitigate methane and ammonia formation during ruminal fermentation in vitro, both favourable in environmental respect. These results need to be confirmed in live animals.

Fatty acid profile of ghee derived from two genotypes (cattle-yak vs yak) grazing different alpine Himalayan pasture sites

The fatty acid (FA) profile of ghee produced from milk of cattle–yak hybrids grazing five mountain pasture sites along a high-alpine transhumance route in Nepal was analysed. Pastures differed in altitude above sea level (2600–4500 m), time period of being grazed and phytochemical composition of the swards. Additionally, a comparison of ghee from purebred yak and hybrid was performed, with samples produced at two of the sites. Pasture site had a strong effect on almost all FAs. Proportions of oleic, linoleic and α-linolenic acid in ghee were smallest on the highest pasture at 4500 m where the largest condensed tannin concentrations in the forages were found. No systematic site effects were found for c9,t11 conjugated linoleic acid and total polyunsaturated FAs. Ghee produced from the hybrids’ milk was richer in major functional FAs such as α-linolenic and linoleic acid, while yak ghee contained more saturated FAs and eicosapentaenoic, docosapentaenoic and docosahexaenoic acids.

Response to high altitude grazing in metabolic traits and performance by yak crossbreds and yaks

Yaks (Bos grunniens) and yak crossbreds are kept in transhumant systems using different pastures along an altitudinal gradient in the Nepalese Himalayan Mountains. Yaks are known to be well adapted to cope with low oxygen partial pressure, low temperatures and the harsh mountain environment (Wiener et al., 2003), and the resulting energy deficiency. Less information is available on the adaptive capabilities of yak crossbreds. Crossbreeding is a strategy to obtain higher milk yields especially by heterosis. In the Eastern Nepalese Himalayan Mountains, two different local breeds are used for crossbreeding. Bhelang bulls from near Tibet (Bos taurus genotype) are crossed with female yaks, and yak bulls are crossed with female Nepalese hill cattle (Bos indicus). Female crosses of cattle bulls × yak cows are locally called Dimjo chauries, while those which are produced using cows and yak bulls are called Urang chauries (Joshi, 1982). In order to compare the adaptive capacity of these two crossbred types with that of yaks, an experiment was conducted at two altitudes in the Taplejung District of Nepal.