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 200mg DM of samples was incubated in vitro (24h; 39oC) 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 confirmatio

Activity, Physiology and Milk Production of Yaks and Two Different Yak Crossbreds Grazing Himalayan Pasture Sites at 4700 m and 3000 m

Yaks (Bos grunniens) and crossbreds of yaks with different local cattle breeds are important for the livelihood of local herders in the Himalayas. They are often kept in a system of transhumance comprising the use of different pasture sites for grazing along an altitudinal gradient throughout the year. The animals are moved upwards to the high altitude pastures in spring/early summer and gradually moved downwards in late summer/autumn. Yaks are suitable for very high altitudes as they are especially adapted to low oxygen partial pressure, forage scarcity and cold and harsh environment (Wiener et al. 2003). However, yak-cattle crossbreds have an advantage in terms of milk yield due to heterosis and can utilize the lower winter pasture sites better than yaks. In the Taplejung District of Nepal, in the Kanchenjunga Conservation Area (KCA), two different yak crossbreds are most common. In the lower mountains of KCA, Nepalese common hill cattle (a Bos indicus genotype) are available and are crossed with yak bulls. In the higher mountain regions, closer to the Tibetan border, crosses of female yaks (called naks) with so-called Bhelang bulls of B. taurus genotype are produced. The aim of the study was to compare these crossbreds of yaks and cattle and relate them to yaks in terms of locomotive activity pattern, physiological responses and performance when grazing at two different altitudes along a transhumant route in the Himalayan Mountains

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 selectio

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

Abstract Feeding plants containing elevated levels of polyphenols may reduce ruminal CH 4 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 o C) with buffered rumen fluid using the Hohenheim gas test apparatus. After the incubation, total gas production, CH 4 concentration and fermentation profiles were determined. The levels of absolute CH 4 , and CH 4 :SCFA and CH 4 :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 CH 4 -related parameters of the order of 2 -15 % deviation from the expected value (P,0·01). This means that, by combining these plants, CH 4 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 NH 3 concentrations but not for SCFA concentrations. In conclusion, using mixtures of high-quality plants and high-phenolic plants could be one approach to CH 4 mitigation; however, this awaits in vivo confirmation