Differential growth response of Rytidosperma species (wallaby grass) to phosphorus application and its implications for grassland management

Rytidosperma species (formerly Austrodanthonia) are native grasses common in temperate grasslands of southern Australia. Nine Rytidosperma species, Lolium perenne and Bromus hordeaceus were grown as microswards in pots in a glasshouse, and their growth response to six levels of applied P was measured. Shoot yield differed up to twofold between the highest‐ and lowest‐yielding Rytidosperma species. Some Rytidosperma species were slow growing with minimal ability to respond to increased soil P availability. However, three species, Rytidosperma duttonianum, Rytidosperma racemosum and Rytidosperma richardsonii, had a similar shoot yield to L. perenne. Species that grew well at high P also grew well at low P, except B. hordeaceus, which was the lowest‐yielding species at low P, but had among the highest yields at high P. No species showed evidence of P toxicity. The species exhibited a range in critical external P requirement (i.e. amount of P applied for 90% maximum yield). Among the fast‐growing Rytidosperma species, R. richardsonii was notable because it had a low critical external P (16·3 mg P pot^?1) and high agronomic P‐use efficiency (94·1 g DW g^?1 P applied). In contrast, R. duttonianum had a higher critical external P requirement (22·4 mg P pot^?1) and lower agronomic P‐use efficiency (85 g DW g^?1 P applied). It was concluded that it is important to know which Rytidosperma species are present in a grassland to understand how it may respond to P fertilization. The results help to explain the diverse opinions expressed about the productivity of pastures containing Rytidosperma species.     

Influence of plant growth and root architecture of Italian ryegrass (Lolium multiflorum) and tall fescue (Festuca arundinacea) on N recovery during winter

Nitrate () leaching is an environmental and health concern. In grazed pasture systems, leaching primarily occurs beneath animal urine patch areas due to high nitrogen (N) loading and the inability of pasture plants to capture all of this N. This study investigated the relative importance of plant growth and root architecture to recover soil N. Herbage N recovery, dry matter (DM) yield and root architecture, following injections of ¹⁵N‐enriched urea at different soil depths (5, 25 and 45 cm), were measured for Italian ryegrass (Lolium multiflorum Lam.) and tall fescue (Festuca arundinacea Schreb.) grown in soil monolith lysimeters (18 cm diameter × 70 cm depth) under simulated South Island, New Zealand winter temperature and light levels. Total herbage N uptake and DM yield were on average 24 and 48% greater in L. multiflorum than F. arundinacea respectively. Root length density (cm cm^?3 soil) in the 5‐ to 25‐cm‐depth horizon was similar between species. In the 25‐ to 45‐cm‐depth horizon, F. arundinacea roots were found at higher densities than L. multiflorum. In the 45‐ to 65‐cm‐depth horizon, root length density was fourfold to ninefold higher for F. arundinacea than L. multiflorum, but N uptake efficiency was greater in L. multiflorum (0·48 mg ¹⁵N m^?1 root) than F. arundinacea (0·09 mg ¹⁵N m^?1 root). The results suggest that deep F. arundinacea roots are relatively inactive during the winter period and confirm that plant growth is more important than root architecture (e.g. deep roots) to recover soil N and ultimately reduce nitrate leaching losses.     

‘MaxClover’ grazing experiment: I. Annual yields,botanical composition and growth rates of six dryland pastures over nine years

Six dryland pastures were established at Lincoln University, Canterbury, New Zealand, in February 2002. Production and persistence of cocksfoot pastures established with subterranean, balansa, white or Caucasian clovers, and a perennial ryegrass‐white clover control and a lucerne monoculture were monitored for nine years. Total annual dry‐matter (10.0–18·5 t DM ha^?1) and sown legume yields from the lucerne monoculture exceeded those from the grass‐based pastures in all but one year. The lowest lucerne yield (10 t ha^?1 yr^?1) occurred in Year 4, when spring snow caused ungrazed lucerne to lodge and senesce. Cocksfoot with subterranean clover was the most productive grass‐based pasture. Yields were 8·7–13·0 t DM ha^?1 annually. Subterranean clover yields were 2·4–3·7 t ha^?1 in six of the nine years which represented 26–32% of total annual production. In all cocksfoot‐based pastures, the contribution of sown pasture components decreased at a rate equivalent to 3·3 ± 0·05% per year (R² = 0·83) and sown components accounted for 65% of total yield in Year 9. In contrast, sown components represented only 13% of total yield in the ryegrass‐white clover pastures in Year 9, and their contribution declined at 10·1 ± 0·9% per year (R² = 0·94). By Year 9, 79% of the 6.6 t ha^?1 produced from the ryegrass‐white clover pasture was from unsown species and 7% was dead material. For maximum production and persistence, dryland farmers on 450–780 mm yr^?1 rainfall should grow lucerne or cocksfoot‐subterranean clover pastures in preference to ryegrass and white clover. Inclusion of white clover as a secondary legume component to sub clover would offer opportunities to respond to unpredictable summer rainfall after sub clover has set seed.     

In vitro reproduction in the annual pasture legumes subterranean clover (Trifolium subterraneum L.) and French serradella (Ornithopus sativus Brot.)

Pasture legumes are important components of both mixed farming rotations and permanent pastures in temperate climates. Breeding of two widely sown pasture legumes, subterranean clover (Trifolium subterraneum L.) and French serradella (Ornithopus sativus Brot.), is constrained by the long generation cycle, typically enabling only one generation per year. We hypothesized manipulation of culture medium and conditions would enable the development of a laboratory‐based protocol for in vitro reproduction in subterranean clover and French serradella. In vitro flowering and viable seed set was induced from both species. For subterranean clover, the most effective treatment was culturing on modified MS medium with 1 μm kinetin and 0·1 m sucrose under a 100 μmol m^?2 s^?1 light intensity and continuous photoperiod. For French serradella, culture on a hormone‐free B5 medium with 5 mm NH₄Cl and 0·1 m sucrose under a 100 μmol m^?2 s^?1 light intensity and 20 h photoperiod was optimum. It is expected this technique will have application in accelerating generation turnover within breeding programs, for the study of factors influencing flowering in pasture legumes, and for the propagation of valuable yet enfeebled plants such as embryo‐rescued hybrids.     

Root growth response of serradella species to aluminium in solution culture and soil

Serradella (Ornithopus) species are high‐quality pasture legumes that originate from the Mediterranean basin and have been increasingly used in southern Australian temperate grazing systems. They are generally regarded as tolerant of soils with low pH and, by inference, elemental toxicities such as aluminium (Al). No studies have examined the effect of high Al concentrations on the growth of French serradella (Ornithopus sativus Brot.) or newly developed cultivars of yellow serradella (O. compressus L.). Several cultivars/accessions of each species were grown in low ionic‐strength nutrient solutions at pH_Ca 4.5 containing a range of Al concentrations. Their susceptibility to root growth inhibition by Al was benchmarked against reference species ranging from Al‐sensitive to Al‐tolerant. Most serradella cultivars had moderate‐to‐high Al tolerance in solution culture but one yellow and two French serradella cultivars ranked alongside the Al‐sensitive reference species. A subset of cultivars and reference species were then grown in an Al‐toxic soil to test the validity of the solution culture results; these cultivars spanned the apparent range in Al sensitivity/tolerance indicated by the solution culture experiment. Variation in the relative root length achieved in Al‐toxic solution culture explained ~59% of the variation in the relative root length achieved in the acidic Al‐toxic soil. This result supports the conclusion that Al tolerance varies among serradella and that some cultivars may not thrive in soils with pH_Ca < 4.5 and elevated extractable Al concentrations.     

Competition of Leymus chinensis and Bromus inermis in response to gap size and neighbouring root exclusion

A two‐year small‐plot field experiment was carried out to investigate the competitive relationship between seedlings of two important forage grasses, Leymus chinensis and Bromus inermis, under three levels of gap size (distance between seedlings and their neighbours) of 10, 20 and 40 cm in diameter, with neighbouring roots present or absent. Seeds of the two species were sown into artificially created gaps, in either monoculture or mixtures at equal rates. Results indicated that gap size had significant effects on seedling emergence, seedling survival and the growth performance of the two species, grown alone or in a mixture. Excluding the roots of neighbouring plants enhanced all the measured attributes and had significant effects on both the number of inflorescences and the biomass of B. inermis and on the biomass of L. chinensis. The performance of the two species differed significantly, both alone and in mixtures, with B. inermis outperforming L. chinensis consistently. The number of inflorescences of B. inermis was 2·6‐fold higher than L. chinensis when grown in a mixture, and L. chinensis displayed a large and significant reduction in biomass when grown in a mixture with B. inermis (5·7 g plot^?1) as compared with a monoculture (25·9 g plot^?1). The relative yield (RY) for B. inermis exceeded 0·5, but for L. chinensis, it was below 0·5 in all treatments, and aggressivity (A) in all treatments was above 0. In addition, the relative competition intensity (RCI) of B. inermis was less than that of L. chinensis in all treatments, both separately and when averaged across treatments. We conclude that B. inermis is a superior competitor to L. chinensis in gaps, whereas the performance of L. chinensis was greatly suppressed in mixtures. This indicated that under similar conditions, B. inermis outcompetes L. chinensis during early growth stages. The results have practical implications for the restoration and revegetation of grasslands in northern China.     

Adaptability and productivity of some warm-season pasture species in a Mediterranean environment

Warm‐season grasses and legumes have the potential to provide forage throughout the Mediterranean summer when there are high temperatures and low rainfall and when cool‐season grasses become less productive. Twenty‐nine non‐native, warm‐season pasture species (twenty‐three grasses and six legumes) were assessed for their adaptability to the coastal plain of southern Italy in terms of their productivity and nutritional quality. The investigated species were compared with two reference species widely used in a Mediterranean environment: a grass (Festuca arundinacea) and a legume (Medicago sativa). The species differed in their phenological and biological characteristics, i.e. start of vegetative resumption, first flowering and cold resistance, from each other and from the control species. From the second year after establishment, warm‐season perennial grasses had high dry‐matter (DM) yields and, in many cases, a more than adequate nutritional quality. As for legumes, the control, M. sativa gave the best results in all the investigated characters. Among the grasses, seven species (Chloris gayana, Eragrostis curvula, Panicum coloratum, Paspalum dilatatum, Pennisetum clandestinum, Sorghum almum, Sorghum spp. hybrid) had DM yields greater than the control species and had their maximum growth during the hottest period of the year, when F. arundinacea, the control grass species, was dormant. Eragrostis curvula had the highest annual DM yield (21·1 t ha^?1) and P. clandestinum provided the best combination of agronomic and yield characteristics which were similar to those of M. sativa. The seven above‐mentioned species have the potential to supply hay or grazing and contribute to broadening and stabilizing the forage production calendar in Mediterranean‐type environments.     

Chemical composition and in vitro total gas and methane production of forage species from the Mid Rift Valley grasslands of Ethiopia

There is increasing interest in sustainable land use in the tropics to optimize animal production while also reducing methane (CH₄) emissions, but information on nutritive value and CH₄‐emission potential of tropical forage species is limited. Samples of 24 grasses and five other forages were collected during the main rainy season on randomly positioned quadrats in semi‐arid grassland in the Mid Rift Valley of Ethiopia. Samples were pooled by species, analysed for chemical composition and incubated with rumen fluid to determine total gas and CH₄‐emission potentials using a fully automated in vitro gas production apparatus. Organic matter digestibility (OMD) and metabolizable energy (ME) contents were calculated from chemical composition and gas production data. Large variability was observed among forages for all nutritional variables considered. The grasses Eleusine multiflora, Pennisetum stramineum, Dactyloctenium aegyptium, Eragrostis aspera, Cenchrus ciliaris and Eragrostis cilianensis showed relatively high OMD (68–72%) and ME values (9·1–10·2 MJ kg^?1 dry matter). Melinis repens, E. multiflora and the non‐legume forb Zaleya pentandra showed relatively low CH₄ to total gas ratios; these species may have potential for use in low CH₄‐emission forage diets. Acacia tortilis fruits had high content of crude protein and moderate ME values, and may be an ideal feed supplement for the grazing ruminant. Sodium content was below the recommended level for ruminants in all the forage species. Overall, the pasture stand during the main growing season was evaluated as having moderate nutritional quality.     

Salt tolerance variability among stress‐selected Panicum coloratum cv. Klein plants

This work assessed intracultivar variability for salt tolerance within Panicum coloratum cv. Klein, explored some physiological parameters potentially associated with it and evaluated the contribution of cell division and expansion to the decreased leaf length observed under salinity. Individual plants that had survived severe stress environments in an established pasture were collected and clonal families were obtained by vegetative propagation. These were evaluated in a greenhouse, in pots with an inert substrate irrigated with nutrient solution containing 0, 200 or 400 mm NaCl. Salt tolerance was assessed from growth variables expressed as a percentage of non‐salinized controls. Changes induced by salinity in carbon fixation, soluble sugars and compatible solutes were also measured. The selected plants showed 33% higher salt tolerance than plants from the same cultivar obtained from seeds, and variability for salt tolerance was detected within the group, suggesting these plants could be valuable germplasm for breeding programmes for saline areas. All selected plants accumulated low leaf blade Na concentrations (< 0·1 mm  g^?1 dry weight on average), and K concentrations tended to remain high under salinity. A kinematic analysis indicated a reduction in the number of cells in the division‐only zone was the main cause of shorter leaves under stress. Although plants showed some differences in all these traits, they were not related to salt‐tolerance variability within this group of stress‐tolerant plants.     

Evaluating seasonal variation in mineral concentration of cool‐season pasture herbage

Pasture herbage is a major source of minerals for livestock in pasture‐based production systems. Herbage mineral concentrations vary throughout the growing season, whereas mineral supplementation to livestock is often constant. The study objectives were to analyse the seasonal variation in herbage mineral concentrations in tall fescue [Schedonorus phoenix (Scop.) Holub]‐based pasture with regard to beef cattle mineral requirements and to create a statistical model to predict variation in herbage mineral concentrations across the growing season. Pasture herbage was analysed from 12 grazing systems in Virginia to determine its mineral concentration from April to October of 2008–2012. The pasture herbage, grown without fertilization, contained adequate macronutrient concentrations to meet the requirements of dry beef cows through the growing season and the requirements of lactating beef cows in April. Phosphorus supplementation appeared to be unnecessary for dry beef cows given adequate concentrations in pasture herbage. A model using month of harvest, soil moisture and relative humidity explained 75% of the variation in an aggregated mineral factor. The 90% prediction intervals indicated that N, P, K, S and Cu concentrations could be predicted within 1·35, 0·08, 0·80 and 0·07% and 3·83 mg kg^?1 respectively. Prediction of herbage mineral concentrations could help to improve livestock health, reduce costs to producers and limit nutrient losses to the environment.     

Forage peanut (Arachis spp.) genetic evaluation and selection

Forage peanut improvement for use in grass–legume mixtures is expected to have a great impact on the sustainability of Brazilian livestock production. Eighteen cloned Arachis spp. ecotypes were evaluated under clipping in a Brazilian Cerrado region and results analysed using a mixed model methodology. The objective was to estimate genetic and phenotypic parameters and to select the best ecotypes based on selection index applied on their predicted genotypic value. The traits of total dry‐matter (DM) and leaf DM yield presented moderate (0·30 <  < 0·50) to high (>0·50) broad‐sense heritability, in contrast to the low genetic variability in nutritional quality‐associated traits. Ecotypes of Arachis spp. contained average crude protein concentrations of 224 g kg^?1 DM in leaves and 138 g kg^?1 DM in stems, supporting the potential role of these species to overcome the low protein content in Cerrado pastures. The correlations between yield traits and traits associated with low nutritional value in leaves were consistently significant and positive. Genetic correlations among all the yield traits evaluated during the rainy or dry seasons were significant and positive. The ecotypes were ranked based on selection index. The next step is to validate long‐term selection of grass–Arachis in combination with pastures under competition and adjusted grazing in the Cerrado region.     

Effect of grazing management on herbage protein concentration,milk production and nitrogen excretion of dairy cows in mid‐lactation

The objective of this experiment was to use diurnal and temporal changes in herbage composition to create two pasture diets with contrasting ratios of water‐soluble carbohydrate (WSC) and crude protein (CP) and compare milk production and nitrogen‐use efficiency (NUE) of dairy cows. A grazing experiment using thirty‐six mid‐lactation Friesian x Jersey cows was conducted in late spring in Canterbury, New Zealand. Cows were offered mixed perennial ryegrass and white clover pastures either in the morning after a short 19‐day regrowth interval (SR AM) or in the afternoon after a long 35‐day regrowth interval (LR PM). Pasture treatments resulted in lower pasture mass and greater herbage CP concentration (187 vs. 171 g kg^?1 DM) in the SR AM compared with the LR PM but did not affect WSC (169 g kg^?1 DM) or the ratio of WSC/CP (1·0 g g^?1). Cows had similar apparent DM (17·5 kg DM cow^?1 d^?1) and N (501 g N cow^?1 d^?1) intake for both treatments. Compared with SR AM cows, LR PM cows had lower milk (18·5 vs. 21·2 kg cow^?1 d^?1), milk protein (0·69 vs. 0·81 kg cow^?1 d^?1) and milk solids (1·72 and 1·89 kg cow^?1 d^?1) yield. Urinary N concentration was increased in SR AM, but estimated N excretion and NUE for milk were similar for both treatments. Further studies are required to determine the effect of feeding times on diurnal variation in urine volume and N concentration under grazing to predict urination events with highest leaching risk.     

Soil water dynamics and dry‐matter production of old man saltbush‐, native grass‐ and lucerne‐based pastures in a variable summer‐dominant rainfall environment,Australia

In a summer‐dominant high‐rainfall, yet seasonally dry environment, soil water dynamics and dry‐matter (DM) production were monitored during 2006–12, for three perennial pasture types: old man saltbush (Atriplex nummularia ssp. nummularia with native grass), native grass (Bothriochloa macra and Rytidosperma bipartita dominant) and lucerne (Medicago sativa cv. Venus). Plant root depth of the old man saltbush pasture (1·5 m) was greater than that of native grass (1·2 m), but equal to that of lucerne (1·5 m), resulting in equivalent levels of maximum extractable water (MEW; mm, 0–1·7 m) for saltbush and lucerne in five of the six seasons. Lucerne (MEW 242 mm) extracted more soil water than native grass (144 mm), but was similar to old man saltbush (205 mm). In the second year of growth, both the lucerne and old man saltbush pastures achieved their maximum yields of 16·8 and 7·9 t DM ha^?1 respectively, but thereafter declined. The decline in yield of lucerne in later years was associated with a significantly lower plant frequency and increase in proportion of weeds. The decline in yield of old man saltbush appeared to be associated with an increasingly dry soil profile, despite receiving rainfall that was above average. The yield of the native grass pasture increased during the study as the proportion of weeds declined, and the presence of saltbush plants did not compromise the yield of perennial grasses in the inter‐row spaces. The implications of these findings for livestock production systems in this environment are discussed.     

Effects of replacing timothy silage by alsike clover silage on performance,carcass traits and meat quality of finishing Aberdeen Angus and Nordic Red bulls

The objective of the study was to determine the effects of silage plant species and cattle breed on performance and meat quality of finishing bulls. A feeding experiment was conducted using thirty Aberdeen Angus (AA) and thirty Nordic Red (NR) bulls. Both breeds were randomly allotted to three experimental diets. The composition (g kg^?1 dry matter) of the diets was as follows: (i) timothy silage (TS) (650) and barley (350); (ii) TS (325), alsike clover silage (AS) (325) and barley (350); and (iii) AS (650) and barley (350). The bulls were fed a total mixed ration ad libitum. Replacing TS by AS did not affect dry‐matter intake, growth, carcass conformation or meat quality traits of the bulls, but carcass fat score tended to decrease when replacing TS by AS (P = 0·07). The AA bulls grew faster and had better feed conversion and superior carcass conformation compared with the NR bulls (P < 0·001). The loin of the AA bulls had lower shear force value and was given higher scores in sensory analyses compared with the NR bulls (P < 0·01). The experiment demonstrated that replacing TS by AS in the diet of finishing bulls had minor effects on performance or meat quality.     

Forage biomass,soil cover,stability and competition in perennial grass–legume pastures with different Paspalum species

The short life span, irregular forage production and susceptibility to weed colonization of cool‐season grass–legume pastures are serious problems in grazing dairy systems in warm‐temperate regions. The inclusion of warm‐season species has the potential to mitigate these problems. In this study, we evaluated the effect of the inclusion of two warm‐season grasses with different growth habits on seasonal forage biomass, soil cover and weed colonization. Three different pasture mixtures were evaluated under grazing: conventional pasture (CP) [tall fescue (Festuca arundinacea), white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus)], CP with Paspalum dilatatum and CP with Paspalum notatum (CP + Pn). Forage biomass and soil cover were sampled thirteen times during a 3‐year trial, and sampling times were grouped by season for the analyses. The mixtures with Paspalum showed higher soil cover in the autumn, while in the winter CP had higher soil cover than CP + Pn. Competition with tall fescue was similar between mixtures with Paspalum, when considering biomass, but it was higher in CP + Pn when considering soil cover. The inclusion of P. notatum increased biomass during the autumn but decreased the mixture performance during winter by reducing tall fescue soil cover. The addition of a warm‐season grass species with a moderate competing ability like P. dilatatum is likely to avoid a negative impact on the cool‐season component of the pasture.     

In vitro rumen methane output of grasses and grass silages differing in fermentation characteristics using the gas‐production technique (GPT)

The chemical composition of silage consumed by cattle can influence the subsequent rumen microbial fermentation patterns and methane (CH₄) emissions. The objectives of this study were to (i) evaluate the effect of ensilage on the in vitro rumen methane output of perennial ryegrass and (ii) relate the silage fermentation characteristics of grass silages with in vitro rumen methanogenesis. Three pre‐harvest herbage‐conditioning treatments and seven silage‐additive treatments were used in a laboratory‐scale silo experiment to produce a diversity of silage fermentation characteristics. Ensilage reduced (P < 0·01) the in vitro rumen CH₄ output (mL CH₄ g^?1 dry matter (DM) disappeared). This reflected differences in the direction of rumen fermentation (lower acetic (P < 0·05) and higher propionic (P < 0·001) acid proportions in volatile fatty acids) rather than major changes in the extent of in vitro rumen fermentation (i.e. mmol VFA g^?1 DM). The magnitude of the decrease in CH₄ output (mL g^?1 DM incubated) owing to ensilage increased as the extent of silage fermentation, and in particular the lactic acid concentration, increased. In contrast, among silages with relatively similar extents of silage fermentation (i.e. total fermentation products), an increase in the proportion of lactic acid in silage fermentation products led to a more extensive in vitro rumen fermentation and thus to a greater CH₄ output (mL g^?1 DM).     

Grazing behaviour,intake and performance of dairy ewes with restricted access time to berseem clover (Trifolium alexandrinum L.) pasture

The effects of restricted access time to pasture (2, 4 or 6 h d^?1; 2H, 4H or 6H) on ingestive behaviour and performance were assessed on four occasions per target grazing day (D1, initial day; D4, intermediate day; and D7, final day) in dairy ewes rotationally grazing berseem clover with a 7‐day grazing period and a 21‐day recovery period. A randomized block design with two replicates per treatment was used. All ewes were supplemented daily with 700 g per head of concentrates and 700 g per head of ryegrass‐based hay. Pasture subplot and animal group data were analysed by a factorial model including access time (AT), grazing day (D) and their interaction as fixed factors. Sward height decreased from D1 (P < 0·001) and green leaf mass from D4 (P < 0·001) onwards during the grazing period. Grazing time as a proportion of AT was higher in 2H than in 4H and 6H ewes on D1 and D4 but not on D7 (P < 0·05 for AT × D). Herbage intake rate was higher in 2H than in 4H and 6H ewes (P < 0·001). Herbage and total intakes were higher in 4H and 6H than in 2H ewes (P < 0·001), with herbage intake varying non‐linearly during the grazing period (P < 0·05). Milk yield was higher in 4H and 6H than in 2H ewes (P < 0·01). To conclude, despite the evidence of compensatory behaviour, restricting access time to 2 h d^?1 constrained intake and performance of dairy ewes rotationally grazing berseem clover.     

Plant growth and survival of five introduced and two native/naturalized perennial grass genotypes exposed to two defoliation managements in arid Argentina

The field performance of the native Pappophorum vaginatum, the naturalized Eragrostis curvula and various cultivars of the introduced Achnatherum hymenoides and Leymus cinereus was evaluated as potential forage resources in rangelands of arid Argentina during the warm seasons of 2007/2008 and 2008/2009. Plants of these grass species, obtained from seeds, were transplanted to the field in 2006, when they were 1 year old. During the study years, there were two defoliation managements: plants of all study genotypes either remained undefoliated (controls) or were defoliated twice a year during spring at 5 cm stubble height. Despite tiller number being lower (P < 0·05) on defoliated than on undefoliated plants, and total leaf length per unit basal area being similar (P > 0·05) between defoliation managements by mid‐spring, there were no differences (P > 0·05) in dry weight production between defoliated and undefoliated plants in all genotypes at the end of the second growing season. Plants of one or more of the introduced genotypes showed a similar (P > 0·05) or greater (P < 0·05), but not lower, tiller number per plant and per square centimetre, daughter tiller production, total leaf length and dry weight production per unit basal area than the native species at the end of the first and/or second growing seasons. These morphological variables were similar (P > 0·05) or greater (P < 0·05) in the native than in the naturalized genotype. Plant survival, however, was lower (P < 0·05, overall mean = 20%) in the introduced than in the native (>70%) or naturalized (>39%) genotypes at the end of the first or second growing seasons.     

Methylotrophic yeast,lactic acid bacteria and glycerine as additives for sugarcane silage

The ensiling of sugarcane results in high dry‐matter (DM) loss, but the addition of glycerine may compensate for the loss during ensiling. Methanol is the most undesirable contaminant of crude glycerine destined for animal feeding. The aim of this study was to evaluate the ability of the yeast strain Pichia methanolica NCYC 1381 to reduce the methanol concentration in sugarcane silage inoculated with Lactobacillus hilgardii CCMA 0170 + glycerine. A randomized design consisted of four dose rates of glycerine (0, 4, 8 and 12% of fresh forage), three periods of silage fermentation (11, 34 and 68 d) and three combinations of microbial additives [L. hilgardii (LH), L. hilgardii plus P. methanolica (LH + PM) and without microbial additive (WI)]. The DM of the fresh sugarcane was 275 g kg^?1. The linear reduction in neutral detergent fibre caused by glycerine inclusion was probably due to a dilution effect. The LH treatment increased the concentrations of the succinic, acetic and propionic acids, and 1,2‐propanediol, and reduced the yeast population. The LH + PM treatment increased DM loss of sugarcane silage with 12% glycerine and L. hilgardii CCMA 0170 (6·1 log cfu g^?1 of FM) reduced the DM loss when compared to the silage without additives. Under the conditions of the experiment, the P. methanolica treatment did not reduce the methanol concentration in silage.     

Micronutrient concentrations in common and novel forage species and varieties grown on two contrasting soils

We investigated differences between forage species with regard to micronutrients that are essential to sustain livestock health. Five grasses (timothy, perennial ryegrass, meadow fescue, tall fescue and cocksfoot), three legumes (red clover, white clover and birdsfoot trefoil) and four forbs (ribwort plantain, salad burnet, caraway and chicory) were grown on one micronutrient‐poor/low pH soil and one micronutrient‐rich/high pH soil (outdoor pot experiment). In addition, six grasses (timothy, perennial ryegrass, meadow fescue, tall fescue, Festulolium hybrid and cocksfoot) and one legume (red clover) were field‐grown on the micronutrient‐poor soil. Of the twelve pot‐grown species, herbage of chicory, red clover and white clover generally had the highest micronutrient concentrations (maximum Co, Cu, Fe and Zn concentrations were 0·23, 9·8, 233 and 109 mg kg^?1 DM, respectively), except for Mo, which was highest in the clovers (10·6 mg kg^?1 DM), and Mn, which was highest in cocksfoot (375 mg kg^?1 DM). Soil type had the strongest effect on plant Mo and Mn concentrations. We also investigated differences in micronutrients between varieties, but they were generally few and negligible. The results indicate that choice of forage species is of major importance for micronutrient concentrations in herbage and that soil type exerts a major effect through pH. Forage of chicory, red clover and white clover generally met the requirements of high‐yielding dairy cows with regard to most micronutrients; therefore, diversification of seed mixtures so as to include these species could increase micronutrient concentrations in forage.