Diet selection of dry and lactating beef cows grazing extensive pastures in late autumn

The diet selection, made by twelve dry and twelve lactating spring‐calving Salers beef cows at the end of the grazing season on an extensively grazed natural mountain pasture in central France, was compared. Sward structure, selection bites, daily grazing time and digestibility of the diet were measured in mid‐October (P₁) and mid‐November (P₂). Live weights were measured twice monthly throughout the experiment. Daily milk production was assessed in the week before the grazing behaviour measurements. Lactating cows grazed more selectively than dry cows: they took more bites on green patches (0·20 vs. 0·13 of total bites, P < 0·01; Jacob's selectivity index: 0·13 vs. ?0·25, P < 0·001), which is consistent with the higher overall nitrogen concentration in faeces (18·1 vs. 17·3 g kg^?1 DM, P < 0·05). Lactating cows tended to slightly increase their daily grazing time compared with dry cows (on average 9·9 vs. 9·5 h, P = 0·07) and grazed faster in mid‐November (74 vs. 69 bites min^?1, P < 0·05). The lactating cows lost more live weight (?24 vs. ?12 kg cow^?1, P < 0·05) between P₁ and P₂. A positive correlation was found between consumption of green patches by lactating cows and their daily milk production in P₂ (r = 0·574, P = 0·05), whereas no correlation occurred between individual milk production and liveweight loss. Dry cows were less selective, which supports management practices that promote the use of cows with low requirements on extensively grazed pastures in late season.     

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.     

Characterization for industrial purposes of the fibre anatomy of perennial ryegrass and tall fescue stem and leaf at three stages in the primary growth

Characterization of grass fibre is important in assessing its potential for industrial fibre applications. Stem and leaf sections were sampled from triplicate field plots of two grass species, perennial ryegrass (PRG) and tall fescue at three dates (monthly from 12 May) in the primary growth, and were used to (a) isolate individual fibre cells and (b) prepare transverse sections. Microscopy and image analysis software were used to determine the length and width of individual fibre cells and the proportion of lignified fibre in stem and leaf transverse sections. The length and width of individual fibre cells were greater (P < 0·001) in stem than in leaf sections, while individual fibre cell length was greater (P < 0·01) for tall fescue than PRG. Harvest date and grass species had little effect (P > 0·05) on the proportion of lignified fibre in the transverse‐sectional area. However, there was a greater (P < 0·001) proportion of lignified fibre in the transverse‐sectional area of grass stems than leaves, with tall fescue having a greater (P < 0·05) stem and leaf transverse‐sectional area and area of lignified fibre in transverse section than PRG. Tall fescue harvested at a later stage of growth, with higher proportions of stem than leaf tissue, may be more suitable for industrial fibre applications.     

The use of pasture reflectance characteristics and arbuscular mycorrhizal root colonization to predict pasture characteristics of tallgrass prairie grazed by cattle and bison

An experiment was conducted to evaluate the potential for using arbuscular mycorrhizal fungal (AMF) root colonization and pasture reflectance characteristics as indicators of changes in tallgrass prairie vegetation resulting from differences in grazing history. The experiment was conducted within the context of a separate long‐term experiment in which eight 4·9‐ha pastures were grazed by either bison or cattle for nine consecutive years. Two separate ungrazed pastures were selected for comparison with grazed areas on the basis of similarity in burning regime, vegetation, soil and topographic characteristics. Four 45 m‐long transects were located in the upland sites within each pasture, and four plots were clipped to ground level along each transect. Reflectance readings were taken with a hand‐held radiometer at each sampling location and a soil core was collected within each plot for analysis of AMF root colonization. Reflectance readings at sixteen different wavelengths were used directly as inputs during multiple regression development or were transformed into each of three vegetation indices (normalized difference vegetation index, soil‐adjusted vegetation index and wide‐dynamic‐range vegetation index) and used in simple linear regressions. Ungrazed pastures were characterized by higher (P < 0·01) grass biomass, total biomass and canopy height than grazed pastures, but had a lower proportional abundance of forbs (P < 0·01) and amounts of forb biomass (P = 0·04). Species of herbivore did not significantly influence above‐ground characteristics that were measured. In general, AMF root colonization was relatively small and was not significantly affected by treatment and, accordingly, the variation was insufficient to test its potential as an indicator of grazing effects on vegetation or its potential relationship with pasture reflectance. Multiple regression equations based on individual wavelength reflectance values explained significantly more of the variation in above‐ground vegetation characteristics than did simple regressions using vegetation indices as predictor variables (r² values from 0·36 to 0·46 vs. 0·11 to 0·27) and have the potential to predict above‐ground vegetation characteristics in heterogeneous rangelands.     

Herbage production,nutritive value and animal productivity within hardwood silvopasture,open and mixed pasture systems in Appalachia,United States

Demand for livestock food products is projected to increase dramatically through to 2050. Increased livestock production capacity on marginal lands will be critical to meeting this demand. A 5‐year research effort was undertaken to evaluate lamb and sward productivity within open and hardwood silvopasture (SP) systems in Appalachia, USA. Grazing began in mid to late April each year, with the grazing season averaging 141 d. Grazing system treatments during 2002 and 2003 grazing seasons were as follows: 100% open pasture (OP), 67% OP and 33% SP, and 67% OP and 33% SP with delayed SP grazing initiation (OSD). In 2004, a 100% SP (SP) system was added. Animals were rotationally stocked through either 6 (2002–2004) or 7 (2005–2006) paddocks. Open pasture produced greater (P < 0·001) grazing season herbage yield, while all systems generated similar animal performance. Based on summer solstice, herbage production in spring was greater (P < 0·001) than summer, except in 2003. Total non‐structural carbohydrate (TNC) content was greater (P < 0·05) in spring than in summer, except in 2004. Animal performance was superior in spring versus summer (P < 0·001). Animal plasma urea nitrogen (PUN) was lower (P < 0·05) for OP in 2003. When PUN was correlated with nutritive value indicators, the ratio of TNC to crude protein (CP) had the strongest correlation. The strong correlation indicates the need for synchronized ruminal energy and CP availability. Development of silvopasture from existing woodlots has potential to improve whole farm productivity on marginal lands.     

Pasture use and management strategies in the Ankole pastoral system in Uganda

The Bahima ethnic group have been crossbreeding autochthonous Ankole with Holstein‐Friesian cattle. Separate herds (pure Ankole and crossbreds) are common. A survey was conducted to characterize pasture utilization and management in the Ankole region to gain a better understanding of current and emerging practices. Herds are largely grazed by continuous stocking although there are efforts to establish paddocks. Factors considered for pasture allocation to cattle genotypes were high‐quality feed, limited shrubs/weeds and close proximity to homestead for 80, 80 and 30% of farmers, respectively. Cross‐bred cattle were kept on medium/high‐quality, and Ankole cattle on medium/low‐quality pastures. Pastures for cross‐bred cattle yielded 0·17 t ha^?1 more dry matter than pastures allocated to Ankole cattle. Crude protein (CP) content of Ankole pasture was significantly (P < 0·05) lower than CP of cross‐bred pasture (6·3% compared with 7·3%). Neutral detergent fibre content was similar (72·8% vs. 69·8%) for both pasture types. Farmers’ perceptions of indicator plant species were important for allocation of pasture. Hyparrhenia rufa, Brachiaria spp., Themeda triandra and Chloris gayana were identified as the preferred pasture species. Sporobolus pyramidalis and Cymbopogon afronardus were the most undesirable pasture species. Brachiaria spp. offers an opportunity for utilization as hay for dry season supplementation.     

Grazing preference of Merino sheep for naturalized annual clover species relative to commonly sown clover species

Selective grazing of white clover (Trifolium repens) over grass species in temperate pastures results in reduced clover abundance and availability over time. Within sheep‐ and cattle‐grazed dryland (<800 mm annual rainfall) hill and high country areas of New Zealand, naturalized unsown annual clover species show greater persistence and abundance over sown clovers. With a view to understanding legume abundance in these areas, Merino sheep grazing preference was investigated for pure swards of naturalized species Trifolium dubium, T. glomeratum, T. arvense and T. striatum and commonly sown species T. repens and T. subterraneum. The Chesson–Manly preference index was used to explore the hypothesis that grazing preference differs between these species and changes as plants mature. Herbage offtake was quantified at vegetative (mid–late spring; November) and reproductive (early summer; December) stages of plant maturity. Significant preference distinctions between species (P < 0·05) occurred in December, with relative preference ranging from 0·248 for T. repens to 0·065 for T. dubium. Reduced relative preference for naturalized species was related to decreasing nutritive value from spring to summer, reflecting increased stem and flower sward content. Relative preference was negatively related to increasing acid detergent fibre and neutral detergent fibre and positively related to greater crude protein and dry‐matter digestibility. Naturalized annual clover species of lower grazing preference at reproductive maturity will benefit pasture sustainability via herbage and seed production and associated nitrogen‐fixation inputs.     

Quantifying the influence of sward height, concentrate level and initial milk yield on the milk production and grazing behaviour of continuously stocked dairy cows

Two factorial design experiments were carried out in the spring of 1994 and 1995, each of 6 weeks, to quantify the effects of sward height (SH), concentrate level (CL) and initial milk yield (IMY) on milk production and grazing behaviour of continuously stocked dairy cows. In Experiment 1, forty‐five Holstein Friesian cows were in five groups with initial milk yields of 16·9, 21·1, 28·0, 31·5 and 35·5 kg d^–1, grazed sward heights were 3–5, 5–7 and 7–9 cm (LSH, MSH and HSH respectively), and concentrates were fed at rates of 0, 3 and 6 kg d^–1. In Experiment 2, 48 cows were in two groups with IMY of 21·3 and 35·5 kg d^–1, grazed sward heights were 3–5 and 7–9 cm (LSH and HSH), and concentrates were fed at 0 and 6 kg d^–1 and ad libitum. Multiple regression models were used to quantify the effects of the three variables on milk yield persistency (MYP), estimated herbage dry‐matter (DM) intake (HDMI), grazing time (GT) and rate of DM intake (RI). The partial regression coefficients showed that increased SH led to increased MYP (Experiment 1 P < 0·001, Experiment 2 P < 0·05), increased HDMI (P < 0·01, P < 0·01), increased GT (P < 0·001, P < 0·05) and increased RI (P < 0·001, P < 0·05). Increasing CL led to increased MYP (NS, P < 0·001), decreased HDMI (P < 0·001, P < 0·001), decreased GT (NS, P < 0·001) and decreased RI (P < 0·001, P < 0·001). Higher IMY level of cows decreased MYP (P < 0·001, P < 0·001), increased HDMI (P < 0·001, P < 0·001), increased GT (P < 0·001, P < 0·05) and increased RI (P < 0·05, P < 0·01). The models were highly significant (P < 0·001), and accounted for 0·48–0·87 of the total variance. The partial regression coefficients quantified the extent to which GT and RI by cows respond positively to higher IMY, and negatively to increased CL, but respond differently (GT declines in response to a higher RI) with increasing SH.     

Nitrogen recovery and loss in a fertilized elephant grass pasture

Limited information is available regarding the recovery and loss of fertilizer nitrogen (N) applied to intensively managed tropical grass pastures. An experiment was carried out in Brazil to determine the fertilizer‐N recovery and ammonia volatilization loss in an elephant grass (Pennisetum purpureum, Schum.) pasture fertilized with 100 kg N ha^?1 as urea or ammonium sulphate, labelled with ¹⁵N, in late summer (LS) or in mid‐autumn (MA). Herbage mass was highest and litter mass was lowest in LS (P < 0·05). The N concentration of herbage was highest in autumn (P < 0·05) and the total N content in soil was lower in LS than in MA (P < 0·05), reflecting the high N uptake capacity of the grass. Proportionately higher ¹⁵N recovery in litter mass (P < 0·05) was observed in autumn (0·094) than in LS (0·0397) and the ¹⁵N recovery in herbage was 0·046 higher for ammonium sulphate‐fertilized pastures (P < 0·05; proportionately 0·243 for ammonium sulphate and 0·197 for urea). Around 0·60 of the fertilizer‐¹⁵N recovered was retained in soil and in non‐harvestable fractions of the plant. The NH₃ volatilization loss was higher in LS and most of the N loss occurred soon after fertilizer application. Urea and ammonium sulphate fertilizers were equally effective in sustaining herbage dry matter yield in the short term. However, the use of ammonium sulphate, rather than urea, would be preferable for LS applications when the objective is to reduce NH₃ volatilization losses.     

The effects of incorporating small quantities of straw in grass/grass silage-based diets for dairy cows

Two studies were conducted to examine the effects of incorporating small quantities of straw in the diets of dairy cows. In Experiment 1, forty Holstein Friesian dairy cows were used in a 2 × 4 factorial design experiment, with factors examined consisting of two parities (primiparous and multiparous animals) and four levels of straw inclusion in the diet (0, 0·08, 0·16 and 0·24 of forage dry matter). The basal forage offered in this study was grass silage, and the primiparous and multiparous animals were supplemented with 9·0 and 11·0 kg concentrate d^–1 respectively. In Experiment 2, forty‐eight Holstein Friesian dairy cows were used in a 2 × 3 factorial design experiment, with factors examined consisting of two basal forage types (grass silage and zero‐grazed grass) and three levels of straw inclusion (0, 1·0 and 2·0 kg d^–1). All animals were offered 7·0 kg d^–1 of a concentrate supplement. Both experiments were partially balanced changeover designs, consisting of two, 4‐week periods. In Experiment 1, the total dry‐matter intake followed a significant quadratic relationship (P < 0·05), increasing with low levels of straw inclusion and decreasing at higher levels of inclusion. With increasing levels of straw inclusion, there was a linear decline in milk yield (P < 0·001) and milk protein concentration (P < 0·05), but milk fat concentration was unaffected (P > 0·05). In Experiment 2, the effect of straw inclusion on total dry‐matter intake was quadratic (P < 0·001), with intakes being maximum at the 1·0‐kg level of straw inclusion. Milk yield exhibited a linear decrease (P < 0·001) with increasing level of straw inclusion. Milk fat concentration was lowest at the 1·0 kg rate of straw inclusion (P < 0·05), but milk protein concentration was unaffected by straw inclusion. There were no significant interactions between basal forage type and level of straw inclusion for any of the variables examined (P > 0·05). Despite small increases in total dry‐matter intake at a low level of straw inclusion, there was no evidence that straw inclusion improved either nutrient utilization or animal performance. The reduction in milk yield observed with straw inclusion reflects, to a large extent, a reduction in metabolizable energy intake.     

Increased concentration of water-soluble carbohydrate in perennial ryegrass (Lolium perenne L.). Evaluation in dairy cows in early lactation

Twelve multiparous Holstein–Friesian dairy cows in early lactation were used to investigate the potential of using perennial ryegrass (Lolium perenne) with a high concentration of water‐soluble carbohydrates (WSC) to increase the efficiency of milk production. Ad libitum access to one of two varieties of zero‐grazed herbage was given continuously for 3 weeks: treatment High Sugar (HS), an experimental perennial ryegrass variety (Ba11353) bred to contain a high concentration of WSC, harvested in the afternoon; or Control, a standard variety of perennial ryegrass (cv. AberElan), harvested in the morning. All dairy cows also received 4 kg d^?1 of a standard dairy concentrate. Dairy cows given the HS diet treatment consumed 2·8 kg dry matter (DM) d^?1 more than Control dairy cows (P < 0·01), and the DM digestibility of the diet on the HS treatment was significantly greater than that of the diet on the Control treatment (0·75 vs. 0·72; s.e.d. 0·010; P < 0·05). Excretion of urinary purine derivatives (PD) tended (P < 0·1) to be higher from dairy cows on the HS treatment, implying increased microbial protein flow to the duodenum, although there was no significant difference in the apparent efficiency of rumen fermentation of either dietary nitrogen (N) or DM expressed as a ratio to urinary PD. Milk yields and milk composition were not significantly affected by dietary treatment, although true protein yields of milk were higher (P < 0·05) from dairy cows given the HS treatment. The proportion of dietary N excreted in urine was significantly lower from HS cows, although the values were low for both treatments (0·20 g g^?1 vs. 0·27 g g^?1; s.e.d. 0·020; P < 0·05). It is concluded that increased DM intakes by dairy cows given the HS treatment led to increased milk protein outputs. With a proportional decrease in urinary N excretion, the use of perennial ryegrass with a high WSC concentration, in the context of the harvesting regime used in this study, may help to reduce N pollution from dairy systems into which it is incorporated.     

Weight gains,blood parameters and faecal egg counts when meat‐goat kids were finished on alfalfa,red clover and orchardgrass pastures

The experiment was conducted in 2005–2007 to evaluate weight performance, blood parameters associated with forage nutrient‐use and anaemia from gastrointestinal nematode (GIN) infection, and faecal egg count (FEC) patterns of meat‐goat kids finished on alfalfa (Medicago sativa L.; ALF); red clover/grass mixture (Trifolium pratense L.; RCG); and orchardgrass (Dactylis glomerata L; OGR) pastures. Forage mass, crude protein (CP) and total digestible nutrients (TDN) displayed complex interactions between treatment and time (P < 0·001) across the grazing seasons. Final body weight was greater for goats finished on ALF and RCG than on OGR, except in 2006 when ALF was greater than RCG or OGR. The TDN/CP ratios in forages and blood urea nitrogen concentrations in grazing goats were highly correlated (r = 0·99; P = 0·02) and suggested that animals were wasting forage protein. Faecal egg count was variable over the grazing season each year (date and treatment × date interaction; P < 0·001), but in general, FEC indicated that goat kids grazing ALF were less affected by GIN than kids grazing RCG or OGR. Research is needed to determine whether strategic energy supplementation would improve protein‐use efficiency and resilience to parasite infection when finishing meat goats on pastures managed for high forage nutritive value.     

The effect of forage type and level of concentrate supplementation on the performance of spring-calving dairy cows in early lactation

Abstract In 1993 and 1994, 40 cows in early lactation in early spring were assigned randomly to four feeding treatments. One group of cows was kept indoors with access to grass silage ad libitum, plus 6 kg of concentrate daily. The other three groups had access to grass pasture (5–6 h per day in 1993 and 11–12 h per day in 1994) plus grass silage similar to that fed to the previous group while indoors plus 6, 4 or 2 kg of concentrate daily. The average daily allocations of herbage (> 3·5 cm) were 8·5 and 14·0 kg DM cow^?1 day^?1 in 1993 and 1994 respectively. The treatments were applied for 8 weeks (26 February to 23 April) in 1993, and 7 weeks (11 March to 29 April) in 1994. Cows with access to pasture had lower (P < 0·001) silage dry‐matter (DM) intakes and higher (P < 0·001) total forage DM intakes in both years than those kept indoors. This resulted in significantly higher yields of milk, fat, protein and lactose. Similarly, milk protein concentration was higher (P < 0·05 in 1993; P < 0·001 in 1994). There was a significant linear increase in total DM intake in both years with increased concentrate supplementation. In 1993, there was a linear increase in milk (P < 0·01), fat (P < 0·01), protein (P < 0·001) and lactose (P < 0·01) yields with increased concentrate supplementation. In 1994, only milk protein yield (P < 0·05) was increased. Concentrate supplementation had no effect on milk composition or liveweight change. Cows with access to grazed grass had higher liveweight gains (P < 0·05) than those kept indoors in both years. In 1993, increasing the energy intake increased the processing qualities of the milk produced. The results showed that access to grass pasture resulted in higher milk production, in reduced silage requirement and in reduced level of concentrate supplementation required for a given level of milk production with spring‐calving cows in early lactation compared with those kept indoors.     

Effect of early turnout to grass in spring on dairy cow performance

This experiment examined the effects of grazing severity and degree of silage restriction during early turnout of dairy cows to pasture in spring on animal performance. Forty late‐winter‐calving Holstein Friesian dairy cows were allocated to one of five treatments between 7 March and 17 April 1997. The treatments involved early turnout of cows to grass for 2 h per day at two residual sward heights and two silage allowances, plus a control treatment, in a randomized block design. Dairy cows on the control treatment remained indoors throughout the experiment and were offered grass silage ad libitum. Dairy cows on all treatments were also offered 6 kg d^–1 of a concentrate on a flat‐rate basis, split equally between the morning and afternoon milkings. Offering cows access to pasture in early spring for 2 h per day resulted in increases in both milk (P < 0·001) and protein yield (P < 0·01). On average, over all grazing treatments, cows produced an additional 2·6 kg milk per day compared with the control treatment (28·5 vs. 25·9 kg d^–1, s.e.m. 0·43). Furthermore, these increases in milk yield were obtained even when silage was restricted indoors (28·4 vs. 25·9 kg d^–1) and cows grazed down to a residual sward height of 40 mm (28·1 vs. 25·9 kg d^–1). Protein yield was higher (P < 0·01) with dairy cows grazing pasture compared with cows indoors (848 vs. 707 g d^–1, s.e.m. 28·9). Silage intake was significantly (P < 0·001) reduced when cows were turned out to pasture. In conclusion, early turnout of dairy cows to pasture in spring for 2 h per day reduced silage intake and increased milk yield and protein yield relative to those fully housed and offered grass silage with a low level of concentrates.     

Continuous and rotational grazing of dairy cows – the interactions of grazing system with level of milk yield, sward height and concentrate level

An experiment was conducted to test the hypothesis that for cows with high levels of milk yield, rotational grazing produces higher milk yields than continuous grazing. The comparison of grazing systems was made at two levels of milk yield (initially 20·3 and 32·5 kg d^?1), and interactions with sward height and concentrate level were also examined. The study used 48 multiparous Holstein Friesian cows over a period of 62 d. Mean milk yield, its persistency and composition, live weight, body condition score and liveweight gain were not significantly affected by grazing system at either level of milk yield. There were no significant interactions between grazing system and sward height or concentrate level for any milk production measurement. Mean estimated herbage and total dry matter (DM) intake (P < 0·01), grazing time (P < 0·05) and ruminating time (P < 0·01) were significantly greater on the continuous grazing system. The cows in the higher milk yield group and those grazed at the higher sward height had a significantly (P < 0·05) higher estimated daily herbage DM intake and rate of herbage intake on the continuous grazing system than those on the rotational grazing system. There was no evidence to support the hypothesis that rotational grazing systems support higher levels of milk production than continuous grazing for cows of high milk yield. The shorter grazing time on the rotational grazing system indicated that cows may anticipate the timing of the daily movement of the electric fence, and this reduces their time spent grazing residual herbage.     

Effect of swath treatment on water loss during field-wilting and on feeding value of perennial ryegrass silage

The effect of spreading mown perennial ryegrass (Lolium perenne) herbage over the total ground area on water loss during field-wilting was compared with leaving herbage in swaths (three swaths put together into one, occupying 0·18 of ground area) in three experiments. Spread crops were not tedded during wilting but were rowed up immediately before harvest. In all experiments, conventional silage-making equipment was used on a field scale. Feeding value was assessed with lactating dairy cows and growing heifers (Experiment 1) and sheep (Experiment 3). The periods of field wilting were 48 h (Experiment 1), 24 h (Experiment 2) and both 24 h and 48 h (Experiment 3). Spreading the crop was associated with larger increases in loss of water in all three experiments compared with leaving grass in swaths. Losses of dry matter (DM) during wilting were similar in Experiment 2 but were higher for the swathed crop wilted for 48 h than for 24 h in Experiment 3. Spreading resulted in restricted fermentations associated with higher crop DM contents at ensiling. In Experiment 1 the concentrations of DM, ash and water-soluble carbohydrate in silage were higher (P < 0·001) for spreading the crop and the concentrations of crude protein and neutral-detergent fibre were lower (P < 0·05) than for swathed material. In Experiment 3, spreading was associated with higher concentrations of water-soluble carbohydrates and ethanol and lower concentrations of fermentation acids, ammonia-N and neutralizing value in silage. Voluntary DM intake of silage by dairy cows and heifers was higher for spread than for swathed material (P < 0·05), but in Experiment 3 (sheep) there were no significant differences between treatments in voluntary intake of DM. The increased intake by dairy cows of silage from spread herbage was reflected in increased concentrations of milk fat (P < 0·01) and protein (P < 0·05) but not in milk yield (P > 0·05). It is concluded that spreading herbage during field wilting prior to ensiling accelerates water loss and has the potential to improve the feeding value of the ensiled product.     

Dairy cow performance and labour inputs associated with two silage feeding systems

Two experiments were conducted to examine the effect of two winter feeding systems on the performance of dairy cows in early lactation. Experiments 1 (144 d duration) and 2 (146 d duration) involved sixty‐four (primiparous) and eighty‐six (primiparous and multiparous) Holstein Friesian dairy cows respectively. Rations offered comprised grass silage, maize silage [0·26–0·29 of forage dry matter (DM)] and concentrates (10–12 kg d^?1). With the complete diet (treatment CD), the forage and concentrate components were mixed using a complete diet mixer wagon, and offered daily in the form of a ‘complete diet’. With the easy feed (treatment EF), the dairy cows were offered the forage component of the ration twice weekly in whole blocks, in quantities sufficient for the following 3‐ or 4‐d period, while the concentrate component of the diet was offered via electronic out‐of‐parlour feeding stations. Total DM intakes were similar, namely 17·6 and 17·0 kg d^?1 (Experiment 1) and 18·7 and 18·5 kg d^?1 (Experiment 2), for treatments CD and EF respectively. Feeding system had no significant effect on milk yield, milk fat or milk protein content, or on end of study indices of body tissue reserves in either experiment (P > 0·05). Similarly, feeding system had no significant effect on the digestibility of the ration measured in Experiment 2 (P > 0·05). Feeding times associated with each component of the two feeding systems were measured, and these were then used to calculate total feeding time for a 97‐cow dairy herd. Calculated feeding times for this herd were 209·3 and 156·0 min week^?1 for treatments CD and EF respectively.     

Effects of feeding fodder beet and concentrates with different protein contents on dairy cows offered silage ad libitum

In two changeover design experiments, fifteen early- and sixteen late-lactation cows were used to investigate the effects of offering food beet with ad libitum grass silage and concentrates with different CP content on milk yield and quality. In Experiment 1 (early lactation) cows were offered no fodder beet (0) or 4 kg DM d^?1 (4) in conjunction with one of three concentrates containing 159, 191 or 244g CP kg^?1 DM (L.M.H.). Treatments were therefore 1L/0, 1L/4, 1M/0, 1M/4, 1H/0 and 1H/4. In Experiment 2 (late lactation) cows were offered the same level of fodder beet in conjunction with two concentrates containing 129 and 229 (L,H) g CP kg^?1 DM. Treatments were therefore 2L/0, 2L/4, 2H/0 and 2H/4. In both experiments feeding fodder beet reduced silage DM intakes (P < 0·001) and increased total DM intake (P < 0·05 to P < 0·001). The substitution rate (r) ranged from 0·46 to 0·59kg of silage DM (kg^?1 fodder beet DM). In Experiment 1, fodder beet tended to increase milk yield, composition and yield of constituents, but the effect was statistically significant for milk protein content only (P < 0·01). In Experiment 2, milk yields for 2L/0, 2L/4, 2H/0 and 2H/4 were 11·3, 12·1, 11·7 and 12·5 kg d^?1 respectively (s.e.d. 0·43, non-significant), fat contents were 44·4, 47·3, 44·3 and 46·8g fat kg^?1 respectively (s.e.d. 0·73, P < 0·001), protein contents were 34·3, 35·6, 35·3 and 36·2 g protein kg^?1 respectively (s.e.d. 0·28, P < 0·001), fat yields were 494, 574, 512 and 579 g fat d^?1 respectively (s.e.d. 20, P < 0·001) and protein yields were 385, 426, 407 and 442 g protein d^?1 (s.e.d. 13, P < 0·01) respectively. Increasing CP in the concentrate significantly increased milk yield in Experiment 1 (23·9, 22·5, 23·5, 23·8, 26·2, 26·5kg d^?1 for 1L/0, 1L/4, 1M/0, 1M/4, 1H/0 and 1H/4 respectively, P < 0·05). Higher CP in concentrate also resulted in significantly increased milk protein yield in early-lactation (P < 0·001) and milk protein content in late-lactation (P < 0·01) cows. There was a significant interaction between fodder beet and concentrate CP content for milk protein yield (P < 0·001) in Experiment 1.     

Effects of ethanol,molasses and Lactobacillus plantarum on fermentation characteristics and aerobic stability of total mixed ration silages

This study was conducted to evaluate the effects of Lactobacillus plantarum, molasses and/or ethanol on fermentation quality and aerobic stability of total mixed ration (TMR) silage, which is widely used in dairy cow diets at mid‐to‐late lactation in Tibet. TMR was treated with ethanol (E), molasses (M), Lactobacillus plantarum(L), ethanol+molasses (EM), ethanol+Lactobacillus plantarum (EL) plus control. After 45 d of ensiling, inoculant significantly (P < 0·05) increased lactic acid (LA) concentration and decreased pH, ammonia nitrogen (AN) concentration, and aerobic bacterial and yeast counts, compared to control. After the first 3 d of aerobic exposure, LA for silages without ethanol started to decrease, while LA for E silages almost remained unchanged till the end of the aerobic exposure period. The pH in TMR silages without ethanol gradually increased, while that for E and EL remained about 4·60 and 4·00, respectively, and EL showed the lowest pH among six silages over the course of aerobic exposure. Aerobic bacterial counts in control, M and EM silages were significantly higher (P < 0·05) than those in E, L and EL, and yeast counts in E and EL silages were significantly lower (P < 0·05) than those in other silages after 9 d of aerobic exposure. The results suggest that inoculation with L. plantarum was more effective in altering fermentation characteristics than adding molasses, while ethanol showed a potential to protect TMR silages from pH increase and delayed the growth of aerobic bacteria and yeast either alone or in combination with L. plantarum.     

Production of beef cattle grazing on Brachiaria brizantha (Marandu grass)—Arachis pintoi (forage peanut cv. Belomonte) mixtures exceeded that on grass monocultures fertilized with 120 kg N/ha

Mixed grass/legume pastures are an alternative to grass monocultures for increased beef cattle production in tropical climates. The objective of this study was to evaluate the productivity of beef cattle grazing either a mixed pasture of Brachiaria brizantha cv. Marandu grass and Arachis pintoi (forage peanut) cv. Belomonte or a Marandu monoculture, under rotational stocking. Five trials were conducted over a period of nine years in north-eastern Brazil where the sward structure (forage, grass and legume mass) and animal performance were compared for a mixed Marandu grass/forage peanut pasture, and a Marandu grass monoculture with 120 kg N ha⁻¹ y⁻¹. Stocking rate was adjusted to maintain forage allowance at 4% body weight/day. A block design was used with four replicates, and warm and cool seasons within each trial were considered, using repeated measurements over time. In the warm season, the forage mass in the mixed pastures was 17% greater than in the monoculture (p = .049), and the stocking rate, average daily gain and liveweight gain per ha were 16.4%, 20.0% and 28.7% greater (p = .004, p < .001 and p < .001 respectively). The average daily gain showed a positive linear relationship with the legume proportion in the sward (p < .001). The mixed forage peanut/Marandu pasture sustained significantly greater beef cattle production (789 kg ha⁻¹ y⁻¹) compared to the N-fertilized grass monoculture (655 kg ha⁻¹ y⁻¹). Appropriately managed, mixed pastures of forage peanut/Brachiaria pastures are sustainable and have high potential for use in the humid tropics.