Matter Herbage Research Articles

How Are Warm-Season Pastures’ Nutritive Value and Fermentation Characteristics Affected by Open Pasture, Silvopasture, and Sward Herbage Maturity?

This study aimed to evaluate the forage mass and nutritional value (NV) of Guinea Massai grass (Megathyrsus maximus × Megathyrsus infestum) in an open pasture (OP) or the silvopastoral system (SPS) at different stages of development (SDs). The experimental design was completely randomized, with five replications. The treatments were distributed in a factorial scheme 2 × 4, corresponding to types of systems (OP and SPS) and four SD (vegetative stage—S1, pre-flowering—S2, full flowering—S3 and maturity after flowering—S4). There was no interaction of the system × stage of plant development in any of the variables evaluated. The production of forage mass and Guinea Massai grass morphological components did not differ (p > 0.05) between SPS and OP. However, they differed between the SDs (p ≤ 0.05), with an increasing linear effect for forage mass, percentage of the stem, and dead material, and decreasing for leaf percentage and leaf: stem ratio. Only protein content differed (p < 0.05) among the chemical composition variables between culture systems. The shading caused by the SPS did not decrease the forage mass, NV, and in vitro dry matter digestibility of Guinea Massai grass compared to the system in OP. The advance of the SD of Guinea Massai grass increases the forage mass, with higher proportions of morphological components of low NV, such as stem and dead material. Silvopastoral system of Guinea Massai grass and eucalyptus is effective to prolongate the grazing season, with a greater amount of green leaves in the sward and better NV, without compromising herbage mass production in the forage growing season.

Effects of early herbage cutting and vine leaves on methane emission, urine nitrogen losses, and the milk fatty acid profile of dairy cows.

Methane mitigation in dairy cows is an essential part of combating global warming. Governments and consumers have become increasingly interested in herbage-based feeding, and premium prices are often paid for these types of dairy products. However, this feeding strategy is presumed to produce more methane per unit of feed or milk than corn silage- or concentrate-based diets due to higher fiber intakes. Immature herbage is preferred to maintain dairy cow performance, but the high content of N and digestible fiber may increase methane and urine N emissions compared with more mature herbage. Tannin-containing feeds, such as vine leaves (Vitis vinifera), may help to combat the emissions associated with feeding immature herbage. Our study aimed to evaluate differences between early-stage (ES; 21 d of regrowth) versus late-stage (LS; 42 d) herbage and the effects of vine leaves on methane and nitrogenous emissions and the milk fatty acid profile of dairy cows. Twenty-four mid- to late-lactating dairy cows were randomized to 4 dietary groups (n = 6) in a factorial study design. Each of the 4 diets contained 69% fresh mixed legume-grass herbage, 13% grass hay, and 5% concentrate on a dry matter (DM) basis. Two diets were based on immature fresh mixed legume-grass herbage and grass hay (ES), and 2 contained more mature fresh mixed legume-grass herbage and grass hay (LS). Of these, 1 contained 13% vine leaves (VL+) and the other an additional 13% hay (VL-). No significant differences were observed in DM intake or milk yield across the diets. Methane emission intensity was lowest with ES-VL+ diets compared with LS-VL- diets (-30%; 17.1 vs. 24.5 mg/kg of energy-corrected milk). Methane yield decreased by 17% and 20% when related to the intake of DM and digested organic matter for ES-VL+ compared with LS-VL- diets (16.9 vs. 20.3 g/kg of DM intake; 23.5 vs. 29.3 g/kg of digestible organic matter). Immature grass and vine leaf addition each caused about half of the respective declines. Cows consuming any of the ES diets and the LS-VL+ diet consumed and excreted (urinary N) significantly more N than those consuming LS diets. However, when related to N intake, no differences were recorded. Unexpectedly, vine leaves did not mitigate urine N excretion; however, they lowered the n-6:n-3 ratio and increased concentrations of vaccenic and rumenic acids in both ES and LS diets. Our results demonstrate that feeding immature herbage in combination with vine leaves reduces methane yield; however, the associated high urinary N losses need to be addressed.

Effect of phenological stage and proportion of fresh herbage in cow diets on milk fatty acid composition

Abstract The aim of this work was to test the effect of herbage phenology on the fatty acid (FA) composition of milk and its interaction with fresh herbage proportion in cow diets in controlled conditions, as well as to validate the results in on-farm conditions. Three experiments were conducted in controlled conditions, and were designed to be representative of dairy systems with increasing fresh herbage proportions in cow diets: low (25% of diet dry matter (DM)); high (75% of diet DM), and full grazing (100% of diet DM). The fourth experiment was a survey conducted in commercial farms that adopt feeding systems similar to those of controlled conditions. An overall effect of herbage phenology on milk FA composition was observed. The number of FA that were affected by herbage phenology was higher as the proportion of fresh herbage in the cow diets increased. The C16:0, total even chain saturated FA, odd chain FA, branched-chain FA, C18:1c9, and monounsaturated FA concentrations in milk increased with increasing herbage phenology, whereas the de novo synthesized FA, C18:1t11, CLAc9t11, C18:3 n − 3 and total polyunsaturated FA concentrations decreased. When low proportions of fresh mature herbage was fed to cows, the FA profile of the derived milk differed from the control diet (without fresh herbage) only for the higher concentrations of C18:1t11, CLAc9t11, and C18:3 n − 3, whereas the differences were greater and significant for several FA for similar proportions of fresh herbage at an early phenological stage. The results obtained in controlled conditions were confirmed on-farm: the C18:1t11 and CLAc9t11 were the most sensitive FA to the effect of fresh herbage phenology. However, when low fresh herbage proportion were used in cow diets, the effect of herbage phenology on milk FA concentration was negligible.

Open pasture, silvopasture and sward herbage maturity effects on nutritive value and fermentation characteristics of cool‐season pasture

AbstractIn Appalachian USA, silvopasture offers promise of increased farm productivity. A synchronized, temporal understanding of open pasture (OP) and silvopasture (SP) nutritive characteristics is essential for grazing system development. We examined pasture‐type nutritive‐value relationships when herbage was harvested based on morphological maturity rather than calendar date. Neutral detergent fibre and acid detergent fibre (ADF and NDF) content were greater in silvopasture, while organic matter (OM) was lower (P < 0·05). Digestibility of SP herbage dry matter (DM) and OM tended (P = 0·10) to be lower (418 vs. 471 and 437 vs. 491 g kg−1 respectively). Neutral detergent fibre digestibility was greater (P < 0·05) for OP than SP forage (538 vs. 480 g kg−1), and ADF tended to be greater (P = 0·10; 551 vs. 501). Open‐pasture forage fermentation effluent exhibited slightly higher microbial richness and Shannon diversity than SP. However, overall community composition of both bacteria and archaea did not differ between pasture types or sampling times. Pasture types show proximate analyses differences generally favourable to OP, although both have similar overall nutritive value. In addition, the SP sward exhibited a 4‐ to 6‐days delay in reaching equivalent maturity. Conversion of farm woodlots to SP would increase overall herbage production and improve pasture management flexibility.

Effect of Harvesting Gliricidia Sepium at Different Cutting Frequencies on Quantity and Quality of Herbage Biomass for Dairy Cattle Nutrition.

Herbage quantity and quality response of Gliricidia sepium to pruning intervals (1.0 to 6.0 months) was evaluated. Chemical composition of coppice re-growth was estimated and herbage was incubated in three rumen fistulated Friesian steers for 3, 6, 12, 24, 48, 72, 96 and 120 h. Herbage dry matter yield tended to follow linear response (P= 0.0689) with increasing coppice re-growth maturity and ranged between 36.2 tones/ha/year to 49.1 tones/ha/year. Protein content (291 g/ kg DM to 220 g/kg DM) decreased following a quadratic trend. However, fibre content increased following a curvilinear trend as herbage matured but levels of lignification increased linearly with delayed harvesting. Additionally, fraction ‘b’ of dry matter degradability (548 to 716 g/kg DM) decreased linearly with herbage maturity. Herbage potential degradability (a+b) (926 to 785 g/kg CP) was indicative of high protein solubility and rumen degradable protein (RDP) decreased with increasing maturity. Consequently, microbial protein synthesis and net energy of lactation (NEL) decreased linearly while rumen undegradable protein (RUP) and digestible undegradable protein (DUP) increased linearly with increasing herbage maturity. These results are interpreted to mean that G. sepium herbage quantity and quality is influenced by pruning management.

In vitro rumen methane output of red clover and perennial ryegrass assayed using the gas production technique (GPT)

The in vitro rumen methane output of perennial ryegrass (receiving 0 or 150kg of inorganic fertiliser N/ha/growth) and two red clover varieties (Merviot and Ruttinova) at three different harvests (early and late primary growths, and an autumn regrowth) was assayed using the gas production technique (GPT). Herbages were produced within a randomised complete block (n=4) design experiment conducted over two consecutive years. The forage samples selected from this field plot experiment were arranged in a 4 (herbages)×3 (harvests) factorial structure of treatments. Dried milled herbage samples were incubated at 39°C in a buffered medium inoculated with rumen fluid obtained from fistulated steers. Effects on methane output, feed disappearance, volatile fatty acid (VFA) output and other fermentation variables were evaluated 24h after inoculation. Red clover (mean of the two varieties) had a lower (P<0.001) methane output per g of feed incubated (CH4/DMi) than perennial ryegrass (mean of both treatments) but this effect was reversed (P<0.05) when methane outputs were expressed relative to feed disappeared (CH4/DMd). No differences in methane output were detected between the two red clover varieties (Merviot and Ruttinova) reflecting their similar chemical composition. The application of inorganic N fertiliser to ryegrass reduced (P<0.05) CH4/DMi resulting in similar output to the red clover. Mature herbage from the primary growth, and the autumn regrowth, had lower (P<0.05) CH4/DMi than immature herbage from the primary growth. The lowest (P<0.05) CH4/DMd was associated with the autumn regrowth and was probably due to the presence of non-fermentable soluble compounds in the sward. Overall, a reduction in the in vitro rumen methane output was observed with (1) red clover compared to perennial ryegrass, (2) nitrogen-fertilised compared to non-fertilised perennial ryegrass, and (3) mature primary growth or autumn regrowth compared to immature primary growth. The reduction in methane output was associated with a decline in the extent of fermentation of the herbage as indicated by reduced VFA production. In addition, an increase in the nitrate concentration of fertilised ryegrass could have played an important role in the reduction of methanogenesis by decreasing the availability of hydrogen.

Correlation between δ 13C and δ 15N in C 4 and C 3 plants of natural and artificial sand-binding microhabitats in the Tengger Desert of China

Carbon isotope ratio (δ 13C) and nitrogen isotope ratio (δ 15N) of leaf in shrubs and overground matter in herbage were measured on plant species occurring in different aged artificial sand-binding microhabitats, as well as in natural habitat at the south-eastern margin of the Tengger Desert, China. Both δ 13C and δ 15N of C 3 and C 4 plants varied widely (− 28.12 ≤ δ 13C (‰) ≤ − 23.77 and − 4.45 ≤ δ 15N (‰) ≤ 3.66 for C 3 species, respectively; and − 15.79 ≤ δ 13C (‰) ≤ − 12.63 and − 7.56 ≤ δ 15N (‰) ≤ 1.08 for C 4 species, respectively), representing the different photosynthetic pathway (C 3/C 4) environmental controls. The relative abundance of C 4 species increased over the development of the sand-fixing vegetation, and the significant differences among sites in δ 15N of C 4 plants were found. Among the microhabitats, the isotopic pattern of artificial sand-fixing community is a cluster compared to that of natural vegetation and transitional zones in C 4 plants; however, this pattern of C 3 plants is different significantly. The biological soil crust had significant effect on δ 13C of C 3 plants, not for δ 13C of C 4 plants and δ 15N of both C 3 and C 4 species. Our results also describe a distinct pattern of dual-isotopic signatures, which indicated that a different water-use source and soil nitrogen compartment occurred and may promote the coexistence of different life forms in extreme poor water and nutrients ecosystems. With respect to C 4 plants, the gramineous plants based on family — level exhibit obviously negative isotopic values (both δ 15N and δ 13C) than those of chenopodiaceous plants, indicating a high water-use efficiency of gramineous C 4 plants and more 15N depleted, and these differences may be a result of different functional groups of C 4 species. For C 3 plants, the chenopodiaceous species also show more 15N enrichment than those of plants from other families (e.g. composite, leguminous plants and others). Contrast to previous studies, the δ 15N values of leguminous plants were not closer to the δ 15N of atmospheric nitrogen gas, indicating that leguminous plants in research region used nitrogen mainly from other N sources such as soil, rain/dust, not mainly from biological fixed nitrogen. The correlation between δ 13C and δ 15N of C 3 plants (except leguminous plants) were negative significantly ( P = 0.001), while there were positive relationship between δ 13C and δ 15N in C 3 leguminous plants ( P = 0.003) and C 4 plants ( P < 0.0001), indicating that in the water and nutrient limiting region the carbon and nitrogen discriminations are dependent and linked intimately, and vary with the plant species and photosynthetic pathway.

Red clover polyphenol oxidase: Activation, activity and efficacy under grazing

This study investigated red clover polyphenol oxidase (PPO), its: activity, activation from latent into active form, and whether grazing at different levels of herbage maturity could result in sufficient PPO activation to protect proteins and glycerol-based lipid in the rumen. Wild-type red clover with high PPO activity and a mutant red clover with low PPO activity were used in five experiments. Firstly to investigate activation of the latent red clover PPO enzyme either through: protease, substrate ( ortho-diphenols), cell damage or chemically (sodium dodecylsulphate detergent) induced mediation. Secondly PPO's activity at a range of pHs were determined to show how activation method altered the enzymes activity. Finally whether grazing could activate latent PPO and ultimately result in protected protein and glycerol-based lipid in the rumen was investigated. Incubation of extracted red clover PPO enzyme with a range of ortho-diphenols in the presence of oxygen resulted in rapid conversion of the latent to the active form of PPO. This conversion was blocked by the addition of ascorbic acid suggesting that this mechanism requires formation of ortho-quinones. Cell damage was highly correlated with activation of latent PPO and the formation of protein-bound phenols due to mixing of the chloroplastic enzyme with the vacuolar substrate ( ortho-diphenols). The potential for PPO activity to occur during grazing was investigated by measuring the oxygen concentration in red clover boluses and within the rumen and PPO's effect on protein and glycerol-based lipid within red clover boluses. There was a rapid depletion of oxygen from the rumen, limiting the potential for PPO activation and activity to occur to the period of mastication. PPO was shown to be activated in both wild-type and mutant red clover boluses, however, factors such as fibre content and maturity of the red clover herbage (PPO concentration) altered the efficacy of PPO to produce phenol-bound protein. As a result greater protection of glycerol-based lipid in this study was achieved with a prior conditioning (wilting) of the red clover.

Effects of forage species and stage of maturity on bovine milk fatty acid composition

AbstractFive cows were used in a 5×5 Latin square to evaluate the effects of forage type and stage of herbage maturity on milk fatty acid (FA) composition. Four silages were prepared from primary growths of timothy‐meadow fescue and red clover swards at an early and late stage of growth. Treatments consisted of these silages and an additional treatment comprised of an equal mixture of late‐cut grass silage and early‐cut red clover silage. Forages were fedad libitumand supplemented with 9 kg/day of a standard concentrate. Compared with grass silage, red clover silage diets enhanced milk fat monounsaturated FA (MUFA) and polyunsaturated FA (PUFA) content, 18:3 n‐3 in particular, responses that were associated with concomitant reductions in 10:0 to 16:0 concentrations. Decreases in 16:0 and increases in PUFA concentrations were more pronounced for early than late growths of red clover. Even though red clover resulted in marginal increases in total milk fattrans18:1 content, milktrans‐11 18:1 concentrations were lower for red clover than for grass silage diets. It is concluded that replacing grass with red clover silage prepared at an early stage of maturity represents a sustainable nutritional strategy for enhancing the MUFA and PUFA content of milk.

Effects of mountain grassland maturity stage and grazing management on carotenoids in sward and cow's milk

Carotenoids are involved in the sensorial and nutritional values of dairy products. In grazing systems, both herbage maturity stage and grazing management may affect the amount of carotenoid ingested, thus these factors may affect carotenoid concentrations in milk. Two homoge- nous plots of mountain grassland (1.4 and 2.0 ha) were grazed during two cycles of growth by 6 dairy cows in mid lactation, in strip (SG) and rotational grazing (RG), respectively. We monitored the changes in carotenoid concentrations in sward and milk, measured by HPLC twice a week. Seven carotenoids were identified in the sward: violaxanthin, antheraxanthin, epilutein, lutein, zeax- anthin, s-carotene and 13-cis s-carotene. Forage quality decreased throughout the course of the first growth stage, but carotenoid concentration in sward did not significantly change. In early regrowth, forage quality was high and the concentration of s-carotene and xanthophylls also tended to be higher. Carotenoid concentrations in sward were not affected by grazing management, averaging 350 µg per g DM. The carotenoids identified in milk were β-carotene (75%) and lutein (25%). A significant decrease in s-carotene concentration in milk was observed throughout the course of the first growth stage, from 5.37 to 3.87 µg per g fat, whereas it increased to 4.91 µg per g fat in early regrowth. β-carotene concentration in milk was not affected by grazing management, averaging 4.72 and 5.03 µg per g fat for RG and SG, respectively. However, lutein concentration was slightly lower for RG than for SG, averaging 1.39 and 1.74 µg per g fat, respectively. It is concluded that carotenoids in milk were only slightly affected by herbage maturity stage, and to a lesser extent by grazing management. carotenoids / cow's milk / mountain grassland / maturity stage / grazing management

Microbial communities in the phyllosphere of grasses on fenland at different intensities of management

AbstractThe effects of changes from conventional grassland management on fenland in Germany to extensification due to reduced fertilizer inputs and cutting frequency on the microbial colonization in the phyllosphere were investigated. A delay in the first cut for silage and hay, required by a nature conservation programme, was accompanied by the senescence of grasses which significantly influenced certain microbial groups. Heterotrophic bacteria, aerobic and anaerobic spore‐formers, as well as filamentous fungi, showed an increase in population densities on the mature herbage of the later cuts. Differences in the rate of fertilizer application and cutting frequency, which had an effect on the dry‐matter yield, also influenced the population density of heterotrophic bacteria and, in certain circumstances, that of filamentous fungi. Chemical measures of forage quality were highly correlated with the population density of microbial groups and with the maturity of the herbage. In contrast to these results, the population dynamics of further groups of micro‐organisms (yeasts, Micrococcaceae, listeria) did not show any relationship with pasture management.

Methane emissions by Charolais cows grazing a monospecific pasture of timothy at four stages of maturity

In order to examine the relationship between herbage maturity and methane (CH4) emission under conditions which minimized opportunities for selective grazing, six 8-yr-old, dry and early-pregnant Charolais cows [712 ± 22.7 kg liveweight (LW)] were grazed on a mono-specific pasture of timothy at four stages of maturity: early vegetative, heading, flowering, and senescence. Daily CH4 production was measured during 7 d using the sulfur hexafluoride (SF6) tracer-gas technique. Organic matter intake (OMI) was determined from fecal output estimated by Yb2O3 dosing and feed digestibility (OMD) estimated using a fecal N index. The OMD (%) decreased (P &lt; 0.05) from 77.6 at early vegetative to 56.2 at senescence, but no cow effect upon OMD was observed. The OMI (14.8 g kg-1 LW) and CH4 production (273 g d-1) were higher (P &lt; 0.05) at heading than at the other stages of maturity. The proportion of gross energy intake (GEI) lost in CH4 did not differ with maturity (mean 6.4% of GEI). Cow effects upon OMI and CH4 emission were significant (P &lt; 0.05). CH4 production (g d-1) was not related to diet chemical composition or OMD, but was correlated with digestible neutral detergent fiber (NDF) intake (kg d-1) (r = 0.61, P &lt; 0.01). Across all stages of maturity between-cow variation explained 54 to 70% of the total variation in CH4 production. Key words: Methane, cattle, animal variation, timothy, phenology, selective grazing

Comparative digestive ability and microbial population of Sistani (bos indicus) and Holstein (bos taurus) cattle fed different roughage diets

There is conflict regarding the relative abilities of Bos indicus and Bos taurus cattle to digest the feedstuffs. Part of this conflict may have arisen because a wide variety of diets have been fed at different range of intakes and only digestibility in whole tract measured. Generally no attempts have been made to partition rumen and post-rumen digestion or to assess the relative importance of rumen digestion and clearance between diets and between genotypes. Nitrogen (N) is frequently a major limiting nutrient for ruminants specially when they are given diets of mature herbage. On the other hand the extent to which cattle are able to recycle urea-N from blood to rumen for utilization in production of microbial protein could have an important influence on animal survival under condition of severe N limitation. The present experiment was designed to compare rumen microbial population and the end products of rumen fermentation between Sistani (Bos indicus) and Holstein (Bos taurus) breeds.

Whole-crop cereals for grazing and silage: balancing quality and quantity

There has been a marked increase in the use of cereals for supplementary grazing and silage for the developing dairy industry in the South Island. Cereals provide high energy supplement in autumn/winter or can be used as a high fibre source in spring. Variation in yield potential in cultivar trials in Canterbury was assessed for autumn and spring-sown crops. The aim was to produce high quality cereal feeds with good yield potential by examining the variation among species and cultivar selections in well managed trials. Single-bite crops sown in early autumn in Canterbury provide up to 5.5 t/ha herbage DM yield with at least 17.5 % protein, 12% total soluble carbohydrate including starch (TSC) and metabolisable energy (ME) of 11.3 MJ/kg in mid-June. Multiple graze types (eg. Doubletake triticale) with similar winter productivity and quality to single-bite crops produced an additional 13.5 t/ha biomass for a silage crop. At ensiling, this cultivar had 9.3 MJ/kg ME with mean 19.5% total soluble carbohydrates. Spring-sown cereals for silage produced up to 20 t/ha. Harvest timing was a significant factor in the wide range in quality of herbage for ensiling. Cultivar means ranged from 7.0 - 12.8% DM for protein, 8.7- 31.6% DM for TSC and 8.3-10.5 MJ/kg DM for ME. More mature herbage had reduced organic matter digestibility and higher TSC but reduced ensilability at DM content in excess of 40%. Keywords: dairying, fibre, forage, herbage quality, metabolisable energy, near infrared reflectance spectroscopy, supplements

Comparative digestion of herbage by two breeds of sheep: effects of grass maturity stage and level of intake

AbstractTwo trials were conducted to study the effect of the stage of maturity of fresh herbage on its digestibility by two breeds of sheep (Churra v. Merino). The sward consisted of a mixture of grasses and clover, and was harvested either in late May (early cut, EC) or in late July (late cut, LC). In each trial, 12 mature sheep of each breed were used. Each animal received a different amount of fresh herbage, so that levels of food intake ranged between 8·1 and 24·7 g dry matter (DM) per kg body weight per day. EC herbage showed higher crude protein content (116 v. 67 g/kg DM), lower neutral-detergent fibre concentration (494 v. 664 g/kg DM) and higher DM digestibility (0·687 (s.e. 0·005) v. 0·463 (s.e. 0·007)) than the LC herbage. DM digestibility coefficients observed in Churra (0·694 (s.e. 0·028) for EC and 0·476 (s.e.0·028) for LC herbage) tended to be greater than those observed in Merino sheep (0·680 (s.e. 0·021) for EC and 0·452 (s.e. 0·040) for LC herbage). With the EC herbage DM digestibility tended to decrease as the level of intake increased. Samples of dried herbage were incubated in the rumen of Churra and Merino sheep to determine the DM degradability by the in situ technique. Fractional degradation rates (c values) were significantly faster in the rumen of Churra than in Merino (0·046 (s.e. 0·003) v. 0·031 (s.e. 0·002)), with large differences between breeds in the DM disappearance rates at intermediate incubation times, and no significant differences between Churra and Merino sheep in the mean a + b values. Microbial N supply, calculated from the urinary excretion of purine derivatives, was significantly affected by the herbage maturity stage and by the level of DM intake, but not by the breed of sheep. It is suggested that differences between breeds of sheep in food digestibility may be related to their ability to digest fibrous diets.

Effect of Application of Basic Slag and Superphosphate on Herbage Yield and on Soil and Herbage Concentrations of Phosphorus in Organic Grassland

ABSTRACT The experiment was carried out at an organic farm in 1996 and 1997. The purpose of the experiment was to test the effectiveness of basic slag (7% P) as a P fertilizer on an organic perennial ryegrass/white clover sward. Superphosphate (16% P) was used as a standard comparison. There was no difference between fresh weight or dry matter yields of grass or clover or of total herbage yields in plots treated with different rates of basic slag or superphosphate in the first harvest at the end of July 1996. In the second harvest, recorded at the end of August 1996, increasing rates of P gave increased yields. P source had no effect on herbage fresh weight or dry matter yield. P source and rate of P application had no effect on herbage yield in 1997. The percentage dry matter in herbage was unaffected by P source. Increasing rates of basic slag and superphosphate had no effect on the percentage dry matter in the herbage. There was no difference in the soil P concentrations obtained with basic slag or superphosphate when these were applied at equivalent rates. Increasing rates of P, when applied as basic slag or superphosphate at rates of 7, 14 and 28 kg ha−1, gave an increase in soil P concentration at 128 days after application. No increase was recorded at 531 days after application. Superphosphate gave the largest initial increase in herbage concentrations of P but was no more effective at raising the soil and herbage concentrations of this element than equivalent rates of basic slag over a two year period.

The effect of changing patterns of fertilizer applications on the major mineral composition of herbage in relation to the requirements of cattle: a 50-year review

Abstract Annual surveys of fertilizer practice have been conducted since 1942. Since 1985, nitrogen application rates to grass have progressively declined and phosphorus application has been reduced since the mid 1970s. Increasing environmental issues and the present interest in organic farming and low input systems indicate that these trends will continue. Present overall fertilizer use for grazing on dairy farms is about 170 kg N, 10 kg P and 20 kg К per ha. Higher rates are used for intensive silage production, 200 kg N, 15 kg P and 50 kg К per ha. In contrast, recommended applications are 340 kg N, 18 kg P and 25 kg К per ha for grazing and 380 kg N, 40 kg P and 260 kg К per ha for intensive silage. Herbage yield is controlled by the amount and timing of nitrogen fertilizer applications. The major mineral content depends on herbage maturity within the growth cycle; both phosphorus and potassium contents fall with declining crude protein concentrations. Nitrogen fertilizer generally increases both magnesium and sodium concentration whilst potassium application decreases both. The overall effect of combined applications is to minimize changes. In the critical spring and autumn periods, herbage dry-matter intakes may be as important as magnesium content and availability when assessing the risk of hypomagnesaemia in the grazing cow. Fertilizers, including phosphorus, even in the long term, have little effect on the calcium and phosphorus contents of herbage. Nitrogen and phosphorus concentrations are significantly ocrrelated in grazed herbage, silage and hay. If environmental or economic policies were to result in a reduction in the crude protein content of grazed herbage from ca. 250 to ca. 200 g/kg dry matter, the phosphorus intake of a cow giving 30 kg milk per day would fall by 0·5 g/kg dry-matter intake. This, together with any desirable additional magnesium, should preferably be given as an oral mineral supplement rather than by attempting to modify the mineral content of herbage.

Energy Value and Protein Content of Hays Made on Farms in England and Wales 1984–1995

A total of 4154 samples of hay made on commercial farms between 1984 and 1995 were analysed to investigate the annual variation in protein and energy content. The average crude protein (CP) content was 96 (s.d. 29·1)g/kgd.m. and predicted metabolizable energy (ME) 8·8 (s.d. 0·77)MJ/kg d.m. There was significant (P<0·001) year-to-year variation in CP and ME content. The results indicated that the average quality was moderate, because the hay was usually made from mature herbage which had been weathered in the field during making.

Seed yield and hardseededness of two amphicarpic pasture legumes (Vicia sativa ssp. amphicarpa and Lathyrus ciliolatus) and two annual medics (Medicago rigidula and M. noeana)

SUMMARYYields and hardseed breakdown of underground and aerial seeds in subterranean vetch (Vicia sativa ssp. amphicarpa) and lathyrus (Lathyrus ciliolatus) and aerial seeds of Medicago rigidula and M. noeana were compared at Tel Hadya, near Aleppo, in north Syria between 1990 and 1992. Underground and aerial seed and straw (mature herbage) yields were measured at maturity in the first spring, and hardseed breakdown over the following summer, autumn and winter. Regenerating herbage production was measured in the second spring.In the establishment year (292 mm rainfall) the medics produced twice as much straw as the amphicarpic species. In contrast, seed yields were less than half: M. rigidula and M. noeana produced 412 and 110 kg/ha respectively, while subterranean vetch and lathyrus produced 1174 and 736 kg/ha. More than 95 % of the total seed yield of the amphicarpic legumes was underground. Underground seeds of the amphicarpic legumes were larger than aerial seeds, and almost 10 times as large as the medic seeds.Seeds of all species were &gt; 90% hard when newly set in summer. At the first seasonal rains &gt; 95% of underground seed had softened, compared with 5 and 40% of the aerial seeds of vetch and lathyrus respectively. The medics remained &gt; 90% hardseeded. In laboratory tests, embryo dormancy was observed in all species prior to the onset of first seasonal rains. For the amphicarpic legumes, but not for the medics, embryo dormancy persisted into winter. In the field, and after all germination events, 900–1430 seeds/m2 of subterranean vetch seed remained in the soil. This was considerably more than expected, based on the low levels of hardseededness and embryo dormancy observed in the laboratory. The results suggest that dormant seeds of the amphicarpic legumes need light to germinate.In the second year (353 mm rainfall), regenerating M. rigidula produced 5·3 t/ha compared with 3·4 t/ha by the best subterranean vetch from approximately equal numbers of seedlings. The amphicarpic legumes germinated later and over a more extended period than the medics, indicating that they could become weeds in a cereal/pasture rotation. However, the results suggest that in drier areas or in drier years the vetches will compare favourably with the medics in most respects. Clearly, subterranean vetch and lathyrus have great potential for pasture improvement in dry areas.

Influence of defoliation on some aspects of regrowth and senescence of Persian clover herbage grown in pots

This experiment investigated the effects of defoliation management of Persian clover (Trifolium resupinatum) on herbage production, and in particular, regrowth and losses of production due to senescence. Three heights of defoliation of Persian clover (0, 5, 10 cm above soil level) were superimposed on 3 frequencies of defoliation (4, 6, 12 weeks between harvests until early October; 3, 4.5, 9 weeks subsequently) in a completely randomised pot experiment with 3 replicates. Defoliation management had a large effect on yield of harvested herbage, in agreement with earlier studies with Persian clover in mixed swards or as a monoculture in the field. The amount of herbage that grew below defoliation height and subsequently died was 0-21% of the total herbage grown. The amount of dead and dying matter in herbage above and below defoliation height increased as both defoliation height and interval increased. This represented up to 61% of the total herbage grown. Aspects of regrowth (leaf area, petiole number, petiole extension rate, yield of herbage during growth, biomass of root relative to shoot) were measured. Except at very long defoliation intervals, vegetative growth of Persian clover herbage was positively associated with all of the above variables. The pattern of change with time in the rate of green herbage accumulation following defoliation reflected the balance between changes in the growth of new plant tissue and the loss of mature tissue to senescence and decomposition.