The nutritive value of Prangos ferulacea

This study was conducted to determine the chemical composition and nutritive value of Prangos ferulacea, a plant found in the Mediterranean and Middle‐east regions, where it is used as animal fodder. Samples of mature plants were collected from S.E. Turkey. Metabolizable energy (ME) values were estimated from in vitro gas production measurements and from chemical composition. ME concentrations of the whole plant, leaves and stems were estimated to be 12·2, 11·9 and 12·7 MJ kg^?1 dry matter (DM) respectively, which compares favourably with high‐quality forages commonly used in ruminant feeding. The DM degradability of the whole plant, leaves and stems increased up until 48 h of in situ incubation, 866, 915 and 784 g kg^?1 DM respectively, but changed little between 48 and 72 h. In vitro DM and organic matter digestibility of the whole plant, leaves and stems were 0·769 and 0·806, 0·773 and 0·790, and 0·740 and 0·840 respectively. The results show that P. ferulacea may be regarded as a high‐energy forage, but further research is needed on its intake characteristics and the levels of animal performance that can be achieved from its inclusion in the diet.     

Chemical composition and nutritive value of leaves and stems of tropical weed Chromolaena odorata

Chromolaena odorata (Siam weed) has been classified as a weed plant in West Africa. Data from C. odorata foliage after 4, 6, 8, 10 and 12 weeks of regrowth showed that the leaf fraction had a crude protein content above 194 g kg^–1 dry matter (DM) and an average leaf to stem ratio of 2·1:1. Chemical analysis of the leaf fraction of an 8‐week‐old regrowth indicated a high crude protein content (258 g kg^–1 DM) and a high degradable nitrogen content (60·7 g N kg^–1 digestible organic matter), but low neutral‐detergent fibre (331 g kg^–1 DM), acid‐detergent lignin (53·1 g kg^–1 DM), total extractable phenolic (37·1 g kg^–1 DM), extractable tannin (0·72 absorbance at 550 nm) and extractable condensed tannin (1·4 g kg^–1 DM) contents. In sacco degradability analysis of the 8‐week‐old regrowth leaf sample showed a high 48 h organic matter (935 g kg^–1 DM) and crude protein (953 g kg^–1 DM) degradability. The leaf sample had an organic matter degradability of 670 g kg^–1 DM as estimated by cumulative gas production in vitro after 24 h incubation. There was little or no phenolic‐related antinutritive factors in C. odorata. Additionally, leaf samples had no effect on rumen protozoa activity estimated as the rate of [¹⁴C]leucine Selenomonas ruminantum bacterial protein breakdown. Data from this study suggest that C. odorata leaves are of high nutritive value and might have the potential to be used as a protein supplement to ruminants. There is need for further investigation to test whether C. odorata leaves may have any deleterious effect on the host animal.     

Production, survival and nutritive value of the perennial legumes Dorycnium hirsutum and D. rectum subjected to different cutting heights

Dorycnium hirsutum and D. rectum are perennial legumes which may have potential for use as pastures for the control of groundwater recharge in southern Australia. Little is known about the quality of the forage of Dorycnium species for grazing livestock or how these species respond to cutting. The effect of cutting height on plant survival, production of dry matter (DM), the proportion of leaf, edible stem (approximately <5 mm diameter) and woody stem in the DM and the nutritive value of the edible components was investigated. Biomass above five cutting‐height treatments (uncut, ground level, 5–8 cm, 10–15 cm and 15–30 cm above ground level) was removed at 8‐week intervals from plots of D. hirsutum and D. rectum from September 2002 to July 2003. In both species, plants subjected to lower cutting height treatments produced less DM above the height of the cut than those cut at higher heights. DM production declined over time in all treatments. Plants cut to ground level failed to regrow after the second harvest in D. hirsutum and the fourth harvest in D. rectum. Thus, these Dorycnium species were susceptible to high severity defoliations at 8‐week intervals. Negligible inedible woody stem was present in regrowth of both species after 8 weeks but D. hirsutum regrowth had a higher proportion of leaf (0·72) than D. rectum (0·56). Plants left uncut accumulated a large proportion of inedible woody stem in the DM (0·69 in both species) by July 2003, particularly at the base of the plant. Edible DM from regrowth of D. hirsutum and D. rectum had crude protein (CP) concentrations of 120 and 150 g kg^?1 DM; dry matter digestibility (DMD) values of 0·45 and 0·58; organic matter digestibility (OMD) values of 0·50 and 0·64; neutral‐detergent fibre (NDF) concentrations of 370 and 290 g kg^?1 DM; and acid‐detergent fibre (ADF) concentrations of 260 and 210 g kg^?1 DM, respectively. Medicago sativa, grown under similar conditions, had higher digestibility values (0·63 DMD and 0·66 OMD) and similar CP concentrations to D. rectum (140 g kg^?1 DM), but higher concentrations of NDF and ADF (410 and 290 g kg^?1 DM). Leaf material from both Dorycnium species had a higher nutritive value than edible stems, with DMD and OMD values of leaf of D. rectum being 0·68 and 0·74 respectively. Uncut plants had a much lower nutritive value of edible DM than the regrowth from cut treatments; older material was also of a lower nutritive value. The relatively low nutritive value of even the young regrowth of Dorycnium species suggests that forage quality is a major limitation to its use. Forage of Dorycnium species could be used during periods when other sources of forage are in short supply but infrequent grazing it is likely to produce forage of a low nutritive value.     

Analysis of the nutritive value of timothy grown with varying N nutrition

Nitrogen fertilization affect growth and yield of timothy (Phleum Pratense L.), but there are conflicting report on its effect on nutritive value. Two experiments were conducted to describe changes in nutritive value of field-grown timothy fertilized with four rates of N fertilizer during spring and summer growth cycles, and to analyse relationships between parameters of nutritive value and the leaf to weight ratio (LWR). Early in the regrowth cycles when the harvestabe shoot biomass was approximately 200 g dry matter (DM) m^?2 and under non-limiting N and water conditions, the in vitro true digestibility (IVTD) of DM was greater in spring than in summer because the concentration of neutral-detergent fibre (NDF) was lower and its in vitro cell wall digestibility (IVCWD) was greater. However, the rates of decline in IVTD and IVCWD and the rate of increase in NDF were greater in spring than in summer. Nitrogen deficiency decresed IVTD and IVCWD, and increased NDF concentration early in the regrowth cycles. Nitrogen deficiency, however, reduced the rate of change in the three parameters of nutritive value. By the end of growth cycles, IVTD was 59 and 42 g kg^?1 DM greater when no N was applied than with non-limiting N conditions in spring and summer respectively. When no N was applied, the IVCWD was 76 and 52 g kg^?1 NDF greater, whereas the NDF concentration was 35 and 42 g kg^?1 DM less than under non-limiting N conditions in spring and summer respectively. The N deficiency increased the proportion of leaves in the biomass, which can explain for the most part the positve effect of the N deficiency on the nutritive value of timothy. This positive effect of the N deficiency on nutritive value though the proportion of leaves in the biomass, however, was reduced by the negative effect of N deficiency on the nutritive value of leaves or stems or both.     

In vitro rumen methane output of perennial ryegrass varieties and perennial grass species harvested throughout the growing season

The selection and feeding of perennial ryegrass (Lolium perenne L.) varieties (PRV) or perennial grass species (PGS) may affect enteric methane (CH₄) output because of changes in the fermentation dynamics in the rumen as a result of differences in herbage chemical composition. The objective of this study was to determine the effects of PRV and PGS harvested throughout the growing season on herbage chemical composition, and in vitro rumen fermentation variables and CH₄ output per unit of feed using a batch culture technique. Seven PRV (Experiment 1: Alto, Arrow, Bealey, Dunluce, Greengold, Malone, Tyrella) and six perennial grasses [Experiment 2: perennial ryegrass (Navan), perennial ryegrass (Portstewart), cocksfoot, meadow fescue, tall fescue, timothy; defined as PGS], managed under a simulated grazing regime, were incubated for 24 h with buffered rumen fluid in two separate experiments. The CH₄ output per unit of feed dry‐matter (DM) incubated was not affected (P > 0·05) by PRV (range of mean values across PRV of 23·9–25·3 (SEM 0·41) mL g^?1 DM) or by PGS (25·6–26·6 (SEM 0·37) mL g^?1 DM). The CH₄ output per unit feed DM disappearing during the in vitro rumen incubation was not affected by PRV (33·9–35·1 (SEM 0·70) mL g^?1 DM), and although there was an overall PGS effect (P < 0·05; 37·2–40·3 (SEM 0·71) mL g^?1 DM), none of the paired contrasts between PGS were significant when analysed using Tukey adjusted comparisons. This outcome reflected either small‐scale or a lack of treatment effects on individual herbage chemical composition (e.g. 454–483 g NDF kg^?1 DM, 215–224 g CP kg^?1 DM and 94–122 g water‐soluble carbohydrate (WSC) kg^?1 DM across PRV; 452–506 g NDF kg^?1 DM, 208–243 g CP kg^?1 DM and 73–131 g WSC kg^?1 DM across PGS) and in vitro rumen fermentation variables. Hence, these results provide no encouragement that choices among the grasses examined, produced within the management regimes operated, would reduce enteric CH₄ output per unit of feed in vivo. However, the technique utilized did not take account of animal × PRV or PGS interactions, such as potential differences in intake between animals, that may occur under farm conditions.     

Effect of defoliation management, based on leaf stage, on perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under dryland conditions. 2. Nutritive value

A field experiment was undertaken between April 2003 and May 2004 in southern Tasmania, Australia, to quantify and compare changes in the nutritive value of perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under a defoliation regime based on stage of leaf regrowth. Defoliation interval was based on the time taken for two, three or four leaves per tiller to fully expand. At every defoliation event, samples were collected and analysed for acid‐detergent fibre (ADF), neutral‐detergent fibre (NDF) and total nitrogen (N) concentrations and to estimate metabolizable energy (ME) and digestible dry matter (DDM) concentrations. Amounts of crude protein (CP) and metabolizable energy (MJ) per hectare values were subsequently calculated. There was a significantly lower (P < 0·001) NDF concentration for perennial ryegrass compared with prairie grass and cocksfoot, and a significantly lower (P < 0·001) ADF concentration for cocksfoot compared with prairie grass and perennial ryegrass, regardless of defoliation interval. The CP concentration of cocksfoot was significantly greater (P < 0·001) compared with the CP concentrations of prairie grass and perennial ryegrass. The estimated ME concentrations in cocksfoot were high enough to satisfy the requirements of a lactating dairy cow, with defoliation at or before the four‐leaf stage maintaining ME concentrations between 10·7 and 10·9 MJ kg^?1 DM, and minimizing reproductive plant development. The ME concentrations of prairie grass (10·2–10·4 MJ kg^?1 DM) were significantly lower (P < 0·001) than for cocksfoot (as above) and perennial ryegrass (11·4–11·6 MJ kg^?1 DM) but a higher DM production per hectare resulted in prairie grass providing the greatest amounts of ME ha^?1.     

Changes during growth in the nutritive value of components of berseem clover (Trifolium alexandrinum L.) under different cutting treatments in a Mediterranean region

The nutritive value of berseem clover (Trifolium alexandrinum L.) may be influenced by changes in the nutrient concentrations of morphological fractions as a consequence of cutting treatment. The aim of this study was to evaluate the effects of different cutting treatments on the nutritive value of herbage and leaf and stem components in two Mediterranean berseem genotypes during growth in order to develop management approaches for harvesting forage with a high nutritive value. Spring growth of genotypes of Egyptian (cv. Giza 10) and Italian (cv. Sacromonte) origins was harvested in each of 2 years beginning 196 days after sowing and thereafter every 6 days (twelve harvests in total) to measure dry matter (DM) yield and nutritive value. Cutting treatments were initiated at sixth internode elongation (A) and early flowering (B) and there was an uncut control treatment (C). In vitro digestibility of organic matter (IVOMD) and crude protein (CP) concentration were determined for leaf, stem and total forage of each cultivar at each harvest. For both cultivars, in the uncut treatment (C), DM yield increased linearly to a maximum of 14 800 kg ha^?1, on average, by 250 days after planting, the same time at which stem DM accumulation peaked, whereas the nutritive value, in terms of IVOMD and CP concentration, declined with age, coinciding with a reduction in leaf:stem ratio (LSR) from 1·00 to 0·30. Plant parts differed (P < 0·01) in nutritive value with stems being of lower nutritive value than leaves, in the two cutting treatments. There were strong positive correlations between LSR and herbage IVOMD and CP concentration, in both cutting treatments, indicating that, during growth, part of the changes in IVOMD and CP concentration of berseem clover plants was due primarily to the changes in the LSR. Defoliation induced a considerable reduction in DM yield, but an increase in the LSR and a small increase in nutritive value. Plants cut at the sixth internode elongation (A) showed a small proportional decrease (0·19) in total DM yield, but higher LSR values and similar or higher IVOMD and CP concentration than initiating cutting at early flower (B). Delaying defoliation to the early flowering stage (B) increased the proportion of stems and, therefore, decreased nutritive value. Therefore, harvest management in which cuts are applied at the stage of sixth internode elongation appears to be the most favourable for obtaining relatively high yields of forage with high nutritive value in berseem clover grown in Mediterranean regions.     

Changes in the physiology and feed quality of cocksfoot (Dactylis glomerata L.) during regrowth

Abstract A glasshouse study was undertaken to determine the physiological and morphological changes in cocksfoot (Dactylis glomerata L.) during regrowth after defoliation. Individual plants were arranged in a mini‐sward in a randomized complete block design. Treatments involved harvesting each time one new leaf had expanded (one‐leaf stage), up to the six‐leaf stage, with the plants separated into leaf, stubble (tiller bases) and roots. Stubble and root water‐soluble carbohydrate (WSC), stubble and leaf dry matter (DM), tiller number per plant and leaf quality (crude protein (CP), estimated metabolizable energy (ME) and mineral content) were measured to develop optimal defoliation management of cocksfoot‐based pastures. WSC concentration in stubble and roots was highest at the five‐ and six‐leaf stages. Mean WSC concentration (g kg^?1 DM) was greater in stubble than roots (32·7 ± 5·9 vs. 9·4 ± 1·5 respectively). There was a strong positive linear relationship between plant WSC concentration and leaf DM, root DM and tillers per plant after defoliation (Adj R² = 0·72, 0·88 and 0·95 respectively). Root DM plant^?1 and tiller DM tiller^?1 decreased immediately following defoliation and remained low until the three‐leaf stage, then increased from the four‐leaf stage. Tillers per plant remained stable until the four‐leaf stage, after which they increased (from 9·9 ± 0·5 to 15·7 ± 1·0 tillers plant^?1). Estimated metabolizable energy concentration (MJ kg^?1 DM) was significantly lower at the six‐leaf stage (11·01 ± 0·06) than at any previous leaf regrowth stage, whereas CP concentration (g kg^?1 DM) decreased with regrowth to the six‐leaf stage. Both the levels of ME and CP concentrations were indicative of a high quality forage throughout regrowth (11·37 ± 0·04 and 279 ± 8·0 for ME and CP respectively). Results from this study give a basis for determining appropriate criteria for grazing cocksfoot‐based pastures. The optimal defoliation interval for cocksfoot appears to be between the four‐ and five‐leaf stages of regrowth. Delaying defoliation to the four‐leaf stage allows time for replenishment of WSC reserves, resumption of root growth and an increase in tillering, and is before herbage is lost and quality falls due to onset of leaf senescence.     

Effect of extent and rate of wilting on nitrogen components of grass silage

Wilting grass prior to ensiling generally increases the dry matter (DM) intake but the effect of wilting on animal performance is still poorly understood. There is a need to improve understanding of the effects of wilting on the nutritional components and chemical composition of grass silage. This study focused on the effects of the extent and rate of wilting on N components of grass silage. Meadow grass was wilted to four DM contents (200, 350, 500, 650 g kg^?1) at two different rates (fast, slow), creating a total of eight silages. Crude protein (CP) fractions were measured using the Cornell Net Carbohydrate and Protein System. Utilizable CP at the duodenum (uCP), a measure of feed protein value, was estimated using the modified Hohenheim gas test. Ruminally insoluble, undegraded feed CP (RUP) was measured using an in situ technique. Amino acid (AA) composition prior to and after rumen incubation was also investigated. Utilizable CP at the duodenum, RUP and true protein fractions B2 and B3 were increased by rapid wilting and high DM content (DM > 500 g kg^?1), although the increase with DM was only mild for uCP, probably due to lower ME content in the DM‐650 silages. Non‐protein‐N decreased with increasing DM and rapid wilting. The higher RUP content from both DM‐650 silages leads to a higher total AA content after rumen incubation. Treatment also influenced the AA composition of the ensiled material, but the AA composition after rumen incubation was similar across treatments. Rapid and extensive wilting (DM > 500 g kg^?1) improved protein value and reduced CP degradability. Increased uCP may result in higher milk protein yield, while reduced degradability may reduce N lost from urinary excretion. The primary effect of wilting on post‐ruminal AA supply from RUP appeared to be quantitative, rather than qualitative.     

Effects of incorporating cowpea in a subtropical grass pasture on forage production and quality and the performance of cows and calves

The increasing cost of N fertilizer has stimulated an interest in sourcing protein from warm‐season legumes among beef cattle producers in the tropical/subtropical areas of the world. The objective of this study was to evaluate effects of two strategies of incorporating cowpea [Vigna unguiculata (L.) Walp.] into bahiagrass (Paspalum notatum Flügge) pastures on the herbage characteristics and performance of grazing cow–calf pairs. The study was conducted in Ona, Florida, USA, from May to August in 2007 and 2008. Experimental units were 1·0 ha. Treatments were bahiagrass pasture alone (control), 50:50 bahiagrass–cowpea pasture (cowpea), bahiagrass pasture with a cowpea creep grazing area (0·1 ha, creep grazing) and bahiagrass pasture with a creep‐fed concentrate [(creep feeding; 10 g kg^?1 body weight (BW)]. The cowpea pastures had lower herbage mass [HM, 1·8 vs. 3·7 t ha^?1] and herbage allowance [HA, 0·8 vs. 1·4 kg DM kg^?1 live weight (LW)] compared with the other treatments. Cowpea had greater CP (CP, 160 g kg^?1) and in vitro digestible organic matter (IVDOM), (600 g kg^?1) than bahiagrass (110 and 490 g kg^?1 respectively); however, cowpea HM was only 0·9 t ha^?1 in May and 0·7 t ha^?1 in June, but it did not persist in July and August. Calves receiving the creep feeding treatments had greater average daily gain (0·8 vs. 0·7 kg d^?1) than calves in other treatments. Further research is necessary to exploit the superior nutritive value of cowpea in grazing systems in the south‐eastern USA.     

Supplementary feeding of grazing beef cattle

The effects of cereal and protein supplements on feed intake and liveweight gain were studied. In 1975, steers were continuously stocked on autumn pasture and fed no supplement or 8 g dry matter (DM) per kg liveweight (LW) per d as rolled barley (crude protein (CP) concentration 120 g kg^-1), lucerne cobs (CP concentration 190 g kg^-1) or a mixed concentrate (CP concentration 300 g kg^-1). In 1976, steers were continuously stocked or rotationally grazed in summer and fed no supplement or 7 g DM per kg LW per d as either rolled barley (CP concentration 130 g kg^-1) or a mixture of rolled barley and groundnut meal (CP concentration 210 g kg^-1). Herbage organic matter (OM) intakes in 1975 and 1976 were depressed on average by 22 and 15% respectively with supplementation, but total OM intakes were increased by 9 and 15% respectively. Daily liveweight gain was not significantly increased by supplementation in 1975 when herbage allowance was ample but was significantly increased in 1976 when herbage allowance was limited and herbage digestibility was lower. Protein concentration of the concentrate did not significantly affect daily gain in either year nor was there any difference in gain between rotational grazing and continuous stocking.     

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.     

Effect of harvest time on yield and pre-harvest quality of semi-leafless grain peas (Pisum sativum L.) as whole-crop forage

The aim of the work was to study changes in the yield and nutritional characteristics of whole crop semi-leafless field pea over two growing seasons in the Po plain, Italy. Samples of two cultivars (Baccara and Sidney) were collected from flowering to grain maturity. The developmental stage, yield, dry matter (DM) content, crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), starch, water soluble carbohydrates (WSC), gross energy (GE), organic matter digestibility (OMD) and the net energy for lactation (NE_L) were determined at each harvest. The forage characteristics were regressed on the growing degree days (GDD) with 4.4 °C as the base temperature. The DM yield increased with advancing maturity from 0.5 to 8.91 Mg ha⁻¹, while the CP decreased from 261 to 159 g kg⁻¹ DM. During the whole growth cycle the GE, OMD, NE_L and milk forage units (milk FU) were almost steady. No differences were observed between the cultivars for any of the measured parameters. At grain maturity, the crop produced over 4.0 Mg ha⁻¹ DM of grain. The CP, starch and WSC of the grain did not show any differences between the cultivars or years. The data showed that the nutritive quality of the forage of the semi-leafless grain pea harvested as a whole crop for ensiling purposes did not diminish with maturity and could help improve the self-sufficiency of dairy farms, in terms of home-grown protein forages.     

Seasonal productivity and nutritive value of temperate grasses found in semi-natural pastures in Europe: responses to cutting frequency and N supply

Monocultures of thirteen perennial C₃ grass species that co‐occur in temperate semi‐natural grassland communities in Europe were compared in a factorial field design of two levels of N supply and two levels of cutting frequency. Above‐ground yield of dry matter (DM), crude protein (CP) concentration and pepsin‐cellulase DM digestibility of herbage were measured in two successive years. Species was the largest source of variability in yield of DM and DM digestibility of herbage, while CP concentration of herbage responded more to management factors. The highest mean DM yields and values of DM digestibility of herbage were achieved in spring for Festuca arundinacea and in autumn for Phleum pratense. Poa trivialis and Festuca rubra had the lowest DM yield and DM digestibility values, respectively, regardless of seasons and treatments. For all species CP concentration in herbage increased in response to an increase in cutting frequency and N supply by an average of 46 and 34 g kg^?1 DM respectively. Differences between years and seasons indicated the importance of plant phenology on nutritional variables and the influence of environmental factors on species performance. Species ranking was compared according to their annual digestible DM and CP yields. The results show that some grasses have a nutritive value which is comparable to that of forages selected for high yields.     

Effects of nitrogen application rate on productivity,nutritive value and winter tolerance of timothy and meadow fescue cultivars

Finnish N fertilizer application regulations for forage grasses are based on field experiments mainly conducted in the 1960–1970s with cultivars and management practices typical of the time. In order to update the yield response function of N, to make it better suited to current grassland farming, field experiments were conducted at two sites in 2015–2017 with two cultivars of timothy (Phleum pratense L.) and one of meadow fescue (Festuca pratensis Huds.). Dry matter (DM) yield, nutritive value and N balance were evaluated, with N application levels 0, 150, 200, 250, 300, 350, 400 and 450 kg N ha⁻¹ year⁻¹. The grasses were harvested three times per season. The data indicate that the DM yield response was significantly stronger, and N was used more efficiently for DM production than earlier without compromising the nutritive value, especially during the first two years. The third harvest produced on average 23% of the annual yield, utilizing N efficiently. N application rates below 350 kg N ha⁻¹ year⁻¹ did not cause substantial overwintering losses or lodging. The data indicate that with changing climate and improved cultivars and management practices, there is a need to modify the rates and timing of N application. The results suggest that N application levels could be increased by at least 50 kg N ha⁻¹ year⁻¹ from the current maximum accepted rate (250 kg N ha⁻¹ year⁻¹) without too high NO₃^- or CP concentrations in feed, or too high N balance that indicates increasing risk of N leaching.     

The productivity of oats and berseem clover intercrops. I. Primary growth characteristics and forage quality at four densities of oats

Berseem clover (Trifolium alexandrinum L.) was sown as an intercrop with oats (Avena sativa L.) at 0, 30, 60, 90 and 240 oats plants m^?2 in May in 1999 and 2000 in Alberta, Canada. Forage yield and quality were measured at 10‐d intervals between 35 and 88 d after planting (DAP). Yield is defined as the biomass above 6 cm of the soil surface. The dry‐matter (DM) yield of berseem clover in sole crops increased by 5–10 g m^?2 d^?1 between 35 and 55 DAP and then increased by 21–28 g m^?2 d^?1 between 55 and 75 DAP. The DM yields of oats sown at 240 plants m^?2 increased by 26–28 g m^?2 d^?1 over the whole period from 35 to 75 DAP. Oats were the dominant component in the intercrops, even at low densities of oats. Berseem clover grown with 60 oats plants m^?2 received only 0·24 of the incident light when shading by oats peaked at 65 DAP. DM yields of berseem clover in intercrops with 60 oats plants m^?2 averaged 0·14–0·32 of the yields of berseem clover sole crops. Between 35 and 88 DAP in 2000, the crude protein (CP) concentration of berseem clover sole crops declined linearly from 310 to 180 g kg^?1 DM, and the CP concentration of oats exhibited a quadratic response, declining from 350 g kg^?1 DM at tillering to 110 g kg^?1 DM at the soft dough stage. The mean CP concentration of berseem clover in intercrops with 60 oats plants m^?2 was 25 g kg^?1 less than in berseem clover sole crops, indicating that competition by oats reduced the CP concentration of berseem clover. At later sampling dates, CP and DM yields of intercrops with oats at 60 plants m^?2 equalled those with oats at 240 plants m^?2. The addition of berseem clover to oats in intercrops at 60 oats plants m^?2 reduced the neutral‐detergent fibre concentration by 30 g kg^?1 DM compared with oats alone. Oats were very competitive as a companion crop for berseem clover. Adding berseem clover to oats increased forage quality and may provide for increased intake and digestibility of forage to support higher livestock productivity.     

Sheep grazing and defoliation of contrasting varieties of organically grown winter wheat with and without undersowing

Field experiments in Gloucestershire, UK, in the 1990–91, 1991–92, 1993–94 and 1994–95 growing seasons explored the merits of grazing in spring a traditional tall wheat (Triticum aestivum) variety, Maris Widgeon, with more modern shorter varieties. In the first 2 years, defoliation was achieved by mowing at 7 cm in March and/or April. In the second 2 years, varieties sown at two sowing dates were grazed by sheep at a stocking rate of 42 × 50 kg sheep ha^?1 for 3 or 4 days in March. Defoliation reduced crop height and interception of photosynthetically active radiation (PAR). In 1991–92, mowing significantly reduced grain yield of some of the shorter varieties but not of Maris Widgeon. This interaction was related to the amount of PAR intercepted. In this year, mowing improved the establishment of undersown white clover (Trifolium repens) and perennial ryegrass (Lolium perenne), but in subsequent years the conditions were much drier and undersowing failed. In the last two experiments, grazing in March did not significantly reduce grain yield of any variety. The quality of the forage eaten by the sheep had a modified acid-detergent fibre (MADF) content of less than 300 g kg^?1 dry matter (DM) and a crude protein (CP) content of more than 200 g kg^?1 DM in both seasons. Yield of DM and calculated metabolizable energy (ME) of different varieties removed by the sheep interacted strongly with sowing date. September-sown Maris Widgeon provided ≈ 0·7 and 0·3 t DM ha^?1 (or 7·8 and 3·4 GJ ME ha^?1) in March 1994 and March 1995 respectively. However, the shorter wheat varieties, Hereward and Genesis, only provided 0·3 and 0·1 t DM ha^?1 when sown at the same time in the 2 years. At later sowing dates all of the varieties only provided about 0·1 t DM ha^?1 when sown in October 1993, or 0·01 t DM ha^?1 when sown in November 1994. Sheep grazing reduced total weed biomass in June, and reduced the emergence of weed seedlings from soil samples collected after the wheat harvest. Effects of defoliation on foliar infection by Septoria tritici were inconsistent.     

The effect of different additives on the fermentation quality, aerobic stability and in vitro digestibility of pea/wheat bi-crop silages containing contrasting pea to wheat ratios

Studies were conducted to compare the effects of using two microbial inoculants, a sulphite salt‐based additive, formic acid and quebracho tannins, on the fermentation quality, nutritive value and aerobic stability of pea/wheat bi‐crop silages. Spring peas (Pisum sativum var. Magnus) and spring wheat (Triticum aestivum var. Axona) were drilled together at rates that gave high (HP/W; 3:1) or low (LP/W; 1:3) pea to wheat ratios. The peas and wheat were harvested at the yellow wrinkled pods and late milk/early dough maturity stage, respectively, and conserved in 1·5‐kg polyethylene bag, laboratory silos. The bi‐crops were conserved without treatment (control) or treated with either of two lactic acid bacteria‐based inoculants [Lactobacillus buchneri; applied at 10⁵ colony‐forming units (CFU) g^–1 fresh weight (FW) or Lactobacillus plantarum (applied at 10⁶ CFU g^–1 FW)], sulphite salts (applied at the rate of 1 ml sulphite solution kg^–1 FW), quebracho tannins (applied at 16 g kg^–1 FW) and formic acid (applied at 2·5 g kg^–1 FW). Six replicates were made for each treatment, and the silos were opened after 112 days of ensilage. The level of peas in the bi‐crop influenced the effectiveness of the additives. With the exception of sulphite salts, all the additives significantly reduced the soluble nitrogen (N) and ammonia‐N concentrations of all the silages. The ratio of lactic acid to acetic acid was generally lower in the LP/W silages than in the HP/W silages, and the additive treatments only increased the in vitro digestible organic matter in dry matter of the LP/W silages. Of all the additives evaluated, formic acid resulted in the least aerobic spoilage in HP/W bi‐crop silages. However, in the LP/W bi‐crops, additive treatment was not necessary for ensuring aerobic stability.     

Potential of Cistus ladanifer L. (rockrose) in small ruminant diets – effect of season and plant age on chemical composition,in vitro digestibility and antioxidant activity

Shrubs can provide an important contribution to the fodder resources for small ruminants in Mediterranean areas, but there is limited information on their feed value, including secondary metabolites and their seasonal differences. This study evaluated the effect of seasonal variation in chemical composition, in vitro digestibility and antioxidant activity of the aerial parts of plants of Cistus ladanifer of two age groups [young plants vs. older ones (2–6 years old)]. Aerial parts of C. ladanifer plants of both age groups were characterized by moderate cell‐wall content [321–410 g NDF kg^?1 dry matter (DM)], high levels of phenolic compounds (55·1–106 g gallic acid equivalents per kg DM) and condensed tannins (CT) (32·1–161 g kg^?1 DM), low protein content (55–100 g kg^?1 DM) and low digestibility (249–315 g of digestible organic matter per kg DM). During autumn and winter, C. ladanifer showed higher protein levels and lower cell‐wall content than in the other seasons. The highest values of phenolic compounds, CT and antioxidant activity were achieved during summer. Young plants showed higher levels of phenolic compounds during spring, summer and winter, and higher CT contents in summer (more than 54 g kg^?1 DM) compared to old plants. Aerial parts of C. ladanifer of both age groups may be used as a component of ruminant nutrition, but only as a supplement and associated with other feeding resources to complement its nutritional imbalances.     

Seasonal nitrogen effects on nutritive value in binary mixtures of tall fescue and bermudagrass

The addition of cool‐season, tall fescue [Lolium arundinaceum (Schreb.) Darbysh.], to warm‐season, bermudagrass [Cynodon dactylon (L.) Pers.], pastures can improve forage productivity and nutritive value. Effects of four binary mixtures consisting of cv. Flecha (incompletely summer dormant) and cv. Jesup (summer active) tall fescue overseeded into established stands of cv. Russell and cv. Tifton 44 bermudagrass and three seasonal N treatments were evaluated on dry‐matter (DM) yield, crude protein (CP), in vitro true digestible DM (IVTDDM), acid detergent fibre (ADF) and neutral detergent fibre (NDF). Nitrogen‐timing treatments were 168 kg N ha^?1 (as ammonium nitrate) split into three applications per season with an additional 8·6 t ha^?1 of broiler litter (as‐is moisture basis) split into two applications varied to favour either tall fescue (in October and January), bermudagrass (in March and May) or both grasses (in January and March). Treatment effects were determined in samples of mixed herbage harvested in April, May, July, August and September of 2009 and 2010. Regardless of bermudagrass cultivar, herbage DM yield was greater (P < 0·05) in Flecha–bermudagrass than Jesup–bermudagrass in July of both years and in August 2010. Nutritive value generally was greatest in Jesup–Tifton 44, based on high CP and IVTDDM, and low ADF and NDF. Averaged across mixtures, avoiding fertilizer N and litter applications beyond April increased (P < 0·01) DM yield in April and May and IVTDDM in July (603 vs. 629 g kg^?1; 2‐year average) and August (618 vs. 660 g kg^?1) compared with applications in January–July. The timing of N and broiler litter applications on tall fescue–bermudagrass to favour growth of tall fescue appeared to increase fescue cover during the cool season and nutritive value of the mixed herbage during the warm season.