Effect of stage of maturity of whole-crop barley on intake and liveweight gain by dairy steers differing in initial live weight

The effect of maturity at harvest of whole-crop barley for ensiling on intake and liveweight gain of dairy steers differing in initial live weight (LW) was evaluated in an experiment over two years. Light (104–120 kg) and heavy (402–419 kg) dairy steers were fed diets containing predominantly whole-crop barley silage harvested at the milk stage [dry matter (DM) content of 284 g kg⁻¹ and neutral-detergent fibre (NDF) concentration of 526 g kg⁻¹ DM] or the dough stage of maturity (DM content of 328 g kg⁻¹ and NDF concentration of 445 g kg⁻¹ DM) and supplemented with up to 1 kg of concentrate. Dry matter intake (g kg⁻¹ LW) was higher for whole-crop barley harvested at the dough stage than at the milk stage of maturity and the difference was greater in heavy than in light steers ( P <  0·001). Liveweight gain was higher and feed conversion ratio was lower for dough-stage compared with milk-stage silage ( P  <   0·05) but there was no interaction with size of steer. Whole-crop barley harvested at the dough stage of maturity promoted higher liveweight gains in dairy steers compared with whole-crop barley harvested at the milk stage due to a higher DM intake.     

Apparent digestibility and nitrogen utilization of diets based on maize silage harvested at three stages of maturity and fed to steers

Advancing maize crop maturity is associated with changes in ear‐to‐stover ratio which may have consequences for the digestibility of the ensiled crop. The apparent digestibility and nitrogen retention of three diets (Early, Mid and Late) containing maize silages made from maize of advancing harvest date [dry matter (DM) contents of the maize silages were 273, 314 and 367 g kg^?1 for the silages in the Early, Mid and Late diets respectively], together with a protein supplement offered in sufficient quantities to make the diets isonitrogenous, were measured in six Holstein–Friesian steers in an incomplete Latin square design with four periods. Dry‐matter intake of maize silage tended to be least for the Early diet and greatest for the Medium diet (P = 0·182). Apparent digestibility of DM and organic matter did not differ between diets. Apparent digestibility of energy was lowest in the Late diet (P = 0·057) and the metabolizable energy concentrations of the three silages were calculated as 11·0, 11·1 and 10·6 MJ kg^?1 DM for the Early, Medium and Late diets respectively (P = 0·068). No differences were detected between diets in starch digestibility but the number of undamaged grains present in the faeces of animals fed the Late diet was significantly higher than with the Early and Mid diets (P = 0·006). The apparent digestibility of neutral‐detergent fibre of the diets reduced significantly as silage DM content increased (P = 0·012) with a similar trend for the apparent digestibility of acid‐detergent fibre (P = 0·078). Apparent digestibility of nitrogen (N) was similar for the Early and Mid diets, both being greater than the Late diet (P = 0·035). Nitrogen retention did not differ between diets. It was concluded that delaying harvest until the DM content is above 300 g kg^?1 can negatively affect the nutritive value of maize silage in the UK.     

Nutritive quality and energy yield of high oil,opaque-2 and waxy maize hybrids compared to normal maize hybrids

Grain yield, chemical composition, protein quality and digestible energy were measured for 18 maize varieties (opaque-2, high oil, waxy hybrids, normal hybrids) cultivated in Yugoslavia. Protein quality assessment was based on amino acid composition, and true protein digestibility, biological value, net protein utilization and utilizable protein as determined in nitrogen balance experiments with rats. The protein concentration in dry matter varied from 8.63–18.81% while the fat concentration varied from 4.45–16.13%. There were only minor differences in ash and crude fibre, while starch and sugar varied inversely to fat and protein concentration. Lysine levels were approximately 30% higher for the opaque-2 varieties compared with normal maize, while leucine levels were about 30% lower. Yields were extremely high for all varieties with the highest value being 10.3 tonnes/ha. Due to the high yields, protein production/ha was high in range of 822–977 kg. This resulted in high yields of amino acids/ha. Protein utilization was very high in the opaque-2 varieties, which had the highest lysine contents. The biological values were close to 80 in these varieties, whereas they were only 60–65 in the normal maize varieties.     

The effect of stage of perennial ryegrass maturity at harvesting, fermentation characteristics and concentrate supplementation, on the quality and intake of grass silage by beef cattle

Abstract Two experiments were carried out in consecutive years to examine the influence of cutting date and restricting fermentation by carboxylic acid treatment on the nutrient intake from grass silage by beef cattle. In year 1, four cutting dates during July and August after a primary growth harvest and, in year 2, five cutting dates of primary growth between mid‐May and early July were examined. Herbage was ensiled either untreated or treated with high levels of acid additive (‘Maxgrass’, mean 8·6 l t^?1). Ninety‐six (year 1) or forty‐eight (year 2) continental cross steers were used in partially balanced changeover design experiments with each silage type either unsupplemented or supplemented with 4·5 (year 1) or 5·5 (year 2) kg concentrates head^?1 d^?1. Silage digestibility declined significantly between initial and final harvest dates (P < 0·001), whereas silage dry‐matter (DM) and digestible energy (DE) intakes were significantly higher in the initial compared with final harvest dates in both years of the study (P < 0·01). Similarly, silage DM and DE intakes, and total DM intakes, of acid‐treated and unsupplemented silages were greater than those of untreated and concentrate supplemented silages, respectively (P < 0·001). The results indicate that earlier cutting dates, and addition of acid to herbage before ensiling, can increase silage DM intake by beef cattle.     

Microbial community dynamics and their contributions to organic acid production during the early stage of the ensiling of Napier grass (Pennisetum purpureum)

The study aimed to disclose the microbial community dynamics and their contributions to organic acid production during the ensiling of Napier grass. Napier grass was harvested at the vegetative growth phase and ensiled for 30 days. Three silos were opened after 1, 2, 3, 5, 7, 14, and 30 days of ensiling respectively. The intensive fermentation was observed during the initial stage of ensiling, indicated by lower pH (<4.0) on d 2 of ensiling. Lactic acid (LA) was the primary fermentation product, although acetic acid (AA) concentration rapidly increased and LA/AA concentration gradually decreased after 3 days of ensiling. The ethanol concentration was already 11.8 g/kg DM on d 1 of ensiling and then remained stable until the end of ensiling. Lactococcus was the predominant genus during the initial 2 days of ensiling, and then, it was gradually replaced by Lactobacillus. The increase in ammonia nitrogen and butyric acid concentration after 7 days of ensiling was attributed to the growth of Clostridia, which is favored by the high moisture concentration in the Napier grass. The natural ensiling of Napier grass displayed LA-type fermentation and was dominated by the fermentation of Lactobacillus and Lactococcus. Lactobacillus is mainly responsible for the LA production during the ensiling of Napier grass.     

Effect on yield and dry-matter distribution of the stay-green characteristic in cultivars of forage maize grown in England

To test whether or not the ‘stay‐green’ (SG) characteristic confers benefits in terms of crop yield or distribution of dry matter (DM) in selected forage maize cultivars, an experiment was conducted in 1998 and 1999 at two sites in England: Writtle College, Essex and the University of Leeds, West Yorkshire. Five SG and five conventional (C) cultivars of forage maize were grown in replicated field‐scale plots at each site in both years. One‐metre lengths of single rows in each plot were harvested by hand, leaving a 20‐cm stubble, on four occasions each year over 3‐week periods (harvest 1 to harvest 4), prior to the harvest of the remainder of the fields. Plants were chopped, mixed and a subsample taken for determination of DM content by oven‐drying. Mean yields of whole plant DM were similar between SG and C cultivars. Both yield of DM and proportion of ear in the total plant DM increased from harvest 1 to harvest 4 (P < 0·01). The increase in DM yield between harvest 1 and harvest 4 was greater for C than for SG cultivars (P < 0·05). Within sites there were no differences in the concentration of whole plant DM between SG and C cultivars, which increased from harvest 1 to harvest 4 (P < 0·001). The proportion of ear DM in the whole plant DM tended to be higher for C than for SG cultivars in both years and increased (P < 0·001) from harvest 1 to harvest 4. The concentration of DM in the ear fraction was higher (P < 0·05) for C than for SG cultivars. We conclude that differences between SG and C cultivars of forage maize are likely to be relatively small when grown in the English climate and harvested after the same growing period.     

The effects of lactic acid bacteria on the fermentation,aerobic stability and nutritive value of maize silage

Maize was harvested at one‐third milk line (297 g kg^?1 DM) stage. All inoculants were applied at 1 × 10⁶ cfu g^?1 of fresh forage. After treatment, the chopped forages were ensiled in 1·5‐L anaerobic jars. Three jars per treatment were sampled on days 2, 4, 7, 12 and 90 after ensiling, for chemical and microbiological analysis. Homofermentative LAB‐inoculated silages had lower pH and higher lactate:acetate ratio (except for Lactobacillus plantarum/Pediococcus cerevisiae and L. plantarum/Propionibacterium acidipropionici) than the control and both heterofermentative LAB‐inoculated silages. Both L. buchneri inhibited yeast growth and CO₂ production during exposure of silage to air. The L. plantarum/P. cerevisiae, L. plantarum (Ecosyl) and L. plantarum/Enterococcus faecium‐inoculated silages had higher dry‐matter digestibility than the control and L. buchneri‐inoculated silages. Inoculants did not affect digestibility of neutral detergent fibre, except for L. buchneri (Biotal), organic matter nor ME content of silages. The LAB silage inoculants generally had a positive effect on maize silage characteristics in terms of lower pH and shifting fermentation toward lactate with homofermentative LAB or toward acetate with L. buchneri. The use of L. buchneri can improve the aerobic stability of maize silages by the inhibition of yeast activity.     

Yield,quality and ensilage characteristics of whole‐crop maize and of the cob and stover components: harvest date and hybrid effects

The objective of the study was to determine the effects of maize hybrid and harvest date on the yield, quality and subsequent conservation characteristics of whole‐crop, cob and stover silages. The experiment had a split‐plot design, with three main plots (date of harvest) and six subplots (hybrid) in each of three replicate blocks. Four maize hybrids (Tassilo, Beethoven, Andante and Nescio) were conventional hybrids used in commercial livestock production in Ireland, and two were categorized as high‐biomass hybrids (Atletico and KXA 7211). The three harvest dates – 16 September, 7 October and 28 October – represented early, normal and late harvests respectively. Averaged across hybrids, harvesting on 16 September reduced the DM yield (P < 0·05) and starch concentration (P < 0·01) of whole‐crop and cob, and decreased the neutral detergent fibre (P < 0·05) and acid detergent fibre (P < 0·01) contents of stover. Later harvesting date generally resulted in a more restricted, heterolactic fermentation that was associated with increased dry‐matter (DM) content at ensiling. Whole‐crop and stover from Atletico and KXA 7211 generally had higher DM yields (P < 0·05) and a more extensive fermentation compared to Tassilo, Andante and Nescio. Despite the high‐biomass hybrids having a higher DM yield than conventional hybrids, the high‐biomass hybrids had a lower (P < 0·05) content of cob and a corresponding higher (P < 0·05) content of stover. The changes in proportions of cob and stover in whole‐crop maize with later harvesting significantly influenced its silage digestibility and conservation characteristics.     

Effect of sowing ratio and stage of maturity at harvest on yield, persistency and chemical composition of fresh and ensiled red clover/lucerne bi-crops

Two experiments investigated (1) the effect of stage of maturity at harvest in the first year on yield and persistency of red clover and lucerne when grown as monocultures and bi‐crops, and (2) the effect of ensiling differing ratios of red clover and lucerne on forage quality and degree of proteolysis. Red clover (cv. Milvus) and lucerne (cv. Vertus) were established in triplicate plots at five sowing ratios:1·00 red clover, 0·75 red clover:0·25 lucerne, 0·50 red clover:0·50 lucerne, 0·25 red clover:0·75 lucerne and 1·00 lucerne. In year 1, plots were harvested in three strips, at different stages of plant maturity, either 11 (early), 13 (mid) or 15 (late) weeks after sowing. In years 2 and 3, the whole plot was harvested at each of four harvests taken during the growing season. The DM yield of lucerne in years 2 and 3 was higher than that of red clover, leading to increased yields from bi‐crops with increasing proportions of lucerne. Strips harvested at the mid‐stage of maturity in the first year on the 0·25 red clover:0·75 lucerne plots produced the highest DM yields overall. Ensiling red clover and lucerne bi‐crops was found to combine the improved wilting properties of lucerne and the reduced proteolysis of ensiled red clover.     

The nitrogen response of potato (Solanum tuberosum L.) in the field: nitrogen uptake and yield, harvest index and nitrogen concentration

Summary The response of potato to different rates of nitrogen supply ranging from 0–40 g m⁻² N was studied in five field experiments near Wageningen. NL (52⁰ North). In total two late potato cultivars and two sites were used during successive seasons. The results are summarized in a set of regression equations separately for total crop and tubers. The relation between nitrogen taken up (g m⁻²) in the total crop and total dry matter production (g m⁻²) could be described with the exponential equation: 1942–1900 * 0.93^X (r²=0.953, n=62). Nitrogen concentrations in the dry matter increased linearly with nitrogen uptake. Harvest indices for dry matter and nitrogen tended to decline with increase in N uptake. Cultivars differed only in the effect on N on tuber dry matter concentration. The relation between nitrogen uptake and nitrogen supply could be fitted with quadratic regression models. but coefficients were influenced by site and season.     

Effects of different rates and timing of application of nitrogen as slurry and mineral fertilizer on yield of herbage and nitrate-leaching potential of a maize/Italian ryegrass cropping system in north-west Portugal

Efficient use of cattle-slurry to avoid nitrogen (N) leaching and other losses is important in designing intensive dairy systems to minimize pollution of air and water. The response in dry-matter (DM) yield of herbage and nitrate-leaching potential to different rates and timing of application of N as cattle slurry and/or mineral fertilizer in a double-cropping system producing maize ( Zea mays L.) silage and Italian ryegrass ( Lolium multiflorum Lam.) was investigated in north-west Portugal. Nine treatments with different rates and combinations of cattle slurry, and with or without mineral-N fertilizer, applied at sowing and as a top-dressing to both crops, were tested and measurements were made of DM yield of herbage, N concentration of herbage, uptake of N by herbage and amounts of residual soil nitrate-N to a depth of 1 m, in a 3-year experiment. Regression analysis showed that the application of 150 and 100 kg of available N ha⁻¹ to maize and Italian ryegrass, respectively, resulted in 0·95 of maximum DM yields of herbage and 0·90 of maximum N uptake by herbage. Residual amounts of nitrate-N in soil after maize ranged from 48 to 278 kg N ha⁻¹ with an exponential increase in response to the amount of N applied; there were higher values of nitrate-leaching potential when mineral-N fertilizer was applied. The results suggest that it is possible in highly productive maize/Italian ryegrass systems to obtain high DM yields of herbage for maize silage and Italian ryegrass herbage with minimal leaching losses by using slurry exclusively at annual rates of up to 250 kg available N ha⁻¹ (equivalent to 480 kg total N ha⁻¹) in three applications.     

我国三熟制早熟油菜品种产量构成特点及育种对策

为提高三熟制地区油菜育种效率,本文研究了三熟制地区不同熟性油菜农艺性状对产量的影响。以2016-2020国家冬油菜品种区试中衡阳和宜春地区试验结果为基础数据,利用相关分析及通径分析研究了两个区域的油菜品种产量构成特点。结果发现,中熟组和早熟组株高、有效分枝数、菌核病发病率、病情指数、单株有效角果数、每角粒数、千粒重、密度、全生育期、含油量及产量差异显著。中熟油菜每角粒数、密度、菌核病抗性与产量呈极显著正相关,菌核病发病率、病情指数、生育期与产量极显著负相关,密度对产量的直接影响最大。早熟油菜株高、有效分枝数、单株有效角果数、每角粒数、密度、含油量与产量极显著正相关,菌核病发病率与产量显著负相关;对产量直接影响最大的是有效分枝数。认为育种策略中,两种油菜都应选育抗菌核病和适合高密度种植的品种,中熟油菜应提高单株有效角果数,而早熟油菜要增加有效分枝数。     

The effect of ensiling and fractionation on the suitability for combustion of three common grassland species at sequential harvest dates

In a Green Biorefinery processing green biomass, one possible application for the press‐cake fraction is as biomass fuel for combustion. In an industrial setting, the preservation of herbage as silage and its subsequent fractionation into press‐juice and press‐cake fractions represent the two major process steps in the utilization of green biomass. This study investigated (i) the effects of ensiling and fractionation on the chemical composition of three common temperate grassland species harvested at different stages of maturity and (ii) the suitability of the herbage of these species for thermal combustion. The high contents of ash, N, Cl and K in perennial ryegrass, cocksfoot and red clover, at both pre‐ and post‐ensiling, make these materials less suitable for combustion in certain applications. The loss of soluble/fermentable organic matter during ensiling increased the relative proportions of fibre, ash and N in the herbage, but these changes were relatively minor. In contrast, the substantial reduction in the concentration of compounds such as ash, N, Cl and K during fractionation improved the suitability of the press‐cake fraction for combustion compared with the parent material. Press‐cake prepared from later‐harvested grass herbage with lower ash, S and N contents would be more suitable for combustion.     

Performance and environmental effects of forage production on sandy soils. IV. Impact of slurry application, mineral N fertilizer and grass understorey on yield and nitrogen surplus of maize for silage

A field experiment was conducted from 1998 to 2001 to measure the performance and environmental effects of a maize crop (Zea mais L.) in a continuous production system with and without a grass understorey (Lolium perenne L.), with varied N inputs. The experiment was located on a sandy soil in northern Germany and comprised all combinations of slurry application rate (0, 20, 40 m³ ha^?1) and mineral N fertilizer (0, 50, 100, 150 kg N ha^?1). Understorey treatments included maize with and without perennial ryegrass. Net energy (NEL) yield of maize increased with mineral N application rate but reached a plateau at high rates. Increase in yield of dry matter because of mineral N fertilizer was lower with increased slurry application rate. Neither slurry and mineral N application nor a grass understorey affected NEL concentration of maize, whereas crude protein (CP) concentration increased with increase in application of slurry and mineral N fertilizer. Nitrogen supply by slurry or mineral fertilizer had no effect on the amount of N in the grass understorey after the harvest of maize. The average amount of N bound annually in the understorey was 60 kg N ha^?1. The reduced biomass of the understorey because of enhanced maize competition was compensated for by an increased CP concentration in the grass. The grass understorey affected the NEL yield of maize negatively only at very low levels of N input but increased the N surplus at all levels.     

Effect of replacing time available for grazing with time available for eating maize silage and soyabean meal on milk yield and feeding behaviour in dairy cows

Low rates of herbage dry matter (DM) intake impose limits on total daily DM intake in grazing dairy cows. The objective of this study was to increase total daily DM intake and milk production by restricting daily time available for grazing (TAG) and replacing it with time available for eating a maize silage/soyabean meal (TAMS) diet indoors. The treatments (TAG + TAMS) were 20 + 0, 19 + 1, 10 + 10 and 5 + 15 h. Measurements were made of milk production, intake and feeding behaviour. The interactions of TAG + TAMS treatments with sward height (SH) and concentrate level (CL) were also examined. Two experiments, each lasting 42 days, were carried out in spring ( Experiment 1 ) and autumn ( Experiment 2 ) using forty‐eight and twenty‐four Holstein‐Friesian cows respectively. Treatments were arranged in a factorial design with TAG + TAMS treatments, SH ( Experiment 1 only) and CL as the independent variables and a TAG + TAMS of 20 h. Reducing TAG and increasing TAMS significantly reduced estimated herbage DM intake and significantly increased maize silage/soyabean meal intake in both experiments, but there were no significant main effects of TAG + TAMS treatments on milk yield (mean, 27·4 and 25·5 kg d^?1 for Experiments 1 and 2 respectively), and yield of milk constituents. Increasing SH ( Experiment 1 ) and CL ( Experiments 1 and 2 ) significantly increased milk yield. In Experiment 1 , there was a significant interaction between TAG + TAMS treatments and SH with the taller sward height of 8–10 cm and the 20 + 0 treatment having the highest milk yield (29·7 kg d^?1) and the 5 + 15 treatment the lowest (27·2 kg d^?1), whereas at the lower sward height of 4–6 cm, milk yield was lowest on the 20 + 0 treatment (25·5 kg d^?1) with the other three treatments being higher (mean, 26·9 kg d^?1). Replacing TAG with TAMS significantly increased liveweight gain in Experiment 1 but not in Experiment 2 . Estimated rates of intake of herbage were lower in the autumn experiment ( Experiment 2 , 9·6 g DM min ^?1) than in the spring experiment ( Experiment 1 , 29·4 g DM min ^?1) but rates of intake of maize silage were higher in the autumn (112·4 g DM min^?1) than in the spring (72·5 g DM min^?1). In conclusion, in spring the response to replacing TAG with TAMS was dependent on sward conditions with the highest milk fat plus protein yield being on the 20 + 0 treatment at the high sward height and on the 19 + 1 treatment at the low sward height. The high liveweight gain of the 5 + 15 treatment could be an important means of restoring body condition in grazing lactating cows. In autumn, intakes of herbage were low in spite of its high estimated nutritive value with all treatments having a similar level of performance.     

The effect of harvest date and inoculation on the yield, fermentation characteristics and feeding value of kale silage

Using new harvesting and ensiling technologies, it is now possible to ensile kale ( Brassica oleracea ) successfully. However, there is little information available regarding the optimum time for harvest. The aim of this 2-year study was to compare the yield, fermentation characteristics and feeding value of kale harvested at different stages of growth, and ensiled with and without a bacterial inoculant. During Year 1 the crop was harvested after 15, 18 and 20 weeks of growth. The yield at each harvest was similar, but as the crop matured the crude protein (CP) concentration and buffering capacity decreased significantly, and there was a marked increase in the water-soluble carbohydrate (WSC) concentration. During Year 2 the crop was harvested at 14 and 17 weeks of growth. Again, the stage of maturity did not affect yield and, on this occasion, the chemical composition of the crop was unaffected by harvest date. However, the WSC and CP concentrations of the crop were lower in Year 2 than in Year 1, possibly as a result of differences in fertilizer regime. Each of the silages produced in Year 2 was offered to six Suffolk cross wether lambs, aged 10 months, to measure voluntary intake, in vivo digestibility and nitrogen retention. Neither harvesting date nor the use of an inoculant affected voluntary intake or nitrogen retention by the lambs. However, in vivo digestibility was higher in the kale silage harvested after 14 weeks of growth and when an inoculant was applied. The results obtained suggest that harvesting kale after 14 weeks of growth can produce highly digestible silage with a high CP concentration. Although delaying harvest until 18 weeks of growth will probably result in a decrease in the CP concentration of the crop, it should also lead to an increase in the WSC concentration of the crop, ensuring a more reliable fermentation.     

Effect of acetic acid,caproic acid and tryptamine on voluntary intake of grass silage by growing cattle

The objective of this study was to identify and quantify fermentation end‐products, detected with chromatographic techniques, that were negatively related to intake of grass silage by cattle. Further, the aim was to verify the intake‐depressing effect of these compounds in a feeding trial. A set of twenty‐four silages that had been used in a previous study to model variations in intake owing to fermentation quality was reanalysed with liquid and gas chromatography. Known and unknown chromatogram peaks were subjected to a regression analysis to determine which were negatively related to intake. Compounds were identified and quantified using a liquid chromatography–mass spectrometry system; acetic acid (AcA), caproic acid and tryptamine were chosen for verification. Growing steers were offered wilted silage with these three compounds added, separately or as a mixture, in proportions similar to the maximum values detected in the silages of the previous study. Dietary addition of AcA, either separately or mixed with the other two compounds, reduced silage dry matter (DM) intake. However, the reduction in silage DM intake equalled the amount provided by the added substances, so that no differences in total DM intake were observed for any of the dietary treatments.     

Effects of plastic mulch, sowing date and cultivar on the yield and maturity of forage maize grown under marginal climatic conditions in Northern Ireland

The effects of growing forage maize (Zea mays) with or without plastic mulching treatments on the dry‐matter (DM) yield, cob yield, DM content and starch content was investigated in Northern Ireland in 1996 and 1997. Cultivars differing in maturity characteristics were sown in spring at a range of dates in three replicated plot experiments and were used to compare the effects of two plastic mulches and an untreated control: one plastic mulch completely covered the rows (floating); the other had holes punched in the plastic, through which the plants grew (punch). Between April and October in 1996 and 1997, the Ontario heat units (OU) received were above average at 2489 and 2660 respectively; in those years without plastic mulches, the earliest maturing cultivar, Melody, yielded 11·0 and 13·6 t DM ha^–1, with dry‐matter contents of 214 and 215 g kg^–1 respectively. Mean daily increases in soil and air temperature under plastic mulches of up to 6°C and 11°C, respectively, were closely related to solar radiation. Under plastic mulches, 15% fewer OU were required to reach silking, and 33% more OU were available between silking and harvest. Meaned over three experiments, two years and three cultivars, plastic mulches, when compared with the unmulched control, increased maize yield from 12·0 to 14·7 t DM ha^–1, cob yield from 3·7 to 6·8 t DM ha^–1, dry‐matter content from 230 to 270 g kg^–1 and starch content from 198 to 272 g kg^–1. The effect of plastic mulch on the maturation of the crop was greatest at earlier sowings. In 1997, plants from an early sowing date (10 April) that had recently emerged through the punch plastic mulch were damaged by frost, whereas those in the floating plastic mulch plots were unaffected. When the floating plastic mulch was left on after the six‐ to eight‐leaf stage of the first‐early maize cultivar Hudson, the plants were physically damaged and the yield reduced, but DM and starch contents continued to increase. The increases in yield and dry‐matter content under the plastic mulch were greater in Diamant (second‐early cultivar) than in Melody (first‐early cultivar). It was concluded that, under marginal climatic conditions, plastic mulches ought to be used to improve the reliability of early cultivars rather than growing later maturing cultivars.     

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

In 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.     

The effect of harvest date and inoculation on the yield, fermentation characteristics and feeding value of forage pea and field bean silages

Two experiments describe the ensiling potential of whole‐crop forage peas (Pisum sativum) and field beans (Vicia faba). In Experiment 1, forage peas (cv. Magnus) and field beans (cv. Mayo) were harvested at 10, 12 and 14 weeks after sowing, and ensiled in 10 kg mini‐silos either untreated or treated with an inoculant (Lactobacillus plantarum). In terms of yield and ensiling potential, the optimum growth stage for harvesting forage peas occurred at 12 weeks of growth. In contrast, delaying the harvest of field beans until 14 weeks gave the highest yields of dry matter (DM) and crude protein (CP). Changes in crop maturity had little effect on the chemical composition of the fresh forages, but between‐harvest date differences were observed in the DM, ammonia‐N, CP, water‐soluble carbohydrates (WSC), acid‐detergent fibre (ADF), neutral‐detergent fibre (NDF), lactic acid and volatile fatty acids (VFA) concentrations and pH of the corresponding silages. Fermentation was improved by applying an inoculant. In Experiment 2, forage peas and field beans were harvested at 14 weeks after sowing and ensiled as round‐bale silage, either untreated or treated with an inoculant. The yields of the crops were similar, and the only difference in the chemical composition of the wilted forages was a higher CP concentration in the field beans. However, after the ensiling process was complete, the forage pea silages were found to have significantly higher DM, WSC, starch and butyric acid concentrations compared with the field bean silages, and lower ammonia‐N, CP, ADF, acetic acid and lactic acid concentrations. Inoculation was found to increase the lactic acid concentration and reduce the pH and ammonia‐N and acetic acid concentrations of the silages. Each of the silages produced in Experiment 2 was offered to six Suffolk crossbred wether lambs, aged 10 months. Voluntary DM intakes were similar on all treatments, despite the apparent digestibility of the forage pea silages being significantly higher than that of the field bean silages. Nitrogen retention was higher for lambs offered forage pea silage. Application of an inoculant was found to have a negative effect on the amount of N retained, indicating the necessity for more detailed investigations into proteolytic activity within these crops during the fermentation process.