Regrowth Harvests Research Articles

Productivity nutritive value and economic potential of irrigated fodder in two regions of Ghana

AbstractAn on‐farm study was conducted in the northern and Upper East regions of Ghana to investigate the productivity and nutritive value of irrigated ruzi grass [Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins] (syn. Brachiaria ruziziensis (R. Germ. and C.M. Evrard)] and forage sorghum (Sorghum almum) grasses as options against dry season feed scarcity and to understand associated market opportunities. Sixty participating farmers each established 100‐m2 plots which were sown at 15 kg ha–1 drilled in 60‐cm rows in the dry season of 2016 and 2017. Irrigation was by flooding of soil surface every alternate day throughout the period of the trial. At both regions, herbage accumulation and nutritive value of forage species were determined at four harvesting stages: 4, 8, 12, and 16 weeks after planting (WAP) followed by 4‐wk intervals between harvests. At the end of the trial, fresh biomass was weighed, bundled, and sold in major livestock feed markets to estimate market price. Allowing forages to establish for only 8 wk resulted in two 4‐wk regrowth harvests with dry matter accumulation (DMA) ranging from 4.5 to 8.1 Mg DM ha–1 from both species and in both regions. Generally, herbage nutritive values in terms of crude protein, metabolizable energy (ME) concentration, and in vitro digestible organic matter (IVDOM) declined (P < .05) while DMA increased linearly with delay in harvest. While both grasses adapted well in the regions under irrigation, 8 WAP harvests provided the best balance between nutritive value and DMA. Irrigated fodder must be marketed more effectively since currently market prices are not closely related to nutritive value.

Evaluation of warm season annual forages for forage yield and quality in the north-central United States.

Grazing-based dairy operations require productive, high-quality forages capable of supporting the nutritional needs of mid-lactation dairy cows. Our objectives were to evaluate primary and regrowth harvests of two cultivars of sudangrass (SU), sorghum-sudangrass (S×SU), and pearl millet (PM) forages for growth and nutritive characteristics within the specific context of suitability for grazing by dairy cows. Three harvest cycles, including primary and regrowth cycles in 2016, and a single harvest cycle of primary growth in 2017, were evaluated at two locations (Prairie du Sac and Marshfield, WI). Within each cycle, sampling was initiated when canopy height was about 41 cm and continued thereafter on weekly intervals for 5 weeks, resulting in six equally spaced sampling dates per harvest cycle. Data were analyzed as a split-plot design with cultivars (6) as whole-plots arranged in randomized complete blocks and weekly harvest dates (6) as subplots. Yields of dry matter (DM) were less consistent at the more northern location (Marshfield), which is known for its heavier, poorly drained soils. Despite locational differences, the taller-growing cultivar within each forage type frequently exhibited yield advantages over dwarf or shorter-growing cultivars; this occurred for 7 of 9 intra-forage-type comparisons (P ≤ 0.021) across three harvest cycles at Prairie du Sac, and for 6 of 9 similar comparisons (P ≤ 0.032) at Marshfield. In 2016, shorter-growing cultivars had greater percentages of leaf in 4 of 6 intra-forage-type comparisons at both locations (P ≤ 0.004), which is especially relevant for grazing. Similarly, PM cultivars exhibited shorter canopy heights (P ≤ 0.002), but greater percentages of leaf (P < 0.001), than all other cultivars during all harvest cycles at both locations. However, the greater leaf percentages exhibited by PM cultivars did not translate into reduced percentages of structural plant fiber (asNDFom) on a whole-plant basis during any harvest cycle at either location; furthermore, asNDFom concentrations for PM cultivars were greater (P ≤ 0.047) than observed for other cultivars within 3 of 6 harvest cycles across both locations. Ruminal in-situ degradation of asNDFom for whole-plant forages based on a 48-h incubation was significantly greater (P ≤ 0.006) for PM compared with other cultivars in 4 of 6 harvest cycles. Pearl millet cultivars generally exhibited more suitable characteristics for grazing livestock than SU or S×SU cultivars.

Herbage Accumulation, Nutritive Value, and Regrowth Potential of Sunn Hemp at Different Harvest Regimens and Maturity

Low productivity and nutritive value of cool‐season perennial forages, such as tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] during summer necessitates the identification of warm‐season forages that improve nutritive value and yield of cool‐season‐based forage systems. A fast‐growing, warm‐season tropical legume sunn hemp (Crotalaria juncea L.) has the potential to accomplish this. Our objectives were to evaluate herbage accumulation and nutritive value (crude protein [CP], in vitro true digestibility [IVTD], neutral detergent fiber [NDF], acid detergent fiber [ADF], and NDF digestibility [NDFD, 48 h]) of sunn hemp harvested 35, 45, and 55 d after planting (DAP) at 10‐ and 15‐cm heights and to determine regrowth potential when harvested 20 d after each initial harvest over two consecutive years. Sunn hemp herbage accumulation averaged 1.9 and 3.1 Mg ha−1 at 45 and 55 DAP, respectively. Herbage accumulation of initial harvest increased linearly from 35 to 45 to 55 DAP by 119 and 57%, respectively. Herbage accumulation of regrowth after the 35 DAP initial harvest was 262 and 303% greater than the 45 and 55 DAP initial harvests, respectively. Cutting height did not affect (P &gt; 0.05) any variables. The greatest CP (154 g kg−1 dry matter) was observed at 35 DAP and decreased linearly with DAP. Both NDF (P &lt; 0.01) and ADF (P = 0.01) concentrations increased linearly with DAP for both initial and regrowth harvests. The IVTD of initial and regrowth harvests averaged 794 and 624 g kg−1 dry matter, respectively. Forage NDFD for initial and regrowth harvests averaged 487 and 392 g kg−1 NDF, respectively. Nutritive value and herbage accumulation of sunn hemp can be optimized by initially harvesting between 35 and 45 DAP, and leaving at least 10 cm of residue to allow for regrowth.

Sparse‐Flowering Orchardgrass is Stable Across Temperate North America

ABSTRACTOrchardgrass (Dactylis glomerata L.) is a major component of many pastures in temperate North America. Early and profuse flowering in pastures is problematic due to livestock refusal to consume flowering stems. The objective of this research was to determine the stability and agronomic impact of recently developed sparse‐flowering orchardgrass populations across temperate North America. Six cultivars, three sparse flowering and three normal flowering, were grown at 21 locations in temperate North America and evaluated for panicle density, heading date, and forage yield. Sparse‐flowering cultivars had 57% fewer panicles than normal‐flowering cultivars, but this effect was highly dependent on mean winter temperature, with normal‐flowering cultivars showing twice as much temperature sensitivity compared to sparse‐flowering cultivars. Forage yield of sparse‐flowering cultivars was reduced by approximately 24 to 32% for first harvest and 2 to 9% for regrowth harvests compared to normal‐flowering cultivars and this reduction in forage yield was independent of mean winter temperature. The forage yield reduction associated with sparse flowering is most likely due to a combination of physiological load (loss of stems) and opportunity cost (lack of selection pressure for yield), suggesting an opportunity to improve forage yield potential of this sparse‐flowering germplasm pool.

Yield and canopy characteristics of switchgrass (Panicum virgatum L.) as influenced by cutting management

Abstract Perennial warm season grasses, such as switchgrass (Panicum virgatum L.), complement cool-season species by filling the period of low biomass production called summer-slump. Although switchgrass is widespread in the Great Plains of the USA, there is very little information available about its management in mountain regions. A field experiment was conducted in Blacksburg, VA, USA, to determine the influence of dates of first and regrowth harvest, and cutting height on the canopy structure of the winter hardy cv. ‘Pathfinder’. The number, height and weight of tillers, yield distribution, light penetration through the canopy, leafiness, specific leaf area and leaf area index were investigated. Harvested biomass yield increased as date of first harvest was delayed throughout June and cutting height was reduced from 300 mm to 200 mm, but the yield of regrowth declined accordingly. This decline was caused by the removal of an increasing percentage of apical meristems and increasing damage to the crop canopy, in particular the loss of a greater proportion of photosynthetically active leaf area. A lower cutting height also reduced the amount of biomass produced in the following year. Cutting at 300 mm in early June can maximise the amount of high quality (defined as high concentrations of in vitro digestible dry matter and crude protein) biomass available for use as animal feed as compensation for cool season grasses during the first half of July.

Influence of season/year and species on chemical composition and in vitro digestibility of five Indigofera accessions

Two experiments were completed to determine the influence of season/year and species on forage quality of Indigofera accessions. In Experiment 1, leaf material was collected from five Indigofera species ( i.e., I. amorphoides, I. arrecta, I. brevicalyx, I. costata and I. cryptantha) by harvesting six middle plants of a plot in the autumn of 2003 and the autumn of 2004. In Experiment 2, edible forage (leaves + <3 mm stems) material were collected by harvesting six middle plants in the autumn of 2004 and the spring of 2004. Both leaf meal and edible forage material were analyzed for dry matter (DM), ash, crude protein (CP), neutral detergent fibre (NDF), in vitro digestible organic matter (IVDOM), as well as Ca, P, Mg, Cu, Zn and Mn concentrations. In Experiment 1, the interaction effects occurred between species and year of cutting (P<0.05) in studied parameters except Cu concentration. In Experiment 2, interactions (P<0.05) occurred between species and season effect for ash content as well as Ca and Mg concentrations in the edible material. The CP content of the leaf meal ranged between 223 and 311 g/kg DM and that of edible forage material between 81 and 287 g/kg DM. Spring growth had a higher (P<0.05) CP content than autumn growth in all species. The NDF content of leaves ranged between 189 g/kg DM in I. amorphoides and 504 g/kg DM in I. costata, and that in edible material ranged between 328 g/kg DM in I. arrecta and 654 g/kg DM in I. cryptantha. The in vitro OM digestibility of leaves ranged between 568 g/kg DM in I. cryptantha and 717 g/kg DM in I. amorphoides, while that of edible material ranged between 507 and 722 g/kg DM in I. cryptantha. In contrast to the trend with CP and NDF, in vitro OM digestibility of dry material tended to decrease from the spring of 2004 to the autumn of 2004 harvest. Higher levels of Ca, P, Mg, Zn and Cu occurred in the leaf meal of the first harvest than in the re-growth harvest. All of the species had Ca, Mg, Zn and Mn levels that could meet the requirements of ruminants, but P and Cu were slightly deficient for some of the species in the autumn harvest, making it essential to supplement P and Cu from other sources during this period to meet animal requirements.

Stockpiled Prairiegrass‐Brassica Hybrid Mixtures Tolerate Repeated Defoliation in Autumn

Stockpiling herbage helps redistribute nutrient availability and supplements quantity to sustain or finish livestock, depending on production objectives. In the Appalachian region of the USA, autumn stockpiled herbage is harvested, with little expectation for useable regrowth. spp. and prairiegrass (Vahl.) grow vigorously in autumn and tolerate defoliation providing a means to extend productivity in autumn. Mixed stands of prairiegrass and a brassica hybrid were established in late June of 2003 and 2004, with clipping begun in mid-September to determine production and nutritive value of regrowth herbage. Stockpiled prairiegrass-brassica hybrid stands tolerated repeated clipping, but stockpiled yield and the number of regrowth harvests decreased with increased duration of the stockpile interval, and no regrowth harvests were obtained when the stands were stockpiled until mid-November (130 days after planting). Regrowth accounted for as much as 35% of total yield in autumn when stockpiled harvests were made prior to late October (about 115 days after planting). Nutritive value expressed in terms of nonstructural carbohydrates, crude protein, and total digestible nutrients varied depending on year, but decreased with successive clippings or increased stockpiling duration. Herbage and nutrient yield of a prairiegrass-brassica hybrid mixed stand declined substantially after mid-October, in part, reflecting a shift in growth from leaf to tuber in the brassica component of the stand. Stockpiling stands of prairiegrass-brassica hybrid beyond mid-October essentially eliminates any meaningful regrowth production. Regrowth from stands clipped prior to mid-October extends the duration of growth of the mixture and makes a modest contribution to total herbage production in autumn.

Impact of Phosphorus from Dairy Manure and Commercial Fertilizer on Perennial Grass Forage Production

AbstractIncreased recovery and recycling of manure phosphorus (P) by crops on dairy farms is needed to minimize environmental problems. The main objective of this study was to compare P utilization by orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinaceae Schreb.) from dairy manure or inorganic fertilizer. The study was conducted from 1994 to 2000 at the Cornell University Baker Farm, Willsboro, NY, on a somewhat poorly drained Kingsbury clay (very–fine, illitic, mesic Aeric Epiaqualfs). The design was a split‐plot in a randomized complete block with two manure rates (16 800 and 33 600 kg ha−1) and one nitrogen (N) fertilizer rate (84 kg N ha−1 at spring greenup and 56 kg N ha−1 prior to each regrowth harvest) as the main plots and grass species as subplots replicated six times. Fertilizer P [Ca(H2PO4)2] was applied to the fertilizer treatment in 1995 and 1996 at 11 kg P ha−1 year−1. Orchardgrass P removal averaged 21 % higher than tall fescue P removal for the spring harvest, but orchardgrass averaged 24 % lower P removal than tall fescue removal for all regrowth harvests from 1995–99. Phosphorus herbage concentration in the fertilizer treatment was in the range of 1.9–2.7 g P kg−1 compared with 2.2–5.3 g P kg−1 in the manure treatments. Seasonal P removal ranged from as low as 9.2 kg P ha−1 to as high as 48.5 kg P ha−1. Morgan extractable soil P in the top 0–0.20 m remained high through 1999, with 29.1 kg P ha−1 at the highest manure rate in tall fescue compared with 8.4 kg P ha−1 measured in 1993 prior to the experiment. In 2000, soil P at the highest manure rate in tall fescue dropped to 10.1 kg P ha−1, following cessation of manure application in 1998. Intensively managed harvested orchardgrass and tall fescue have the potential to remove large quantities of manure P.

TETANY POTENTIAL OF ORCHARDGRASS AND TALL FESCUE AS INFLUENCED BY FERTILIZATION WITH DAIRY MANURE OR COMMERCIAL FERTILIZER

ABSTRACT The main objective of this study was to compare potassium (K), calcium (Ca), and magnesium (Mg) utilization and grass tetany potential of orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinaceae Schreb.) fertilized with dairy manure or commercial fertilizer. The study was conducted from 1994 through 2000 in Willsboro, NY on a Kingsbury clay soil (very-fine, illitic, mesic Aeric Ochraqualf) of somewhat poor drainage. The design was a split-plot in a randomized complete block with two manure rates (16.8 Mg ha−1 and 33.6 Mg ha−1) and one fertilizer treatment (84 kg N ha−1 at spring greenup and 56 kg N ha−1 prior each regrowth harvest) as the main plots and grass species as subplots replicated six times. Potassium concentration and uptake increased after two years of manure application compared to commercial fertilizer treatment and residual effects of manure were large at least three years following manure application. Calcium concentration and uptake decreased after two years of manure application compared to the commercial fertilizer treatment, but there were no differences in treatments three years after manure application had ceased. Magnesium concentration and uptake at the high manure rate did not differ from fertilizer treatment in all years. Orchardgrass was more grass tetany prone than tall fescue as a result of dairy manure application. The K/(Ca+Mg) ratio in plant tissue was as high as 3.26 for orchardgrass and as high as 2.11 for tall fescue for spring harvests at the highest manure rate. The K/(Ca+Mg) ratio in plant tissue was in the range of 0.34–1.74 (below the 2.20 critical level) for all three years with no manure application. Soil K increased in manure treatments from an initial 76.8 kg ha−1 (1993) to 171.7 kg ha−1 (1997) in the highest manure treatment. After three years of no manure applications, soil K had been reduced to the initial level.

Leaf and Stem Mass Characteristics of Cool‐Season Grasses Grown in the Canadian Parkland

Grasses adapted to both hay and pasture are lacking in the prairie parkland. ‘Regar’ meadow bromegrass (Bromus riparius Rhem.), ‘Manchar’ smooth bromegrass (B. inermis Leyss.), S9044 (a smooth–meadow bromegrass cross), common meadow foxtail (Alopercurus pratensis L.), and ‘Kay’ orchardgrass (Dactylis glomerata L.) were evaluated for traits useful in dual purpose grass species at early (late May), late (late June), and regrowth (early September) harvests. Herbage, leaf, and stem nutritive value; mass; and leaf/stem ratio were determined. Differences among species were related more to herbage mass and morphology than to leaf and stem quality. Early harvest orchardgrass herbage mass was low at 55% of meadow foxtail (2.9 Mg ha−1). However, stem content of meadow foxtail represented 60% of early herbage mass, limiting its potential. Regrowth mass of meadow bromegrass, S9044, and orchardgrass exceeded 2.5 Mg ha−1, whereas smooth bromegrass and meadow foxtail were as low as 2.1 Mg ha−1. Regrowth leaf mass of the former species exceeded 1.9 Mg ha−1. Late herbage mass of smooth bromegrass was always greater than the other species. Leaf acid detergent fiber (ADF) of S9044 and smooth bromegrass was lower (range 189–242 g kg−1) than meadow bromegrass (range 217–284 g kg−1). By contrast, late and regrowth harvest stem ADF of meadow bromegrass was lower (range 237–360 g kg−1) than S9044 (range 257–366 g kg−1). Variation among Bromus types for late and regrowth yield, and leaf fiber may influence management strategies.

Fodder production of some shrubs and trees under two harvest intervals in subhumid southern Ghana

The study was undertaken to determine the relative performance of 13 fodder trees and shrubs in herbage production and quality under two forage regrowth periods six and 12 weeks. In primary growth assessment it was found that the species which achieved the most height growth were Cajanus cajan, Sesbania sesban and Gliricidia sepium. In terms of herbage dry matter production the species which performed best were Cajanus cajan, Flemingia macrophylla, Calliandra calothrysus, Codariocalyx gyroidesand Gliricidia sepium. In crude protein content the superior species were Albizia lebbeck, Cajanus cajan, Leucaena leucocephala and Sesbania sesban. Regrowth harvests in the second year showed Gliricidia sepium, Calliandra calothrysus and Flemingia macrophylla achieve the greatest herbage yields with yields in excess of 1 t/ha obtaining at the first 12 week regrowth harvest. Albizia lebbeck, Cajanus cajan, Leucaena leucocephala and Samanean saman produced consistently very high crude protein levels (more than 20%) in the regrowth harvests. Calcium contents of herbage of all test species in the regrowth harvests were in excess of the critical minimum requirement of 0.44% for ruminant feeding.

Variation in Eastern Gamagrass Forage Yield with Environments, Harvests, and Nitrogen Rates

AbstractEnvironmental variation, and the interaction of environment with management practices, can significantly affect perennial forage yields. The objective of this research was to evaluate the importance of environmental main effects and the interaction between environments, N rates, and harvests on eastern gamagrass [Tripsacum dactyloides (L.) L.] forage yields. Established eastern gamagrass stands were fertilized with 0, 168, or 336 kg N ha−1, and harvested three times during the growing season for three consecutive years at two locations in northern Missouri. Year and the year × location interaction were significant environmental sources of variation affecting forage yields. The year main effect had the larger variance component and accounted for 9% of the total variation in forage yields. The harvest main effect and year × harvest interaction had the largest variance components, and together accounted for more than 67% of the total variation in forage yields. Most of the variation between harvests resulted from differences in first‐harvest yields, taken at the reproductive growth stage, compared with regrowth harvest yields which were at vegetative growth stages. Variation in precipitation amounts between harvests significantly influenced regrowth harvest yields, causing a significant year × harvest interaction. Forage yield responses to N rates also varied between years, causing a significant year × N rate interaction. Location was not an important source of variation in eastern gamagrass forage yield in this study, nor was there a significant interaction between N rates and harvests. Resultsuggest that supplemental irrigation and longer rest periods between harvests may help improve forage yields and distribution.

The effects of wilting of grass prior to ensiling on the response to bacterial inoculation. 1. Silage fermentation and nutrient utilization over three harvests

AbstractFour silages were prepared from perennial ryegrass swards at each of first (primary growth), second (first regrowth) and third (second regrowth) harvests during the 1993 growing season. At each harvest the four silages included two unwilted (without and with inoculant at 2·4 l/t) and two wilted (without and with inoculant at 24 l/t). The four silages within a single harvest, were offered as the total diet at maintenance levels to 12 wether sheep for 3 weeks to determine nutrient apparent digestibilities. They were also given to 12 lactating dairy coivs together with a concentrate supplement, in a three-period change-over study with experimental periods of 8-weeks duration, to examine dry matter (DM) apparent digestibility and utilization of nitrogen (N) and energy in the diets.Inoculation tended to improve silage fermentation with on average lower pH and ammonia-N/total-N across the three harvests, while wilting of grass prior to ensiling significantly increased silage pH fP &lt; 0·001) and ammonia-N/total-N (P &lt; 0·001). Neither inoculation nor wilting had any significant effect on mean nutrient apparent digestibilities, assessed through sheep, across the three harvests. However, at the second harvest inoculation significantly reduced apparent digestibilities of DM (P &lt; 0·001) and N (P &lt; 0·001). At this harvest, wilting also significantly decreased apparent digestibilities of DM (P&lt;0·05) and N (P &lt;0·01), but significantly increased apparent digestibilities of DM (P &lt; 0·05), energy (P &lt; 0·001) and N (F &lt; 0·05) at the third harvest. When the silages were offered as mixed diets to dairy cattle, neither inoculation nor wilting had significant effects on digestibilities of DM, N and energy at any of the three harvests, except for wilting which significantly decreased DM apparent digestibilities (P &lt; 0·05) at the second harvest. However, the mean apparent digestibilities of DM (P &lt; 0·01), N (P &lt; 0·05) and energy (P &lt; 0·01) across the three harvests were significantly lower following wilting, and N apparent digestibility (P &lt; 0·05) was significantly higher following inoculation. The calorimetric data indicated that inoculaton had no significant effects on either methane energy output or heat production. Wilting also had no significant effect on methane energy output, but significantly increased daily heat production (P&lt;0·05) at the first harvest. The efficiencies of metabolizable energy utilization for lactation (k1) were similar between the four silages at each of the first and second harvests, with the average being 0·50. The results of the present study indicated that inoculation tended to improve silage fermentation and significantly increased mean N apparent digestibility of mixed diets across the three harvests, while wilting significantly reduced mean DM, N and energy apparent digestibilities of mixed diets. Neither inoculation nor wilting had significant effects on Rvalue.

Delay of harvest effects on forage yield and regrowth in spring and winter cereal mixtures

Spring-planted mixtures of spring and winter cereals extend the grazing season and maximize dry matter yield if the initial defoliation is delayed until the milk stage of kernel development of the spring cereal component. However, fall regrowth may be less than spring-planted winter cereal monocrops. Research was conducted at Lacombe, Alberta to determine the effect of time of initial cut and winter cereal species on initial yield, regrowth yield and factors affecting regrowth (tiller density, water-soluble carbohydrate (WSC) and etiolated regrowth immediately post-cutting) of the winter cereal component of spring-seeded monocrops of fall rye (Secale cereale L.), winter triticale (× Triticosecale Wittmack) and winter wheat (Triticum aestivum L.) and in binary mixtures with spring barley (Hordeum vulgare L.). Treatments were planted in early May and harvested initially when the barley reached the boot (B), heads emerged (H), H + 2 wk, H + 4 wk and H + 6 wk stages. Three weeks after the initial cut a regrowth harvest was conducted. Initial yields of both mixtures and monocrops increased until approximately H + 4 wk and H + 6 wk respectively, with no differences due to species in the mixture. The effect of crop stage at initial harvest on regrowth was much larger than the species effect. Monocrop regrowth decreased almost linearly with delay of defoliation, while that of the mixture (winter and spring components combined) declined at a faster rate. Tiller density, WSC and etiolated regrowth also followed decreasing trends with time of initial cut in the monocrops and mixtures. These trends were due directly or indirectly to very low light intensities in the lower levels of the canopies of both cropping systems after H + 2 wk. Both initial and regrowth yields of the winter cereal component of mixtures involving rye and triticale were generally superior to those involving wheat. The ability of the winter cereal component to regrow in mixtures may be related to plant size and therefore ability to compete during initial growth. In general, the initial harvest of the mixture should occur no later than H + 2 wk of the spring cereal component in order to allow sufficient time for recovery of the winter cereal component after harvest. Otherwise, a spring-seeded winter cereal would be a better alternative for fall pasture. Key words: Delayed harvest, spring and winter cereals, forage yield, regrowth

Eastern Gamagrass Silage Fermentation Characteristics and Quality under Different Nitrogen Rates

Perennial grass silages are needed as alternatives to corn (Zea mays L.) silage on erosive cropland. Eastern gamagrass [Tripsacum dactyloides (L.) L.] may offer an alternative to corn for silage production, but it's fermentation characteristics and quality under different rates of N have not been evaluated. A 5-yr-old stand of «PMK-24' eastern gamagrass was treated in 1991 and 1992 with ammonium nitrate at 0, 100, and 200 Ib N/acre and harvested for silage. Corn was grown adjacent to the eastern gamagrass stand in 1992 for comparison. First harvest eastern gamagrass forage was ensiled at the seed development stage in 1991 and inflorescence emergence stage in 1992, and regrowth forage at the vegetative stage both years. Eastern gamagrass silage pH was not influenced by stage of maturity or N rates, and averaged 0.4 to 0.8 pH units greater than corn silage

Trace element composition of Atriplex grown with saline drainage water

In the western San Joaquin Valley, California, there has recently been emphasis on identifying suitable halophytes for irrigation with agricultural effluent and grown as crops using standard farming practices. Five perennial halophyte species belonging to the genus Atriplex (common name, saltbush) were established with fresh water, irrigated with saline drainage water, and mechanically harvested four times during the first 27 months of growth. Bale samples collected from three regrowth harvests were analysed for Selenium (Se), Boron (B), Sulfur (S), Iron (Fe), Zinc (Zn), Manganese (Mn) and Copper (Cu). The mean tissue concentrations for all species over regrowth harvests were 129 mg kg −1 dry weight for B and 0.6 mg kg −1 dry weight for Se. Tissue levels of B and S were above, and the remaining trace elements were below the maximum tolerable levels recommended for ruminants. All species showed trends of increased tissue B concentrations with cumulative age of plants. Over all the species the highest Se concentrations were measured in forage harvested 27 months after planting. The trace element composition of the harvested forage from this site does not appear to be a limiting factor when considering the use of Atriplex bales as a blend in animal feed rations.

Selection for increased forage yield in alfalfa at different NaCl levels

Alfalfa (Medicago sativa L.) forage yield may be reduced by moderate levels of salinity. Increasing forage yield in saline environments through plant breeding could partially ameliorate this problem. However, prior indirect selection either in cell culture, at germination, or during seedling growth has not resulted in agronomically relevant levels of salt tolerance. This study was conducted to determine whether mean forage yield of alfalfa grown in saline environments could be increased. To reduce the number of possible selection schemes, forage yield data for five harvests from ‘Sonora’ and its parental cultivar ‘African’ grown in a greenhouse and irrigated with 0, 30, 60, or 80 mM NaCl were used to simulate one cycle of selection at each NaCl environment. Greatest gains in forage yield were expected under non-saline conditions with decreased gains under saline conditions. Selection based on yield in regrowth harvests was also predicted to be more efficient than that based on seedling harvest. Experimental populations were developed from Sonora and African at each NaCl level using phenotypic selection for increased mean forage yield for harvests 3 to 5. After each of two cycles of selection, forage yield from selected, control (plants selected randomly under non-saline conditions), and parental populations was evaluated at 0, 30, 60, and 80 mM NaCl. Gains in forage yield were observed in African when the selection and evaluation environments were the same, but in Sonora this was observed only at 0 NaCl. Selection at 0 NaCl did not increase forage yield at 60 or 80 mM NaCl in either germplasm source. This suggests that selection for increased forage yield may be successful at low to moderate NaCl levels in germplasm with ample variation for yield when grown in saline environments, while selection for increased forage yield in non-saline conditions may be ineffective.

Forage Yield, Nonstructural Carbohydrate Levels, and Quality Trends of Caucasian Bluestem

AbstractInformation is limited on growth pattern and the effects of management on regrowth yield, quality, and total nonstructural carbohydrate (TNC) levels of Caucasian bluestem [Bothriochloa caucasica (Trin.) C.E. Hubb.] grown in the southern Corn Belt. Field studies on a Creldon silt loam soil (fine, mixed, mesic Mollic Fraguidalf) were conducted to determine trends of the above parameters under various primary growth harvests (one‐time harvests at 0, 14, 28, 42, and 56 d after 4 June) and summer and late‐season regrowth harvests (initial harvest on 18 June and 16 July, respectively, with regrowth harvests 14, 28, 42, 56, 70, and 84 d later). Yield increased linearly (104 and 55 kg ha−1 d−1, respectively) for primary growth and summer regrowth, while late‐season regrowth yield had a cubic trend (y = 201 − 11x + 2.3x2 − 0.02x3; x = days after initial harvest). In vitro dry matter digestibility declined linearly with time (2.9 g kg−1 d−1) in primary growth, but the rate of decline varied depending on length of delay for summer and late‐season regrowth (y = 548 − 4.0x + 0.26x2; y = 436 + 0.9x − 0.19x2, respectively). Crude protein declined quadratically under all treatments (y = 125 − 1.0x − 0.005x2; y = 137 − 3x + 0.001x2;y = 71.2 + 1x − 0.001x2, respectively, for primary growth and summer and late‐season regrowth). Neutral detergent fiber levels increased linearly for primary growth and late‐season regrowth (y = 668 + 1.9x;y = 662 + 1.1x, respectively), while summer regrowth response was quadratic (y = 637 + 2.7x − 0.002x2). Digestible dry matter yield increased throughout the season until it declined in late September. Total nonstructural carbohydrate levels were lower than previously found in native C4 grasses and may not be as important for survival in Caucasian bluestem. Our data indicate that a mid‐June defoliation, with further defoliation up to late summer, may optimize Caucasian bluestem's potential in livestock grazing systems.

Evaluation of Atriplex lentiformis (Torr.) S. Wats. and Atriplex nummularia Lindl. as irrigated forage crops

Atriplex shrubs have been recognized for their high productivity, tolerance to saline–sodic soils and production of quality forage material. The purpose of this study was to evaluate Atriplex lentiformis (Torr.) S. Wats. and Atriplex nummularia Lindl. as agronomic forage crops when irrigated with brackish water obtained from an artesian well seepage pond. Dry matter production and forage quality of aboveground biomass, plants clipped to a height of 15–20 cm and subsequent regrowth of clipped plants were determined over a 5-month period during the establishment year. Yields and nutritive quality of each species varied with harvest date and treatment and with phenological stage at time of harvest. Highest biomass yields of A. lentiformis and A. nummularia were estimated to be 14·7 and 12·3 tonnes/ha, respectively. Total yields produced from the sum of the two clipped and subsequent regrowth harvests, were less than the highest biomass yields obtained in each species. Increase in dry matter production in both species was associated with a corresponding increase in stem components. In all biomass and first clipped treatments, ash and protein contents decreased and neutral-detergent and acid-detergent fibre levels increased from first to last harvest dates. Calcium and phosphorus declined over the season in most harvest treatments. Even though high yields of A. lentiformis and A. nummularia are generally associated with lower quality forage material during the first year of growth, cultivation of these species as irrigated crops provides a valuable source of nutritive components as determined by previous treatment and time of harvest.

Forage Quality of Winterhardy Lovegrasses

Forage Quality of Winterhardy Lovegrasses