In Vitro Organic Matter Disappearance Research Articles

Biological N2 Fixation, Belowground Responses, and Forage Potential of Rhizoma Peanut Cultivars

Grasslands in warm‐climate regions are often based on grass monocultures, increasing their dependence on N fertilizers. Integrating perennial legumes into grass pastures is a logical option. The objective of this 2‐yr study was to assess seven rhizoma peanut (Arachis glabrata Benth) cultivars: Arbrook, Arblick, Ecoturf, Florigraze, Latitude 34, UF Peace, and UF Tito. Above‐ and belowground responses included biomass, in vitro organic matter disappearance (IVOMD), N concentration, N content, δ15N, proportion of N derived from atmosphere (%Ndfa), and biological N2 fixation (BNF). Arbrook was more productive than Florigraze in both years (P ≤ 0.05) but produced similar biomass to other varieties in 2014. In 2015, Arbrook also was more productive than Arblick and Latitude 34. Herbage N concentration ranged from 19.2 to 36.3 g kg−1. Arbrook tended to be less digestible than other rhizoma peanut cultivars. The BNF represented >80% of herbage N and averaged 200 kg N ha−1 yr−1, with values ranging from 123 to 280 kg N ha−1 yr−1. Root and rhizome biomass varied among cultivars, with Ecoturf (26.9 Mg organic matter [OM] ha−1) and Latitude 34 (27.8 Mg OM ha−1) presenting greater root and rhizome mass than Florigraze (10.5 Mg OM ha−1) but similar to other varieties. Roots and rhizomes represented a significant portion of the total biomass and N pool, and further studies are needed to assess turnover of these tissues as well as their N contribution in grazing systems using grass–rhizoma peanut mixtures.

Effects of calcium oxide treatment at varying moisture concentrations on the chemical composition, insitu degradability, invitro digestibility and gas production kinetics of anaerobically stored corn stover.

The objective of this study was to determine the optimum conditions for calcium oxide (CaO) treatment of anaerobically stored corn stover by insitu and invitro methods. Four ruminally cannulated, non-lactating, non-pregnant Holstein cows were used to determine the insitu effective degradabilities of dry matter (ISDMD), organic matter (ISOMD), neutral detergent fibre (ISNDFD), invitro organic matter disappearance (IVOMD) and gas production in 72h (GP72h ) of corn stover. A completely randomized design involving a 3×3 factorial arrangement was adopted. Ground corn stover was treated with different levels of CaO (3%, 5% and 7% of dry stover) at varying moisture contents (40%, 50% and 60%) and stored under anaerobic conditions for 15days before analysis. Compared with untreated corn stover, the CaO-treated stover had increased ash and calcium (Ca) contents but decreased aNDF and OM contents. The moisture content, CaO level and their interaction affected (p<0.01) the content of aNDF, ash and OM, and the ratio of aNDF/OM. The greatest ISDMD, ISOMD and ISNDFD were observed when stover was treated with 7% CaO and 60% moisture, while no differences (p>0.01) in these insitu degradability parameters were observed between the stover treated with 5% CaO at 60% moisture content and those treated with 7% CaO at 60% moisture content. Corn stover treated with 5% CaO at 50% moisture had the maximum IVOMD and GP72h among the treatments, and there was no difference (p>0.01) between 50% and 60% moisture. Results from this study suggested that 5% CaO applied at 60% moisture could be an effective and economical treatment combination.

The influence of pomegranate-peel extracts on in vitro gas production kinetics of rumen inoculum of sheep

Different levels of pomegranate peel extracted by either water (PEH) or solvent mixture (PEM) were evaluated for their effect on in vitro gas production and ruminal fermentation patterns. Two levels of PEH or PEM (15 and 30 mg total phenolics (TP)/g DM of basal diet) were compared to a control (0) level. Ruminal fermentation parameters such as 24-h partitioning factor (PF24), gas yield (GY24), in vitro organic matter disappearance (IVOMD), metabolizable energy (ME), and microbial protein (MP) were calculated. The addition of PEH or PEM had no effect (P > 0.05) on asymptotic gas production, apparent degraded substrate (ADS), IVOMD, ME, PF24, GY24, MP, or total volatile fatty acids (VFAs). However, fermentation rate (P = 0.032) and the proportion of butyrate (P < 0.0001) decreased. The addition of either PEH or PEM with substrate resulted in lower acetate concentration (P = 0.002) and acetate to propionate ratio (P = 0.007) in comparison to the control. Inclusion of PEH or PEM led to a lower ammonia (NH3-N) concentration (P = 0.0002) and protozoa counts in comparison to the control. In conclusion, the addition of PEH or PEM positively modified some rumen parameters such as acetate to propionate ratio, NH3-N concentration, and protozoa population.

The influence of pomegranate-peel extracts on in vitro gas production kinetics of rumen inoculum of sheep

Different levels of pomegranate peel extracted by either water (PEH) or solvent mixture (PEM) were evaluated for their effect on in vitro gas production and ruminal fermentation patterns. Two levels of PEH or PEM (15 and 30 mg total phenolics (TP)/g DM of basal diet) were compared to a control (0) level. Ruminal fermentation parameters such as 24-h partitioning factor (PF_{24}), gas yield (GY_{24}), in vitro organic matter disappearance (IVOMD), metabolizable energy (ME), and microbial protein (MP) were calculated. The addition of PEH or PEM had no effect (P > 0.05) on asymptotic gas production, apparent degraded substrate (ADS), IVOMD, ME, PF_{24}, GY_{24}, MP, or total volatile fatty acids (VFAs). However, fermentation rate (P = 0.032) and the proportion of butyrate (P < 0.0001) decreased. The addition of either PEH or PEM with substrate resulted in lower acetate concentration (P = 0.002) and acetate to propionate ratio (P = 0.007) in comparison to the control. Inclusion of PEH or PEM led to a lower ammonia (NH_3-N) concentration (P = 0.0002) and protozoa counts in comparison to the control. In conclusion, the addition of PEH or PEM positively modified some rumen parameters such as acetate to propionate ratio, NH_3-N concentration, and protozoa population.

In vitro organic matter disappearance of tanniferous browse using rumen liquid from goats ingesting grass versus browse

In vitro organic matter disappearance (IVOMD) of African browse species often indicates artificially low nutritive value due to the presence of condensed tannins (CT). Diet of the rumen liquor donor may change this if it contains CT. Leaves from 11 browse species were evaluated for their IVOMD of nitrogen, fibre fractions and CT concentrations. Crude protein (CP) ranged from 14% to 25%, whereas neutral detergent fibre (NDF) varied from 20% to 40%. The CT fractions differed (P ≤ 0.05) among the browse species with most CT either soluble or bound to protein. Acacia brevispica and Berchemia discolor had the greatest concentrations of total CT, whereas Balanites aegyptiaca and Prosopis juliflora had the least. Rumen liquid from goats on grass diet (no CT) or browsing species with CT resulted in differences in IVOMD of NDF (P ≤ 0.05); 37% less (P = 0.11) fibre-bound CT IVOMD resulted when rumen liquid donors consumed browse containing CT. This indicates that (1) during IVOMD assays, rumen fluid donor diets should reflect, as closely as possible, those of the target animals and their diets, and (2) rumen liquid donor diet composition, especially forage CT concentrations, should be documented when evaluating results of IVOMD trials that use rumen liquor donors consuming CT.

Effects of phenolic compounds in three oak species on in vitro gas production using inoculums of two breeds of indigenous Iranian goats

The capabilities of rumen fluid (RF) from two indigenous Iranian goats (i.e., Markhoz, Alamout) to ferment tanniniferous (i.e., oak leaves) and non-tanniniferous (i.e., a mixture of lucerne hay and barley grain) feeds were studied. Five air dried samples from each of three oak species (i.e., Quercus persica, Quercus infectoria, and Quercus libani) were used to determine their chemical composition, phenolic compounds and protein precipitable phenolics (PPP). In three runs of in vitro gas production, the influence of non-tannin containing substrate incubated with either RF (i.e., Markhoz or Alamout) was assessed. Gas production (GP) was recorded from 1 to 96h of incubation. Effects of tannins on in vitro gas production, in vitro organic matter disappearance (IVOMD) and estimated metabolisable energy (ME) were assessed by a polyethylene glycol (PEG) tannin bioassay. There were no differences in gas production and IVOMD for a non-tannin substrate incubated with RF from either breed of goat. However, RF from Markhoz goats produced consistently more gas than RF from Alamout goats among oak species. The PEG treatment improved (P<0.01) the IVOMD in RF and estimated ME from both breeds of goats for all oak species. The RF from Markhoz goats fermented oak leaves more effectively than RF from Alamout goats, possibly due to the presence of tannin-degrading bacteria.

Herbage Nitrogen, Fiber, and In Vitro Disappearance of Three Great Plains Grasses during Establishment

ABSTRACTNative warm‐season grasses have the potential to provide summer grazing because of their adaptation and persistence. Little nutritive value information is available, however, on the effects of maturity and soil amendments for native North American warm‐season grasses during establishment. Multiflower false rhodesgrass (Chloris pluriflora E. Fourn.), pink pappusgrass (Pappophorum bicolor E. Fourn.), and plains bristlegrass [Setaria vulpiseta (Lam.) Roem. &amp; Schult.] were harvested monthly during the first 2 yr after establishment on a Windthorst sandy loam soil and fertilized with 0 or 67 kg N and P ha−1 yr−1 Spring application of fertilizer resulted in early season herbage N concentrations 58 to 79% greater (p ≤ 0.10) than unfertilized herbage and maintained N concentrations (p ≤ 0.10) above the 11.2 g kg−1 considered minimum for cattle maintenance through September for most entries. Multiflower false rhodesgrass had the least (p ≤ 0.10) fiber and greatest N and in vitro organic matter disappearance (IVOMD). During Year 1 and early in Year 2, IVOMD was sometimes greater (p ≤ 0.10) when goat rumen liquid was used compared to steer liquid. This relationship was nullified or even reversed as plants matured in Year 2, indicating that donor species of rumen liquid should be considered when interpreting IVOMD results for native warm‐season grasses.

Effects of Sown Season and Maturity Stage on In vitro Fermentation and In sacco Degradation Characteristics of New Variety Maize Stover

The effects of seedtime and maturity stage on nutritive value of five maize stover varieties, including conventional maize (Kexiangyu 11, CM), fodder maize (Huqing 1, FM), high oil maize (Gaoyou 115, HOM), sweet maize (Kexiangtianyu 1, SM) and waxy maize (Kexiangluoyu 1, WM), were examined based on chemical composition, in vitro gas production and in situ incubation techniques. Maize stover was sampled at d 17 and d 30 after tasseling, and designated as maturity stage 1 and stage 2, respectively. The average dry matter (DM) organic matter (OM), crude protein (CP) and fiber contents were the greatest for HOM, SM and FM, respectively. CM had the highest in vitro organic matter disappearance (IVOMD) and volatile fatty acid (VFA) concentration. The highest ammonia nitrogen (-N) concentration in the incubation solution, and effective degradability of DM () and neutral detergent fiber () were observed in SM. Advanced maturity stage increased (p and , but decreased (p-N concentration in the incubation solution and , but lower (pseedtime was observed running through almost all chemical composition, in vitro gas production parameters and in situ DM and NDF degradability. The overall results suggested that SM had the highest nutrient quality, and also indicated the possibility of selecting maize variety and seedtime for the utilization of maize stover in ruminants.

Steer Performance, Intake, and Digesta Kinetics of Switchgrass at Three Forage Masses

Management strategies to accommodate switchgrass (Panicum virgatum L.) in production systems have been reported but impact of variation in forage mass (FM) on animal responses and pasture stands are lacking. This 4‐yr study assessed canopy and stand characteristic and steer (Bos taurus) responses when ‘Kanlow’ switchgrass was continuously and variably stocked to produce Short (S) (10–16 cm), Medium (M) (20–26 cm), and Tall (T) (35–41 cm) canopy heights. From April to mid‐July (Period 1) FM for S, M, and T average 818, 2164, and 3294 kg ha−1, respectively. Canopies had similar in vitro organic matter disappearance (IVOMD) (626 g kg−1), but increased in neutral detergent fiber (NDF) from S (645 g kg−1) to T (665 g kg−1). Diets decreased in IVOMD from S (744 g kg−1) to T (706 g kg−1). Digesta kinetics data were not altered and average daily gain was similar among FM (1.11 kg d−1). From mid‐July to late September (Period 2), FM averaged 465, 1282, and 2388 kg ha−1, respectively, for S, M, and T. Whole canopy IVOMD increased from S (484 g kg−1) to T (538 g kg−1), whereas NDF was not altered (696 g kg−1). Steers selected a diet similar in IVOMD (685 g kg−1) and NDF (667 g kg−1) among FM. Estimates of dry matter intake (kg 100−1 kg body weight) increased from S (1.75) to T (2.54). Tiller density decreased from T to S. Continuously stocked switchgrass at 20 to 40 cm remained vegetative with 1279 tillers m−2 after 3 yr of grazing.

Effects of Forage Management on the Nutritive Value of Stockpiled Bermudagrass

‘Common’ and ‘Tifton 44’ bermudagrass [Cynodon dactylon (L.) Pers.] located near Fayetteville and Batesville, AR, respectively, were chosen to evaluate the effects of stockpiling initiation date (August or September), and N fertilization rate (0, 37, 74, or 111 kg N ha−1) on the nutritive value of fall‐stockpiled bermudagrass. At the Fayetteville location, there were initiation × harvest date interactions for acid detergent fiber (ADF, P = 0.003), hemicellulose (P = 0.003), cellulose (P = 0.0003), lignin (P = 0.007), and crude protein (CP, P = 0.008) in 2000, and strong interactions (P ≤ 0.001) for all response variables in 2001. Generally, neutral detergent fiber (NDF), ADF, cellulose, and lignin increased over harvest dates for both initiation dates in 2000, although increases for lignin were only numerical (P &gt; 0.05) for the September initiation date. Similar responses were observed for the August initiation date in 2001, but fiber components for the September 2001 initiation date declined over time because of contamination by other winter‐annual species. For August initiation dates in 2000 and 2001, in vitro organic matter disappearance (IVOMD) declined linearly (P ≤ 0.002) over harvest dates, reaching respective minima of 330 and 361 g kg−1. At the Batesville site, an N fertilization effect (P ≤ 0.017) was observed for NDF, ADF, and CP in both 2000 and 2001. A similar effect was observed for lignin (P = 0.001) and IVOMD (P &lt; 0.0001) in 2000, and for cellulose (P = 0.0004) during 2001. Fertilization with N at the initiation of stockpiling generally reduced fiber components, and increased CP; however, IVOMD was increased for 2000 only. As observed for the Fayetteville site, most fiber components increased over harvest dates, while IVOMD declined concomitantly. Generally, the nutritive value of stockpiled bermudagrass declines between mid‐October and mid‐December, and spring‐calving beef cows in the Upper South may need to be supplemented with energy to maintain body condition in the late fall or early winter.

Application of the 1996 NRC to Protein and Energy Nutrition of Range Cattle

AbstractBased on applications of the 1996 National Research Council (NRC) Nutrient Requirement of Beef Cattle (2000 update) model at our laboratories and on use of the model to evaluate published literature, it is our assessment that the NRC model (Level 1) represents an advancement in nutrient requirements of grazing cattle. We evaluated 8 published studies (35 treatment observations) to compare observed changes in body condition score (BCS) to those predicted by the NRC model, and to develop criteria to help with application of the model to range cattle nutrition. When in vitro organic matter disappearance (IVOMD) of grazed diets was converted to DE [DE = (1.07 - IVOMD) - 8.13] and used as a proxy for TDN, there were no differences in observed vs. predicted BCS change (P = 0.44). A critical component of the 1996 NRC model is the incorporation of the metabolizable protein system. An accurate estimate of microbial efficiency is key to application of the metabolizable protein system. We propose the use of an equation to adjust microbial efficiency for diets less that 65% TDN. The NRC model should be applied to 30-d time intervals if animal requirements or forage quality are changing rapidly. Accurate inputs for stage of gestation, days into lactation, breed, milk production, dietary TDN, and microbial efficiency are necessary for the model to yield accurate results. Work is needed to define and model microbial efficiency, nitrogen recycling, and the quality of diets selected by grazing livestock in various environments.

Performance of Cows and Their Calves Creep‐Grazed on Rhizoma Perennial Peanut

Where tropical grasses such as bahiagrass (Paspalum notatum Flügge) make up the base forage, creep‐grazing legumes should be beneficial to calf performance. Treatments of creep with rhizoma perennial peanut (Arachis glabrata Benth.) and no creep were set‐stocked (n = 24, 20, and 32 cow/calf pairs per treatment/replicate combination in 1997, 1998, and 1999, respectively) for an 84‐d grazing period (June–September). Base pasture forage dry matter (DM) availability was similar all 3 yr (avg. 2.81, 2.63, and 3.13 Mg ha−1 for 1997, 1998, and 1999, respectively) and for both treatments (2.84 and 2.87 Mg ha−1 for creep and no creep, respectively). Forage DM availability in the creep areas averaged approximately 3.0 Mg ha−1 and was composed of about 60% grass and 30% rhizoma perennial peanut (RPP). Nutritive value of RPP was usually 60 mg kg−1 higher for crude protein (CP) and 200 mg kg−1 higher for in vitro organic matter disappearance (IVOMD) compared with the associated grass (97.7 mg kg−1 CP and 415.8 mg kg−1 IVOMD). Utilization of creep area varied with year and breed of calf (Angus &lt; 10% vs. Romosinuano &gt; 50%). As a consequence, performance of Angus calves was not affected, but average daily gain (ADG) for Romosinuano calves with access to creep area was higher (+0.14 kg d−1) than that for calves with no creep. Also, body condition score (BCS) that was higher in August and September for creeped‐Romosinuano calves. Creep grazing the calves had no effect on cow performance (weight, ADG, or BCS).

AQUACULTURE EFFLUENT AS A WATER AND NUTRIENT SOURCE FOR HAY PRODUCTION IN THE SEASONALLY DRY TROPICS

In the water-limited environment of the U.S. Virgin Islands, tank culture of Tilapia (Oreochromis niloticus) is gaining importance. A by-product of intensive fish culture is a nutrient-rich wastewater (effluent). It is not known if effluent can replace the nitrogen (N) fertilizer required by guineagrass (Panicum maximum Jacq.) managed for hay. This study was conducted from 1997 to 1999 to compare the effects of irrigated aquaculture effluent (AE) and inorganic N rates of 60 kg ha1 (N60) and 0 (N0) on dry matter (DM) yield, forage crude protein concentration (CP), and in vitro organic matter disappearance (IVOMD), soil pH and phosphorous (P). Aquaculture effluent was applied at 2 cm ha1 wk1 to guineagrass for an 18-wk period in 1997 and 1999 but not in 1998. Guineagrass plots were harvested at eight-wk intervals (three eight-wk harvests in 1997, 1998, and 1999). Effluent DM yield (three harvests in 1997; 14.0 Mg ha−1) was similar (P > 0.05) to N60 (13.0 Mg ha−1). In 1998, effluent DM yield (three harvests; 13.7 Mg ha−1) was higher (P < 0.05) than N60 (9.8 Mg ha−1) suggesting a slow release N from the effluent. In 1999, AE out-yielded N60 by more than 50%. There was a trend for higher CP (9.6%) for the AE compared to (8.6%) for the N60 in 1997. In 1999, AE was two percentage units higher (P < 0.05) in CP (10.3%) compared to N60 (8.3%). In vitro organic matter disappearance in 1997 and 1999 were similar for all treatments and averaged 56% and 61%, respectively. There were no changes in soil pH (7.8) and P (22 mg kg−1), averaged across treatments. These results confirm that aquaculture effluent is an excellent N and water source for forages in the dry season and can replace the inorganic N requirements of guineagrass. The results should encourage the utilization of this effluent as a fertilizer rather than disposition to the environment.

Urea and(or) feather meal supplementation for yearling steers grazing limpograss (Hemarthria altissima var. 'Floralta') pasture.

The unique relationship between TDN and CP concentration (low CP relative to TDN) in the whole-plant of 'Floralta' limpograss (Hemarthria altissima) may provide an opportunity for improving cattle performance through protein supplementation. In each of three consecutive years, yearling Brahman x British crossbred steers (initial weight approximately 270 kg) grazed limpograss during the summer and fall (five steers per ha, three pasture replications per treatment) and were fed liquid cane molasses-based supplements (1.4 kg DM daily) alone, or containing urea and(or) hydrolyzed poultry feather meal. In yr 1 and 2, protein supplementation did not influence ADG. In these years, pasture availability was in excess at all times, and visual observations indicated that the upper canopy contained abundant leaf. Pasture samples collected in a manner to simulate grazing had in vitro organic matter disappearance (IVOMD):CP ratios ranging from 6.5 to 8.1, and plasma urea nitrogen concentration in the blood of steers fed no supplemental protein was high (10.6 to 15.9 mg/dL), both not suggestive of a situation where providing a protein supplement might improve animal performance. In yr 3, ADG was improved (P < 0.05) by protein supplementation. Forage availability was in excess at the beginning of the trial but declined significantly as the trial progressed. At the end of the trial, forage IVOMD:CP ratio (11.1) and plasma urea nitrogen values of steers fed no protein supplement (6.6 mg/dL) were both suggestive of a situation where providing supplemental protein might improve animal performance. Grazing management of limpograss pasture can affect canopy composition, thereby influencing cattle response to protein supplementation. In cases where limpograss is moderately grazed resulting in abundant leaf in the grazed horizon, dietary energy:protein ratio can be balanced, and positive responses to protein supplementation may not be observed. Where limpograss is grazed more intensively resulting in greater quantities of stem in the upper pasture canopy, an imbalance of dietary protein (low) relative to energy can develop, increasing the opportunity for enhancing cattle performance through protein supplementation.

Lamb production and forage quality under a forage system consisting of AU Triumph tall fescue and Tifton 44 bermudagrass

The lamb production potential and forage quality of a forage system consisting of AU Triumph fescue and Tifton 44 bermudagrass was studied over a period of two consecutive years. Each spring, 60 yearling Suffolk ewes and 40 wethers were divided into two groups and allowed to graze two replicated 1 ha AU Triumph paddocks continuously. At the end of the spring grazing season, both groups were transferred to two replicated 1 ha Tifton 44 paddocks for summer grazing. Body weight was recorded fortnightly and composite forage samples analyzed for chemical composition, in vitro dry matter disappearance (IVDMD) and in vitro organic matter disappearance (IVOMD) at the end of the study. Mean crude protein (CP), ether extract (EE), ash, neutral-detergent fiber (NDF), acid-detergent fiber (ADF), cellulose, lignin, IVDMD and IVOMD contents of AU Triumph fescue were 13.26, 1.86, 7.38, 69.4, 36.37, 29.2, 6.81, 64.44 and 62.88%, respectively. The corresponding values for Tifton 44 bermudagrass were 7.5, 1.01, 5.2, 78.3, 41.0, 28.3, 8.8, 56.97 and 55.61%. Average daily gain (ADG) and lamb gain per hectare on AU Triumph fescue were 142.1 g and 412.59 kg/ha, respectively. However, lamb ADG started to decline and remained low when they were transferred from AU Triumph to Tifton 44 bermudagrass resulting in a low ADG and lamb gain per hectare of only 18.2 g and 84.09 kg/ha, respectively. In contrast, Tifton 44 yielded higher post grazing residual DM, suggesting that the decline in performance of the lambs grazing Tifton 44 to be related to poor forage quality rather than availability. The results indicate that low nutritive value of Tiftton 44 bermudagrass is a limiting factor to lamb production in the forage system studied. To prevent the observed decline in lamb performance, it might be necessary to fertilize Tifton 44 at a higher rate or replace it with a better quality warm season forage.

Influence of Nitrogen on Productivity and Nutritive Value of Forage Chicory

Chicory (Cichorium intybus L.) is highly productive and responsive to N fertilization under midsummer conditions in the eastern USA. We conducted a field experiment for 3 yr on a Ramsey soil (loamy, siliceous, subactive, mesic Lithic Dystrudept) in southern West Virginia to determine if fertilizer N influenced forage chicory nutritive value and NO3–N concentration. Each N rate (0, 80, 160, 240, or 480 kg N ha−1) was replicated three times in a randomized block design. Swards were clipped at 6‐wk intervals during the growing season. Swards were virtually pure chicory in the first year (1994) regardless of N rate. By the third year (1996), chicory ranged from about 40% (0 N) to less than 5% (480 kg N ha−1) of swards. Botanical composition changes in the sward influenced dry matter (DM) response to N rate and herbage nutritive value. Dry matter production increased with N rate in 1994, but was not affected by N in 1996 when chicory was not a major sward component. More than 70% of total annual DM production in 1994 occurred after the first harvest, but by 1996 was less than 50%, reflecting productivity patterns typical of cool‐season swards. Nitrate concentrations in herbage were greatest (3.5 g kg−1) in 1995, a relatively dry year, and least (2.3 g kg−1) in 1996, when there was less chicory in the sward. Crude protein (CP) and in vitro organic matter disappearance (IVOMD) values indicated high forage quality throughout the course of the experiment.

Productivity, Botanical Composition, and Nutritive Value of Swards Including Forage Chicory

AbstractPure stands of ‘Grasslands Puna’ chicory (Cichorium intybus L.) are productive and responsive to N fertilization in the eastern USA. We conducted a field experiment for 3 yr to investigate productivity and nutritive value of swards including chicory, orchardgrass (Dactylis glomerata L.), and birdsfoot trefoil (Lotus corniculatus L.) as a function of clipping frequency (3‐ and 6‐wk intervals). Each treatment was replicated three times on an upland site of Dekalb series soil (loamy‐skeletal, mixed, subactive, mesic Typic Dystrochrept). Modest rates of N, P, and K were applied annually. Herbage mass, botanical composition, in vitro organic matter disappearance (IVOMD), and crude protein (CP) were determined. Cumulative herbage yield was not influenced by initial sward composition with chicory, chicory‐orchardgrass, and chicory–orchardgrass–trefoil averaging 6.8 Mg ha−1 during a growing season. Clipping frequency influenced yield with canopies clipped at 6‐wk intervals producing 26% more herbage than those clipped at 3‐wk intervals. Growth rates of canopies clipped at 6‐wk intervals averaged 51 kg ha−1 d−1 early in the growing season, suggesting that swards including chicory would be responsive to nutrient inputs and where rapid herbage regrowth and nutrient use by the growing crop are needed. Chicory declined in swards with time, regardless of initial sward composition or clipping frequency. Fluctuations in IVOMD and CP were related to changes in sward composition arising from the interaction of time and clipping frequency. Including orchardgrass and trefoil retarded invasion of less desirable species and so provided a means to control overall sward productivity and herbage composition.

Chicory Effects on Lamb Weight Gain and Rate of In Vitro Organic Matter and Fiber Disappearance

AbstractIn modern forage systems, there is increased emphasis on use of nontraditional forages to supply nutrients to livestock. Field and laboratory experiments were conducted to evaluate the utility and nutritive value of chicory (Cichorium intybus L.; CHIC) as a component of hill‐land pastures in Appalachia. In 1995, lamb (Ovis aries) gain was 56.1 kg ha−1 on orchardgrass (Dactylis glomerata L.; OG), while those grazing OG + CHIC lost 24.2 kg ha−1 during the 44‐d midsummer grazing period (P &lt; 0.05). In 1996, while weight gains were not different (P &gt; 0.10), total lamb production per hectare was 14% less on OG + CHIC (258 kg ha−1) than on OG only (300 kg ha−1) for the 79‐d grazing period. In 1997, total weight gained for the season was not different (P &gt; 0.10); lambs grazed OG or OG + CHIC for 110 d and production was 362 and 351 kg ha−1, respectively. Laboratory mixtures of 40:60 or 60:40 OG:CHIC had higher (P &lt; 0.05) in vitro organic matter disappearance (IVOMD), compared with 100% OG or 100% CHIC. There was a synergism in mixtures with orchardgrass that increased IVOMD relative to pure samples. Another laboratory experiment suggested that as total N increased in chicory herbage, rate of in vitro neutral‐detergent fiber (NDF) disappearance decreased. More information on the influence of soil type and management on chicory growth in pure stands and mixtures with other plant species is needed to optimize productivity of systems that include chicory.

Seasonal Cattle Management in 3 to 5 Year Old Bitterbrush Stands

Because of its high palatability and sustained levels of forage quality, antelope bitterbrush (Purshia tridentata Pursh DC) is one of the most desired shrubs on western U.S. rangelands. Bitterbrush has decreased in abundance in many areas, and efforts to foster its restoration have met with limited success. Because little information is available regarding the grazing management of newly established stands of bitterbrush, this study was undertaken to: 1) determine the effects of early and late-season cattle grazing on bitterbrush, 2) determine when cattle were most likely to forage on these shrubs, and 3) relate use of shrubs to the quantity, quality, and phenology of accompanying herbaceous forages. Ungrazed (control), early-grazed, and dormant-grazed paddocks supporting 3+ year old bitterbrush (randomized complete block design, N = 3) were monitored for 3 years to accomplish this task. When grasses were green and growing, cattle grazed about 6% of the shrubs per day. When grasses and forbs were dormant, about 13% of the shrubs were grazed each day. Rates of use of shrubs were not significantly (P > 0.05) correlated with amounts of accompanying herbage available (r(2) = 0.40), levels of forage utilization (r(2) = 0.00), stocking pressure (r(2) = 0.00), crude protein (r(2) = 0.02) or neutral detergent fiber content (r(2) = 0.59) of accompanying forages, or digestibility of the forages as measured by in-vitro organic matter disappearance (IVOMD) (r(2) = 0.62). In step-wise regression analyses Julian date alone accounted for 92% of the variation in rates of use of shrubs and the addition of IVOMD accounted for 98% of the variation. This suggested that bitterbrush was grazed more heavily as the growing season advanced and forage quality of the grasses declined. Shrub height, diameter, and volume were reduced by early grazing in 1 of 3 years when turn out was delayed until grasses were entering anthesis. Cattle grazing when grasses were dormant caused reductions in height, diameter, and volume of the shrubs in all 3 years. Rates of shrub mortality were unaffected by treatment. Bitterbrush in all treatments experienced significant reductions in height, diameter, and volume from wildlife use during the winters of 1993 and 1994 but not 1995. When trials were terminated, shrubs in early-grazed paddocks exceeded (P < 0.10) their counterparts in the dormant grazed paddocks in height, diameter, and volume.

Evaluation of berseem clover in diets of ruminants consuming corn crop residues.

Berseem clover hay was compared to alfalfa hay provided at 0, 25, and 50% of the diet DM in mixtures with corn crop residues to wether lambs. Berseem clover hay had lower (P < .05) concentrations of NDF, ADF, and CP than alfalfa hay. The digestibility of DM, DMI, and N balance did not differ (P > .05) between diets containing alfalfa hay or berseem clover hay. To evaluate stockpiled berseem clover as a supplement for grazed corn crop residues, berseem clover and oats were incorporated into a corn-corn-oat/berseem clover crop rotation for 3 yr in replicated 6.1-ha fields. Two cuttings of oat-berseem clover hay were harvested each summer before forage was stockpiled for winter grazing. After corn grain harvest, multiparous and primiparous crossbred cows in midgestation were allotted to each field at 1.01 ha/cow to strip-graze corn crop residues with or without stockpiled berseem clover or allocated to replicated drylots for 98 to 140 d. Each group was offered alfalfa-grass hay as large bales to maintain a mean body condition score of 5 on a 9-point scale. Mean rates of total and digestible OM disappearance from grazed and ungrazed field areas of berseem clover and corn crop residues did not differ over the 3 yr. In vitro organic matter disappearance (IVOMD) tended to decrease more rapidly (P = .13) and NDF and ADF concentrations increased more rapidly (P < .05) in berseem clover than in corn crop residues. Seasonal BW change did not differ (P > .05) between winter management systems in any year, and seasonal body condition score changes did not differ (P > .05) between cows grazing corn crop residues and berseem clover and those maintained in a drylot in yr 2 and 3. Cows grazing corn crop residues with or without berseem clover required less (P < .05) hay than those maintained in drylot. Although the effects of berseem clover hay supplementation on the intake and digestibility of corn crop residues do not differ from alfalfa hay, the nutritional value of stockpiled berseem clover decreases rapidly during winter, limiting its value as a standing supplement for corn crop residues in late winter.