@article{burns_fisher_pond_2011, title={Flaccidgrass Forage Mass and Canopy Characteristics Related to Steer Digesta Kinetics and Intake}, volume={51}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2011.05.0284}, abstractNote={ABSTRACT ‘Carostan’ flaccidgrass ( Pennisetum flaccidum Griseb.) has potential as a perennial, warm‐season grass for pastures. This 2‐yr study examined digesta kinetics, dry matter intake (DMI), and diet of steers as related to canopy characteristics. Steers ( Bos taurus L.) were continuously and variably stocked at canopy heights of Short (15 to 20 cm), Medium (30 to 40 cm), and Tall (45 to 55 cm) with forage mass (FM) of 1245, 2600, and 3585 kg ha −1 , respectively (linear; p < 0.01). Neither mean retention time nor passage rate of either liquid or digesta phases were altered by FM. Fecal output increased linearly ( p = 0.04) from Short to Tall (0.643 to 0.739 kg 100 −1 kg body weight [BW]) indicating a possible variation in DMI. However, DMI and digestible DMI (based on leaf in vitro dry matter disappearance [IVDMD]) were similar among FM (mean = 1.99 and 1.29 kg 100 −1 kg BW). Leaf composed 24.3% of the three canopies and was not altered by FM. Stem increased linearly ( p = 0.01) from 40.1 to 53.1% with height whereas dead tissue declined linearly ( p = 0.06) from 34.8 to 23.4%. Steers selected diets (1 yr data), regardless of FM, similar in IVDMD (mean = 713 g kg −1 ) and neutral detergent fiber (NDF) (mean = 486 g kg −1 ). In general, steer digesta kinetics were not influenced by FM as animals adjusted grazing behavior to result in similar responses. Flaccidgrass canopies were flexible and no particular optimum FM was detecting for an optimum diet. The influence of FM on pasture productivity (regrowth after defoliation) requires additional study.}, number={6}, journal={CROP SCIENCE}, author={Burns, J. C. and Fisher, D. S. and Pond, K. R.}, year={2011}, month={Nov}, pages={2895–2903} }
 @article{burns_fisher_2011, title={Stocking Strategies as Related to Animal and Pasture Productivity of Endophyte-Free Tall Fescue}, volume={51}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2011.01.0022}, abstractNote={ABSTRACT Tall fescue ( Festuca arundinacea Schreb.) is a well adapted perennial grass used for pasture across the north–south transition zone in the United States. This 3‐yr trial evaluated three stocking strategies to utilize well‐fertilized spring (April to July) growth of endophyte‐free tall fescue for steer and pasture production. Continuous stocked (CS) was compared with a daily allowance (DA) or lax rotation (LR) (7 to 12 d). Forage mass (in kilograms per hectare) averaged 2673 for CS, 3057 at turn on and 2844 residual for DA, and 2851 at turn on and 2559 residual for the LR. Canopies were similar being mainly leaf (54.9%), followed by dead (32.6%), stem (11.9%), and head (0.5%) fractions. Steer daily gains (0.95 kg), stocking rate (6.7 steers ha −1 ), gain per hectare (585 kg), and effective feed units (3111 kg ha −1 ) were similar among stocking strategies. Canopy in vitro true organic matter disappearance (IVTOD) was similar (747 g kg −1 ) among treatments but differed in crude protein (CP), averaging 186 g kg −1 for CS vs. 198 g kg −1 for rotations. Furthermore, DA was less in CP than LR (189 vs. 207 g kg −1 ) but greater in neutral detergent fiber (NDF) (623 vs. 594 g kg −1 ). Diet selected was similar among treatments in IVTOD (885 g kg −1 ), CP (245 g kg −1 ), and NDF (457 g kg −1 ) as was daily grazing time of 11.5 h when monitored by Vibracorder or 12.3 h when monitored by computer. Well‐fertilized tall fescue pastures free of toxic endophyte can accommodate a range of stocking strategies when efficiently utilized in animal production systems.}, number={6}, journal={CROP SCIENCE}, author={Burns, J. C. and Fisher, D. S.}, year={2011}, month={Nov}, pages={2868–2877} }
 @article{burns_fisher_2010, title={Eastern Gamagrass Management for Pasture in the Mid-Atlantic Region: I. Animal Performance and Pasture Productivity}, volume={102}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2009.0265}, abstractNote={Eastern gamagrass [ Tripsacum dactyloides (L.) L.] (EG) is a native, warm‐season perennial grass with potential as pasture for the eastern United States, but its value has not been well studied. The objective of this 4‐yr experiment was to estimate forage mass (FM) for EG that maximizes steer ( Bos taurus ) performance and pasture productivity. Five treatments (three continuously and two rotationally stocked) were compared with a continuously stocked ‘Coastal’ bermudagrass [ Cynodon dactylon (L.) Pers.] control. The three continuously stocked treatments had mean FM (10‐cm stubble) levels of 559 kg ha −1 (Short), 1103 kg ha −1 (Medium), and 1932 kg ha −1 (Tall). Rotational treatments consisted of two subdivisions with steers moved on a 10 to 14 d interval (FM = 1348 kg ha −1 ) and10 subdivisions with steers moved every 3 to 4 d with a 27 to 36 d regrowth interval (FM = 2061 kg ha −1 ). The average daily gain (ADG) from the Medium continuously stocked treatment was greatest at 0.90 kg ( P = 0.02) and produced similar annual gain per hectare (735 vs. 749 kg ha −1 ; P = 0.08) as Short. Rotational pastures had greater FM than continuously stocked (1705 vs. 1198 kg ha −1 ; P = 0.03), but the least ADG (0.67 vs. 0.79 kg; P = < 0.01). Bermudagrass produced less ADG than EG (0.57 vs. 0.79 kg; P < 0.01), but gain per hectare was similar (662 kg ha −1 ) and stocking rate was greater (10.0 vs. 6.7 head ha −1 ; P < 0.01). Eastern gamagrass has potential as a special purpose pasture for the region when greater ADG is the goal.}, number={1}, journal={AGRONOMY JOURNAL}, author={Burns, J. C. and Fisher, D. S.}, year={2010}, pages={171–178} }
 @article{burns_fisher_2010, title={Eastern Gamagrass Management for Pasture in the Mid-Atlantic Region: II. Diet and Canopy Characteristics, and Stand Persistence}, volume={102}, ISSN={["0002-1962"]}, DOI={10.2134/agronj2009.0339}, abstractNote={Eastern gamagrass [ Tripsacum dactyloides (L.) L.] (EG), a native warm‐season perennial grass, lacks evaluation for use in grazing systems. Our objective was to test EG in a 4‐yr experiment to estimate forage mass (FM) that maximizes steer ( Bos taurus ) performance and pasture productivity. Pasture canopy characteristics, diet selection by grazing steers, and stand persistence from EG continuously grazed at Short, Medium, and Tall heights and two rotationally stocked treatments were compared with continuously stocked ‘Coastal’ bermudagrass [ Cynodon dactylon (L.) Pers.] (BG). The EG had proportionally more green leaf (78.2 vs. 24.5%), less stem (4.4 vs. 45.2%), less heads (0.4 vs. 5.6%), and similar dead tissue (17.0 vs. 24.8%). Plant fractions were similar in proportion among EG treatments. Digestible leaf mass was greater in EG than in BG ( P < 0.01; 713 vs. 292 kg ha −1 ) and dominated the EG canopies with a linear ( P < 0.01) increase in leaf mass with increasing FM (194–922 kg ha −1 ). Diets were similar in IVTOD (738 g kg −1 ), CP (151 g kg −1 ), and NDF (654 g kg −1 ) when continuously stocked but greater ( P < 0.01) in IVTOD (791 g kg −1 ), and least in NDF (624 g kg −1 ) from the rotation. Stand declined linearly ( P = 0.09) with decreasing FM (Tall = 34.5 and Short = 11.7% basal cover) but was similar between the two rotational systems (35.5%). Continuously stocking EG at about 38 cm gave greatest steer daily gain but rotations may prevent declines in stands with some sacrifice in gains.}, number={1}, journal={AGRONOMY JOURNAL}, author={Burns, J. C. and Fisher, D. S.}, year={2010}, pages={179–186} }
 @article{burns_fisher_2010, title={Intake and Digestibility of Improved Selections of Tall Fescue and Orchardgrass Hays}, volume={50}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2009.03.0157}, abstractNote={ABSTRACT Improved cool‐season grass cultivars may add production potential to ruminant enterprises across the North–South transition zone. Quality among hays of ‘MaxQ’ (‘Jesup’ with novel endophyte), HM4 (‘HiMag’ with novel endophyte No. 4) and ‘Cajun’ (without endophyte) tall fescues [ Lolium arundinaceum (Schreb.) Darbysh.] and ‘Persist’ orchardgrass ( Dactylis glomerata L.) was evaluated. Forage was harvested in the flag‐leaf stage in three of 4 yr and a regrowth (late flag‐leaf to heads‐emerging stage) in 1 yr. Goats (four trials) consumed MaxQ, HM4, and Persist similarly ( P = 0.12; mean = 2.49 kg 100 −1 kg body weight [BW]) and Cajun least ( P < 0.01; mean = 1.62 kg × 100 −1 kg BW). Apparent digestibility was similar among tall fescues ( P ≥ 0.07; mean = 609 g kg −1 ), but MaxQ and Cajun were greater than Persist ( P ≤ 0.05; mean = 610 and 623 vs. 582 g kg −1 ). Digestible dry matter intake (DMI) was similar among MaxQ, HM4, and Persist ( P ≥ 0.09; mean 1.49 kg 100 −1 kg BW). Steers (three trials and Cajun not evaluated) consumed more Persist than MaxQ ( P = 0.01; 2.40 vs. 2.14 kg 100 −1 kg BW) or HM4 ( P = 0.01; 1.98 kg 100 −1 kg BW). MaxQ had greater apparent digestibility than HM4 ( P = 0.01) or Persist ( P = 0.04; 626 vs. 585 vs. 597 g kg −1 , respectively) but digestible DMI of MaxQ and Persist was similar ( P = 0.12; mean = 1.39 kg 100 −1 kg BW). Improved tall fescue cultivars, with novel endophyte, offer the ruminant producer a cool‐season forage of similar quality as orchardgrass for their enterprise.}, number={1}, journal={CROP SCIENCE}, author={Burns, J. C. and Fisher, D. S.}, year={2010}, pages={419–426} }
 @article{burns_fisher_2007, title={Dry matter intake and digestibility of 'Coastal', 'Tifton 44', and 'Tifton 85' bermudagrass hays grown in the US upper south}, volume={47}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci06.04.0253}, abstractNote={ABSTRACT ‘Coastal’ bermudagrass [ Cynodon dactylon (Pers.) L.] is the major warm‐season grass grown across the U.S. upper south. More recent hybrids of ‘Tifton 44’ (T44) and ‘Tifton 85’ (T85) ( Cynodon sp.) offer improved nutritive value. Compared are dry matter (DM) intake and digestion of Coastal bermudagrass (CB), T44, and T85 hays grown under different soil and climate conditions and harvested at either the same or different maturities. In the comparison of CB and T44 with steers ( Bos taurus L.), DM intake was greater for CB in one of three experiments, whereas intakes did not differ in the other two. Greater intake for CB was associated with greater DM digestion. In the other two experiments, T44 had greater DM digestion than did CB in one trial but did not differ in the other. Hays of CB, T44, and T85, harvested in 2 yr, were compared by means of sheep ( Ovis aries L.). In Year 1, sheep consumed more CB than either T44 or T85, whereas in Year 2, no differences in intake were detected. Coastal was digested least in both experiments compared with T44 and T85, and T85 had greatest DM digestion in one of the two years. Samples of masticate of CB had the least in vitro true dry matter disappearance (IVTDMD) with T44 intermediate and T85 generally greatest. In general, animal response data showed little advantage of T44 in comparison with CB; however, Tifton 85 appears to have greater digestible fiber and offers potentially greater DM digestion and digestible intake compared with CB.}, number={2}, journal={CROP SCIENCE}, author={Burns, J. C. and Fisher, D. S.}, year={2007}, pages={795–810} }
 @article{burns_fisher_rottinghaus_2006, title={Grazing influences on mass, nutritive value, and persistence of stockpiled Jesup tall fescue without and with novel and wild-type fungal endophytes}, volume={46}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2005.09-0327}, abstractNote={Introducing novel endophytes into tall fescue ( Festuca arundinacea Schreb.) that produce no ergot alkaloids could prevent negative impacts on animal performance while improving plant persistence. This 3‐yr study evaluated ‘Jesup’ tall fescue (TF) for forage mass, nutritive value, and stand persistence when containing no endophyte, a novel endophyte (no ergot alkaloids), or a wild‐type endophyte (ergot alkaloids). Forage was accumulated from mid‐August and treatments consisted of (i) a grazed control (grazed when growth approximated 10 to 15 cm), or forage accumulated and grazed in (ii) mid‐November, (iii) mid‐December, (iv) mid‐January, and (v) mid‐February. Endophyte status had no influence on total forage mass; forage removed by grazing; proportion of leaf, stem, and dead fractions; or on nutritive value (except ergovaline which was greatest in the wild type). Delaying defoliation linearly reduced forage mass, ergovaline concentration, and nutritive value. All stands of TF declined with losses similar ( P = 0.37) for wild‐type and novel stands (29 vs. 42%) but were greatest for the TF without an endophyte (29 vs. 75%; P = 0.01 and 42 vs. 75%; P = 0.04). These data support the use of novel endophytes in TF for animal production and caution against the use of endophyte‐free TF because of decreased stand longevity. The presence of ergovaline can be minimized by stockpiling TF with utilization after late autumn but occurs with a sacrifice in forage mass and nutritive value.}, number={5}, journal={CROP SCIENCE}, author={Burns, J. C. and Fisher, D. S. and Rottinghaus, G. E.}, year={2006}, pages={1898–1912} }
 @article{burns_mayland_fisher_2005, title={Dry matter intake and digestion of alfalfa harvested at sunset and sunrise}, volume={83}, DOI={10.2527/2005.831262x}, abstractNote={The preference exhibited by animals in selecting one feed over another is important only if the preferred diet is consumed daily in larger quantities, digested to a greater extent, or both. Six alfalfa (Medicago sativa L.) hays were harvested in pairs at sunset (PM) and sunrise (AM) on consecutive days at three harvest dates. A previous study of these hays demonstrated differences in ruminant preference favoring PM harvests. This study evaluated the effects of time of cutting and harvest date on voluntary DMI and nutrient digestibility. The hays were field-cured, baled, and chopped before evaluation for intake and digestibility. Studies were conducted for sheep (Ovis aries), goats (Capra hircus), and cattle (Bos taurus). Goats, but not steers or sheep, demonstrated differences in nutrient digestibility between PM- and AM-cut hays. Goats consumed more PM than AM hay (2.97 vs. 2.83 kg/100 kg of BW; P = 0.07) and digested it to a greater extent (0.710 vs. 0.696; P = 0.03), resulting in greater digestible DMI (2.11 vs. 1.97 kg/100 kg of BW; P = 0.03). Sheep consumed (mean = 2.52 kg/100 kg of BW; P = 0.59) and digested (mean = 0.681; P = 0.25) PM- and AM-cut hays similarly. Steers consumed larger quantities of PM-than AM-cut hay (2.90 vs. 2.62 kg/100 kg of BW; P = 0.11), but digestion did not differ with cutting time (mean = 0.660; P = 0.75). Difference values (composition of fed hay minus composition of orts) indicated that sheep and goats selected from the feed offered similarly, whereas steers selected differently. Difference values for CP averaged 94 and 101 g/kg for goats and sheep and 32 g/kg for steers (P < 0.01), and difference values for NDF averaged 185 and 196 g/kg for goats and sheep and 73 g/kg for steers (P <or= 0.01). Steer DMI and digestible DMI were associated with preference (r = +0.83, P <or= 0.05; and r = +0.89, P <or= 0.05) and with coordinates for preference criteria (dimension 1; r = +0.90, P <or= 0.05; and r = +0.89, P <or= 0.05) from a previous preference trial. Intake and digestion responses for goats and sheep showed no relationship with the previous preference trial measurements. For cattle and goats, the management strategy of mowing in the afternoon seems to take advantage of small, but influential diurnal changes in the soluble carbohydrate fraction and offers the potential to improve forage quality.}, number={1}, journal={Journal of Animal Science}, author={Burns, J. C. and Mayland, H. F. and Fisher, D. S.}, year={2005}, pages={262–270} }
 @article{stevens_burns_fisher_eisemann_2004, title={The  influence of high-nitrogen forages on the voluntary feed intake of sheep}, volume={82}, DOI={10.2527/2004.8251536x}, abstractNote={The objective of this research was to examine the effect of high concentrations of nonprotein nitrogen (NPN) on the voluntary food intake of sheep fed high-quality grasses. Wether lambs (n = 6 per treatment) were fed dried switchgrass (Panicum virgatum L.; Exp. 1) or dried tall fescue (Festuca arundinacea Schreb.; Exp. 2). In both experiments, urea was added to the dried forage at 0 (control), 12, or 24 g of N/kg of DM to increase the NPN concentration. Acid detergent fiber concentrations were 305 g/kg of DM in both experiments, although DM digestibility was 663 and 618 g/ kg of DM in Exp. 1 and Exp. 2, respectively. Voluntary feed intake of the control forage was 28.2 and 19.1 g/ kg of BW in Exp. 1 and Exp. 2, respectively, and decreased for the high-urea treatments to 25.2 and 16.2 g/kg of BW in Exp. 1 (P = 0.07) and Exp 2 (P = 0.03), respectively. Total feed N concentrations increased from 29.5 g to 45.7 g of N/kg of DM in Exp. 1 (P < 0.01) and from 28.4 to 55.9 g of N/kg of DM in Exp. 2 (P < 0.01). Nonprotein N concentrations increased from 28.3 to 53.8% of the total N in switchgrass diets (Exp. 1; P < 0.01), and from 26.4 to 64.0% in tall fescue diets (Exp. 2; P < 0.01). Plasma urea concentrations of the lambs increased from 3.1 to 6.6 mM (Exp. 1; P < 0.01) and from 2.9 to 5.8 mM (Exp. 2; P < 0.01) as the amount of urea added to the diets increased. These changes resulted in an increase in plasma osmolality from 298 to 307 mOsm/kg (Exp. 1; P = 0.04), and from 299 to 307 mOsm/kg (Exp. 2; P = 0.06). Increasing feed N and NPN concentrations through the addition of urea caused a significant decrease in the voluntary feed intake of sheep fed tall fescue and switchgrass. These responses showed no significant cause-and-effect relationship between voluntary feed intake, plasma urea concentrations, and plasma osmolality.}, number={5}, journal={Journal of Animal Science}, author={Stevens, D. R. and Burns, J. C. and Fisher, D. S. and Eisemann, J. H.}, year={2004}, pages={1536–1542} }
 @article{fisher_mayland_burns_2002, title={Variation in ruminant preference for alfalfa hays cut at sunup and sundown}, volume={42}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2002.0231}, number={1}, journal={CROP SCIENCE}, author={Fisher, DS and Mayland, HF and Burns, JC}, year={2002}, pages={231–237} }
 @article{burns_fisher_mayland_2001, title={Preference by sheep and goats among hay of eight tall fescue cultivars}, volume={79}, DOI={10.2527/2001.791213x}, abstractNote={Grazing ruminants use both visual cues and taste in selecting their diet. Preference during grazing may not be the same when forage is dried for hay and cut into lengths prior to feeding in confinement. Eight cultivars of tall fescue (Festuca arundinacea Schreb.), previously evaluated for preference while grazed, were harvested three times over a period of 2 yr. The hays were air-dried, baled, and passed through a hydraulic bale processor prior to feeding. Five experiments were conducted. All three harvests were evaluated with sheep and the last two also with goats, using six animals each time. During an adaptation phase, hays were offered alone as meals. In the experimental phase, every possible pair of hays (28 pairs) was presented for a meal. Data were analyzed by multidimensional scaling and by traditional analyses. Preference was significant among cultivars in all experiments. Multidimensional scaling showed that selection was based on two criteria with two dimensions being significant. Sheep preferred KENHY followed by KENTUCKY 31 and STARGRAZER but preferenced against BARCEL. HIMAG, MO-96, and C1 were intermediate and MOZARK was variable. Goats were similar to sheep in preferring KENHY followed by STARGRAZER and selected against MOZARK and BARCEL. KENTUCKY 31, HIMAG, MO-96, and C1 were intermediate. In all five experiments, the general association was positive for available carbohydrate fractions and negative for fiber fractions that contribute to cell wall rigidity.}, number={1}, journal={Journal of Animal Science}, author={Burns, J. C. and Fisher, D. S. and Mayland, H. F.}, year={2001}, pages={213–224} }
 @article{luginbuhl_pond_burns_fisher_2000, title={Intake and chewing behavior of steers consuming switchgrass preserved as hay or silage}, volume={78}, DOI={10.2527/2000.7871983x}, abstractNote={Effect of preservation method on intake and chewing behavior was examined using a first, late vegetative harvest (mid-June) of Kanlow switchgrass (Panicum virgatum L.). For silage (S), forage was harvested with a commercial field chopper (1.5 to 4 cm average chop length) and ensiled directly in silos 1.2 m in diameter and 3.6 m in height. For hay (H), forage was harvested with a flail-chopper (7 to 15 cm average chop length) and cured as hay in a drier at 77 degrees C. Diets of H and S were fed to six Hereford steers (338+/-5 kg) in a single crossover experiment. Chewing behavior was monitored for 4 d with a computerized system. At feeding, H was higher in DM and contained greater concentrations (DM basis) of NDF, CP, and hemicellulose, but lower concentrations of ADF and cellulose, and had lower in vitro DM disappearance values. Steers fed S had higher intakes of DM (P < .02) and NDF (P < .04) and consumed less water from the water supply (P < .01) than animals fed H. However, total amount of water (from water supply and feed) consumed per kilogram of DMI did not differ between diets. Crude protein intake was similar between diets. Preservation method had no effect on eating time, number of boli ruminated, bolus duration, and number of rumination chews per bolus. Steers fed S made fewer eating chews (P < .10) and ruminated for a longer time (P < .05) while making a greater number of rumination chews (P < .04) than steers fed H. Rumination intercycle time was slightly shorter in steers fed H (P < .05) than in steers fed S. When expressed per kilogram of NDF intake, steers fed S spent less time eating (P < .03) and made fewer eating chews (P < .02) than steers fed H; however, rumination time, number of rumination chews, and number of boli ruminated were not affected by preservation method. Steers fed S ingested feed at a greater rate (P < .03), excreted smaller fecal particles (P < .03), had meals of shorter duration (P < .06), spent less time eating during main meals (meals following feed distribution: P < .05), had more rumination periods (P < .01), and a shorter morning (P < .06) latency time (interval between end of main meal and onset of rumination) than steers fed H. These results indicate that preservation method with its concomitant differences in chop length affected forage chemical composition and voluntary intake, and that differences in chewing behavior occurred mostly during eating.}, number={7}, journal={Journal of Animal Science}, author={Luginbuhl, J. M. and Pond, K. R. and Burns, J. C. and Fisher, D. S.}, year={2000}, pages={1983–1989} }
 @article{merkel_pond_burns_fisher_2000, title={Rate and extent of dry matter digestibility in sacco of both oven- and freeze-dried Paraserianthes falcataria, Calliandra calothyrsus, and Gliricidia sepium}, volume={77}, number={1}, journal={Tropical Agriculture}, author={Merkel, R. C. and Pond, K. R. and Burns, J. C. and Fisher, D. S.}, year={2000}, pages={1–5} }
 @article{merkel_pond_burns_fisher_1999, title={Intake, digestibility and nitrogen utilization of three tropical tree legumes I. As sole feeds compared to Asystasia intrusa and Brachiaria brizantha}, volume={82}, ISSN={["0377-8401"]}, DOI={10.1016/S0377-8401(99)00094-2}, abstractNote={The tropical tree legumes Paraserianthes falcataria , Gliricidia sepium , and Calliandra calothyrsus were fed to ram lambs to evaluate their potential as feeds. Dry matter intake, digestibility of dry matter, neutral detergent fiber and nitrogen, and digestible energy content were determined through a digestion study. The herbaceous dicot Asystasia intrusa was included as an underutilized source of nitrogen and Brachiaria brizantha was included as a standard tropical (C 4 ) grass. Of the tree legumes, C. calothyrsus had the highest level of soluble phenolics (SPHE), averaging 38% of dry matter, and soluble proanthocyanidins (SPRO), averaging 13.7 absorbance units per gram (AU g −1 ) of dry matter. P. falcataria was intermediate, averaging 15% SPHE and 4.8 AU g −1 SPRO, with G. sepium the lowest, with 5% SPHE and 0.4 AU g −1 SPRO. Dry matter intake (percent of body weight) was lowest for C. calothyrsus -fed lambs, averaging 2.0%, compared with 3.2% for P. falcataria and 2.5% for G. sepium . Intakes were similar for A. intrusa and B. brizantha , averaging 2.6%. C. calothyrsus also had the lowest dry matter digestibility, averaging 55%, compared with 61% for P. falcataria and 63% for G. sepium , which were similar. Highest dry matter digestibility was obtained for A. intrusa , averaging 72%, and B. brizantha , averaging 65%. Forages had similar rank for neutral detergent fiber digestibility. Proanthocyanidins in the tree legumes may have bound with cell wall carbohydrates, resulting in a reduction in dry matter and NDF digestibilities. Digestible energy (kcal g −1 ) was highest for G. sepium , averaging 3.0, and ranged from 2.6 to 2.7 kcal g −1 for C. calothyrsus , P. falcataria , A. intrusa and B. brizantha . Fecal N was higher from the lambs fed tree legumes (average, 0.419 g kg −1 BW/day) compared with A. intrusa or B. brizantha (0.261 and 0.159 g kg −1 BW/day, respectively). This was attributed to higher fecal NDF-N, averaging 0.329 g kg −1 BW/day, from the tree legumes versus 0.162 g kg −1 BW/day for A. intrusa and 0.048 g kg −1 BW/day for B. brizantha . Consequently, apparent and true N digestibilities were lower for the tree legumes, averaging 61 and 69%, respectively, versus 73 and 84% for A. intrusa , and 76 and 93% for B. brizantha . Within the tree legumes, C. calothyrsus had lowest apparent and true N digestibility, averaging 51 and 57%, while P. falcataria and G. sepium had apparent and true N digestibilities averaging 67 and 76%. Proanthocyanidins and phenolic compounds in the three legumes, especially C. calothyrsus , were associated with reduced forage quality.}, number={1-2}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Merkel, RC and Pond, KR and Burns, JC and Fisher, DS}, year={1999}, month={Nov}, pages={91–106} }
 @article{merkel_pond_burns_fisher_1999, title={Intake, digestibility and nitrogen utilization of three tropical tree legumes II. As protein supplements}, volume={82}, ISSN={["0377-8401"]}, DOI={10.1016/S0377-8401(99)00095-4}, abstractNote={Calliandra calothyrsus, Paraserianthes falcataria and Gliricidia sepium leaves were supplemented at both 25 and 50% of dietary crude protein to a basal concentrate and fed to growing ram lambs. A control diet consisted of concentrate and the forage grass Brachiaria brizantha. Dry matter intakes and ADG of tree legume supplemented treatments were lower (P < 0.05) than control lambs, but increasing the amount of tree leaves fed did not result in further decreases in either dry matter intake or ADG. Dry matter digestibility was lower (P < 0.05) in both 25 and 50% dietary treatments compared with the control, while NDF digestibility was lower (P < 0.001) only in the 50% dietary treatments. Increasing the amount of leaves fed from all three tree species, led to decreased NDF digestibility. Fecal NDF-N was higher in tree-supplemented groups (P < 0.01) compared with control and increased (P < 0.05) with increasing amounts of tree leaves fed. Both apparent and true N digestibility were lower (P < 0.05) in C. calothyrsus, than in the other tree legume treatments. True N digestibility of 91% for the control was higher (P < 0.01) than the tree legume treatments supplemented at both 25 (range, 83–86%) and 50% dietary CP (range, 74–79%). Increasing the amount of tree leaves fed, regardless of tree species, decreased N digestibility in the diets. Higher fecal NDF-N and lower N digestibility in tree leaf supplemented lambs indicated that condensed tannins present in these tree species were binding protein and rendering it less available for digestion. Supplementation with C. calothyrsus, which had the highest levels of SPHE and SPRO, affected N utilization more negatively than did supplementation with either P. falcataria or G. sepium.}, number={1-2}, journal={ANIMAL FEED SCIENCE AND TECHNOLOGY}, author={Merkel, RC and Pond, KR and Burns, JC and Fisher, DS}, year={1999}, month={Nov}, pages={107–120} }
 @article{fisher_mayland_burns_1999, title={Variation in ruminants' preference for tall fescue hays cut either at sundown or at sunup}, volume={77}, DOI={10.2527/1999.773762x}, abstractNote={Plants vary diurnally in concentrations of nonstructural carbohydrates. If ruminants prefer forages with higher total nonstructural carbohydrates (TNC), then the preference for hays harvested within the same 24-h period may vary. An established field of tall fescue (Festuca arundinacea Schreb.) was harvested six times in the vegetative stage. Harvests were paired such that each cutting at sundown (PM) was followed by a cutting the next morning at sunup (AM). We harvested in this manner three times, resulting in six hays. The hays were field-dried, baled, and passed through a hydraulic bale processor prior to feeding. Experiments were conducted with sheep, goats, and cattle, using six animals in each case. During an adaptation phase, hays were offered alone as meals. In the experimental phase, every possible pair of hays (15 pairs) was presented for a meal. Data were analyzed by multidimensional scaling and by traditional analyses. Multidimensional scaling indicated that selection was based on a single criterion. Preference for PM hays was greater than for AM hays (P < .01) in all experiments. Increased preference was associated with increased TNC (P < .01) and in vitro true DM disappearance (P < .01) and decreased fiber concentration (P < .01; NDF, ADF, cellulose, and ADL). Mowing hay late in the day was effective in increasing forage preference.}, number={3}, journal={Journal of Animal Science}, author={Fisher, D. S. and Mayland, H. F. and Burns, J. C.}, year={1999}, pages={762–768} }
 @book{belesky_burns_chamblee_daniel_ruiter_fisher_green_mochrie_mueller_pond_et al._1998, title={Carostan flaccidgrass: Establishment, adaption, production management, forage quality, and utilization}, publisher={Raleigh, NC: N.C. Agricultural Research Service, N.C. State University}, author={Belesky, D. P. and Burns, J.C. and Chamblee, Douglas S. and Daniel, Dorsey W. and Ruiter, J.M. and Fisher, D.S. and Green, J. T. and Mochrie, R. D. and Mueller, J. P. and Pond, K. R. and et al.}, year={1998} }
 @article{burns_chamblee_belesky_fisher_timothy_1998, title={Nitrogen and defoliation management: Effects on yield and nutritive value of flaccidgrass}, volume={90}, DOI={10.2134/agronj1998.00021962009000010016x}, abstractNote={Abstract ‘Carostan’ flaccidgrass ( Pennisetum flaccidum Griseb.), a C 4 perennial grass, has shown high quality potential in animal trials. Its yield response to defoliation frequency and N fertilization, however, has not been reported. We examined the influence of stubble height and of a range of N applications in two defoliation experiments over 4 yr. Experiment 1 (Raleigh, NC) combined two harvest heights, 76 and 38 cm, with two stubble heights, 25 and 15 cm (76–25, 76–15, 38–25, 38–15); all treatments received 380 kg N ha −1 yr −1 . After Year 1, the 76–15 defoliation produced higher yields than 76–25 (Year 2: 11 330 vs. 7930 kg ha −1 , P < 0.001; Year 3:8950 vs. 6270 g kg −1 , P < 0.001), while in vitro dry matter disappearance (IVDMD) was similar (Year 3) (mean = 582 g kg −1 ). Compared with 38–15, the 38–8 defoliation resulted in lower yields (Year 2: 8638 vs. 9344 kg ha −1 , P = 0.001; Year 3, 6173 vs. 8090 kg ha −1 , P = 0.07) but higher IVDMD (Year 3, 651 vs. 635 g kg −1 , P < 0.01). Experiment 2 (Raleigh, NC, and Watkinsville, GA) had four defoliations: clipping to 5 cm at 20 and 51 cm (vegetative) and to 8 cm at boot and anthesis stages (20–5, 51–5, Boot—8, Anthesis—8). All defoliation treatments were topdressed with 291 kg N ha −1 , and 51–5 and Boot—8 were also evaluated with 179 and 403 kg N ha −1 (eight N—defoliation treatments in all). At both locations, highest yields were obtained with Anthesis—8, averaging 19 010 kg ha −1 at Raleigh and 12 390 kg ha −1 at Watkinsville. The 20–5 defoliation resulted in lowest yields at both locations, averaging 7648 kg ha −1 at Raleigh and 5100 kg ha −1 at Watkinsville. Defoliation frequency altered IVDMD (range = 550 to 789 g kg −1 ), but N application did not; however, increasing N application increased N concentrations linearly ( P = 0.05). Flaccidgrass had high yield potential and high nutritive value at the Raleigh location, and warrants further evaluation in the upper South.}, number={1}, journal={Agronomy Journal}, author={Burns, J. C. and Chamblee, D. S. and Belesky, D. P. and Fisher, D. S. and Timothy, D. H.}, year={1998}, pages={85–92} }
 @article{burns_pond_fisher_luginbuhl_1997, title={Changes in forage quality, ingestive mastication, and digesta kinetics resulting from switchgrass maturity}, volume={75}, DOI={10.2527/1997.7551368x}, abstractNote={Five maturities of switchgrass hay harvested at 14-d intervals (vegetative through 20% heading) were fed to Hereford steers (297 kg) in a 5 × 5 Latin square. Relationships with switchgrass maturity were negative and quadratic (P < .05) for DMI and cubic (P < .05) for digestible DMI. Declines in apparent digestibilities of DM, ADF, and cellulose were cubic (P <.05), whereas these were quadratic (P < .05) for NDF, hemicellulose, and CP. Whole masticates from the least, mid, and most mature hays showed linear (P < .05) declines in DM concentration and IVDMD with increasing maturity, whereas NDF concentrations increased linearly (P < .05). Mean retention time of gastrointestinal DM increased linearly (P < .01) from 64 to 94 h from the least to the most mature hay, and the associated rate of passage declined linearly (P < .01) from 3.3 to 2.1%/h. Sieving of masticate DM showed a reduced proportion of large particles (≥ 2.8 mm) and an increased proportion of small particles (≤ .5 mm) with advancing forage maturity. More than 94% of the sieved fecal DM passed a 1.0-mm sieve, but particle sizes showed the same relationship with forage maturity as noted for masticate DM. This occurred despite the comminution from the rumination and digestive processes.}, number={5}, journal={Journal of Animal Science}, author={Burns, J. C. and Pond, K. R. and Fisher, D. S. and Luginbuhl, J.-M.}, year={1997}, pages={1368–1379} }
 @article{buntinx_pond_fisher_burns_1997, title={The utilization of multidimensional scaling to identify forage characteristics associated with preference in sheep}, volume={75}, DOI={10.2527/1997.7561641x}, abstractNote={Forage preference is difficult to assess but is likely an important factor in determining DM intake. In two experiments, six sheep (wethers, Exp. 1; ewes, Exp. 2) were used to obtain preference ratings on nine hays (Exp. 1) or nine fresh forages (Exp. 2). The statistical procedure of multidimensional scaling was used to develop orthogonal dimensions to account for the observed variation in preference for hays and fresh forages. This analysis produced three dimensions that accounted for 54% of the variation in mean 3-d preference for hays (Exp. 1). The three dimensions were subsequently associated by regression analysis with seven compositional variables. These were IVDMD and concentrations of monosaccharides, short-chain polysaccharides (SCP), and disaccharides in dimension 1(R2 = .99); acid detergent insoluble ash (ADIA) concentration, monosaccharide and SCP concentrations, and masticate NDF in dimension 2 (R2 = .99); and disaccharide and starch concentrations in dimension 3 (R2 = .65). Three dimensions accounting for 51% of the variation in fresh forage preference were found and related to four variables by regression analysis. These were disaccharide concentration and median particle size in dimension 1 (R2 = .76) and starch and monosaccharide + disaccharide concentrations in dimension 3 (R2 = .97). No physicochemical variables analyzed in this study were found to be significantly associated with the coordinates for the forages in dimension 2. Multidimensional scaling accounted for more than half the observed variation in animal preference and, in all but one case, these dimensions could be associated with physicochemical characteristics of the forages.}, number={6}, journal={Journal of Animal Science}, author={Buntinx, S. E. and Pond, K. R. and Fisher, D. S. and Burns, J. C.}, year={1997}, pages={1641–1650} }
 @article{fisher_1996, title={Modeling ruminant feed intake with protein, chemostatic, and distention feedbacks}, volume={74}, DOI={10.2527/1996.74123076x}, abstractNote={Little progress has been made in modeling intake regulation in spite of the many mechanisms identified as important. A model with relatively simple inputs was developed that included compartments for protein, soluble carbohydrate, digestible fiber, and very slowly digesting fiber. Distention and chemostatic feedbacks were combined using a previously published equation. The ratio of current ruminal fill to a modulating parameter for ruminal fill represented distention feedback. The ratio of the current flow of available energy to a modulating parameter for chemostatic demand represented chemostatic feedback. The modulating parameter for ruminal fill was based on literature reports of ruminal contents. Intake was adjusted based on current fill and energy flow relative to modulating parameters for fill and chemostatic feedback. The effect of the digestible organic matter (DOM) to CP ratio on DOM intake was modeled to adjust rates of digestion, rates of passage, and the chemostatic feedback. The model tested an integrated concept of intake regulation with only CP, IVDMD, and NDF as inputs. In spite of relatively simple inputs, the model behavior in response to variation in protein, digestibility, and fiber was similar to observations of animal responses.}, number={12}, journal={Journal of Animal Science}, author={Fisher, D. S.}, year={1996}, pages={3076} }
 @article{fisher_baumont_1994, title={MODELING THE RATE AND QUANTITY OF FORAGE INTAKE BY RUMINANTS DURING MEALS}, volume={45}, ISSN={["1873-2267"]}, DOI={10.1016/S0308-521X(94)90279-8}, abstractNote={Abstract The daily forage intake of ruminants is made up of a series of meals. These meals are especially pronounced in animals fed in stalls and coincide with the distribution of food. A relatively simple model of ruminant digestion was developed and used to test equations designed to predict rate of forage intake during meals. An equation that had been published previously as a means of controlling daily dry matter intake was combined with a Michaelis equation to control intake rate as the integrated hunger signal from chemostatic and distension feedbacks varied. The termination of the meal was based on experimental observation and the status of the model was examined for indications of the satiety mechanism at the end of the meal. The predicted level of hunger at the end of the meal varied. It is proposed that the end of the meal is triggered by an integrated hunger and palatability signal and two simple products are suggested by the data; however, the problem is likely to require a more complex function.}, number={1}, journal={AGRICULTURAL SYSTEMS}, author={FISHER, DS and BAUMONT, R}, year={1994}, pages={43–53} }
 @article{fisher_burns_pond_mochrie_timothy_1991, title={Effects of grass species on grazing steers: 1. Diet composition and ingestive mastication}, volume={69}, DOI={10.2527/1991.6931188x}, abstractNote={In traditional grazing trials, per animal and per hectare productivity are determined, but pasture and animal measurements are generally inadequate to address reasons for different treatment responses. This 2-yr study examined the diet and diet characteristics of steers grazing tall fescue (Festuca arundinacea Schreb.), switchgrass (Panicum virgatum L.), flaccidgrass (Pennisetum flaccidum Griseb.), and bermudagrass (Cynodon dactylon [L.] Pers.) pastures. A randomized complete block design was used with two agronomic replicates. In vitro DM disappearance (IVDMD) of masticates from tall fescue (TF), switchgrass (SG), and flaccidgrass (FG) generally were similar; all exceeded 70% (70.3 to 79.9%), except for bermudagrass (BG), which was lowest (63.5 to 65.0%). Sieving the masticate DM showed BG to contain the highest proportion (20 to 29%) of particles passing a .5-mm sieve and the lowest proportion (6 to 8%) of particles retained on a 2.8-mm sieve. This resulted in BG having the smallest mean (1.29 mm) and median (1.08 mm) particle sizes in yr 1 and a mean (1.10 mm) and median (.91 mm) particle size smaller than SG in yr 2. Except for BG, the IVDMD of the masticate DM was lowest for small particles. Canopies showed BG and SG to have the highest proportion of stem (47 and 52%, respectively); the BG canopy was composed of fractions that were consistently lowest in IVDMD. In general, BG offered the grazing animal a canopy inferior in IVDMD concentration and had canopy characteristics that limited the animals' selection of a diet with quality as high as that of TF, SG, or FG.}, number={3}, journal={Journal of Animal Science}, author={Fisher, D. S. and Burns, J. C. and Pond, K. R. and Mochrie, R. D. and Timothy, D. H.}, year={1991}, pages={1188} }