Forage composition and intake by steers grazing vegetative regrowth in low endophyte tall fescue pasture

A grazing trial was conducted with six half-sib yearling Angus steers (average initial weight 281 kg) to quantitate nutrient composition and voluntary intake of vegetative regrowth forage in low-endophyte (Acremonium coenophialum Morgan-Jones and Gams) Kentucky-31 tall fescue (Festuca arundinacea Schreb.) pasture. A new .6-ha section in each of two 3.0-ha pastures (three steers/pasture) was clipped to a 5-cm height on five consecutive days to establish a series of plots that could be grazed continuously during 5-d test periods at uniform stages of vegetative regrowth; each period represented a specific regrowth stage (7, 14, 21, 28 and 35 d). Steers were conditioned by training them to graze to satiety while tethered with an adjustable-length rope to a 1-m galvanized steel post. Grazing time was limited to two sessions daily beginning at 0800 and 1400, and satiety was achieved after no more than 2.5 h of continuous grazing in each session. Forage DM availability was controlled by adjusting tether length and was set each day at 4% of steer BW. Fecal DM output was measured by chromic oxide dilution. A quadratic (P less than .05) effect of regrowth stage was observed for forage contents of NDF and ADF due to abrupt increases in both fractions at wk 5; values for ADL were unaffected by stage of forage regrowth. Forage contents of CP and ash showed a cubic (P less than .05) response to advancing stage of regrowth, with highest (23.6 and 11.0%, respectively) and lowest (14.7 and 9.1%, respectively) values for both fractions occurring at wk 1 and 5, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

内生真菌与高羊茅之间的共生关系

从内生真菌的涵义及其基本生物学特征出发,着重对国内外近10 年来有关内生真菌与高羊茅关系的研究情况作了综述,主要包括内生真菌对高羊茅生长发育及其抗逆性的影响、内生真菌对高羊茅植物群落及生态系统的影响等,并对内生真菌研究的实际意义及其应用前景作了总结。     

Performance, forage utilization, and ergovaline consumption by beef cows grazing endophyte fungus-infected tall fescue, endophyte fungus-free tall fescue, or orchardgrass pastures.

Two 120-d trials (May to September, 1988 and 1989) determined the effects of grazing tall fescue (two varieties) or orchardgrass on forage intake and performance by beef cows. Each summer, 48 cow-calf pairs grazed endophyte-infected Kentucky-31 tall fescue (KY-31), endophyte-free Mozark tall fescue (MOZARK), or Hallmark orchardgrass (OG) pastures (16 pairs/treatment). Forage OM intakes and digestibilities were determined during June and August each year. Cow and calf BW and milk production were determined every 28 d. During June of both years, OM intakes did not differ (P greater than .10) among treatments. During August of 1988, intakes were 18% lower (P less than .05) by KY-31 cows (1.6% of BW) than by MOZARK or OG cows (average 1.95% of BW); however, no differences (P greater than .10) were measured in August of 1989. Estimates of ergovaline consumption during June from KY-31 were between 4.2 (1988) and 6.0 mg/d (1989), whereas August estimates were between 1.1 (1988) and 2.8 mg/d (1989). Ergovaline in MOZARK estrusa was below detection limits, except in August of 1989. Cows that grazed KY-31 lost three times (P less than .01) more BW than cows that grazed MOZARK or OG (42 vs 9 and 13 kg, respectively). Milk production by KY-31 cows was 25% lower (P less than .01) than that by cows that grazed MOZARK or OG (6.0 vs average of 8.0 kg/d). Similarly, slower (P less than .01) calf gains were noted for KY-31 than for MOZARK or OG (.72 vs .89 and .88 kg/d, respectively). Cows grazing KY-31 experienced accelerated BW loss and reduced milk production and weaned lighter calves than did cows grazing MOZARK or OG. Decreased performance was not explained by consistently reduced forage intakes; hence, altered nutrient utilization was suspected.     

内生真菌对苇状羊茅和多年生黑麦草影响的研究进展

综述了内生真菌的分类及其在宿主苇状羊茅Festuca arundinacea和多年生黑麦草Lolium perenne中的分布与传播方式,阐述了内生真菌对苇状羊茅和多年生黑麦草生长、抗生物(病虫害)和非生物胁迫(P胁迫和干旱胁迫等)、以及对其他草类的竞争他感作用的影响,并提出今后的研究方向.     

Energy and protected protein supplements to lambs on endophyte-infected tall fescue pasture

The effect of supplements on intake, digestibility, N retention, ADG and blood and body composition of growing lambs fed cut herbage or grazing KY 31 tall fescue (Festuca arundinacea Schreb.) pastures at two levels of N fertilization (92 and 318 kg/ha) was determined. Supplements were corn (C), corn with soybean meal (U-SBM) and corn with heat-treated SBM (H-SBM). Metabolism trials were run at three growth stages in the 1st yr with 24 lambs. Although all supplements increased total DMI and DM digestibility, they decreased NDF digestibility relative to grass (G), with no difference between supplements; C depressed apparent CP digestibility. Nitrogen retention increased from -2.5 g/d on G to -.4 g/d on C and 3.2 and 4.1 g/d on U-SBM and H-SBM, respectively, for combined periods and N rates. Blood urea N (BUN) concentrations differed (P less than .01) in the following order: G greater than U-SBM greater than H-SBM greater than C. In the 2nd yr, lambs (n = 64) grazed fescue pastures at the same N fertilizer rates and were given the same supplements. Gains were not different (P less than .05) on low-N (LN) and high-N (HN) pastures. Seasonal ADG were 80, 115, 122 and 130 g/d for G, C, U-SBM and H-SBM treatments, respectively, with no difference (P less than .05) between U-SBM and H-SBM. At slaughter, lambs from G had lower dressing percentages (P less than .05) and fat content (P less than .01) than lambs on C, U-SBM and H-SBM treatments, with no differences between supplements. Results indicated a better performance of growing lambs on fescue with both energy and protein supplements. Response to protected vs unprotected protein was small.     

Productivity of cow-calf pairs grazing tall fescue pastures infected with either the wild-type endophyte or a nonergot alkaloid-producing endophyte strain, AR542

The nonergot alkaloid-producing endo-phyte, AR542, has been shown to improve the persistence and yield of tall fescue pastures without causing the animal disorders commonly associated with tall fescue toxicosis. A 3-yr grazing study was conducted to compare effects of AR542-infected tall fescue pastures with wild type endophyte-infected (E+) tall fescue pastures on cow-calf performance. Replicated 7.3-ha pastures of each treatment were grazed by cow-calf pairs (16 pairs per pasture replication) each year from March to weaning in September. The cows were exposed to breeding on their respective pasture treatments from April 1 through June 15. The treatment groups were compared for reproductive performance, ADG, BCS, calf growth rate, and weaning weight. Blood samples were also collected for serum prolactin (PRL) analysis. There were no significant differences in calving rate (P = 0.98) or calving interval (P = 0.62) between pasture treatments. Cows that grazed the AR542 pastures subsequently gave birth to calves that were heavier (P < 0.05) than calves from cows that had grazed the E+ pastures. Cows grazing the AR542 pastures had higher (P < 0.05) BCS at the end of the grazing period, and had higher ADG during the grazing period. Calves raised on the AR542 pasture had higher (P < 0.05) ADG and weaning weights than calves of the same sex raised on the E+ pastures. Serum PRL concentrations were decreased (P < 0.05) in both cows and calves on the E+ pastures compared with serum PRL concentrations in cows and calves grazing the AR542 pastures. The results indicate that grazing tall fescue pastures infected with the AR542 endophyte may give significant advantages in cow-calf growth rates and BCS over grazing E+ pastures. However, there did not seem to be any benefit in reproductive performance in this trial. There was a small, but significant increase in birth weight in cows grazing AR542 pasture.     

过渡气候带高羊茅草坪的建植和养护管理

介绍了高羊茅Festuca arundinacea草坪草的品种选择、建植方法、梅雨季节和高温季节的养护,重点叙述了高羊茅草坪的修剪、肥水管理、病虫草害防治、生物调节剂应用等内容.     

Hemodynamic responses of the caudal artery to toxic tall fescue in beef heifers

Color Doppler ultrasonography was used to compare blood flow characteristics in the caudal artery of heifers fed diets with endophyte (Neotyphodium coenophialum) infected (E+) or noninfected (E-) tall fescue seed. Eighteen crossbred (Angus x Brangus) heifers were assigned to 6 pens and were fed chopped alfalfa hay for 5 d and chopped alfalfa hay plus a concentrate that contained E-tall fescue seed for 9 d during an adjustment period. An 11-d experimental period followed, with animals in 3 pens fed chopped alfalfa hay plus a concentrate with E+ seed and those in the other 3 pens fed chopped hay plus concentrate with E E- seed. Color Doppler ultrasound measurements (caudal artery area, peak systolic velocity, end diastolic velocity, mean velocity, heart rate, stroke volume, and flow rate) and serum prolactin were monitored during the adjustment (baseline measures) and during the experimental period. Three baseline measures were collected on d 3, 5, and 6 during the adjustment period for comparison to post E+ seed exposure. Statistical analyses compared the proportionate differences between baseline and response at 4, 28, 52, 76, 100, 172, and 268 h from initial feeding of E+ seed. Serum prolactin concentrations on both diets were lower (P <0.001) than baseline beginning at 4 h from the start of the experimental period. However, trends in serum prolactin concentrations for heifers on the E- diet suggested ambient temperature was affecting these concentrations. Caudal artery area in E+ heifers had declined (P <0.10) from baseline by 4 h and was consistently lower (P <0.05) for the remainder of the period. Heart rates for E+ heifers were lower than the baseline rate from 4 (P <0.10) to 100 (P <0.001) h, but were similar (P >0.10) to the baseline for 172 and 268 h measures. Blood flow in E+ heifers was consistently lower than the baseline from 4 (P <0.05) to 172 (P <0.001) h, but was similar to the baseline at 268 h when heart rate was similar to the baseline rate. Caudal artery areas for the E- diet were similar to baseline areas except at 100 h when it was greater than baseline. Heart rates and flow rates for E- heifers did not differ (P >0.10) from baseline measures during the experimental period. Results indicated that onset of toxicosis was within 4 h of cattle exposure to E+ tall fescue and is related to vasoconstriction and reduction in heart rate.     

Physiological responses of cattle consuming tall fescue to environmental temperature and supplemental phenothiazine

The influence of supplemental phenothiazine (P) on growth and physiological criteria was studied in parasite-controlled calves consuming endophyte (Acremonium coenophialum)-infected tall fescue (TF). In Exp. 1, nine Angus heifer calves (312 kg) were supplemented with 227 g corn-mineral (CM) mix twice daily and allowed ad libitum access to either high-endophyte (HE) G1-307 (greater than 90% infected) or low-endophyte (LE) Kenhy (less than 1% infected) tall fescue hay, or HE G1-307 plus 2 g/d P in the daily supplement. Calves were kept in temperature-controlled rooms for 12 d at 21 degrees C followed by 7 d at 34 degrees C. In Exp. 2, 48 Angus steer calves (312 kg) were assigned to treatment groups consisting of calves grazing HE Kentucky-31 (57% infected) or LE Johnstone (less than 1% infected) TF, and supplemented daily with either .91 kg of a control CM mix or .91 kg of the CM mix containing 2 g P. The 112-d experiment was initiated on May 4 with BW and rectal temperature (RT) measurements and blood collected at 28-d intervals. In both experiments, calves receiving HE TF had lower (P less than .01) serum prolactin concentrations (PRL) at elevated ambient temperature and lower (P less than .01) serum alkaline phosphatase activities (AP) but higher (P less than .01) RT than calves consuming LE TF regardless of ambient temperature.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of a ruminally dosed tall fescue seed extract as a model for fescue toxicosis in steers

Tall fescue (Lolium arundinaceum) toxicosis research is often complicated by a reduction in intake of infected forage or seed, making treatment comparisons difficult. This study was conducted to develop a fescue toxicosis model that would allow for variations in DMI without altering the quantity of alkaloids consumed over the course of the experiment. Ground tall fescue seed and a tall fescue seed extract were used in two 2-period crossover experiments to determine the effectiveness of ruminal dosing of a tall fescue seed extract to induce fescue toxicosis. This experiment used 4 growing Holstein steers (BW = 337 ± 24 kg) surgically fitted with ruminal cannulas. Steers were maintained on a diet of endophyte-free fescue hay fed ad libitum throughout the experiment. Endophyte-infected (E+; 4.1 mg/kg of ergovaline) and uninfected (E-; 0.0 mg/kg of ergovaline) KY-31 tall fescue seed was ground and dosed or extracted with ethanol, concentrated, and lyophilized before ruminal dosing. Ergovaline concentration of the final extract was 102 mg/kg. Animals were given a minimum of a 3-wk washout period between treatments. Physiological indicators were measured over 7 d at 22°C (d 1 to 3) and 32°C (d 4 to 7) during both seed and extract dosing. Seed and extract E+ dosing reduced serum prolactin concentrations such that they were not different from zero (P < 0.10). Treatment with E+ reduced feed intake (P < 0.05) and heart rate (P < 0.001), and increased respiration rate (P < 0.01) and core temperature (P < 0.05) during both seed and extract dosing. Increasing environmental temperature from 22 to 32°C reduced total intake (P < 0.05) and increased core temperature (P < 0.001) and respiration rate (P < 0.001) during both seed and extract dosing. Diastolic blood pressure tended (P < 0.09) to be increased during E+ extract dosing and reduced during heat stress. These physiological alterations are consistent with those reported for cattle grazing or consuming seed from endophyte-infected tall fescue. These data indicate that a ruminally dosed ethanol extract of tall fescue seed is efficacious in inducing fescue toxicosis in cattle.     

高羊茅草坪的建植与管养技术

1　草坪的作用及高羊茅草坪的优点[1] 　　　绿色代表着生命 ,也是文明程度的显著标志 ,草坪是绿色的重要组成部分 ,它不仅能吸收大量的ＣＯ2 、释放出更多的Ｏ2 、清新净化空气 ,而且还能减少尘埃、降低噪音、吸收有害气体、局部调节大气温度和湿度、吸收强烈日光对眼睛的伤害 ,因此 ,草坪在城市环境保护和环境质量提高方面起着十分重要的作用。草坪覆盖面积是评价现代化城市建设的重要标准之一 ,将城市地面除道路、建筑物外尽可能地用草坪覆盖起来是现代化城市建设的重要内容。随着两个文明建设的不断发展 ,芜湖市人民不仅要求三季有花而…     

Growth rate and physiology of steers grazing tall fescue inoculated with novel endophytes

Cattle grazing tall fescue (Festuca arundinacea Schreb.) often develop fescue toxicosis. This condition is thought to be caused by ergot alkaloids produced by the endophyte Neotyphodium coenophialum. Endophytes from wild tall fescue plants, which do not produce ergot alkaloids, were transferred into the endophyte-free tall fescue germplasm, HiMag. The novel associations also lacked the ability to produce ergot alkaloids. Our objective was to determine whether cattle grazing these novel endophyte associations showed signs of fescue toxicosis. At the Fayetteville, Arkansas location, tester steers (n = 72) were assigned to one of four pasture treatments: endophyte-free HiMag tall fescue (HiMag-); 'Kentucky-31' tall fescue infected with its native, toxic endophyte (KY+); and two novel endophyte-infected tall fescue associations, HiMag4 and HiMag9. At the Mount Vernon, Missouri location, steers (n = 54) were used to test three of the four cultivars (HiMag9 was not tested). Ergot alkaloid concentrations in the forage of HiMag4 and HiMag9 were low or undetectable. Respiration rate, rectal temperature, ADG, and hair scores were measured during the grazing period. Blood was collected via jugular venipuncture and used for prolactin, aspartate aminotransferase, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), cholesterol, triglyceride, and creatinine analysis. Weight gains by steers grazing HiMag4 and HiMag9 did not differ from those of steers grazing HiMag-, but were greater than gains (P < 0.05) by steers on the KY+ treatment. Steers grazing KY+ had higher (P < 0.05) respiration rates, rectal temperatures, and hair scores than did steers grazing novel endophyte and HiMag- pastures. Prolactin, ALP, cholesterol, LDH, and triglycerides all were suppressed (P < 0.05) in steers grazing KY+ compared with steers grazing novel endophyte and HiMag- pastures. Steers grazing the novel endophyte tall fescues did not suffer from the decreased weight gains and toxicities associated with fescue toxicosis, resulting in enhanced animal production.     

Effect of endophyte type on carcass traits, meat quality, and fatty acid composition of beef cattle grazing tall fescue

Fourteen Hereford steers were used to compare carcass traits, meat quality, and fatty acid composition of beef from cattle grazing tall fescue infected with either wild-type (E+; n = 6) or novel, nil ergot alkaloid (AR542; n = 8) endophyte for 209 d. Average daily gain, live weight, and HCW were greater (P < 0.05) for AR542 cattle than for E+. No differences in LM color or pH were observed between AR542 and E+. Steaks from E+ cattle tended (P = 0.10) to have higher L* and b* than those from AR542 cattle at 0 d of display. Ground beef from E+ cattle also had higher (P < 0.05) L* than AR542 cattle, with no differences in a* or b* at 0 d of display. Color changes during display did not differ for both steaks and ground beef from E+ and AR542. Lipid oxidation levels increased (P < 0.05) during simulated retail display, but they did not differ between endophyte treatments. Adipose tissues from E+ cattle had a higher (P < 0.05) percentage of SFA, and a lower (P < 0.05) percentage of MUFA than adipose from AR542 cattle. Ground beef and i.m. fat had higher (P < 0.05) concentrations of SFA, MUFA, and cis-9, trans-11 isomer of conjugated linoleic acid, and lower (P < 0.05) concentrations of PUFA and PUFA:SFA ratio than s.c. fat. The n-6:n-3 fatty acid ratio did not differ among fat depots. Ergot-alkaloids were detected in s.c. adipose tissues, and alkaloid concentration was greater (P < 0.05) for E+ than AR542. Warner-Bratzler shear force values did not differ between endophyte types, but it decreased (P < 0.01) across the postmortem aging period. Conversely, sensory panel evaluation detected greater (P < 0.01) chewiness and lower (P < 0.05) juiciness for AR542 than for E+ steaks aged for 14 d. Although grazing cattle on tall fescue pastures infected with nil ergot alkaloid endophyte improved cattle performance, these results suggest that endophyte type has minor effects on carcass traits and meat quality of pasture-fed beef. Moreover, finishing cattle on tall fescue pastures showed the potential to enhance the fatty acid profile of beef from a human health perspective. Alkaloid concentration was greater (P < 0.05) in s.c. fat from E+ than AR542 (2.81 vs. 0.92 ppb; fresh-tissue basis). This is the first published report demonstrating the presence of alkaloids in beef tissues.     

Animal performance and economic comparison of novel and toxic endophyte tall fescues to cool-season annuals

Increased costs of annual establishment of small grain pasture associated with fuel, machinery, and labor are eroding the profitability of stocker cattle enterprises. Interest has therefore increased in development of cool-season perennial grasses that are persistent and high quality. This study occurred on 24 ha (divided into thirty 0.81-ha paddocks) located at the University of Arkansas Division of Agriculture Livestock and Forestry Branch Station, near Batesville. Two tall fescue (Festuca arundinacea Schreb.) cultivars infected with novel endophytes (NE), Jesup infected with AR542 endophyte (Jesup AR542), and HiMag infected with Number 11 endophyte (HM11) were established in September 2002. Jesup AR542 and HM11 were compared with endemic endophyte Kentucky 31 (KY-31) tall fescue; wheat (Triticum aestivum L.) and cereal rye (WR, Secale cereale L.) planted in September 2003, 2004, and 2005; and annual ryegrass [RG, Lolium perenne L. ssp. multiflorum (Lam.) Husnot] planted in September 2004 and 2005. Each year, 3 steers (3.7 steers/ha) were placed on each pasture for fall and winter grazing, and 5 steers (6.2 steers/ha) were placed on each pasture for spring grazing. Animal performance is presented by year in the presence of a year x treatment interaction (P < 0.01). Body weight gain per hectare of steers grazing NE tall fescue was greater (P < 0.01) than those of KY-31 and WR during 2003 to 2004, whereas in 2004 to 2005, BW gain per hectare of steers grazing NE and RG did not differ (P < or = 0.29) and was greater (P < 0.01) than that of WR, which was greater (P < 0.01) than that of KY-31. During 2005 to 2006, BW gain per hectare was greater (P < 0.01) for steers grazing RG than those of NE and WR, which did not differ (P > or = 0.14). Body weight gain per hectare was least (P < 0.01) for steers grazing KY-31. Average net return of NE tall fescue was greater (P < 0.01) than KY-31, but profitability of NE did not consistently differ from cool-season annuals. Across the 3-yr study, NE tall fescue produced net returns per hectare of $219; this level of profitability would require 4 yr for a new planting of NE tall fescue to break even. Novel endophyte tall fescues offer potential benefits related to decreased risk of stand establishment of annual forage crops, longer growing season, and acceptable animal performance.     

Technical note: sampling technique and drying method effects on chemical composition of tall fescue or fescue-ladino clover pasture samples

Although esophageal extrusa is the most readily accepted representation of forage consumed by grazing ruminants, esophageal sampling is demanding from the standpoint of animal care and maintenance and extrusa processing. This experiment was conducted with a split-plot design to evaluate the effects of pasture type, pasture sampling technique and drying method on estimation of grazed forage composition. Ten esophageally fistulated steers grazed pastures of either tall fescue (Festuca arundinacea Schreb.) or tall fescue interseeded with ladino clover (Trifolium repens L.); steers were closely observed during four collection periods to determine their exact grazing location. Forage samples were collected either directly from the esophageal fistula (E) or hand-gathered (HG) from the immediate perimeter of the grazed area. Samples of E and HG from each steer were divided and oven-dried at 40 degrees C or lyophilized. Fescue samples had lower (P less than .01) N and ADF N concentrations than fescue-ladino clover samples, and E-collected fescue samples had lower (P less than .05) in vitro digestible OM than E-collected fescue-ladino clover samples. Sampling x drying method interactions were detected (P less than .01) for OM, NDF, ADF, hemicellulose (HEMI), ADL, alkaline peroxide lignin (APL), ADFN and indigestible ADF (IADF). Oven-dried E had higher (P less than .05) NDF, ADF, HEMI, ADL, APL and ADF N than lyophilized E; ADF N and IADF were higher from oven-dried HG than from lyophilized HG. In vitro digestible OM was not modified by oven drying. Hand-gathered samples, whether lyophilized or oven-dried, did not simulate E dried by lyophilization. Standardized collection techniques and drying procedures should be implemented to minimize damage to fibrous components.     

Growth and reproductive performance of beef heifers grazing endophyte-free, endophyte-infected and novel endophyte-infected tall fescue

A three-year study was conducted to investigate the effects of endophyte-free (E−), endophyte-infected (E+) and novel endophyte-infected (EN) tall fescue on the growth and pregnancy rate of beef heifers during the spring. Each year, 48 beef heifers were strip-grazed on stockpiled fescue from December through February, fed fescue hay during late February to early April and then rotationally grazed on spring growth of fescue until June. At the end of the trial, heifers had been maintained on E+, E− or EN (pasture or hay) for a total of 152, 188 and 191 d in years 1, 2, and 3, respectively. In late March, heifers were synchronized using a controlled intravaginal drug-releasing device, (CIDR®) for 7 d followed by injection with PGF2α (Lutalyse®). Heatmount detectors (Kamar®) and observation for behavioral estrus were used to detect estrus for 63 d. Heifers were artificially inseminated 8 to12 h after the onset of standing estrus. Conception was determined by transrectal ultrasonography at approximately 30, 60 and 90 d after synchronization. Reproductive performance did not differ among treatments (P ≥ 0.20). Pregnancy rate was 54, 65, and 65% for E+, E− and EN, respectively. However, during the spring, growth and prolactin were decreased (P < 0.01) for heifers on E+. Gains on spring pasture were 0.24, 0.75, and 0.71 kg/d (SEM ± 0.03) for E+, E− and EN, respectively. Based on these results, the wild type endophyte-infected fescue can be used in production systems as a source of winter forage but producers should consider placing heifers on alternative forage (such as the novel endophyte-infected fescue) in the spring.     

Selenium supplementation improves nutrient intake and digestibility,and mitigates CH4 emissions from sheep grazed on the mixed pasture of alfalfa and tall fescue

Low selenium (Se) in soil and forage can adversely affect on the quality of animal-derived foods, and hence on human health. Lambs grazed on mixed pastures of alfalfa (Medicago sativa) and tall fescue (Festuca arundinacea) were supplemented with five levels of Se [0, 3, 6, 9 and 12 µg/kg body weight (BW)]. The intake of dry matter (DM) and organic matter (OM) varied with the level of Se supplementation, with a peak at 6 µg Se per kg BW (p ≤ 0.05). Gross energy (GE) intake, digestive energy (DE) intake and metabolic energy (ME) intake were higher at 6 µg Se per kg BW than at other Se levels (p < 0.01); in addition, methane energy (CH₄-E) output was lower at 6 µg Se per kg BW. Supplementation with Se significantly increased nitrogen (N) intake, faecal N and urine N, for which the peak values were 20.2 g N/, 5.62 g N/day and 7.92 g N/day, respectively, at 6 µg Se per kg BW. Se intake, blood Se, faecal Se, urine Se and retained Se were negatively correlated with forage crude protein (CP) content (p < 0.001) but were positively correlated with the content of neutral detergent fibre (NDF) (p < 0.001) and acid detergent fibre (ADF) (p < 0.001). Thus, we recommend the addition of 6 µg Se per kg BW to sheep grazed on pastures in regions with low soil Se.     

Metabolic and endocrine responses of lambs fed Acremonium coenophialum-infected or noninfected tall fescue hay at equivalent nutrient intake

Ten Hampshire x Western wether lambs (means weight = 30.1 kg) equipped with ruminal and abomasal cannulas were fed either low-Acremonium coenophialum (AC) Kentucky-31 (less than 1% infected) or high-AC G1-307 (greater than 95% infected) varieties of tall-fescue (TF) hay of similar nutrient composition in a completely randomized design. Lambs were housed in metabolism crates at 21 +/- 1 degrees C and fed 552 g DM/d of ground hay at 0800 and 2000. A 10-d adaptation preceded 7 d of sample collection. Levels of water and DM voluntarily consumed by the low-AC group during the adjustment period were held constant for both treatment groups throughout the collection period by intraruminal insertion of unconsumed DM and water. Fixed water intake markedly reduced voluntary water intake but it alleviated previous depressions in voluntary DM intake in lambs fed high-AC. Mean daily respiration and heart rates, rectal temperature and hematocrit were not affected (P greater than .10) by treatment. Compared with high-AC, lambs fed low-AC retained a greater (P less than .10) amount of N (1.8 vs 1.1 g/d) and a greater (P less than .10) percentage of their N intake (16.4 vs 9.9%). Abomasal total and bacterial N flow and ruminal digestion of cell wall components were not affected (P greater than .10) by treatment. Total tract digestion of DM, NDF and ADF was lower (P less than .01) for high- than for low-AC. Serum prolactin concentration was higher (P less than .10) for lambs fed low- than for those fed high-AC TF, but serum cortisol and thyroxine concentrations were not affected (P greater than .10) by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

高羊茅和狗牙根草坪草品种在重庆地区的引种试验

引自百绿集团的6个草坪草品种,在重庆地区进行2年的坪用性状评价。结果表明,供试品种在该地区均可终年生长。5个高羊茅品种中以Vegas表现最好,叶色浓绿,生长速度适中,盖度居供试品种之首,对该区高温高湿和高温干旱2个越夏因子均可适应;其次为Barlexas。狗牙根BarCd8USAI耐高温干旱,抗病性强,茎细叶窄,但叶色偏淡,冬季停止生长早,早春生长速度缓慢。     

贵州高羊茅新品种(系)比较试验

2007-2010年对选育鉴定的高羊茅(Festuca arundinacea)新品系,按照完全随机区组排列设计方法,进行品种比较试验.结果表明,在株高30～40 cm时刈割测产,大方高羊茅每年的鲜草产量和干物质产量都比对照Fawn高许多,其中第2年的鲜草产量和干物质产量分别为87 825和15 360 kg/hm2,...