Browsing by Author "Eversole, Dan E."

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    Characterization of estrogen and glucocorticoid receptors, skeletal muscle protein turnover and tissue growth in lambs treated with trenbolone acetate and estradiol
    Frey, Randall Scott (Virginia Tech, 1988-02-15)
    A study was conducted to determine the effects of trenbolone acetate (TBA) and estradiol-17B (E2) implantation on the characteristics of the glucocorticoid and E2 receptor, skeletal muscle protein turnover and tissue growth. Twenty-four lambs were utilized. Trenbolone acetate did not ,affect (P>.10) degradation rates in the semitendinosus (ST) and triceps brachii (TB) muscles, the production of cortisol, adrenal weights and cytosolic glucocorticoid binding capacity (Bmax). Trenbolone acetate decreased synthesis rate of muscle protein (P<.Ol), the percent of [3H] dexamethasone binding in the nuclear fraction, Bmax and the disociation constant (Kd) of the cytosolic E2 receptor, only in the TB muscle. Deoxyribonucleic acid (DNA) of the TB was increased (P<.05) with TBA. Pituitary weights were decreased (P<.005) with TBA and increased (P<.Ol) with E2. Estradiol decreased (P<.05) Bmax of the cytosolic E2 receptor in the ST and decreased (P<.05) Bmax of the nuclear E2 receptor in the TB muscle. The TB muscle had greater (P<.05) synthesis rates than the ST and the protein:RNA ratio was decreased (P<.05) in the TB. The TB muscle had greater (P<.005) Bmax for the cytosolic glucocorticoid receptor.
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    Copper supplementation and monocyte function in growing beef calves
    Saker, Korinn Edna (Virginia Tech, 1995)
    The effect of dietary copper (Cu) supplementation with Cu-Sulfate (CuSO₄) or Cu-Lysine (CuLy) on Cu status and bovine monocyte function was evaluated through a series of experiments. Initially, two in vitro techniques, immunomagnetic (IM) and culture flask adherence (CF), were compared for isolation of a viable, homogeneous monocyte population. The CF technique for monocyte isolation resulted in both a greater number of cells exhibiting phagocytic activity, as well as, an increased phagocytic capacity compared to monocytes recovered by the IM technique. Culture flask adherence appears to be an efficient technique for isolation of a viable, homogeneous population of bovine monocytes. Copper status and monocyte function were evaluated in beef calves supplemented with Cu over a 2 year study period. Fifty-four weaned calves were allotted to one of three Cu treatment groups in a 150 d feeding trial, Plasma Cu concentration was increased in CuLy-supplemented calves over controls and CuSO₄-supplemented calves on d 42, 84, and 126. Calves supplemented with Cu had increased ceruloplasmin activity on d 84, 126, and 150 as compared to controls. Hepatic Cu measured on d 150 was decreased in controls compared to Cu-supplemented calves. Monocyte cell number and function from CuLy-supplemented calves showed increased phagocytosis on d 84 and 126 and increased oxidative burst on d 42 and 126 compared to controls. Dietary Cu supplementation was repeated using 45 calves in a 120 d study. CuLy-supplemented heifers had increased major histocompatibility complex (MHC) class II expression on d 68, 82 and 110 compared to CuSO₄-supplemented and control group heifers. Heifers supplemented with Cu had increased plasma Cu concentrations on d 82 and 110 compared to controls. The effect of vaccination on monocyte function was evaluated in Cu-supplemented beef heifers. Vaccination with B. abortus Strain 19 increased monocyte oxidative burst, phagocytic activity, and MHC class II expression in heifers. Copper supplementation and source of Cu supplement influenced monocyte response to vaccination. Monocyte response appeared to be higher in CuLy-supplemented heifers after vaccination compared to CuSO₄-supplemented and control heifers.
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    Determining the Nutritional Status of Mature Beef Cows
    Horsley, Donald Shane (Virginia Tech, 2002-01-09)
    Improved prediction of forage quality and cow performance may enhance the nutritional management of beef cows. In two 12 mo trials, mature beef cows (n=136) grazing tall fescue pastures were used to compare estimates of forage quality and animal performance. Forage quality was estimated by proximate analysis of forage samples (FOR) or by near infrared reflectance spectroscopy of fecal samples (FNIR). Nutritional Balance Analyzer (NutBal), NutBalPro and 1996 NRC Nutrient Requirements of Beef Cattle (NRC) programs were used to predict animal performance. The objectives were to compare FOR and FNIR estimates of CP and TDN and to evaluate the accuracy of cow performance predicted by FNIR-NutBal, FNIR-NutBalPro and FOR-NRC systems. Initial BW, body condition score (BCS), hip height and breed were used to establish cow biotypes for prediction programs. Every 28 d, cow BW and BCS were measured and forage and fecal samples collected. Weather data, cow status and FOR or FNIR results were entered into NutBal, NutBalPro and NRC programs. Forage CP estimated by FNIR (CPFNIR) or FOR (CPFOR) were similar. In trials 1 and 2, correlation coefficients between CPFNIR and CPFOR were r = .24 and r = .43, respectively. Forage TDN estimated by FNIR was greater (P <.05) and lowly or moderately correlated to FOR estimates. Actual BW change between weigh periods (BWCHG) and ADG were similar to NRC predictions, but less (P<.0001) than predicted by NutBal or NutBalPro. The NutBal or NutBalPro mean BCS change between weigh periods (BCSCHG) were greater (P<.001) than NRC or Actual BCSCHG. Actual and NRC BCSCHG were similar (P>.2, trial 1) or tended (P<.1, trial 2) to be similar. Cow performance estimated by NRC was highly correlated to Actual. Absolute differences in animal performance were also investigated for each prediction program. In trials 1 and 2, NutBal and NutBalPro over-predicted BWCHG, ADG and BCSCHG by 40 kg, 1.25 kg/d and .75 BCS, respectively, compared to actual cow performance. It appears that FNIR is a promising predictor of forage CP but not TDN. Also, the FOR-NRC is a satisfactory predictor of cow performance.
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    Effect of feeding high levels of broiler litter on mineral metabolism and health of beef cows
    Wright, Martha A. (Virginia Tech, 1996)
    Some cattle producers have reported metabolic disturbances in beef cows fed high levels of broiler litter. Therefore, an experiment was conducted to evaluate mineral metabolism of beef cows fed different levels of broiler litter. Sixty Angus-Hereford crossbred cows ranging in age from 3 to 12 yr were blocked by age, BW, and stage of gestation, and randomly allotted within blocks to three diets: 1) mixed hay, full-fed; 2) 4.1 kg of a mixture of 80% broiler litter and 20% cornmeal plus mixed hay (low-litter diet); and 3) 8.2 kg of the 80% litter and 20% cornmeal mixture plus mixed hay (high-litter diet). Cows fed the litter diets were fed 57 g of magnesium oxide per head per day in the litter-corn mixture. Cows fed the three diets had access to a high-Mg mineral mixture. Experimental diets were fed from January 4, 1995 to April 19, 1995, and calving began on March 15. There were no physical signs of metabolic disturbances in any of the cattle. Blood serum Ca decreased and P levels increased in the cows fed both levels of broiler litter after the first 28 d on experiment. On d 28, average serum Ca values were 8.5 mg / dL for the cows fed hay, compared to 7.9 and 7.6 mg / dL for those fed the low and high levels of litter, respectively (P < .01). The average serum P values were 5.7, 8.2, and 9.1 mg/dL, respectively (P < .01). Generally, serum Ca remained lower and serum P remained higher for the cows fed broiler litter until the end of the winter feeding period (105 d). By mid-summer, serum Ca and P were similar (P > .05) for cows that had been fed the three diets. Serum Mg, Cu, and Zn were not affected by feeding litter. Urinary Ca and Mg, expressed as units per unit of creatinine, did not differ (P > .05) among treatments. Serum parathyroid hormone (PTH) was higher (P < .05) in cows fed the lower level of litter than those fed the higher level in April (105 d). Serum PTH values for cows fed hay were intermediate. Birth weights, rate of gain, and weaning weights of calves did not differ among the three diets. Feeding high levels of broiler litter to beef cows appears to affect serum Ca and P.
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    Effects of a sustained-release copper bolus on growth and reproductive traits of beef bulls
    Giustra, Clinton V. (Virginia Tech, 1995-08-15)
    Two experiments were conducted to determine the effects of sustained -release copper (Cu) boluses on growth and reproductive traits of beef bulls. Two groups of bulls were used in consecutive years (n=26 in experiment 1; n=20in experiment 2). Bulls in each experiment were allotted by weight and breed into two equally numbered treatment groups (control (C); treated (T)). Bulls were housed together and offered a balanced diet containing 9 ppm Cu for an ADG of 1.4 kg. Treated bulls in each experiment were given 1 Cu bolus (Cupra,® Pitman-Moore, Mundelein, IL in experiment 1; Copasture â ¢ Copasture- 25 bolus Schering-Plough, Kenilworth, NJ in experiment 2). All bulls were bled, had blood samples taken and had scrotal circumferences (SC) measured on d 0,28,56,84,112, and 140. Blood was collected via jugular venipuncture to determine serum Cu and plasma ceruloplasmin (Cp) concentrations. Breeding soundness examinations (B S E) were conducted on all bulls on d 140 and 185 in experiment 1 and d 168 in experiment 2. Body weight and SC were not affected by treatment in either experiment (P > .05). Serum Cu and plasma Cp concentrations were not affected by treatment in experiment 2 (P > .05). Serum Cu was higher for the T bulls on d 56, 84, and 112 in experiment 1 (P < .05). All serum Cu concentrations for both experiments were within the normal range for cattle. Plasma Cp concentrations were recorded only for d 1, 112, and 140 in experiment 1 and were significantly higher for the C group on d 112 (P < .05). There were no significant effects of treatment on the results of the BSE (SC, percentage of normal sperm, progressive motility, and primary or secondary abnormalities) in either experiment. These data suggest that the Cu bolus in experiment 2 had no effect on body weight gains, SC, serum Cu and plasma Cp concentrations, sperm normality, progressive motility, and primary and secondary abnormalities. These data also suggest that the Cu bolus in experiment 1 had no effect on body weight gains, SC, and sperm normality, progressive motility, and primary and secondary abnormalities; however, treatment in experiment 1 did increase serum Cu concentrations on some but not all days and did not increase concentrations above the normal range for beef cattle. The conclusion made from these experiments is that the sustained Cu boluses used in these studies do not significantly affect growth and reproductive traits in beef bulls with adequate Cu status.
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    Effects of Stress on Several Immune and Health Responses of Weanling Calves
    Shank, Alba Maria Montana (Virginia Tech, 2002-07-02)
    The effects of weaning stressors on several immune and health responses were measured in three experiments. Sixty-four beef calves from 2 sources were bled on d - 7 (pre-weaning), 0 (weaning), 7, 14, and 21 (post-weaning). Serum selenium (Se), neutrophil and lymphocyte counts, and glutathione peroxidase (GSH-Px) activity for erythrocytes and leukocytes were measured for each calf at each date. Erythrocyte GSH-Px activity remained constant over time, while leukocyte GSH-Px and serum Se increased on d 7 (P<0.0001). Effects of single mineral vs. multi-mineral supplementation were measured for several immune and health responses in 2 trials. Trial 1: 36 heifers weaned on-site at SVAREC were randomly assigned 1 of 2 dietary supplements: 1) no supplement; 2) 15% CP at 0.5% BW; and 1 of 3 injection treatments: 1) no treatment (control); 2) Mu-Se injection; 3) Multi-Min injection. Whole blood Se and serum Cu increased post-weaning and serum Zn decreased post-weaning. Mu-Se-supplemented heifers gained weight faster between d 14-28 vs. Multi-Min-supplemented (P=0.01) or control heifers (P=0.02). Trial 2: 48 steers purchased at auction and transported to SVAREC were randomly assigned to 1 of 4 pasture management systems: 1) control (no treatment); 2) litter fed; 3) litter applied; 4) inorganic fertilizer; and 1 of 3 injection treatments (same as Trial 1). Whole blood Se and serum Cu increased post-stress and serum Zn decreased post-stress. Oxidative burst activity decreased in Mu-Se and Multi-min supplemented steers between d 0-4 vs. control steers (P<0.01). Multi-min-supplemented steers had higher phagocytic activity vs. steers in either Mu-Se or control groups (P=0.04).
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    Effects of Vitamin E Supplementation in Late Gestation Cattle and Evaluation of Vitamin E, Cholesterol, and Phospholipid Relationships in Bovine Serum and Serum Lipoproteins
    Bass, Roger Thompson II (Virginia Tech, 1999-04-21)
    The effects of vitamin E supplementation during late gestation were evaluated in dairy or beef cattle in three experiments. Dairy cows were injected with vitamin E and selenium (Se) in one study; beef cows were offered oral vitamin E supplementation via a free-choice vitamin-mineral mix in two studies. Breed-related effects were also evaluated. Jerseys had higher blood Se and lower serum vitamin E concentrations than Holsteins at dry-off and higher blood Se concentrations than Holsteins 3-4 weeks pre-calving and at calving. Selenium supplementation increased blood Se concentrations at calving. Treatment did not affect serum vitamin E concentrations at calving or post-calving, nor blood Se concentrations post-calving. Beef cattle consuming supplemental vitamin E (treatment) had greater responses to treatment when calving in late winter than when calving in late summer. Treated multiparous cows calving in winter had increased serum and colostral vitamin E concentrations but treatment did not affect colostral or serum immunoglobulin G (IgG) concentrations of their calves. Calves from treated, multiparous cows calving in winter had increased 205-day adjusted weaning weights (AWWs). Treatment did not affect colostral vitamin E or IgG concentrations of nulliparous heifers calving in winter, nor serum vitamin E or IgG concentrations, or AWWs of their calves. Six hundred IU supplemental vitamin E/head/day did not affect serum vitamin E concentrations of dams, colostral vitamin E or IgG concentrations, serum vitamin E or IgG concentrations, or growth of calves in the summer-calving herd. Breed-related differences in vitamin E concentrations and AWW occurred in both herds. Consumption of 600-1000 IU vitamin E/cow/day (treatment) during late gestation via a free-choice vitamin-mineral mix increased vitamin E concentrations in serum and the lipoprotein fraction containing no apolipoprotein B (non-ApoB) from 1-2 weeks pre-calving to calving. Treatment group calves had higher vitamin E concentrations in serum and non-ApoB than control group calves. Treatment did not affect cholesterol or phospholipid concentrations in serum or the lipoprotein fractions of either cows or calves. Treatment increased vitamin E cholesterol (VEC) and vitamin E phospholipid (VEPL) ratios in the serum and non-ApoB of cows and calves. Various breed-related differences also occurred.
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    Estimating forage mass of tall fescue pastures and dry matter intake and digestibility of fescue forage by beef steers
    Lopez-Guerrero, Isaias (Virginia Tech, 2005-01-13)
    A series of three experiments were conducted to evaluate different methods of estimating forage mass of tall fescue pastures, and dry matter intake and digestibility in beef steers under indoor and grazing conditions. Forage mass was estimated with the herbage cutting method (HCM) and three indirect methods; the pasture capacitance meter (PCM), the plate meter (PPM), and the visual estimation (VE). The coefficients of determination from the calibration equations were 0.686, 0.751, and 0.862 for the PCM, PPM, and VE, respectively. There were differences in forage mass estimates due to sampling method, sampling date, and their interaction. The second experiment was a digestion trial conducted with confined animals to determine the recovery rate of chromic oxide and alkanes from controlled release capsules and to evaluate the accuracy of the concurrent estimations of intake and digestibility. No difference was found in the recovery rate of either alkanes or chromic oxide during the 7 d of the collection period. Likewise, actual fecal output, dry matter intake, and digestibility were not different from the estimated values. However, estimated values had to be adjusted for the respective recovery rate. The third experiment was conducted under grazing conditions to evaluate the chromic oxide controlled release capsule technique in estimating intake and digestibilty. In this trial, although the recovery rate of the marker was extremely high (avg. = 1.89), the actual and estimated values of dry matter fecal output, intake, and digestibility were not different. Again the recovery rate had to be used as a correction factor.
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    Evaluation of quickstand bermudagrass fertilized with two rates of nitrogen and grazed by sheep at different stocking rates in a temperate environment
    Baker, Scott M. (Virginia Tech, 1993-09-14)
    Two grazing trials and a feedlot trial were conducted with crossbred lambs to evaluate 'Quickstand' bermudagrass (Cynodon dactylon [L.] Pers.) in a cool temperate environment. Four stocking rates and two N fertilization rates (4 x 2 factorial) were replicated three times on .11-ha paddocks. Paddocks were continuously stocked with two, four, six, or eight lambs (light, moderate, heavy, and very heavy stocking rate, respectively) in grazing trial 1. Stocking rates were increased to 4, 8, 12, or 16 lambs per paddock, respectively, in grazing trial 2. In both grazing trials, paddocks were fertilized with 114 (low N) or 340 (high N) kg N ha-1yr-1 in split applications.
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    Evaluation of ruminal escape potential of crab meal and other protein supplements and influence of steam explosion of ruminal degradability of crab meal
    Viswanathan, T. V. (Virginia Tech, 1995)
    Four experiments were conducted, three to study the value of crab meal and other protein supplements, and the other to explore the potential of steam explosion technique to improve the nutritive value of crab meal. In Expt. 1, 48 Angus x Hereford and Angus x Simmental steers (avg. BW, 223 kg) were used in a 126-d growth study. Diets were formulated to contain 10.5% CP and 63% TDN, DM basis. In each diet, one third of the N was supplied by the protein supplement. Steers were randomly allotted to the following six supplements: 1) soybean meal (SBM); 2) supplement based on industrial byproducts of both plant and animal origin (IPA); 3) experimental supplement based on byproducts of animal origin (ESA); 4) hydrolyzed supplement No. 3 (HESA); 5) commercial supplement (Pro-Lak®) based on animal protein (CS) and 6) crab meal (CM). There were no significant positive responses in performance and feed efficiency for any of the protein supplemented groups compared to SBM. There was a trend for a positive response in gain to feed for steers fed CS and IPA. Lower weight gain and gain:feed were recorded for the steers fed HESA supplement. Steers fed CM diet had numerically higher growth and gain:feed than those fed SBM. In Expt. 2, two metabolism trials were conducted, each with 24 wether lambs (avg. BW, 25 kg). In addition to the six diets that were used for the growth trial, two other diets were used, a negative control (NC) with no supplemental N, and a diet supplemented with urea (U). The supplements supplied one third of the total dietary N. There were no differences in DM and OM digestibilities among the lambs fed the different protein supplements. Lower (P < .05) apparent absorption of N was recorded for the lambs fed the HESA and NC diets. There were no differences in ruminal fluid pH among the sheep fed different protein supplements. Sheep fed CM tended to have higher total VFA compared to other supplements. Highest (P < .05) ruminal NH₃ N and blood urea N were observed in lambs fed the U diet. In Expt. 3, the ruminal degradability of DM and CP of crab meal and other protein supplements were estimated in situ, in a ruminally cannulated steer. The highest DM degradability was for SBM. The ruminal escape of protem was lowest (P < .05) for SBM (23.2%) and the highest (P < .05) for the ESA supplement (79.8%). The respective values for IPA, HESA, CS and CM were, 60.6, 67.3, 69.8, and 48.4%. The IVDMD of feather meal and blood meal combinations (ESA and HESA) were lowest (P < .05). The IVDMD of crab meal was 67%. In Expt. 4, the potential of steam explosion technique to enhance the nutritive value of crab meal was explored. Crab meal was steam exploded in a batch steam explosion reactor at two levels of severities. Steam explosion decreased (P < .05) N content of crab meal by 20%, and did not improve DM degradability nor increase escape of CP. A 60% increase in chitin degradability, from 21.5 to 34.2% was observed for steam exploded CM. Steam explosion improved IVDMD of CM from 65.9% to 75.2%. These studies illustrated that substituting other protein supplements used in this study for SBM did not elicit a significant positive response in steer performance. Crab meal is comparable to SBM or other commercial products as a protein supplement for steers. Steam explosion does not seem to be a promising processing method for improving utilization of crab waste for ruminants.
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    Fermentation characteristics and nutritional value of different proportions of alfalfa and wheat straw ensiled with and without different additives
    Rehman, Abdul (Virginia Tech, 1991)
    Experiments were conducted to investigate the fermentation characteristics and nutritional value of mixtures containing different proportions of alfalfa (Medicago sativa L.) and wheat (Triticum aestivum L.) straw ensiled with and without molasses, microbial inoculant and molasses + microbial inoculant. In experiment 1, chopped alfalfa harvested at 1/10 bloom and chopped wheat straw were ensiled in the following proportions (DM basis): 0:100, 25:75, 50:50, 75:25, 100:0, 0:100 (urea-treated), with O and 5% dry molasses, and 0 and .1% microbial inoculant (Lactobaci]lus plantarum and Streptococcus faecium) in a 6 x 2 x 2 completely randomized design with a factorial arrangement. Each mixture was ensiled in 3.8-liter cardboard containers double lined with polyethylene. The pH values for the ensiled mixtures of 0:100, 25:75, 50:50, 75:25 and 100:0 alfalfa:straw without additives were 4.70, 4.76, 4.65, 4.76 and 4.82, respectively. Urea treatment of the 0:100 mixture (wheat straw) increased (P < .01) pH to 8.84. Overall lower pH (P < .01) occurred when molasses was added, compared to untreated and inoculated silages. Lactic acid concentration decreased (P < .01) linearly with decreased level of alfalfa, over all additives. Molasses increased (P < .01) lactic acid concentration. Overall, water soluble carbohydrates (WSC) in pre-ensiled mixtures increased (P < .01) linearly with increases in alfalfa. The WSC decreased (P < .01) after ensiling. Microbial inoculant did not affect pH or lactic acid content in the silages. In vitro dry matter digestibility (IVDMD) increased (P < .01) linearly with level of alfalfa, and molasses increased (P < .01) IVDMD. In experiment 2, chopped alfalfa (1/10 bloom, third cutting) and wheat straw were ensiled in the following respective proportions (DM basis): 0:100, 25:75, 50:50, 75:25, 100:0, 100:0 + 5% dry molasses, and 0:100 (urea-treated) in 210-liter metal drums double lined with .08 mm polyethylene bags. Increased proportions of wheat straw to alfalfa increased (P < .01) DM content and lactic acid concentration, and decreased pH and total VFA content. The CP, Ca, P, Mg and K contents decreased (P < .01) with increases in wheat straw. Addition of molasses to alfalfa increased (P < .01) WSC and lactic acid, and decreased (P < .01) pH and total VFA. Urea treatment of wheat straw increased (P < .01) pH and acetic acid, and decreased (P < .01) lactic acid, compared to untreated wheat straw. The NDF (P < .05) and hemicellulose (P < .01) were decreased with urea treatment. Two metabolism trials were conducted, each with 21 crossbred wethers. The diets were alfalfa and wheat straw silages made in 210-liter metal drums described above. Wheat straw ensiled alone was supplemented with soybean meal because of insufficient consumption when the straw was fed alone. Linear increases (P < .01) in DM, OM, and CP digestibilities were observed with increased level of alfalfa. Adding molasses increased (P < .05) DM digestibility. A linear increase (P < .01) in N retention was observed with increasing alfalfa level. Ruminal NH₃-N and blood urea-N increased (P < .01) with increased proportion of alfalfa. Feeding urea-treated straw increased (P < .01) ruminal NH₃-N and blood urea-N, compared to untreated wheat straw. A palatability trial was conducted with 42 sheep fed the same diets as in the metabolism trials. Daily DM intake increased linearly (P < .01) with increased proportion of alfalfa. It is concluded that ensiling cereal crop residues with leguminous forage has potential in improving fermentation characteristics and nutritional value of alfalfa silage and improving the nutritional value and utilization of cereal crop residues.
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    Influence of endophyte infection of tall fescue with and without white clover on performance, intake, and bite size in steers during the grazing season and subsequent performance in the feedlot
    Tully, James Kevin (Virginia Tech, 1992)
    Experiments were conducted to investigate effects of endophyte (Acremonium coenophialum Morgan-Jones and Gams) infection of tall fescue (Festuca arundinacea Schreb.) on grazing cattle and subsequent feedlot performance, serum minerals and prolactin, intake, digestibility, bite size, and biting rate. Grazing animal performance was measured April to October, 1989 and 1990, at two locations in VA. Effects of grazing low (<5%) and high (>70%) endophyte infected tall fescue, with and without white clover (Trifolium repens L.), were studied with yearling steers. At each location, two replicates were used with a stocking rate of .3 ha/steer (116 steers/yr). At the end of grazing, all animals were finished on a high corn silage diet and slaughtered. Daily gains of steers grazing low endophyte-infected pastures were higher (P<.01) than for those grazing high endophyte-infected pastures. Cattle grazing high endophyte-infected tall fescue with clover at Glade Spring gained at the same rate as those grazing the low endophyte-infected tall fescue without clover during Summer, 1989. During 1990, cattle at Glade Spring had higher (P<.05) daily gains than did those at Blackstone. Rectal temperatures were .5 to 1 °C higher (P<.05) for steers grazing infected pastures by June of each year at both locations. Prolactin concentrations were lower (P<.01) in cattle grazing endophyte-infected fescue within 28 d of initiation of grazing at both locations. Visual evaluation indicated that steers grazing high-endophyte pastures had rough hair coats compared to those grazing low endophyte pastures (P<.01), showing evidence of tall fescue toxicosis. Serum mineral analyses indicated no consistent influence of the endophyte. During feedlot finishing, there were no detrimental effects from previously grazing endophyte-infected tall fescue on animal performance. Forage DM yield, and CP in 1990, and IVDMD in 1989 and 1990 from Glade Spring were higher (P<.05) compared to Blackstone. Forage from Blackstone was typically higher in NDF, ADF, and lignin compared to Glade Spring. Forage from Glade Spring was higher in Ca, Mg, P, and Cu, compared to Blackstone. Diet selection, digestibility, biting size, and biting rate were measured with esophageally-fistulated steers grazing low (<5%) and high (>70%) endophyte-infected tall fescue, with and without white clover. Bite size was smaller (P<.05) in July compared to May, corresponding to decreased quantity of forage available. Bite size and biting rate were not affected by endophyte infection or inclusion of clover. In vitro DM digestibility was higher (P<.05) for high endophyte-infected tall fescue in July. Animals consumed a higher percentage of clover than was available in the sward. Intake and digestibility were estimated using 48 experimental animals and four esophageally-fistulated steers. Chromic oxide sustained-release boluses and forage IVDMD were used to estimate intake. The chromic oxide boluses were determined to be reliable for predicting intake of steers during a 21 d trial involving total fecal collection. Intake was higher (P<.01) in cattle grazing low endophyte-infected tall fescue compared to animals grazing high endophyte-infected fescue. Twenty-one Angus steers (256 kg) were used to compare the effect of 0 and 40% endophyte-infected tall fescue and orchardgrass hay on DM intake, daily gain, body temperature, serum minerals, and prolactin concentrations during an 8 wk study. Quality of the diets was low, as indicated by low CP (8.1 to 10.3%), and IVDMD (41.3 to 47.1%). Daily DM intake and daily gain were higher (P<.05) for animals consuming the noninfected tall fescue compared to animals fed the other hays. Body temperature and serum prolactin were not affected by diet. These data suggest that other factors, besides endophyte infection, are important in the etiology of tall fescue toxicosis. Some of the decreased performance of steers grazing endophyte-infected tall fescue was related to lower intake. Additional research is needed to evaluate higher levels of clover to possibly ameliorate some of the problems of tall fescue toxicosis.
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    Influence of treating corn stover and sorghum forage with different nitrogen sources on nutritive value for ruminants
    Ali, Iftikhar (Virginia Tech, 1991-05-06)
    Experiments were conducted to determine: 1) the fermentation characteristics and in vitro dry matter digestibility (IVDMD) of corn (Zea mays) stover treated with different sources of N; 2) digestibility, N utilization and palatabi1ity in sheep fed corn stover treated with different N sources; and 3) fermentation characteristics and nutrient utilization by sheep of sorghum (Sorghum bicolor L., Moench) forage treated with urea an poultry litter. In a small silo study, corn stover was ensiled untreated or after treatment with 3% aqueous NH₃, 50% and 75% poultry litter, 5.8% urea alone or with 10% cattle waste, 1.5% urease powder or 5% soybeans (Glycine max), DM basis. All treatments resulted in substantial increases (P < .01) in CP of corn stover. Lactic acid was detected in substantial levels only in the stover which was untreated and treated with 50% poultry litter. Ammonia and urea treatments decreased NDF content of stover by 4 to 7 percentage units. Increases (P < .01) of IVDMD of 9 to 14 percentage units resulted from treatment with NH₃ or urea. Use of urease sources did not enhance IVDMD.
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    Nitrogen Utilization and Performance in Ruminants Fed Oscillating Dietary Protein Levels
    Simpson, Sarah Jordan (Virginia Tech, 2000-08-02)
    Nitrogen excreted by ruminants may negatively impact the environment, and N not retained is not utilized for growth and production. Experiments were conducted to examine the effect of 48 h oscillation of two levels of low ruminally degradable dietary CP on N metabolism in lambs and performance of steers. In Exp. 1, a metabolism trial was conducted with 28 lambs (31 kg), allotted to four different diets: 8% CP, 10% CP, 12% CP, and 8% and 12% CP diets oscillated every 48 h. After adaptation, transition, and preliminary periods, feces and urine were collected for 10 d. Ruminal fluid and blood samples were taken at the end of collection and again 2 d later. In Exp. 2, 24 crossbred steers (228 kg) were allotted to four diets: 1) 7.5% CP, 2) 9% CP, 3) 10.5% CP, and 4) 7.5% and 10.5% CP diets oscillated every 48 h. Feed intake was measured during the 112 d study, and ADG and gain to feed ratio were calculated. Cattle were weighed every 14 d and blood samples were taken every 28 d. In Exp. 1, N retention was lowest (P < 0.05) for the lambs fed the 8% CP diet, with no differences among lambs fed the other diets. Differences in urinary N excretion accounted for most of the differences in total N excretion. Ruminal NH3-N and BUN levels were greater in animals fed higher amounts of CP. Ruminal pH and VFA concentrations were not affected by diet. In Exp. 2, feed intake did not differ among steers fed different diets. Average daily gain was lowest for cattle fed the 7.5% CP diet. No significant difference was evident for ADG between steers fed the 7.5/10.5% CP oscillating diet and those fed the 9% or the 10.5% CP diet. Gain to feed ratio was lower (P < 0.05) for steers fed the 7.5% CP diet compared to steers fed all other diets. Blood urea N level was higher for cattle fed the 10.5% CP diet than those fed the two lower CP levels, and differences were usually significant (P < 0.05). No consistent significant difference in BUN levels existed between steers fed the 7.5/10.5% CP oscillating diet and those fed the 9% and 10.5% CP diets continuously. Oscillating two levels of low ruminally degradable dietary CP every 48 h had no significant effect on N retention in lambs nor on the performance of steers compared to animals fed the same level of CP daily in these experiments.
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    Nutritional and hormonal influences on immunoglobulin absorbtion by the preruminant neonate
    Hough, Robert L. (Virginia Polytechnic Institute and State University, 1988)
    Two studies were conducted to investigate factors involved in absorption of immunoglobulins in the preruminant neonate. In the first study 26 Angus cows were fed 57% or 100% of their NRC recommended requirements for protein and energy for the last third of gestation in each of 2 years. Resulting calves were fed measured amounts of colostrum from their dam or from a cow of the reciprocal nutritional treatment group. Cows from the restricted intake treatment lost weight and body condition (P < .05). Gestation length, birth weight, calving ease, days open end weaning weight, however, were not affected by treatment. Calves born to restricted fed dame had higher serum cortisol and lower serum T₃ concentration (P < .05), but absorption of IgG was not affected. Calves fed colostrum from restricted cows did have lower serum IgG concentrations (P < 0.2); although, none of the calves were considered hypogammaglobunemic. In the second study, 2 trials were conducted to evaluate the effect of varying cortisol concentrations on Ig absorption in lambs. Treatments consisted of control (CO), high cortisol (HC), single peak of cortisol (SP) end low cortisol (LC). Lambs in trial 1 were obtained on d 136 to 138 of gestation by caesarean operation. HC and SP lambs tended to have a faster rate of Ig absorption through 24 h, but did not differ from CO lambs in serum Ig concentration by 36 h. Precocious closure to Ig absorption had occurred for LC lambs by 20 h end they had lower Ig concentrations at 36 and 48 h (P < 0.05). In trial 2, lambs were obtained on d 140 to 142 of gestation. Lambs had a shorter Ig absorptive period than trial 1 (24 vs 36 h for CO]. Premature closure for the LC lambs occurred by 16 h postpartum (P < 0.05) and they tended to have depressed Ig concentrations post 24 h.
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    Selenium supplementation and selected immune responses of beef cattle
    Swecker, William S. (Virginia Tech, 1990)
    The effect of selenium (Se) supplementation, by ad libitum salt-mineral mixture (SMM) and/or Se injection, on bovine immune response was evaluated in three experiments. Sixty weaned beef calves, with marginal blood Se (67 μg Se/1), were allotted to one of six Se treatment groups in a 70-day experiment. Antibody responses to lysozyme were lower in calves fed 20 ppm Se salt-mineral mixture (SMM) ad libitum as compared to calves fed 20 ppm Se SMM and injected with 0.1 mg Se + 1.0IU vitamin E/kg body weight, IM, or with calves ad libitum fed 80, 120, 160, or 200 ppm Se SMM. Blood Se on day 70 was higher in calves fed 80, 120, 160, or 200 ppm Se SMM than calves fed 20 ppm Se and injected with 0.1 mg Se + 1.0 IU vitamin E/kg of body weight, IM. An ad libitum 120 ppm Se SMM was compared to Se injection in 80 mid-gestation beef cows that were Se-deficient (50 μg Se/l blood). Supplementation with 120 ppm Se SMM increased blood Se in cows and calves to > 100 μg/l, increased IgG concentrations in colostrum, and increased IgG concentrations in serum of post-suckle calves. Calves from Se-adequate dams had higher Se concentrations in blood and higher average daily gains at 60 days than Se-deficient calves injected with Se at birth. An ad libitum 120 ppm Se SMM was compared to Se injection in 60 Se-deficient (41 μg Se/l blood) weaned beef calves in a 56-day experiment. Calves fed 120 ppm Se SMM and unsupplemented control calves had higher antibody responses to lysozyme than calves injected with 0.1 mg Se + 1.0 IU vitamin E/kg body weight. Blood Se concentrations increased in calves fed 120 ppm Se SMM, did not change in calves injected with 0.1 mg Se/kg body weight, and decreased in control calves. Se treatment did not affect IgA response in tears of calves.
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    Studies on the preservation of crab processing waste and evaluation of the quality of the protein from crab waste
    Joseph, Mercy A. D. (Virginia Tech, 1996-08-05)
    Three experiments were conducted to determine the effect of different chemicals on the preservation of crab waste at room temperature. In Exp. 1, .2 and .4% NaOCI and H₂O₂ were used and the waste was stored for 17 d. In Exp. 2, NaCI (10%), NaNO₂ (1%), NaOCI (.4%), NaN₃ (.065%), KN0₃ (.1%), Tert butyl hydroperoxide (TBHP) (50 ppm), and I₂ (25 ppm) were used. After mixing with the chemicals the waste was stored for 21 d. In Exp. 3, the waste was treated with NaCI (100/0), NaNO₂(10/0) and NaN₃(.065%) and the mixtures were kept for 20, 30 and 40 d. In the first experiment the waste treated with .4% NaOCI preserved better than for the other treatments, with lower (P < .05) NH₃ and trimethylamine (TMA). In Exp. 2, treatment with NaCI, NaNO₂ and NaN₃ did not produce any change in the physical characters of the crab waste. The TMA, indole and NH₃ were lower (P < .05) and no H₂S was detected in the waste treated with those chemicals. In Exp. 3, treatment with NaCI did not alter the physical characteristics of crab waste. The waste had lower (P < .05) NH3, TMA and indole on d 20, 30 and 40 than those treated with NaNO₂ and NaN₃.
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    Utilization of crab processing waste and chitin associated with the waste as feed for ruminants
    Ayangbile, Gbemiga A. (Virginia Polytechnic Institute and State University, 1989)
    Four experiments were conducted with crab processing waste. Addition of 1.5% propionic/formic acid prevented degradation up to 14 d. Desirable fermentation was achieved when 32% of the treated crab waste was ensiled with 32% straw, 16% molasses, and 20% water with or without .1% microbial inoculant. The pH of the silage was lowered and high concentration of lactic acid was observed. Use of .2% NaOCl or .4% H₂O₂ retarded spoilage of crab processing waste up to 7 d. Ensiling of the treated waste (32%), straw (32%), molasses (16%), and H₂0 (20%) indicated that the chemical used in preservation enhanced fermentation. Addition of .4% NaOCl and 1.5% acetic acid to the crab processing waste retarded degradation up to d 4. The trimethylamine (TMA) concentration and NH₃ evolution were highest for the untreated waste while the lowest concentration for TMA and NH₃ evolution were observed for the NaOH-treated waste. Addition of 1% NaNO₂ or combination of .4% NaOCl/CaOCl (1:1, w/w) preserved the waste for up to 10 d. The evolution of NH₃ and H2₂S, and TMA concentration were lowest for the waste treated with 1% NaNO₂. Apparent digestibility of DM, organic matter, CP, energy, NDF, ADF, cellulose and hemicellulose decreased linearly (P<.01) with level of crab waste-straw silage in diets containing 0, 50, and 100% crab waste-straw silage. Nitrogen retention increased linearly (P<.05) with level of crab waste-straw silage. The apparent absorption was higher (P<.01) and retention was positive (P<.05) for Ca, Mg, Na, K, Cu and Fe with sheep fed the highest level of crab waste-straw silage. Daily gain, feed efficiency and carcass characteristics tended to be higher for steers fed 30% crab waste-straw silage, dry basis. The flavor and overall desirability of cooked meat were not adversely affected by feeding up to 30% crab waste-straw silage, dry basis. Modifying the existing methods of quantifying chitin showed that initial decalcification or deprotinization of the samples with chemicals are not necessary. Similar values were obtained for chitin when ADF/ashing method was compared to the ADF/deacetylation method. These methods prevented loss of chitin during preparation. Digestibility of chitin was higher (58%) for sheep fed 100% crab waste-straw silage compared to the value of 37% in sheep fed 50% crab waste-straw silage. When ADF/ashing method was used in quantifying chitin, higher disappearances were obtained for samples containing 100% crab meal kept in the rumen or incubated in vitro for 72 h.