Browsing by Author "Gerken, Hubert J. Jr."
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- Breeding Gilt Project RecordGerken, Hubert J. Jr. (Virginia Cooperative Extension Service, 1973-06)Who Uses This Project Record? You must complete this record if you are enrolled in the 4-H Breeding Gilt Project. After your gilt has had her first litter, you may enrolI in the 4-H Feeder Pig Project. On the other hand, you may, if you wish, obtain another gilt and continue with the 4-H Breeding Gilt Project. You should have a copy of Publication 562, 4-H Swine Breeding Guide. To obtain a copy, contact your project leader or Extension Agent.
- Control of endometrial secretion in cattle and production of transgenic swineWilliams, Barry L. (Virginia Tech, 1991)Endometrial tissue was collected from cows to determine effects of day of the estrous cycle, location of the ovulatory structure and progesterone (P₄) on endometrial protein secretion. Day 0 (estrus) endometrial tissue released more protein than tissue collected on d 9, 14 or 18. Protein synthesis was greater on d 0 and 18 than d 9 and 14. Endometrium from the uterine horn contralateral to the ovulatory structure synthesized more protein than endometrium ipsilateral to the ovulatory structure. Seventeen protein bands were identified by electrophoresis. Proximity of the ovulatory structure to the uterine horn affected the presence of four proteins. Quantitative release of seven proteins was influenced by day of the estrous cycle and uterine horn. Day of the estrous cycle and location of the ovulatory structure alter endometrial protein secretion and synthetic activity and have effects on individual proteins. A second project utilized 116 gilts and sows to evaluate estrous synchronization/superovulation schemes. Pronuclear microinjection and zygote culture in excised mouse oviducts also was assessed. Synchronization/superovulation procedures were: 1) sows observed for estrous behavior (NAT), 2) cyclic gilts synchronized with altrenogest (ALT) for 15 to 19 d and superovulated with pregnant mares serum gonadotropin (PMSG) and human chronic gonadotropin (hCG; LALT), 3) gilts between 11 and 16 d of the estrous cycle receiving ALT for 5 to 9 d and superovulated (SALT), and 4) precocious ovulation induced with PMSG and hCG (PRE). Zygotes from PRE donors received microinjection of buffer, DNA or no microinjection. Ova were cultured in modified Krebs Ringer Bicarbonate medium (KRB) or mouse oviduct (MO) explants. SALT and PRE had higher ovulation rates than LALT (24.7 ± 2.9, 24.3 ± 1.8 vs 11.6 ± 2.7; x̄ ±SEM). DNA microinjection resulted in a lower (P<.05) cleavage index (CI) than buffer injection or no microinjection (2.16 ± .10 vs 2.80 ± .13 and 2.93 ± .10). MO improved (P<.01) CI over KRB. MO culture for 72 h was the most beneficial system (P<.05; CI 3.25 ± .12). Cl of 2.66 ± .18, 2.79 ± .14 and 2.40 ± .14 were observed from MO for 48, 96 and 120 h, respectively. Transfer of 505 DNA microinjected zygotes into 17 recipients produced seven litters and 50 piglets of which eight were transgenic. Microinjection of DNA, not merely the mechanical procedure, was detrimental to embryo development and culture for 72 h in MO provided optimal CI.
- Crop residue feeds for beef cattleGerken, Hubert J. Jr.; Eller, Arthur L. Jr.; Smith, Easley S.; White, Harlan E. (Virginia Cooperative Extension, 1992)Discusses various crop residue that can be used as low-cost feeds for beef cattle.
- Effect of application of fluidized bed combustion residue to reclaimed mine pastures on forage yield, composition, animal performance and mineral statusSmedley, Kristi Olson (Virginia Polytechnic Institute and State University, 1985)Reclaimed surface mined soils in Appalachia are typically infertile and must be amended for optimum vegetative growth. Fluidized bed combustion residue (FBCR), a by-product of coal-fired power plants, has high levels of Ca, S, Zn, Fe, and Al, and 50% of the neutralizing capacity of limestone. Three treatments were applied to three replicated .81 ha reclaimed mine pastures: control (no amendment), 6760 kg FBCR/ha, and 3380 kg limestone/ha. Based on forage availability, six steers were rotationally grazed on pastures receiving each treatment. Steers were weighed and blood samples collected at 14-d intervals and all animals were sacrificed for tissue sampling at the end of the 114-d trial. Amendment with FBCR or limestone increased soil pH (P < .05) above control levels. Forage yield and steer gain were not significantly affected by treatment. Forage samples collected during the trial indicated that FBCR and limestone amendments elevated forage ash, Ca, Mg, S, Cu and Ca:P ratio (P < .05). Cellulose and NDF were depressed in forage grab samples collected from FBCR- and limestone-amended pastures. The forage sampled the following spring was lower in hemicellulose, Zn, un and Ni; and higher in ash, Ca, S, the Ca: P ratio in the FBCR- and limestone-amended pastures. Mean serum mineral levels of steers were not affected by pasture treatment. The blood packed cell volume was higher in cattle grazing FBCR-amended pastures. Liver levels of Fe, H, Hi and Na were lower in cattle on pastures amended with FBCR or limestone. Bile levels of Mn were depressed in cattle grazing FBCR~ and limestone-amended pastures. The level of Cu in the liver and serum was at deficiency levels and was not detectable in bile, regardless of treatment. Higher kidney levels of Ca, Hg and P were recorded for steers grazing FBCR- and limestone-amended pastures. Hair Zn was higher in cattle grazing the FBCR- and limestone- treated pastures. Rib Cr and long bone Cd levels were lower in animals grazing the limestone- and FBCR-treated pastures. This study suggests that FBCR amendment enhances nutrient quality of forage and mineral status of animals at least as well as limestone application to acidic reclaimed mine pastures.
- Effect of feeding high levels of broiler litter on mineral metabolism and health of beef cowsWright, 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.
- Effect of land application of fluidized-bed combustion residue on soil and plant characteristics of reclaimed surface-mined pastures, performance and mineral status of grazing steers and nutrient balance by sheep fed the forageCochran, Michele A. (Virginia Tech, 1988-02-15)Fluidized-bed combustion residue (FBCR) results from mixing coal with limestone during the combustion process. This by-product may be used as a liming agent. A grazing trial was conducted on an acidic mine soil to compare FBCR to dolomitic limestone and no amendment (control). Six steers per treatment were grazed rotationally on three replications (rep) of three .8 ha pastures. Both materials increased soil pH similarly, and reduced plant uptake of Fe, Zn, Mn, and Ni similarly. Calcium concentration increased in forages by both amendments, Mg increased with limestone and S with FBCR application. Cell wall components decreased, while ash and lignin increased with both amendments. Serum mineral levels of cattle were normal except Cu was low. Animal tissues reflected differences in mineral concentration observed in forages. Hay harvested from one rep was used in a mineral balance trial with 18 wethers. Apparent digestibility of dry matter, crude protein and fiber components, and N retention were not affected by treatment. Control animals were in negative Ca balance. Apparent absorption of Mg was higher (P < .01) for limestone treatment animals; S absorption was higher for the FBCR group; and, Zn absorption was higher for controls. Serum mineral levels of sheep were normal except Cu was low. No appreciable accumulation of heavy metals occurred in forage or animal tissues. Low Cu levels observed for all treatment groups indicate a problem inherent of the study site. FBCR appears to be a safe and efficient soil pH amendment.
- Effect of monensin supplementation on ruminal and postruminal digestion in sheep and on adaptation of ruminal microbesRogers, Michaela G. (Virginia Polytechnic Institute and State University, 1987)Three experiments were conducted to examine the effects of an ionophore, monensin sodium, on digestion in sheep. The first experiment was concerning alterations induced by long-term supplementation and subsequent withdrawal of the ionophore. The diet was a pelleted mixture of 43% native prairie hay, 34% corn grain, and 21% lupin grain plus 100 g wheat straw. Monensin (33 ppm) was added to the diet of four wethers, and four other animals served as controls and consumed an identical diet. without monensin. Monensin supplementation increased (P <.05) ruminal propionate while decreasing (P <.05) acetate levels throughout the 146-d experiment. Withdrawal caused acetate to return to control levels but decreased (P <.05) propionate. During ionophore supplementation, the digestibilities of organic matter (OM) and dry matter (DM) were increased (P <.05) by an average of 8 and 9%, respectively. Apparent digestibility ' of N was increased from 75 to 77% after 19 d of supplementation. There was an augmentation (P <.05) in the flow of bacterial N at the duodenum after 96 d of supplementation. This effect disappeared with ionophore withdrawal. In a second experiment, the effect of monensin on postruminal digestion was examined in three trials with six wethers. There were three treatments: control, dietary monensin, and monensin infused into the duodenum. The diets were the same as in the previous experiment. Dietary monensin caused the same changes in ruminal VFA as in the previous experiment. Infused monensin had no effect on VFA. Dietary monensin increased (P <.05) trypsin activity at the ileum. Dietary ionophore did not alter nutrient digestibilities, but shifted (P <.O5) the site of OM and DM digestion from the cecum to before the terminal ileum by 14 and 10%, respectively. In an in vitro experiment rumen contents from monensin-adapted and nonadapted sheep were compared with and without additional ionophore in a 6 h incubation system. Rumen contents from adapted sheep did not differ from contents of nonadapted sheep in the quantity of microbial N synthesized. With monensin addition to the incubation, microbial synthesis dropped by 49% in nonadapted microorganisms. In adapted contents, the decrease in synthesis was only 9%. Monensin-adapted microbes degraded (P <.O1) more protein substrate than those which were not adapted.
- The effect of stage of maturity on the biological availability of magnesuim from wheat and orchardgrass fed to sheepStager, Cynthia Lee (Virginia Tech, 1976-12-05)Wheat, a tetany prone forage, and orchardgrass, a non-tetany prone forage, were cut at three stages of maturity to determine the magnesium availability in these forages for lambs. The forages were dried in forced air ovens and ground through a 2.5 cm screen. The nitrogen contents of the forages were not significantly different between forages but decreased quadratically with maturity in wheat (P < .Ol) and linearly in orchardgrass (P < .Ol). Nonprotein nitrogen was significantly higher in wheat than in orchardgrass. The magnesium content of the wheat was lower (P < .O1) than orchardgrass (.14 vs .21%). Magnesium content in wheat was similar at all maturities but decreased with maturity in orchardgrass. Potassium, calcium and phosphorous levels in the forages were similar between wheat and orchardgrass but decreased with advancing maturity in both forages. In two metabolism trials with 18 wether lambs, the biological availability of magnesium was determined for the two forages cut at three stages of maturity. The biological availability of magnesium for lambs fed wheat was slightly lower than for those fed orchardgrass. It increased linearly with increasing maturity in wheat (P < .O1) and tended to decrease with maturity in orchardgrass. In the first two maturities of wheat, the biological availability of magnesium was approximately 22% and for the third maturity it approached 39%. In orchardgrass, it was 36, 34 and 28% for maturities l, 2 and 3, respectively.
- Effect of treating corn stover with aqueous ammonia and urea on nutritional valueObamehinti, Johnson Muftau (Virginia Tech, 1987-03-05)Experiments were conducted to study the effect of treatment of rectangular bales of corn stover with aqueous ammonia and urea solutions. The stacks were covered with polyethylene sheets for 129 d, after which they were uncovered, aerated and sampled for laboratory analyses.
- Effects of feeding lasalocid and monensin upon mineral status of steers, and partial absorption and renal handling of minerals in sheepKirk, David J. (Virginia Polytechnic Institute and State University, 1989)Studies were conducted to determine the effects of feeding lasalocid and monensin upon mineral status of ruminants, changes in digestive and renal physiology which bring about altered mineral status, and the effects of dietary K upon the actions of ionophores. Two 84-d grazing trials were conducted with steers fed no ionophore, 200 mg lasalocid, or 150 mg monensin. Monensin tended to increase gain of steers, but lasalocid had no effect. Feeding supplemental lasalocid and monensin altered Ca, P, Mg, Na, K, Cu, Fe and Zn status of grazing steers, but effects were not consistent. Twenty-four crossbred steers were individually fed in a 147-d finishing trial to study a possible K x monensin interaction. Steers were fed diets ad libitum containing .4% or 2.3% K, with or without 23 ppm monensin, dry basis. Feeding monensin with low K increased serum Na, Mg, inorganic P, Cu and Zn, but monensin fed with high K had no effect or decreased these serum minerals. Fifteen wethers, fitted with abomasal and ileal cannulae, were fed a basal diet alone or supplemented with 23 ppm lasalocid or monensin; Apparent absorption of Mg, K and Fe increased when ionophores were fed. Magnesium flow through the small and large intestines was decreased by lasalocid and monensin. Effects of lasalocid and monensin differed for metabolism, digestive tract flow and (or) partial absorption of Ca, P, Cu, Fe and Zn. Twelve ewe lambs were used in a renal clearance experiment. Lambs were fed a basal diet with no ionophore, 23 ppm lasalocid, or 23 ppm monensin, dry basis. Ionophores were fed starting on d 1 of the experimental period. Serial collections of blood and urine were made during d 1 and d 5 of the experimental period. Monensin reduced urine flow rate at d 1 and d 5. Feeding monensin lowered serum clearance and urinary excretion rates of Na and K at d 5. Serum clearance and urinary excretion rates of Ca were lower in sheep fed ionophores at d 1. Feeding monensin decreased serum clearance and urinary excretion rates of Cu at d 1. At d 5, urinary excretion rates of Zn were greater when lasalocid was fed, and lower when monensin was fed, compared to feeding no ionophore. These studies indicate that dietary lasalocid and monensin can alter mineral status of ruminants, although their effects may differ. The effects of ionophores may be dependent upon dietary K levels.
- Evaluation of quickstand bermudagrass fertilized with two rates of nitrogen and grazed by sheep at different stocking rates in a temperate environmentBaker, 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.
- Evaluation of ruminal escape potential of crab meal and other protein supplements and influence of steam explosion of ruminal degradability of crab mealViswanathan, 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.
- Feeder Pig Project RecordGerken, Hubert J. Jr. (Virginia Cooperative Extension Service, 1973-06)Who Uses This Project Record All members enrolled in the 4-H Feeder Pig Projectmust complete this record. It is designed for use by the club member with two or more sows and perhaps a boar and other breeding stock. This project can be as large as facilities and interest will permit. Beginners and club members with one gilt or sow should enroll in the 4-H Breeding Gilt Project. Each member taking this project should obtain a copy of Publication 562, 4-H Swine Breeding Guide. To get your copy, contact your 4-H project leader or Extension Agent.
- Feeding broiler litter to beef cattle and sheepGerken, Hubert J. Jr. (Virginia Cooperative Extension, 1992)Informs cattle and sheep producers on the correct use of broiler litter in rations prepared on the farm.
- Fermentation characteristics and nutritional value of different proportions of alfalfa and wheat straw ensiled with and without different additivesRehman, 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.
- Fermentation characteristics, nutritional value and palatability of ensiled seafood wastes and low quality roughagesSamuels, Winston Anthony (Virginia Polytechnic Institute and State University, 1983)Fish and crab processing wastes were ground and ensiled with corn stover or peanut hulls alone and with 5% dry molasses or 1% formic acid in 3.8 liter cardboard containers double lined with polyethylene. The wastes and roughages were ensiled in proportion to give dry matter levels of 40, 50 and 60%. The seafood wastes were also ensiled with wilted Johnsongrass with and without molasses. After ensiling, average pH for mixtures with fish waste was 6.5, compared to 8.0 for mixtures with crab waste. Addition of dry molasses resulted in a decrease (P <.01) of pH to 5.6 for the ensiled fish mixture but had no effect on the crab waste mixtures. Lactic acid was higher (P< .01) for ensiled mixtures containing fish waste than for those containing crab waste. Substantial levels of acetic acid were present in the silages. Butyric acid levels were higher in silages containing crab waste and decreased linearly (P< .01) with increased dry matter levels. Desirable ensiling was observed for the mixture of fish waste and Johnsongrass. Coliforms and fecal coliforms were decreased or elIminated by ensiling. In a large silo study, mixtures of finfish and crab processing wastes were mixed with wheat straw and ensiled in 210 liter metal drums, double lined with polyethylene bags. Proportions of the fish and straw were 70:30 and 51:49, wet basis, while that of the crab was 60:40 and 40:60. Acetic acid was added to the crab waste mixtures to lower the initial pH to 4.5. After ensiling all mixtures containing fish and straw showed a decrease in pH. Addition of acetic acid to mixtures containing crab waste inhibited fermentation, but resulted in a very stable product. In a sheep digestion trial, dry matter digestibility was higher (P <.01) for the 70:30 diet than for the 51:49 fish diet. There was no difference in dry matter digestibility between the crab silages. Crude protein digestibility was higher (P <.01) for diets containing ensiled fish, compared to diets containing ensiled crab. Nitrogen retention was positive for sheep receiving all diets. Nitrogen retention was higher (P <.01) for animals fed the crab silage diets, compared to those receiving diets containing fish silage. There was a trend for P absorption to be higher in animals fed crab silage. In the sheep palatability trial, intake of dry matter was higher (P < .01) for sheep consuming the crab silage diet and lowest (P <.01) for sheep fed the 70:30 fish silage diet.
- Heritability estimates for calving date in Simmental cattleMeacham, Nancy S. (Virginia Tech, 1987-05-15)Variation among sires in daughters' reproductive performance was analyzed using data on 4,360 cows from nine herds obtained from the American Simmental Association. Cows were required to have at least 50% Simmental breeding, to have calved first at 2 yr of age and to have been born and subsequently calved in the same herd and season. Traits analyzed included first and second calving dates, first calving interval and the percentage of cows that returned to calve in the same season as 3-yr-olds. Data were adjusted for effects of percentage Simmental and first-calf calving ease score. At second calving, purebred Simmentals calved 1.7 ± 1.2 d later than 75% Simmental cattle and 5.1 ± 1.4 d later than 50% Simmental cattle. When compared to cows that calved without assistance at first calving, cows experiencing easy pulls were 1.7 ± 1.4% less likely to calve as 3-yr-olds and had 4.9 ± 1.0 d longer calving intervals. Cows with hard pulls were 9.0 ± 2.1% less likely to return and had 6.5 ± 1.6 d longer calving intervals. Cows requiring Cesarean section were 23.1± 2.5% less likely to return and had 19.6 ± 2.4 d longer calving intervals. Heritability estimates were .17 ± .04 for first calving date, .07 ± .06 for second calving date, .04:105 for calving interval and .11 ± .04 for percent return. Calving interval does not appear to be a useful selection criterion to improve reproduction. Phenotypic and genetic correlations of first calving date with calving interval were -.58 and -.83 ± .37, respectively. The genetic correlation between first and second calving dates was .66 ± .41. Given current data recording procedures, calving date appears to be the most useful potential selection criterion to improve reproductive fitness.
- Impact of lignification of corn stover fractions on cell wall degradation by rumen microorganisms and response to ammonia treatmentSewalt, Vincent Johannes Hendrikus (Virginia Tech, 1993)Changes in cell wall composition and in vitro degradation of corn stover fractions (leaf, upper stem and lower stem) with advancing maturity and in response to NH; treatment were determined, and possible inhibitory mechanisms of lignin were evaluated. With advancing maturity, IVDMD decreased (P<.001), associated with decreases (P<.001) in CP and water soluble carbohydrates (WSC), and increases (P<.001) in NDF and ADF. The IVDMD of leaf was higher (P<.001) than of stems, associated with higher CP, hemicellulose:cellulose, and arabinan:xylan, and lower lignin methoxyl content. A hypothesis of formation of reactive quinone methide intermediates from lignin during rumen fermentation was tested in vitro by incubating corn stover fractions with S-containing reducing agents. Sulphur incorporation into residual fiber occurred (P<.05), indicative of nucleophilic addition to quinone methide intermediates. Degradation of NDF was highly correlated with lignin methoxyl content. The impact of lignin on cellulose degradation was studied using lignocellulosic hydrogels, in which hydroxypropylated or unmodified hardwood lignin was blended with cellulose. In vitro cellulose degradation of lignocellulose blends was higher (P<.01) than of control. Addition of lignin at incubation depressed (P<.01) cellulose degradation. Hydroxypropylation enhanced (P<.001) the increase in cellulose degradation with lignin blending, and reduced (P<.001) the inhibitory effect of lignin addition at incubation. Treatment of drought-stressed corn stover with 3% aqueous NH₃ decreased (P<.05) NDF, compared to isonitrogenous NH₃ addition and control, associated with solubilization of hemicellulose. Esterified phenolic acids were released (P<.05) by NH₃ treatment in upper stem. The IVDMD and NDF degradation increased (P <.001) after ammoniation, with higher (P<.05) values for NH₃ treatment than NH₃ added in leaf. The in vitro response to ammoniation of fractions of drought-stressed and non-drought stressed corn stover harvested in subsequent years was compared, using N-sufficient and N-limiting buffers. Response was highest (P<.001) for non-drought stressed stover fractions, and in N-limiting medium. Response appeared to be affected by high concentration of WSC in lower stalks of drought-stressed stover.
- 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 feedlotTully, 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.
- Influence of grazing sheep and cattle together and separately on soils, plants and animalsAbaye, Azenegashe Ozzie (Virginia Tech, 1992-02-25)Angus cows (Bos taurus) with calves and 1/2 Dorset, 1/4 Finn and 1/4 Rambouillet ewes (Ovis aries) with lambs grazed Kentucky bluegrass (Poa pratensis) - white clover (Trifolium repens) in a randomized block design with three replications during 3 yr, to investigate effects of grazing cattle and sheep together and separately on soils, plants and animals. Additionally, changes in stocking rate, seasonal distribution of cool-season forages and varying nutritional requirements of animals were examined. There were 6 cow-calf pairs or 6 ewes with 11 lambs per replication of cattle alone and sheep alone treatments. Six cows plus six ewes, with their offspring, were allotted to each replication of mixed grazed pastures. Initial stocking rates were equilibrated among treatments to 1 cow and calf per .45 ha. Grazing sheep alone increased (P < .05) percentage bluegrass (58%) but decreased white clover (6%) and weeds (36%), compared to pastures grazed only by cattle (30, 16 and 53%, respectively, which was similar to initial composition). Soils in mixed grazed pastures remained higher (P < .05) in plant nutrients, pH, and percent organic matter and were less (P < .05) compacted, compared to soils where sheep or cattle grazed alone. Total forage mass and quality were higher (P < .05) in mixed grazed pastures, compared to pastures grazed by cattle and sheep alone. Daily gain (.23 kg/d), total gain (23 kg), and weaning weights (43 kg) of lambs were higher (P < .01) in pastures grazed by both animal species, compared to sheep alone (.18 kg/d, 19 and 38 kg, respectively). These animals also reached target weaning weights (43 kg) 14 d earlier (P < .05) than those grazed alone. Body condition of ewes was improved by the breeding season, compared to ewes grazed alone. Five measuring techniques were investigated to determine forage mass and botanical composition. Measurements based on small plots permanently located within pastures were as accurate as those based on the entire pasture. Visual estimations of forage mass were lower, compared to hand clipping, but reflected canopy height. Visual evaluations more accurately estimated presence of individual plant species than hand separated samples. Grazing ewes and cows with associated spring-born offspring on bluegrass-white clover improved the balance between plant growth and animal forage requirements and improved sustainability of the soil-plant-animal system.