Browsing by Author "Wahlberg, Mark L."

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    4-H livestock advancement project guide and record
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2003)
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    4-H Livestock Advancement Project Guide and Record
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2001)
    Project guide and record to help 4-H members learn about the livestock industry.
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    4-H livestock record book : beef-swine-sheep
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2000)
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    4-H Livestock Record Book: Beef-Swine-Sheep
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2004)
    This record is designed for youth in their first years of livestock project work.
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    4-H market beef planning guide
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2000)
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    4-H Market Beef Planning Guide
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2004)
    This planning guide provides the information needed to estimate the finished weight of a feeder calf.
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    Advanced 4-H livestock record book : beef-swine-sheep
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2003)
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    Advanced 4-H livestock record book : beef-swine-sheep
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2005)
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    Advanced 4-H livestock record book : beef-swine-sheep
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2000)
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    Alternative Feeds for Beef Cattle
    Wahlberg, Mark L. (Virginia Cooperative Extension, 2005-09-01)
    Contains descriptions of many of the alternative and by-product feeds available in Virginia, and how they may be used in beef production systems.
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    Beef : a hand-y food
    Stadler, Kathleen M.; Essa, Jumanah S.; Wahlberg, Mark L. (Virginia Cooperative Extension, 2001)
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    Cattle acclimate more substantially to repeated handling when confined individually in a pen than when assessed as a group
    Parham, Jamie T.; Tanner, Amy E.; Blevins, Sarah R.; Wahlberg, Mark L.; Lewis, Ronald M. (Oxford University Press, 2022-03-01)
    Chute (CS) and exit (ES) scores are common subjective methods used to evaluate temperament in cattle production systems. A pen test, which allows behavior to be observed in a non-restrained setting, may also be an effective method to evaluate temperament by allowing more variation among animals to be expressed. The merit of pen scores in assisting producers in evaluating temperament is equivocal. The objectives of this study were to validate the usefulness of a pen score in delineating temperamental cattle and to determine whether these behavioral scores change under repeated and routine management. Over 3 consecutive years, a factorial design of two measurement protocols (frequent [F], infrequent [IN]) and three recording periods was used. The F measurements were collected over 3 consecutive days and IN measurements only on day 1 within a recording period. Each year, 20 mostly Angus commercial Bos taurus heifers were randomly assigned to each protocol. Behavior was measured using a CS, ES, and exit velocity. Body temperature and heart rate also were recorded. A fecal and blood sample were collected and analyzed for levels of various metabolites including glucose concentration and serum cortisol. Following routine handling, each heifers' response to 30 s of exposure to a human stressor was recorded both individually and in groups of four. An individual (IPS) and group (GPS) pen scores were assigned from 1 (docile) to 6 (aggressive). For all heifers, protocol, event, and their interaction, were compared on the first day of an event. For F heifers, event and day within event were instead used. Body weight was included as a covariate, with sire and year fitted as random effects. Reliability of IPS and GPS were determined using a kappa (K) coefficient. Both IPS and GPS were reliably assigned (K = 0.64 and 0.44 for IPS and GPS, respectively) and positively correlated with body temperature, heart rate, glucose, and serum cortisol (r = 0.28 to 0.37). Furthermore, F heifers acclimated to repeated handling in an individual pen setting (P < 0.05) while acclimation to handling within groups was not evident (P > 0.14). IPS provides a reliable evaluation of temperament in a non-restrained setting that is indicative of an animal's response to stress and may be useful when attempting to make phenotypic selection decisions. However, temperamental heifers became calmer with repeated gentle handling. Pen scores collected on heifers either individually or as a group can be reliably assigned and are indicative of an animal's response to stress during normal handling practices. Lay Summary Chute and exit scores are common subjective methods used to evaluate temperament in cattle production systems. A pen test, which allows behavior to be observed in a non-restrained setting, may also be an effective method to evaluate temperament by allowing more variation among animals to be expressed. However, the merit of pen scores in assisting producers in evaluating temperament has yet to be discerned. Therefore, the objectives of this study were to validate the usefulness of pen scores in delineating temperamental cattle and to determine whether these behavioral scores change under repeated and routine management. Pen scores collected on heifers either individually or as a group could be assigned reliably and were indicative of an animal's response to stress during normal handling practices. Temperamental heifers, when handled more frequently, acclimated to repeated handling in an individual pen setting but not in a group. Therefore, regardless of method, when cattle are excitable during their first handling experience, more than one observation of temperament may be beneficial before assessing temperament.
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    Characterization of seasonal reproduction in Virginia Tech Selection Line, St. Croix, and Suffolk ewes
    Jordan, Katherine Mead (Virginia Tech, 2008-08-04)
    This dissertation research contained three studies. The first two studies were conducted to investigate the ability of ewes to rebreed while lactating during seasonal anestrus. Breeds studied included the Virginia Tech Out-of-season (OOS) Line, which is a wool line genetically selected to lamb in the fall, and the St. Croix, a hair breed of tropical origin thought to be lowly seasonal. When January-lambing ewes were exposed to rams while lactating in April, significantly more OOS than St. Croix ewes were marked by rams in the first 21 d and total 39 d of ram exposure (58.3 vs. 8.7%, P = 0.0003 and 95.8 vs. 43.5%, P < 0.0001). Percentages of ewes diagnosed pregnant (53.2%) and percentages of ewes lambing (41.3%) were not different between breeds. When March-lambing OOS ewes were exposed to rams while lactating in May, 52.9% of ewes were marked though only 20% of ewes exposed to rams gave birth to viable lambs. Both OOS and St. Croix ewes appear to be well suited to accelerated production systems involving 7 to 8 mo lambing intervals. However, reduction of lambing intervals to 6 to 7 mo appeared to have detrimental effects on fetal survival in OOS ewes. In a third study, alterations in endocrine profiles associated with differing degrees of hypothalamic sensitivity to estradiol-negative feedback and changing daylength in OOS, St. Croix, and Suffolk ewes in the absence of rams were investigated for 1 yr. The results show for the first time that based on progesterone profiles from intact ewes, St. Croix ewes do not have shorter anestrous periods than ewes of wool breeds, as previously thought. Based on luteinizing hormone profiles from ovariectomized ewes treated with estradiol implants, the duration of luteinizing hormone inhibition was shorter in OOS than Suffolk ewes (68 vs. 170.2 d, P = 0.02), but was not different from that found in St. Croix ewes (124.8 d). Specific roles for thyroxine and prolactin in timing the breeding season could not be assigned. This study was the first known use of the ovariectomized, estradiol-implanted ewe model to compare degree of reproductive seasonality in different breeds.
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    Cloverbuds cook with Pyramid Chef. Lesson 5: Eating a variety of beef foods and raising beef cows in Virginia
    Stadler, Kathleen M.; Essa, Jumanah S.; Wahlberg, Mark L. (Virginia Cooperative Extension, 2001)
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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 Different Protein and Energy Supplements on Performance and Health of Beef Calves During the Backgrounding Period
    Austin, Robert Jesse (Virginia Tech, 2001-08-15)
    Newly received or weaned calves are highly susceptible to the incidence of bovine respiratory disease. In addition to high levels of stress, decreased feed intake and exposure to foreign antigens result in increased morbidity and possibly death losses. Four backgrounding trials were conducted to examine the effects of protein and energy supplements to stressed calves consuming different forages. Body weights, rectal temperatures and blood samples were taken on d 0, 7, 14, 28 and 42. Supplements consisted of corn or mixtures of corn and soybean meal. In trial 1, 48 heifers (average BW = 219 kg) fed fescue hay in drylot, were allotted to four treatments: no supplement, 15% CP supplement (0.5% BW), 15% CP supplement (1.0% BW) and 30% CP supplement (0.5% BW). Supplemented heifers had higher (P<0.05) ADG than unsupplemented heifers by 42 d. Heifers fed the 30% CP supplement had higher (P<0.05) plasma urea-N by d 42. In trial 2 (pasture study 1), 36 steers (average BW = 217 kg) grazed stockpiled tall fescue and were allotted to three treatments: no supplement, a 15% CP supplement (0.5% BW), and a 15% CP supplement (1.0% BW). After wk 1, ADG was lower (P<0.05) for supplemented calves. At the end of the trial, steers supplemented at 0.5% BW had higher (P<0.05) ADG than steers supplemented at 1.0% BW. Glutathione peroxidase levels were lower (P<0.05) for supplemented steers on d 28. For trial 3 (pasture study 2), 48 steers (average BW = 202 kg) grazed stockpiled tall fescue and were allotted to three treatments: no supplement, corn (1% BW), and 15% CP supplement (1% BW). After wk 1, ADG was higher (P<0.05) for steers supplemented with corn. Steers supplemented with 15% CP supplement had the lowest (P<0.05) ADG after 7 d. At d 42, supplemented steers gained faster (P<0.05) than unsupplemented steers. For trial 4 (pasture study 3), 48 steers (average BW = 202 kg) grazed stockpiled tall fescue or fescue-alfalfa and were allotted to two treatments: no supplement and a 15% CP supplement (0.5% BW). During wk 1, steers grazing fescue had higher (P<0.05) ADG than steers grazing fescue-alfalfa. During wk 1, supplemented steers had a higher (P<0.05) morbidity scores. At d 42, ADG was higher (P<0.05) for supplemented steers. No consistent differences were detected in forage and blood serum mineral concentrations in all trials. Glutathione peroxidase activity increased (P<0.05) for all trials on d 14, regardless of supplementation. Supplementation improved ADG by d 42 but did not affect overall health status of calves in all trials.
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    Effect of Form and Amount of Phosphorus and Phytase Supplementation on Phosphorus Utilization by Ruminants
    Shanklin, Rachel Kristina (Virginia Tech, 2001-07-11)
    The use of animal manures to replace commercial fertilizer has increased the economic and environmental sustainability of agriculture. However, this practice has resulted in excess P being applied to the soil in some areas. Excess P may run-off into surface water and leach in the ground, causing eutrophication. Decreasing the amount of P fed and improving the utilization of P are two possible nutritional solutions to this problem. Two experiments were conducted to investigate the effects of levels of dietary P, chemical form of P, and phytase supplementation in ruminants. For Exp. 1, 24 steers (average BW = 229 kg) were allotted to two diets containing 0.12 and 0.19% dietary P for a 112-d growth trial. The steers were individually full-fed, weighed every 14 d, and blood samples were collected every 28 d. The steers fed the 0.12% P diet had increased (P<0.02) ADG during the first 28 d, after which there were no differences. They also had higher (P<0.05) feed intake. By d 56 serum P for the 0.12% P group was lower (P<0.01), and this difference continued for the remainder of the trial. For Exp. 2, 18 wether lambs (average BW = 23 kg) were allotted to the following six diets for each of two metabolism trials: 1) a negative control diet deficient in P, 2) control diet supplemented with inorganic P, 3) control diet supplemented with phytic acid, 4) control diet supplemented with phytic acid and phytase, 5) control diet supplemented with cottonseed meal, and 6) control diet supplemented with cottonseed meal and phytase. Each metabolism trial was preceded by a 5 wk depletion phase in which the lambs were fed a low-P diet. The metabolism trials consisted of a 10 d preliminary period followed by a 10-d collection of feces and urine. On the final day ruminal fluid, blood, and saliva were collected. At the end of the second metabolism trial 10th rib bones were collected from each lamb. Absorption of P was lowest (P<0.0001) for the low-P treatment, compared to the other treatments. There was no treatment effect on saliva P. Ruminal fluid P was higher (P<0.05) for lambs receiving P supplementation. Within supplementation treatments, ruminal fluid P was higher (P<0.05) for lambs fed organic P than for those fed inorganic P. Feeding CSM resulted in higher (P<0.001) ruminal fluid P than phytic acid. The addition of phytase to the diets with organic P resulted in more (P<0.04) P in the ruminal fluid. There was a decrease (P<0.003) in serum P associated with the low-P treatment. There was no difference in bone ash or breaking strength.
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    The effect of supplementation strategy, stress level, and tall fescue type on performance of fall-weaned beef calves
    Pickworth, Carrie Lynn (Virginia Tech, 2005-06-20)
    The beef cattle marketing structure imposes stress on calves due to weaning, transport, commingling, and adaptation to new diets, resulting in a weakened immune systems at the height of disease risk, frequently causing bovine respiratory disease. Backgrounding programs facilitate opportunities for calves to overcome stressors by building immunity, and adapting the rumen to high concentrate diets for improved feedlot performance. Four experiments were conducted to compare backgrounding strategies and effects of supplementation frequency performance and the effects of the ruminal environment. In Exp. 1, 48 weaned steers were used to investigate the effects of transportation and supplementation frequency, while in Exp. 2, 36 heifers were used to investigate only supplementation frequency. No differences in gains were observed due to transportation stress or supplementation frequency. Weaning stress resulted in elevated (P < 0.05) creatine kinase and neutrophil:lymphocyte ratios during the first week. In Exp. 3, 48 calves were used to compare the effect of tall fescue type on performance and health. Calves on novel endophyte fescue had higher ADG (P = 0.07) than on endophyte-infected fescue. Experiment 4 investigated the changes in ruminal environment due to supplementation frequency. No differences were observed between supplementation frequencies for ruminal pH, ammonia, or VFA concentration, and DM, or CP digestibility. Therefore, the rumen maintained a hospitable environment to promote bacterial protein synthesis and fiber digestion with every 48 h supplementation. Backgrounding calves with high fiber co-product supplements or on novel endophyte fescue can enhance calf performance.
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    Effect of Timing of Insemination and Synchronization of Estrus Method on Artificial Insemination (AI) Pregnancy Rates in Beef Heifers
    Dorsey, Benjamin Reese (Virginia Tech, 2005-04-25)
    Objectives were to evaluate time of insemination relative to estrus and synchronization with melengestrol acetate (MGA) plus prostaglandin (PG) or progesterone insert (CIDR) plus PG on AI pregnancy rate in beef heifers (n = 662) during Fall or Spring. Fall heifers (n = 349) received MGA-PG (MGA for 14 d followed by PG on d 18) or CIDR-PG (CIDR for 7 d, PG administered 1 d before CIDR removal). Estrus was monitored by HeatWatch® (n = 200) or visually (n = 149). Spring heifers (n = 313) underwent CIDR-PG with detection of estrus by HeatWatch®. Heifers not in estrus by 96-100 h after PG were bred AI as non-responsive AI (NRAI). Across seasons, 548 heifers were bred following estrus (EAI). Heifers synchronized during the Fall with MGA received more (P < 0.05) mounts than Fall CIDR heifers (76.8 ± 6.7 and 47.6 ± 7.4, respectively), but duration of estrus was similar. Fall CIDR heifers had greater (P < 0.05) mounting activity and duration of estrus (47.9 ± 5.2 mounts and 15.5 ± 1.1 h) compared to Spring CIDR heifers (34.5 ± 3.1 mounts and 12.7 ± 0.6 h). Heifers grouped in 4 h blocks from 0 to 24 h had no difference (P > 0.05) in pregnancy rates (mean 62.5 %). Treatment had no effect (P > 0.05) on EAI pregnancy rates. Pregnancy rates across seasons for EAI, NRAI and overall was 61.0 %, 26.3 %, and 54.5%. In conclusion, a 24 h window may exist to successfully AI heifers.
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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.