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Management And Dietary Strategies To Mitigate Environmental Stressors In Northern Plains Cattle Feeding Systems, Warren Carl Rusche
Management And Dietary Strategies To Mitigate Environmental Stressors In Northern Plains Cattle Feeding Systems, Warren Carl Rusche
Electronic Theses and Dissertations
Three studies were undertaken to examine strategies to mitigate environmental stress faced by Northern Plains cattle feeders. In the first study, 46 feedlot managers from SD (n = 21), MN (n = 6), and NE (n = 19) were surveyed on use and perceptions of heat stress (HS) mitigation strategies. All respondents avoided cattle handling during heat stress events and incorporated some method of HS mitigation. Buildings or shades were perceived as the most successful strategy (60.9%) and were most commonly named as strategies managers would like to employ (63% for shades and 17.4% for buildings). Increasing dietary corn silage …
Receiving And Backgrounding Phase Management: The Effects Of Receiving Diet Roughage Source And Backgrounding Phase Rate Of Gain On Performance Of Feedlot Cattle, Ethan J. Blom
Electronic Theses and Dissertations
Management of cattle during the receiving and backgrounding phases can influence the performance of feedlot cattle. The receiving phase is a stressful time for cattle entering the feedlot and quickly adapting cattle to milled feed can impact their productivity. Silages are often viewed as less desirable feedstuffs in receiving diets for newly-weaned calves. The objective of this 2-yr study was to evaluate effects of roughage source in receiving diets on cattle performance, diet mixing, and diet integrity. Steer calves (yr 1, n = 180; yr 2, n = 210) were weaned and immediately transported 580 km. Calves were allotted to …
Lysine Bioavailability Of Two Lipid Coated Lysine Products After Exposure To Silages With Different Acidity, Jessica N. Reiners
Lysine Bioavailability Of Two Lipid Coated Lysine Products After Exposure To Silages With Different Acidity, Jessica N. Reiners
Electronic Theses and Dissertations
Three experiments were conducted to determine bioavailability of 2 lipid coated Lys products (EB and EC). In an initial experiment, Lys disassociation from 2 lipid coated Lys products was best described by a first-order kinetic model after incubation in alfalfa- or corn-silage at 2 different amounts of acidity. Greater amounts of Lys immediately disassociated from EC (15.7%) than EB (4.9%; P < 0.05). Lysine that initially disassociated in corn silage at low pH (0.5%) was less than corn silage at a more neutral pH (18.7%), whereas Lys that initially disassociated in alfalfa silage was not affected (P = 0.26) by pH. Lysine that slowly disassociated from lipid coated Lys differed by product (P = 0.01), and acidity (P < 0.01) affected amounts of Lys that slowly disassociated differently within alfalfa- or corn-silage (pH × silage = 0.02). Greater amounts of Lys disassociated from acidic corn silage (79%) than neutral corn silage (32%; P = 0.01). However, amounts of Lys that slowly disassociated from alfalfa silage was not impacted by acidity (P = 0.40). Additionally, amounts of Lys that did not disassociate (P < 0.04) within 24 h were greater (P < 0.04) when lipid coated Lys was mixed with neutral silages (44%) compared to acidic silages (21%). However, rate of Lys disassociation from lipid coated Lys products was not affected by acidity or exposure to alfalfa- or corn-silage (P = 0.21). In a second experiment, we measured in vitro ammonia release from EB and EC after mixing with alfalfa- or corn-silage at different amounts of acidity with or without monensin. Ammonia release from Lys increased (Quadratic < 0.01) with greater amounts of time; however, differences between in vitro cultures with added Lys and negative control were not detected until 36 h of incubation. By 36 h, all cultures containing added Lys were greater than the negative control. After 42 h of incubation, ammonia release from Lys was greatest from EC and when lipid and Lys-HCl in amounts identical to EB were provided to cultures; EB, Lys-HCl, and lipid and Lys in amounts identical to EC were intermediate. After 48 h of incubation, ammonia release from Lys in EB was greatest and Lys-HCl was least, but EC and amounts of lipid and Lys-HCl identical to either EB or EC were intermediate. Ammonia release from Lys were less from cultures containing monensin after 48 h of incubation. In experiment 3, 9 white-faced ewes (70.1 ± 5.2 kg BW; 5.3 ± 0.6 yr) were used to measure Lys bioavailability by a slope-ratio analysis from 2 lipid coated Lys products and Lys-HCl after mixing in corn silage. Plasma Lys concentrations increased (Linear < 0.01) in response to abomasal infusion of Lys, and bioavailability of EB, EC, and Lys- HCl were calculated to be 10.74%, 18.82%, and 11.87%, respectively. However, increases in plasma Lys from EB (Linear = 0.41) and Lys-HCl (Linear = 0.36) were not different from plasma Lys supported by diet alone, but the rate of increase in plasma Lys in response to EC tended (Linear = 0.15) to be greater than plasma Lys levels from diet. Evidently, manufacturing method among lipid coated Lys products as well as physical and chemical characteristics of diet can impact availability of Lys from lipid coated Lys products.