Browsing by Subject "Intake"
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Item Determining biological sources of variation in residual feed intake in Brahman heifers during confinement feeding and on pasture(2009-05-15) Dittmar (III), Robert OttoObjectives were to characterize residual feed intake (RFI) and determine the phenotypic correlation between performance, feed efficiency, and other biological measurements in Brahman heifers, as well as the relationship between RFI determined in confinement and measurements of grazing activity on pasture. Three separate 70 d feeding trials were performed, and RFI was determined as the residual between actual and predicted dry matter intake (DMI) for a given level of production. Brahman heifers (n = 103; 5-to-9 mo of age) were individually limit-fed a pelleted 12% CP complete ration daily in Calan gates. Weekly body weight (BW) and DMI data were collected, and predicted DMI was determined by linear regression of actual DMI on mid-test metabolic BW. Ytterbium chloride was used to evaluate digestive kinetics, and fecal samples were collected to determine fecal volatile fatty acids (VFA) concentration and determine apparent dry matter digestibility (DMD) utilizing acid insoluble ash as an internal marker. Measurements of temperament were evaluated on all heifers at weaning. High (n = 6) and low (n = 6) RFI heifers (Exp. I) grazed fescue and ryegrass to determine variation in grazing behavior, DMI, and apparent DMD. Data from all three experiments were pooled, and RFI was not correlated with average daily gain (ADG), DMI, BW, partial efficiency of gain, feed conversion ration, fecal VFA concentration, or any measures of temperament. There were no significant differences in digestive kinetics between the RFI efficiency groups. Fecal samples taken for acid detergent insoluble ash (ADIA) determination were not collected at frequent enough intervals to account for weekly variation in fecal ADIA concentration. Pasture measurements were not different between the efficiency groups for heifers evaluated for grazing behavior, as well as estimated intake as a proportion of BW, or apparent DMD. Results of this study suggest that Bos indicus cattle appear to have similar efficiency traits as Bos taurus and Bos indicus influenced cattle, making this measure of efficiency equally as valid for use in both types of cattle. This indicates that selection based on RFI can be made to increase feed efficiency without affecting ADG or BW in Brahman cattle.Item Effects of Crude Protein Content on Intake and Digestion of Coastal Bermudagrass Hay by Horses(2011-08-08) Spurgin, Chelsey L.This study was conducted to determine the effect of forage CP level on intake and digestion of Coastal bermudagrass hay by horses. Four cecally fistulated geldings were used in a 4 x 4 Latin square design with four treatments and four periods. Horses were fed one of four Coastal bermudagrass hays consisting of 7, 10, 13, or 16% CP during each of the 4 15-d periods. Intake and apparent digestibility were determined for each horse at the end of each period by total fecal collection. In addition, cecal fluid and blood samples were collected from each horse on the last day of each period for determination of cecal ammonia, cecal pH, plasma urea nitrogen, and plasma glucose concentrations. Crude protein concentration of Coastal bermudagrass hay influenced equine intake and digestion. Increasing CP concentration linearly increased digestible OM intake (DOMI) from 3.79 to 5.98 kg/d for 7 and 16% CP hay, respectively (P = 0.04). Furthermore, as forage CP level increased, CP intake increased linearly (P < 0.01). Forage CP level had no effect on forage DM intake. Quadratic effects (P less than or equal to 0.05) were observed for forage OM, NDF, ADF, and digestible energy. Overall digestibility was lowest for the 7% CP hay and highest for the 10% CP hay. Cecal pH remained above 6.62 irrespective of treatment and time, indicating that cecal pH was suitable for microbial growth. As forage CP level increased, cecal ammonia concentration increased linearly from 0.03 mM for the 7% to 1.74 mM for the 15% CP hay (P < 0.01). Concentration of plasma glucose also linearly increased (P = 0.04) from 68.77 to 73.68 mg/dL as CP concentration increased from 7% to 16% CP. Plasma urea nitrogen exhibited a quadratic effect as concentration increased (P < 0.01) from 4.34 to 5.61 mM for the 7 and 16% CP hays, respectively.Item Evaluation of Intake Limiting Agents in a Self-fed Dried Distillers' Supplement(2013-08-14) Sugg, Joel DResponse to range supplementation is in part driven by level of supplement consumed and amount of associated variation. In order to evaluate intake limiting agents in a self-fed dried distillers? grain supplement (DDG), heifers (n=59) in Trial 1 were offered an ad libitum amount of sorghum ? sudangrass hay as well as DDG containing either no limiter (CON), monensin (185 mg/kg; MON), or one of six additional limiters alone or in combination with monensin (185 mg/kg, +M). Evaluated treatments and initial rates consisted of sodium chloride (NACL, 10%), urea (UREA, 2%), sodium bicarbonate (LIME, 1.68%), DL-malic acid (MLAC, 3%), calcium propionate (CAPR, 3%), and sodium bicarbonate plus urea (LIUR, 1.68% + 2%). Supplement intake was recorded daily and limiters were evaluated over three rates of inclusion, each for a duration of 14 d, on the basis of intake level, intake variation (cumulative stability), and rate of intake change over time (temporal stability). Data was analyzed as a 7 ? 2 factorial initial 7 days of each period were removed to avoid acclimation influence. A baseline period was observed to ensure no inherent differences were detected. Within the initial rate period, limiter affected OM intake (P = 0.02) as consumption was reduced by NACL (P < 0.01) and tended to be lower when limited by MLAC (P = 0.14) and LIUR (P = 0.11). Neither monensin (P = 0.86) nor a limiter ? monensin interaction were present. Cumulative stability was indicated that heifers consuming NACL (P < 0.01) and CAPR (P < 0.01) consumed supplement with greater regularity than did CONT. Monensin (P = 0.75) and monensin ? limiter (P = 0.76) did not influence intake stability. Temporal stability was unaffected by limiter (P = 0.43), monensin (P = 0.69), or monensin ? limiter (P = 0.93). When rate of inclusion was 2 ? initial rate, intake was affected by limiter (P < 0.01) with observations similar to the initial period. No monensin (P = 0.49) or interaction (P = 0.27) effect was present. Cumulative stability was unaffected by limiter (P = 022), monensin (P = 0.39), or interaction (P = 0.86). Temporal stability was increased with monensin (P 0.05) and an interaction resulted in an increased rate of supplement intake change in CONT when monensin was included. When supplement included limiters at 4 ? the initial rate, Effects on intake and cumulative stability by limiter were the only significant responses. Intake of LIUR, NACL, and MLAC were reduced relative to CONT while NACL was consumed with greater regularity. Trial 2 was conducted to further compare sodium chloride and DL-malic acid as limiting agents. Each were included in a self-fed DDG supplement offered to steers (n=60, mean initial BW = 191 kg) at identical rates (8%, 16% 24%, and 32%) in addition to monensin (66 mg/kg). Within each rate, MLAC reduced supplement intake more effectively than NACL while cumulative stability and temporal stability measures were similar among limiter and only deviated from control levels at lower rates.