Factors influencing the release rate of alkanes from an intra-ruminal, controlled-release device, and the resultant accuracy of intake estimation in sheep

2002 ◽  
Vol 53 (6) ◽  
pp. 681 ◽  
Author(s):  
H. Dove ◽  
R. W. Mayes ◽  
C. S. Lamb ◽  
K. J. Ellis
Keyword(s):  
Controlled Release ◽  
Release Rate ◽  
Feeding Frequency ◽  
Release Rates ◽  
Castrate Male ◽  
Once Daily ◽  
Faecal Output ◽  
Factors Influencing ◽  
Herbage Intake ◽  
Release Devices

Two experiments were conducted to evaluate factors influencing the release rate of octacosane (C28) and dotriacontane (C32) synthetic alkanes from controlled-release devices (CRD) inserted into the rumen of sheep, and the resultant accuracy of alkane-based estimates of herbage intake. In the first experiment, estimates of the rate of release of alkanes from CRD suspended in the rumen of 7 rumen-fistulated ewes were obtained by directly measuring the rate of CRD plunger travel. In the second experiment, CRD were administered orally to 24 castrate male sheep to evaluate the effects of level of feeding (1200 v. 600 g DM/day), frequency of feeding (continuous v. once-daily), and number of CRD inserted (1 v. 2) on temporal trends in faecal alkane concentrations and ratios and on the accuracy of estimation of intake. In both experiments, animals were also dosed orally, once daily with paper pellets containing 56 mg hexatriacontane (C36). In Expt 1, linear alkane release from the CRD commenced after a lag period of 2-3 days, at mean rates of 40.1 mg/day (C28) and 41.7 mg/day (C32), close to the desired rates of 40 mg/day. There was no evidence of curvilinearity, and differences in release rate between sheep were small (CV 4.1%). Alkanes attributable to the CRD appeared in faeces after 2-3 days and reached plateau concentrations by 6-7 days. Data are presented to indicate that the release rate was not affected by the removal of CRD from the rumen for measurement, and that the release rates in fistulated (Expt 1) and intact sheep (Expt 2) were similar. In Expt 2, there was no effect of level of feeding on CRD release rates and faecal alkane concentrations were consistent with the differences in faecal output caused by feeding level. As a result, the accuracy with which known intakes were estimated was unaffected by level of feeding. Similarly, there were no effects of feeding frequency on the accuracy of estimated intake, implying that in this study, feeding frequency had no effect on CRD release rates. The administration of 2 CRD to half the animals in this experiment increased faecal concentrations of C28 and C32 and the synthetic : herbage alkane ratios associated with these alkanes [e.g. faecal C32 : tritriacontane (C33)] but these changes were not significantly different from those expected from the release rates estimated in Expt 1. As a result, the accuracy with which known intakes were estimated was not influenced by the number of CRD administered. In both experiments, once-daily dosing with C36 alkane resulted in a more rapid rise in faecal C36 concentrations and faecal C36 : pentatriacontane (C35) ratios to maximal levels (3-4 days), compared with alkanes derived from the CRD (6-7 days), but thereafter, faecal C36 concentrations were much more variable, especially in the fistulated sheep. As a result, intake estimates based on the C36 : C35 alkane pair significantly over-estimated known intakes by 13% (Expt 1) and 8% (Expt 2). Data are presented to indicate that C36 alkane functioned satisfactorily as a faecal output marker and, with C32 : C33 estimates of intake, provided accurate estimates of herbage digestibility. The results indicate that intra-ruminal controlled-release devices provide a satisfactory means of delivering an accurate, daily dose of alkanes for the estimation of herbage intake, faecal output, and digestibility in sheep.

Evaluation of controlled release devices for administration of chromium sesquioxide using fistulated grazing sheep. 1. Variation in marker concentration in faeces

1990 ◽  
Vol 41 (5) ◽  
pp. 969 ◽  
Author(s):  
EP Furnival ◽  
JL Corbett ◽  
MW Inskip
Keyword(s):  
Controlled Release ◽  
Circadian Variation ◽  
Grab Sampling ◽  
Once Daily ◽  
Gelatin Capsules ◽  
Faecal Output ◽  
Release Device ◽  
Daily Sampling ◽  
Release Devices ◽  
Representative Samples

A group of 10 sheep grazed as a single flock; five were dosed with chromium sesquioxide (Cr2O3) using an experimental controlled release device, and five were dosed twice a day with gelatin capsules. Total faecal output was collected from each sheep over a period of 13 days, and in addition, a sample was taken twice daily from the rectum (grab sample). In a second experiment total faeces were collected every 2 h for 24 h. Total faecal output was compared with estimates of faecal output calculated from the quantity of Cr2O3 in the dose, and the concentrations in representative samples and in grab samples of faeces. An examination was made of the biases in the estimates from these two types of samples for the controlled release devices and for the gelatin capsules. Use of the controlled release devices significantly reduced circadian variation in the Cr2O3concentration in faeces, compared with twice daily dosing with gelatin capsules. Consequently variability was lower and biases in estimates of faecal output were relatively small. Once daily grab sampling from sheep with controlled release devices produced more reliable estimates of faecal output than twice daily sampling from sheep with gelatin capsules.

Performance of Controlled Release Dispensers for Grandlure, the Pheromone of the Boll Weevil (Coleoptera: Curculionidae)2

1990 ◽  
Vol 25 (3) ◽  
pp. 414-426 ◽  
Author(s):  
B. A. Leonhardt ◽  
W. A. Dickerson ◽  
R. L. Ridgway ◽  
E. D. DeVilbiss
Keyword(s):  
Controlled Release ◽  
Release Rate ◽  
Emission Rate ◽  
Boll Weevil ◽  
Emission Rates ◽  
Release Rates ◽  
Cigarette Filter ◽  
Temperature Changes

Comparison of laboratory-measured release rates with boll weevil captures showed that dispensers containing 10 mg of grandlure with a release rate of 10 μg/hr or higher generally produced weevil captures which were at least 50% as high as those with the reference, fresh cigarette filter. Emission rates of ca. 3 μg/hr or lower and amounts of residual grandlure of ≤ 2 mg generally resulted in weevil captures below the 50% threshold. Comparisons of commercial dispenser formulations containing 10 mg of grandlure showed that a Hereon orange plastic laminate (H-OL-T) was most effective in prolonging the release of grandlure in both field and laboratory evaluations. Its emission rate was least affected by temperature changes. Scentry PVC dispensers (S-T-T, S-C-T, S-S-T, and S-YS-T) and the Consep membrane (C-M-T) lost grandlure more rapidly than did the laminate; however, differences in weevil captures were often not significant. Fermone black PVC squares (F-S-T and F-OS-T), AgriSense polymeric rods, (A-50R-T and A-35R-T) and the cigarette filter (CF-T) were less effective in extending the release of grandlure. Dispensers mounted in the capture cylinder lost grandlure more rapidly than did similar dispensers mounted in the cooler trap base. A layer of stickum on one side of flat dispensers to facilitate attachment to the trap resulted in a somewhat lower release rate of grandlure.

Lipid-Based Implants: Impact of Formulation Parameters

2014 ◽  
Vol 1060 ◽  
pp. 87-90
Author(s):  
Marisa Nicolai ◽  
Vanessa Amaral ◽  
Cátia Antunes ◽  
Duangratana Shuwisitkul ◽  
Joana Portugal Mota
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Release Rate ◽  
Release Rates ◽  
Drug Release Rate ◽  
Blend Ratio ◽  
Drug Type ◽  
Formulation Parameters ◽  
Blend Ratios ◽  
Aqueous Solubilities

Lipid implants have been attracting attention in recent years. However, to better understand these systems, more fundamental studies are required. The objective of this work was to evaluate the effect of some formulation parameters, namely lipid and drug type, implant shape/surface area and lipid blend ratio, on drug release rate. The developed implants were cylindrical or spherical in shape with an even surface. Caffeine release from glycerol-trimyristate implant was very fast when compared with glycerol-tristerate matrix. The latter allowed a 4 month controlled release in contrast with glycerol-trimyristate matrix (~ 5 days). Caffeine and theophylline presented similar release rates, despite their different aqueous solubilities. In addition, different lipid blend ratios provided different release profiles for caffeine.

scholarly journals Estimation of feed intake by cattle using controlled-release capsules containing n-alkanes or chromium sesquioxide

2004 ◽  
Vol 142 (2) ◽  
pp. 225-234 ◽  
Author(s):  
L. M. M. FERREIRA ◽  
M. OLIVÁN ◽  
M. A. M. RODRIGUES ◽  
K. OSORO ◽  
H. DOVE ◽  
...  
Keyword(s):  
Controlled Release ◽  
Release Rate ◽  
Feed Intake ◽  
Dry Weight ◽  
Average Weight ◽  
Release Rates ◽  
Grab Sampling ◽  
Holstein Friesian ◽  
The Mean ◽  
Friesian Cows

An experiment was carried out to evaluate the utilization of the n-alkane technique and the chromium sesquioxide (Cr2O3)/acid insoluble ash (AIA) procedure to estimate feed intake of meadow hay by two breeds of cattle. The animals were housed in individual pens, and offered known amounts of meadow hay as the sole diet component. One group of 4 Barrosã cows (average weight, 457±24 kg) and another group of 4 Holstein–Friesian cows (average weight, 635±148 kg) were dosed with intra-ruminal controlled-release capsules (CRC) that contained alkane markers or Cr2O3 in separate capsules. During intake estimation, meadow hay and faeces were sampled twice daily. There was no significant effect of grab sampling time on the meadow hay intake estimation, due to the fact that no differences were observed in the faecal marker concentrations.The mean real intakes, measured as the difference between the dry weight of feed offered each day and the dry weight of daily feed refusal, were 5·64 and 7·76 kg DM/day for Barrosã and Holstein–Friesian cows, respectively. For Barrosã cows the mean estimated intakes when using the CRC release rates documented by the manufacturer (MRR) were 5·66, 6·59 and 6·90 kg DM/day, using the Cr2O3/AIA procedure, C31[ratio ]C32 and C33[ratio ]C32 n-alkane pairs, respectively. For Holstein–Friesian cows the same markers gave values of 7·72, 8·51 and 8·95 kg DM/day, respectively. Mean daily intake estimation was improved when the release rate calculated as the reduction rate in CRCs payload performed in a additional experiment (CRR), was used. The differences from the real intake values, obtained using C31[ratio ]C32 and C33[ratio ]C32 alkane pairs, decreased from 950 and 1260 g/day to 140 and 420 g/day, respectively, for Barrosã cows and from 750 and 1190 g/day to 290 and 90 g/day for Holstein–Friesian cows. The intake estimation using the Cr2O3/AIA procedure was not affected by correcting the CRC release rate, because the release rates of both MRR and the CRR were similar.The results indicate that controlled-release capsules provide a uniform marker release in cattle, but also suggest that to obtain accurate estimates of intake, it is better to measure release rates within the context of particular experiments.

Estimation of intake and digestibility of silage by beef steers using a controlled release capsule of n-alkanes

2003 ◽  
Vol 83 (4) ◽  
pp. 761-768 ◽  
Author(s):  
E. Charmley ◽  
D. R. Ouellet ◽  
D. M. Veira ◽  
R. Michaud ◽  
J. L. Duynisveld ◽  
...  
Keyword(s):  
Controlled Release ◽  
Release Rate ◽  
High Standard ◽  
Standard Errors ◽  
Beef Steers ◽  
Release Rates ◽  
Significant Difference ◽  
Fecal Recovery ◽  
Ad Libitum ◽  
Predicted Values

Twelve beef steers were fed a grass-legume silage either ad libitum or at 70% of ad libitum feeding. Intake and digestibility were measured directly or predicted using the alkane ratio technique. The C32 and C36 alkanes were delivered via a controlled release capsule (CRC) in the rumen. Level of feeding had no effect on digestibility (P > 0.05) but dry matter (DM) intake tended to be greater for steers fed ad libitum (P = 0.08). The release of alkanes from the CRC was erratic and 20% greater than expected. This influenced the exogenous to endogenous alkane ratios. Estimates of intake were therefore derived using both the expected and actual (determined from total collection of feces and their alkane analysis) exogenous alkane release rates. Estimated intakes based on the manufacturers’ release rate were underestimated and associated with high standard errors. For cattle fed restricted silage, estimated intakes obtained with C31:C32, C33:C32 and C33:C36 alkane pairs and using actual measured release rates of exogenous markers were associated with lower standard errors and averaged 87, 102 and 103% of actual values, respectively. For ad libitum-fed cattle the corresponding values were 81, 96 and 96% of actual values. There was no significant difference between actual and estimated DM intake when the C33:C32 and C36:C32 alkane pairs were used. The precision of intake estimates using manufacturers release rates for exogenous alkanes was poor, as evidenced by significant discrepancies (P < 0.05 for four of six estimates) between observed and predicted values averaging 2.26 kg or 30% of DM intake. However, when measured exogenous alkane release rates were used, standard errors were reduced and discrepancies for estimates using C33:C32 and C33:C326 were only 0.4 kg or 6% of DM intake. Fecal recovery of C27, C29, C31 and C33 alkanes was 73.4, 92.7, 85.6 and 100%, respectively. Both C29 and C33 gave good estimates of digestibility because of high recovery. Observed and estimated values were not significantly different. It is concluded that exogenous alkane release from CRCs was not satisfactorily consistent. Reliable estimates of intake could only be made if actual release rate was known. Endogenous alkanes can be used for determination of digestibility, provided fecal recovery is known. Key words: Beef, silage, alkane, intake, digestibility

Evaluation of controlled release devices for administration of chromium sesquioxide using fistulated grazing sheep. 2. Variation in rate of release from the device

1990 ◽  
Vol 41 (5) ◽  
pp. 977 ◽  
Author(s):  
EP Furnival ◽  
KJ Ellis ◽  
FS Pickering
Keyword(s):  
Controlled Release ◽  
Dry Matter ◽  
Statistical Correlation ◽  
Faecal Output ◽  
Merino Sheep ◽  
Coefficients Of Variation ◽  
Release Device ◽  
Flow Through ◽  
The Mean ◽  
Release Devices

Merino sheep fitted with rumen cannulae and varying in liveweight, grazed Phalaris aquatica pastures with high and low dry matter mass. One or more controlled release devices were tethered inside the rumen and attached to its cannula. The position of the plunger within the controlled release device was recorded every 2 or 3 days for periods of up to 19 days, and the mean rate of plunger movement was calculated. Faecal output and flow of rumen digesta were measured concurrently in two experiments. Rate of plunger movement was measured in 152 devices and found to be substantially constant over time, but significant differences in mean rate of plunger movement were observed between formulation type, between sheep and between pastures varying in herbage mass. Coefficients of variation between sheep ranged from � 6 to �14%, and differences between pasture means ranged from 1 to 14%. Some of this variation was associated statistically with faecal output; assuming a linear relationship, a change in dry matter output of 100 g/day was associated with a change in plunger rate of 0.05 mm/day or about 6% of the mean rate. Liquid flow through the rumen was the rumen variable which had the highest statistical correlation with the rate of plunger movement.

Evaluation of a Soil Incubation Method to Characterize Nitrogen Release Patterns of Slow- and Controlled-Release Fertilizers

2014 ◽  
Vol 97 (3) ◽  
pp. 643-660 ◽  
Author(s):  
L Carolina Medina ◽  
Jerry B Sartain ◽  
Thomas A Obreza ◽  
William L Hall ◽  
Nancy J Thiex
Keyword(s):  
Controlled Release ◽  
Release Rate ◽  
Nutrient Release ◽  
Soil Incubation ◽  
Release Rates ◽  
N Release ◽  
Production And Distribution ◽  
Slow Release Fertilizers ◽  
Incubation Temperatures ◽  
Controlled Release Fertilizers

Abstract Several technologies have been proposed to characterize the nutrient release patterns of slow- release fertilizers (SRF) and controlled-release fertilizers (CRF) during the last few decades. These technologies have been developed mainly by manufacturers, and are product-specific, based on the regulation and analysis of each SRF and CRF product. Despite previous efforts to characterize SRF and CRF materials, no standardized, validated method exists to assess their nutrient release patterns. However, the increased production and distribution of these materials in specialty and nonspecialty markets requires an appropriate method to verify product claims and material performance. A soil incubation column leaching procedure was evaluated to determine its suitability as a standard method to estimate nitrogen (N) release patterns of SRFs and CRFs during 180 days. The influence of three soil/sand ratios, three incubation temperatures, and four soils on method behavior was assessed using five SRFs and three CRFs. In general, the highest soil/sand ratio increased the N release rate of all materials, but this effect was more marked for the SRFs. Temperature had the greatest influence on N release rates. For CRFs, the initial N release rates and the percentage N released/day increased as temperature increased. For SRFs, raising the temperature from 25 to 35°C increased initial N release rate and the total cumulative N released, and almost doubled the percentage released/day. The percentage N released/day from all products generally increased as the texture of the soil changed from sandy to loamy (Iowa&gt;California&gt;Pennsylvania&gt;Florida). The soil incubation technique was demonstrated to be robust and reliable for characterizing N release patterns from SRFs and CRFs. The method was reproducible, and variations in soil/sand ratio, temperature, and soil had little effect on the results.

Assessment of a Once-Daily Controlled-Release Ibuprofen Matrix Tablets Prepared Using Eudragit®E100/Carbopol®971P NF Polymers and Their Salts Combinations.

2021 ◽  
Vol 18 ◽  
Author(s):  
Wasfy Obeidat ◽  
Mohammad Mohammad Al Natour
Keyword(s):  
Controlled Release ◽  
Aqueous Media ◽  
Weight Ratio ◽  
Single Layer ◽  
Matrix Tablets ◽  
Matrix Tablet ◽  
Release Rates ◽  
Once Daily ◽  
Bilayer Tablet ◽  
Salt Forms

Introduction: Hydrophilic polymers that swell or dissolve in aqueous media can have the potential to prepare controlled/sustained dosage forms for weakly acidic, poorly soluble drugs. Objective: The main objective of this study is to utilize Eudragit®E100 (EE) and Carbopol®971P NF (Cp) polymers and their salt forms in the preparation of a once-daily controlled-release matrix tablet for model drug, Ibuprofen (IB). Methods: Combinations of the polymers in their base forms (EE)/(Cp) or their salt forms (EEHCl/CpNa) were compressed with (IB) into single layer matrix tablets, or otherwise into bilayer tablets. Dissolution profiles were constructed using three different consecutive stages (pH 1.2, 4.8, and 6.8). Result: It was found that the incorporation of (EEHCl) modified the release rates of (IB) from (Cp) based matrix tablets. However, a major enhancement of (IB) release rates occurred when the polymers were combined in their salt forms at a 1:1 ratio by weight. In addition, a bilayer tablet was prepared wherein a relatively rapidly disintegrating layer composed of polymers salts (EEHCl and CpNa), and a second layer containing only (Cp) polymer in its base form at a 1:2 weight ratio possessed excellent release properties, and mechanical strengths. Conclusion: It was concluded that the prepared bilayer tablet could be of promise use in controlling the release rates of (IB) in an extended manner to allow once-daily administration with an improved pH-independent release behavior.

Irrigation Volume, Application, and Controlled-release Fertilizer II. Effect on Substrate Solution Nutrient Concentration and Water Efficiency in Containerized Plant Production

1998 ◽  
Vol 16 (3) ◽  
pp. 182-188
Author(s):  
Kelly M. Groves ◽  
Stuart L. Warren ◽  
Ted E. Bilderback
Keyword(s):  
Controlled Release ◽  
Irrigation Efficiency ◽  
Plant Production ◽  
Water Efficiency ◽  
Solution Ph ◽  
Entire Study ◽  
Once Daily ◽  
Substrate Solution ◽  
Irrigation Volume ◽  
Controlled Release Fertilizers

Abstract Rooted cuttings of Cotoneaster dammeri Schneid ‘Skogholm’ and seedlings of Rudbeckia fulgida Ait. ‘Goldsturm’ were potted into 3.8 liter (4 qt) containers in a pine bark:sand (8:1 by vol) substrate incorporated with 3.5 g (0.12 oz) N per container provided by one of the following five controlled-release fertilizers (CRFs): Meister 21N–3.5P–11.1K (21–7–14), Osmocote 24N–2.0P–5.6K (24–4–7), Scotts 23N–2.0P–6.4K (23–4–8), Sustane 5N–0.9P–3.3K (5–2–4) or Woodace 21N–3.0P–9.5K (21–6–12). Two hundred ml (0.3 in), 400 ml (0.6 in), 800 ml (1.1 in) or 1200 ml (1.7 in) of water was applied once daily (single) or in two equal applications with a 2 hr interval between applications (cyclic). Substrate solutions were collected from containers of cotoneaster 15, 32, 45, 60, 74, 90, 105, and 119 days after initiation (DAI). Irrigation efficiency [(water applied − water leached) ÷ water applied] was determined on the same days. Cyclic application improved irrigation efficiency at 800 ml (1.1 in) and 1200 ml (1.7 in) ≈ 27% compared to a single application. Irrigation efficiencies averaged over the season were 95%, 84%, 62%, and 48% for cotoneaster and 100%, 90%, 72%, and 51% for rudbeckia at 200 ml (0.3 in), 400 ml (0.6 in), 800 ml (1.1 in) and 1200 ml (1.7 in), respectively. NH4-N and NO3-N and PO4-P concentrations in substrate solution decreased with increasing irrigation volume regardless of CRF. Substrate NH4-N concentration decreased throughout the season with most CRFs below 5 mg/liter by 90 DAI. CRFs mainly affected substrate NH4-N and NO3-N concentrations when irrigated with 200 ml (0.3 in) or 400 ml (0.6 in). Substrate NH4-N, NO3-N, and PO4-P solution concentrations were similar for all CRFs at irrigation volume of 1200 ml (1.7 in). Osmocote, Scotts, and Woodace maintained relatively constant substrate solution levels of PO4-P through 60 DAI. By 90 DAI, substrate PO4-P levels were similar regardless of irrigation volume or CRF. Substrate PO4-P concentrations were never in the recommended range of 5 to 10 mg/liter when irrigated with 800 ml (1.1 in) or 1200 ml (1.7 in) regardless of CRF. Solution pH remained in the recommended range of 5.0 to 6.0 for all irrigation volumes and CRFs throughout the entire study with the exception of Sustane.

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