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Biomedical subjects

W C Ellis

Publications and source records attributed to W C Ellis.

15 recordsLinked to original sources
PubMed1991

Characterization of relative growth of empty body and carcass components for bulls from a five-breed diallel.

Slaughter and carcass data were obtained on 197 bulls produced in a diallel involving Angus, Brahman, Hereford, Holstein and Jersey that were slaughtered at either 6, 9, 12, 15, 18, 24, or 30 mo of age. Bulls were given ad libitum access to a 72% TDN diet on an individual basis from 6 mo of age until slaughter. Empty body weight (EBWT) was determined as the sum of the weights of blood, hide, hard drop, soft drop (minus contents of the digestive tract), and carcass weight (CWT), which were recorded at slaughter. Carcass protein (CPROT) and fat (CFAT) were based on weights and chemical analyses of lean and fat tissue and bone of the carcass. Empty body protein (EBPROT) and fat (EBFAT) were based on weights and chemical estimates of the components of the empty body. Growth of EBWT, EBPROT, EBFAT, CWT, CPROT, and CFAT relative to either live weight (LWT), EBWT, or CWT were investigated using the allometric equation. Breed-type differences existed (P less than .01) for the growth of EBWT relative to LWT. Comparisons of general combining abilities revealed that Angus, Hereford, and Jersey generally had lower maturing rates of EBWT relative to LWT and that Brahman and Holstein had higher maturing rates. Across breed-type, relative growth rates indicated that fat and protein were later-maturing components relative to LWT, EBWT, or CWT, which implies that other components mature relatively earlier. Relative maturing rates of components studied were not important in explaining differences in body composition that have been previously reported for these breed-types.

Adipose Tissue↗
PubMed1991

Effects of methionine hydroxy analog on voluntary intake, digestibility, nitrogen balance, and chewing behavior in sheep fed grass silage.

Voluntary intake, digestibility, N balance, and chewing behavior of six 6-mo-old (young) and six 30-mo-old (mature) Texel wethers (32.6 and 83.1 kg average BW) given ad libitum access to grass silage and 100 g of top-dressed soybean meal with or without 5 g of methionine hydroxy analog (MHA) in the acid form were examined according to a two-period crossover design. Supplementation level of MHA in the acid form corresponded to .32 and .16 g of MHA/kg BW.75, respectively, in young and mature wethers. There was no effect (P greater than .10) of MHA on mean voluntary DMI. Methionine hydroxy analog supplementation increased (P less than .02) digestibility of DM, OM, and CP by young wethers but not (P greater than .18) by mature wethers. The MHA decreased eating time (P less than .03) in both young and mature wethers and intake level (P = .01) in young wethers during the first 1.5 h of access to grass silage. With MHA, both age groups increased (P less than .05) the daily number of meals and decreased (P less than .02) the mean duration of each meal. There was no effect (P greater than .06) of MHA on daily and unitary eating, ruminating, and masticating times; however, mean duration of consecutive rumination bolus cycles was longer (7.2%; P = .01) in young wethers. Young vs mature sheep ate more (53.4 vs 39.3 g of DM/[d.kg BW.75]; P less than .001) and had shorter unitary mastication times (P = .001). Results suggest that, depending on its relative level of supplementation, MHA in the acid form could act through both palatability and effects on ruminal metabolism.

Animal Feed↗
PubMed1990

The flow of undigested corn residues through the gastrointestinal tract of cattle.

Two experiments were conducted to measure effects of source and level of roughage on the flow of corn residues through the gastrointestinal tract of cattle. In Exp. 1, steers (195 kg) were fed diets of ground corn with 0, 30 or 60% of ground Coastal bermudagrass hay (Cynodon dactylon) [L.] Pers.) at intakes of 1, 1.5 or 2% of BW in a 9 x 9 Latin square. Experiment 2 consisted of two 4 x 4 Latin squares with either rice hulls (square 1) or ground Coastal bermudagrass hay (square 2) providing 0, 7.5, 15 or 30% of the total diet fed at 1.5% of BW. After a 28-d adjustment period, a portion of the corn in one meal was replaced with cracked corn stained with brilliant green. The concentrations of stained corn residues appearing in the feces subsequent to dosing were fitted to a one-compartment, age-dependent model and compartmental mean residence time (CMRT) and time delay (tau) were estimated. In Exp. 1, increasing the level of intake of the ration from 1% to 1.5 or 2.0% of BW increased (P less than .05) CMRT by 52% and reduced (P less than .05) tau by 41%. In Exp. 2, source of roughage had no effect (P = .95) on CMRT or tau. Combined results of the two experiments indicated that increasing proportion (P) of either roughage was associated with an exponential decline in CMRT of stained corn residues (CMRT = 1211 * e-.0315P) from rations consumed at 1.5 and 2.0% of BW. No consistent effect of roughage type or proportion was noted on time delay in the two experiments collectively. These results indicate that increasing the proportion of roughage in the diet exponentially reduces residence time of corn residues in the ruminoreticulum (CMRT) without affecting residence time in the postgastric segments (tau).

Analysis of Variance↗
PubMed1990

Fragmentation and ruminal escape of particles as related to variations in voluntary intake, chewing behavior and extent of digestion of potentially digestible NDF in heifers.

The distribution of particles of differing sizes in ruminal, duodenal and fecal samples, the efficiency of particle breakdown and ruminal escape and their relationships to voluntary intake, chewing behavior and extent of digestion of potentially digestible NDF were examined in six heifers (290 kg average BW) with ruminal, duodenal and ileal cannulas. Animals had ad libitum access to corn silage, with or without 100 mg monensin head-1.d-1, in a two-period crossover design. Variations in voluntary intake by individual animals were positively related to size of digesta particles (median retaining aperture, MRA) in the dorsal rumen (P = .07) and rectum (P = .08), but not to MRA of particulate matter from the ventral rumen and duodenum. No significant relationships existed among eating or ruminating activities and distribution of particles of differing sizes in digesta from any of the digestive sites. The MRA of particulate matter in duodenal and rectal digesta were negatively related (P = .08 and P = .10) to extent of digestion of potentially digestible NDF (PDNDF) at these sites. Voluntary intake was related positively to efficiency of ruminative degradation of digesta particles appearing at the duodenum (P = .09) and to duodenal DM digesta flow per opening of the reticulo-omasal orifice (ROO; P = .02), the latter being negatively related to extent of digestion of PDNDF in duodenal digesta (P = .09). These results suggest that animals with higher intake capability are more efficient ruminators and can partially override constraining factors of particle size and byoyancy and thereby achieve a larger amount of DM flowing per opening of the ROO.

Animal Feed↗
PubMed1989

Quantitative analysis of nycterohemeral eating and ruminating patterns in heifers with different voluntary intakes and effects of monensin.

The nycterohemeral pattern of eating and ruminating behavior was examined in six heifers given ad libitum access to a corn silage-based diet with or without 100 mg monensin.hd-1.d-1 in a two-period crossover design. Rhythm components (no. of cycles/24 h) were characterized by the finite Fourier transform of 24-h mastication activities series measured over 7 d. Analysis of variance of the daily mean of hourly activities and rhythm components 1 to 12 showed significant effects of heifer (H), monensin treatment (T), period (P) and T x P x H interactions. A reparameterization of the finite Fourier transform yielded the amplitude and the phase for each rhythm component and allowed the plot of periodograms and phase diagrams, respectively. Rhythm components 1, 2 and 3 contributed primarily in explaining the total dispersion of 24-h eating and ruminating mastication series. The major effect of monensin was to increase the phase at rhythm component 1, delaying by 1 h in the onset of rumination after the morning feeding. Heifer effects were significant and appeared related to variations in daily voluntary intake (VI) of individual heifers. Heifer 5, with the largest VI, had two main eating periods and the highest rate of eating. Heifer 4, with the smallest VI, partitioned mastication activity throughout the day into four main eating and ruminating periods. Differences among animals in their nycterohemeral chewing behavior patterns may be related to differences in forestomach structure associated with a larger VI capacity by animals having mastication rhythm components 1 and 3.

Analysis of Variance↗
PubMed1989

Passage of chromium-mordanted and rare earth-labeled fiber: time of dosing kinetics.

Coastal bermudagrass hay was labeled with Cr by the Cr-mordant procedure and with 177Lu applied to the same fiber. Neutral detergent fiber prepared from the same Coastal bermudagrass hay was labeled with Yb, 169Yb, Tb and 160Tb by soaking overnight following by thorough washing and drying. Wood chips were similarly labeled with Sm or La, and Solka Floc was labeled with 147Nd and 141Ce. The carriers, labels and times of administration to cattle were: bermudagrass fiber with both Cr and 177Lu, bermudagrass fiber with 169Yb and Solka Floc labeled with 147Nd at 0 h; bermudagrass fiber with Yb, Solka Floc with 141Ce and wood chips with Sm at 24 h; wood chips with La at 48 h; and bermudagrass fiber labeled with 160Tb at the beginning and labeled with Tb at the end of a meal. Fecal collection followed and passage characteristics were determined with a two-compartment, age-dependent model. Markers labeling the different fiber sources had different (P less than .01) passage rates (Solka Floc greater than Coastal bermudagrass greater than wood chips), but there was no difference within fiber source for rare earth passage. There also was no difference between the passage characteristics of Cr-mordant and 177Lu. However, passage rate of particles administered at the beginning of the meal (160Tb) was 42% higher than for particles at the end of the meal (Tb).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effects of time of day and monensin on the size distribution of particles in digestive tract sites of heifers fed corn silage.

Effects of time of day and dietary monensin in the distribution of size of digesta particles in different digestive tract sites and their intersite relationships were examined in six heifers (290 kg BW) with ruminal, duodenal and ileal cannulas given ad libitum access to corn silage, with or without 100 mg monensin.head-1.d-1, in a two-period crossover design. Ingestive masticate and digesta of corn silage were collected via esophageal, ruminal or intestinal cannulas. The distribution of particulate matter retained on sieves with apertures larger than 20 microm was determined by wet-sieving. The cumulative distribution of particulate matter on a series of sieves was regressed on retaining sieve aperture to estimate the sieve aperture that would retain 50% weight of the particulate matter (median retaining aperture, MRA). The MRA of masticate was 6,494 microm. The MRA of digesta particles decreased (P less than .05) from ventral rumen (1,847 microm) to dorsal rumen (1,797 microm) to duodenum (346 microm), but increased to the rectum (359 microm). The MRA was lower (P = .044) for the monensin treatment only in feces. The MRA of particulate matter in the dorsal and ventral rumen, duodenum and rectum all changed (P less than .05) over 24 h. An inverse pattern between the MRA of ruminal and duodenal digesta occurred, presumably the result of a nycterohemeral pattern of eating and ruminating activity. Across sampling times, an inverse relationship existed between MRA of ventral rumen and duodenal digesta. This relationship suggests that a ruminal digesta raft composed of larger particles (immediately following major meals) is more effective than a raft of smaller particles (prior to such meals) in preventing flux of large particles to the duodenum.

Animal Feed↗
PubMed1989

Revising diagnosis-related groups for neonates.

Groups of neonates who are usually treated at hospitals that provide specialized pediatric care are not adequately classified by the use of diagnosis-related groups (DRGs). Therefore, a set of revised DRGs, pediatric modified DRGs (PM-DRGs), have been developed. Use of PM-DRGs substantially improves the classification of neonates in the following ways: a single pediatric modified major diagnostic category has been defined to include only and all neonates (patients younger than 29 days of age when admitted to the hospital); deaths and transfers of newborns are no longer combined into a single group; birth weight (rather than diagnosis) is used as the primary variable to differentiate categories of neonates; and duration of mechanical ventilation, presence of major problems, and surgery are used to define specific PM-DRGs. A total of 46 PM-DRGs have been developed to replace the 7 DRGs for neonates. Based on a sample of discharged patients from 13 children's hospitals, the overall variance reduction in duration of stay for neonates using PM-DRGs was 38.7% compared with 20.4% for DRGs. Variance reduction for PM-DRGs was 45.9% compared with 16.3% for DRGs when operating cost per case was used instead of duration of stay. After removing outliers at 150 days, the duration of stay variance reduction was 53.3% vs 23.6%, respectively, and the operating cost variance reduction was 58.8% vs 17.8%, respectively.

Birth Weight↗
PubMed1989

Some generalized stochastic compartment models for digesta flow.

Digesta flow models have been based on linear compartment theory that assumes exponential retention times, and on a generalized theory that incorporates nonexponential (Erlang) retention times (Matis, 1987, Journal of Theoretical Biology 124, 371-376). This paper develops a new family of passage models for heterogeneous digesta by mixing the previous models with assumed parametric, usually gamma, mixing distributions. The utility of the resulting models is demonstrated with experimental data on two treatments, namely a chopped and a ground straw, given to each of four cows. Treatment differences are apparent in the preferred model form and in the means of the estimated mean residence times. The models are relatively easy to fit to data using standard estimation procedures, and they should have broad application to other compartment modeling problems with "heterogeneous particles."

Animals↗
PubMed1988

Compartment models for estimating attributes of digesta flow in cattle.

1. The basic assumptions involved in one- and two-compartment models with age-independent distributed residence times (exponential, G1) for describing digesta flow are reviewed as the bases for describing families of one- and two-compartment models which assume age-dependent distributions (Gn) of residence times. 2. The two-compartment, age-independent model with exponentially distributed residence times (G1G1) yielded estimates of essentially equal rate parameters when fitted to faecal values for all four cows receiving a diet of 500 g coarsely chopped, sodium hydroxide-treated straw/kg and one of four cows receiving the same diet but with ground and pelleted straw. The incorporation of progressively higher orders of age dependency (G2-G6, Gn) into the faster turnover compartment of two-compartment models (GnG1) resulted in a resolution of equal rate parameters estimated by the G1G1 model and a reduction in standard errors for the rate and the initial concentration parameters. 3. The occurrence of equal rate parameters in two-compartment models indicated an age-dependent process; a process which could equally well be described by a one-compartment, age-dependent compartment having an order of age dependency equal to the sum of these orders in the two-compartment model with equal rate parameters. 4. The age-independent models overestimated time of first appearance in the faeces of a meal's particles. The association of age dependency with the faster turnover compartment resulted in earlier estimates for first appearance of the marked particles; estimates which were more consistent with observed first appearance. 5. The faecal excretion pattern from cows fed on the ground and pelleted straw diet exhibited an age-independent distribution of longer residence times which dominated approximately 80% of the later residence times. Age-dependent, one-compartment models gave a poor fit to such data from these cows fed on ground and pelleted straw. In contrast, age-dependent, one-compartment models provided an excellent fit to data from cows fed on chopped straw; data which indicated that age-independent distributions of residence times were much delayed in appearing or were totally absent. 6. The mean residence time for the slower turnover, age-independent compartment estimated from faecal excretional of stained particles from either diet was similar to that estimated from duodenal concentrations of the stained particles. This suggests that the slower turnover model compartment was confined to preduodenal sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1988

Site and extent of neutral detergent fiber digestion, efficiency of ruminal digesta flux and fecal output as related to variations in voluntary intake and chewing behavior in heifers.

Six heifers (1/4 Brahman x 1/4 Jersey x 1/2 Angus, 290 kg avg wt) with ruminal, duodenal and ileal cannulas were given ad libitum access to a corn silage-based diet with or without 100 mg monensin.hd-1.d-1 in a two-period crossover design. There was no significant effect of monensin on voluntary intake (VI), flow of NDF to the abomasum, fecal output or the efficiency of transfer of NDF to the duodenum (unitary fluxes of NDF through the reticulo-omasal orifice, number.g NDF.(kg BW.75)-1). Monensin increased extent of NDF digestion (NDFD) in the dorsal (P = .07) and ventral (P = .09) ruminal sac. As a fraction of the total tract NDFD, NDFD increased progressively in dorsal rumen (.214), ventral rumen (.548) and duodenal (.818) sites. The VI among individual heifers was negatively related to unitary fluxes of NDF through the reticulo-omasal orifice (P = .001) and to the extent of digestion of potentially digestible NDF (PDNDFD) in the ventral rumen (P = .006) and duodenum (P = .032), but not in the dorsal rumen (P = .720) or in the total tract (P = .785). Fecal output of NDF was negatively related to unitary times of eating (P = .027), ruminating (P = .001), masticating (P = .001) and unitary number of rumination boli (P = .001). These relationships all were influenced (P = .001) by individual heifer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Markers for estimating digesta flow in pigs and the effects of dietary fiber.

Effects of diluting the energy content of a corn-soybean meal diet with either alfalfa meal or corn cobs on nutrient digestibility and rate of passage of feed residues and particle markers were measured in crossbred (Yorkshire X Landrace X Chester White X Large White) barrows with a mean body weight of about 80 kg. The excretion pattern in the feces of Cr-mordanted diet and of rare earths initially bound individually to the mixed diet or to the corn or soybean meal suggested a model having a single age-dependent compartment with time delay. The compartmental turnover rate parameter (lambda 1) estimated by this model did not differ for the rare earths individually used to mark the corn-soybean meal diet (Yb), the corn (La) or the soybean meal (Sm). In contrast, lambda 1 for Cr was smaller (P less than .001) than that of the mean for the three rare earths. The residence time due to displacement flow (tau) did not differ among markers. These results were interpreted to indicate that the high specific gravity of Cr-mordanted feed slowed flow due to mixing but not due to displacement. Correlations between lambda 1 and tau were less than .71. These results suggested that the flow of rare earths initially bound to feed ingredients provides a reasonable estimate of the flow of their undigested residues through the gastrointestinal tracts of nonruminant animals. Inclusion of the fibrous feeds reduced digestibility of dry matter, cell contents, crude protein and acid detergent lignin and increased digestibility of cell walls, cellulose and acid detergent fiber. Digestibilities of cellulose and acid detergent fiber were greater with alfalfa than with corn cobs as the fiber source. Differences in digestibility of crude protein and acid detergent fiber existed due to litter in one replicate of the experiment. Variation in digestibility was not significantly related to variation in lambda 1 or tau within or among treatments and litters. This suggests that variations in lambda 1 and tau were not important causes of the observed variation in digestibility.

Animal Feed↗
PubMed1979

Quantitating ruminal turnover.

Basic principles of in vivo kinetics are reviewed as they apply to the digestive process in ruminants. Emphasis is on application and limitations of techniques for measuring ruminal turnover of undigested feed residues. This turnover can best be measured by using feed particles whose organic constituent(s) contain uniform concentrations of an isotope. Alternatively, rare earths remain attached to feed residues throughout the digestive tract and can also be used. Appropriate application of mathematical methods must consider ingestaflow as a multicompartment process.

Animals↗