Effects of ingestive mastication on particle dimensions and weight distribution of coastal bermudagrass hay fed to steers at four levels.

Coastal bermudagrass (Cynodon dactylon [L.] Pers.) hay was fed in the long form to four ruminally cannulated steers to evaluate the effects of intake level on the physical reduction of feed particles during ingestive mastication. The experimental design was a 4 x 4 latin square with 18-d periods. Treatments based on previous intakes were set at 50, 70, 90 and 110% of feed consumed per animal and fed at 12-h intervals. Boli of ingested, masticated hay were collected at the cardia and separated by wet-sieving into fragments retained on sieves of .0027 to 4.0 mm (mesh aperture). In addition, particles retained on the 4.0-mm and 2.0-mm sieves were scanned by image analysis. Ingestive mastication resulted in a linear decrease (P less than .05) in the proportion of boli particles retained on the top (4.0-mm) sieve and linear increases on the 2.0- (P less than .02), 1.0- (P less than .06) and .25-mm (P less than .06) sieves with increasing level of intake. Sixteen to 21% of the ingested hay particles passed through a 1.0-mm sieve. Mean particle size, as determined by sieving data, decreased linearly (P less than .05) as feeding level increased. Image analysis showed no differences in length (L) or width (W) of particles retained on the 4.0- and 2.0-mm sieves as feeding level increased, but L/W decreased linearly (P less than .05) on both sieves. The frequency of jaw movements following feeding was very similar across feeding levels and averaged 71.3 chews/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Eating and ruminating behavior of steers fed Coastal Bermudagrass hay at four levels.

Effects of feeding level on chewing behavior and physical reduction of particles during ingestive mastication and rumination were examined in four ruminally cannulated steers fed Coastal bermudagrass (Cynodon dactylon [L.] Pers.) hay in the long form. The experimental design was a 4 x 4 latin square with 18-d periods. Treatments based on previous intakes were set at 50, 70, 90 and 110% of feed consumed per animal. Steers were fed at 12-h intervals. Chewing behavior was monitored over 4 d with a computerized system. Boli of ingested, masticated hay (MH), collected at the cardia, and serial samples of digesta taken from the ruminal upper strata (RUS) were wet-sieved. Dimensions of MH particles retained on 4.0- and 2.0-mm sieves were determined by image analysis. Increasing feeding level resulted in a linear increase in the number of boli ruminated (P less than .01) and in linear increases in eating (P less than .01), ruminating (P less than .05) and total chewing time (P less than .01). Linear increases in number of eating (P less than .01), ruminating (P less than .01) and total chews (P less than .01) also were observed. Feeding level had no effect on bolus duration, number of chews/bolus, number of boli/min rumination time and number of chews/min rumination time. The extent of particle breakdown during ingestive mastication was a determinant of the number of boli ruminated daily and their associated number of chews. Number of boli ruminated daily also was related to the RUS mean particle size. Eating time did not provide a reliable indication of how well feed was chewed.(ABSTRACT TRUNCATED AT 250 WORDS)

A BASIC-language program for dedicated energy-dispersive microanalysis of thin samples in TEM or STEM.

The program QTHIN combines those methods for processing energy-dispersive X-ray spectra and computing concentrations best suited to thin section microanalysis in TEM or STEM. The program is in BASIC, and so can be modified (for instance for unusual geometries, other matrices such as oxides, etc.). It is suitable for routine use on complex samples with peak overlaps, and for "not-so-thin" samples in which absorption is not negligible.

Volume determination of TEM specimens containing particles or precipitates.

The volume of thin foil specimens, which contain precipitate or other particles, viewed in the TEM is needed to determine particle density and spacing. It can be determined from the locations of the particles, measured using stereo pairs. A calculation that determines the volume between planes (not necessarily parallel or horizontal) that enclose the points is described. These planes will systematically underestimate the actual surface spacing and hence the volume, but a simple correction factor based on the number of points used in the fit can be used to estimate the actual volume. The method is tested, and its accuracy is evaluated using simulated data and applied to precipitate particles in creep-tested silicon carbide.

SEM low magnification stereoscopic technique for mapping surface contours: application to measurement of volume differences in human teeth due to polishing.

SEM stereogrammetry with a low magnification mosaic of pictures is used to measure the elevation of many individual points. This random array of elevations is then connected into a triangular mesh, from which a contour map of elevation is drawn for the entire surface. Maps of surfaces before and after removal of material are used to determine the volume removed. The method is applicable to many circumstances of wear, erosion or deformation of surfaces. It is applied here to the erosion of human teeth due to dental polishing.

A simple electronic device and computer interface system for monitoring chewing behavior of stall-fed ruminant animals.

A simple and low cost electronic switching device interfaced to a microcomputer was developed and utilized to monitor the chewing behavior of stall-fed cattle. The system transforms jaw movements directly into binary notation. The device is attached to a halter and consists of two contact points inserted into a piece of rubber tubing. Elongation of the rubber tubing by the movements of the lower jaw breaks the electrical circuit between the contact points. Every break in the circuit is recorded as a chew by the time-clock-equipped microcomputer, which records animal and time of each chew (nearest second). Data are stored automatically at the end of every hour and later transferred to diskettes for permanent storage and future processing. Use of an interface card allows simultaneous monitoring of up to eight animals. A program was written to separate chewing during eating from chewing during rumination. The system has been used successfully for approximately 2500 steer-h and could be easily adapted to most species of ruminants.