Ingesta Contamination Research Articles

Quantification of ractopamine residues on and in beef digestive tract tissues

Ractopamine hydrochloride is a commercial beta-adrenergic agonist commonly used as a dietary supplement in cattle production for improved feed efficiency and growth promotion. Currently, regulatory target tissues (as approved in the New Animal Drug Application with Food and Drug Administration) for ractopamine residue testing are muscle and liver. However, other tissues have recently been subjected to testing in some export markets for U.S. beef, a clear disregard for scientific maximum residue limits associated with specific tissues. The overall goal of this study was to develop and validate an LC-MS/MS assay to determine whether detectable and quantifiable levels of ractopamine in digestive tract-derived edible offal items (i.e., abomasum, omasum, small intestine, and reticulum) of cattle resulted from tissue residues or residual ingesta contamination of exposed surfaces of tissues (rinsates). Tissue samples and corresponding rinsates from 10 animals were analyzed for parent and total ractopamine (tissue samples only). The lower limit of quantitation was between 0.03 and 0.66 ppb depending on the tissue type, and all tissue and rinsate samples tested had quantifiable concentrations of ractopamine. The highest concentrations of tissue-specific ractopamine metabolism (represented by higher total vs. parent ractopamine levels) were observed in liver and small intestine. Contamination from residual ingesta (represented by detectable ractopamine in rinsate samples) was only detected in small intestine, with a measured mean concentration of 19.72 ppb (±12.24 ppb). Taken together, these results underscore the importance of the production process and suggest that improvements may be needed to reduce the likelihood of contamination from residual ractopamine in digestive tract-derived edible offal tissues for market.

The development of chlorophyll-based markers in poultry diets to aid detection of fluorescent fecal contamination

Incidents of foodborne illness associated with consuming undercooked or raw chicken are often linked to 2 causative pathogens: Campylobacter spp. or Salmonella spp. Numerous studies have shown that contamination of carcasses results when pathogens are transferred from the intestinal tract or fecal material on feet and feathers to the dressed carcass.Ultraviolet spectral imaging to detect surface fecal and ingesta contamination on poultry carcasses may provide a solution to aid detection. However, poultry diets do not provide sufficiently high levels of natural fluorophores for this system to be reliable. This study investigated the potential of chlorophyll-based feed additives to improve fluorescence of the feces and narrow the excitation and emission wavelengths to aid in the development of a simple visualization system. Twenty-four hens (Gallus gallus domesticus) were allocated at random to 1 of 4 treatments: control (C, no marker), Zn chlorophyllin, Mg chlorophyllin, or Fe chlorophyllin. All markers were incorporated into mash before pelleting at a rate of 1 g/kg of DM. The experiment consisted of two 4 × 4 Latin squares with each period consisting of 2 wk. Feces were collected and extracted in acetone:water (50:50; vol/vol) with fecal fluorescence emission spectra determined using a Jasco FP-6200 Spectrofluorometer with excitation at 382 nm. A main peak evolved at wavelength 670 nm with the total area under the peak used as fluorescence intensity. Following 7 d of marker supplementation, the 3 markers improved the fluorescence intensity by ×14.8, 12.8, and 6.9 for Fe, Mg, and Zn chlorophyllin, respectively, compared with the control. The addition of feces containing Mg chlorophyllin to chicken carcass increased detection of the feces compared with feces with no marker. Also, due to the plain background of chicken skin, a simple image at 675 nm with appropriate thresholds would allow detection of contaminated carcasses at the current slaughter line speed without the need of expensive hyperspectral imaging.

A meat control system achieving significant reduction of visible faecal and ingesta contamination of cattle, lamb and swine carcasses at Swedish slaughterhouses

The aim of this study is to describe how unsatisfying slaughter hygiene was identified by monitoring of visible carcass contamination, and to review the effectiveness of subsequent official control measures. In 2007, a survey of visible faecal and ingesta carcass contamination was performed by National Food Agency staff at, respectively, 14, 9 and 11 of the largest Swedish slaughterhouses for cattle, lamb and swine. The results revealed that large percentages of beef and lamb carcasses were visibly contaminated and a new control system was introduced in 2008. Data from regular official control collected in 2011, at, respectively, 14, 8 and 12 of the largest slaughterhouses for cattle, lamb and swine show that the general level of cattle and lamb carcasses contamination was significantly lower than in 2007. The median percentage of visibly contaminated carcasses had decreased from 10% (beef) and 13% (lamb) in 2007, to 0% for both species in 2011. For swine, the level of visibly contaminated carcasses was relatively low already in 2007 (median 2%), but tended to be even lower in 2011. According to local official control coordinators, the operators primarily achieved the reduction in contamination of carcasses through improving their own verifying control, trimming, slaughter hygiene and education of personnel. Among the measures taken by the National Food Agency, the enforcement of regular official control and communication with operators was listed as important measures at all slaughterhouses, and sanctions (civil penalty, or consideration of civil penalty) at some slaughterhouses. This study shows how measures taken by the competent authority can lead to substantial reductions in visible carcass contamination.

Line-scan hyperspectral imaging for real-time in-line poultry fecal detection

The ARS multispectral imaging system with three-band common aperture camera was able to inspect fecal contaminants in real-time mode during poultry pro- cessing. Recent study has demonstrated several image processing methods including binning, cuticle removal filter, median filter, and morphological analysis in real-time mode could remove most false positive errors. The ARS research groups (Beltsville, MD and Athens, GA) and their industry partner are now merging the fecal detection and systemically disease detection systems onto a common platform using a line-scan hyperspectral imaging system. This system will aid in commercialization by creating one hyperspectral imaging system with user-defined wavelengths that can be installed at different locations of the processing line to solve significant food safety prob- lems of disease as well as contaminant detection. Thus, this research demonstrated the feasibility of line-scan hyper- spectral imaging system in terms of processing speed and detection accuracy for a real-time, in-line fecal detection at current processing speed (at least 140 birds per min) of commercial poultry plant. Our preliminary results showed the real-time hyperspectral imaging system could detect small amount (about 10 mg) of fecal (duodenum, cecum, colon) and ingesta contaminants. The system performance could be improved by optimizing line lighting system especially near-infrared bands for quality images and additional spectral images to minimize false positive detection errors. The newly developed line-scan hyper- spectral imaging system could improve Food Safety Inspection Service (FSIS)'s poultry safety inspection pro- gram significantly.

Detection of Fecal/Ingesta Contaminants on Poultry Processing Equipment Surfaces by Visible and Near-Infrared Reflectance Spectroscopy

Visible and near-infrared (NIR) spectra and samples for laboratory microbial analysis were acquired of fecal contaminants, ingesta contaminants, and bare processing equipment surfaces (rubber and stainless steel) in a commercial poultry processing plant. Spectra were analyzed in the visible region of 450 to 748 nm and the NIR region of 920 to 1680 nm and microbial sampling for Enterobacteriaceae counts (EBC) was conducted for 82 fecal contaminant samples, 59 ingesta contaminant samples, 40 bare rubber belt areas, and 40 bare stainless steel areas. Two-wavelength band ratios in the visible and NIR regions were selected for separating contaminants from equipment areas. Principal component analysis (PCA) was performed to analyze the spectral data set and 2-class soft independent modeling of class analogy (SIMCA) models were developed for comparison with band ratio classification. Fecal and ingesta contaminants were difficult to separate from each other but both were easily differentiated from the equipment areas. The visible ratio using 518 and 576 nm correctly classified 100% of contaminant samples and 92.5% of equipment area samples. The NIR ratio using 1565 and 1645 nm correctly classified 100% of the contaminant samples and 95% of the equipment area samples. Microbiological analysis found the highest EBC levels for fecal contaminants; mean EBC for ingesta contaminants was significantly lower than that for fecal contaminants. The high EBC levels for fecal contaminants indicate that these contaminants should be targeted for spectral-based detection methods for sanitation monitoring and verification purposes; although their EBC levels are significantly lower, ingesta contaminants should also be included due to difficulty of separation from fecal contaminants.

Effect of an Organic Acid Product During Feed Withdrawal on Broiler Mortality, Shrinkage and Carcass Condemnation Following Transport to Processing

In poultry and other species, economic losses during transport are due to mortality, carcass shrinkage (carcass dehydration) and carcass condemnation. Feed Withdrawal (FW) prior to processing is necessary to reduce fecal ingesta contamination of carcasses during processing. Direct acidification of the water with specific concentrations of some Organic Acids (OA) has been shown to significantly reduce the amount of potential pathogens such as Salmonella on the carcasses by antemortem disinfection of th e crops when used during the pre-slaughter feed withdrawal period. However, reduced water consumption due to effective OA concentrations have been shown to increase carcass shrink. In the present study, the effect of a commercially available mix of flavored organic acids significantly reduced carcass condemnation at the processing plant in 3/3 trials (p<0.05) % and mortality during transportation in 1/3 trials (0.40% treated vs. 0.65% control). A consistent improvement of average body weights at the farm and at the processing plant due to reduction of carcass shrinkage and condemnation at the processing plant were also observed in the treated marked age broiler chickens. Water intake was numerically higher in treated birds when compared with non-treated birds (72.9 mL vs. 62.5 mL). During FW, this OA product could be useful to reduce mortality, shrinkage and carcass condemnation during transportation to the processing plant of broiler chickens.

Contaminant Classification of Poultry Hyperspectral Imagery using a Spectral Angle Mapper Algorithm

Since hyperspectral imaging technique has been demonstrated to be a potential tool for poultry safety inspection, particularly faecal contamination, a hyperspectral image classification method was developed for identifying the type and source of faecal contaminants. Spectral angle mapper (SAM) supervised classification method for hyperspectral poultry imagery was performed for classifying faecal and ingesta contaminants on the surface of broiler carcasses. Spatially averaged spectra of three different faeces from the duodenum, caecum, colons, and ingesta of maize/soya bean diet were used for classification data. The SAM classifier using reflectance of hyperspectral data with 512 narrow bands from 400 to 900 nm was able to classify three different faeces and ingesta on the surface of poultry carcasses. Based on the comparison with ground truth region of interest, both classification accuracy and kappa coefficient, which quantifies the agreement of classification, increased when spectral angle increased. The overall mean accuracy and corresponding mean kappa coefficient to classify faecal and ingesta contaminants were 90·13% (standard deviation of 5·40%) and 0·8841 (standard deviation of 0·0629) when a spectral angle of 0·3 radians was used as a threshold.

Effect of reduced lairage duration on beef quality

A study involving two groups of feedlot cattle (n = 84 and 112) was undertaken to compare the effect of two preslaughter lairage (L) durations (3 h v. 18 h) on carcass and meat quality properties. The cattle were grainfed for 150 days before slaughter and had a mean carcass weight of 347.0 ± 25.4 kg. Cattle from the same feedlot pen were randomly allocated to the two treatments on the day before slaughter. One group was transported to the abattoir the day before slaughter and held overnight (L–18 h) whereas the other group remained at the feedlot and was transported the following morning and remained in the lairage for 3 h before slaughter (L–3 h). After slaughter, meat quality was evaluated on a subset of 15 carcasses/lairage treatment from the two slaughter groups. Objective meat quality measures were made on unaged and 14-day-aged striploins (longissimus lumborum) from these carcasses. Cattle from the reduced lairage treatment had heavier bled bodyweights at slaughter (P &lt; 0.05) but there was no effect (P &gt; 0.05) on carcass weight, muscle glycogen concentration, pH3h, ultimate pH, shear force or Minolta lightness values. Significant interactions (P &lt; 0.05) between lairage duration and aging were observed for cooking loss percentage and Minolta a* and b* values but these were relatively small in magnitude. There were no differences in the incidence of ingesta contamination or rumen rupture between the lairage treatments. It was concluded that shortening holding times in lairage from 18 to 3 h for cattle that have travelled &lt;6 h would not affect carcass or beef quality.

On-line real time aid to the verification of CCP compliance in beef slaughter HACCP systems

This study investigated the use of an on-line monitoring and display system in a beef slaughtering plant. The objective was to determine what information was possible and what benefits could be forthcoming that would assist compliance with HACCP requirements. The system was to be low tech, user friendly and economical. The study was carried out over eleven days, spread over 13 weeks; 75 cattle were observed each day for visible faecal, rumen and ingesta contamination over six sites per carcass side. Spinal cord presence in the exposed spinal channel was also observed. Over the course of the study the number of carcasses with visible contaminated was reduced from 76% to 33.33%; visible contamination attributed to dehiding operations was reduced from 54.67% to 24.00%, visible contamination attributed to evisceration operations was reduced from 44% to 16.67%. A significant reduction in the magnitude of visible contamination per carcass was also observed. Spinal cord presence was reduced from 6% to 0%. The system facilitated the identification of the most probable causative process stages, the implementation of on-line real time immediate and long term corrective action and the establishment of a single process CCP.

Performance of Supervised Classification Algorithms of Hyperspectral Imagery for Identifying Fecal and Ingesta Contaminants

In order to select the optimum classifier, the performance of six different supervised classification algorithms including parallelepiped, minimum distance, Mahalanobis distance, maximum likelihood, spectral angle mapper, and binary coding were investigated and compared for identifying fecal and ingesta contaminants in hyperspectral poultry imagery. A pushbroom line-scan hyperspectral imager was used for hyperspectral image acquisition, with 512 narrow bands between 400 and 900 nm wavelengths. Three different feces from digestive tracts (duodenum, ceca, colon) and ingesta were considered as contaminants. These contaminants were collected from broiler carcasses that had been fed a mixture of corn, milo, or wheat with soybean. The classification accuracies varied from 62.9% to 92.3% depending on the classification method. The highest classification accuracy for identifying contaminants from corn-fed carcasses was 92.3% with a spectral angle mapper classifier. The accuracy was 82.1% with the maximum likelihood method for milo-fed carcasses, and 91.2% accuracy was obtained for wheat-fed carcasses when the same classification method was employed. The mean classification accuracy for classifying fecal and ingesta contaminants obtained in this study was 90.3%.

Prevalence and Numbers of Bacteria in Broiler Crop and Gizzard Contents

Crops or gizzards in broiler carcasses are frequently damaged during processing. The contents from either organ, defined by the USDA Food Safety and Inspection Service as ingesta, may contaminate the carcass. Previous research has shown crop contents are a source of Salmonella contamination on processed carcasses, although less information is available on gizzard contents. The purpose of this study was to determine the prevalence and numbers of total aerobic bacteria, coliforms, Escherichia coli, and Campylobacter in ingesta collected from the crop and gizzard. In each of 3 replicate trials, 10 uneviscerated broiler carcasses were obtained from a processor at the shackle transfer point just prior to evisceration. Liquid crop contents and solid gizzard contents were aseptically collected from each carcass and quantitatively cultured. Total aerobic bacteria, coliforms, E. coli, and Campylobacter were determined for contents from both organs. Crop contents (log cfu/mL), compared with gizzard contents (log cfu/g), contained significantly (P < 0.05) higher numbers of total aerobic bacteria (5.6 vs. 2.9), coliforms (4.2 vs. 2.3), E. coli (3.9 vs. 2.2), and Campylobacter (4.6 vs. 2.2). Escherichia coli prevalence was higher in crop samples (28 of 29) than gizzard samples (19 of 30). Campylobacter prevalence was also higher for crop vs. gizzard samples (29 of 29 vs. 12 of 30). An average of 2.4 g of crop contents and 8.4 g of gizzard contents were recovered. Crop contents contain more bacteria than gizzard contents and contained a higher incidence of E. coli and Campylobacter contamination. However, because of the numbers of bacteria and amount of material in the crop and gizzard, it is unlikely that ingesta contamination would increase overall bacterial counts of prechill broiler carcasses.

Detection of Ingesta on Pre-Chilled Broiler Carcasses by Hyperspectral Imaging

The contents of the upper digestive tract (i.e. crop, proventriculus and gizzard) may serve as a source of carcass contamination during broiler processing. The crop as been identified as a source of Salmonella and Campylobacter on contaminated carcasses and is more likely to rupture than the ceca during commercial evisceration. The objective of this study was to determine the effectiveness of hyperspectral imaging for detecting ingesta contamination spots varying in mass from the crop and gizzard. Pre-chilled broiler carcasses were collected from a commercial processing plant. Crop and gizzard contents were also aseptically collected and enumerated for Campylobacter, coliforms, E. coli and total aerobic bacteria. Broiler carcasses were imaged and then contaminated with a spot of known mass (10, 50, or 100 mg) of crop or gizzard contents. Carcasses were then re-imaged. The imaging system correctly detected 100% of the crop and gizzard contents regardless of the mass or spot size. However, not every pixel associated with a given spot (contaminant ground truth) was detected. Detection of crop and gizzard content contaminant ground truth pixels averaged 72 and 53%, respectively. The mean number of bacteria in the crop contents were as follows: E. coli 4.0 log, coliforms 4.1 log, and total aerobic bacteria 5.7 log CFU/g of crop contents. Crop contents in the current study were Campylobacter negative. Applying crop contents in the amounts of about 9, 54, and 231 mg resulted in significant (P<0.05) increases in all bacterial population measured, with the biggest increase being noted for total aerobic bacteria. Gizzard contents contained only 4.6 log CFU/g of total aerobic bacteria. The total added bacterial load from contamination with known amounts of crop and gizzard contents did not significantly increase whole carcass counts of all bacteria enumerated. Based on these counts and numbers of bacteria found in gizzard, carcass contamination with visible ingesta does not appear to significantly increase bacterial load.

Performance of hyperspectral imaging system for poultry surface fecal contaminant detection

A hyperspectral imaging system demonstrated potential to detect surface fecal and ingesta contaminants on poultry carcasses. Hyperspectral imagery were processed and analyzed with four pre-processing methods considering calibration and spectral smoothing approaches. A band-ratio image processing algorithm, using 2-wavelengths ( I 565/ I 517) and 3-wavelengths ( I 576 − I 616)/( I 529 − I 616) equations, was then applied for each pre-processed method that included background masking for ratioed images, and fecal thresholding. Based on a high accuracy of 96.2% for predicting surface contaminants and significantly less false positives on the 64 birds measured, the method with calibrated and smoothed images was the best pre-processing method for fecal and ingesta contaminant detection. In conjunction with appropriate image processing algorithms, the hyperspectral imaging system is an effective technique for identifying fecal and ingesta contaminants on broiler carcasses. Specifically, band-ratio with 2-wavelength equation ( I 565/ I 517) performed very well with 96.4% accuracy and 147 false positives for detecting both feces (duodenum, ceca, colon) and ingesta contaminants.

MULTISPECTRAL IMAGING SYSTEM FOR FECAL AND INGESTA DETECTION ON POULTRY CARCASSES

ABSTRACT A multispectral imaging system, including a common aperture camera with three optical trim filters (515.4, 566.4 and 631 nm), which were selected by visible/near‐infrared NIR spectroscopy and validated by a hyperspectral imaging system, was developed for a real‐time, on‐line poultry inspection application. The algorithm developed by a hyperspectral imaging system was employed for multispectral image analysis to validate the accuracy of fecal and ingesta detection in real‐time poultry processing. A multispectral imaging system could be used effectively for detecting feces (from duodenum, ceca, and colon) and ingesta on the surface of poultry carcasses with the processing time of approximately 251 ms or 3.99 frames/s. The multispectral imaging system developed in this research can be used for real‐time, on‐line detection of fecal and ingesta contaminant on poultry carcasses. The overall accuracy to identify fecal and ingesta contaminants was 96.8% and the prediction accuracy to identify each contaminant were 92.4% for duodenum and 98% for ceca, colon, and ingesta with moderate false positives.

A Hyperspectral Imaging System for Identification of Faecal and Ingesta Contamination on Poultry Carcasses

A method and system for detecting faecal and ingesta contaminants on poultry carcasses were demonstrated. A visible/near infrared monochromator, which measured reflectance and principal component analysis were first used to identify key wavelengths from faecal and uncontaminated skin samples. Measurements at 434, 517, 565 and 628 nm were identified and used for evaluation with a hyperspectral imaging system. The hyperspectral imaging system, which was a line-scan (pushbroom) imaging system, consisted of a hyperspectral camera, fibre-optic line lights, a computer and frame grabber. The hyperspectral imaging camera consisted of a high-resolution charge coupled device (CCD) camera, a prism-grating-prism spectrograph, focusing lens, associated optical hardware and a motorised controller. The imaging system operated from about 400 to 900 nm. The hyperspectral imaging system was calibrated for wavelength, distance and percent reflectance and analysis of calibrated images at the key wavelengths indicated that single-wavelength images were inadequate for detecting contaminants. However, a ratio of images at two of the key wavelengths was able to identify faecal and ingesta contaminants. Specifically, the ratio of the 565-nm image divided by the 517-nm image produced good results. The ratio image was then further processed by masking the background and either enhancing the image contrast with a non-linear histogram stretch, or applying a faecal threshold. The results indicated that, for the limited sample population, more than 96% of the contaminants were detected. Thus, the hyperspectral imaging system was able to detect contaminants and showed feasibility, but was too slow for real-time on-line processing. Therefore, a multivariate system operating at 565 and 517 nm, which should be capable of operating at real-time on-line processing speed, should be used. Further research with such a system needs to be conducted.

Visible Ingesta on Prechill Carcasses Does Not Affect the Microbiological Quality of Broiler Carcasses after Immersion Chilling

Microbiological quality of broiler carcasses, with or without visible ingesta contamination, was compared at pre- and postimmersion chilling sites. A total of 1,080 carcasses was sampled in seven commercial processing plants and analyzed for aerobic bacteria (aerobic plate count; APC), Escherichia coli and Campylobacter spp. counts (log10 cfu/mL), and incidence of Salmonella based on USDA approved microbiological procedures.In all plants, the APC (4.22 vs. 3.27), E. coli (2.36 vs. 1.22) and Campylobacter spp. (1.69 vs. 0.83) counts (log10 cfu/mL), and Salmonella incidence (20.7 vs. 5.7%) were significantly (P < 0.05) higher on pre- vs. postimmersion chill carcasses, respectively. Microbial load on carcasses collected from pre- and postimmersion chill sites differed significantly among the plants in this study. However, there were no statistically detectable differences (P > 0.05) in microbial counts between carcasses with or without visible contamination at both sampling sites. Overall, immersion chilling resulted in about a 1-log reduction in microbial load on carcasses, compared to prechill levels. These results demonstrate the lack of a direct correlation between the presence of visible ingesta and microbial contamination on poultry carcasses.

HYPERSPECTRAL IMAGING FOR DETECTING FECAL AND INGESTA CONTAMINANTS ON POULTRY CARCASSES

A hyperspectral imaging system including a camera with prismgratingprism spectrograph, fiber optic linelighting, motorized lens control, and hyperspectral imageprocessing software was developed for poultry safety inspection,particularly identification of fecal and ingesta contamination on poultry carcasses. Both spectral and spatial image databetween 400 and 900 nm with 512 spectral bands were acquired from fecal and ingesta contaminated poultry carcasses. Fourdominant wavelengths (434, 517, 565, and 628 nm) were selected by principal component analysis from visible/nearinfraredspectroscopy for wavelength selection of hyperspectral images. A calibration model for the hyperspectral imaging systemwas developed from calibration lighting sources (HgAr, Kr, and lasers) for accurate band selection from the hyperspectralimages to identify spatial and spectral characterization of fecal and ingesta contaminants. Hyperspectral image processingalgorithms, specifically band ratio of dualwavelength (565/517) images and histogram stretching, were effective in theidentification of fecal and ingesta contamination of poultry carcasses. Test results indicated that the detection accuracy was97.3% for linear and 100% for nonlinear histogram stretching. This article presents the research results that hyperspectralimaging can be used effectively for detecting feces (from the duodenum, ceca, and colon) and ingesta on poultry carcassesand demonstrates the potential application for online safety inspection of poultry.

Steady-state and time-resolved spectroscopy of F420 extracted from methanogen cells and its utility as a marker for fecal contamination.

Methanogenic bacteria, which are common inhabitants of the animal digestive tract, contain the fluorescent compound F420 (coenzyme 420), a 7,8-didemethyl-8-hydroxy-5-deazariboflavin chromophore. F420 was characterized as an initial step in determining if this compound would be useful as a fluorescent marker for the detection of fecal and ingesta contamination. Using a single anion exchange chromatographic process, F420 was separated from other cell components of a Methanobrevibacter sp. cell culture. The extent of separation was determined spectroscopically. To aid in the development of possible techniques for the detection of fecal contamination using F420 as a marker, further spectroscopic investigation of F420 was conducted using steady-state and time-resolved fluorescence methods. The fluorescence lifetime of F420 in an elution buffer of pH 7.5 was found to be 4.2 ns. At higher pH values, the fluorescence decay, F(t), was best described by a sum of two exponentials: at pH 13, F(t) = 0.31 exp(-t/4.20 ns) + 0.69 exp(-t/1.79 ns). Further investigation using front-faced fluorescence techniques has shown that emission from F420 can be collected efficiently from samples of methanogen cell cultures as well as from fecal material.

Cattle handling at abattoirs. 3. The effects of feeding, and of different feeds, during the resting period before slaughter on liveweight carcasses and muscle properties

The effects of feeding lucerne hay or rice straw during the resting period before slaughter on live, carcass and liver weights, bruising, the percentages of condemned head and tongues and of rumens with ingesta spillage, and muscle properties of cattle were examined. The 217 British breed and 70 Brahman steers (mean liveweights of 582 and 603 kg) had been grazing native pastures in northern Queensland. They were transported 440 km by road to an abattoir.The seven groups (each 41 steers) had access to water from unloading at the abattoir (late day 2) until slaughter. Three groups (N2, N4 and N6) were not fed, while two groups were fed ad libitum rice straw (RS4 and RS6) and another two groups were fed ad libitum lucerne hay (LH4 and LH6) from day 3 until 24 h before slaughter. The period from mustering to slaughter was 2 days for group N2,4 days for groups N4, RS4 and LH4, and 6 days for N6, RS6 and LH6.Unfed steers lost 4.7% of their pre-transport liveweight after 3 days and 9.1% after 5 days, while the fed steers lost 34% and 6.7%, respectively.Group N2 had a heavier (P&lt;O.05) mean carcass weight than groups N4, RS4, RS6 and LH6 (351 kg compared with 343-344 kg). Both N2 and LH4 (348 kg) were heavier (P&lt; 0.05) than group N6 (340 kg). Trends in mean dressing percentage were the same as for carcass weight. Group N2 had a heavier (P&lt; 0.05) mean liver weight than all other groups, with no effect of feeding treatment. Group N2 and the fed groups (except RS6) had a greater (P&lt; 0.05) mean water content for the M. longus colli than groups N4 and N6.Treatment had no significant effect on mean bruise score, fat thickness, mean pH value of M. longissirnus dorsi 24 h post mortem, the percentage of carcasses with high (&gt;6.00) pH values, and the percentages of heads and tongue condemned due to ingesta contamination and rumens contaminated with ingesta spillage.