Technical note: A novel technique to assess internal body fat of cattle by using real-time ultrasound.

The objectives of this study were to describe a system to assess KPH fat by using real-time ultrasound (RTU) and to develop equations to predict total physical separable internal fat (IFAT) based on ultrasound measurements. Data for this study were obtained from 24 Angus steers fed either hay- or corn-based diets during the backgrounding phase. Steers were serially slaughtered in 3 groups: at weaning (baseline), then at 4 and 8 mo after weaning. A fourth group was composed of 4 steers from the hay-fed group that were slaughtered at approximately 10 mo after weaning. The RTU measurements were collected every 2 mo, with a preslaughter scan approximately 7 d before the slaughter time. The RTU measurements consisted of 12th- to 13th-rib backfat thickness, 12th to 13th ribeye area, percentage of intramuscular fat, and kidney fat depth, which was measured in a cross-sectional image collected between the first lumbar vertebra and the 13th rib. For kidney fat, the ultrasound probe was placed on the flank region approximately 15 cm from the midline of the animal. Images were stored in the ultrasound console, and measurements were taken between the ventral part of the iliocostalis muscle and the end of the KPH fat at the chute side. The relationship between carcass and ultrasound measurements in the depths of kidney fat (cKFd and uKFd, respectively) had an r(2) of 0.93, with a root mean square error (RMSE) of 1.14 cm. An allometric regression between carcass KPH weight (cKPHwt) and cKFd was identified, and the untransformed regression had an r(2) of 0.96. The linear regression between total IFAT and cKPHwt had an r(2) of 0.97, with an RMSE of 2.67 kg. Therefore, a system was developed to predict IFAT from uKFd measurements by combining these equations. Additionally, a single linear regression between IFAT and uKFd measurements was developed (r(2) = 0.89, RMSE = 5.32 kg). Even though the system of equations had a lower RMSE of prediction and greater r(2) compared with the single linear regression (4.80 vs. 5.10 kg and 0.91 vs. 0.89, respectively), there was no difference between these methods in predicting IFAT (P = 0.4936) by using a pairwise mean square error of prediction analysis. Our results indicated that uKFd measurements can accurately and precisely predict the cKFd of steers consuming either high concentrate or forage rations. The results also showed that cKFd is highly correlated with cKPHwt, which can be used to estimate total IFAT. More research is needed to further evaluate this technique with different feeding strategies, breeds, and sexes.

The effect of milk intake on forage intake and growth of nursing calves.

Thirty-nine Holstein steer calves were assigned to one of five treatments at birth and individually fed for 200 d with milk replacer reconstituted to equal the fat and protein concentration of beef cow milk. Treatment levels were the quantities of reconstituted milk fed per day based on lactation curves, which were based on peak milk levels (PML) of 2.72, 5.44, 8.16, 10.88, and 13.6 kg/d, respectively. In addition to reconstituted milk, chopped alfalfa hay was offered ad libitum to allow for maximal voluntary forage consumption. All calves were fed a high-energy diet postweaning until they reached a similar degree of fatness in the 12th rib (4 to 5% chemical fat) as determined by ultrasound. There were differences (P < 0.05) among groups in weaning weight, preweaning ADG, age, and weight at slaughter. During the preweaning phase, there was a linear relationship (P < 0.01) for daily milk and forage DE intake; however, DE intake per unit of BW did not differ across treatments (P = 0.06). Increasing PML resulted in a linear (P < 0.01) decrease in alfalfa hay intake in the preweaning phase, and G:F increased quadratically (P < 0.01). During the postweaning phase, preweaning milk intake had no meaningful effect on postweaning ADG, but overall ADG had a linear relationship (P < 0.01) with preweaning milk level. There was no effect of PML on the 12th-rib lipid percent, marbling score, or quality grade, but protein and fat concentration in the carcass and empty BW increased linearly (P < 0.01) with PML. The group fed at 2.72 kg/d PML was 58 kg lighter (P = 0.03) and required 34 d more (P < 0.01) to reach the predetermined degree of fatness at slaughter than the group fed at 13.6 kg/d PML, suggesting that increased milk production by the dam can decrease the number of days to the slaughter weight at which a similar rib lipid concentration is reached.

Pork carcass evaluation with an automated and computerized ultrasonic system.

Carcass data were collected from market barrows and gilts (n = 325) slaughtered at a commercial slaughter facility in Canada to estimate carcass composition from longitudinal average fat depth and muscle depth measured automatically by a computerized real-time ultrasonic system. Similar and other ultrasonic measurements were also made manually from the same carcasses for comparison purposes. Results of regression analysis indicated that the optimum measurements were hot carcass weight, automatic average fat depth, and muscle depth made from the carcass longitudinal scans between the 10th rib and last rib in predicting weight of lean (defatted, deboned four lean cuts, R2 = .88, RSD = 1.19) and weight of grade lean (weight of lean plus skinless square-cut belly and side (spare) ribs, R2 = .92, RSD = 1.09). The automatic depth measurements provided more precise factors for estimation of lean than the careful manual measurements of fat depth, muscle depth, and loin muscle area. Manually measured loin muscle area was not required (P > .05) after hot carcass weight, manually measured fat depth, and loin depth were included in the models for predicting weight and percentage of any of the dependent variables. These results suggest that the automated and computerized ultrasonic system tested in this study can be used as an efficient and objective tool in a meat animal value-based marketing system.

Relationships of empty-body composition and fat distribution to live animal and carcass measurements in Bos indicus-Bos taurus crossbred cows.

Empty-body composition and fat distribution were determined for 55 nonpregnant, mature Bos indicus-Bos taurus crossbred cows fed to achieve variation in fatness. Prior to slaughter, cows were condition and frame scored, weighed and measured for hook height, hook width, heart girth and lengths from point of shoulder to pin and hook to pin. Fat thickness at three locations and ribeye area were measured ultrasonically on the live animal and carcass. Quality and yield grades were determined after a 48-h postslaughter chill. Visceral fat was excised at slaughter and weighed. Kidney, heart and pelvic (KHP) fat was excised from one side and the remainder of the side was separated into bone and soft tissue. Soft tissue was subsampled and analyzed for ether extract. Proportions of fat in soft tissue, bone, viscera and KHP were calculated. Variations of percentage of empty-body fat in soft tissue, KHP and bone were explained (R2 greater than .64) by equations involving either live animal or carcass measurements. Both ultrasonic and subjective fat estimates were of importance (P less than .05) in equations predicting fatness, indicating the importance of variation in fat distribution. Factor analysis indicated that fat accretion is a complex entity composed of several distinct distribution patterns (anterior-posterior, internal-external, intramuscular-intermuscular).

Muscle metabolism and real-time ultrasound measurement of muscle and subcutaneous adipose tissue growth in lambs fed diets containing a beta-agonist.

Rambouillet X Finn crossbred wether lambs were evaluated for differences in longissimus muscle cross-sectional area and overlaying subcutaneous adipose tissue thickness resulting from the use of the beta-agonist clenbuterol. Treatment groups received 0 and 2 ppm clenbuterol in the diet for approximately 40 d prior to slaughter. Longissimus muscle cross-sectional area and fat depth over the 12th-13th rib juncture were measured by real-time ultrasound before and during administration of the compound. At slaughter, muscle metabolism in vitro and carcass characteristics were measured. Based on comparisons with an initial-kill group of sheep, longissimus muscle cross-sectional area increased in control sheep by 12% (P greater than .05) over the 40-d experimental period, and increased in clenbuterol-fed sheep by 48% (P less than .05). Conversely, subcutaneous fat thickness increased significantly in the control sheep (88%) during this period, but was unchanged in the clenbuterol-fed animals. Warner-Bratzler shear force values of cooked longissimus samples from clenbuterol-fed sheep were significantly greater than shear force values in cooked samples from control lambs; this was not correlated with the extractable neutral lipid content of the muscle. Simple linear regression between ultrasound and carcass measurements of longissimus muscle cross-sectional area and subcutaneous fat thickness yielded correlation coefficients of .80 and .64, respectively. A significantly greater amount of net glycogen synthesis from [U-14C]glucose was observed in longissimus muscle strips from clenbuterol-fed animals than in muscle strips from control sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

Shelf-Life Extension of Vacuum Packaged Frankfurters Made from Beef Inoculated with Streptococcus lactis.

Fresh beef, containing .5% dextrose, was inoculated with Streptococcus lactis , incubated for 3, 5 and 7 d at 7±1°C, and then used to manufacture frankfurters. The frankfurters were vacuum-packaged and stored for 1, 2, 4 and 6 weeks at 3±1°C. Microbial quality was evaluated by examining frankfurters for aerobic and psychrotrophic counts at the end of each storage period. The level of nisin, an antibiotic substance produced by this strain of S. lactis , was also monitored in fresh meat and processed products. During the incubation period, no appreciable reduction in pH occurred in fresh meat. Growth of psychrotrophs was slower in treated than untreated fresh meat, but whether this was due to presence of nisin or competition resulting from the heavy inoculation with S. lactis is unclear. Before and after processing, nisin levels in the 5- and 7-d incubation-treated groups were higher than in the 3-d group, and all treated groups had higher nisin levels than untreated groups. Little difference in aerobic and psychrotrophic growth was noted with storage time between treated and untreated groups for the 3-d incubation period, but well defined differences were noted in the 5- and 7-d incubation groups, with aerobic growth in treated groups being significantly slowed through the 6-week storage period, and psychrotrophs being 1 to 1.5 log cycles lower at the 6-week evaluation. The growth patterns suggest that nisin played a role in the reduced growth rate of bacteria in treated groups.

Toxicologic studies with lambs fed sugar beets grown on municipal sludge-amended soil: lowered relative hemoglobin in red blood cells and mutagens in blood and excreta.

Sugar beets grown on municipal sludge-amended soil were fed to growing lambs for 66 days. The relative hemoglobin content was significantly lower (P less than 0.05) in the lambs fed the sludge-grown sugar beets. The concentration of direct-acting mutagens was significantly higher (P less than 0.05) than controls in blood and urine of the lambs fed the sludge-grown beets. Cadmium concentration was higher, but not significantly (P greater than 0.05) in the livers and kidneys of the lambs fed the sludge-grown beets as compared with controls. Significant differences between treatment groups were not observed in active or passive K+ influxes in RBC; in the activity of hepatic microsomal aniline hydroxylase in p-nitroanisole-O-demethylase, aminopyrene-N-demethylase, or arylhydrocarbon hydroxylase; in tissue ultrastructure of kidney, liver, or muscle as examined by electron microscopy; or in carcass weight, dressing percentage, quality, or yield grade.

Toxicologic studies with male sheep grazing on municipal sludge-amended soil.

Growing sheep were grazed for 152 d on grass-legume forage growing on soil that had been amended with municipal sewage sludge from Syracuse, N.Y., at 224 metric tons per hectare. Cadmium was higher, but not significantly (p greater than 0.05), in tissues of sheep fed the sludge-grown forage as compared to controls. No significant differences between the sludge or control treatments were found in weight of the complete or cauda epididymis or in percent progressive motility of cauda epididymal sperm. The sludge-treatment group had significantly larger testes (p less than 0.025) when expressed as a percentage of body weight, and higher blood uric acid values (p less than 0.05). There were no observable changes in tissue ultrastructure of liver, kidney, muscle, or testes as examined by electron microscopy in either of the treatment groups. There were no significant differences for rate of animal weight gain, carcass weight, dressing percentage, or quality or yield grade of the carcases between the treatment groups.

Toxicologic studies in growing sheep fed silage corn cultured on municipal sludge-amended acid subsoil.

Field corn was grown on subsoil, pH 5.5, that had been amended with 100 dry tons per acre (224 metric tons per hectare) of municipal sewage sludge from Syracuse, New York. The corn plants containing 3.88 ppm dry weight of cadmium were field-chopped and ensiled, and the silage was fed to growing sheep for 225 d. The sheep fed the sludge-grown corn silage showed a significantly (10 higher feed efficiency, (2) higher hepatic microsomal p-nitroanisole O-demethylase activity, and (3) higher concentrations of cadmium in liver and kidney and nickel in kidney as compared to the control animals. No significant treatment effects were observed in mutagenic responses for animal feed or feces samples. No consistent treatment effects were noted during histopathologic examination of sheep tissues.

Cement kiln dusts as a selenium source in sheep rations.

Cement dust has been found to be a source of selenium when included in the rations of sheep. In the work reported, rations including 3% by weight of cement dusts were fed to sheep for 165 days. The dust were taken from 3 collectors located at progressively greater distances from the coal-fired end of the kiln. Selenium levels and blood and tissues of the animals fed the cement dusts increased significantly above those of the control sheep. No tissue abnormalities were observed in animals receiving any of the treatment rations. The source of selenium is believed to derive from its content of fly ash as a result of the coal combustion during cement manufacture.