Nutrient profiles in retail cuts of bison meat.

The objectives were to determine the nutrient composition and variation in eight cuts of bison meat in bulls and heifers and identify nutrient relationships in the clod and sirloin by principal component analysis. The nutrients analyzed were: energy, protein, total fat, saturated fat, monounsaturated fat, polyunsaturated fat, transfat, cholesterol, vitamin A, Ca, Fe, Na and moisture. Differences were observed in fat components between cuts and bulls had higher (P<0.05) amounts of total, saturated, monounsaturated and polyunsaturated fat in the blade compared to the other cuts. The sirloins had less (P<0.05) cholesterol than all the other cuts in bulls and the clod in heifers. Fat varied more than protein and moisture in all cuts. Four principal components (PC) accounted for 63.9% of the total variation of the nutrient composition. Total, monounsaturated and saturated fats were in PC1 and cholesterol in PC2 showing that cholesterol is independent of other fats. If dietary alterations elicit changes in bison meat fatty acid profiles, it may be possible to reduce cholesterol independent of total, monounsaturated or saturated fat.

Influence of steam-peeled potato-processing waste inclusion level in beef finishing diets: effects on digestion, feedlot performance, and meat quality.

Inclusion of potato-processing waste (PW) from the frozen potato products industry in high-grain beef cattle finishing diets was evaluated in two studies. In a randomized complete block design, 125 crossbred yearling heifers (365 +/- 0.3 kg initial BW; five pens per treatment; five heifers per pen) were used to evaluate PW level on feedlot performance and meat quality. Heifers were fed for 85 (two blocks) or 104 d (three blocks). In a digestion study, four ruminally, duodenally, and ileally cannulated Holstein steers (474.7 +/- 26.6 kg initial BW) were used in a 4 x 4 Latin square design to evaluate effects of PW level on ruminal fermentation, site of digestion, and microbial protein synthesis. The control diet for both studies contained 80% corn, 10% alfalfa hay, 5% concentrated separator by-product (CSB), and 5% supplement (DM basis). Potato waste replaced corn and separator by-product (DM basis) in the diet at 0, 10, 20, 30, and 40% in the feedlot study, and at 0, 13, 27, and 40% in the digestion study. In the feedlot study, DMI decreased (linear; P = 0.007) with increasing inclusion of PW. Increasing PW decreased ADG and feed efficiency from 0 to 30% and then increased at 40% (quadratic; P < 0.01). Calculated dietary NEg concentrations did not differ among treatments (P = 0.18). Hot carcass weight decreased as PW increased from 0 to 30% and then increased at 40% PW (cubic; P < 0.01). Fat thickness and longissimus muscle area decreased with increasing PW (linear; P < 0.05). Level of PW did not affect marbling or liver scores (P > 0.30). No difference (P > 0.20) was observed for Warner-Bratzler shear force at 0, 10, 20, and 30% PW levels; however, 40% PW resulted in lower (P = 0.05) shear force values. Taste panel scores for juiciness and flavor intensity did not differ with increasing PW (P > 0.30). Steaks from cattle fed 0% were scored less tender than 10 and 40% PW (cubic; P < 0.05). In the digestion study, DMI decreased (quadratic; P < 0.01) with increasing PW. Ruminal pH and total VFA concentration increased (linear; P < 0.05) and true N disappearance from the stomach complex and apparent total-tract N disappearance decreased with increasing level of PW (linear; P < 0.01). Starch intake and ruminal disappearance decreased with increasing level of PW (quadratic; P < 0.05). Inclusion of PW decreased feedlot performance, with little effect on carcass characteristics or meat quality. Optimal inclusion of PW in finishing diets may depend on the cost of transportation and other dietary ingredients.

Validation of dual x-ray absorptiometry for body-composition assessment of rats exposed to dietary stressors.

Evidence of the validity and accuracy of dual x-ray absorptiometry (DXA) to measure soft-tissue composition of laboratory rats with altered body composition associated with nutritional perturbations is lacking. We compared DXA determinations made in prone and supine positions with measurements of chemical composition of 49 male, weanling Sprague-Dawley rats that were fed the basal AIN-93 growth diet, were fed the basal diet modified to contain 30% fat, were fasted for 2 d, were limit fed 6 g of the basal diet daily for 1 wk, or were treated with furosemide (10 mg/kg intraperitoneally 2 h before DXA). DXA produced similar estimates of body mass and soft-tissue composition in the prone and supine positions. DXA estimates of body composition were significantly correlated with reference composition values (R(2) = 0.371-0.999). DXA discriminated treatment effects on body mass, fat-free and bone-free mass, fat mass, and body fatness; it significantly underestimated body mass (1% to 2%) and fat-free and bone-free mass (3%) and significantly overestimated fat mass and body fatness (3% to 25%). The greatest errors occurred in treatment groups in which body mass was diminished and body hydration was decreased. These findings suggest that DXA can determine small changes in fat-free, bone-free mass in response to obesity and weight loss. Errors in DXA determination of fat mass and body fatness associated with extra corporeal fluid and dehydration indicate the need for revision of calculation algorithms for soft-tissue determination.

Areas with high concentrations of selenium in the soil and forage produce beef with enhanced concentrations of selenium.

Beef provides a significant portion of human dietary selenium (Se), and it is possible that modest portions of beef produced in areas with high-Se soil and forage could provide the entire Recommended Dietary Allowance (RDA) for Se. The present study has addressed the environmental conditions that resulted in the production of high-Se beef. One hundred and thirty-eight cull cows were obtained from 21 ranches in five distinct geographic regions that, on the basis of soil parent material, reports of Se deficiency, and previous soil and forage Se surveys, were likely to have high or low Se concentrations in the soil. Grass and soil samples were taken from ranch sites, and hair, whole blood, skeletal muscle, diaphragm muscle, and liver samples were obtained from the animals. Hair and whole blood samples were taken 1 day prior to shipping. Selenium concentrations of all samples were determined by hydride generation atomic absorption spectroscopy. Geographic origin affected Se content of all samples (p < 0.05). Selenium concentrations in soil (r = 0.53; p < 0.01) and grass (r = 0.63; p < 0.01) were correlated to Se content of skeletal muscle. Selenium concentrations in whole blood, diaphragm, hair, and liver also were significantly correlated to Se content of skeletal muscle (p < 0.01). Cows that received Se in mineral supplements did not have significantly higher concentrations of Se in sampled tissues (p > 0.05). Results of this study suggest that the greatest source of variation in Se content of bovine skeletal muscle was the geographic region from which the beef originated and not production or management practices. Results also demonstrated that a 100 g serving of high-Se beef could provide 100% of the RDA for Se.

Increased body fat in streptozotocin diabetic rats treated with intensive subcutaneous insulin therapy vs. islet transplantation.

The continued development of novel insulin treatment is predicated on the hypothesis that strict glycemic control is necessary to prevent the secondary complications of diabetes. Although dramatically successful in reducing selected secondary complications, intensive insulin therapy has consequences. These include hypoglycemia, weight gain, and body fat accumulation. In the present studies we compared a model of intensive insulin therapy in diabetic rats and contrasted weight gain and body fat accumulation with pancreatic islet transplantation. Female Wistar Furth rats (173 g) administered streptozotocin (55 mg x kg(-1), iv) remained diabetic (DB) for four or nine weeks. At week three, a third group was transplanted (TRAN) with islets of Langerhans (3519 +/- 838 150 microm islets); one week later group four began intensive subcutaneous insulin therapy (ISIT; 4 x 0.5-1.0 U regular insulin x day(-1)). Within one week ISIT rats had normalized plasma glucose; levels were not different from age matched controls (CN) or TRAN animals (ISIT 10.6 +/- 1.7, CN 7.2 +/- 0.4, TRAN 7.7 +/- 0.8 mmol x L(-1), P > 0.05). The cumulative occurrence of one episode of hypoglycemia (< 2.8 mmol x L(-1)) occurred in 50% of ISIT rats. At study termination, body weight of ISIT and CN rats did not differ (199 +/- 4 vs. 207 +/- 3, P > 0.05). While carcass protein content was similar for TRAN, ISIT, and CN animals, the body fat of ISIT animals was 24% greater than in CN rats and 21% greater than in TRAN rats (P < 0.05). Correlation of body fat vs. plasma glucose illustrated hypoglycemia contributed to the body fat gain of ISIT rats (n = 8, r = -0.70, P = 0.0535). These studies illustrate a disproportionate gain of body fat from ISIT, an effect not observed with islet transplantation. Thus, the metabolic benefit ascribed to islet transplantation appears related to the absence of hypoglycemia.

Riboflavin and niacin concentrations of bison cuts.

We analyzed the riboflavin and niacin contents of individual cuts from clod (triceps brachii), ribeye (longissimus thoracis), top round (semimembranosus), and top sirloin (gluteus medius) from 24 fed bison bulls. The bulls came from producers in the United States and Canada and had consumed concentrate diets plus hay free choice for at least 100 d. The mean riboflavin and niacin concentrations of all of the bison cuts combined were .094 and 1.910 mg/100 g wet weight, respectively. The riboflavin and niacin content values did not differ (P < .05) among the cuts of meat. Cuts from individual bulls were significantly different (P < .05) with regard to both riboflavin and niacin contents. Little variation was observed in riboflavin and niacin content of five bison from the same producer and two bison from another producer. These content values may be used in estimating the riboflavin and niacin content of bison meat.

Determination of saleable product in finished cattle and beef carcasses utilizing bioelectrical impedance technology.

Two experiments were performed to develop prediction equations of saleable beef and to validate the prediction equations. In Exp. 1, 50 beef cattle were finished to typical slaughter weights, and multiple linear regression equations were developed to predict kilograms of trimmed boneless, retail product of live cattle, and hot and cold carcasses. A four-terminal bioelectrical impedance analyzer (BIA) was used to measure resistance (Rs) and reactance (Xc) on each animal and processed carcass. The IMPS cuts plus trim were weighed and recorded. Distance between detector terminals (Lg) and carcass temperature (Tp) at time of BIA readings were recorded. Other variables included live weight (BW), hot carcass weight (HCW), cold carcass weight (CCW), and volume (Lg2/Rs). Regression equations for predicting kilograms of saleable product were [11.87 + (.409 x BW) - (.335 x Lg) + (.0518 x volume)] for live (R2 = .80); [-58.83 + (.589 x HCW) - (.846 x Rs) + (1.152 x Xc) + (.142 x Lg) + (2.608 x Tp)] for hot carcass (R2 = .95); and [32.15 + (.633 x CCW) + (.33 x Xc) - (.83 x Lg) + (.677 x volume)] for cold carcass (R2 = .93). In Exp. 2, 27 beef cattle were finished in a manner similar to Exp. 1, and the prediction equations from Exp. 1 were used to predict the saleable product of these animals. The Pearson correlations between actual saleable product and the predictions based on live and cold carcass data were .91 and .95, respectively. The Spearman and Kendall rank correlations were .95 and .83, respectively, for the cold carcass data. These results provide a practical application of bioelectrical impedance for market-based pricing. They complement previous studies that assessed fat-free mass.

Bioelectrical impedance: fat content of beef and pork from different size grinds.

Multiple linear regression equations were developed for predicting the percentage of fat content of beef and pork. The predictor variables were bioelectrical resistance, temperature, and weight of product. Equations were developed for trim and product ground through a .95- or a .32-cm plate. The trim, .95-cm, and .32-cm grinds had 64, 108, and 96 observations, respectively, for beef product and 56, 101, and 92 observations, respectively, for pork product. Each of these observations was the average of bioelectrical impedance measurements taken in triplicate. The fat percentage ranges were 4 to 50% for beef and 7.5 to 50% for pork. The prediction equation applied to beef trim provided the following values: R2 = .80, Mallows's C(P) = 5.1, and root mean square error = 6.64. The R2 for equations predicting fat percentage in .95- and .32-cm ground beef were .84 and .95, respectively. The prediction equation applied to pork trim provided the following values: R2 = .77, Mallow's C(P) = 5.0, and root mean square error = 6.2. The R2 for equations predicting fat percentage in .95- and .32-cm ground pork were .87 and .96, respectively. The analyses were repeated with data sets of observations with less than 35% fat. The sample sizes and R2 for the trim, .95-, and .32-cm ground beef were 48, .36; 76, .60; and 65, .86; respectively. The sample sizes and R2 for the trim, .95-, and .32-cm ground pork were 42, .64; 62, .66; and 58, .92; respectively. Resistance, temperature, and weight remained as predictor variables for ground product with less than 35% fat. The smaller the grind, the more accurate the prediction. These results are positive for developing inexpensive, on-line systems for efficiently mixing ground product to a specific fat percentage.

Soft tissue composition of pigs measured with dual x-ray absorptiometry: comparison with chemical analyses and effects of carcass thicknesses.

Evidence of the validity and accuracy of dual x-ray absorptiometry (DXA) to measure in vivo body composition is limited. We compared DXA estimates made in prone and side positions with measurements of chemical composition of 20 pigs (10 barrows and 10 gilts) weighing 52-113 kg. DXA yielded similar estimates of body composition in prone and side positions. DXA estimates of body composition were significantly correlated with reference compositional values (r2 = 0.927-0.998). No significant differences were found for determinations of body weight, fat mass (FM), fat free mass (FFM), bone-free, and fat-free mass (BFFFM) between DXA and chemical determinations. DXA significantly underpredicted percent fat (% fat); it underestimated FM (20%, P > 0.05), and overestimated FFM and BFFFM (6 and 9%, respectively, P > 0.05). Differences between individual determinations of FM and % fat by chemical analyses and DXA were significantly correlated with mean values. No significant correlations were found between the differences for weight, FM, % fat, FFM and BFFFM and measurements of carcass breadth (19-28 cm) and width (15-25 cm). Total errors in determination of DXA body composition variables were similar with body thicknesses less than and greater than 24 cm. These findings indicate that DXA is a valid and accurate method for determination of soft tissue composition. Initial problems with DXA determinations of % fat apparently have been reconciled partially with revisions in soft tissue analytic software.

Prediction of fat-free mass of pigs from 50 to 130 kilograms live weight.

Seventy-two Duroc x Hampshire x Yorkshire pigs were used to evaluate bioelectrical impedance procedures to predict fat-free mass of live pigs. Pigs were allotted by sex, ancestry, and weight. Pigs (12 gilts and 12 barrows) averaging 50+/-2.4 kg were slaughtered to establish a baseline for body composition. A pen of six gilts and a pen of six barrows were randomly selected for slaughter when the pen averaged either 70, 90, 110, or 130 kg. Pigs were weighed, then a four-terminal plethysmograph was used to measure resistance (omega) and reactance (omega), and length (cm) was measured between detector terminals. Pigs were slaughtered 12 h later, and carcasses were chilled for 24 h. The right side was ground twice and mixed and samples were frozen for later analyses of fat content. Actual fat-free mass (ActFFM) was determined from the weights and percentage of fat. Predicted fat-free mass (PredFFM) was calculated using the following equation: Pred FFM = .486 (live weight) - .881 (resistance) + .48 (length) + .86 (reactance) + 7.959. The correlation coefficients between ActFFM and PredFFM ranged from .66 to .91 overall. Correlation coefficients approximating slaughter weight (90 kg) were .94 (P < .02). Fat-free mass was underestimated by the prediction equation at all slaughter weights, but the predicted fat-free mass was highly correlated to the actual fat-free mass, except for the 110-kg gilts (r = .68, P = .15) and the 130-kg barrows (r = .65, P = .16). The data support the use of bioelectrical impedance to measure fat-free mass over a wide range of weights for finishing pigs.

Concentrations of selected vitamins and selenium in bison cuts.

We analyzed individual cuts from clod (Triceps brachii), ribeye (Longissimus thoracis), top round (semimembranosus), and top sirloin (Gluteus medius) from 12 fed bison bulls for content of selected vitamins and selenium. The bulls came from producers in the United States and Canada and had consumed concentrate diets plus hay free choice for at least 180 d. The mean nutrient concentrations of all of the bison cuts combined were as follows (per 100 grams of wet weight): .045 mg thiamin, .253 mg vitamin B6, 2.131 microg vitamin B12, no detectable vitamin C, .848 microg vitamin A, .047 mg alpha-tocopherol, .013 mg tau-tocopherol, and 25.464 microg selenium. The nutrient content values did not differ (P > .05) among the cuts of meat. Cuts from individual bulls were different (P < .05) with regard to alpha- and tau-tocopherols, selenium, and vitamin A but not with regard to thiamin, vitamin B6, and vitamin B12. Nutrient concentrations, with the exception of one nutrient, of five bison from the same producer were similar. Great variation was observed between the alpha- and tau-tocopherols, selenium, and vitamin A contents among bison bulls but not among cuts of meat.

Fatty acid composition of commercially manufactured omega-3 enriched pork products, haddock, and mackerel.

This study was conducted to determine the commercial feasibility of feeding a 15% ground flaxseed diet to finishing hogs for up to 42 d before slaughter and to compare the fatty acid composition of the resulting pork products with commercially produced haddock and mackerel. Eighty-seven pigs were fed a control diet (predominantly corn, soybean meal-based) and then a similar diet containing 15% flaxseed for the last 28 (FS28) or 42 d (FS42) before slaughter. Control pigs were continued on the control diet (CO28 and CO42). Percentages of saturated and monounsaturated fatty acids were decreased (P < .0001), and percentages of polyunsaturated fatty acids, most prominently alpha-linolenic acid [18:3(n-3)] and the sum of all (sigma) measured (n-3) fatty acids, were increased (P < .0001) in all pork tissues (backfat, liver, and longissimus thoracis) and products (lard, muffins, Braunschweiger, and bacon) due to dietary flaxseed. The percentage of arachidonic acid [20:4(n-6)] decreased in FS28 compared to CO28 liver (P < .0001) and in longissimus thoracis polar fraction FS42 compared to CO42. The percentage of 18:3(n-3) was similar in mackerel, CO bacon, and CO longissimus thoracis, and the percentage of 18:3(n-3) and sigma(n-3) in haddock was similar to that in FS bacon and FS longissimus thoracis. The percentage of 20:5 in FS42 longissimus thoracis, polar fraction, approached the level in haddock, but the percentages of 20:5 and 22:6 were greater (P < .0001) in mackerel than in haddock. The percentage of sigma(n-3) was greater (P < .0001) in mackerel than in haddock and sigma(n-6) was greater (P < .0001) in haddock than in mackerel. Commercial production of omega-3 enriched pork products can provide consumers a feasible alternative to a diet higher in fish than that normally consumed.

Pancreatic islet transplantation improves body composition, decreases energy intake and normalizes energy efficiency in previously diabetic female rats.

We investigated the weight gain, body composition, and feed efficiency of female Wistar Furth rats (170 +/- 1 g) made diabetic with streptozotocin (55 mg/kg intravenously), then infused intraportally with 3519 +/- 838 (150 mu equivalent units) syngeneic pancreatic islets of Langerhans. After islet transplants (5-6 wk), nutritional energetics were evaluated in transplanted rats (Transplant), and also in 3- and 9-wk diabetic (Diab-3, 9) and control rats treated with sham infusions and similar surgical manipulations (Sham-3, 9). Diabetic rats demonstrated marked hyperphagia, which was corrected by islet transplantation (577 +/- 53 vs. 266 +/- 19 kJ/d; P < 0.0001) and was not different than sham control rats (285 +/- 24 kJ/d; P > 0.05). Three weeks of diabetes resulted in a lower protein (Diab-3, 24.8 +/- 2.6 g vs. Sham-3, 30.9 +/- 1.0 g) and fat content (1.9 +/- 0.8 g vs. 11.6 +/- 1.7 g) in the rats' carcasses. However, 6 wk after islet transplantation, rats receiving islets (Transplant) were not different than control rats (Sham-9) (31.9 +/- 1.7 g vs. 33.3 +/- 1.9 g protein and 15.4 +/- 3.0 g vs. 15.1 +/- 3.2 g fat). Three weeks of diabetes resulted in a lesser energy efficiency compared with Sham rats (2.7 +/- 2.0 vs. 7.1 +/- 1.9 kJ gained/100 kJ ingested); islet-transplanted rats were not different than Sham-9 rats (4.9 +/- 2.3 vs. 4.7 +/- 1.4 kJ gained/100 kJ ingested). These data illustrate that islet transplantation in previously diabetic female rats improves growth with proportional gains in body protein and fat mass. This is modulated in part by a reduced food intake and an energy efficiency that is improved relative to controls. These studies offer an optimistic outlook for the continued development of more physiological insulin delivery strategies that preclude the nutritional complications associated with exogenous insulin administration.

Islet transplantation reverses carcass protein loss in diabetic rats without inducing disproportionate fat accumulation.

The Diabetes Control and Complications Trial demonstrated that intensive insulin therapy (IIT) improves many secondary complications of insulin-dependent diabetes mellitus. However, weight gain in IIT is associated with increased body fat, and no improvement in lean body mass. In the present study we investigated the effects of experimental diabetes on changes in body composition and probed the benefit of glycaemic control achieved through islet transplantation. Male Wistar Furth rats (weight 273 +/- 9 g) made diabetic for 2 weeks with streptozotocin (55 mg/kg) were infused intraportally with 3265 +/- 692 (150 microns islet equivalent units) syngeneic islets of Langerhans. Body composition was evaluated by proximate analysis in carcasses of transplant rats (Trans), and also in rats made diabetic for 2 or 7 weeks (Db-2, Db-7) and in 2- and 7-week sham controls (Sham-2, Sham-7). Fed plasma glucose levels were 7.3 +/- 1.1, 28.2 +/- 2.4, 26.8 +/- 3.9, 7.5 +/- 1.0 and 7.0 +/- 0.1 mm/l, respectively, and neither glucose tolerance nor fasting plasma insulin differed between control vs transplant rats (p > 0.05). Two weeks of diabetes resulted in a body weight 82% of that of controls (240 +/- 5 vs 292 +/- 8 g, p < 0.05) and 5 subsequent weeks of diabetes further suppressed growth by an additional 12% (p < 0.05). Five weeks following islet transplantation, islet-transplant rats had regained lost weight and were not significantly different from control animals (274 +/- 19 vs 291 +/- 21 g, p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Bioelectrical impedance can predict skeletal muscle and fat-free skeletal muscle of beef cows and their carcasses.

Multiple linear regression equations predicting total skeletal muscle (TM) and total skeletal fat-free muscle (TFFM) weight were developed from data of 33 beef cows. Animals varied in weight (385 to 749 kg), age (3 to 10 yr), and fatness (.13 to 2.54 cm). A four-terminal impedance meter/plethysmograph measured resistance and reactance on the live animals, exsanguinated (bled) animals, and on the subsequent hot and cold carcasses. Stainless steel, sterile needles (20-gauge) were used as electrodes. They were inserted to depths of 12.7 mm for measurements made before and after exsanguination and to 25.4 mm for carcass measurements. Cold carcass resistance and reactance were measured a second time using 13-gauge needles inserted to depth of 76.2 mm. Distance between detector electrodes was measured. Carcass sides were physically separated into muscle, fat, and bone. Chemical composition (moisture, protein, and fat) was determined on the muscle portion. Equations predicting TM weight from live, bled, hot carcass, and cold carcass data had adjusted R2 values of .90, .96, .94, and .92, respectively. Analogous adjusted R2 values for TFFM weight were .87, .93, .90, and .87. Resistance was a predictor variable in all equations. The use of larger needles resulted in higher adjusted R2 values and inclusion of reactance as a predictor variable. Mallows Cp values were close to the ideal value of the number of independent variables in the prediction equations plus one (1).(ABSTRACT TRUNCATED AT 250 WORDS)

Bioelectrical impedance can predict skeletal muscle and fat-free skeletal muscle of beef cow primal cuts.

Multiple linear regression equations predicting total skeletal muscle (TM) and total skeletal fat-free muscle (TFFM) of chuck, rib, loin, and round were developed from data of 33 beef cows. Primal cuts were obtained in accordance with NAMP specifications. A four-terminal impedance meter/plethysmograph measured resistance and reactance on each cut using 20- and 13-gauge needles as electrodes. Weight, internal temperature, and distance between detector electrodes were recorded. Each cut was physically separated into muscle, fat, and bone. Chemical composition (moisture, protein, and fat) was obtained on the muscle portion of each cut so that TFFM could be obtained by multiplying TM x 1 minus the percentage of fat from the proximate analysis. The predictor variables for all combinations of cuts and electrode sizes were weight, distance between detector electrodes, temperature, and resistance, except for the round for which reactance was a fifth predictor. The P value for the resistance coefficient was < .001 for all 16 prediction equations. Adjusted R2 values of the prediction equations ranged from an average of .91 for the rib to an average of .96 for the round. Mallows Cp values were close to the ideal value of the number of independent variables in the prediction equations plus one (1). Prediction equations for the different size electrodes were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting total weight of retail-ready lamb cuts from bioelectrical impedance measurements taken at the processing plant.

Data of sixty finished, crossbred lambs were used to develop prediction equations of total weight of retail-ready cuts (SUM). These cuts were the leg, sirloin, loin, rack, shoulder, neck, riblets, shank, and lean trim (85/15). Measurements were taken on live lambs and on both hot and cold carcasses. A four-terminal bioelectrical impedance analyzer (BIA) was used to measure resistance (Rs, ohms) and reactance (Xc, ohms). Distances between detector terminals (L, centimeters) were recorded. Carcass temperatures (T, degrees C) at time of BIA readings were also recorded. The equation predicting SUM from cold carcass measurements (n = 53, R2 = .97) was .093 + .621 x weight-.0219 x Rs + .0248 x Xc + .182 x L-.338 x T. Resistance accounted for variability in SUM over and above weight and L (P = .0016). The above equation was used to rank cold carcasses in descending order of predicted SUM. An analogous ranking was obtained from a prediction equation that used weight only (R2 = .88). These rankings were divided into five categories: top 25%, middle 50%, bottom 25%, top 50%, and bottom 50%. Within-category differences in average fat cover, yield grade, and SUM as a percentage of cold carcass weight of carcasses not placed in the same category by both prediction equations were quantified with independent t-tests. These differences were statistically significant for all categories except middle 50%. This shows that BIA located those lambs that could more efficiently contribute to SUM because a higher portion of their weight was lean.

Bioelectrical impedance analysis for the prediction of fat-free mass in lambs and lamb carcasses.

Ninety-eight commercial crossbred lambs, average weight 55.1 kg (+/- 4.95), were used to evaluate bioelectrical impedance analysis (BIA) as a prediction method for fat-free tissue from live lambs and lamb carcasses. Lambs were transported to the abattoir, restricted from feed for 10 h, weighed (LWt), and measured for body resistance (Rs, ohms), body reactance (Xc, ohms), and distance between detector terminals (L, cm). Following slaughter, hot carcasses were weighed (HCWt; average 31.4 +/- 2.8 kg) and impedance measurements of Rs, Xc, and L were recorded from readings on the dorsal and lateral sides of the carcasses. Temperatures (average = 39.2 degrees C) were recorded. Carcasses were chilled for 24 h. Cold carcass weights (CWt; average 31.1 +/- 2.8 kg) and temperatures (average = 1.0 degrees C) were recorded and BIA measurements were repeated. Carcasses were split down the midline and right sides were ground three times and sampled for chemical analysis of fat, moisture, ash, and protein. Fat-free mass (FFM) was calculated as [Wt-(Wt x %Fat)]. Fat-free soft tissue (FFST) was calculated as the sum of carcass chemical protein and carcass water. Regression equations predicting fat-free tissue for the live lambs (FFMlive and FFSTlive), hot carcasses (FFMhot and FFSThot), and cold carcasses (FFMcold and FFSTcold) were developed. The independent variables LWt, Rs, and Xc accounted for 77.7% (residual mean square error [RMSE] = 1.97 kg) of the variation in FFMlive and 78.6% (RMSE = 1.78 kg) of the variability of FFSTlive.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of bioelectrical impedance to predict leanness of Boston butts.

The objective of this research was to make available bioelectrical impedance technology for the prediction of kilograms of lean and kilograms of fat-free muscle of Boston butts. Seventy butts were removed from 70 pork carcasses according to standard procedures (NAMP, #406), with the exception that the fat was not removed. After the weight in kilograms (BUTT) and internal temperature in degrees centigrade (TEMP) were recorded, each butt was measured for resistance (Rs, ohms), reactance (Xc, ohms), and distance (L, centimeters) between detector terminals four different ways: parallel or perpendicular to the top of the carcass and on either lean surface or fat surface of the cut. Each cut was physically separated into lean, fat, and bone. Chemical composition (moisture, protein, and fat) was determined on the lean portion. Variable selection analysis was used to develop equations for predicting kilograms of lean and kilograms of fat-free muscle of Boston butts. Results of measurements of the four sites were quite similar; however, measuring perpendicularly on the lean surface is recommended. The prediction equation for kilograms of lean from measurements thus taken is as follows: .461-.0304 x TEMP + .576 x BUTT - .0118 x Rs + .00845 x Xc + .0630 x L. The respective coefficients of these independent variables for predicting kilograms of fat-free muscle are .537, -.0415, .479, -.0139, .00804, and .0764. In an industry application of these coefficients, recording temperature would not be imperative because the temperature range would be sufficiently narrow to render temperature of little practical influence when separating butts according to leanness.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired thyroid hormone status and thermoregulation during cold exposure of zinc-deficient rats.

Forty-five male, weanling Sprague-Dawley rats were matched by weight into three groups (n = 15). One group was fed ad libitum a semipurified diet containing all essential nutrients and 30 ppm of zinc (control). A second group was fed ad libitum a similar diet but with a deficient zinc intake of less than 1 ppm (ZnD). A third group was pair-fed (PF) the control diet in amounts equal to that consumed by the matched ZnD animals. After 42 days, the animals were fasted for 12 hr then five animals from each group were sacrificed and the remainder was exposed to 3 degrees C for 6 hr. Rectal temperatures were lower (p less than 0.05) in ZnD at 23 degrees C and during cold exposure. Plasma thyroxine (T4) and triiodothyronine (T3) concentrations were reduced (p less than 0.05) at room temperature in ZnD rats. During cold exposure, the ZnD animals had depressed (p less than 0.05) plasma thyrotropin, T4 and T3 concentrations. Thus, ZnD adversely affects thermoregulatory performance of rats acutely exposed to cold by influencing thyroid hormone metabolism.