Carcass Tissue Research Articles

Carcass size, not source or taxon, dictates breeding performance and carcass use in a burying beetle.

Small vertebrate carcasses represent critical resources for many terrestrial organisms, including burying beetles, which rely on carcasses for survival and breeding. Carcass attributes can influence the reproduction of burying beetles, yet most studies on their breeding ecology have used laboratory-reared carcasses of limited sizes. We conducted breeding and feeding experiments using a wide size range of lab (laboratory mice) and wild carcasses (wild mammals, birds and reptiles) to investigate how carcass size, source and taxon affect various breeding outcomes (e.g. clutch size, brood size and brood mass) of the burying beetle Nicrophorus nepalensis. Our results reveal a hump-shaped relationship between carcass size and breeding performance, with optimal breeding outcomes occurring on medium-sized carcasses. Furthermore, despite the variation in carcass tissue nutritional composition, breeding outcomes and larval growth did not differ between the two carcass sources or among the three wild carcass taxa. Finally, we found a larval quality-quantity trade-off across the range of carcasses examined, with carcass size shaping the larval life-history traits. Overall, these results elucidate how carcass resources may influence the breeding performance of burying beetles. Importantly, our study provides solid evidence validating decades of research using lab carcasses to study the reproductive ecology of burying beetles.

Survival of Calliphora vicina (Diptera: Calliphoridae) embryos under cold temperature conditions: forensic implications.

Most blow flies (Diptera: Calliphoridae) species are sarcosaprophagous during the larval stage, primarily feeding on the soft tissues of carcasses during the early stages of decomposition, making them valuable forensic indicators for minimum post-mortem interval (minPMI) estimations. Like other insects, their developmental rates are strongly influenced by the environmental temperature. Although several studies have examined the influence of temperature on the development of different blow fly species, the impact of cold temperatures remains largely unstudied, despite its potential forensic implications. The present study investigates the effect of three cold temperatures (0, -2.5 and -5°C) on the survival of Calliphora vicina embryos of five different ages (0%, 20%, 40%, 60% and 80% of the total embryonic development) and two exposure times (6 and 24 h). Our results revealed significant differences in egg survival at the earliest embryonic stages (0% and 20% of the total embryonic development), resulting in high mortality rates. While at 20% of the total embryonic development high mortality was only observed under -5°C, at 0% of the total embryonic development high mortality rates were observed at all the temperatures tested. Although C. vicina embryos demonstrate tolerance to cold temperatures once they have completed the first 20% of the total embryonic development, potentially mitigating the impact of cold weather events, the possibility of minPMI underestimations due to the death of the first egg batches should not be disregarded. Additionally, considering that the embryonic development stages may last for several days under low temperatures, caution should be taken in the analysis of entomological evidence if a cadaver is discovered following cold weather episodes.

Optimal level of dietary arginine enhances growth performance, haemato-biochemical status, metabolic responses and growth-related gene expression of GIFT juveniles reared in inland saline water

The effects of arginine levels in diets on growth performance, survival, and haemato-biochemical responses and gene expression of genetically improved farmed tilapia (GIFT) juveniles raised in inland saline water (ISW) of 10 ppt were evaluated through a 60-day growth trial. Seven isoproteinaceous (⁓320 g protein/kg), isolipidic (80 g/kg) and isoenergetic (16.8 MJ DE/kg) diets with graded levels of arginine viz. A10 (10 g/kg), A12.5 (12.5 g/kg), A15 (15.0 g/kg), A17.5 (17.5 g/kg), A20 (20.0 g/kg), A22.5 (22.5 g/kg) and A25 (25.0 g/kg) were prepared. Acclimated GIFT juveniles (3.75 ± 0.017 g) were randomly assigned into seven treatments in triplicate with 15 fish/replicate and fed with respective diets thrice a day on a satiation basis. The percent weight gain, specific growth rate, protein efficiency ratio, whole carcass protein, tissue alanine and aspartic acid aminotransferase activities, serum total protein, albumin and globulin concentration and expression of IGF-1 & IGF-1R genes of fish significantly increased, while feed conversion ratio significantly decreased with increasing arginine in the diet up to 17.5 g/kg and decreased thereafter. Additionally, white blood cell count increased with rising arginine levels in the diet. However, body indices, survival, whole carcass lipid, total ash and essential amino acids contents, activities of digestive and antioxidant enzymes, serum glucose level and blood haemoglobin level and red blood cell count of fish remained unchanged for different treatments. Based on broken-line regression and second order polynomial regression models in relation to hepatic IGF-1 gene expression and percent weight gain, the dietary optimal arginine level was found to be 15.97 and 16.76 g/kg and 17.06 and 17.41 g/kg, respectively with the optimum range of 15.97 to 17.41 g/kg for successful culture of GIFT in ISW of 10 ppt salinity.

Using Image Analysis Technique for Predicting Light Lamb Carcass Composition.

Over the years, numerous techniques have been explored to assess the composition and quality of sheep carcasses. This study focuses on the utilization of video image analysis (VIA) to evaluate the composition of light lamb carcasses (4.52 ± 1.34 kg, mean cold carcass weight ± SD). Photographic images capturing the lateral and dorsal sides of fifty-five light lamb carcasses were subjected to analysis. A comprehensive set of measurements was recorded, encompassing dimensions such as lengths, widths, angles, areas, and perimeters, totaling 21 measurements for the lateral view images and 29 for the dorsal view images. K-Folds stepwise multiple regression analyses were employed to construct prediction models for carcass tissue weights (including muscle, subcutaneous fat, intermuscular fat, and bone) and their respective percentages. The most effective prediction equations were established using data from cold carcass weight (CCW) and measurements from both dorsal and lateral views. These models accounted for a substantial portion of the observed variation in the weights of all carcass tissues (with K-fold-R2 ranging from 0.83 to 0.98). In terms of carcass tissue percentages, although the degree of variation explained was slightly lower (with K-fold-R2 ranging from 0.41 to 0.78), the VIA measurements remained integral to the predictive models. These findings underscore the efficacy of VIA as an objective tool for assessing the composition of light lamb carcasses, which are carcasses weighing ≈ 4-8 kg.

Prediction of the carcass tissue composition of “Blackbelly” lambs using in vivo and postmortem measurements

Objective. Predict the tissue carcass composition of “Blackbelly” lambs using in vivo and postmortem measurements. Materials and methods. Twenty lambs with an average age and weight of seven months and 29.07±2.88 kg, respectively, were used. Before slaughter, the subcutaneous fat thickness, depth, width and Longissimus dorsi muscle area were measured with ultrasonography. After slaughter, the cold carcass and tissues: muscle, fat and bone weight, were recorded. In the carcass, the thoracic depth, length, perimeter, length and width of the leg, as well as the compactness index, were also measured and recorded. Correlation analysis and regression models were used to predict tissue carcass composition. Results. The carcass tissues were correlated with L. dorsi muscle depth (p≤0.05; r-values ranged from 0.67 to 0.80) and carcass compactness index (p≤0.05; r ranged from 0.54 to 0.75). The r2 for the prediction equations of the carcass tissue composition ranged from 0.71 to 0.78 for fat (p≤0.001). Conclusions. The use of in vivo and postmortem measurements allowed the prediction of tissue carcass composition of lambs, with moderate to high accuracy (r2 >0.71≤ and ≤0.78).

Carcass and non-carcass component yields of trenbolone acetate + estradiol-17β implanted steers vs. non-implanted steers across serial harvest endpoints

ObjectiveWe investigated incremental growth of carcass and non-carcass components and tissue partitioning of implanted or non-implanted steers. Materials and MethodsSteers (n = 80; 271 ± 45 kg) were paired and randomized to harvest date (d 0, 42, 84, 126, 168, 210, 252, 294, 336, or 378), and individuals within pairs were randomized to CON (negative control) or REV (Revalor-XS, Merck Animal Health, on d 0 and 190) treatments. Non-carcass components were removed, cleaned, and weighed. Growth coefficients were calculated using the allometric equation Y = bXa. Results and DiscussionEmpty body weight (EBW), and hot carcass weight (HCW) were 6% greater (P < 0.01) in REV steers versus CON. No treatment effects (P ≥ 0.12) occurred for fill or dressed carcass yield (DY); however, EBW, HCW, and DY increased (P ≤ 0.01) and percentage fill decreased as an effect of days on feed (DOF). Absolute fill weight did not change across DOF (P = 0.82). Implanted steers had greater (P ≤ 0.05) absolute mass of blood, head, hide, oxtail, liver, spleen, bladder, heart, reticulum, omasum, stomach, small intestine, intestines, gastrointestinal tract (GIT), total splanchnic tissue, and total offal. Implanted steers also had smaller (P ≤ 0.05) absolute mass of thymus glands and kidney-pelvic- heart fat (KPH) than non-implanted steers. Non-carcass components with lowest growth coefficients included small intestine (0.02), large intestine (0.12), and brain and spinal cord (0.13). However, KPH (2.01) accumulated at more than 2 times the rate of the empty body, whereas cod fat (1.42) and GIT fat (1.61) grew notably faster than the empty body. Implication and ApplicationsResults suggest that Revalor-XS increased body and carcass weights and altered many non-carcass components and their growth co- efficients, ultimately playing key biological, nutritional, and financial roles across sectors of the beef industry.

Влияние препаратов на основе надуксусной кислоты на микробиологические показатели пищевой продукции

The article presents the results of studying the effect of disinfectants based on peracetic acid on the microbiological parameters of poultry products. It was found that the revealed properties of the Creodez NUK-15 solution indicate its high efficiency at low concentrations and open up opportunities for wide application at poultry processing enterprises throughout the Customs Union. Moreover, the drug complies with the environmental characteristics of NTD, does not accumulate in the tissues of carcasses and decomposes in a short time without damaging the external environment.

Multivariate modeling to estimate the composition of carcass tissues of Santa Inês sheep

The purpose of this study was to establish a multivariate model using two complementary multivariate statistical techniques: Factor Analysis and Stepwise Multiple Regression, to predict tissue composition through carcass characteristics of Santa Inês sheep. The data was obtained from 82 Santa Inês sheep under confinement. The predictor variables were carcass characteristics related to weight, yield, morphometric measures and meat cuts. The use of latent variables from factor analysis in multiple regression models eliminates the problem of multicollinearity of the explanatory variables, improving the accuracy of interpretation of results by proposing a better fit of the mathematical model. However, the coefficient of determination (R²) values were moderate for muscle proportion and total fat, and low for bone proportion, indicating that more appropriate independent variables should be used to better predict the proportion of tissues in Santa Inês sheep.

Using fat thickness and longissimus thoracis traits real-time ultrasound measurements in Black Belly ewe lambs to predict carcass tissue composition through multiresponse multivariate adaptive regression splines algorithm

The main idea of the current study was to estimate carcass tissue composition using fat thickness and longissimus thoracis (LT) traits real-time ultrasound measurements (USM) in Black Belly ewe lambs through multiresponse multivariate adaptive regression splines (MARS) algorithms. Twenty-four hours before slaughter, subcutaneous (SFT) and kidney-fat thickness (KFT), LT depth (LTD), width (LTA, cm) and area (LTMA) were measured in 60 lambs (BW of 26.40 ± 7.01 kg). Information on carcass and non-carcass components was recorded after slaughter. The total carcass muscle (TCM), total carcass bone (TCB), and total carcass fat (TCF) had a low to high correlation (P < 0.01) with BW, cold carcass weight (CCW), and LTD, SFT, KFT, and LDMA. The CCW (%65.58) and SFT (%16.70) were the most effective variables, whilst LTD (%9.57) and LTMA (%8.15) were the lowest variables for determining TCB, TCM, and TCF. The multiresponse MARS algorithm provides an accurate and efficient means of estimating TCF, TCB, and TCM.

Influence of Horse Age on Carcass Tissue Composition and Horsemeat Quality: Exploring Nutritional and Health Benefits for Gourmets

The aim of this study was to show the influence of the age of horses currently in use in Poland on the tissue composition of carcasses and the quality of horsemeat. To conduct a detailed dissection and analysis of horsemeat quality, 12 half carcasses of foals and young horses, 14 half carcasses of adult horses, and 14 half carcasses of older horses were selected. A highly significant difference was demonstrated between the linear measurements of the carcasses of foals and young horses compared with those of adult animals. A significantly higher dressing percentage was observed in foals compared with older horses (p ≤ 0.05). Compared with the carcasses from older horses, the foal carcasses provided a significantly higher amount of meat in class I (p ≤ 0.05). Meat obtained from foal carcasses, when compared with the raw material from other age groups of animals, was characterized by a higher number of points for individual qualitative characteristics in the sensory evaluation. The physicochemical properties of horsemeat were dependent on the age of the horses. Compared with the oldest horses, foal meat was characterized by the lowest ability to bind and retain water. The significantly highest content of protein and fat was found in the meat of adult horses compared with the meat of foals. The horsemeats consumed today, compared with those from the 1980s and 1990s, are characterized by a much lower degree of fat deposition in the carcasses, and a higher dressing percentage index and carcass meatiness. This may result in a greater popularization of horsemeat, both among processors of this raw material and the consumers themselves. This can be a very important advantage, pointing to new aspects of food quantity and quality, especially for gourmets of this type of product.

Predicting carcass tissue composition in Blackbelly sheep using ultrasound measurements and machine learning methods.

This study aimed to predict Blackbelly sheep carcass tissue composition using ultrasound measurements and machine learning models. The models evaluated were decision trees, random forests, support vector machines, and multi-layer perceptrons and were used to predict the total carcass bone (TCB), total carcass fat (TCF), and total carcass muscle (TCM). The best model for predicting the three parameters, TCB, TCF, and TCM was random forests, with mean squared error (MSE) of 0.31, 0.33, and 0.53; mean absolute error (MAE) of 0.26, 0.29, and 0.53; and the coefficient of determination (R2) of 0.67, 0.69, and 0.76, respectively. The results showed that machine learning methods from in vivo ultrasound measurements can be used as determinants of carcass tissue composition, resulting in reliable results.

Prediction of carcass tissues composition using the neck and shoulder traits in hair lambs with multiresponse multivariate adaptive regression splines

The present study aimed to predict the carcass tissue composition of hair sheep lambs using a multiresponse multivariate adaptive regression splines algorithm. The left half of sixty-six hair lambs were divided into five commercial cuts (neck, shoulder, rib, loin, and leg), each cut was weighed and dissected in total soft tissue (fat and muscle, TSTW) and bone (BOW). The independent variables included variables obtained from neck and shoulder dissection: weights of the neck (NWE) and shoulder (SWE), neck soft STW (NSTW), neck BW (NBOW), shoulder STW (SSTW), and shoulder BW (SBOW). The prediction of hot carcass weight (HCW), cold carcass weight (CCW), carcass soft tissue weight (CSTW), and carcass bone weight (CBWE) had an R2 that ranged from 0.90 to 0.96. It is concluded that some neck traits and all shoulder traits could be used to predict the carcass tissue weights of hair-suckling lambs correctly.

Nutritional Quality of Meat from Barren Merino Ewes in Comparison to Meat from Traditional Lambs.

In Spain, lamb consumption has decreased over the last few years. To increase farmers' income, we studied the nutritional quality of the barren ewes' meat in comparison to traditional lambs' meat with 10 barren ewes, 10 male lambs, and 10 female lambs from the Merino breed. We measured the subcutaneous fat, muscle color, and carcass tissue composition, as well as proximal composition, mineral, tocopherol, retinol, lutein, and cholesterol contents, and the TPA texture profile, fatty acid profile, and lipid oxidation of the meat. There was no effect of the animal type (males, females, and ewes) on the pH, and the differences in the subcutaneous fat color, lipid oxidation, and texture were irrelevant from a practical point of view. The tissue composition in the three groups of animals reflected a high percentage of saleable meat, with no penalty incurred for intensive fattening in any of the groups. The ewes' meat presented a higher percentage of moisture, collagen, ash, calcium, iron, α-tocopherol, and retinol than the lambs' meat. In addition, it had higher content of DHA and CLA and lower values for the ratio n6/n3, which is beneficial for health, although it also contained more fat, saturated fatty acids, and cholesterol than the lambs' meat.

Pacific salmon as vectors of environmental contaminants: An experimental test confirms synoptic surveys in natural streams

Pacific salmon transfer large quantities of material to tributaries during their spawning migrations, including carcass tissue and labile nutrients but also persistent organic pollutants (POPs) and heavy metals. We conducted a Before-After-Control-Intervention experiment by adding salmon carcasses and eggs to a Michigan (USA) stream that had never received inputs from non-native salmon to understand the bioaccumulation and persistence of biotransported contaminants. Our experimental outcomes were compared to previous studies using meta-analysis. Coincident with the introduction of salmon, the PCB and DDE burden of resident trout significantly increased. However, we did not observe changes in total mercury (Hg). Two years after the salmon addition experiment concluded, resident trout POP concentrations had returned to pre-addition levels, with no difference between the treatment and control reaches. Analysis of effect sizes suggested that the contaminant response observed in our experiment is consistent with field survey observations. Our study suggested that the consumption of salmon eggs drove the increase in POP burden of resident trout while Hg bioaccumulation was influenced by watershed sources. Critically, our study suggests that ecosystems are capable of quickly recovering from POP inputs from species migrations if contaminant sources are removed.

Heavy Metals Levels in Soil, Water and Feed and Relation to Slaughtered Camels’ Tissues (Camelus dromedarius) from Five Districts in Saudi Arabia during Spring

Soil, water, and forage contaminated with toxic heavy metals such as Pb, Cd, and Co can affect the meat and liver quality of camels raised in this area which affect human health. This study aimed to determine the concentrations of Pb, Cd and Co in soil, water, feed and young camels' carcass tissues (meat, liver, whole blood, rumen fluid and rumen tissue) from five districts in Saudi Arabia during the spring. All samples were wet-digested and analyzed by ICP-OES for heavy metals. In the liver, a significantly higher (p < 0.05) concentration of Pb and Co was observed in camels reared in the central and southern districts, while Cd was found significantly higher in the western and northern districts. The concentration of Pb, Cd and Co in meat of camels in the northern district was significantly higher (p < 0.05), and the meat of camels in the west had a higher (p < 0.05) concentration of Co. In addition, the Cd and Co concentrations in rumen fluid samples from camels in the eastern district were significantly higher than in the central district. A negative correlation between the concentration of Pb and Cd in rumen fluid and rumen tissue was reported. The accumulation of Cd, Pb, and Co in meat and liver was below the recommended maximum limit. Therefore, the harmful risk of human consumption of camel meat and liver is not possible.

Estimation of body and carcass composition of crossbred growing bulls from 11th rib dissection

Precise methods for measuring livestock body and carcass composition are essential for both animal and meat scientists. The aim of this study was to calibrate the 11th rib cut dissection method for the estimation of crossbred beef-on-dairy bull empty body (EB) and carcass compositions against reference tissue and chemical postmortem measurements. Sixty-six (66) crossbred bulls from Angus, Limousin and Simmental sires (n = 22 each) crossed on Brown Swiss dams were serially slaughtered along growth from 58 to 534 kg BW. The muscle, adipose tissue and bone contents of the left 11th rib were determined by physical dissection. Linear regressions followed by leave-one-out-cross-validation were tested between rib dissection variates (with or without additional ones: BW or carcass weight, carcass grading or postmortem linear measurements) and reference EB or carcass chemical (water, lipids, proteins, minerals and energy) and tissue (muscles, adipose tissues and bones, only for final slaughter group of 514 ± 12 kg BW, n = 30) compositions. When all bulls are considered (serial slaughter group, n = 66), the inclusion of rib dissection variate together with BW or hot carcass weight allowed precise estimations of EB and carcass masses and proportions of water [R2 ≥ 0.91, residual CV (rCV) ≤ 3.1%], lipid (R2 ≥ 0.88, rCV ≤ 14.0%), protein (R2 ≥ 0.23, rCV ≤ 3.7%) and energy (R2 ≥ 0.89, rCV ≤ 7.7%). Slight further improvements in precision were achieved when carcass grading conformation or fat scores was added to the multiple estimative regressions. Crossbreed effect was significant on the intercept of most of the predictive equations. Especially ×Angus had higher intercepts for lipids, energy and adipose tissues and lower ones for water, proteins and muscles, when compared to ×Limousin and ×Simmental. Further developments using for example rib imaging analysis rather than physical dissection may contribute to large scale and high-throughput phenotyping of body and carcass compositions.

Short-term consumption of the mycotoxin zearalenone by pubertal gilts causes persistent changes in the histoarchitecture of reproductive tissues.

Consumption of zearalenone (ZEN) detrimentally affects tissues and systems throughout the body, and these deleterious effects are especially pronounced in swine. The objectives of this project were to determine the effects of short-term consumption of ZEN (at concentrations that could be found on-farm) on growth, carcass weight, liver weight, and reproductive tissues of pubertal gilts, and to determine if the effects are transient or persistent. Cross-bred gilts (107.25 ± 2.69 kg) were randomly assigned to one of three feed treatments: 1) solvent only for 21 d (CON; n = 10), 2) ZEN for 7 d followed by 14 d of solvent (ZEN-7; 6 mg/d; n = 10), and 3) ZEN for 21 d (ZEN-21; 6 mg/d; n = 10). Body weights were collected at the beginning and end of the experiment (189.1 ± 0.8 and 211.1 ± 0.8 d of age, respectively). Carcass weights and tissues were collected at harvest. There were no treatment-based differences in growth, carcass, liver, or reproductive tissue weights. Histological analyses revealed differences based on treatment and the interaction between treatment and luteal status. The thickness of the ampullary muscularis declined with ZEN exposure (P < 0.05), while the isthmic epithelial cell height (P < 0.01) and uterine endometrial thickness (P < 0.02) increased. Interestingly, the thickness of the isthmic muscularis, uterine myometrium, and epithelial cell height only differed in the presence of a corpus luteum. Uterine epithelial cell height in the luteal phase was lowest in ZEN-7 pigs (P < 0.01). The isthmic muscularis in the luteal phase was thinner in pigs from both ZEN treatments (P < 0.01). Conversely, the luteal-stage myometrium was thicker in pigs from both ZEN treatments (P < 0.01). The discovery of these tissue-based differences during the luteal phase is particularly concerning since this corresponds with the time when embryos would be affected by the functional competency of the oviduct and uterus. The results of this work demonstrate that short-term consumption of ZEN produces microscopic, but not macroscopic alterations in reproductive organs which are likely to have negative effects on their subsequent function and that these differences persist even after ZEN consumption ceases. Taken together, these results indicate that it is insufficient to rely solely on outwardly visible symptoms as indicators of zearalenone exposure, as detrimental effects on reproductive tissues were found in the absence of phenotypic and morphologic changes.

Sunflower Cake from the Biodiesel Industry in the Diet Improves the Performance and Carcass Traits of Nellore Young Bulls.

We aimed to determine the optimal inclusion level of sunflower cake (0, 90, 180, and 270 g/kg total DM) as a partial replacement of soybean meal and corn ground in young bulls' diets by examining nutrient intake and digestibility, ingestive behavior, nitrogen balance, metabolic serum profile, growth performance, and carcass traits. Thirty-two intact Nellore bulls (BW 374 ± 42.5) were distributed in a completely randomized design. The experiment lasted 90 days. The final BW of the animals was 515.25 ± 24.7. There was a linear decrease effect in the intake of DM, crude protein and nonfibrous carbohydrates, eating and rumination efficiency, N-urinary, N-total excretion, and blood urea nitrogen. Sunflower cake did not affect the NDF digestibility, nitrogen (N)-fecal excretion, blood metabolites, Longissimus lumborum muscle area, or subcutaneous fat deposition. There were linear and quadratic effects on the eating and rumination time, microbial protein production and efficiency, gamma-glutamyl transferase and cholesterol serum concentrations, and muscle carcass tissue. There was a quadratic effect on ether extract intake, final BW, and total gain with the inclusion of sunflower cake in the young bull's diet. The replacement of soybean meal and corn ground with sunflower cake at the level of 90 g/kg of DM in the diet of young bulls is recommended because it reduces the DM intake and digestibility, increases microbial protein synthesis and muscle tissue deposition, and consequently improves the performance, feed efficiency, and carcass traits.

In fat-tailed sheep, variation of energy intake affected growth performances, carcass muscle and tail fat, without modifying carcass fat: A meta-analysis

The study aimed to evaluate, using meta-analysis, average daily gain (ADG), carcass tissue composition (carcass muscle and carcass adipose tissue (CAT)), internal fat (kidney and mesenteric fats) and tail fat responses to metabolizable energy intake (MEI) for fat-tailed lambs. Data from 31 international publications representing 78 treatments were analyzed. Breeds were characterized according to their precocity (Early and Moderate-Early) and maturity stage (Young, Intermediate and Adult). The results showed that each MEI increase by 1 MJ/d/kg LW was accompanied by 12.02 g/d/kg LW ADG and 0.14 kg/kg LW carcass muscle. For fats, only tail fat varied with MEI. For an increase of 1.00 MJ/d/kg LW MEI, fat tail increased by 0.16 kg/kg LW and the response of tail fat to MEI was higher for Early than for Moderate-Early lambs and for adult lambs than for young ones. The variation of carcass tissue composition to ADG changes was also established. Carcass muscle increase by 0.01 kg/kg LW and CAT increase by 0.014 kg/kg LW for each 1.00 g/d/kg LW increment of ADG. According to ADG change, carcass muscle was higher for young lambs whereas CAT was higher for adult lambs. For fats, only tail fat increase with CAT and each 1.00 kg/kg LW increase of CAT was accompanied by 0.33 kg/kg LW tail fat. The slope was higher (P = 0.002 ) for adult lambs (0.83 kg/kg LW) than for young lambs (0.28 kg/kg LW). Tail fat seemed to be an indicator of precocity in sheep and its higher response to energy increment confirm his role as an energy reserve for fat tailed sheep reared in harsh conditions. It is also very interesting to note that for sheep up 62 % of adult weight, the MEI increment increased ADG, carcass muscle, tail fat, without affecting carcass fat.

Identifying the origin of lead poisoning in white-backed vulture (Gyps africanus) chicks at an important South African breeding colony: a stable lead isotope approach.

Elevated lead levels in scavenging raptors can originate from a variety of environmental and anthropogenic sources, including soil, water, mining activities and legacy lead from leaded fuel, but has mostly been attributed to fragments of lead-based ammunition embedded in the tissues of carcasses. To identify the origins of lead in the tissues of white-backed vulture (Gyps africanus) chicks at Dronfield Nature Reserve, South Africa, we used MC-ICP-MS to compare the isotopic composition of lead in blood samples to those of soil in the chicks' immediate environment, different mining activities in South Africa and lead ammunition commonly used in hunting and game management practices. The isotopic ratios in vulture blood samples ranged widely (207Pb/206Pb: 0.827-0.911), but fell within those measured for ammunition (0.761-0.938). Dronfield water can be excluded as a significant source, as the lead concentration for water was below detection limits. Uranium, coal, atmospheric Pb, legacy Pb from fuel and Pb mining can also be excluded as significant sources, based on the limited overlap with Pb isotopic ratios measured in vulture blood. Whereas 55% of chicks we sampled displayed isotopic ratios consistent with Dronfield soil, the low local Pb concentration and the low extractable Pb levels in South African soil in general, imply that soil Pb is unlikely the major source of Pb in WBV chicks, especially in birds with elevated blood Pb levels, i.e. > 20µg/dL. Our results, when considered in the context of vulture feeding ecology and low Pb levels in non-scavenging birds in South Africa, imply the major source of elevated Pb levels in WBV chicks to be fragments of lead-based ammunition embedded in the carrion fed to them by their parents.