Fatty acid profiles and iodine value correlations between 4 carcass fat depots from pigs fed varied combinations of ractopamine and energy

A total of 54 finishing barrows (initial BW = 99.8 ± 5.1 kg; PIC C22 × 337) reared in individual pens were allotted to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of treatments with 2 levels of ractopamine (0 and 7.4 mg/kg) and 3 levels of dietary energy (high: 3,537, medium: 3,369, and low: 3,317 kcal/kg of ME) to determine the effects of feeding ractopamine and various dietary energy levels on the fatty acid profile of 4 carcass fat depots (jowl, belly, subcutaneous loin, and intramuscular) and the predictive relationships of calculated iodine value (IV) between these 4 fat depots. Carcasses were sampled for fat tissues at the anterior tip of the jowl, posterior to the sternum on the belly edge, three-quarters the distance around the LM (subcutaneous fat; SC), and within the LM (intramuscular fat; IMF). Feeding ractopamine diets reduced (P < 0.05) total SFA in SC and IMF and increased (P = 0.04) total MUFA in SC. Also, feeding ractopamine diets increased (P < 0.01) the IV of IMF. Total MUFA of belly fat was reduced (P < 0.05) when the low-energy diet was fed compared with the high-energy diet. Jowl fat total MUFA was reduced (P < 0.05) and total PUFA was increased (P < 0.05) when the medium-energy diet was fed compared with the high- and low-energy diets. Iodine values, independent of treatment, were 60.97, 64.51, 55.59, and 58.26 for belly, jowl, IMF, and SC fat depots, respectively. The IV correlations within fat depots were not consistent across dietary treatments because of the effect of treatments on carcass fatty acid characteristics. Feeding ractopamine diets shifted the fatty acid profile from SFA to MUFA in the SC depot. Feeding ractopamine diets did not change belly fat profiles, thus avoiding the potential negative effect of softening belly fat, which is detrimental to processing value. The IV of one fat depot may not be a good indication of IV of other fat depots because of weak correlation coefficients and the apparent influence of dietary treatment.     

Prediction of fat percentage within marbling score on beef longissimus muscle using 3 different fat determination methods

Consumers are concerned with fat consumption from meat products, and the ability to determine fat has changed with recent technological advances. The objective of this study was to predict fat percentage within marbling scores and compare 3 fat analysis procedures. Steaks (n = 119) were selected by USDA grading system using an E + V Vision Grading camera at a commercial beef plant during 1 d. Two samples per carcass were cut from the 13th rib, both sides, and transported to the University of Missouri meat laboratory. The sample from the right side of the carcass was allotted to Warner-Bratzler shear force, and the sample from the left side, which was graded by the camera, was allotted to fat extraction. Warner-Bratzler shear force samples were cut into 2.54-cm steaks and aged for 14 d. Steaks allotted to fat extraction were trimmed of all external fat and twice ground using 8- and 4-mm grinding plates. The finely ground beef was then split into its allotted fat-extraction methods. The 3 methods used in fat extraction were 2:1 chloroform/methanol (Folch), ether-extractable fat (ether), and microwave drying and nuclear magnetic resonance (CEM). Warner-Bratzler shear force values were not different between marbling scores (P > 0.05). Regardless of fat extraction method, fat percentage increased as marbling score increased (P < 0.05). All regression equations for fat percentage, regardless of extraction method, were linear. Prediction equation for fat percentage using CEM was -3.46 + 0.016 (marbling score), R(2) of 0.824 (P < 0.0001). Prediction equation for fat percentage using ether was -3.08 + 0.017 (marbling score), R(2) of 0.859 (P < 0.0001). Prediction equation for fat percentage using Folch was -3.42 + 0.019 (marbling score), R(2) of 0.816 (P < 0.0001). When the CEM, Folch, and ether methods were compared, CEM and Folch regression lines had different slopes (P < 0.05). The slope of the regression line for ether was not different (P > 0.05) from CEM or Folch. Overall, ether is the most accurate method based on the R(2) value, but CEM is environmentally safe and the fastest method for determining total crude fat percentage.     

A new splash cup to measure the kinetic energy of rainfall

Splash cups have long been successfully used for both the quantification of kinetic energy of rainfall and the detachability of soil particles by rainfall impact, the so‐called “splash erosion”. Measurements of kinetic energy, however, have been difficult to operate in the field especially in remote areas, on steep slopes, and in forests since boundary conditions need to be controlled precisely. This paper introduces a new splash cup based on Ellison's archetype that reliably and accurately measures kinetic energy as a function of sand loss under a large variety of conditions. The Tübingen splash cup (T splash cup) is relatively easy to operate under harsh field conditions, and it can be used in experimental designs with a large number of plots and replications at reasonably low costs. The cup is constructed from plastic laboratory flasks and plastic pipes from water‐supply equipments. The unit sand is held by a removable carrier system that can easily be replaced in the field. The splash cups have been calibrated in combination with a laser distrometer using a linear regression function with r² = 0.98. They measure kinetic energy over a wide range of rainfall intensities from 0.6 to 40 L m^–2 h^–1. Kinetic energy per area varies between 10 and 250 J m^–2. Two years of field test measurements in a subtropical forest ecosystem in China proved the reliability, durability, and usability of our new splash cups and allowed detecting differences in kinetic energy between different tree species and biodiversity levels.     

Genetically transformed maize plants from protoplasts

Genetically transformed maize plants were obtained from protoplasts treated with recombinant DNA. Protoplasts that were digested from embryogenic cell suspension cultures of maize inbred A188 were combined with plasmid DNA containing a gene coding for neomycin phosphotransferase (NPT II) next to the 35S promoter region of cauliflower mosaic virus. A high voltage electrical pulse was applied to the protoplasts, which were then grown on filters placed over feeder layers of maize suspension cells (Black Mexican Sweet) and selected for growth in the presence of kanamycin. Selected cell lines showed NPT II activity. Plants were regenerated from transformed cell lines and grown to maturity. Southern analysis of DNA extracted from callus and plants indicated the presence of the NPT II gene.     

Use of canola oil in the feed of larval and juvenile goldfish, Carassius auratus (L.)

Goldfish were used as a model for the evaluation of canola oil as a lipid source in the feeds of larval and juvenile cyprinids. Goldfish larvae were raised from hatching until 24 weeks of age on diets containing cod liver oil. canola oil or a mixture of the two oils as the lipid source. Survival, weight gain and weight-length relationship did not differ among groups of fish fed the three diets. Carcass fatty acid profiles largely reflected those of the diets except that carcasses of fish fed canola oil contained long chain (n-3) and (n-6) polyunsaturated fatty acids (PUFA) that are not found in canola oil. This indicates that goldfish are capable of producing these fatty acids from 18-carbon precursors. The flesh of fish fed canola oil would be inferior for human nutrition to that offish fed marine oils, due to lower (n-3) PUFA levels. However, the results do indicate that canola oil has good potential as a lipid source in larval cyprinid diets.     

Perspective article: Simulation models for semi‐arid rangelands of southern Africa

Abstract

In semi‐arid regions, the effects of grazing or sparing management on natural communities of long‐lived plants generally take decades to become evident. Event‐driven dynamic behaviour, unpredictable and low rainfall, and complicated interactions between species make it difficult to gather sufficient understanding of vegetation dynamics to be able to develop guidelines for sustainable management. Simulation models that consider the essential processes that determine vegetation dynamics offer scope for quantitatively exploring long‐term vegetation dynamics of arid and semi‐arid rangelands. In this paper we review three models that were aimed to provide an understanding of the vegetation dynamics and management of different typical vegetation types in South Africa, including the Karoo shrubland, the shrub‐grassland of the southern Kalahari, and pure semi‐arid grasslands.     

Effects of high fat,modified wet,corn distiller's grains plus solubles on beef steer performance and carcass characteristics

Corn distiller's grains plus solubles (DGS) have become a common replacement for shelled corn in diets of finishing steers. Numerous studies have evaluated DGS inclusion, both wet (WDGS) and dry (DDGS), into feedlot diets with conflicting reports on feedlot performance and subsequent meat quality. Many authors have failed to describe the nutrient composition of the DGS utilized in their studies making it difficult to determine why different studies have different results. The objective of this study was to evaluate the feedlot performance and subsequent meat quality characteristics of steers fed high fat (10.36±0.72%), modified wet corn distiller's grains plus solubles (HWDGS) at 0, 25, 40, and 70% of the diet dry matter (DM). Angus cross steers (n=240; 335±55 kg) were blocked by source and stratified within block (3 blocks) by body weight (BW) to 32 treatment pens containing either 6 or 10 steers/pen. Pens within block were randomly assigned to one of four diets containing 15% corn silage: (1) 76.9% shelled corn, 6.4% soybean meal 1.5% limestone, 0.2% premix (0 HWDGS); (2) 25.0% HWDGS, 58.20% shelled corn 1.6% limestone, 0.2% premix (25 HWDGS); (3) 40.0% HWDGS, 42.74% shelled corn 2.06% limestone, 0.2% premix (40 HWDGS); (4) 70.0% HWDGS, 12.30% shelled corn 2.5% limestone, 0.2% premix (70 HWDGS). Target BW at harvest was 591 kg±23 kg with 121 steers harvested on day (d) 161 and 117 steers on d 224. Hot carcass weight and liver abscess scores were recorded on d of harvest. Longissimus muscle area, rib fat thickness, marbling score, and kidney, pelvic and heart fat were measured after a 24 h chill. No significant differences were observed between treatments regarding average daily gain (ADG) or BW. Steers fed 0 HWDGS had significantly lower average daily feed intake (ADFI) than steers fed HWDGS and the response was quadratic at lower ADFI. Steers fed 70 HWDGS had lower (P<0.05) dry matter intake (DMI) compared to steers fed lower HWDGS concentrations. Steer gain to feed ratio (G:F) was significantly higher for steers fed 70 HWDGS compared to 0, 25, or 40 HWDGS with a quadratic response at higher % HWDGS diets. Mean United States Department of Agriculture (USDA) quality grade was average choice. Mean USDA yield grade was 3.0. Steers fed 70 HWDGS had significantly smaller rib eye areas and a linear trend (P=0.08) to have lower USDA quality grades compared to steers fed lower HWDGS inclusion rates. Increasing dietary HWDGS increased polyunsaturated fatty acid (PUFA) and PUFA/saturated fatty acid concentrations in intramuscular fat with both a linear and quadratic effect. High fat modified WDGS can be fed up to 70% of diet DM without compromising feedlot performance, carcass characteristics, or meat quality.     

The critical importance of an undammed river segment to the reproductive cycle of a migratory Neotropical fish

Biotelemetry, ichthyoplankton and genetic data can provide detailed information about the migratory dynamics and reproductive cycle of freshwater fishes. However, few studies have combined these techniques in Neotropical systems. The objective of this study was to examine the migratory and reproductive dynamics of Prochilodus costatus in the São Francisco River watershed, south‐east Brazil, by comparing the ecological importance of two rivers to the species, an undammed segment of the São Francisco River and a dammed segment of one of its main tributaries, the Pará River. In total, 215 fish were radio‐tagged over three years (2014–16). Eggs and larvae were sampled at seven locations and analysed by PCR to identify Prochilodus spp. ichthyoplankton. Most radio‐tagged individuals (97%) used the undammed segment of the São Francisco River as spawning migration route, even those captured and released in the Pará River. Fish migrated to spawn from late September to late November with the arrival of the rains and returned to feeding sites from December to May after spawning. The highest densities of fish eggs and larvae were recorded in the upper reaches of the São Francisco River during months of peak river discharge. Returning fish showed high fidelity to sites occupied before spawning migration. Fish spent roughly 71% of the year at feeding sites, 25% at spawning sites and 4% moving between them. This study provides novel information about the migratory dynamics of Neotropical fishes and underscores the key role of undammed river segments for the conservation of Neotropical migratory fish species.     

Sex-based differences in fatty acid composition of adult walleye

Differences in reproductive strategies of male and female fishes are presumably accompanied by differences in nutrient allocation and predicted to lead to divergence in body composition between the sexes. We compared patterns of variation in fatty acid profiles of lipids extracted from ova, liver, muscle and visceral fat between mature male and female walleye (Sander vitreus) sampled from two wild spawning stocks. Fatty acid profiles differed significantly among body tissues in both males and females, with the strongest contrast between muscle and visceral fat. Significant differences in fatty acid composition between the sexes were found in liver, muscle and visceral fat tissues. Variation among sexes and populations was greater in liver than in the other tissues. Female livers had lower relative abundances of palmitic acid (PA, 16:0) and oleic acid (OA, 18:1(n-9)), and higher relative abundances of arachidonic acid (ARA, 20:4(n-6)), eicosapentaenoic acid (EPA, 20:5(n-3)) and docosahexaenoic acid (DHA, 22:6(n-3)) compared to male livers. In addition, female muscle had higher relative abundance of OA and lower relative abundance of DHA compared to male muscle. Our results illustrate the differential effects of reproductive demands on the biochemical composition of males and females and have implications for the analysis of fatty acid profiles in studies of wild fish populations.