Biological Control of Citrus Huanglongbing with EB92-1, a Benign Strain of Xylella fastidiosa.

Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus, is currently the most destructive disease of citrus and threatens production in all affected areas. There is no cure. Benign Xylella fastidiosa strain EB92-1 provided good control of Pierce's disease of grapevine by inducing host resistance; therefore, we evaluated the strain for the biological control of HLB in citrus. Treatment was by injection into the trunk of the trees. Strain EB92-1 was shown to colonize citrus and provided control of HLB by reducing both the incidence of symptomatic trees and the percentage of trees with severe symptoms in three separate trials. All trees were positive by quantitative PCR (qPCR) for Candidatus Liberibacter asiaticus at the start of the trials, and treatment did not eliminate the bacterium. In a trial of asymptomatic mature trees, a single treatment with EB92-1 reduced the incidence of trees with symptoms through 18 months after treatment and reduced the incidence of trees with severe symptoms through 3 years. In mature trees that had 60% incidence of mild HLB symptoms at trial initiation, percentage of trees with symptoms and trees with severe symptoms continued to develop in both the untreated and in the EB92-1-treated trees for 12 months. However, retreatment at 9 and 20 months prevented the development of additional severe symptoms in the EB92-1-treated trees throughout the remainder of the 5-year trial. In 2-year-old trees, incidence of trees with HLB symptoms was higher in the untreated trees than in the treated trees throughout the 6 years of the trial, reaching 90% in the untreated versus 50% in the treated. After 6 years, severity of symptoms was much lower in the EB92-1-treated trees, only 3% of the treated trees had become unproductive compared with 18% of the untreated. In 2020, the reduction in HLB severity resulted in approximately twice as much yield in the treated trees as in these untreated 8-year-old trees. X. fastidiosa strain EB92-1 proved to be efficacious for the control of HLB symptoms in both mature trees and newly planted young trees, but trees may need to be retreated yearly for at least the first 2 to 3 years.

Increasing omega-3 levels in meat from ruminants under pasture-based systems.

This review discusses the importance of red meat from ruminants as a source of omega-3 (n-3) fatty acids (FAs) for human life in the context of the contribution of animals to human welfare. Red meat is a valuable food commodity for human life because it is naturally rich in key nutrients such as protein, trace elements, vitamins and essential FAs. In developed countries and high socio-economic groups from developing countries, red meat intake is greater than that of oily fish, owing to availability, preference and affordability. Omega-3 FA concentration is higher in red meat (beef, lamb and mutton) than in white meat (pork, poultry and turkey), due to the fibre types present in muscle tissues and the specialised digestive systems of ruminants. There is mounting evidence that regular consumption of n-3 FAs is beneficial for growth and development as well as the health and welfare of humans of all ages. The dietary background of ruminants significantly influences the concentration of n-3 FAs in red meat. Meat from forage- or grassfed ruminants has a greater concentration of n-3 FAs than that from their feedlot or grain-fed counterparts and can also offer a favourable n-6:n-3 ratio in the meat. Scientific literature shows that the advantages of consuming n-3 FAs enriched meat (foods) outweigh the disadvantages.

Dans le cadre de l'analyse de la contribution des animaux au bien-être de l'homme, les auteurs examinent l'importance pour l'alimentation humaine des acides gras oméga-3 présents dans la viande rouge provenant de ruminants. La viande rouge est une denrée alimentaire précieuse pour l'organisme humain, étant naturellement riche en plusieurs nutriments majeurs tels que protéines, oligo-éléments, vitamines et acides gras essentiels. Dans les pays développés et dans les classes aisées au plan socio-économique des pays en développement, la consommation de viande rouge dépasse celle de poissons gras pour des raisons de disponibilité, de préférence et de prix. La teneur en acides gras oméga-3 est plus élevée dans les viandes rouges (boeuf, agneau et mouton) que dans les viandes blanches (porc, volaille et dinde) du fait des caractéristiques des fibres des tissus musculaires des ruminants et de leur système digestif spécialisé. Il y a de plus en plus d'indices démontrant qu'une consommation régulière d'acides gras oméga-3 est bénéfique pour la croissance et le développement ainsi que pour la santé et le bien-être de l'être humain à tous les âges de sa vie. Le contexte de l'alimentation des ruminants influence de manière significative la teneur en acides gras oméga-3 de la viande rouge. La viande issue de ruminants nourris de fourrage ou à l'herbe présente une concentration plus élevée d'acides gras oméga-3 que celle de leurs homologues des parcs d'engraissement ou nourris au grain, ainsi qu'un ratio oméga 6/oméga-3 favorable. La littérature scientifique montre que la consommation de viandes (ou autres aliments) riches en acides gras oméga-3 apporte plus de bénéfices que d'inconvénients.

Considerando la cuestión desde el ángulo de la contribución de los animales al bienestar humano, los autores examinan la importancia que reviste para la vida humana la carne roja de rumiante como fuente de ácidos grasos omega-3 (n-3). Por su elevado contenido natural en nutrientes fundamentales como proteínas, oligoelementos, vitaminas y ácidos grasos esenciales, la carne roja es un artículo alimentario de gran valor para la vida humana. En los países desarrollados, al igual que entre las élites socioeconómicas de los países en desarrollo, la ingesta de carne roja es superior a la de pescado azul, por razones de disponibilidad, preferencia y asequibilidad. Por los tipos de fibra presentes en el tejido muscular de los rumiantes y por el carácter especializado de su sistema digestivo, la concentración de ácidos grasos omega-3 es mayor en la carne roja (bovinos y ovinos) que en la carne blanca (cerdo, pollo y pavo). Cada vez hay más datos demostrativos de que el consumo regular de ácidos grasos n-3 es beneficioso para el crecimiento, el desarrollo, la salud y el bienestar de las personas a cualquier edad. El tipo de alimentación de un rumiante influye sensiblemente en la concentración de ácidos grasos n-3 que presentará su carne: la carne de rumiantes que han forrajeado o pastado en campos de hierba tiene mayor concentración de esos ácidos grasos que la de sus homólogos procedentes de establos de engorde o alimentados con grano, además de presentar en ocasiones una proporción más favorable entre n-6 y n-3. Los estudios científicos publicados ponen de relieve que el consumo de carne (u otros alimentos) enriquecida en ácidos grasos n-3 tiene más ventajas que inconvenientes.

Rickettsia-like Bacterium Associated with Pierce's Disease of Grapes.

A pleomorphic bacterium was observed by electron microscopy in grape plants infected with Pierce's disease. The organism was located in xylem tissue, and its occurrence was closely associated with symptoms of Pierce's disease. The bacterium resembled a rickettsia in morphology, in its failure to grow on cell-free media, and in its sensitivity to tetracycline antibiotics.

First Report of Bacterial Leaf Scorch Caused by Xylella fastidiosa on Southern Highbush Blueberry in Florida.

In May of 2008, samples of southern highbush blueberry (interspecific Vaccinium corymbosum hybrids) exhibiting marginal leaf necrosis were collected at a farm in Interlachen, FL. The cv. Star showed severe leaf scorch, partial defoliation, and a generally unthrifty growth structure of many thin twigs as has been observed in Georgia (1). The block of Star plants was approximately 10 years old and incidence of the disease was 100%. The grower reported the planting had become increasingly unproductive in the most recent 4 to 5 years. Plants of the cv. Windsor also showed scorch symptoms and yellow-to-red discoloration of leaves. Proportionally fewer Windsor plants showed disease symptoms than Star plants and the disease was not as severe on this cultivar on the basis of visual estimates at the time. Each sample consisted of 5 to 10 cuttings of spring wood with attached leaves showing marginal necrosis taken from a single plant. Three samples, two from Star plants and one from a Windsor plant, were divided into two subsamples each. One subsample was submitted to Agdia for Xylella fastidiosa double-antibody sandwich (DAS)-ELISA assay (TSE XF; Agdia Inc., Elkhart IN). All three samples were reported as positive for X. fastidiosa by DAS-ELISA. A number of asymptomatic plants from this farm and other additional farms were tested in the same manner and results were negative. The other subsample was used for isolation of the causal bacterium. Petioles and main veins from symptomatic leaves were surface disinfested in 1% sodium hypochlorite, cut into segments (0.5 cm), and squeezed with forceps or pliers. Sap that exuded from the segment was blotted directly onto periwinkle wilt medium (2). Bacterial colonies consistent in morphology with X. fastidiosa that were DAS-ELISA positive were obtained from all three samples. One isolate from each sample was inoculated into four Star plants each with the pin-pricking method (3). Leaf scorch symptoms were first observed 8 weeks after inoculation. By 12 weeks after inoculation, all plants inoculated with the three isolates had developed symptoms, including defoliation. Plants inoculated without bacteria showed no symptoms. X. fastidiosa was reisolated from symptomatic plants. Bacterial leaf scorch is an important emerging disease that threatens the southern highbush blueberry industry in the south. On certain cultivars like Star, the potential to reduce yield appears to be great. Differences between cultivars are likely, but have not yet been explored. Additional research is needed into the epidemiology of the disease and potential vectors of pathogen transmission. References: (1) C. Chang et al. HortScience 44:413, 2009. (2) M. Davis et al. Curr. Microbiol. 6:309, 1981. (3) D. L. Hopkins et al. Phytopathology 75:713, 1985.

Alternating frequency to increase the response to stimulation from medium voltage electrical stimulation and the effect on objective meat quality.

The use of alternating frequencies during stimulation can increase stimulation response of a medium voltage electrical stimulation unit (MVS) by increasing the rate of pH decline. Various combinations of frequency modulation were tested in experiment 1 to determine the treatment resulting in the greatest stimulation response; the lowest initial pH, fastest rate of pH decline, highest temperature at pH 6 and the highest number of carcasses with a pH of 6 by 25(o)C and the treatment achieving the highest number of carcasses in the pH temp window (temperature at pH 6 between 18-25(o)C). The objective meat quality of these treatments compared to an unstimulated treatment was tested in experiment 2. Modulating the frequency (Hz) across the 6 segmented electrodes of the MVS by 10, 15, 25, 10, 15, 25Hz (Treatment 6, using a pulse width: 2.5ms, current: 1A) resulted in the greatest stimulation response. This treatment may be suitable for abattoirs that hot bone sheepmeat and require fast pH declines to ensure minimal cold shortening of meat. However, this treatment did not result in the tenderer meat despite the higher stimulation response. This treatment may have induced a greater number of contractions overall and therefore a greater pH decline response but resulted in less myofibrillar disruption compared to the other treatments due to a concomitant decreased force of contraction thus reducing potential tenderisation. Maintaining a constant frequency of 15Hz (Treatment 1; pulse width: 2.5ms, current: 1A) resulted in a higher number of carcasses in the pH temp window required (temperature at pH 6 between 18-25(o)C) in part A (P<0.05) and in addition to the higher tenderness levels this treatment may be more appropriate to satisfy the overall demands of abattoirs using these systems. This paper has also demonstrated electrical stimulation results in tenderer meat compared to unstimulated meat even after 30d of ageing (2.53±0.4 compared to 2.85±0.1 for the loin (M. longissimus thoracis et lumborum) (P<0.01) possibly due to a protective benefit of stimulation on meat tenderness. Overall, no detrimental effects of modulating frequency were observed on drip loss or retail colour display despite a greater rate of colour change observed with the modulated frequency treatment and the longer aged product.

Particle size analysis of lamb meat: Effect of homogenization speed, comparison with myofibrillar fragmentation index and its relationship with shear force.

The impact of homogenization speed on Particle Size (PS) results was examined using samples from the M.longissimus thoracis et lumborum (LL) of 40 lambs. One gram duplicate samples from meat aged for 1 and 5days were homogenized at five different speeds; 11,000, 13,000, 16,000, 19,000 and 22,000rpm. In addition to this LL samples from 30 different lamb carcases also aged for 1 and 5days were used to study the comparison between PS and myofibrillar fragmentation index (MFI) values. In this case, 1g duplicate samples (n=30) were homogenized at 16,000rpm and the other half (0.5g samples) at 11,000rpm (n=30). The homogenates were then subjected to respective combinations of treatments which included either PS analysis or the determination of MFI, both with or without three cycles of centrifugation. All 140 samples of LL included 65g blocks for subsequent shear force (SF) testing. Homogenization at 16,000rpm provided the greatest ability to detect ageing differences for particle size between samples aged for 1 and 5days. Particle size at the 25% quantile provided the best result for detecting differences due to ageing. It was observed that as ageing increased the mean PS decreased and was significantly (P<0.001) less for 5days aged samples compared to 1day aged samples, while MFI values significantly increased (P<0.001) as ageing period increased. When comparing the PS and MFI methods it became apparent that, as opposed to the MFI method, there was a greater coefficient of variation for the PS method which warranted a quality assurance system. Given this requirement and examination of the mean, standard deviation and the 25% quantile for PS data it was concluded that three cycles of centrifugation were not necessary and this also applied to the MFI method. There were significant correlations (P<0.001) within the same lamb loin sample aged for a given period between mean MFI and mean PS (-0.53), mean MFI and mean SF (-0.38) and mean PS and mean SF (0.23). It was concluded that PS analysis offers significant potential for streamlining determination of myofibrillar degradation when samples are measured after homogenization at 16,000rpm with no centrifugation.

Polyunsaturated fats in meat from Merino, first- and second-cross sheep slaughtered as yearlings.

This study examined the level of long chain omega-3 and omega-6 polyunsaturated fats, the ratio of polyunsaturated fat to saturated fat (PUFA/SFA) and the ratio of omega-6 to omega-3 (n-6/n-3) fat in sheep grown under grazing conditions in Australia. The sheep genotypes used were Poll Dorset(growth)×Border Leicester Merino (PDg×BLM), Poll Dorset(growth)×Merino (PDg×M), Poll Dorset(muscling)×Merino (PDm×M), Border Leicester×Merino (BL×M) and Merino×Merino (M×M). Loin muscles (Longissimus lumborum) collected from 40 ewe and wether sheep slaughtered at 14months of age were processed for fatty acid determination. After frozen storage, 20g samples were minced and a 7g homogenate was processed for muscle lipid extraction using a chloroform:methanol (2:1) procedure. There was an increase in PUFA/SFA as the proportion of Merino genetics increased in the progeny (second-cross

Genetic variation in colour stability traits of lamb cuts under two packaging systems.

Data from samples of longissmus lumborum (LL) and semimembranosus (SM) muscles from 391 lamb carcasses, which had been packaged in overwrap (OW) or high oxygen modified atmosphere packaging (MAPO2) systems and then subjected to simulated retail display, were used to estimate genetic variation for colour stability traits of lamb meat as a step in identifying a trait for genetic evaluation. Traits included the ratio of the reflectance of light at wavelengths of 630 nm and 580 nm (oxy/met) measured at a single time point at the end of the display period (day 3 under OW; day 8 under MAPO2) and the predicted time for oxy/met to reach a benchmark value. Under OW and MAPO2, the measures of meat colour stability of the LL tended to be of moderate heritability (0.09-0.29), but for the SM were of low heritability (0-0.10). Improving retail colour stability of lamb loins through selection of genetically superior animals may be better based on measurement of oxy/met.

Comparison of a grain-based diet supplemented with synthetic vitamin E versus a lucerne (alfalfa) hay-based diet fed to lambs in terms of carcass traits, muscle vitamin E, fatty acid content, lipid oxidation, and retail colour of meat.

Dietary supplementation of vitamin E (VitE) in a synthetic or natural form was examined. Forty-eight lambs were assigned (n = 16) to either a grain-based diet at moderate (MOD, 42 mg∙kg-1 VitE as all-rac α-tocopheryl acetate) or supranutritional (SUP, 285 mg∙kg-1 of vitE) levels of synthetic VitE or a lucerne hay-based diet (LUC; 37 mg∙kg-1 VitE) for 8 weeks. Meat from the LUC group had lower muscle n-6 and PUFA levels compared to meat from the MOD and SUP groups. Despite a similar VitE intake, muscle VitE was higher for LUC compared to MOD, while SUP lambs showed the highest VitE. Lipid oxidation did not differ between groups. For fresh meat, redness tended to be higher in LUC fed lambs than the other two groups, but brownness formation was only lower than the SUP group. For aged meat colour stability, redness tended to be higher in lambs fed SUP and LUC, whereas highest browning occurred in the MOD group.

Predicting the composition of lamb carcases using alternative fat and muscle depth measures.

Hot carcase weight (HCW) and the GR tissue depth (total tissue depth over the 12th rib, 110mm from the midline) were measured on 312 crossbred (Poll Dorset×Merino) lambs with a mean live weight of 47kg. At a position 30mm distal to the lumbar-sacral junction, the depth (RMD) of the rump muscles was measured along with subcutaneous fat depth overlaying the m. gluteus medius (RFD). The subcutaneous fat depth over the m. longissimus (loin) at the 12th rib was measured (Fat C), as was the depth and width of the loin cross section (EMD and EMW, respectively). The right side of each carcase was scanned by a dual energy X-ray bone densitometer and fat and lean weight determined and the percentage of lean and fat content in the carcases calculated. HCW alone accounted for 26% of the variation in percentage lean content (LC), with GR measurement being the single best predictor of LC (R(2)=48.1; r.s.d.=1.89). RFD provided a less accurate and precise estimate of LC (R(2)=37.3; r.s.d.=2.07) than either GR or Fat C (R(2)=46.5; r.s.d.=1.92). Inclusion of HCW with either GR or Fat C provided a small improvement in the amount of variation in LC which could be explained. The measurement of breeding animals by ultrasound includes the terms weight, Fat C and EMD. These predictors when combined explained 49% of the variation in LC whereas by comparison measures of weight, RFD and RMD only explained 42% of the variation in LC. The current method of measuring fat depth over the 12th/13th rib is practical and measurement over the rump does not present an advantage based on the results of this study.

The impact of new generation pre-dressing medium-voltage electrical stimulation on tenderness and colour stability in lamb meat.

Previous work identified that a large number of domestic lamb carcases processed in Australia do not meet the recommended pH/temperature window during chilling. New medium voltage electrical stimulation technology has been developed to alleviate this problem. This study used an optimised setting (800mA with a pulse width 0.5ms) to evaluate the effects on meat quality with a focus on tenderness and meat colour. In total 40 (electrically stimulated) and 40 (non electrically stimulated) lambs from 11 lots killed over 2 days were evaluated. There was a significant difference (P<0.05) between stimulation treatments for initial pH, rate of pH decline and the predicted temperature at pH 6.0. There was also a large difference in the number of carcases that met the recommended window (pH of 6.0, between 18 and 25°C), with an average 67.5% of stimulated carcases and 25% of unstimulated carcases meeting or falling just above the recommended window. The stimulation treatment had no significant (P>0.05) effect on sarcomere length or myofibrillar fragmentation index (MFI) of the m. longissimus (LL). After 1day of ageing LL samples from stimulated carcases had a significantly lower (P<0.05) shear force than non stimulated samples, but there was no difference between stimulation treatments after 5 days ageing. However, ageing period did have a significant effect (P<0.001) on both MFI and shear force, such that 5days aged product had higher MFI and lower shear force values. There were minimal effects of stimulation on colour stability.

Meat science from 1976: A history of the journal.

The journal Meat Science was first published in 1976/77 and it initially comprised 4 issues per year. The first issue contained 4 papers and the first volume (4 issues) contained 27 articles, a mixture of papers and research notes. Its growth/popularity increased, and it has continued to thrive and in 2016 of the 1010 papers processed 292 were accepted. Over 90% of the papers published in the first volume were concerned with muscle biochemistry/meat properties. During the last years of the 20th century, meat products and their properties became a far larger proportion of the submissions as did those concerned with nutrition and safety. More recently there has been a resurgence of papers concerned with meat quality. Over the last 40years, the journal has reported on the major developments in meat science research and this paper will discuss both the history of the journal, and aspects of meat research as reflected in its publications. Possible future research trends are also discussed.

The effect of applying a rinse and chill procedure to lamb carcases immediately post-death on meat quality?

The current study examined the effect of vascular rinsing lamb carcases (Rinse & Chill®) with a commercially available isotonic substrate solution (98.5% water; balance: glucose, polyphosphates, and maltose) at 14°C. Thirty, lamb carcases were randomly allocated to receive either the solution (n=15) 25 min post slaughter on a slaughter line or no solution (n=15). There was no apparent effect on the rate of pH decline due to infusion or muscle shortening of the M. longissimus thoracis et lumborum (LL), but there was a more than 50% reduction in toughness (lower shear force) of the LL due to infusion. Infusion resulted in lighter (L*), yellower (b*) LL and this effect was maintained during simulated colour display. There was no impact on redness (a*) of the LL and in fact a critical consumer threshold for redness was not breached on average for infused or non-infused LL. There was no evidence of elevated levels of metmyoglobin formation or lipid oxidation.

Retail colour stability of lamb meat is influenced by breed type, muscle, packaging and iron concentration.

The longissmus lumborum (LL) and semimembranosus (SM) muscles from 391 lamb carcasses, derived from various breed types, were used to investigate the effect of animal/muscle factors, packaging type [over-wrap (OW) or high oxygen modified atmosphere packaging (MAPO2)] and duration of display on redness of meat during simulated retail display. Using statistical models the time required (in days) for redness to reach a threshold value of 3.5 (below this is unacceptable) was predicted. High levels of iron in the SM, but not LL, reduced the time for redness to reach 3.5 by 2-2.6days in MAPO2 and 0.5-0.8days in OW. The greater the proportion of Merino breed type, the shorter was the time for redness to reach the value of 3.5, an effect consistent across muscles and packaging types. In summary, breed type, packaging format, muscle and muscle iron levels had a significant impact on colour stability of sheep meat in oxygen-available packaging systems.

The combined effects of grain supplementation and tenderstretching on alpaca (Vicugna pacos) meat quality.

This study investigated the effects of feeding a mixed grain supplement and tenderstretching (TS) alpaca carcasses on meat quality. A total of 56 castrated 24month old alpacas were divided into two treatments (pasture-only, and pasture plus supplementation). Supplemented groups were fed a mixed grain ration in addition to ad lib pasture for 10weeks. Animals were slaughtered across two kill days (n=28). One half of each carcass was suspended by the pelvis (TS) prior to chilling, and the other half was Achilles tendon hung (AH). After 24h, muscles were removed and aged for 10 and 25d. TS significantly increased sarcomere length and reduced shear force and cooking loss in the m. semimembranosus. This trend was not observed in other muscles including the m. longissimus thoracis et lumborum (LL) and m. psoas major. Ageing period resulted in a marginal improvement in LL tenderness. There is clear evidence that TS improves tenderness in the hindquarter of alpacas.

The use of oxidative stress biomarkers in live animals (in vivo) to predict meat quality deterioration postmortem (in vitro) caused by changes in muscle biochemical components.

This study was conducted to determine whether circulating concentrations of blood isoprostanes can be used as an effective biomarker in lambs to predict degradation of color and/or lipid stability in meat. Lambs ( = 84) were fed diets of either lucerne pasture, annual ryegrass pasture, a commercial feedlot pellet, or a combination of annual ryegrass and feedlot pellet for 8 wk, including a 2-wk adaptation period. Blood isoprostane concentration at wk 0, 4, 6 or 8 of feeding was determined. Blood isoprostane concentration for each animal was then correlated with muscle biochemical components that impact color and/or lipid oxidative status during retail display. This included lipid oxidation levels in muscle assessed by thiobarbituric acid reactive substances and meat redness determined by a HunterLab colorimetric spectrometer. Lambs that consumed the commercial feedlot pellet had a lower muscle vitamin E level (< 0.01) and a greater level of -6 PUFA ( < 0.001) compared with lambs finished on annual ryegrass or lucerne. Lipid oxidation levels were greatest for lambs finished on the feedlot ration, lowest in lambs finished on the ryegrass diet, and intermediate for lambs finished on lucerne and ryegrass-feedlot combination ( < 0.01). After 8 wk of feeding, blood isoprostane concentration was positively correlated with lipid oxidation of meat displayed for 72 h in simulated retail conditions ( < 0.01). There was a negative linear relationship between isoprostane concentration and muscle vitamin E concentration ( = 0.07), lipid oxidation and muscle vitamin E concentration ( < 0.01) but a positive linear relationship between isoprostane concentration and muscle -6 PUFA ( < 0.001) or lipid oxidation and muscle -6 PUFA concentration ( < 0.001). Blood isoprostane concentration and lipid oxidation in meat were influenced by muscle vitamin E and -6 PUFA but not by -3 PUFA. There was no significant relationship observed between blood isoprostane concentration at 0, 4, 6 or 8 wk feeding vs. overall meat color (redness of meat) at 0 and 72 h of display, stored under simulated retail conditions. The results indicate that circulating blood isoprostane concentration can be a useful tool to predict the oxidative status of postmortem meat. Future work will examine the impact of this relationship on meat flavor/aroma deterioration post farm.

The impact of gender and age on the nutritional parameters of alpaca (Vicugna pacos) meat, colour stability and fat traits.

Meat quality parameters for 50 huacaya alpacas, representing three age groups (18, 24 and 36months) and two genders (females and castrated males) were studied. Prior to chilling, samples of m. longissimus thoracis et lumborum (LL) were taken to determine isocitrate dehydrogenase activity and glycogen concentration, and further meat quality samples were taken after 24h. Alpaca meat has low levels (<1%) of intramuscular fat in the LL, m. semimembranosus and m. biceps femoris, but the level in the LL increases with animal age, with levels of desirable polyunsaturated fatty acids (PUFA) ranging from 96.3 to 136.4mg/100g. Lipid oxidisation post retail display ranged from 1.27 to 1.96MDA/kg meat. Colour stability testing indicated alpaca meat was relatively stable during retail display with day of display having no significant effect on lightness (L*), or the 630nm/580nm ratio. These results may relate to the high proportion (76%) of glycolytic and type IIX muscle fibres in LL.

Genetic correlations between wool traits and meat quality traits in Merino sheep.

Genetic correlations between 29 wool production and quality traits and 25 meat quality and nutritional value traits were estimated for Merino sheep from an Information Nucleus (IN). Genetic correlations among the meat quality and nutritional value traits are also reported. The IN comprised 8 flocks linked genetically and managed across a range of sheep production environments in Australia. The wool traits included over 5,000 yearling and 3,700 adult records for fleece weight, fiber diameter, staple length, staple strength, fiber diameter variation, scoured wool color, and visual scores for breech and body wrinkle. The meat quality traits were measured on samples from the and included over 1,200 records from progeny of over 170 sires for intramuscular fat (IMF), shear force of meat aged for 5 d (SF5), 24 h postmortem pH (pHLL; also measured in the , pHST), fresh and retail meat color and meat nutritional value traits such as iron and zinc levels, and long-chain omega-3 and omega-6 polyunsaturated fatty acid levels. Estimated heritabilities for IMF, SF5, pHLL, pHST, retail meat color lightness (), myoglobin, iron, zinc and across the range of long-chain fatty acids were 0.58 ± 0.11, 0.10 ± 0.09, 0.15 ± 0.07, 0.20 ± 0.10, 0.59 ± 0.15, 0.31 ± 0.09, 0.20 ± 0.09, 0.11 ± 0.09, and range of 0.00 (eicosapentaenoic, docosapentaenoic, and arachidonic acids) to 0.14 ± 0.07 (linoleic acid), respectively. The genetic correlations between the wool production and meat quality traits were low to negligible and indicate that wool breeding programs will have little or no effect on meat quality. There were moderately favorable genetic correlations between important yearling wool production traits and the omega-3 fatty acids that were reduced for corresponding adult wool production traits, but these correlations are unlikely to be important in wool/meat breeding programs because they have high SE, and the omega-3 traits have little or no genetic variance. Significant genetic correlations among the meat quality traits included IMF with SF5 (-0.76 ± 0.24), fresh meat color * (0.50 ± 0.18), and zinc (0.41 ± 0.19). Selection to increase IMF will improve meat tenderness and color which may address some of the issues with Merino meat quality. These estimated parameters allow Merino breeders to combine wool and meat objectives without compromising meat quality.

Genetic correlations between wool traits and carcass traits in Merino sheep.

Genetic correlations between 29 wool production and quality traits and 14 whole carcass measures and carcass component traits were estimated from the Information Nucleus of 8 flocks managed across a range of Australian sheep production environments and genetically linked. Wool data were from over 5,000 Merino progeny born over 5 yr, whereas carcass data were from over 1,200 wether progeny of over 176 sires, slaughtered at about 21 kg carcass weight, on average. Wool traits included yearling and adult records for wool weight, fiber diameter, fiber diameter variation, staple strength, scoured color, and visual scores for breech and body wrinkle. Whole carcass measures included HCW, dressing percentage (DP), and various measures of fat depth and eye muscle dimensions. Carcass components were obtained by dissection, and lean meat yield (LMY) was predicted. Heritability estimates for whole carcass measures ranged from 0.12 ± 0.08 to 0.35 ± 0.10 and ranged from 0.17 ± 0.10 to 0.46 ± 0.10 for carcass dissection traits, with no evidence of important genotype × environment interactions. Genetic correlations indicated that selection for increased clean wool weight will result in reduced carcass fat (-0.17 to -0.34) and DP (-0.48 ± 0.15), with little effect on carcass muscle. Selection for lower fiber diameter will reduce HCW (-0.48 ± 0.15) as well as carcass fat (0.14 to 0.27) and muscle (0.21 to 0.50). There were high genetic correlations between live animal measures of fat and muscle depth and the carcass traits (generally greater than 0.5 in size). Selection to increase HCW (and DP) will result in sheep with fewer wrinkles on the body (-0.57 ± 0.10) and barer breeches (-0.74 ± 0.12, favorable), with minor deterioration in scoured wool color (reduced brightness and increased yellowness). Selection for reduced fat will also result in sheep with fewer body wrinkles (-0.42 to -0.79). Increasing LMY in Merinos through selection would result in a large reduction in carcass fat and DP (-0.66 to -0.84), with a smaller increase in carcass muscle and some increase in wool weight and wrinkles. Although no major antagonisms are apparent between the wool and carcass traits, developing selection indexes for dual-purpose wool and meat breeding objectives will require accurate estimates of genetic parameters to ensure that unfavorable relationships are suitably considered. The findings will aid development of dual-purpose wool and meat breeding objectives.

Eating quality of commercially processed hot boned sheep meat.

The aim of this work was to establish consumer perceptions of the eating quality of commercially processed hot boned sheep meat. The eating quality scores for tenderness, flavour, juiciness, and overall liking of grilled m. longissimus thoracis et lumborum (LL) were derived from untrained consumers. The animals used in this experiment were sourced from three different properties and were of various ages, breed, and sex, and had been on various quality pastures. All carcases were subjected to immobilisation, spinal discharge and high voltage electrical stimulation and boned within 2h of slaughter. All LL samples were frozen after boning according to the system applied at the abattoir and samples kept for consumer assessment and measurement of meat quality. The results showed, on average carcases entered rigor at high temperatures with a pH of 5.95 at 29.3°C. With an average sarcomere length of 1.68µm, some shortening was evident and there was a significant difference between lots in sarcomere length (P<0.05). A large percentage (82%) of samples had a pH greater than 5.8 at the time of freezing. All samples taken for shear force analysis exceeded a recommended threshold for acceptable table meat of 49N and there was no significant difference between lots (P>0.05). Only 13.5% of the samples met the 'good everyday' requirement following sensory assessment and there were significant differences between lots for eating quality traits (P<0.05). This work clearly shows that the application of effective electrical stimulation is not sufficient to ensure that hot boned sheep meat will be suitable as a table meat. These findings highlight the need for the inclusion of other intervention techniques.