Effects of fatty acids on meat quality: a review

Intramuscular fat (IMF) content plays a key role in various quality traits of meat. IMF content varies between species, between breeds and between muscle types in the same breed. Other factors are involved in the variation of IMF content in animals, including gender, age and feeding. Variability in IMF content is mainly linked to the number and size of intramuscular adipocytes. The accretion rate of IMF depends on the muscle growth rate. For instance, animals having a high muscularity with a high glycolytic activity display a reduced development of IMF. This suggests that muscle cells and adipocytes interplay during growth. In addition, early events that influence adipogenesis inside the muscle (i.e proliferation and differentiation of adipose cells, the connective structure embedding adipocytes) might be involved in interindividual differences in IMF content. Increasing muscularity will also dilute the final fat content of muscle. At the metabolic level, IMF content results from the balance between uptake, synthesis and degradation of triacylglycerols, which involve many metabolic pathways in both adipocytes and myofibres. Various experiments revealed an association between IMF level and the muscle content in adipocyte-type fatty acid-binding protein, the activities of oxidative enzymes, or the delta-6-desaturase level; however, other studies failed to confirm such relationships. This might be due to the importance of fatty acid fluxes that is likely to be responsible for variability in IMF content during the postnatal period rather than the control of one single pathway. This is evident in the muscle of most fish species in which triacylglycerol synthesis is almost zero. Genetic approaches for increasing IMF have been focused on live animal ultrasound to derive estimated breeding values. More recently, efforts have concentrated on discovering DNA markers that change the distribution of fat in the body (i.e. towards IMF at the expense of the carcass fatness). Thanks to the exhaustive nature of genomics (transcriptomics and proteomics), our knowledge on fat accumulation in muscles is now being underpinned. Metabolic specificities of intramuscular adipocytes have also been demonstrated, as compared to other depots. Nutritional manipulation of IMF independently from body fat depots has proved to be more difficult to achieve than genetic strategies to have lipid deposition dependent of adipose tissue location. In addition, the biological mechanisms that explain the variability of IMF content differ between genetic and nutritional factors. The nutritional regulation of IMF also differs between ruminants, monogastrics and fish due to their digestive and nutritional particularities.

https://researchrepository.murdoch.edu.au/6455/1/fat_content_in_meat%2Dproducing_animals.pdf

Intramuscular fat content in meat-producing animals: development, genetic and nutritional control, and identification of putative markers.

A fresh look at meat flavor

Introduction / Edwin A. Locke and Gary P. Latham -- Goal setting theory, 1990 / Edwin A. Locke and Gary P. Latham -- The economic value of goal setting to employers / Frank L. Schmidt -- Stretch goals : risks, possibilities and best practices / Steve Kerr and Doug LePelley -- Attributions and emotions as mediators and/or moderators in the goal striving process / Marion B. Eberly, Dong Liu, Terence R. Mitchell and Thomas W. Lee -- Feedback, goal setting and task performance revisited / Susan J. Ashford and Kathleen E. M. DeStobbeleir -- Goal commitment / Howard J. Klein, Joseph T. Cooper and Christina A. Monahan -- Goals, goal orientations, strategies and performance / Robert E. Wood, Jennifer Whelan, Victor Sojo and Moureen Wong -- Special goal topics -- Goals and affect / Stefanie A. Plemmons and Howard M. Weiss -- Determinants of goals / Peter A. Heslin and Karyn L. Wang -- The role of self efficacy in goal-based motivation / Albert Bandura --^

New developments in goal setting and task performance.

Social relationships, which are contingent on access to social networks, promote engagement in social activities and provide access to social support. These social factors have been shown to positively impact health outcomes. In the current systematic review, we offer a comprehensive overview of the impact of social activities, social networks and social support on the cognitive functioning of healthy older adults (50+) and examine the differential effects of aspects of social relationships on various cognitive domains. We followed PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, and collated data from randomised controlled trials (RCTs), genetic and observational studies. Independent variables of interest included subjective measures of social activities, social networks, and social support, and composite measures of social relationships (CMSR). The primary outcome of interest was cognitive function divided into domains of episodic memory, semantic memory, overall memory ability, working memory, verbal fluency, reasoning, attention, processing speed, visuospatial abilities, overall executive functioning and global cognition. Thirty-nine studies were included in the review; three RCTs, 34 observational studies, and two genetic studies. Evidence suggests a relationship between (1) social activity and global cognition and overall executive functioning, working memory, visuospatial abilities and processing speed but not episodic memory, verbal fluency, reasoning or attention; (2) social networks and global cognition but not episodic memory, attention or processing speed; (3) social support and global cognition and episodic memory but not attention or processing speed; and (4) CMSR and episodic memory and verbal fluency but not global cognition. The results support prior conclusions that there is an association between social relationships and cognitive function but the exact nature of this association remains unclear. Implications of the findings are discussed and suggestions for future research provided. PROSPERO 2012: CRD42012003248
 .

/pdf/the-impact-of-social-activities-social-networks-social-4llti4e9mz.pdf

The impact of social activities, social networks, social support and social relationships on the cognitive functioning of healthy older adults: a systematic review

We used 69 steers of varying percentage Brahman (B) breeding (0% B, n = 11; 25% B, n = 13; 37% B, n = 10; 50% B, n = 12; 75% B, n = 12; 100% B, n = 11) to study the relationship between carcass traits, the calpain proteinase system, and aged meat tenderness in intermediate B crosses. Calpains and calpastatin activities were determined on fresh longissimus muscle samples using anion-exchange chromatography. The USDA yield and quality grade data (24 h) were collected for each carcass. Longissimus steaks were removed and aged for 5 or 14 d for determination of shear force and 5 d for sensory panel evaluation. Even though some yield grade factors were affected by the percentage of B breeding, USDA yield grades did not differ (P > .15) between breed types. Marbling score and USDA quality grade decreased linearly (P < .01) with increasing percentage of B breeding. Shear force after 5 and 14 d of aging was higher (P < .05) in the 100% B steers than in all other breed types, which were not significantly different. Sensory panel tenderness and connective tissue scores decreased linearly (P < .05) with increasing B breeding. A quadratic effect was also noted for tenderness and connective tissue scores; 37% B steers received the highest scores. A similar response was found in mu-calpain activities; the 37% B steers had the highest activities. Conversely, calpastatin activity increased linearly (P < .01) with increasing percentage B breeding. These data show strong linear relationships between calpastatin activity (positive), marbling score (negative), and percentage B breeding, suggesting a possible combined effect of these traits on aged tenderness of intermediate Brahman crosses.

Carcass characteristics, the calpain proteinase system, and aged tenderness of Angus and Brahman crossbred steers.

Heritabilities and genetic and phenotypic correlations were estimated from feedlot and carcass data collected from Brahman calves (n = 504) in central Florida from 1996 to 2000. Data were analyzed using animal models in MTDFREML. Models included contemporary group (n = 44; groups of calves of the same sex, fed in the same pen, slaughtered on the same day) as a fixed effect and calf age in days at slaughter as a continuous variable. Estimated feedlot trait heritabilities were 0.64, 0.67, 0.47, and 0.26 for ADG, hip height at slaughter, slaughter weight, and shrink. The USDA yield grade estimated heritability was 0.71; heritabilities for component traits of yield grade, including hot carcass weight, adjusted 12th rib backfat thickness, loin muscle area, and percentage kidney, pelvic, and heart fat were 0.55, 0.63, 0.44, and 0.46, respectively. Heritability estimates for dressing percentage, marbling score, USDA quality grade, cutability, retail yield, and carcass hump height were 0.77, 0.44, 0.47, 0.71, 0.5, and 0.54, respectively. Estimated genetic correlations of adjusted 12th rib backfat thickness with ADG, slaughter weight, marbling score, percentage kidney, pelvic, and heart fat, and yield grade (0.49, 0.46, 0.56, 0.63, and 0.93, respectively) were generally larger than most literature estimates. Estimated genetic correlations of marbling score with ADG, percentage shrink, loin muscle area, percentage kidney, pelvic, and heart fat, USDA yield grade, cutability, retail yield, and carcass hump height were 0.28, 0.49, 0.44, 0.27, 0.45, -0.43, 0.27, and 0.43, respectively. Results indicate that sufficient genetic variation exists within the Brahman breed for design and implementation of effective selection programs for important carcass quality and yield traits.

http://www6.compuland.com.br/fazendasantatereza/arquivos/se45-carcass-jas-2002-estimated-genetic-parameters-for-carcass-traits-of-brahman-cattle-pdf_1361529413.pdf

Estimated genetic parameters for carcass traits of Brahman cattle.

We examined memory control beliefs in relation to memory performance and beliefs in the context of goal setting. Control beliefs showed significant effects on performance and self-efficacy. Higher goals were set by high-control younger adults than by older adults and low-control younger adults. Individuals with a high sense of control performed higher and maintained performance over trials regardless of whether they set explicit goals. Those with low control (primarily older adults) performed lower, but they achieved increased performance when motivated by goals. These results emphasized that performance limitations associated with low control can be overcome with goals, even in older adults. As with previous studies, however, younger adults showed a more positive response to goals than older adults.

Aging and Memory Control Beliefs: Performance in Relation to Goal Setting and Memory Self-Evaluation

Heritabilities and genetic and phenotypic correlations were estimated from carcass and beef palatability data collected from Brahman calves (n = 504) born in central Florida from 1996 to 2000. Traits evaluated included Warner-Bratzler shear force (after 7, 14, and 21 d of aging), panel tenderness score, connective tissue amount, juiciness, flavor intensity, and off flavor (after 14 d of aging), percentages of raw and cooked lipids, and milligrams per gram of muscle calpastatin activity. Parameters were estimated using an animal model and derivative-free restricted maximum likelihood procedures. Estimated heritabilities for d 7, 14, and 21 shear force were 0.14,0.14, and 0.06, respectively, indicating that improvement in these traits by selection would be slow. Estimated heritabilities of sensory panel attributes were 0.11, 0.12, 0.05, 0.04, and 0.01 for tenderness, connective tissue amount, juiciness, flavor intensity, and off flavor, respectively. The estimated heritabilities for percentages of raw and cooked lipids, and calpastatin activity were 0.34, 0.17, and 0.07, respectively. Most of the estimated genetic correlations among palatability traits and for palatability traits with fat thickness, marbling score, and loin muscle area were consistent with other estimates from the literature. Results indicated that improvement in tenderness based on selection for favorable shear force, sensory panel tenderness, or calpastatin activity would be slow; therefore, postslaughter intervention programs should also be considered.

Estimated genetic parameters for palatability traits of steaks from Brahman cattle

This research examined the impact of goals on memory and memory beliefs. Older and younger adults completed memory beliefs questionnaires and list recall at baseline. After additional recall trials, the questionnaires were repeated. In Experiment 1, participants were assigned to low challenge or high challenge goals. In Experiment 2, moderate challenge goals were compared to control. In both studies, participants were given a specific goal based on their own performance and received positive feedback for memory gains. Both older and younger adults responded to the goals, showing improved performance across trials, with little change in the control condition. Memory beliefs changed in the moderate and low challenge goal conditions, showing more striking changes for the older groups. These results confirmed that self-regulatory processes related to goal setting can have considerable impact on memory across the adult life span.

R. L. West

Papers

Carcass characteristics, the calpain proteinase system, and aged tenderness of Angus and Brahman crossbred steers.

Estimated genetic parameters for carcass traits of Brahman cattle.

Aging and Memory Control Beliefs: Performance in Relation to Goal Setting and Memory Self-Evaluation

Estimated genetic parameters for palatability traits of steaks from Brahman cattle

Memory performance and beliefs as a function of goal setting and aging.