Adherence and eating experiences differ between participants following a flexitarian diet including red meat or a vegetarian diet including plant-based meat alternatives: findings from a 10-week randomised dietary intervention trial.

Background: Flexitarian, vegetarian and exclusively plant-based diets are increasingly popular, particularly amongst young adults. This is the first randomised dietary intervention to investigate the health, wellbeing, and behavioural implications of consuming a basal vegetarian diet that additionally includes low-to-moderate amounts of red meat (flexitarian) compared to one containing plant-based meat alternatives (PBMAs, vegetarian) in young adults (ClinicalTrials.gov NCT04869163). The objective for the current analysis is to measure adherence to the intervention, nutrition behaviours, and participants' experience with their allocated dietary group. Methods: Eighty healthy young adults participated in this 10-week dietary intervention as household pairs. Household pairs were randomised to receive either approximately three serves of red meat (average of 390 g cooked weight per individual, flexitarian group) or PBMAs (350-400 g per individual, vegetarian group) per week on top of a basal vegetarian diet. Participants were supported to adopt healthy eating behaviours, and this intervention was developed and implemented using a behaviour change framework. Adherence (eating allocated red meat or PBMA, abstaining from animal-based foods not provided by researchers) was continuously monitored, with total scores calculated at the end of the 10-week intervention period. Eating experiences were measured by the Positive Eating Scale and a purpose-designed exit survey, and a food frequency questionnaire measured dietary intake. Analyses used mixed effects modeling taking household clustering into account. Results: The total average adherence score was 91.5 (SD = 9.0) out of a possible 100, with participants in the flexitarian group scoring higher (96.1, SD = 4.6, compared to 86.7, SD = 10.0; p < 0.001). Those receiving red meat were generally more satisfied with this allocation compared to those receiving the PBMAs, even though a leading motivation for participants joining the study was an opportunity to try plant-based eating (35% expressed that their interest in taking part was related to trying plant-based eating). Participants in both intervention groups had increased vegetable intake (p < 0.001), and reported more positive eating experiences (p = 0.020) and satisfaction with eating (p = 0.021) at the end of the 10-week intervention relative to baseline values. Conclusion: Methods to encourage engagement with the trial were successful, as participants demonstrated excellent adherence to the intervention. Observed differences in participants' adherence and experiences between flexitarian and vegetarian groups holds implications for the adoption of healthy, sustainable dietary patterns beyond this study alone.

Generation and identification of kokumi compounds and their validation by taste-receptor assay: An example with dry-cured lamb meat.

Kokumi tastants are small γ-glutamyl peptides (GGP) that enhance flavour in foods. We sought to generate GGP from the meat crusts of dry-cured lamb, an underutilised protein resource, identify these using mass spectrometry, and validate their functional activity using a kokumi-calcium sensing receptor (CaSR) assay. The water-soluble extract (WSE) of meat crust was hydrolysed by protease A (PA) and treated with glutaminase (GA). Fifteen GGP were identified, with 14 being significantly increased in PA and GA groups compared to WSE, as were along with free amino acid levels. The GA extract activated CaSR with higher potency and efficacy than PA and WSE suggesting the generation of potent kokumi tastants. The in vitro receptor assay might be an expedient tool for screening kokumi tastants prior to conducting human sensory analysis. Collectively, our findings indicate that the meat crust can be a valuable source to generate kokumi tastants via a two-step enzymatic reaction.

The Effect of Elevated Protein Intake on DNA Damage in Older People: Comparative Secondary Analysis of Two Randomized Controlled Trials.

A high protein intake at old age is important for muscle protein synthesis, however, this could also trigger protein oxidation with the potential risk for DNA damage. The aim of this study was to investigate whether an increased protein intake at recommended level or well above would affect DNA damage or change levels of reduced (GSH) and oxidised glutathione (GSSG) in community-dwelling elderly subjects. These analyses were performed in two randomized intervention studies, in Austria and in New Zealand. In both randomized control trials, the mean protein intake was increased with whole foods, in the New Zealand study (n = 29 males, 74.2 ± 3.6 years) to 1.7 g/kg body weight/d (10 weeks intervention; p < 0.001)) in the Austrian study (n = 119 males and females, 72.9 ± 4.8 years) to 1.54 g/kg body weight/d (6 weeks intervention; p < 0.001)). In both studies, single and double strand breaks and as formamidopyrimidine-DNA glycosylase-sensitive sites were investigated in peripheral blood mononuclear cells or whole blood. Further, resistance to H2O2 induced DNA damage, GSH, GSSG and CRP were measured. Increased dietary protein intake did not impact on DNA damage markers and GSH/GSSG levels. A seasonal-based time effect (p < 0.05), which led to a decrease in DNA damage and GSH was observed in the Austrian study. Therefore, increasing the protein intake to more than 20% of the total energy intake in community-dwelling seniors in Austria and New Zealand did not increase measures of DNA damage, change glutathione status or elevate plasma CRP.

Responsiveness of one-carbon metabolites to a high-protein diet in older men: Results from a 10-wk randomized controlled trial.

OBJECTIVES: Dietary strategies to promote successful aging are divergent. Higher-protein diets are recommended to preserve skeletal muscle mass and physical function. Conversely, increased B-vitamin intake, supporting one-carbon (1C) metabolism, reduces the risk of cognitive decline and cardiovascular disease. On the hypothesis that higher protein intake through animal-based sources will benefit 1C regulation by the supply of B vitamins (folate, riboflavin, and vitamins B6 and B12) and methyl donors (choline) despite higher methionine intake, this study explored the effect of a higher-protein diet on 1C metabolite status in older men compared to current protein recommendations. METHODS: Older men (age, 74 ± 3 y) were randomized to receive a diet for 10 wk containing either the recommended dietary allowance (RDA) of protein (0.8 g/kg body weight/d, n = 14), or double that amount (2RDA, n = 15), with differences in protein accounted for by modifying carbohydrate intake. Intervention diets were matched to each individual's energy requirements based on the Harris-Benedict equation and adjusted fortnightly as required depending on physical activity and satiety. Fasting plasma 1C metabolite concentrations were quantified by liquid chromatography coupled with mass spectrometry at baseline and after 10 wk of intervention. RESULTS: Plasma homocysteine concentrations were reduced from baseline to follow-up with both diets. Changes in metabolite ratios reflective of betaine-dependent homocysteine remethylation were specific to the RDA diet, with an increase in the betaine-to-choline ratio and a decrease in the dimethylglycine-to-betaine ratio. Comparatively, increasing folate intake was positively associated with a change in choline concentration and inversely with the betaine-to-choline ratio for the 2RDA group. CONCLUSIONS: Adding to the known benefits of higher protein intake in older people, this study supports a reduction of homocysteine with increased consumption of animal-based protein, although the health effects of differential response of choline metabolites to a higher-protein diet remain uncertain.

The effects of blanching on composition and modification of proteins in navy beans (Phaseolus vulgaris).

Blanching is an important process in the preparation of navy beans (Phaseolus vulgaris L.) for canning. We here explore the effect of blanching which can profoundly affect protein composition and introduce protein-primary-level modifications. Amino acid analysis showed significantly decreased protein abundance (58.5%) in blanched beans compared to raw beans. Proteomic analyses revealed a decrease in high molecular weight isoforms of the major storage globulin proteins phaseolin (mean fold-change -3.7) and legumin (mean fold-change -2.5) and concomitant increase in their low molecular weight isoforms (mean fold-change 6.4 and 8.3, respectively). Blanched beans also had decreased abundance of lipoxygenase (mean fold-change -13.1), an enzyme responsible for product spoilage during storage. Increased lysinoalanine (up to 47%) and highly modified protein fragments were found in the processing waters, indicating heat- induced modifications. Correlating these molecular level changes thus provides a basis for evaluating how processing parameters can be modified to increase protein food quality.

Quality, nutrient and sensory characteristics of aged meat from lambs supplemented with selenomethionine.

Selenium (Se) as a co-factor of antioxidant enzymes is metabolically essential for animals. Its presence in muscle can improve the oxidative stability of meat and is a desirable nutrient for consumers. A novel approach to Se supplementation for meat-producing livestock was demonstrated in a 95-day study of young lambs. DL-selenomethionine (SeMet) was administered by subcutaneous injection at day 0 (3-4 weeks of age) and again at day 54. A Control group (n = 9) received carrier only, whilst Medium and High groups (n = 10) received graded levels of Se. Physicochemical attributes of meat quality and sensory characteristics were measured at 1, 3, 14 and 42 days of ageing (vacuum packaged at -1.5 °C), followed by instrumental colour measurements after 7 days of simulated retail display. There were no significant interactions between SeMet treatment and ageing. Muscle pH, drip and cooking losses, initial display colour and sensory evaluations by trained and consumer panels were unaffected by treatment. Smaller changes in colour during display were observed for the Medium group compared to Control (P < 0.05). The shorter range of ageing times improved meat tenderness however extended ageing decreased colour stability. SeMet markedly increased Se concentrations in muscle, blood, kidney and liver (P < 0.05), resulting in Se enriched meat without appreciable changes in meat quality.

Comparable Postprandial Amino Acid and Gastrointestinal Hormone Responses to Beef Steak Cooked Using Different Methods: A Randomised Crossover Trial.

Cooking changes the texture and tenderness of red meat, which may influence its digestibility, circulatory amino acids (AA) and gastrointestinal (GI) hormonal responses in consumers. In a randomised crossover intervention, healthy males (n = 12) consumed a beef steak sandwich, in which the beef was cooked by either a pan-fried (PF) or sous-vide (SV) method. Plasma AA were measured by ultrahigh performance liquid chromatography (UPLC), while plasma GI hormones were measured using a flow cytometric multiplex array. Following meat ingestion, the circulatory concentrations of some of the essential AA (all the branched-chain AA: leucine, isoleucine and valine; and threonine), some of the nonessential AA (glycine, alanine, tyrosine and proline) and some of the nonproteogenic AA (taurine, citrulline and ornithine) were increased from fasting levels by 120 or 180 min (p < 0.05). There were no differences in circulating AA concentrations between cooking methods. Likewise, of the measured GI hormones, glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1) concentrations increased from fasting levels after consumption of the steak sandwich (p < 0.05), with no differences between the cooking methods. In the healthy male adults, protein digestion and circulating GI hormone responses to a beef-steak breakfast were unaltered by the different cooking methods.

Analysis of Human Faecal Host Proteins: Responsiveness to 10-Week Dietary Intervention Modifying Dietary Protein Intake in Elderly Males.

Faecal proteomics targeting biomarkers of immunity and inflammation have demonstrated clinical application for the identification of changes in gastrointestinal function. However, there are limited comprehensive analyses of the host faecal proteome and how it may be influenced by dietary factors. To examine this, the Homo sapiens post-diet proteome of older males was analysed at the completion of a 10-week dietary intervention, either meeting the minimum dietary protein recommendations (RDA; n = 9) or twice the recommended dietary allowance (2RDA, n = 10). The host faecal proteome differed markedly between individuals, with only a small subset of proteins present in ≥ 60% of subjects (14 and 44 proteins, RDA and 2RDA, respectively, with only 7 common to both groups). No differences were observed between the diet groups on the profiles of host faecal proteins. Faecal proteins were detected from a wide range of protein classes, with high inter-individual variation and absence of obvious impact in response to diets with markedly different protein intake. This suggests that well-matched whole food diets with two-fold variation in protein intake maintained for 10 weeks have minimal impact on human faecal host proteins.

Impact of a High Protein Intake on the Plasma Metabolome in Elderly Males: 10 Week Randomized Dietary Intervention.

High protein diets may improve the maintenance of skeletal muscle mass in the elderly, although it remains less clear what broader impact such diets have on whole body metabolic regulation in the elderly. Non-targeted polar metabolomics analysis using HILIC HPLC-MS was used to profile the circulating plasma metabolome of elderly men (n = 31; 74.7 ± 4.0 years) who were randomized to consume for 10 weeks a diet designed to achieve either protein (RDA; 0.8·g-1·kg-1) or that doubled this recommend intake (2RDA; 1.6.g.kg-1). A limited number of plasma metabolites (n = 24) were significantly differentially regulated by the diet. These included markers of protein anabolism, which increased by the 2RDA diet, including; urea, creatine, and glutarylcarnitine. Whilst in response to the RDA diet; glutamine, glutamic acid, and proline were increased, relative to the 2RDA diet (p < 0.05). Metaboanalyst identified six major metabolic pathways to be influenced by the quantity of protein intake, most notably the arginine and proline pathways. Doubling of the recommended protein intake in older males over 10 weeks exerted only a limited impact on circulating metabolites, as determined by LC-MS. This metabolomic response was almost entirely due to increased circulating abundances of metabolites potentially indicative of altered protein anabolism, without evidence of impact on pathways for metabolic health. Trial Registration: This trial was registered on 3rd March 2016 at the Australia New Zealand Clinical Trial Registry (www.anzctr.org.au) at ACTRN 12616000310460.

Protein Intake at Twice the RDA in Older Men Increases Circulatory Concentrations of the Microbiome Metabolite Trimethylamine-N-Oxide (TMAO).

Higher dietary protein intake is increasingly recommended for the elderly; however, high protein diets have also been linked to increased cardiovascular disease (CVD) risk. Trimethylamine-N-oxide (TMAO) is a bacterial metabolite derived from choline and carnitine abundant from animal protein-rich foods. TMAO may be a novel biomarker for heightened CVD risk. The purpose of this study was to assess the impact of a high protein diet on TMAO. Healthy men (74.2 ± 3.6 years, n = 29) were randomised to consume the recommended dietary allowance of protein (RDA: 0.8 g protein/kg bodyweight/day) or twice the RDA (2RDA) as part of a supplied diet for 10 weeks. Fasting blood samples were collected pre- and post-intervention for measurement of TMAO, blood lipids, glucose tolerance, insulin sensitivity, and inflammatory biomarkers. An oral glucose tolerance test was also performed. In comparison with RDA, the 2RDA diet increased circulatory TMAO (p = 0.002) but unexpectedly decreased renal excretion of TMAO (p = 0.003). LDL cholesterol was increased in 2RDA compared to RDA (p = 0.049), but no differences in other biomarkers of CVD risk and insulin sensitivity were evident between groups. In conclusion, circulatory TMAO is responsive to changes in dietary protein intake in older healthy males.

Comprehensive Profiling of the Circulatory miRNAome Response to a High Protein Diet in Elderly Men: A Potential Role in Inflammatory Response Modulation.

SCOPE: MicroRNA are critical to the coordinated post-transcriptional regulation of gene expression, yet few studies have addressed the influence of habitual diet on microRNA expression. High protein diets impact cardiometabolic health and body composition in the elderly suggesting the possibility of a complex systems response. Therefore, high-throughput small RNA sequencing technology is applied in response to doubling the protein recommended dietary allowance (RDA) over 10 weeks in older men to examine alterations in circulating miRNAome. METHODS AND RESULTS: Older men (n = 31; 74.1 ± 0.6 y) are randomized to consume either RDA (0.8 g kg-1  day-1 ) or 2RDA (1.6 g kg-1  day-1 ) of protein for 10 weeks. Downregulation of five microRNAs (miR-125b-5p, -100-5p, -99a-5p, -23b-3p, and -203a) is observed following 2RDA with no changes in the RDA. In silico functional analysis highlights target gene enrichment in inflammation-related pathways. qPCR quantification of predicted inflammatory genes (TNFα, IL-8, IL-6, pTEN, PPP1CB, and HOXA1) in peripheral blood mononuclear cells shows increased expression following 2RDA diet (p ≤ 0.05). CONCLUSION: The study findings suggest a possible selective alteration in the post-transcriptional regulation of the immune system following a high protein diet. However, very few microRNAs are altered despite a large change in the dietary protein.

Global Provisioning of Red Meat for Flexitarian Diets.

Although not always labeled as such, flexitarianism is the default lifestyle for much of the world, whereby meals based on plant materials provide the bulk of people's calories. The rich nutrition of meat and animal products is often the lynchpin of these diets, even when only consumed occasionally. It provides forms and concentrations of essential proteins, lipids, and micronutrients that are otherwise scarce. However, the production of this meat is resource intensive. It requires large quantities of arable land and water, and typically has lower conversion efficiency of farm inputs to edible outputs compared with crops, poultry, aquaculture, dairy, and eggs. An additional complication is that the quantity of ancillary products produced during slaughterhouse operations is large and underutilized. Each year, approximately 190 million metric tons (MMT) of red meat, including pork, lamb, sheep, veal, beef, and goats are produced globally, half of which will be consumed by less than 25% of the population living in developed countries. With demand for meat expected to exceed 376 MMT by 2030, an increase in the adoption of plant-based diets presents an opportunity for the world to re-evaluate how meat can be sustainably produced, with greater emphasis on animal welfare, nutritional value, product safety, better utilization, and distribution channels. In this article we consider the role meat plays in the modern diet, its production and consumption, opportunities to improve utilization of the animal, the benefits of incorporating a diverse range of red meat into diets, and the strategies that the meat industry should consider in response to flexitarianism.

The effects of a wool hydrolysate on short-chain fatty acid production and fecal microbial composition in the domestic cat (Felis catus).

Novel animal-derived fibers are of interest for the pet food industry. We here introduce a method for extracting wool proteins using controlled hydrolysis of wool. This results in an appropriate form and we demonstrate its application in pet food using the domestic cat. The effect of the wool hydrolysate on biomarkers of digestive health (e.g., fecal short-chain fatty acids and fecal microbial composition, apparent amino acid (AA) and protein digestibility), are also described. In a feeding study, a cohort of cats (n = 8 per treatment) were fed a basal diet (Control), or the basal diet supplemented with 2% wool hydrolysate, 2% inulin (Synergy1; as is) or 2% cellulose (Novagel; as is). The concentration of butyric acid was not significant (P = 0.102) between treatment groups. The concentration of fecal lactic acid was greatest (P = 0.007) in cats on the Novagel diet. Valeric acid was increased (P = 0.001) in cats fed Synergy1. Supplementation of cat diet with a wool hydrolysate showed similarities to Novagel supplementation in terms of its effects on fecal short-chain fatty acid concentrations and fecal microbiota composition. Wool hydrolysate increased apparent cysteine digestibility compared to Synergy 1 or Novogel. In terms of fecal health, intake, and palatability, the diet supplemented with wool hydrolysate was not detrimental, being similar to currently used dietary fiber supplements. These findings indicate that wool hydrolysates offer promise as an animal-derived supplement source for pet diets.

Novel meat-enriched foods for older consumers.

Red meat enriched versions of bread, spaghetti, yoghurt, ice cream and chocolate were prototyped and assessed for some of their physical, chemical and microbiological properties, as well as sensory appeal. The protein content of the products were significantly increased and their colour went darker with meat enrichment (p<0.05). Bread volume and spaghetti tensile strength increased and ice cream meltability and yoghurt apparent viscosity decreased with meat enrichment (p<0.05). The overall acceptability/liking of bread, flavoured ice cream and spaghetti were not affected (p>0.05) but that of non-flavoured ice cream and yoghurt went down (p<0.05) with meat enrichment. 75% of the 940 panellist who ate the meat-enriched chocolates either loved or slightly-liked them. The outcome of the present study would assist in making the nutrition of meat available in a wider range of product categories, helping the meat industry stretch its established business models, and encouraging further development of novel food choices for elderly and other groups of consumers.

The effects of dietary protein intake on appendicular lean mass and muscle function in elderly men: a 10-wk randomized controlled trial.

Background: The Recommended Daily Allowance (RDA) for protein intake in the adult population is widely promoted as 0.8 g · kg-1 · d-1 Aging may increase protein requirements, particularly to maintain muscle mass.Objective: We investigated whether controlled protein consumption at the current RDA or twice the RDA (2RDA) affects skeletal muscle mass and physical function in elderly men.Design: In this parallel-group randomized trial, 29 men aged >70 y [mean ± SD body mass index (in kg/m2): 28.3 ± 4.2] were provided with a complete diet containing either 0.8 (RDA) or 1.6 (2RDA) g protein · kg-1 · d-1, aimed to balance energy needs. Before treatment and after 10 wk of intervention, whole-body and appendicular lean mass were measured by using dual-energy X-ray absorptiometry. Knee-extension peak power was measured with dynamometry.Results: Both groups were found to have been in a moderate negative energy balance (mean ± SD RDA: 209 ± 213 kcal/d; 2RDA 145 ± 214 kcal/d; P= 0.427 for difference between the groups). In comparison with RDA, whole-body lean mass increased in 2RDA (P = 0.001; 1.49 ± 1.30 kg, P < 0.001 compared with -0.55 ± 1.49 kg, P = 0.149). This difference was mostly accounted for by an increase in trunk lean mass found in 2RDA (+1.39 ± 1.09 kg, P < 0.001). Appendicular lean mass also decreased in RDA compared with 2RDA (P = 0.022), driven by a reduction in RDA (-0.64 ± 0.91 kg, P = 0.005 compared with 0.11 ± 0.57 kg, P = 0.592). Adjusting for energy imbalances did not alter these findings. Knee-extension peak power was also differently affected (P = 0.012; 26.6 ± 47.7 W, P = 0.015 in 2RDA compared with -11.7 ± 31.0 W, P = 0.180 in RDA).Conclusions: Consumption of a diet providing 2RDA for protein compared with the current guidelines was found to have beneficial effects on lean body mass and leg power in elderly men. These effects were not explained by differences in energy balance. This trial was registered at the Australia New Zealand Clinical Trial Registry (www.anzctr.org.au) as ACTRN12616000310460.

Selenomethionine as a Safer Substitute for Barium Selenate in Long-Acting Injectable Se Supplements for Food-Producing Animals.

Nutritional supplementation with selenium (Se) can prevent Se deficiency in food-producing animals. Injection with slow-release formulations is a preferred method for free-range grazing sheep and cattle, and barium selenate (BaSeO4) provides optimal efficacy. This chemical can become a health risk to humans if the concentrated depot of an injection site is consumed, and consequently such use is recently banned in the EU. A possible replacement is selenomethionine (SeMet), a naturally occurring form of Se supplementation hitherto only administered orally. In four animal studies we found that injection with SeMet maintained nutritionally adequate concentrations of Se in blood and tissues of lambs for at least 191 days and in blood and milk of dairy cows for at least 95 days. Stereoisomer forms L- and DL-SeMet were functionally equivalent. This is the first demonstration that injectable SeMet can deliver efficacy similar to BaSeO4 but with less risk of undesirable residues in edible tissues.

Physicochemical and sensory characterization of gnocchi and the effects of novel formulation on in vitro digestibility.

Conventional gnocchi are small Italian dumplings made from potatoes, flour, and eggs. In this study, a range of gnocchi-type products containing navy bean and beef meat (10-40% w/w) were developed. The nutritional, physicochemical and sensory properties of the formulated gnocchi were determined, and a Modified in vitro Stomach Stir Tank (MISST) system was used to determine in vitro digestibility. Adding meat significantly increased the fat and protein content of cooked gnocchi type products compared to the control sample. Addition of navy bean and meat also significantly increased hardness, springiness, and chewiness, of most gnocchi type products compared to control sample. In vitro studies showed that pH increased faster in samples high in meat and navy bean content during the initial 30 min to control. The addition of high levels of meat emulsion and navy bean increased, springiness, beany, and meaty flavour. Gnocchi with 20% meat emulsion was similar to control upto some extent being characterized to have flocculent, soft, chewy, and wheaty in flavour. The addition of meat and navy bean did not affect the digestibility of starch in the gastrointestinal tract. Fortified gnocchi with meat and bean was showed a promising vehicle to deliver nutritive values without any changes in starch digestibility.

Effects of meat addition on pasta structure, nutrition and in vitro digestibility.

In our study, semolina flour was substituted with beef emulsion (EM) at three different levels of 15, 30 and 45% (w/w) to develop a pasta with enhanced nutritional profile. The protein, fat, and water content significantly increased with addition of meat. The addition of meat enhanced the pasta gluten network. The redness and yellowness of cooked pasta increased with meat addition. Tensile strength increased from 0.018N/mm(2) in the control sample to 0.046N/mm(2) in 45% beef emulsion (45EM) sample. All meat-containing samples had significantly higher elasticity than control (0.039N/mm(2)). GI significantly decreased and IVPD value increased in 45EM sample. Five essential amino acids (leucine, lysine, methionine, threonine, tryptophan) in pasta digesta increased significantly with increasing meat addition.

The in vitro digestibility of beef varies with its inherent ultimate pH.

Animal carcasses and cuts of meat are usually differentiated and valued according to size and compositional attributes. An underappreciated variable of red meat is its inherent ultimate pH (pHu) value, which affects organoleptic and processing characteristics. This study tests the hypothesis that high pHu aged meat would be more digestible than low pHu unaged (fresh) meat. Longissimus dorsi muscles collected from 59 bull carcasses had pHu values of 5.6-6.9. These were aged for 21 days at -1.5 °C, then raw and cooked (72 °C) samples were enzymatically digested at 37 °C with pepsin (pH 1.9 for 90 min) followed by pancreatin (pH 8.0 for an additional 120 min) to simulate conditions in the stomach and small intestine, respectively. Meat proteins and peptides in the digests were separated by 1D SDS PAGE. Regardless of pHu, ageing or cooking, most sarcoplasmic and myofibrillar proteins were rapidly digested by pepsin, with concomitant release of products identified by LC-MS/MS as mainly myosin-1, -2 and -7, α-actinin-2 or -3 and tropomyosin beta and alpha chains. These products were resistant to further digestion for the entire 210 min duration of the incubation. In terms of rate and extent of digestibility of these resistant products, high pHu > low pHu (P < 0.001), whereas aged > unaged (P < 0.003), with the effect of cooking dependent on pHu and varying somewhat by protein. Overall, the digestibility of meat samples increased with increasing pHu (P < 0.001). Beef meat was highly digestible but could be further differentiated on the basis of its pHu and the ease of digestibility of proteins. Specific carcasses or cuts could be targeted to consumer groups in order to provide benefits and add value.

Trace element supplementation of livestock in new zealand: meeting the challenges of free-range grazing systems.

Managing the mineral nutrition of free-range grazing livestock can be challenging. On farms where grazing animals are infrequently yarded, there are limited opportunities to administer trace element supplements via feeds and concentrates. In New Zealand, where the majority of sheep, cattle, and deer graze pasture year round, inadequate intake of cobalt, copper, iodine and selenium is prevalent. Scientists and farmers have developed efficient strategies to monitor and treat these dietary deficiencies. Supplementation methods suited to grazing livestock include long-acting injections, slow-release intraruminal boluses, trace element-amended fertilisers, and reticulated water supplies on dairy farms.