Algesia and local responses induced by neurokinin A and substance P in human skin and temporal muscle

Neurokinin A (NKA), substance P (SP) and the two peptides combined (SP + NKA) were injected intracutaneously on the forearm and into the temporal muscle of healthy volunteers. Pain intensity, cutaneous wheal and flare responses and tenderness of the temporal muscle were quantitated. SP but not NKA induced cutaneous pain. This relates the algesic effect of SP to the specific N-terminal amino acid sequence of the peptide, not shared by NKA. NKA, however, potentiated the algesic effect of SP as SP + NKA induced a significantly prolonged cutaneous pain sensation. Both peptides induced wheals, but only SP induced flare. These results confirm previous studies relating wheal formation to the identical C-terminal amino acid sequence of the two peptides and flare reaction to the N-terminal part of SP. Injections into the temporal muscle did not cause pain or tenderness.     

Carcass and meat quality traits of chickens fed diets concurrently supplemented with vitamins C and E under constant heat stress

The objective of this study was to determine if a diet supplemented simultaneously with vitamins C and E would alleviate the negative effects of heat stress, applied between 28 and 42 days of age, on performance, carcass and meat quality traits of broiler chickens. A total of 384 male broiler chickens were assigned to a completely randomized design, with a 2×3 factorial arrangement (diet with or without vitamin supplementation and two ambient temperatures plus a pair-feeding group) and 16 replicates. Chickens were kept in thermoneutral conditions up to 28 days of age. They were then housed in groups of four per cage, in three environmentally controlled chambers: two thermoneutral (22.5 and 22.6°C) and one for heat stress (32°C). Half the chickens were fed a diet supplemented with vitamins C (257 to 288 mg/kg) and E (93 to 109 mg/kg). In the thermoneutral chambers, half of the chickens were pair-fed to heat stressed chickens, receiving each day the average feed intake recorded in the heat stress chamber in the previous day. Meat physical quality analyses were performed on the pectoralis major muscle. No ambient temperature×diet supplementation interaction effects were detected on performance, carcass, or meat quality traits. The supplemented diet resulted in lower growth performance, attributed either to a carry-over effect of the lower initial BW, or to a possible catabolic effect of vitamins C and E when supplemented simultaneously at high levels. Heat stress reduced slaughter and carcass weights, average daily gain and feed intake, and increased feed conversion. Growth performance of pair-fed chickens was similar to that of heat stressed chickens. Exposure to heat stress increased carcass and abdominal fat percentages, but reduced breast, liver and heart percentages. Pair-fed chickens showed the lowest fat percentage and their breast percentage was similar to controls. Heat stress increased meat pH and negatively affected meat color and cooking loss. In pair-fed chickens, meat color was similar to the heat stressed group. Shear force was not influenced by heat stress, but pair-fed chickens showed the tenderest meat. In conclusion, reduction in growth performance and negative changes in meat color in heat stressed chickens were attributed to depression in feed intake, whereas negative changes in body composition, higher meat pH and cooking loss were credited to high ambient temperature per se. Diet supplementation with vitamins C and E as antioxidants did not mitigate any of these negative effects.     

Genotypic effects of calpain 1 and calpastatin on the tenderness of cooked M. longissimus dorsi steaks from Jersey x Limousin, Angus and Hereford-cross cattle

Single nucleotide polymorphisms (SNPs) in the calpain 1 (CAPN1) and calpastatin (CAST) genes were studied to determine their effects on meat tenderness in Bos taurus cattle. Strip loins (M. longissimus dorsi) were removed from cattle in four resource populations after slaughter (n = 1042), aged under controlled conditions until fixed times after rigor mortis, cooked and measured using a tenderometer. Animals were genotyped for the CAPN1 SNP c.947C>G (p.Ala316Gly; AF252504) and for the CAST SNP c.2959A>G (AF159246). Frequencies of CAPN1 C alleles ranged from 23% to 68%, and CAST A alleles from 84% to 99.5%. From all data combined, the CAPN1 CC genotype (compared with the GG genotype) was associated with a 20.1 +/- 1.7% reduced average shear force at intermediate stages of ageing (P < 0.001) and with a 9.5 +/- 1.3% reduction near ultimate tenderness (P < 0.001). The heterozygote was intermediate. For CAST, corresponding values for AA compared with AG genotypes were reductions of 8.6 +/- 2.0% and 5.1 +/- 1.6% respectively (both P < 0.001), but there were too few GG genotypes for comparison. There were small interactions between the CAPN1 and CAST genotypes. For the CAPN1 and CAST genotypes combined, the maximal genotype effect in average shear force was 25.7 +/- 5.5% (P < 0.001) at intermediate stages and 15.2 +/- 4.8% near ultimate tenderness (P < 0.01).     

Love me tender: an Omics window on the bovine meat tenderness network

Meat tenderness prediction is a challenging task, especially in Maremmana, an Italian autochtonous and highly appreciated beef breed. In the present study we reported an integrated proteomics, phosphoproteomics and metabolomics overview of meat tenderness in longissimus dorsi from 15 male Maremmana individuals, through the discrimination of tender and tough groups via standard meat tenderness indicators (WBS, MFI(4 h), MFI(10 days), sarcomere length) and their correlation with results from Omics analyses. Results revealed that the tender meat group was characterized by higher levels of glycolytic enzymes, which were less phosphorylated and overall more active (lactate accumulation was higher in the tender group), than in tough counterparts. Additionally, we could observe a higher level of oxidative stress in the tender group. No proteomics nor phosphoproteomics result hinted at the widely accepted role of calpains and cathepsins, except for the indication of calcium homeostasis dysregulation. Nevertheless, myofibrillar degradation was monitored and related to structural protein fragmentations. Fragmentation of structural proteins and activities of glycolytic enzymes were inversely related to their phosphorylation levels, suggesting that PTMs might add further levels of complexity in the frame of meat tenderness.     

The effect of calcium chloride injection on shear force and caspase activities in bovine longissimus muscles during postmortem conditioning

Tenderness is considered as the most important quality determinant of meat. Calcium chloride application has been shown to improve tenderness by regulating endogenous proteinases. This study was designed to determine the effect of 300 mM calcium chloride injection on myofibrillar structures, caspase activities and shear force in longissimus muscles of bulls during postmortem storage of 7 days. Myofibrillar fragmentation index was determined as an index of proteolysis occurring in muscle fibers and associated proteins. Maximum tenderness was observed at days 4 and 7 in both treated and control samples. The injection of calcium chloride significantly increased myofibrillar proteolysis and improved tenderness at postmortem days 4 and 7. The treatment reduced caspase-9 activity at 4 h and day 4, whereas those of caspase-8 and -3 activities at days 1 and 4 with respect to control. The improved tenderness and increased myofibril fragmentation with decreased caspase activities suggested that the proteolytic systems activated with calcium chloride injection possibly behave independent of the caspase system.     

Sensory evaluation and its relationship to physical meat quality attributes of beef from Nguni and Bonsmara steers raised on natural pasture

The current study compared sensory characteristics and their relationships with physical meat characteristics of beef from Nguni and Bonsmara steers. Nguni beef was more (P < 0.05) tender than Bonsmara beef after ageing for 2 and 21 days, and had higher (P < 0.05) intramuscular fat (IMF; 1.12%) than Bonsmara beef (1.07%). Nguni beef had higher (P < 0.05) sensory scores than Bonsmara beef after ageing for 2 days. There were no (P > 0.05) relationships between IMF and sensory characteristics. Aroma intensity, impression on juiciness and tenderness-related scores were affected (P < 0.05) by pH. There were significant (P < 0.05) correlations between most physical meat characteristics and sensory characteristics. Nguni beef had better sensory scores than Bonsmara beef for beef aged for 2 days. While most physical meat characteristics were correlated to sensory scores, all sensory scores were not significantly correlated to IMF.     

Polymorphisms in calpastatin and mu‐calpain genes are associated with beef iron content

The objective of this study was to assess the association of markers in the calpastatin and mu‐calpain loci with iron in beef cattle muscle. The population consisted of 259 cross‐bred steers from Beefmaster, Brangus, Bonsmara, Romosinuano, Hereford and Angus sires. Total iron and heme iron concentrations were measured. Markers in the calpastatin (referred to as CAST) and mu‐calpain (referred to as CAPN4751) genes were used to assess their association with iron levels. The mean and standard error for iron and heme iron content in the population was 35.6 ± 1.3 μg and 27.1 ± 1.4 μg respectively. Significant associations (P < 0.01) of markers were observed for both iron and heme iron content. For CAST, animals with the CC genotype had higher levels of iron and heme iron in longissimus dorsi muscle. For CAPN4751, individuals with the TT genotype had higher concentrations of iron and heme iron than did animals with the CC and CT genotypes. Genotypes known to be associated with tougher meat were associated with higher levels of iron concentration.     

Effect of single nucleotide polymorphisms of CAPN1 and CAST genes on meat traits in Nellore beef cattle (Bos indicus) and in their crosses with Bos taurus

The objectives of this work were to study the segregation of single nucleotide polymorphisms of the calpain 1, large subunit ( CAPN1 ) and calpastatin ( CAST ) genes in Nellore ( Bos indicus ) and Nellore × Bos taurus beef cattle, as well as to evaluate their effects on meat traits. For this, 300 animals, including 114 Nellore, 67 Angus × Nellore, 44 Rubia Gallega × Nellore, 41 Canchim, 19 Brangus three-way crosses and 15 Braunvieh three-way crosses, were genotyped for the CAPN4751 [AF_248054.2:g.6545C>T (GenBank accession AF248054.2 )] and CAST/DdeI [AF_159246.1:g.2959A>G (GenBank accession AF159246.1 )] polymorphisms and phenotyped for Ribeye Area, Backfat Thickness, Intramuscular Fat, Shear Force (SF) and Myofibrillar Fragmentation Index (MFI). In relation to the CAPN4751 polymorphism, a frequency of 10.5% was observed for the C allele in the Nellore breed. In the total sample of studied animals, a significant association was found between genotypes and meat tenderness, assessed by SF ( P  = 0.005) and MFI ( P  = 0.008), with genotype CT being more favourable than TT. For the CAST/DdeI polymorphism, a frequency of 55.7% was found for the A allele in the Nellore breed. In the total sample, a significant association was observed between genotypes and meat tenderness – SF ( P  = 0.004) and MFI ( P  = 0.006), with genotype AA being more favourable than AG. The relationship between genotypes and aged meat tenderness in confluence with the distribution of favourable alleles shows great potential for application of the CAPN4751 and CAST/DdeI polymorphisms in the genetic improvement of the Nellore breed, whilst contributing to the validation, in this breed and in its crosses with B. taurus , of the association results previously described in the literature.     

Effects of ractopamine hydrochloride and dietary protein content on performance,carcass traits and meat quality of Nellore bulls

Ractopamine hydrochloride (RH) alters protein metabolism and improves growth performance in Bos taurus cattle with high carcass fat. Our objective was to evaluate the effects of RH, dietary CP and RH×CP interaction on performance, blood metabolites, carcass characteristics and meat quality of young Nellore bulls. A total of 48 bulls were randomly assigned to four treatments in a 2×2 factorial arrangement. The factors were two levels of dietary CP (100% and 120% of metabolizable protein requirement, defined as CP100 and CP120, respectively), and two levels of RH (0 and 300 mg/animal·per day). Treated animal received RH for the final 35 days before slaughter. Animals were weighed at the beginning of the feedlot period (day 63), at the beginning of ractopamine supplementation (day 0), after 18 days of supplementation (day 18) and before slaughter (day 34). Animals were slaughtered and hot carcass weights recorded. After chilling, carcass data was collected and longissimus samples were obtained for determination of meat quality. The 9–11th rib section was removed for carcass composition analysis. Supplementation with RH increased ADG independently of dietary CP. There was a RH×CP interaction on dry matter intake (DMI), where RH reduced DMI at CP120, with no effect at CP100. Ractopamine improved feed efficiency, without RH×CP interaction. Ractopamine had no effect on plasma creatinine and urea concentration. Greater dietary CP tended to increase blood urea, and there was a RH×CP interaction for plasma total protein. Ractopamine supplementation increased plasma total protein at CP120, and had no effect at CP100. Ractopamine also decreased plasma glucose concentration at CP100, but had no effect at CP120. Ractopamine increased alkaline phosphatase activity at CP120 and had no effect at CP100. There was a tendency for RH to increase longissimus muscle area, independently of dietary CP. Ractopamine did not alter fat thickness; however, fat thickness was reduced by greater CP in the diet. Supplementation with RH decreased meat shear force, but only at day 0 of aging, having no effect after 7, 14 or 21 days. Greater dietary protein increased meat shear force after 0 and 7 days of aging, with no effect after 14 or 21 days. These results demonstrate for the first time the efficacy of ractopamine supplementation to improve gain and feed efficiency of intact Bos indicus males, with relatively low carcass fat content. Ractopamine effects were not further improved by increasing dietary protein content above requirements.