The objective of this study was to investigate meat quality of Xiangxi yellow cattle of different ages in comparison to Aberdeen Angus. At the ages of 6, 18, and 30 months, 10 female animals for both Xiangxi yellow cattle and Aberdeen Angus cattle were randomly selected and slaughtered. The proximate composition analysis, fatty acid profiles and flavor compounds were measured on the longissimus thoracis (LT) muscle samples. One boneless loin chop was dissected and used for sensory evaluation by a 10-persoon trained taste panel. The data obtained showed that Xiangxi yellow cattle deposited similarly high level of intramuscular fat as Angus at the age of 18 month and the polyunsaturated fatty acid in muscle along with the PUFA/SFA ratio reached the highest levels at this age. Inosine 5′-monophosphate (IMP) was the predominant umami compound in beef, which concentration was significantly higher (p < 0.05) at month 18, but not different between Angus and Xiangxi yellow cattle. Multiple volatile flavor compounds were higher (p < 0.05) in concentrations in meat from Xiangxi yellow cattle at ages of 18 and 30 months when compared to Angus. Sensory analysis revealed that Xiangxi yellow cattle (18 and 30 months) and Angus (30 months) were superior in meat overall eating quality to Xiangxi yellow cattle (6 months) and Angus (6 and 18 months). This study showed that Xiangxi yellow cattle are a fine cattle breed with equal or even better meat quality attributes when compared to Angus. It is proper to slaughter Xiangxi yellow cattle at the age of 18 months for high quality beef production.

Background: To improve the grade of beef marbling has great economic value in the cattle industry since marbling has the traits of high quality and comprehensive nutrition. And because of the marbling’s importance and complexity, it is indispensable to explore marbled beef at multiple levels. This experiment studied the relationship between fecal metabolites and marbling characters, and further screened biomarkers. Results: We performed fecal metabolomics analysis on 30 individuals selected from 100 crossbreed cattle (Luxi Yellow cattle ♀ × Japanese Wagyu cattle ♂), 15 with an extremely high-grade marbling beef and 15 with an extremely low-grade marbling beef. A total of 9959 and 8389 m/z features were detected in positive ionization and negative ionization mode by liquid chromatography-mass spectrometry (LC-MS). Unfortunately, the sample separation in the PCA is not obvious, and the predictive ability of the orthogonal partial least squares discrimination analysis (OPLS-DA) model is not good. However, we got six differential metabolites filtered by VIP > 1 and p < 0.05. After that, we used weighted correlation network analysis (WGCNA) and found out a module in each positive and negative mode most related to the trait of marbling beef, and then identified three metabolites in positive mode. By further annotation of the Kyoto encyclopedia of genes and genomes (KEGG), it was found that these metabolites involved a variety of metabolic ways, including sphingomyelin metabolism, linoleic acid metabolism, glycerophospholipid metabolism, and so on. Finally, receiver operating characteristic (ROC) analysis was used to evaluate the predictability of metabolites, and the result showed that SM(d18:0/16:1(9Z)) (AUC = 0.72), PC(15:0/18:2(9Z,12Z)) (AUC = 0.72), ADP (AUC = 0.71), PC(16:0/16:0) (AUC = 0.73), and 3-O-Sulfogalactosylceramide (d18:1/18:0) (AUC = 0.69) have an accuracy diagnosis. Conclusions: In conclusion, this study supports new opinions for the successive evaluation of marbling beef through metabolites. Furthermore, six non-invasive fecal metabolites that can evaluate beef marbling grade were found, including SM(d18:0/16:1(9Z)), PC(15:0/18:2(9Z,12Z)), ADP, PC(16:0/16:0), and 3-O-Sulfogalactosylceramide.

This study investigated the dietary supplementation of starches with different carbohydrate sources on the proximate composition, meat quality, flavor substances, and volatile flavor substances in the meat of Chinese Xiangxi yellow cattle. A total of 21 Chinese Xiangxi yellow steers (20 ± 0.5 months, 310 kg ± 5.85 kg) were randomly divided into three groups (control, corn, and barley groups), with seven steers per group. The control steers received a conventional diet (coarse forage type: whole silage corn at the end of the dough stage as the main source), the corn group received a diet with corn as the main carbohydrate source, and the barley group received a diet with barley as the main carbohydrate source. The experiment lasted for 300 d. and the means of the final weights in the control, corn, and barley groups were 290 kg, 359 kg, and 345 kg. The diets were isonitrogenous. The corn and barley groups reduced the moisture (p = 0.04) and improved the intramuscular fat content of the meat (p = 0.002). They also improved meat color (a*) (p = 0.01) and reduced cooking loss (p = 0.08), shear force (p = 0.002), and water loss (p = 0.001). There was no significant difference in the 5′-nucleotide content (p > 0.05), the equivalent umami concentration (EUC) (p = 0.88), and taste activity value (TAV) (p > 0.05) among the three groups. The 5′-IMP (umami) content was the highest in the 5′-nucleotide and its TAV > 1. The corn and barley groups improved the content of tasty amino acids (tAA, p < 0.001). The corn group had a higher content of sweet amino acids (SAA, p < 0.001) and total amino acids (TAA, p = 0.003). Corn and barley improved the levels of MUFA (p < 0.001), PUFA (p = 0.002), n-3 PUFA (p = 0.005), and n-6 PUFA (p = 0.020). The levels of alcohols, hydrocarbons, and aldehydes in the corn group were higher than in the barley and control groups (p < 0.001). The esters content in the corn group was higher than in the barley and control groups (p = 0.050). In conclusion, feeding corn or barley as a carbohydrate source can improve the nutrient content and taste. Feeding corn as a carbohydrate source can improve the content of free amino acids (Cys, Glu, Gly, Thr, Leu, Trp, Gln, Asn, and Asp), fatty acids (saturated fatty acid, monounsaturated fatty acid, polyunsaturated fatty acid, n-3PUFA, n-6PUFA, and total fatty acid), and volatile flavor substances (alcohols, aldehydes, acids, and hydrocarbons) to improve the flavor and meat quality.

High-concentrate feeding during late fattening can impair metabolic health and meat quality in beef cattle, yet effective nutritional strategies remain limited. Choline and nicotinic acid are involved in lipid and energy metabolism, but information on their combined or sequential supplementation is scarce. This study evaluated rumen-protected choline given alone or together with nicotinic acid on growth performance, meat quality, serum biochemical indices, serum metabolomics, and free amino acid profiles in late-fattening beef cattle. Twenty-four black cattle were randomly allocated to three groups: CON (basal diet), CC (basal diet + 10 g/d RPC for 90 d), and CC-CNA (basal diet + 10 g/d RPC for 90 d + 10 g/d protected NA during the final 30 d). Shear force was significantly lower in both CC and CC-CNA than in CON (p < 0.05), indicating improved tenderness. Exploratory serum metabolomics identified treatment-associated metabolites and pathways related to amino acid, purine, sphingolipid, and lipid metabolism. Taste-related free amino acids were also altered by supplementation (p < 0.05). RPC alone or with short-term NA may improve tenderness and modulate systemic metabolic responses; larger studies with direct sensory evaluation are needed to confirm growth and flavor-related effects.

The objective of study was to evaluate the effects of energy level in starter ration on blood biochemical parameters, hormone profile, immune response and antioxidant status of calves. A total of eighteen angus calves were divided into three groups in such a way that each group had six calves. Three energy levels were {9 MJ/kg, low metabolizable energy (LME), 12.38 MJ/kg, medium metabolizable energy (MME) and 13.62 MJ/kg, high metabolizable energy (HME)}fed to experimental groups. Results showed that hemoglobin, red blood cells, hematocrit, thrombocytocrit and high-density lipoprotein was higher in HME diet (plessthan0.05). While, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean platelet volume and platelet distribution width was higher in MME diet as compared to HME diet plesstha0.05). Results of immunity revealed that IgA content were lowest in calves fed LME diet plesstha0.05). Calves received different energy level in the diet had no effect on IgG, IgM and C4 (P>0.05). However, the calves on LME starter diet represented higher blood complement C3 contents plesstha0.05). It is concluded that blood metabolites were influenced by energy level in Angus calves.