Haplotypes for Type, Degree, and Rate of Marbling in Cattle Are Syntenic with Human Muscular Dystrophy

Intramuscular adipogenesis in cattle: Effects of body fat distribution and macrophage infiltration

Ectopic fat is defined by the deposition of adipose tissue within non-adipose tissue such as skeletal muscle. Japanese Black cattle (Wagyu) are characterized by the ability to accumulate high amounts of intramuscular adipose tissue. Obese conditions enhance the accumulation of ectopic fat. This review shows the effects of subcutaneous and visceral fat distribution on Wagyu intramuscular adipogenesis. Obese conditions also stimulate the macrophage infiltration into adipose tissues. Adipose tissue macrophages have reported to regulate adipose tissue growth and ectopic fat accumulation in humans and rodents. Wagyu is characterized by the higher capacity for intramuscular adipogenesis than Holsteins. This review discusses the depot-specific effects of macrophage infiltration among subcutaneous, visceral, and intramuscular adipose tissue on intramuscular adipogenesis in Wagyu and Holstein cattle. Recently, metabolome analysis has been used to identify obesity-related biomarkers by comparing the biological samples between lean and obese patients. This review introduces the metabolomic profiles of plasma and intramuscular adipose tissue between Wagyu and Holsteins.

Metabolomic analysis of plasma and intramuscular adipose tissue between Wagyu and Holstein cattle

In this experiment, we studied the effects of breed differences in intramuscular adipogenic capacity on the metabolomic profiles of plasma and intramuscular adipose tissue between Wagyu (high intramuscular adipogenic capacity) and Holstein (low intramuscular adipogenic capacity) using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). We showed that the intramuscular fat content, intramuscular adipocyte size and the expression of adipogenic transcription factors (C/EBPβ and C/EBPα) of Wagyu were significantly higher than those of Holstein. Metabolites detected at significantly higher levels in Wagyu plasma were related to the tricarboxylic acid cycle, lipid synthesis, fatty acid metabolism, diabetes, and glucose homeostasis. In contrast, metabolites detected at significantly higher levels in Holstein plasma were related to choline metabolism, the ethanolamine pathway, glutathione homeostasis, nucleic acid metabolism, and amino acid metabolism. Metabolites detected at significantly higher levels in Holstein intramuscular adipose tissue were related to nucleic acid metabolism, amino acid metabolism, amino sugar metabolism, beta oxidation, and the ethanolamine pathway. There were no metabolites significantly higher levels in Wagyu intramuscular adipose tissue. These results indicate candidate biomarkers of breed differences in intramuscular adipogenic capacity between Wagyu and Holstein.

Impact of merging commercial breeding lines on the genetic diversity of Landrace pigs

BACKGROUND

The pig breeding industry has undergone a large number of mergers in the past decades. Various commercial lines were merged or discontinued, which is expected to reduce the genetic diversity of the pig species. The objective of the current study was to investigate the genetic diversity of different former Dutch Landrace breeding lines and quantify their relationship with the current Dutch Landrace breed that originated from these lines.

RESULTS

Principal component analysis clearly divided the former Landrace lines into two main clusters, which are represented by Norwegian/Finnish Landrace lines and Dutch Landrace lines. Structure analysis revealed that each of the lines that are present in the Dutch Gene bank has a unique genetic identity. The current Dutch Landrace breed shows a high level of admixture and is closely related to the six former lines. The Dumeco N-line, which is conserved in the Dutch Gene bank, is poorly represented in the current Dutch Landrace. All seven lines (the six former and the current line) contribute almost equally to the genetic diversity of the Dutch Landrace breed. As expected, the current Dutch Landrace breed comprises only a small proportion of unique genetic diversity that was not present in the other lines. The genetic diversity level, as measured by Eding's core set method, was equal to 0.89 for the current Dutch Landrace breed, whereas total genetic diversity across the seven lines, measured by the same method, was equal to 0.99.

CONCLUSIONS

The current Dutch Landrace breed shows a high level of admixture and is closely related to the six former Dutch Landrace lines. Merging of commercial Landrace lines has reduced the genetic diversity of the Landrace population in the Netherlands, although a large proportion of the original variation is maintained. Thus, our recommendation is to conserve breeding lines in a gene bank before they are merged.

Genetics of Marbling in Wagyu Revealed by the Melting Temperature of Intramuscular and Subcutaneous Lipids

Extreme marbling or intramuscular deposition of lipid is associated with Wagyu breeds and is therefore assumed to be largely inherited. However, even within 100% full blood Wagyu prepared under standard conditions, there is unpredictable scatter of the degree of marbling. Here, we evaluate melting temperature (T_m) of intramuscular fat as an alternative to visual scores of marbling. We show that “long fed” Wagyu generally has T_m below body temperature but with a considerable range under standardized conditions. Individual sires have a major impact indicating that the variation is genetic rather than environmental or random error. In order to measure differences of lower marbling breeds and at shorter feeding periods, we have compared T_m in subcutaneous fat samples from over the striploin. Supplementary feeding for 100 to 150 days leads to a rapid decrease in T_m of 50% Red Wagyu (Akaushi) : 50% European crosses, when compared to 100% European. This improvement indicates that the genetic effect of Wagyu is useful, predictable, and highly penetrant. Contemporaneous DNA extraction does not affect the measurement of T_m. Thus, provenance can be traced and substitution can be eliminated in a simple and cost-effective manner.