Genomic imprinting variances of beef carcass traits and physiochemical characteristics in Japanese Black cattle

The objective of this study was to estimate variance components related to imprinting for carcass traits and physiochemical characteristics in Japanese Black cattle. The carcass records obtained from 4,220 Japanese Black feedlot cattle included carcass weight (CW), rib eye area (REA), rib thickness, subcutaneous fat thickness, and beef marbling score (BMS), and the physiochemical characteristics were fat, moisture, glycogen per proportion of moisture content, oleic acid, and monounsaturated fatty acids (MUFA). To detect gametic effects, an imprinting model was fitted. High additive heritabilities were estimated for all traits (from 0.516 for glycogen to 0.853 for fat) and were reduced in Mendelian heritability. The range of the differences was from 0.002 (CW) to 0.331 (fat and moisture), and the reductions were due to their imprinting variances. The ratio of the imprinting variance to the total additive genetic variance for REA (0.374), BMS (0.291), fat (0.387), moisture (0.388), and MUFA (0.337) were large (p < 0.05). These imprinting variances were due to the maternal contribution and suggested the existence of maternally expressed genomic imprinting effects on the traits in Japanese Black cattle. Therefore, maternal gametic effects should be considered in breeding programs for Japanese Black cattle.

Changes in taste compounds, breaking properties, and sensory attributes during dry aging of beef from Japanese black cattle

Analysis of the quality of highly marbled beef during dry aging for 60days after slaughter showed that the changes in some qualities differed from those of conventional meat. The tenderness of these meats did not change during aging for 50days but then gradually increased until day 60. The juiciness of these meats, as determined by sensory evaluation, did not change during aging for 60days, except for a decrease on day 20. The umami intensity of these meats in the sensory evaluation and the value calculated by Glu and IMP quantification were highest on day 40. This high umami intensity was induced by the synergistic effect of umami compounds such as Glu and IMP. These results for tenderness, juiciness, umami intensity, and flavor intensity suggested that the best duration of dry aging for highly marbled beef was 40days.

Effect of fat content on sensory characteristics of marbled beef from Japanese Black steers

To analyze the sensory characteristics of meat samples with a crude fat content between 23.8% and 48.6% taken from 34 Japanese Black steers, we grilled the meat and subjected it to analytical sensory evaluation. We also measured the amounts of moisture, protein, nucleic acid and glutamic acid. An increase in crude fat content increased the tenderness, juiciness, and fattiness in the meat quality evaluation. An increase in crude fat content reduced the crude protein and moisture contents; it also slightly reduced the nucleic acid and glutamic acid contents, although when the reductions in these umami components were assessed relative to the moisture content they changed little. Increasing the fat content up to a certain point greatly enhanced the umami intensity and beef flavor intensity in the meat quality evaluation and raised the overall evaluation score; the peak of the appropriate crude fat content for these purposes was about 36%.

Differences in the behavior of the crossbred steers of different sire lines of Japanese Black cattle

We determined differences in the behavior of the progeny of two major sire lines of Japanese Black cattle by recording the behavior of 35 and 70 half-sib steers of sires from fast (FG) and slow (SG) growing lines, respectively. Two sire lines of steers were mixed and allocated to nine pens with 11-12 animals per pen. The proportion of steers lying was significantly (P < 0.001) higher in the SG line (43.4 ± 5.7% compared to 40.3 ± 6.0%). The proportion of time spent eating concentrate feed (FG: 12.1 ± 2.3%; SG: 11.4 ± 2.1%), drinking (FG: 0.8 ± 1.1%; SG: 0.4 ± 0.6%), licking the feed trough (FG: 0.4 ± 0.6%; SG: 0.2 ± 0.4%) and performing tongue-playing (FG: 3.1 ± 4.6%; SG: 1.0 ± 1.9%) was significantly higher in FG, whereas the proportion of time spent resting (FG: 41.5 ± 12.8%; SG: 43.7 ± 10.9%) and performing self-licking (FG: 1.7 ± 1.4%; SG: 2.1 ± 1.3%) was higher in SG (all P < 0.05). These results show progeny of the FG sire engaged in more active behaviors compared to the progeny of the SG sire line.

Changes in beef sensory traits as somatic-cell-cloned Japanese black steers increased in age from 20 to 30 months

Changes in sensory traits of longissimus muscle (LM) from 20-30-month-old cattle were investigated using somatic cell clones of Japanese black steers slaughtered at 20-, 25- and 30-months-old (n=3, 4 and 4 respectively). The fat content of LM samples at 20, 25 and 30 months were 23.7, 38.7 and 41.1%, respectively. Soluble collagen content and collagen solubility at 20 months was greater than at 25 and 30 months. In terms of sensory traits, initial tenderness and juiciness at 25 months was greater than at 20 months, and fattiness at 25 and 30 months was greater than at 20 months. These results demonstrate that the changes in physicochemical traits of beef accompanying the differences in slaughter age affect the sensory traits although the desirable effects of the sensory traits do not continue throughout the entire fattening period.