The objective of this study was to investigate the relationship between marbling and serum leptin concentrations. First, we compared serum leptin concentrations between Japanese Black cattle and Holstein calves, and found that the mean serum concentration was significantly higher (P < 0.05) in Japanese Black cattle (2.67 ± 0.41 ng/mL, n = 13) than in Holstein calves (1.79 ± 0.43 ng/mL, n = 5). We then examined the effects of roughage intake or vitamin A on the serum leptin concentrations in Japanese Black cattle. Although the leptin concentrations for the high roughage group were significantly higher than those for the low roughage group at 4, 7 and 20 months old, there was no significant difference in the carcass characteristics of the two groups. In addition, although there was a significant difference in the marbling score between the high vitamin A group and low vitamin A group, there was no significant difference in serum leptin concentrations between the groups. These results suggest that although serum leptin concentrations were not significantly correlated to the marbling scores they may be related to the genetic advantage for marbling in Japanese Black cattle.

No abstract

This study aimed to evaluate the e#ects of a molt diet on molt induction and the post-molt performance of laying hens. White Leghorn hens (age, 0, wk) were randomly divided into three groups (two experimental, one control). After a .-wk preliminary period, one group (control) was continuously fed a corn-soybean-based layer ration ad libitum. Molting was induced in the other groups by starvation (MS) or with feed (MF). In the MS group, the feed was withdrawn for , wk; this was followed by feeding of a layer ration on alternate days for + wk and then ad libitum. The MF group was fed ad libitum a low-protein and low-energy diet based on corn, wheat bran, and corn gluten feed for . wk; this was followed by ad libitum feeding of a layer ration. Egg production, egg quality, and feed intakes were measured throughout the experimental period; ovary and oviduct weights and heterophil: lymphocyte (H:L) ratios were measured during molting. During molting, the feed intake in the MF group was lower than that of the control; body weights of the molted groups were significantly reduced. Additionally, the MS group totally ceased egg production within 2 d; in the MF group, egg production decreased to -.2ῌ by d +*. On d +* of molting, the H:L ratio of the MF group was lower than that of the MS group. On d +., the ovaries and oviducts of the molted groups were distinctly lighter than those of the control. Throughout the post-molt period, egg production and egg shell thickness of the molted groups improved; but there were no significant di#erences. Additionally, the eggs of the MF group were heavier than those of the MS and control groups. This study suggests that feeding of a low-protein and low-energy diet e#ectively induces molting and increases post-molt production.