The objective of this study was to estimate breeding values and genetic parameters for predicted nitrogen excretion, phosphorus excretion and methane-related traits (predicted environment-related traits) and to investigate the relationships between the predicted environment-related traits and 4 residual feed intake (RFI) traits. The environment-related traits were predicted using the records (phenotypic values) such as initial and final body weights, average daily gain, and intakes of total digestible nutrient (TDN), crude protein (CP), concentrate and roughage collected from Japanese Black bulls’ performance test (112 days) scheme from 2007 to 2020. The records of Japanese Black bulls used for analyses were 2,729, 1,111 and 1,400 for predicted nitrogen excretion, phosphorus excretion and methane-related traits, respectively. The heritability estimates for the predicted environment-related traits were moderate to high (ranged from 0.40 to 0.59). The genetic relationships among estimated breeding values (EBVs) of predicted nitrogen excretion, phosphorus excretion and methane production were positive and favorable. There were positive and favorable genetic relationships between predicted nitrogen excretion and RFI(CP) and between predicted methane production and RFI(TDN). Our results suggest that the predicted environment-related traits are heritable and decreases of the environmental-related traits could be expected through the selection of bulls based on some RFIs.

In recent years, the ratio of monounsaturated fatty acids to the total fatty acids (MUFA%) has attracted attention due to the positive correlation with the flavor of the beef meat. However, very little research has been done on the relationship between MUFA% and carcass prices. This study was designed to explain the environmental effect on MUFA% and the effect of MUFA% on carcass unit price of Japanese Black cattle. The data were obtained from cattle that were shipped to the market in Hokkaido from 2013 to 2020 in this study. Carcass traits and image analysis traits, which was marbling percentage, coarseness index and new fineness index taken of the 6-7th rib of the carcass, MUFA% classified in units of 5% (4grades : <55%, 55～60%<, 60～65%<, 65%≦) were used for analysis. Least square means of MUFA% in slaughter date had decreased year by year. Phenotypic correlation coefficients were calculated to determine the relationship among MUFA% and each trait, and BFS No. was the highest (0.20). Least square means of unit prices in MQ (meat quality grades) 2 to 4 rose in association with increasing of MUFA% level (MQ3 : P<0.01). On the other hand, only MQ5 showed a decrease in unit prices with higher MUFA% (P<0.01). Investigated appearance ratio of BMS No. in each MUFA% level in MQ5 showed BMS No. 8 and No. 12 were in the same range in less than MUFA55% level, whereas decreasing of the appearance ratio with the rise of BMS No. in moreover MUFA65% level was indicated (BMS No. 12 : P<0.01). In addition, all of average of BFS No. were increased in each BMS No. with increasing MUFA% level (BMS No. 8-11 : P<0.01, BMS No. 12 : P<0.05). In conclusion, carcass unit prices increased with higher MUFA% in range of MQ2-4, while in only MQ5 it decreased. There was the positive correlation between MUFA% and BFS No., thus fat color tends to get dark with increasing of MUFA%. According to these results, it is thought that it is difficult to be evaluated higher BMS No. in high-MUFA% level as a boundary with muscle and marbling is ambiguous. It needs to explore appropriate MUFA% from the point of view of carcass price.

The effects of partly mixed ration (PMR) containing ensiled rice with different crushed particle sizes on feed intake, lactation performance, plasma metabolites and ruminal fermentation characteristics of dairy cows were investigated. The ensiled rice was crushed using a double-roller crusher with a crushing roll interval of 1.0 mm (cracked rice) or 0.2 mm (ground rice), respectively. The proportion of ensiled rice that passed through a 2 mm sieve was 13.5% in the cracked rice and 54.2% in the crushed rice. Six lactating Holstein cows were used in a 2×2 cross over design and fed PMR containing 18% of each ensiled rice as dry matter basis. There was no difference in feed intake, milk yield and milk composition of the experimental cows between the two groups. There was no significant difference in plasma metabolites and of experimental cows between the two groups.