The objectives of this study were to evaluate the environmental impacts of a beef cow–calf system using a life cycle assessment (LCA) method and to investigate the effects of scenarios to reduce environmental impacts on the LCA results. The functional unit was defined as one marketed beef calf, and the processes associated with the cow–calf life cycle, such as feed production, feed transport, animal management, the biological activity of the animal and the treatment of cattle waste were included in the system boundary. The present results showed that the total contributions of one beef calf throughout its life cycle to global warming, acidification, eutrophication and energy consumption were 4550 kg of CO2 equivalents, 40.1 kg of SO2 equivalents, 7.0 kg of phosphate (PO4) equivalents and 16.1 GJ, respectively. The contribution of each process to the total environmental impact in each environmental impact category showed a similar tendency to the contribution of each process in each environmental category reported in the case of the beef fattening system as a whole. The results from this analysis showed that shortening calving intervals by 1 month reduced environmental impacts by 5.7–5.8% in all the environmental impact categories examined in the current study, and increasing the number of calves per cow also reduced environmental impacts in all the categories, although the effects were smaller.

A whole-genome scan was conducted using 132 microsatellite markers to identify chromosomal regions that have an effect on teat number. For this purpose, an experimental cross between Chinese Meishan pigs and five commercial Dutch pig lines was used. Linkage analyses were performed using interval mapping by regression under line cross models including a test for imprinting effects. The whole-genome scan revealed highly significant evidence for three quantitative trait loci (QTL) affecting teat number, of which two were imprinted. Paternally expressed (i.e., maternally imprinted) QTL were found on chromosomes 2 and 12. A Mendelian expressed QTL was found on chromosome 10. The estimated additive effects showed that, for the QTL on chromosomes 10 and 12, the Meishan allele had a positive effect on teat number, but, for the QTL on chromosome 2, the Meishan allele had a negative effect on teat number. This study shows that imprinting may play an important role in the expression of teat number.

Field records from 14,380 Japanese Brown steers by 92 sires were used to estimate genetic parameters for growth and carcass traits. Multipletrait restricted maximum likelihood (REML) procedures accounting for relationships among sires were used in estimating (co)variance components among average daily gain during fattening periods (ADG), carcass weight (CWT), longissimus muscle area (LMA), rib thickness (RT), marbling score (MS), and subcutaneous fat thickness (SFT). Heritability estimates on an age-constant basis were .22, .37, .38, .26, .40, and .35 for ADG, CWT, LMA, RT, MS, and SFT, respectively. Estimated genetic correlations (rg) among ADG, CWT, and RT were positive and moderately high (.48 to .85). The rg between MS and SFT was -.12.

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A deterministic simulation model was constructed to develop breeding objectives and estimate biological and economic values. The model simulates life-cycle production of a breeding cow and growth performance of her offspring. Input variables are divided into four categories: animal traits, nutritional variables, management variables and economic variables. The economic variables assume typical beef cattle production in Japan. The outputs from the model include cow-calf performance, feedlot performance and biological and economic efficiency. The model's ability to simulate herd composition, food intake of cow and calves, cow body-weight changes, empty body and carcass composition of feedlot animals and production efficiencies is illustrated.