The economic value of days open in Holstein cows in Japan based on simulated changes in conception rate

Abstract

Increasing herd-life length and culling parity with increasing conception rate (CR) is necessary to increase lifetime profit from dairy cow production. Economic values of days open (DO) were determined by calculating changes in fertility traits, herd-life length, and milk yield when the simulated CR were changed in increments of 1% from −5% to 5% from the basal levels, which were obtained for Hokkaido and regions other than Hokkaido separately. When CR increased, number of artificial inseminations, DO, and milking length decreased. Furthermore, culling parity, and annual milk yield increased. Herd-life length increased in Hokkaido and decreased in the other regions. The economic values of CR were 1,623.8 to 946.8 yen and of DO were 857.4 to 399.0 yen. Relative economic values of milk yield to days open per genetic standard deviation were higher in the other regions than in Hokkaido where the economic effect of selection for DO was expected to be equal to selection for 305-day milk yield and herd life. If the survival rate of multipara cows in the other regions increases, then the economic value of DO would similarly increase in Hokkaido.

Effect of some non-genetic factors on the productivity and profitability of Holstein Friesian dairy cows

“…Available at www.veterinaryworld.org/Vol.14/January-2021/31.pdf Conception rate (CR) (S/C) directly determines the total herd profitability. Hence, to maximize the farm profitability, it is very important to increase the CR up to maximum level [19], reduce the cost of AI, and shorten the DO [20]. Improving the level of management is required for optimal reproduction performance [21].…”

Simulation of the lifetime productivity of a dairy herd in Japan according to the number of days to first service of cows

“…The MNS within each lactation was set as four or five, and non‐pregnant cows at MNS were culled after 450 days in lactation. According to Sasaki et al (2020), the cancelation rate of the next insemination until the fourth service ranges from 0% to 10%, and the actual value depends on the number of lactations and the geographic region (Hokkaido or other region). In the current study, we set 5% as the cancelation rate of the next service until MNS.…”

“…Moreover, farmers benefit from selling the calves. Consequently, lengthening calving intervals generally leads to economic loss (Sasaki et al, 2020).…”

“…The conception rates after 200 DFS and those in the fourth and later lactations were set as the same as those at 191 through 200 DFS and those in the third lactation, respectively. Whereas stated that conception rates at first service are relatively low before 50 DFS and gradually increase after 100 DFS,Sasaki et al (2020) reported that…”

様々な空胎日数および乾乳期間における乳量，仔牛生産および泌乳持続性の違いを考慮した乳用牛生涯生産効率のシミュレーション

“…Parameters for low calf sale price (¥60,255), artificial insemination cost, number of inseminations, and income from milk sales are referred from those of Sasaki et al (2019Sasaki et al ( , 2020. EBV class is defined as described in the legend for Figure 2.…”