Targeted reproductive management for lactating Holstein cows: Economic return.

Abstract

Targeted reproductive management (TRM), employing automated monitoring devices (AMD), is as an alternative to the blanket adoption of ovulation synchronization protocols (OvSP) for first postpartum artificial insemination (AI) and a means of reducing the use of OvSP for re-AI of non-pregnant cows. We hypothesized that a TRM that relies heavily on AI of cows on AMD-detected estrus increases improves reproductive performance and economic return. Early-postpartum estrus characteristics of multiparous (n = 941) cows were evaluated at 40 and 41 DIM (Herds 1and 2, respectively) and early-postpartum estrus characteristics of primiparous (n = 539) cows were evaluated at 54 and 55 DIM (Herds 1 and 2, respectively). Cows in the control treatment were enrolled in the Double-Ovsynch protocol and AI at fixed time (TAI) at 82 and 83 DIM (primiparous cows in Herds 1 and 2, respectively) and 68 and 69 DIM (multiparous in Herds 1 and 2, respectively). Cows enrolled in the TRM treatment were managed according to early-postpartum estrus characteristics as follows: 1. Cows with ≥1 intense estrus (heat index ≥70; 0 = minimum, 100 = maximum) were AI upon AMD detected estrus for 42 d and, if not AI, were enrolled in the Double-Ovsynch, 2. Cows without an intense estrus were enrolled in the Double-Ovsynch at the same time as cows in the control treatment. Control cows were re-AI based on visual or patch aided detection of estrus, whereas TRM cows were re-AI as described for control cows with the aid of the AMD. All cows received a GnRH injection 27 ± 3 d after AI and, if diagnosed as non-pregnant, completed the 5-d Cosynch protocol and received TAI 35 ± 3 d after insemination. The hazard of pregnancy was greater for cows in the TRM treatment [adjusted hazard ratio = 1.17, 95% confidence interval = 1.05, 1.32], resulting in more cows from the TRM treatment starting a new lactation (82.6 vs. 77.2%) and fewer of them sold (15.5 vs. 20.8%). Treatments did not differ regarding total milk yield (control = 12,782.1 ± 130.6 kg, TRM = 13,054.7 ± 136.1 kg). The gross profit ((milk income + sale value + subsequent lactation calf value) - (feed cost + replacement cost + fixed cost + reproductive management cost)) of cows in the TRM treatment was $108 greater than the control treatment ($3,061.6 ± 45.9 vs. $2,953.8 ± 45.2). According to a Monte Carlo stochastic simulation, the mean (±SD) difference in gross profit was $87.8 ± 12.6/cow in favor of the TRM treatment and 95% of the scenarios ranged from $67.2/cow to $108.5/cow (minimum = $30.2/cow, maximum = $141.1/cow). In the conditions of the current experiment, the TRM treatment improved the gross profit of Holstein cows because the increased hazard of pregnancy changed culling dynamics, reducing replacement cost and cow sales and increasing calf value. The findings of the current experiment emphasize the importance of efficient reproductive management and its substantial economic implications, particularly in the context of high-producing Holstein cows.