Integrative Assessment of Ventilation Systems on Economic Efficiency, Milk Production, and Reproductive Performance in Dairy Cows

Arzu Peker¹Luisa Magrin^2*Severino Segato²Chiara Mondin²Şükrü Orkan¹Nursen Ozturk³Flaviana Gottardo²Samuele Trestini²

• ¹Ankara Universitesi Veteriner Fakultesi, Ankara, Türkiye
• ²University of Padua, Padua, Italy
• ³Istanbul Universitesi-Cerrahpasa, Avcılar, Türkiye

Due to global warming, temperate regions are increasingly experiencing heat waves, which negatively impact dairy cow welfare, productivity, and farm profitability. Ventilation systems (VS) are a common heat mitigation strategy, despite their high initial cost of investment. This study investigated the effects of heat stress (HS) and VS on dairy cows’ milk yield, and whether VS guarantees an economic benefit for farmers. The trial involved four dairy farms over three years: two years before and one after VS installation. We conducted an observational within-farm pre/post study, using two pre-installation years and 0.5–1 post-installation year per farm. Outcomes were analyzed at herd level: daily milk yield, bi-weekly milk quality, and monthly reproductive metrics. The Temperature-Humidity Index (THI) was calculated daily as a measure of HS, categorized as: comfort (<72), mild discomfort (72–79), discomfort (80–84), and alert (>84). Economic sustainability was assessed through partial budget analysis, accounting for extra feed, labor, and electricity costs. The presence of VS was associated with a significant increase in cows’ milk yield across all THI conditions (P<0.001). Fat and protein contents decreased with VS, consistent with the increased milk yield. However, their values were significantly lower under the most critical THI classes (P<0.001). Linear SCC scores were higher under discomfort and alert THI classes in the absence of VS, whereas they decreased slightly across THI classes when VS were used (P<0.001). The duration of lactation, days open, and number of services per pregnancy reached their highest values under THI alert conditions without the use of VS, and were significantly reduced with VS (P<0.001). Increased milk income with VS use was €12.39/day/cow in mild discomfort, €12.23 in discomfort, and €12.08 in alert conditions. Results showed wide variability in economic outcomes across farms and THI classes. Although differences in VS management prevented a definitive conclusion on return on investment, the findings suggest positive effects on cows’ productivity and farm profitability. However, a definitive ROI could not be stated given heterogeneity in fan size/spacing and cows-per-fan coverage, as well as farm-specific post-installation durations. Therefore, future cost-benefit analyses should consider additional factors to fully evaluate VS investments.