Feasibility and validity of animal-based indicators for on-farm welfare assessment of thermal stress in dairy goats

This investigation tested the feasibility and validity of indicators of cold and heat stress in dairy goats for on-farm welfare assessment protocols. The study was performed on two intensive dairy farms in Italy. Two different 3-point scale (0–2) scoring systems were applied to assess cold and heat stress. Cold and heat stress scores were visually assessed from outside the pen in the morning, afternoon and evening in January–February, April–May and July 2013 for a total of nine sessions of observations/farm. Temperature (°C), relative humidity (%) and wind speed (km/h) were recorded and Thermal Heat Index (THI) was calculated. The sessions were allocated to three climatic seasons, depending on THI ranges: cold (<50), neutral (50–65) and hot (>65). Score 2 was rarely assessed; therefore, scores 1 and 2 were aggregated for statistical analysis. The amount of goats suffering from cold stress was significantly higher in the cold season than in neutral (P < 0.01) and hot (P < 0.001) seasons. Signs of heat stress were recorded only in the hot season (P < 0.001). The visual assessment from outside the pen confirms the on-farm feasibility of both indicators: No constraint was found and time required was less than 10 min. Our results show that cold and heat stress scores are valid indicators to detect thermal stress in intensively managed dairy goats. The use of a binary scoring system (presence/absence), merging scores 1 and 2, may be a further refinement to improve the feasibility. This study also allows the prediction of optimal ranges of THI for dairy goat breeds in intensive husbandry systems, setting a comfort zone included into 55 and 70.