Impacts of heat peaks in France on the performances of dairy goats housed in an insulated roof shed
Résumé
Thermal comfort of animals and breeders is decisive in ensuring the sustainability of goat and sheep farming systems. Climate projections show that summer periods will be increasingly hot and will lead to changes in feeding and breeding management. The objective of this study is to measure impacts of heat peaks on dairy goats housed in an insulated roof shed. Data were collected from June 1st to September 15th, 2022 in the INRAE FERLus Experimental Unit based in Lusignan (New Aquitaine- 46.43°N, 0.12°E). Monitoring was conducted on 3 batches of animals: 1 group is grazing and breeds during sexual season, 1 group is grazing and breeds during the off-season and 1 group is housed inside year-round and breeds in the off-season. Recorded data included precise description of housing and zootechnical data: feed (distributed and refusal), milk production (collective and individual quantity and quality), watering, sanitary, behaviour, grazing time, panting score (16 goats per batch). Sensors were used to record hourly temperatures and humidity in 2 places in the building, then calculate the temperature hygrometry index (THI). Meteorological data were collected by a 300 m-distant station. In conditions defined like hot (>27 °C), the temperature inside the shed was lower by 1.6 °C than outside, and when the temperature was >36 °C, the temperature inside was lower by 3.2 °C. In neutral condition (<27 °C), the temperature inside was higher by 3.7 °C which means that this building buffers the impact of high temperatures but also when the temperature drops. In 2022, 3 periods of 1 or 2 days with a THI above 77 were observed. Milk production was 6.6% lower during 3 days following the THI>77 period than the preceding 3 days (3.76 vs 3.51 kg/d). This drop was still significant over a period of 5 days. The mean THI was not different (72±2.4) between the 3 or 5 day-periods before or after THI>77, and no differences were observed on the dry matter intake (2.74±0.24 kg/d) or the water consumption (7.3±2.4 l/d). This study will be repeated in 2023 after the addition of a ventilation system.