Changes in Livestock Weather Security Index (Temperature Humidity Index, THI) During the Period 1917–2016 in Veracruz, Mexico

In Veracruz, raising livestock takes place in an environment that offers little comfort, and this condition has worsened since 1990. Projections of climate change scenarios for Veracruz, Mexico, show increases in temperature; central Veracruz will be the most affected. Analysis of daily temperatures (ºC) and relative humidity (%) for the period 1917–2016 was carried out to obtain the Livestock Weather Security Index (LWSI) using the Temperature and Humidity Index (THI) provided by the forecast center of the Gulf of Mexico and to determine changes in THI. Cattle comfort was obtained with the equation: THI = 1.8 × T + 32-(0.55–0.55 × HR) × (1.8 × T-26); Where “T” is temperature (°C) and “RH” relative humidity (%). THI values were interpreted as ≤ 74 Comfort, 75–78 Alert, 79–83 Dangerous and ≥ 84 Emergency. Periods of 30 years known as Normal I: (1917–1930), II: (1931–1960), III: (1961–1990), IV: (1991–2016) were made. THI means in the time periods were (I) 75.15 ± 0.061, (II) 75.80 ± 0.041, (III) 75.55 ± 0.044, and (IV) 76.62 ± 0.049 (p < 0.05). Percentage (%) of days for THI categories in each Normal was (I) 34.15, 46.69, 19.14, 0.0; (II) 30.84, 42.13, 27.01, 0.0; (III) 32.53, 39.67, 27.78, 0.009; (IV) 27.54, 34.10, 38.17, 0.17 for Comfort, Alert, Dangerous and Emergency (p < 0.05). Comfort has been reduced in recent years; increases in the percentage of days with THI > 79 are expected.