Bl 1500

All birds were individually weighed (Sartorius BL 1500 measuring to the nearest 0.1 g) once per week during the experiment (weeks one to six). The increase in grams per week was used to calculate growth rate. At the end of the experiment (week six), tarsus length and width were measured following the procedure described by Campo and Prieto [41 ] with a digital calliper (Biltema, Sweden) to the nearest 0.01 mm. Body weight and tarsus measures were analysed separately but also combined to calculate body condition (calculated as the ratio: body weight/tarsus length). Relative fluctuating asymmetry (RFA) was calculated as the absolute difference between the right and left legs divided by the mean between the left and right measures [42 (link),43 ]. These morphological indicators were selected because of their previously documented association to measures of individual quality, health status and stress levels [19 (link), 42 (link)–46 ].

Mice were weighed every 3 days from the beginning (day 1) to the end of day 21 of the cold exposure by using an electronic balance (±0.1 g; BL 1500; Sartorius, Göttingen, Germany) and body weight change was calculated. We measured rectal temperature in mice that were housed at ambient temperature by using a medical precision thermometer at 20:00 p.m. every 3 days and we measured ambient temperature before cold stress in mice. Body temperature was tested after the body weight testing (the body temperature taken while they were in the cold climate), by inserting a mercury thermometer into the rectum of the mice for 5 min, and each mouse was sterilized by 70% alcohol disinfection around the anus before the body temperature test. The thermometer was sterilized between the temperature tests of each mouse.

Six birds at 35 days of age, from each treatment representing all replication, were randomly taken and slaughtered to determine physical characteristics (pH, color, tenderness, and WHC) and inner body (proventriculus, liver, heart, pancreas, and intestinal morphology) based on the method described by Attia et al. [7 ]. Additionally, the lymphoid organs were removed and weighed using a digital scale (Sartorius BL 1500). Then, the results were reported as inner body organ weight (%).