ABSTRACT This study evaluated the laying performance, egg quality, and economic responses of Japanese quails in the late laying phase fed diets differing in energy density and digestible lysine levels under hot and humid tropical conditions. Six hundred 175-day-old laying Japanese quails were distributed in a completely randomized design with a 3 × 4 factorial arrangement, totaling 12 treatments with five replicates and 10 birds per experimental unit. Dietary treatments were formulated to contain three energy densities (2600, 2875, or […]

This work aimed to study the annual variation of temperature of the coat surface and other traits of coat in Holstein cows managed in a tropical environment by separately considering black coat and white coat. It was measured the coat thickness (mm) characteristic, hair length (mm), hair number (hair/cm2) and coat surface temperature on 191 crossbred cows with 7/8 and 31/32 Holstein composition distributed in 3 herds in a semi-arid environment. Less dense coats with shorter, flattened hair occurred predominantly […]

Nine lactating Holstein cows with average 526 ± 5 kg of BW, five predominantly black and four predominantly white, bred in a tropical region and managed in open pasture were observed to measure cutaneous and respiratory evaporation rates under different environmental conditions. Cows were separated in three weight class: 1 (<450 kg), 2 (450-500 kg) and 3 (>500 kg). Latent heat loss from cutaneous surface was measured using a ventilated capsule; evaporation in the respiratory system was measured using a […]

Data from 359 Holstein and 54 Jersey cows (total of 1359 observations) collected in commercial herds in the northeast of Brazil were used to evaluate six environmental stress indexes. The selection criterion was the correlation between the index value with the rectal temperature (RT) and the respiratory rate (RR) of cows. Both Temperature-Humidity Index (THI) and Black Globe-Humidity Index (BGHI) had the lowest correlations with animal RT and RR. The selected indexes were the Equivalent Temperature Index (r = 0.293 […]

The variation of cortisol and thyroid hormones in Corriedale sheep bred in a tropical environment was evaluated. Fourteen males and seven females were observed in a climatic chamber at 45ºC for nine days, eight hours per day. Rectal temperature (TR), respiratory rate (FR), air temperature (TA) and air humidity (PV) were recorded. The animals were ranked according to their responses for TR and FR and then the five highest (A group) and five lowest (NA group) ranked animals were selected. […]