RESUMEN
The aims of this study were (i) to evaluate the effect of density, lineage, age, and time of day on dorsal surface temperature and (ii) to evaluate the effect of density and lineage on performance and carcass condemnations in broiler grillers. The evaluations were carried out in barns with the Dark House system, with two densities, 17 and 19 chickens/m2 and two lineages, Cobb and Ross. The dorsal surface temperature of the chickens was measured by infrared thermography at 7, 14, 21, 23, 25 and 27 days of age, four times a day. The average daily weight gain, feed conversion, mortality, partial carcass condemnations, as well as those due to arthritis and dermatosis were also evaluated. The highest dorsal surface temperatures were observed in Cobbs housed at a density of 17 chickens/m2, and in Ross housed at a density of 19 chickens/m2. Cobbs housed at a 17 chickens/m2 density showed the lowest feed conversion compared to Ross at the same density. Ross showed higher dorsal surface temperatures when compared to Cobbs at 14, 21, and 27 days. Cobbs showed higher percentages of partial carcass condemnation and arthritis compared to Ross. The higher density of broiler grillers in the Dark House system does not influence the dorsal surface temperature, performance, dermatosis, arthritis, and partial carcass condemnations.
RESUMEN
The effect of different percentages of Duroc genes in crossbreeding (5, 50 and 100%), the gender (immunocastrated males - ICM and females) and their interaction was evaluated on growth, carcass and meat quality traits for pigs. Crossbreds (50% Duroc) had greater average daily feed intake, hot carcass weight and backfat thickness but lower meat yield when compared to 5% Duroc crossbreds and purebred (100% Duroc) animals (P < 0.05). Purebred (100% Duroc) animals had the lowest backfat thickness and subcutaneous fat thickness, and the greatest muscle depth and meat yield (P < 0.05). ICM animals had better feed conversion, greater average daily gain, hot carcass weight and amount of meat, and lower hot carcass yield, cold carcass weight, Longissimus thoracis depth, rib with belly and ham weights compared to females (P < 0.05). Marbling scores were greater in purebred (100%) animals (P < 0.05). The meat from 50% Duroc crossbreds and 100% Duroc purebred pigs was more reddish pink in color than 5% Duroc crossbreds (P < 0.05). Also, marbling scores were greater for females compared to ICM (P < 0.05). Purebred (100% Duroc) animals required more medications during production (P < 0.05).