RESUMO A inclusão do enriquecimento ambiental na criação convencional dos frangos de corte pode causar aumento na mobilidade, massa óssea e músculos. O objetivo desta pesquisa foi avaliar o uso do enriquecimento ambiental na criação de frangos de corte em diferentes idades e sua influencia no desempenho, morfometria, rendimento e peso das partes. Foi utilizado o delineamento inteiramente casualizado em esquema de parcelas subdivididas, sendo que, nas parcelas foram alocados os tratamentos presença (T1) e ausência (T2) de enriquecimento ambiental e nas subparcelas as idades dos frangos (1, 7, 14, 21, 28, 35 e 42 dias), com 56 aves em cada tratamento (T1 e T2). Os dados obtidos foram analisados pelo modelo linear de efeitos fixos e comparados pelo teste de médias de Tukey. Os animais foram criados em ambiente controlado, dividido em quatro boxes com dimensões: 1,5 × 1,0 × 0,7 m, contendo cama de palha de arroz. Em T1 utilizou-se uma escada com poleiro no topo distribuída a cada 1,5 m2. O uso de enriquecimento ambiental não influenciou no desempenho zootécnico dos frangos de corte. As propriedades morfométricas, peso das partes e o peso corporal dos frangos de corte aumentaram, devido ao uso do enriquecimento ambiental; essa melhoria foi observada na fase final de criação das aves. O enriquecimento ambiental foi benéfico para ganho de massa muscular e óssea nas principais partes comerciais da carcaça de frango, além de reduzir o coeficiente alométrico dos peitos dos frangos.

ABSTRACT The inclusion of environmental enrichment in conventional broiler rearing can increase mobility, bone mass and muscle. This research aimed to evaluate the use of environmental enrichment in the rearing of broilers at different ages and its influence on performance, morphometry, yield and weight of the parts. It was used the completely randomized design in split-plot scheme, being the plots the treatments presence (T1) and absence (T2) of environmental enrichment and the subplots the broiler ages (1, 7, 14, 21, 28, 35 and 42 days), with 56 chicks in each treatment (T1 and T2). Data obtained were analyzed by the linear effect model of fixed effects and compared by Tukey’s test of means. The animals were raised in a controlled environment, divided into four boxes with dimensions: 1.5 × 1.0 × 0.7 m, containing rice straw bed. In T1 a ladder with a perch on top was used, distributed every 1.5 m2. Environmental enrichment used did not influence broiler’s zootechnical performance. Broilers’ morphometric properties, parts weight and body weight increased due to environmental enrichment and, improvement was observed in chicks rearing’s final phase. The environmental enrichment was beneficial for muscle and bone mass gain in the main commercial parts of the chicken carcass, in addition to reducing the allometric coefficient of the breasts in chickens.

Acute heat stress may affect the quality of broilers meat, however there are no reports considering thermal conditions commercially available in Brazil. In this way, the present work aimed to fill this gap of industrial relevance. Broilers of commercial strain (Cobb 500, n = 540) were randomly assigned to two thermal conditions: acute heat stress (AHS; 35°C; 75 - 85% relative humidity) and not-heat-stress (NS; 22ºC; 83 ± 6.6% relative humidity), for 2 hours prior to slaughter. The mortality rate for AHS broilers reached 37%, which was greater than 5.2% verified for NS. According to the mean values, the broiler chickens were not totally affected in the parameters of pH24h, lightness (L*), cooking loss, and shear force. However, the distributions of data show great variability in the values of pH24h, L* and water holding capacity (WHC) for AHS broilers. It is suggested that AHS broilers, at severe conditions which result in increased mortality, present breast meat with greater incidence of higher pH24h, and lower lightness and WHC values.

We describe an efficient in vitro assay to test growth hormone effects on mRNA levels and fatty acid synthase (FAS, EC. 2.3.1.85) activity. Swine adipose tissue explants were long-term cultured in medium containing growth hormone and FAS mRNA levels and enzyme activity were measured. We quantified FAS transcripts by competitive reverse transcriptase PCR (RT-PCR) using total RNA from cultured adipose tissue explants and RT-PCR standard-curves were constructed using a cloned 307 bp segment of native FAS cDNA and a shorter fragment from which a 64 bp (competitor, 243 bp) internal sequence had been deleted. A known amount of competitor was added to each PCR as an internal control and µ-actin transcripts were also measured to correct for differences in total RNA extraction and reverse transcription efficiency. In cultures with added growth hormone FAS mRNA levels decreased 70% (p < 0.01) and FAS enzyme activity decreased 22% (p < 0.05). These in vitro growth hormone effects were consistent with those observed in vivo, showing that in vitro adipose tissue culture combined with RT-PCR is a useful and accurate tool for studying growth hormone modulation of adipose tissue metabolism. This technique allowed the diagnosis of lower levels of FAS mRNA in the presence of growth hormone and these low levels were associated with decreased FAS activity in the adipose tissue explants.