RESUMO A pesquisa foi realizada com o objetivo de avaliar os diferentes níveis de energia metabolizável (3050, 3100, 3150, 3200 e 3250 kcal.kg-1) na dieta de frango de corte de 22 a 42 dias de idade, mantidos em ambiente de estresse térmico. Trezentos pintos, machos com 814,7 g de peso médio inicial, foram distribuídos em delineamento experimental inteiramente casualizado, com cinco tratamentos, seis repetições e dez aves por unidade experimental. Os níveis de energia metabolizável das rações não influenciaram (P>0,05) as variáveis de desempenho conversão alimentar (CA), ganho diário de peso (GDP) e consumo diário de ração (CDR), nas duas fases estudadas, para as características de carcaça não houve diferenças estatísticas para os rendimentos de: carcaça, peito, coxa, sobrecoxa, coração, asa e dorso, sendo observadas diferenças para as variáveis, rendimento de moela e gordura abdominal. Foi observado aumento linear na porcentagem de gordura abdominal de acordo com o aumento dos níveis de energia na ração. O nível 3100 Kcal.kg-1 de energia metabolizável é o nível indicado nesta pesquisa por apresentar menor teor de gordura abdominal e menor custo por quilo de ração.

ABSTRACT The research was carried out with the objective of evaluating different levels of metabolisable energy (3050, 3100, 3150, 3200 and 3250 kcal.kg-1) in the diet of 22-to-42-day-old broilers kept in an environment of thermal stress. Three hundred male chicks weighing 814.7 g initial average weight were distributed in a completely randomised design with five treatments, six replications and ten birds per experimental unit. Feed metabolisable energy levels did not influence (P > 0.05) the performance variables of feed conversion, daily weight gain and daily feed intake in the two phases studied. There were no statistical differences in carcass yields: carcass, chest, thigh, drumstick, heart, wing and back. Differences were observed for the two variables gizzard yield and abdominal fat. A linear increase in the percentage of abdominal fat with an increase in energy levels in the diet was observed. The 3100 kcal.kg-1 level of metabolisable energy is the level indicated by this research because it results in lower abdominal fat content and lower cost per kilo of feed.

The microcephaly epidemic in Brazil generated intense debate regarding its causality, and one hypothesised cause of this epidemic, now recognised as congenital Zika virus syndrome, was the treatment of drinking water tanks with pyriproxyfen to control Aedes aegypti larvae. We present the results of a geographical analysis of the association between the prevalence of microcephaly confirmed by Fenton growth charts and the type of larvicide used in the municipalities that were home to the mothers of the affected newborns in the metropolitan region of Recife in Pernambuco, the state in Brazil where the epidemic was first detected. The overall prevalence of microcephaly was 82 per 10,000 live births in the three municipalities that used the larvicide Bti (Bacillus thuringiensis israelensis) instead of pyriproxyfen, and 69 per 10,000 live births in the eleven municipalities that used pyriproxyfen. The difference was not statistically significant. Our results show that the prevalence of microcephaly was not higher in the areas in which pyriproxyfen was used. In this ecological approach, there was no evidence of a correlation between the use of pyriproxyfen in the municipalities and the microcephaly epidemic.