Abstract The spittlebugs Mahanarva spectabilis economically challenges cattle production of neotropical regions, due to its voracious feeding on tropical grasses. Here, we evaluated biochemical responses of the interaction between M. spectabilis and the widely cultivated tropical grasses Brachiaria spp. (i.e., brizantha and decumbens) and elephant grasses (cvs. Roxo de Botucatu and Pioneiro), regarding lipoxygenases, protease inhibitors, phytohormones, and proteolytic activities in the midgut of M. spectabilis. The M. spectabilis-infested grasses increased lipoxygenases activity, except for cv. Pioneiro. The levels of the phytohormones jasmonic and abscisic acids were similarly low in all genotypes and increased under herbivory. Furthermore, salicylic acid concentration was constitutively higher in Brachiaria sp., increasing only in spittlebug-infested B. decumbens. M. spectabilis infestations did not induce increases of protease inhibitors in any forage grass type. The trypsin activity remained unaltered, and the total proteolytic activity increased only in B. decumbens-fed insects. Our findings revealed that most forage grasses exposed to spittlebugs activate the lipoxygenases pathway, resulting in increased abscisic and jasmonic acids. However, greater amounts of these hormones do not induce protease inhibitory activity in response to spittlebug attack. This knowledge certainly helps to guide future projects aiming at reducing the impact of spittlebugs on forage production.

The objective of this study was to evaluate bird responses to flavophospholipol at higher doses than those recommended by the Brazilian legislation. A trial was conducted with 900 male broilers divided into five doses of flavophospholipol: 0, 2, 4, 8 and 16 mg/kg. The performance evaluation was conducted weekly until 42 days of age. The evaluated parameters were: weight gain, feed conversion corrected for mortality, feed intake and mortality. At the end of experimental period, birds supplemented with growth promoter differed from the negative control for weight gain and feed conversion in the period from 1 to 42 days. Body weight gain and feed conversion were significantly higher for birds fed 16 mg/kg of flavophospholipol, compared with treatment without the growth promoter in the period from 1 to 21 days. In the accumulated period from 22 to 42 days, all doses were different for the negative control for feed conversion and body weight gain. The performance improvement was maximized at the dosage of 10.1 mg/kg for feed conversion ratio and 10.9 mg/kg for body weight gain by regression analysis. Flavomycin can be used as a growth promoter to improve feed conversion ratio and body weight gain in broilers from 1 to 42 days of age.