No abstract

Differences in free fatty acids (FFAs) chemical composition of insects may be responsible for susceptibility or resistance to fungal infection. Determination of FFAs found in cuticular lipids can effectively contribute to the knowledge concerning insect defense mechanisms. In this study, we have evaluated the susceptibility of three species of cockroaches to the entomopathogenic fungi Metarhizium anisopliae (Metschnikoff) Sorokin by topical application. Mortality due to M. anisopliae was highly significant on adults and nymphs of Blattella germanica L. (Blattodea: Blattellidae). However, mortality was faster in adults than in nymphs. Adults of Blatta orientalis L. (Blattodea: Blattidae) were not susceptible to the fungus, and nymphs of Blaptica dubia Serville (Blattodea: Blaberidae) were more susceptible to the fungus than adults. The composition of cuticular FFAs in the three species of cockroaches was also studied. The analysis indicated that all of the fatty acids were mostly straight-chain, long-chain, saturated or unsaturated. Cuticular lipids of three species of cockroaches contained 19 FFAs, ranging from C14:0 to C24:0. The predominant fatty acids found in the three studied species of cockroaches were oleic, linoleic, palmitic, and stearic acid. Only in adults of Bl. orientalis, myristoleic acid, γ-linolenic acid, arachidic acid, dihomolinoleic acid, and behenic acid were identified. Lignoceric acid was detected only in nymphs of Bl. orientalis. Heneicosylic acid and docosahexaenoic acid were identified in adults of Ba. dubia.

No abstract

No abstract

Thirty-six male Holstein calves were in an experiment with 2 X 2 factorial design with the objective of comparing management systems and milk feeding. Housing systems were similar except calves on A system were housed in pens .66 m wide with grated floors whereas calves on B system were in pens that were 1.36 m wide with solid floors bedded with straw. Within each management system nine calves were fed milk at 8% of body weight and nine calves at 12% of body weight. There was no interaction between management system and feeding percent. Preweaning calves fed more milk gained faster (.64 versus .50 kg/day) compared with calves fed less. Management system did not influence body weight gain or feed conversion prior to weaning, but postweaning A system resulted in slower gains (.74 versus .90 kg/day) and less favorable feed conversion (2.00 versus 1.77 kg dry matter intake/kg body weight gain) than calves housed under the B system. Eosinophil count was higher during 5th and 7th wk of the experiment for calves housed in A compared with B system. Measurements of body weight gain and feed conversion were effective in differentiating between two housing systems for calves.