Chemical composition and rumen degradability of three corn hybrids treated with insecticides against the European corn borer ( Ostrinia nubilalis)

• Published in: Animal feed science and technology Vol. 155; no. 1; pp. 25 - 32
• Main Authors: Masoero, F., Gallo, A., Zanfi, C., Giuberti, G., Spanghero, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 20-01-2010; [New York, NY]: Elsevier Science; Elsevier
• Subjects: animal performance; Biological and medical sciences; carbohydrate content; chemical composition; Corn silage; corn stover; crop yield; digestibility; European corn borer; Feed and pet food industries; fiber content; Food industries; forage; forage quality; Fundamental and applied biological sciences. Psychology; gas production (biological); hybrids; in vitro digestibility; insect pests; Insecticide; neutral detergent fiber; nutritive value; Ostrinia nubilalis; pyrethroid insecticides; Rumen degradability; rumen fermentation; ruminants; seeds; starch; Zea mays; aNDF; ADF; Insecticide; ECB; RSE; DM; European corn borer; CP; Corn silage; NDFD; ha; Rumen degradability; OM; Digestive system; Insecta; Crambidae; Pesticides; Hybrid; Corn; Rumen; Ostrinia nubilalis; Silage; Arthropoda; Lepidoptera; Cereal; Chemical composition; Invertebrata
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2009.10.001

This experiment determined the chemical composition, rumen degradability (aNDF in stalks and starch in kernels) and
in vitro gas production of kernels from three corn hybrids treated (TT) or not treated (control, CTR) with insecticides against the European corn borer (ECB,
Ostrinia nubilalis). Two whole-plant silage hybrids belonging to the FAO rating 600 and 700 maturity class (S600 and S700, respectively) and one selected for grain production (G600, FAO rating 600, Dekalb-Monsanto Agricoltura S.p.A., Lodi, Italy) were sown in two main plots (TT and CTR) of an experimental field. Two subsequent treatments of pyrethroids (25 and 1.2
g/ha of cyfluthrin and deltamethrin, respectively) were applied to the TT plots. The insecticide treatment reduced the number of damaged plants (4.5 broken plants/plot
versus 0.3 broken plants/plot,
P<0.01) and increased the total grain yield by 11% (13.8
t/ha
versus 12.4
t/ha), while hybrids did not differ. ECB larvae which bored into the stalk tunnels modified the chemical composition of stalks and kernels. In stalks, total sugars content (
i.e. glucose, fructose, sucrose) was about twice that in TT
versus CTR plants (123
g/kg
versus 60
g/kg DM,
P<0.01), while aNDF content was higher in CTR stalks (765
versus 702
g/kg DM,
P<0.01). DM degradability after 48
h of incubation of stalks was higher in TT than in CTR, both
in vitro (0.360
versus 0.298,
P<0.01) and
in situ (0.370
versus 0.298,
P<0.05), while there were no differences in aNDF degradability. Kernels from TT plots contained less DM (615
g/kg
versus 651
g/kg,
P<0.01) and more CP (84
g/kg and 78
g/kg DM,
P<0.05) than those from CTR plots, while
in situ rumen starch disappearance and
in vitro gas production were similar. Corn hybrid selected for yield of grain (G600) differed from S600 and S700 due to a higher (
P<0.01) content of aNDF, ADF and lignin(sa) in the stalks, and a higher starch content (696
g/kg
versus 674 and 671
g/kg DM,
P<0.01) and CP (87
g/kg
versus 77 and 76
g/kg DM,
P<0.05) in grain. The G600 hybrid produced stalks with a lower (
P<0.01) aNDF rumen degradability than the S600 and S700.
On field ECB insecticide treatment improved corn grain yield, reduced broken plants and increased stalk sugars content at harvesting, but did not change the rumen degradation of either stalks or grain.