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At least 19 recordsLinked to original sources
PubMed2002

Use of transgenic Bacillus thuringiensis Berliner corn hybrids to determine the direct economic impact of the European corn borer (Lepidoptera: Crambidae) on field corn in eastern Canada.

Transgenic corn expressing Bacillus thuringiensis Berliner (Bt corn) (Maximizer and Yieldgard hybrids, Novartis Seeds), non-Bt isolines and high-performance (check) hybrids were evaluated for European corn borer, Ostrinia nubilalis (Hübner), damage and grain yield in commercial strip plots across Ontario in 1996 and 1997. Bt corn hybrids reduced stalk tunneling damage by 88-100%. In 1996, minimal damage was found in locations where only one generation of European corn borer occurred per year. Bt corn proved its greatest potential for reducing the number and length of cavities below the primary ear in locations where two generations of European corn borer were present. A yield response to using Bt hybrids only occurred when levels of tunneling damage exceeded 6 cm in length. European corn borer infestations resulted in a 6 and 2.4% reduction in yield for 1996 and 1997, respectively, when Bt hybrids were compared with their non-Bt isolines. A linear relationship was found between tunnel length per plant in centimeters (x) and yield protection (%) obtained from using Bt corn (y) (y = 1.02 + 0.005x, r2 = 0.7217). At a premium of $34.58 Canadian (CDN) perhectare for Bt corn seed, an infestation of at least 6 cm of corn borer tunneling per plant was required to break even at a market price for corn of $2.50 per bushel CDN. During the period of study, low infestations (0-2 cm) of European corn borer occurred at 25% of the locations assessed, moderate infestations (4-6 cm) occurred at 42% of the locations, and high infestations (>6 cm) occurred at 33% of the locations. At a corn price of $3.00 per bushel CDN and seed premiums of $34.58 per hectare CDN, 5 cm of tunneling was required for a return on investment in Bt seed, comprising only 55% of the growers in the study. With infestations of more than 6 cm of tunneling occurring only 33% of the time, a return on seed investment would be realized in only one of three growing seasons. At a seed premium of $24.70 per hectare CDN per year, at least $74 per hectare CDN in the year of infestation would be required to make up for the two years of no return. In this study, a $74 per hectare CDN return at a corn price of $9.26 per hectare CDN with >16 cm of tunneling damage would have occurred only 7.3% of the time.

Animals↗
PubMed2004

Performance of growing-finishing pigs fed diets containing Roundup Ready corn (event nk603), a nontransgenic genetically similar corn, or conventional corn lines.

Two studies were conducted at two locations to evaluate growth performance and carcass characteristics of growing-finishing pigs fed diets containing either glyphosate-tolerant Roundup Ready (event nk603) corn, a nontransgenic genetically similar control corn (RX670), or two conventional sources of nontransgenic corn (RX740 and DK647). A randomized complete block design (three and four blocks in Studies 1 and 2, respectively) with a 2 x 4 factorial arrangement of treatments (two genders and four corn lines) was used. Study 1 used 72 barrows and 72 gilts (housed in single-gender groups of six; six pens per dietary treatment) with initial and final BW of approximately 22 and 116 kg, respectively. Study 2 used 80 barrows and 80 gilts (housed in single-gender groups of five; eight pens per dietary treatment) with initial and final BW of approximately 30 and 120 kg, respectively. Pigs were housed in a modified open-front building in Study 1 and in an environmentally controlled finishing building in Study 2. The test corns were included at a fixed proportion of the diet in both studies. Animals had ad libitum access to feed and water. Pigs were slaughtered using standard procedures and carcass measurements were taken. In Study 1, overall ADG, ADFI (as-fed basis), and gain:feed (G:F) were not affected (P > 0.05) by corn line. In Study 2, there was no effect of corn line on overall ADFI (as-fed basis) or G:F ratio. In addition, overall ADG of barrows fed the four corn lines did not differ (P > 0.05); however, overall ADG of gilts fed corn DK647 was greater (P < 0.05) than that of pigs fed the other corn lines. There was no effect (P > 0.05) of corn line on carcass yield or fatness measurements in either study. Differences between barrows and gilts for growth and carcass traits were generally similar for both studies and in line with previous research. Overall, these results indicate that Roundup Ready corn (nk603) gives equivalent animal performance to conventional corn for growing pigs.

Animal Feed↗
PubMed2004

Composition of grain and forage from corn rootworm-protected corn event MON 863 is equivalent to that of conventional corn (Zea mays l.).

Insect-protected corn hybrids containing event MON 863 protect corn plants against feeding damage from corn rootworm (Diabrotica), a major North American insect pest. Corn event MON 863 contains a gene that expresses an amino acid sequence variant of the wild-type Cry3Bb1 insecticidal protein from Bacillus thuringiensis. The purpose of this study was to compare the composition of corn containing event MON 863 with that of conventional nontransgenic corn. Compositional analyses were conducted to measure proximates, fiber, amino acids, fatty acids, minerals, folic acid, thiamin, riboflavin, vitamin E, antinutrients, and certain secondary metabolites in grain and proximates and fiber content in forage collected from a total of eight field sites in the U.S. and Argentina. Compositional analyses demonstrated that the grain and forage of event MON 863 are comparable in their nutritional content to the control corn hybrid and conventional corn. These comparisons, together with the history of the safe use of corn as a common component of animal feed and human food, support the conclusion that corn event MON 863 is compositionally equivalent to, and as safe and nutritious as, conventional corn hybrids grown commercially today.

Amino Acids↗
PubMed1987

Incidence of contamination with aflatoxin in precooked corn flour, corn grain and cracked corn.

A study was carried out to determine the presence and content of aflatoxins in 90 samples of precooked corn flour (23 yellow and 67 white), 40 samples of corn grain (30 yellow and 10 white), and 30 samples of yellow cracked corn. No aflatoxin was detected in white corn grain. The other investigated samples showed the following rates of contamination: yellow corn grain, 10%, ranging from less than 5 to greater than 10 ppb; yellow cracked corn, 16.6%, ranging from less than 5 to greater than 20 ppb; and white corn flour, 6%, and yellow corn flour, 87%. Of 14 aflatoxin positive samples tested, only 1 contained more than 20 ppb, the administrative guideline established by the US Food and Drug Administration (FDA). The results of this survey do not appear alarming because of the relatively low incidence and low levels of aflatoxin detected. However, since Venezuela is a big consumer of corn and corn-derived products, a more detailed investigation is suggested to establish the realistic levels of aflatoxin in these commodities.

Aflatoxins↗
PubMed2000

Glyphosate-tolerant corn: the composition and feeding value of grain from glyphosate-tolerant corn is equivalent to that of conventional corn (Zea mays L.).

Glyphosate-tolerant (Roundup Ready) corn line GA21 has been developed by genetic modification to tolerate glyphosate, the active ingredient in Roundup herbicide. The purpose of this study was to evaluate the compositional and nutritional safety of corn line GA21 compared to that of conventional corn. Compositional analyses were conducted to measure proximate, fiber, amino acid, fatty acid, and mineral contents of grain and proximate, fiber, and mineral contents of forage collected from 16 field sites over two growing seasons. The nutritional safety of corn line GA21 was evaluated in a poultry feeding study conducted with 2-day old, rapidly growing broiler chickens, at a dietary concentration of 50-60% w/w. Compositional analysis results showed that, except for a few minor differences that are unlikely to be of biological significance, the grain and forage of GA21 corn were comparable in their composition to that of the control corn line and to conventional corn. Results from the poultry feeding study showed that there were no differences in growth, feed efficiency, adjusted feed efficiency, and fat pad weights between chickens fed with GA21 grain or with parental control grain. These data taken together demonstrate that Roundup Ready corn is as safe and nutritious as conventional corn for food and feed use.

Amino Acids↗
PubMed1996

Fusaric acid and pathogenic interactions of corn and non-corn isolates of Fusarium moniliforme, a nonobligate pathogen of corn.

Fusarium moniliform is a nonobligate parasite of corn, which exists as a complex of closely related fungi from different mating population or biological species. Strains of this fungus isolated from corn, have been determined to belong to mating populations A, although other populations have been isolated from corn. The ultrastructural association of the fungus with corn during growth, and the effects of the host on suppression of disease suppression are reviewed. This fungus enters a relationship with corn cultivars that is not always pathogenic. Pathogenesis is delayed, if it ever occurs. F. moniliforme can exist entirely as an endophyte, systemically colonizing kernels, remaining there until germination upon which the fungus infects the emerging seedlings. The symptomless association persists during the growth cycle of corn, and the resulting endophytic hyphae may be the source of mycotoxin production. The host's ability to suppress the fungus appears to be related to one class of compounds, the cyclic hydroxamic acids and their decomposition products, which can be catabolized by the fungi of mating population A but not C.

Fusaric Acid↗
PubMed2004

Binomial sequential sampling plans for late instars of European corn borer (Lepidoptera: Crambidae), corn earworm (Lepidoptera: Noctuidae), and damaged kernels in sweet corn ears.

Late-season infestations of European corn borer, Ostrinia nubilalis (Hübner), and corn earworm, Helicoverpa zea (Boddie), were sampled to develop binomial sequential sampling plans for larval infestations and damaged kernels in sweet corn, Zea mays L., ears, near harvest. Fields were sampled to obtain a range of larval densities likely to be encountered over a range of infestation levels and field conditions. Binomial sampling plans were developed for O. nubilalis larvae, H. zea larvae, O. nubilalis, and H. zea larvae combined, and for damaged sweet corn kernels. Observed densities ranged from 0.01 to 4.40 larvae per ear for O. nubilalis, 0.005-1.62 larvae per ear for H. zea, and 0.004-36.12 damaged kernels per ear. Results of resampling analyses, based on the proportion of ears infested with one or more larvae, or damaged kernels, indicated an average sample size of 34-37 ears was necessary to classify whether larval infestations, or the incidence of damaged kernels, exceeded 5%. Two operating characteristic curves are presented for each of the four sampling plans. Initial results, with upper bounds of 0.10, and alpha (type I) and beta (type II) error rates at 0.10 and 0.05, respectively, resulted in a 90% probability of making the correct management decision at infestation levels >10%. To improve performance of the sampling plans, we modified the binomial plans by reducing the upper bound to 0.075, while maintaining the same error rates. This plan resulted in a higher probability (>95%) of making the correct management decision to reject a sweet corn load when infestation levels are >10%.

Animals↗
PubMed2002

Management of corn leafhopper (Homoptera: Cicadellidae) and corn stunt disease in sweet corn using reflective mulch.

Plastic reflective mulches significantly reduced populations of corn leafhopper, Dalbulus maidis (DeLong & Wolcott), adults and the incidence of corn stunt disease caused by Spiroplasma kunkelii (CSS) in late planted sweet corn (Zea mays L.). The reflective mulches were more effective than were either foliar or soil applied insecticides in managing both the leafhopper and the pathogen it transmits. Yields of marketable ears were 1.5 to 2 times greater in reflective mulch plots than from fallow plots. This was due to larger ears (individual ear weight and length) rather than an increase in the number of ears. The use of reflective mulches provides an alternative strategy to insecticides in the management of both D. maidis and corn stunt disease. Such a strategy may prove useful to growers in Latin America and to limited resource growers and organic growers in the United States who wish to grow corn without the use of insecticides.

Animals↗
PubMed2002

Biotechnology and the European corn borer: measuring historical farmer perceptions and adoption of transgenic Bt corn as a pest management strategy.

A 3-yr, multi-state survey of farmers who had planted transgenic Bacillus thuringiensis (Bt) corn was conducted to evaluate perceptions of Bt corn performance and its utility as a management option for European corn borer, Ostrinia nubilalis (Hübner). A questionnaire was sent to farmers in Illinois, Iowa, Kansas, Minnesota, Nebraska, and Pennsylvania who had grown Bt corn during the growing seasons of 1996, 1997, or 1998. There were 7,427 usable questionnaires returned with the following response percentages: 1996 (42.1%), 1997 (35.0%), and 1998 (22.6%). Adoption rates, based on percentage of acreage planted to Bt corn, increased dramatically from 1996 (10.5%) to 1998 (40.7%). The states growing the highest percentage of Bt corn were Minnesota, Iowa, and then Nebraska However, Illinois, was adopting Bt corn at the fastest rate. Historical use of insecticides did not influence the adoption of Bt corn. In addition, of those farmers who used insecticides to control European corn borer, the percentage that decreased their use of insecticides nearly doubled from 13.2% (1996) to 26.0% (1998) over this 3-yr period. The primary reason farmers planted Bt corn was to eliminate the yield loss caused by European corn borer. Scouting for European corn borers decreased from 91% (scouting 2.2 times a year) in 1996 to 75% (scouting 1.8 times a year) in 1998. The percentage of farmers not scouting for European corn borers increased from 9.6% (1996) to 25% (1998). Most farmers believed yields of Bt hybrids were either similar to or greater than the yields of non-Bt hybrids. Minnesota farmers perceived the greatest yield advantages. Farmers are becoming more aware of insect resistance management guidelines; however, they also clearly show preferences for having the flexibility to use different spatial plantings of Bt and non-Bt corn. Finally, after having planted Bt corn and obtained excellent control of European corn borer, most farmers believed that this insect had been causing more yield loss than they previously had suspected in their non-Bt corn. The data represented here provide an historical foundation for how transgenic Bt corn was used by farmers during the first 3 yr of commercial availability, their initial perceptions on the performance of this technology, and their attitudes regarding management of the European corn borer.

Animals↗
PubMed2003

Transgenic Bacillus thuringiensis corn hybrid performance against univoltine ecotype European corn borer (Lepidoptera: Crambidae) in South Dakota.

The performances of Bt-corn hybrids against univoltine ecotype European corn borer larvae were evaluated in South Dakota from 1997 to 1999. The corn hybrids were exposed to natural seasonal fluctuations of a univoltine ecotype European corn borer population. Larval injury parameters, grain yields, and gross incomes were quantified during the 3-yr study. In general, the Bt-corn hybrids had significantly higher yields than the untreated non-Bt isolines in 1997 and 1998 when corn borer pressures were high. However, most of the Bt-corn hybrids did not produce significant yield advantages in 1999 when the European corn borer pressure was low. Some of the Bt-corn hybrids even produced significantly lower yields than their untreated non-Bt counterparts in 1999. The performances of non-Bt isolines that were treated with permethrin granules at whorl stage were similar to Bt-corn hybrids in 1998 when the corn borer pressure was high and similar to the untreated non-Bt isolines in 1999 when the corn borer pressure was low. Injury-free corn produced by Bt-corn hybrids did not necessarily translate into higher yields in some hybrid groups. Grain moisture at harvest, which can result in moisture penalty or dockage, was significantly higher in most Bt-corn hybrids. Gross incomes of the Bt-corn hybrids were generally higher than the untreated non-Bt isolines when the corn borer infestation was high, but were either similar to or lower than the untreated non-Bt isolines when the corn borer infestation was low.

Animals↗
PubMed2004

Effects of concentration and composition of wet corn gluten feed in steam-flaked corn-based finishing diets.

Two finishing experiments were conducted to determine the effects of concentration (Exp. 1) and composition of wet corn gluten feed (Exp. 2) in steam-flaked corn-based diets on feedlot steer performance. In Exp. 1, 192 English x Continental crossbred steer calves (299 +/- 0.6 kg) were used in a completely randomized design with six dietary treatments (four pens per treatment). Treatments were six concentrations of wet corn gluten feed (Sweet Bran, Cargill Inc., Blair, NE; 0, 10, 20, 25, 30, and 35%) replacing steam-flaked corn (DM basis). All diets contained 10% corn silage, 5% supplement, and 3.5% tallow (DM basis). Gain efficiency and ADG were similar (P > 0.25) among treatments. Dry matter intake was lower (P < 0.10) with 0% wet corn gluten feed than with concentrations of 20, 25, and 35% WCGF. Dry matter intake did not differ among treatments containing wet corn gluten feed. In Exp. 2, 160 English x Continental crossbred steer calves (315 +/- 0.6 kg) were used in a completely randomized design with five dietary treatments (four pens/treatment). Treatments were assigned based on four ratios of steep to corn bran/germ meal mix in wet corn gluten feed plus a negative control (CON). Wet corn gluten feed was fed at 25% of the dietary DM and was made by mixing steep and corn bran/germ meal into the diet. The four concentrations of steep in wet corn gluten feed that comprised the ratios were 37.5, 41.7, 45.8, and 50% (DM basis), with the remaining proportion being the bran/germ meal mix. Bran/germ meal mix was comprised of 60% dry corn bran, 24% germ meal, and 16% fine-cracked corn (DM basis). All diets contained 10% corn silage, 5% supplement, and 3.5% tallow (DM basis). Daily gain did not differ (P = 0.18) among treatments. Gain efficiency did not differ between CON and 50% steep; however, G:F was decreased (P < 0.05) for concentrations of 37.5, 41.7, and 45.8% steep compared with CON. A linear improvement (P < 0.05) was observed for G:F as concentration of steep increased as a proportion of wet corn gluten feed. These data suggest that wet corn gluten feed can be used at concentrations up to 35% of the dietary DM without adversely affecting performance, and that steep has more energy than bran/germ meal in steam-flaked corn-based diets.

Animal Feed↗
PubMed2000

Pathogens associated with southwestern corn borers and southern corn stalk borers (Lepidoptera: Crambidae).

A study was undertaken to isolate entomopathogens of southwestern corn borer, Diatraea grandiosella Dyer, and southern corn stalk borer, Diatraea crambidoides (Grote). Field-collected diapausing larvae of southwestern corn borer (three sites in Mississippi) and southern corn stalk borer (one site in North Carolina), and a laboratory strain of D. grandiosella in the diapause state were maintained in a simulated winter followed by a simulated spring environnent. Few larvae (< or = 6%) collected from any of the field sites died in the winter environment, and most insect mortality (11-25%) occurred after transfer of the larvae to the simulated spring environment. Mortality during the simulated spring period differed among the collection sites, and the highest mortality was recorded for southwestern corn borers from Washington County (25%), followed by Marshall (16%) and Oktibbeha (11%) Counties. A high level of mortality was also observed in southern corn stalk borers during the simulated spring period (27%). No viruses were observed, but a number of bacteria, microsporidia, and fungi were isolated from both southwestern corn borer and southern corn stalk borer larvae and pupae. In most instances, numerous bacterial taxa were isolated from cadavers, but on some occasions a single taxon predominated. The most prevalent bacterial taxon from larval and pupal cadavers was Enterococcus faecalis (Andrewes & Horder) Schleifer & Kilppel-Balz, but Bacillus spp., Pseudomonas aeruginosa (Schroeter) Migula, and Serratia marcescens Bizio were frequently isolated as well. Few fungi (1-7%) were recovered from southwestern corn borer and southern corn stalk borer larvae and pupae. The most common entomopathogenic taxon isolated was Beauveria bassiana (Balsamo) Vuillemin from southern corn stalk borer larvae. Microsporidia were not isolated from southern corn stalk borers. However, Nosema spp. were isolated from southwestern corn borer cadavers from Washington (15%), Marshall (1%), and Oktibbeha (3%) Counties in Mississippi. In addition, we observed parasitism of southern corn stalk borer larvae by Macrocentrus cingulum Reinhard (Hymenoptera: Braconidae). No parasitism of southwestern corn borers was observed. Isolates of Bacillus, Beauveria, Entercoccus, Nosema, Pseudomonas and Serratia were all pathogenic to southwestern corn borer larvae under controlled environmental conditions, and with the exception of B. bassiana, these are novel pathogens of Diatraea corn borers.

Animals↗
PubMed2004

Effects of dry, wet, and rehydrated corn bran and corn processing method in beef finishing diets.

Two finishing trials were conducted to determine the effects of adding different types of corn bran, a component of corn gluten feed, on cattle performance. In Trial 1, 60 English crossbred yearling steers (283 +/- 6.7 kg) were used in a completely randomized design with four dietary treatments. Treatments were diets with no corn bran, dry corn bran (86% DM), wet corn bran (37% DM), and rehydrated dry bran (37% DM). Bran was fed at 40% of dietary DM. All finishing diets had (DM basis) 9% corn steep liquor with distillers solubles, 7.5% alfalfa hay, 3% tallow, and 5% supplement. Gain efficiency and ADG were greater (P < 0.01) for cattle fed no corn bran compared with all treatments containing corn bran; however, no differences were detected across corn bran types. In Trial 2, 340 English crossbred yearling steers (354 +/- 0.6 kg) were used in a randomized block design with treatments assigned based on a 2 x 4 + 2 factorial arrangement (four pens per treatment). One factor was the corn processing method used (dry-rolled corn, DRC; or steam-flaked corn, SFC). The other factor was corn bran type: dry (90% DM), wet (40% DM), or dry bran rehydrated to 40 or 60% DM. Bran was fed at 30% of dietary DM, replacing either DRC or SFC. Two control diets (DRC and SFC) were fed with no added bran. All finishing diets contained (DM basis) 10% corn steep liquor with distiller's solubles, 3.5% alfalfa hay, 3.5% sorghum silage, and 5% supplement. Corn bran type did not affect DMI (P = 0.61), ADG (P = 0.53), or G:F (P = 0.10). Dry matter intake was greater (P < 0.01) by steers fed bran compared with those fed no bran, and was greater by steers fed DRC than by steers fed SFC (P < 0.01). Interactions occurred (P < 0.01) between grain source and bran inclusion for ADG and G:F. The ADG by steers fed the SFC diet without bran was greater (P < 0.01) than by steers fed SFC diets with bran, whereas the ADG by steers fed DRC diets with or without bran was similar. Daily gain was 15.2% greater (P < 0.01) by steers fed SFC without bran than by steers fed DRC without bran. Gain efficiency was 16.9% greater (P < 0.01) for steers fed SFC without bran compared with steers fed DRC without bran. In DRC and SFC diets, feeding bran decreased (P < 0.01) G:F by 5.2 and 13.8%, respectively. The moisture content of corn bran had no effect on finishing steer performance, and drying corn bran did not affect its energy value in finishing cattle diets.

Animal Feed↗
PubMed1999

Evaluation of transgenic sweet corn hybrids expressing CryIA (b) toxin for resistance to corn earworm and fall armyworm (Lepidoptera: Noctuidae).

Many of the lepidopterous insects which attack sweet corn, Zea mays L., are susceptible to insecticidal proteins produced by Bacillus thuringiensis ssp. kurstaki (Berliner) (Btk). Transgenic sweet corn expressing a synthetic cry gene for production of a Btk-insecticidal protein may provide a more environmentally acceptable means of sweet corn production. Eight transgenic sweet corn hybrids containing a synthetic gene for CryIA(b) protein production (BT11 event) were evaluated for resistance to the corn earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J. E. Smith). Laboratory tests revealed that all Btk sweet corn hybrids were highly resistant to leaf and silk feeding by neonate 3 and 6 d old corn earworm larvae. Ear damage in the field to the Btk sweet corn hybrids caused by corn earworm was negligible. All Btk sweet corn hybrids, except Btk 95-0901, were moderately resistant to leaf and silk feeding by the fall armyworm. Survival and weight gain were reduced when neonates were fed excised whorl leaves of the Btk plants. Weight gain, but not survival, was reduced when 3- and 6-d-old fall armyworm larvae were fed excised whorl leaves of the Btk plants. Btk sweet corn hybrids appear to be ideal candidates for use in integrated pest management (IPM) programs for both the fresh and processing sweet corn markets, and their use should drastically reduce the quantity of insecticides currently used to control these pests in sweet corn. With appropriate cultural practices, it is highly unlikely that Btk sweet corn will contribute to the development of resistance to Btk proteins in these insects because of the high toxicity of the Cry proteins expressed in these sweet corn hybrids and the harvest of sweet corn ears from fields before larvae can complete development.

Animals↗
PubMed2002

Utilization of Bt corn residues by grazing beef steers and Bt corn silage and grain by growing beef cattle and lactating dairy cows.

Three experiments were conducted to evaluate the impact of the Bacillus thuringiensis (Bt)-11 transformation event in two parental corn hybrids differing in date of maturity on beef and dairy cattle performance. Sixteen lactating Holstein dairy cows in replicated 4 x 4 Latin squares were assigned to four diets in a 2 x 2 factorial arrangement: Bt vs non-Bt trait and early- vs late-maturing corn hybrids. The diets contained 40% of the test corn silage plus 28% corn grain from the same corn hybrid (DM basis). There was no effect of the Bt trait on efficiency of milk production, ruminal pH, acetate:propionate ratio, or in situ digestion kinetics of NDF. The early-maturing corn hybrids resulted in greater total VFA concentrations in the rumen and efficiency of 4% fat-corrected milk production than the later-maturing hybrids (P < 0.05). Sixty-seven steer calves were used in a 70-d corn residue grazing trial for the late-maturing corn hybrids only. Daily BW gain of steers was similar for those grazing Bt and non-Bt corn residues, and the steers exhibited no grazing preference between Bt and non-Bt corn residue. One hundred twenty-eight steer calves were assigned to four silage-based growing diets in a 2 x 2 factorial arrangement: Bt vs non-Bt trait and early- vs late-maturing corn hybrids. The diets contained 90% corn silage and 10% supplement (DM basis). The DMI was higher for steers fed Bt compared with non-Bt hybrids (P < 0.02). An interaction (P < 0.03) was observed for feed efficiency between hybrid genotype and incorporation of the Bt trait. Feed efficiency was greater (P < 0.05) for steers fed the later-maturing non-Bt hybrid compared with the later-maturing Bt hybrid; however, feed efficiency was similar between steers fed early-maturing Bt and non-Bt corn silages. Steers fed the early-maturing hybrid gained 11% faster and were 7% more efficient compared with those fed the late-maturing hybrid. These latter results agree with the dairy experiment in which the early-maturing hybrid resulted in 5% greater efficiency of milk production than the later-maturing corn hybrid. In all experiments, incorporation of the Bt trait into corn had no consistent effect on cattle performance. In addition, background genetics of the corn hybrids appeared to have a more consistent impact on performance than did presence of the Bt trait.

Animal Feed↗
PubMed2003

Economic analysis of planting dates to manage European corn borer (Lepidoptera: Crambidae) with Bt corn.

Planting dates of transgenic Bacillus thuringiensis Berliner (Bt) corn were adjusted to determine the utility in managing European corn borer, Ostrinia nubilalis (Hübner). Transgenic Bt (events 176 and Bt11) corn and non-Bt corn were planted at three different times to use the early- and late- planted corn as a potential trap crop for ovipositing European corn borer moths. Grain moisture and yields were recorded to determine the economic benefits of Bt corn planted on the different dates, based on European corn borer populations and corn damage data collected before harvest. Data were recorded from three locations in southwestern, central, and northeastern Iowa for three summers (1996-1998). Economic benefits are discussed in relation to EILs and yield results. Adjusting the planting dates of Bt and non-Bt corn provided variable economic differences among planting dates in northern Iowa; however, greater economic benefits were realized when Bt corn was planted late during the planting sequence in central and southwestern Iowa. These results suggest that planting corn should be conducted in a timely manner and, if delayed or required to plant late, planting Bt corn would likely provide greater economic benefits. Although yield and economic variability were high, using Bt corn in combination with planting date adjustments may be a viable option for managing European corn borer.

Animals↗
PubMed2002

Effect of high-oil corn or added corn oil on ruminal biohydrogenation of fatty acids and conjugated linoleic acid formation in beef steers fed finishing diets.

Three Angus steers (410 kg) cannulated in the proximal duodenum were used in a replicated 3 x 3 Latin square to evaluate the effects of dietary lipid level and oil source on ruminal biohydrogenation and conjugated linoleic acid (CLA) outflow. Dietary treatments included: 1) typical corn (TC; 79.2% typical corn), 2) high-oil corn (HOC; 79.2% high-oil corn), and 3) the TC diet with corn oil added to supply an amount of lipid equal to the HOC diet (OIL; 76.9% TC + 2.4% corn oil). Duodenal samples were collected for 4 d following 10-d diet adaptation periods. Data were analyzed with animal, square, period, and treatment in the model and planned, nonorthogonal contrasts were used to test the effects of dietary lipid content (TC vs HOC and OIL) and oil source (HOC vs OIL) on ruminal biohydrogenation. Intake and duodenal flow of total long-chain fatty acids were increased (P < 0.05) by over 63% for diets containing more lipid regardless of oil source. Apparent ruminal dry matter and long chain fatty acid digestibilities were not altered (P > 0.05) by dietary lipid level or oil source. Ruminal biohydrogenation of total and individual 18-carbon unsaturated fatty acids was greater (P < 0.05) for diets with higher lipid content. Biohydrogenation of oleic acid was greater (P < 0.05) for HOC than OIL, but biohydrogenation of linoleic acid was lower (P < 0.05) for HOC than OIL. Duodenal flows of palmitic, stearic, oleic, linoleic, and arachidic acids were more than 30% greater (P < 0.05) for diets containing more lipid. Flow of all trans-octadecenoic acids was greater (P < 0.05) for diets containing more lipid. Corn oil addition increased (P < 0.05) the flow of trans-10 octadecenoic acid and the trans-10, cis-12 isomer of CLA by threefold compared to feeding high-oil corn. Feeding high-oil corn or adding corn oil to typical corn rations increased intake, biohydrogenation, and duodenal flow of unsaturated long-chain fatty acids. Compared with high-oil corn diets, addition of corn oil increased duodenal flow of trans-10, trans-12 and cis-12 isomers of octadecenoic acid and the trans-10, cis-12 isomer of CLA. The amount of cis-9, trans-11 isomer of conjugated linoleic acid flowing to the duodenum was less than 260 mg/d, a value over 20 times lower than flow of trans-11 vaccenic acid indicating the importance of tissue desaturation for enhanced conjugated linoleic acid content of beef.

Animals↗
PubMed2002

Survival of kansas dipel-resistant European corn borer (Lepidoptera: Crambidae) on Bt and non-Bt corn hybrids.

The Kansas Dipel-resistant and susceptible European corn borer, Ostrinia nubilalis (Hübner), were evaluated in the greenhouse on different Bt transgenic events expressed in corn hybrids. There were important differences in the resistance offered by the different Bt event corn hybrids. Hybrid comparison tests indicate that these Dipel-resistant first-instar European corn borer were not able to survive to adulthood on whorl-stage MON810, Bt11, or 176 Bt event corn plants. Third instars did not survive to adulthood on whorl-stage MON810 or Bt11 event corn plants but a small number of fifth instars were found on whorl-stage DBT418 plants infested with Dipel-resistant larvae. First and third instars of these Dipel-resistant European corn borers caused more leaf-feeding damage and more tunneling on whorl-stage Bt-corn plants than did the Dipel-susceptible European corn borers. However, in the single Bt corn hybrid test, there was no survival of the Dipel-resistant European corn borers on DK580BtX or MAX454 Bt plants 35 to 42 d after they had been infested with first instars. These results demonstrate that the current Kansas selection of Dipel-resistant European corn borer strain cannot establish reproducing populations in the tested Bt corn lines and hybrids.

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