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PubMed2003

Efficacy of high available phosphorus corn in laying hen diets.

Our objective was to determine if high available phosphorus corn would provide sufficient available phosphorus (AP) to laying hens fed corn-soybean meal diets from 57 to 69 wk of age. Six replications of 12 Dekalb Sigma Leghorn hens were fed a normal yellow dent (YD) corn-soybean meal diet or high available phosphorus (HAP) corn-soybean meal diet without and with 0.04% supplemental inorganic P. The unsupplemented YD diet was calculated to contain 17% CP, 3.8% Ca, and 0.10% AP, and the unsupplemented HAP diet contained 17% CP, 3.8% Ca, and 0.16% AP. In addition, a positive control, YD diet (17% CP, 3.8% Ca, 0.45% AP) was also fed. The HAP corn was directly substituted for YD on a weight basis, and the amount of soybean meal was kept constant in all diets. Egg production, hen body weight, egg weight, egg mass, feed consumption, and feed efficiency were measured. The YD and the YD + 0.04% P treatments were terminated at 61 and 65 wk of age, respectively, due to severe depressions in egg production. Egg production and egg mass for hens fed HAP diets were not different (P > 0.05) from those of hens fed the 0.45% AP diet; however, hens fed the unsupplemented HAP diet did have lower hen body weights and feed intake (P < 0.05) compared to hens fed the positive control diet. Our results indicate that HAP corn contains more available P than normal YD corn and that hens can be fed HAP corn-soybean meal diets containing little or no P supplementation with only minimal effects on production performance.

Animal Feed↗

PubMed1982

Protein utilisation in response to caecal corn starch in ponies.

The influence of administering caecal corn starch (0.0, 0.2, 0.4 or 0.6 g/kg body weight/day) on protein utilisation in 4 ponies was analysed with a latin square experimental design. The basal diet was dehydrated alfalfa pellets. Determinations were made of nitrogen retention, protein and dry matter digestions, total plasma protein, plasma urea nitrogen, plasma ammonia and plasma-free amino acids. Twice daily administration of corn starch into the caecum resulted in an increased nitrogen retention (P less than 0.01). Maximum nitrogen retention was observed with the caecal administration of 0.4 g/kg bwt of corn starch/day. Nitrogen retention expressed as percentage of the nitrogen absorbed was significantly higher (P less than 0.01) when corn starch was caecally administered. Digestion coefficients for dry matter and protein tended to be higher in ponies receiving the corn starch. Values of blood urea nitrogen in ponies administered the 0.0, 0.2, 0.4 or 0.6 g levels were 7.74, 6.47, 5.36 and 7.39 mmol/litre, respectively. Total plasma protein concentration was not changed by treatment. A lower plasma ammonia level was observed at the 0.4 g/kg bwt treatment level when corn starch was administered via the caecum. A trend toward an increase in plasma essential amino acid concentrations of isoleucine, phenylalanine, leucine, arginine and threonine were observed with ponies receiving caecal corn starch. Likewise, non-essential amino acid concentrations of tyrosine, serine, proline and glycine were also elevated. A slight increase in glycine concentration was observed at the 0.2 g/kg bwt treatment level. These results suggest that the administration of corn starch into the caecum resulted in more efficient utilisation of nitrogen by the large intestine.

Amino Acids↗

PubMed2000

Foraging resources of adult Mexican corn rootworm (Coleoptera: Chrysomelidae) in Bell County, Texas.

Pollen analyses were used to determine pollen foraging resources of adult Mexican corn rootworms, Diabrotica virgifera zeae Krysan & Smith, captured near Temple, Bell County, TX, in 1996 and 1997. In 1996, adult Mexican corn rootworms were captured in a corn, Zea mays L., field. In 1997, nine locations outside of cornfields were added. Overall, 92% of the beetles (n = 1,323) contained pollen. More than 142,000 pollen grains were counted, representing 45 families, 63 genera, and 27 species. Overall, in 1996, noncorn grass pollen (70%) occurred in the greatest percentage of total pollen followed by corn (17%), then nongrass pollen (13%). In 1997, noncorn grass pollen (76%) had the greatest percentage, then nongrass (18%), and finally corn pollen (6%). Corn pollen was found in 34% of the beetles in 1996 and 26% in 1997. Fifteen Asteraceae taxa were encountered including sunflower, Helianthus annuus L. Thirteen Fabaceae were found including soybean, Glycine max L. Mexican corn rootworm adults foraged mainly on noncorn grass pollen, but also foraged on pollen from a large diversity of plant species, indicating that noncorn pollen may play a role in the food habits of Mexican corn rootworm adults.

Animals↗

PubMed2001

Response of potato tuber yield to stem injury by European corn borer (Lepidoptera: Crambidae) in the Mid-Atlantic United States.

The response of potato, Solanum tuberosum L., tuber yield to stem injury by European corn borer, Ostrinia nubilalis (Hübner), larvae was investigated in the Mid-Atlantic region of the United States for 3 yr. This response was described for 'Superior', 'Atlantic', and 'Snowden' potato, which are early-season, midseason, and late-season maturing cultivars, respectively. To model the yield/injury relationship, a range of corn borer injury levels was established in the field by augmenting the natural infestation with varying densities of laboratory-reared larvae. Linear and nonlinear regression analyses (plateau and second-order polynomial models) were used to describe the relationship between yield of U.S. No. 1 grade tubers and the percentage of stems injured by corn borer larvae. The maturity of the cultivar did not affect the response of potato yield to stem injury. In nine of 14 experiments, potato tolerated high levels of corn borer injury (55-90% of stems injured) without yield loss, suggesting that control of corn borer may not be necessary. Yet, in one of five Superior tests, in two of four Atlantic tests and in two of five Snowden tests, corn borer injury significantly reduced yield. Of the five data sets in which corn borer injury reduced yield, the plateau model fit two data sets and the quadratic model fit one data set. In two of the three cases, these models accounted for nearly identical amounts of total variation in yield as that accounted for by the linear model. The linear model fit four of the five data sets, but the R2 values were low for three of the four tests (0.10, 0.18, and 0.31). The parameter or parameters that interact with corn borer injury to cause tuber yield reduction should be identified before economic injury levels and thresholds are developed.

Animals↗

PubMed2002

Southwestern corn borer (Lepidoptera: Crambidae) damage and aflatoxin accumulation in maize.

Aflatoxin, a potent carcinogen, is produced by the fungus Aspergillus flavus Link: Fr. Drought, high temperatures, and insect damage contribute to increased levels of aflatoxin contamination in corn, Zea mays L. Plant resistance is widely considered a desirable method of reducing aflatoxin contamination. Germplasm lines with aflatoxin resistance have been developed. This investigation was undertaken to determine whether crosses among these lines exhibited resistance to southwestern corn borer, Diatraea grandiosella Dyar, and to assess the effects of southwestern corn borer feeding on aflatoxin accumulation. Differences in ear damage among southwestern corn borer infested hybrids were significant. Estimates of general combining ability effects indicated that the lines Mp80:04, Mp420, and Mp488 contributed to reduced ear damage, and SC213 and T165 contributed to greater damage when used in hybrids. Mean aflatoxin levels were 254 ng/g for hybrids infested with southwestern corn borer larvae and 164 ng/g for noninfested hybrids in 2000 when environmental conditions were conducive to aflatoxin production. In contrast, the overall mean aflatoxin level for southwestern corn borer infested hybrids was only 5 ng/g in 1999 when environmental conditions did not favor aflatoxin accumulation. Crosses that included lines selected for aflatoxin resistance as parents (Mp80:04 and Mp313E) exhibited lower levels of aflatoxin contamination both with and without southwestern corn borer infestation in 2000. Only the experimental line Mp80:04 contributed significantly to both reduced southwestern corn borer damage and reduced aflatoxin contamination.

Aflatoxins↗

PubMedDate not supplied

Phosphorus leaching under a restored tallgrass prairie and corn agroecosystems.

Most studies of phosphorus (P) movement in soil have based their conclusions on patterns of extractable soil P as a function of depth, which has led to the assumption that no substantial leaching loss occurs because of high P-fixation capacity in mineral soils. Few studies have involved high-quality leachate samples collected below the root zone; rather, most have involved tile drainage systems. Equilibrium-tension lysimeters installed at a depth of 1.4 m were used to evaluate and compare P leaching from a restored tallgrass prairie and corn (Zea mays L.) agroecosystems on Plano silt loam soil (fine-silty, mixed, superactive, mesic Typic Argiudoll) in southcentral Wisconsin during a 5-yr period. The corn agroecosystem treatments included nitrogen (N)-fertilized (f) or N-unfertilized (nf) and no-tillage (NT) or chisel-plowed (CP). Mean volume-weighted molybdate-reactive phosphorus (MRP) and total dissolved phosphorus (TDP) concentrations were similar within replicate samples, but always higher in NTf corn than in the prairie or CPf corn systems, though drainage from the CPf corn was always higher than from the NTf corn system. Water-extractable soil P concentrations at any given depth were not positively correlated with leachate concentrations, suggesting that macropore flow causes infiltrating runoff to preferentially bypass the bulk of the soil matrix. Leachate-P concentrations from the natural and managed agroecosystems exceeded 0.01 mg P L(-1) and leaching losses were significantly higher from N-fertilized corn, regardless of tillage, than from the prairie or N-unfertilized corn systems, from which leachate-P concentrations and loads were similar. Increased root growth from N fertilization could cause more macropore formation, preferential flow, and P mineralization from decaying roots compared with N-unfertilized systems, which could contribute to a N-fertilization effect on P leaching.

Agriculture↗

PubMedDate not supplied

Cover cropping to reduce nitrate loss through subsurface drainage in the northern U.S. corn belt.

Despite the use of best management practices for nitrogen (N) application rate and timing, significant losses of nitrate nitrogen (NO3(-)-N) in drainage discharge continue to occur from row crop cropping systems. Our objective was to determine whether a autumn-seeded winter rye (Secale cereale L.) cover crop following corn (Zea mays L.) would reduce NO3(-)-N losses through subsurface tile drainage in a corn-soybean [Glycine mar (L.) Merr.] cropping system in the northern Corn Belt (USA) in a moderately well-drained soil. Both phases of the corn-soybean rotation, with and without the winter rye cover crop following corn, were established in 1998 in a Normania clay loam (fine-loamy, mixed, mesic Aquic Haplustoll) soil at Lamberton, MN. Cover cropping did not affect subsequent soybean yield, but reduced drainage discharge, flow-weighted mean nitrate concentration (FWMNC), and NO3(-)-N loss relative to winter fallow, although the magnitude of the effect varied considerably with annual precipitation. Three-year average drainage discharge was lower with a winter rye cover crop than without (p = 0.06). Over three years, subsurface tile-drainage discharge was reduced 11% and NO3(-)-N loss was reduced 13% for a corn-soybean cropping system with a rye cover crop following corn than with no rye cover crop. We estimate that establishment of a winter rye cover crop after corn will be successful in one of four years in southwestern Minnesota. Cover cropping with rye has the potential to be an effective management tool for reducing NO3(-)-N loss from subsurface drainage discharge despite challenges to establishment and spring growth in the north-central USA.

Agriculture↗

PubMed1993

Microbially detoxified vomitoxin-contaminated corn for young pigs.

A performance trial was conducted to evaluate the effect of microbially detoxified moldy corn in a corn-soybean meal-based starter diet for young pigs. Moldy corn containing 450 ppm of vomitoxin replaced clean corn in a control diet to give a diet containing 5 ppm of vomitoxin. The same amount of moldy corn was microbially detoxified by incubation with the contents of the large intestine of chickens (CLIC) and then incorporated into the control diet to give a "detoxified" vomitoxin diet, which contained 2.1 ppm of vomitoxin. A paired diet was formulated by incorporating the untreated moldy corn into the control diet to give a diet containing the same level of vomitoxin as the "detoxified" vomitoxin diet. Clean corn was also treated with CLIC and replaced corn in the control diet to give a biologically treated control diet. Each diet was fed to six pigs (three gilts and three boars) for 5 d and then all pigs were changed to the control diet for a further 5-d feeding period. During the first 5-d feeding period, no differences were observed in pigs fed either the control diet or the biologically treated control diet. A diet containing 5 ppm of vomitoxin decreased the pigs' daily feed consumption, weight gain, and feed efficiency by 25, 57, and 45%, respectively, compared with the control diet (P < or = .05). Daily feed intake, weight gain, and feed efficiency in pigs fed the "detoxified" vomitoxin diet were 19, 54, and 37% greater, respectively, than for pigs fed the vomitoxin diet (P < or = .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1993

Effects of increasing levels of corn or beet pulp on utilization of low-quality crested wheatgrass hay by lambs and in vitro dry matter disappearance of forages.

Two trials were conducted to evaluate the effects of corn or dried beet pulp on intake and digestibility of forage by lambs and on IVDMD. In Trial 1, 16 lambs (average BW = 41 +/- .9 kg) were used in a randomized complete block design with eight lambs per block. Lambs were fed a crested wheatgrass hay (7.5% CP) and received either no supplement (NS), a protein supplement (PS), or protein supplements with various levels of corn or beet pulp. Corn supplements supplied 1.75 (PCL), 3.5 (PMC), and 5.25 (PHC) g of corn/kg of BW, whereas beet pulp supplements supplied 2.1 (PLBP), 4.2 (PMBP), and 6.3 (PHBP) g of beet pulp/kg of BW. All supplemented lambs received .128 g of CP/kg of BW. Hay DMI decreased linearly (P < .03) as the level of corn and beet pulp increased in the supplement. Total DMI decreased linearly (P = .013) as the level of corn increased; however, beet pulp did not affect total DMI (P > .71). Supplemental corn increased (P = .03) apparent diet DM digestibility (DMD), whereas supplemental beet pulp did not affect (P > .32) diet DMD. Lambs whose diet was supplemented with beet pulp had greater (P = .010) estimated hay DMD than lambs whose diet was supplemented with corn. In Trial 2, 48-h IVDMD was determined on each of three forages mixed with either corn or beet pulp. The crude protein content of the three forages was 4.9, 9.4, and 12.2% for low-, medium-, and high-quality forages, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1998

The influence of processed corn and supplemental fat on digestion of limit-fed diets and performance of beef cows.

Trial 1, 135 crossbred cows with calves were used to compare limit-fed corn-hay diets with ad libitum hay and cracked with whole corn in limit-fed diets. Diets were to supply similar TDN intakes. Cow-calf pairs were fed treatment diets from 24 h after parturition until the beginning of the breeding season (62+/-13 d). Cow and calf performance was not affected (P > .05) by intake level or corn processing. In Trial 2, 48 crossbred primiparous cows with calves were used to determine the effect of adding 4% fat to a limit-fed corn-hay diet. Diets were to provide similar TDN intakes. Cow-calf pairs were fed treatment diets from 24 h after parturition until the breeding season started (79+/-14 d). Cow weight, condition score change, and calf gain were not affected (P > .05) by supplemental fat. Milk yield and composition were not different (P > .05) 52 d postpartum. At 92 d postpartum, milk production was 65% greater (P = .01) for cows that received supplemental fat. In Trial 3, four cannulated steers were used to evaluate the influence of corn processing and fat supplementation on digestion. Feeding cracked corn improved (P < .05) DM and OM digestion compared with whole corn. Adding 4% supplemental fat did not influence (P > .05) digestion. Limit-feeding a corn-hay diet is an alternative to feeding ad libitum hay that can accomplish similar cow and calf performance. Supplementation of 4% fat can be used in a limit-fed diet without detrimental effects on digestion, lactation, or cow and calf performance.

Animals↗

PubMed1999

Limit-feeding corn as an alternative to hay reduces manure and nutrient output by Holstein cows.

Efficiency of limit-feeding a whole shelled corn-based diet as an alternative to a conventional forage-based diet for nonlactating dairy cattle was determined. Twelve nonlactating, multiparous Holstein cows (initial BW 642+/-50 kg) were used in a randomized complete block design. Nutrient digestibility, excretion of DM, N, and P, performance of cows, and feed costs were measured. Both diets were formulated to provide equal daily intakes of NE1, protein, vitamins, and minerals, according to National Research Council recommendations. Dry matter intake was restricted by 30% for cows fed the high-corn diet compared with the high-forage diet (6.8 vs 9.6 kg/ d, respectively); therefore, concentrations of nutrients in the high-corn diet were increased to compensate for decreased DMI. Diets were fed once daily, and cows had unlimited access to fresh water. After a 28-d adaptation period, cows were placed in metabolism stalls for a 6-d total collection of feces and urine. The limit-fed, high-corn diet had a 15% greater DM digestibility than the high-forage diet. A 29% decrease in DMI for the high-corn diet vs the high-forage diet resulted in a 40% decrease in fecal DM excretion. Starch digestibility and digestibility of whole corn kernels were not affected (P > or = .62) by diet. Despite similar N intakes, total N excretion was 22% greater (P < .01) for cows fed the high-forage diet than for those limit-fed the high-grain diet. Cow weight and condition score change did not differ (P > .10) between diets. Feed costs were reduced by $.38/d with the high-corn diet vs the high-forage diet. Limit-feeding a corn-based diet is an economically and nutritionally viable alternative to forage-based diets for nonlactating Holstein cows.

Animal Feed↗

PubMed2001

Supplemental soybean oil or corn for beef heifers grazing summer pasture: effects on forage intake, ruminal fermentation, and site and extent of digestion.

Nine Angus x Gelbvieh heifers (average BW = 347 +/- 2.8 kg) with ruminal and duodenal cannulas were used in a split-plot designed experiment to determine the effects of soybean oil or corn supplementation on intake, OM, NDF, and N digestibility. Beginning June 8, 1998, heifers continually grazed a 6.5-ha predominantly bromegrass pasture and received one of three treatments: no supplementation (Control); daily supplementation of cracked corn (Corn) at 0.345% of BW; or daily supplementation (0.3% of BW) of a supplement containing cracked corn, corn gluten meal, and soybean oil (12.5% of supplemental DM; Oil). Soybean oil replaced corn on a TDN basis and corn gluten meal was included to provide equal quantities of supplemental TDN and N. Three 23-d periods consisted of 14 d of adaptation followed by 9 d of sample collections. Treatment and sampling period effects were evaluated using orthogonal contrasts. Other than crude fat being greater (P = 0.01) for supplemented heifers, chemical and nutrient composition of masticate samples collected via ruminal evacuation did not differ (P = 0.23 to 0.56) among treatments. Masticate NDF and ADF increased quadratically (P < or = 0.003) and N decreased linearly (P = 0.0001) as the grazing season progressed. Supplementation did not influence (P = 0.37 to 0.83) forage OM intake, total and lower tract OM digestibility, ruminal and total tract NDF digestibility, or total ruminal VFA; however, supplemented heifers had lower ruminal molar proportions of acetate (P = 0.01), higher ruminal molar proportions of butyrate (P = 0.007), and greater quantities of OM digested in the rumen (P = 0.10) and total tract (P = 0.02). As the grazing season progressed, total tract OM and N and ruminal NH3 concentrations and NDF digestibility decreased quadratically (P < or = 0.04). Microbial N flow (P = 0.09) and efficiency (P = 0.04) and postruminal N disappearance (P = 0.02) were greater for Control heifers and declined linearly (P < or = 0.02) as the grazing season advanced. Depressed microbial N flow seemed to be more pronounced for Oil than for the Corn treatment. Although total digestible OM intake increased with supplementation, metabolizable protein supply was reduced in supplemented heifers. Therefore, feeding low levels of supplemental grain with or without soybean oil is an effective strategy to increase dietary energy for cattle grazing high-quality forages, but consideration should be given to reduced supply of metabolizable protein.

Animal Feed↗

PubMed2001

Proportion of corn silage in diets of feedlot steers fed to achieve stepwise increases in growth.

Two experiments were conducted to investigate the effects of proportion of dietary corn silage during periods of feed restriction on performance of steers. In Exp. 1, Simmental x Angus steer calves (n = 107; initial BW = 273 +/- 3.8 kg) were allotted to 12 pens with eight or nine steers/pen and four pens/treatment. Periods of growth were 273 to 366 kg BW (Period 1), 367 to 501 kg BW (Period 2), and 502 to 564 kg BW (Period 3). In two of the dietary regimens, steers were given ad libitum access to feed throughout the experiment and were fed either a 15% corn silage diet in each period or an 85, 50, and 15% corn silage diet in Periods 1, 2, and 3; respectively. In the third feeding regimen, a programmed intake feeding regimen was used. Steers were fed a 15% corn silage diet in each period. However, feed intake was restricted to achieve a predicted gain of 1.13 kg/d in Period 1 and 1.36 kg/d in Period 2, and feed was offered for ad libitum consumption in Period 3. For the entire experiment, ADG was similar (P = 0.41) among treatments and feed efficiency was lower (P < 0.10) for steers in the corn silage regimen than for steers in the programmed intake and ad libitum regimens. In Exp. 2, Simmental x Angus steer calves (n = 106; initial BW = 233 +/- 2 kg) were allotted by BW to 12 pens (three pens/treatment) and fed in three periods similar to those described in Exp. 1. Four feeding regimens were investigated: 1) AL; steers were offered a 15% corn silage diet for ad libitum consumption in all three periods; 2) PI; DMI was programmed to achieve gains as described in Exp. 1; 3) CS-HLL; programmed intake as described above except diets contained 85, 15, and 15% corn silage in Periods 1, 2, and 3, respectively; and 4) CS-HIL; same feeding regimens as CS-HLL, except diets contained 85, 50, and 15% corn silage in Periods 1, 2, and 3, respectively. Steers were given ad libitum access to feed in Period 3. Overall ADG was lower (P < 0.05) for steers in the CS-HLL and CS-HIL feeding regimens than for steers in the AL and PI regimens; feed efficiency was greatest for steers in the PI regimen. Few effects of feeding regimen on carcass characteristics were observed.

Animal Feed↗

PubMed2002

Additivity and associative effects of metabolizable energy and amino acid digestibility of corn, soybean meal, and wheat red dog for White Pekin ducks.

The additivity of true amino acid digestibility (TAAD) and true metabolizable energy (TME) values in corn, soybean meal, and wheat red dog for White Pekin ducks was investigated. Differences between observed values for the complete diets and values predicted from measurements of individual ingredients were used to test additivity. Eight ducks were each assigned to the following dietary treatments: corn, soybean meal (44% CP), wheat red dog (wheat by-product with less than 4% fiber), complete Diet 1 (corn-soybean meal), complete Diet 2 (corn-red dog-soybean meal), and dextrose. Dextrose-fed ducks were used to estimate endogenous losses. The nitrogen-corrected TME (TMEn) in corn, soybean meal, wheat red dog, and two complete diets were 3.411, 2.919, 2.502, 3.148, and 3.111 kcal/g, respectively. In general, the TME and TMEn values observed in the two complete diets were not different (P > 0.05) from predicted values and indicated that the TME and TMEn in corn, soybean meal, and wheat red dog were all additive. The mean TAAD of corn, soybean meal, wheat red dog, and the two complete diets were not different, and were 87.03, 88.15, 90.58, 85.83, and 87.02%, respectively. The differences in TAAD between observed and predicted values were significant (P < 0.05) only for arginine, lysine, and aspartate in complete Diet 1, and for arginine, histidine, lysine, and aspartate in complete Diet 2. These results indicated that TME and TMEn values for corn,soybean meal, and wheat red dog were all additive in the two complete diets, but digestibilities of some amino acids were not additive and demonstrated some associative effects.

Amino Acids↗

PubMed2005

Corn hybrid affects in vitro and in vivo measures of nutrient digestibility in dogs.

Corn is a commonly used ingredient in dry pet foods because there is a stable supply and it is a relatively inexpensive source of nutrients. Corn hybrids are available that are higher in CP and amylose and lower in phytate concentration than conventional hybrids. Approximately 500 mg of high-protein (HP), high-protein, low-phytate (HPLP), and high-amylose (HA) corn were compared with conventional (CONV) corn and amylomaize starch (AM) in triplicate and exposed to pepsin/hydrochloric acid and pancreatin to simulate hydrolytic digestion. Substrate remaining after this was used to determine in vitro colonic fermentation. Organic matter disappearances as a result of hydrolytic digestion were >80% for CONV, HP, and HPLP, whereas HA (60.7%) and AM (43.7%) were lower (P < 0.05). Total digestion (TD) values after hydrolytic digestion and 8 h of fermentation using canine fecal inoculum were greater (P < 0.05) for CONV, HP, and HPLP vs. HA and AM. The residue left after hydrolytic digestion of all substrates was poorly fermented. Five ileal-cannulated dogs were fed each corn hybrid at approximately 31% of the diet in a 5 x5 Latin square design. Dogs fed diets containing HP corn had higher (P < 0.05) ileal OM digestibility (70.3%) and tended (P < 0.10) to have higher DM digestibility (64.6%). Ileal starch digestibilities were lower (P < 0.05) for dogs fed HA (64.0%) and AM (63.0%). Ileal digestibilities of essential (71.2%), nonessential (67.4%), and total (69.0%) AA tended to be higher (P < 0.10) for HP diets compared with CONV (66.4, 62.4, and 64.0%, respectively). Total-tract DM, OM, CP, and GE digestibilities (77, 82, 77, and 84%, on average, respectively) were higher (P < 0.05) for dogs fed CONV, HP, and HPLP than for those fed AM (66.9, 71.6, 72.6, and 76.5%) and HA (60.6, 65.7, 69.7, and 71.5%). Total-tract fat digestibilities were lower (P < 0.05) for dogs fed HA diets (86.6%) than for all other treatments (91.0%, on average). Total-tract starch digestibilities were higher (P < 0.05) for dogs fed CONV, HP, and HPLP (98%, on average) compared with HA (72.8%) and AM (76.5%). No differences were detected among treatments in fecal bifidobacteria, lactobacilli, or Clostridium perfringens concentrations. The experiments demonstrated that HP and HPLP corn had hydrolytic digestion and fermentation characteristics similar to those of CONV corn, whereas HA resulted in similar responses to AM, a well-established resistant starch ingredient.

Acids, Acyclic↗

PubMed2005

Methane emissions from feedlot cattle fed barley or corn diets.

Methane emitted from the livestock sector contributes to greenhouse gas emissions worldwide. Understanding the variability in enteric methane production related to diet is essential to decreasing uncertainty in greenhouse gas emission inventories and to identifying viable greenhouse gas reduction strategies. Our study focused on measuring methane in growing beef cattle fed corn- or barley-based diets typical of those fed to cattle in North American feedlots. The experiment was designed as a randomized complete block (group) design with two treatments, barley and corn. Angus heifer calves (initial BW = 328 kg) were allocated to two groups (eight per group), with four cattle in each group fed a corn or barley diet. The experiment was conducted over a 42-d backgrounding phase, a 35-d transition phase and a 32-d finishing phase. Backgrounding diets consisted of 70% barley silage or corn silage and 30% concentrate containing steam-rolled barley or dry-rolled corn (DM basis). Finishing diets consisted of 9% barley silage and 91% concentrate containing barley or corn (DM basis). All diets contained monensin (33 mg/kg of DM). Cattle were placed into four large environmental chambers (two heifers per chamber) during each phase to measure enteric methane production for 3 d. During the backgrounding phase, DMI was greater by cattle fed corn than for those fed barley (10.2 vs. 7.6 kg/d, P < 0.01), but during the finishing phase, DMI was similar for both diets (8.3 kg/d). The DMI was decreased to 6.3 kg/d with no effect of diet or phase while the cattle were in the chambers; thus, methane emissions (g/d) reported may underestimate those of the feedlot industry. Methane emissions per kilogram of DMI and as a percentage of GE intake were not affected by grain source during the backgrounding phase (24.6 g/kg of DMI; 7.42% of GE), but were less (P < 0.05) for corn than for barley during the finishing phase (9.2 vs. 13.1 g/kg of DMI; 2.81 vs. 4.03% of GE). The results indicate the need to implement dietary strategies to decrease methane emissions of cattle fed high-forage backgrounding diets and barley-based finishing diets. Mitigating methane losses from cattle will have long-term environmental benefits by decreasing agriculture's contribution to greenhouse gas emissions.

Animal Feed↗

PubMed2006

In situ studies on the time-dependent degradation of recombinant corn DNA and protein in the bovine rumen.

An in situ technique was adopted to investigate the time-dependent ruminal degradation of chloroplast compared with recombinant DNA of Bt176 corn using conventional and quantitative PCR assays. In parallel, the Cry1Ab protein content and fragment sizes were determined by ELISA and immunoblotting techniques. Triplicate nylon bags filled with 5 g of each substrate (whole-plant isogenic, whole-plant transgenic, ensiled isogenic, and ensiled transgenic corn) were positioned within the rumen of 5 rumen-cannulated, nonlactating cows and incubated for 2, 4, 8, 16, 24, and 48 h. To investigate the DNA degradation process, PCR assays were developed to detect fragments of the endogenous highly abundant rubisco gene (173, 896, 1,197, and 1,753 bp) and of the recombinant cry1Ab gene (211, 420, 727, and 1,423 bp). Short fragments of rubisco (<431 bp) and cry1Ab DNA (211 bp) were amplifiable in whole-plant and ensiled corn samples incubated in the rumen for 48 h, whereas the traceability of larger fragments depended on previous processing of the sample (whole-plant or ensiled corn), the length of the target sequence, and concomitantly on the length of time incubated in the rumen. Quantification of rubisco and cry1Ab gene fragments applying real-time PCR assays revealed degradation to <20% of initial 0-h values within 2 h and <0.5% after 48 h of ruminal incubation. Analysis of Cry1Ab protein in whole-plant corn using the ELISA technique revealed a decrease to 28.0% of the initial value within 2 h and to 2.6% within 48 h. The concentration of Cry1Ab protein of ensiled corn was only 10% that of whole-plant corn. Ensiled corn Cry1Ab protein decreased to 10% of initial values after 48 h of ruminal incubation. Using an immunoblotting technique, the full-size Cry1Ab protein was only detectable up to 8 h; thereafter, only fragments of approximately 17 and 34 kDa size were found. In conclusion, ruminal digestion decreased the presence of functional cry1Ab gene fragments. It is unlikely that full-size, functional Cry1Ab protein will be present after 8 h of incubation in the rumen. Therefore, results based on ELISA measurements should be interpreted carefully and verified by another detection method that discriminates between the full-size and fragmented Cry1Ab protein.

Animals↗

PubMed1987

Feeding combinations of dry corn and wheat to finishing lambs and cattle.

Two finishing trials, one with lambs and one with cattle, were conducted to determine the effect of combinations of dry corn (whole or rolled) with dry rolled wheat on animal performance. The cattle (mixed crossbred yearlings) trial also evaluated methods of getting cattle to full feed by stepping-up using either grain combinations or dry rolled corn and then feeding the appropriate grain combination. In the lamb trial, as the level of dry whole corn increased in the diet of 80 Rambouillet X Suffolk lambs (29 kg), feed intake (linear, P less than .01), gain (linear, P less than .01; quadratic, P less than .15) and feed efficiency (linear, P less than .01; quadratic, P less than .15) were improved. The major improvement occurred in the first 30 d of feeding when feed efficiency was improved (linear, P less than .01; quadratic, P less than .01) by the inclusion of dry whole corn. In the cattle trial (272 mixed crossbred yearling cattle, avg = 358 kg), as the level of dry rolled corn increased, feed intake (linear, P less than .01), gain (linear, P less than .01; quadratic, P less than .01) and feed efficiency (linear, P less than .05; quadratic, P less than .05) were improved. Cattle fed 67 or 33% dry rolled corn with 33 or 67% dry rolled wheat gained 4% faster and 4.4% more efficiently than the average performance of cattle fed 100% corn or wheat. Cattle stepped-up on dry rolled corn and then switched to 100% wheat, tended to gain faster (.1 kg/d) than cattle stepped-up on 100% wheat.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗