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PubMed1996

Influence of flake density on the feeding value of steam-processed corn in diets for lactating cows.

Four primiparous Holstein cows (112 d in lactation) with cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square design. Dry-rolled (DR) corn (density .52 kg/L) was compared with stream-flaked (SF) corn processed to three flake densities: .39, .32, and .26 kg/L. The basal diet contained (DM basis) 43.4% alfalfa hay, 39.5% corn (DR or SF), 2.2% yellow grease, 9.6% cane molasses, .7% sodium bicarbonate, and 4.6% protein-mineral supplement. Steam flaking increased DM intake (P < .01). There were no treatment effects on ruminal pH (P > .10). Ruminal molar ratios of acetate and propionate were lower (P < .01) for SF than for DR corn and declined (linear component, P < .01) as flake density decreased. Ruminal digestibility of OM was not affected (P > .10) by corn processing. Ruminal starch digestibility increased (linear component, P < .05) as flake density decreased. Ruminal ADF digestibility was decreased by SF (P < .01); this effect was exacerbated by degree of processing (linear component, P < .05). Ruminal N efficiency (duodenal nonammonia N/N intake) was greater (P < .10) for SF than for DR corn because of an improved (P < .10) microbial efficiency. Steam flaking at all densities increased postruminal digestibility of OM (42.4%, P < .01), starch (84.9%, P < .01) N (13.6%, P < .01), and lipid (11.8%, P < .05). Total-tract digestibilities of OM, N, starch, DE and ME were greater (15.2, 11.5, 25.2, 14.9, and 20.0%, respectively, P < .01) for SF (mean of the three densities) than for DR corn. Total-tract digestibility of starch increased (linear component, P < .10) with degree of processing. However, this effect was offset by decreased (linear and quadratic components, P < .05) ADF digestibility. Steam flaking improved the feeding value of corn for lactating cows by improving diet acceptability and digestibility of lipid, starch, and N. Steam flaking increased the estimated NEl of corn by 33%. Optimal flake density probably is between .32 and .39 kg/L.

Animal Feed↗
PubMed1996

Limit-feeding corn as an alternative to hay for gestating beef cows.

Three experiments were conducted to determine the efficacy of limit-feeding corn-based diets as an alternative to hay for beef cows in gestation and early lactation. Seventy or 71 mature, pregnant Simmental crossbred cows (average weight = 589 +/- 10 kg) were used in each trial. Each of 29 or 30 cows was fed approximately 5 kg of whole shelled corn, 1.2 kg of a pelletted supplement, and 1 kg of hay daily from November to April to meet nutritional needs for gestation. The remaining 41 cows were fed first-cutting round-baled hay free choice. Cows with ad libitum hay intake consumed approximately twice as much feed as cows limit-fed the corn-based diet. Body weight change during the winter was not affected (P > .10) by feeding system in Trials 1 and 2. Limit-feeding the corn-based diet had no detrimental effects on subsequent cow performance or conception rate or on calf weaning weight following summer grazing on pasture. The cost to feed a cow hay was nearly double that of limit-feeding corn-based diet. Two additional experiments were conducted to determine the effect of supplemental monensin (200 mg/d) on performance of gestating Simmental-Angus first-calf heifers fed corn-based diets. In Trial 4, monensin-supplemented heifers were fed 10% less corn than control heifers. In Trial 5, both groups were fed equal amounts of feed. No adverse effects of feeding the corn-based diets were observed. It was concluded from these trials that corn-based diets can meet the nutrient requirements of pregnant beef cattle without adverse effects on production and at a lower cost than feeding hay.

Animal Feed↗
PubMed1999

Rate and extent of digestion of the ethanol-soluble and neutral detergent-insoluble fractions of corn grain.

The objectives of this study were to partition corn grain into three digestible fractions and to measure the rate of disappearance of these fractions in vitro. Seventeen corn grain samples with varied fiber concentrations were extracted with either 80% ethanol or neutral detergent to obtain estimates of the pool size and digestion kinetics of the A, B1, B2, and C fractions. The carbohydrate soluble in 80% ethanol averaged only 2.6+/-.3% of the DM, although 80% ethanol extracted 7.1+/-1.2% of DM of corn grain. The ethanol-soluble fraction of corn grain contained protein, ether-extractable compounds, and a small amount of ash in addition to carbohydrate. Because of this chemical heterogeneity and because of the small size of the ethanol-soluble fraction, it was not possible to determine the digestion rate of this fraction by measuring gas production. The NDF content of the corn grain was 10.6+/-.7% of DM and was highly digestible (94.6+/-1.4%). The digestible NDF contributed 9.5% of the total gas production from corn grain. Because the size, digestibility, and digestion rate of the digestible NDF fraction varied little among corn grain samples, it is not necessary to routinely analyze the digestion kinetics of the digestible NDF fraction of dried corn grain. An average gas production curve of this fraction can be used as a base to subtract from the total gas production curve to generate the gas production curve of the neutral detergent-soluble fraction for dried, ground corn grain samples.

Detergents↗
PubMed1999

Supplemental cracked corn for steers fed fresh alfalfa: I. Effects on digestion of organic matter, fiber, and starch.

The effect of supplementation with different levels of cracked corn on the sites of OM, total dietary fiber (TDF), ADF, and starch digestion in steers fed fresh alfalfa indoors was determined. Six Angus steers (338 +/- 19 kg) fitted with cannulas in the rumen, duodenum, and ileum consumed 1) alfalfa (20.4% CP, 41.6% NDF) ad libitum (AALF); 2), 3), and 4) AALF supplemented (S) with .4, .8, or 1.2%, respectively, of BW of corn; or 5) alfalfa restricted at the average level of forage intake of S steers (RALF), in a 5 x 5 Latin square design. Total OM intake was lower (P < .01) in steers fed RALF than in those fed AALF but level of forage intake did not affect sites of OM, TDF, or starch digestion (P > .05). Forage OM intake decreased (P < .01) linearly (8,496 to 5,840 g/d) but total OM intake increased (P = .03) linearly (8,496 to 9,344 g/d) as corn increased from .4 to 1.2% BW. Ruminal apparent and true OM disappearance was not affected, but OM disappearing in the small intestine increased (P < .01) linearly with increasing levels of corn. Total tract OM digestibility (71.2 to 76.2%) and the proportion of OM intake that was digested in the small intestine (15.4 to 24.5%) increased (P < .01) linearly as corn increased. The TDF and ADF intakes decreased (P < .01) linearly as level of corn increased. Total tract TDF and ADF digestibilities were not different among treatments (average 62.9 and 57.8%, respectively). Starch intake and starch digested in the rumen and small and large intestine increased (P < .01) linearly with increasing corn level. Ruminal pH and VFA concentrations decreased and increased (P < .01), respectively, with increasing corn. Supplementation with corn increased OM intake, decreased forage OM intake, and increased the proportion of OM that was digested in the small intestine, but fiber digestion was not affected.

Animals↗
PubMed2001

Low-phytic acid corn improves nutrient utilization for growing pigs.

Thirty-five crossbred barrows averaging 14.5 kg initial BW were used in a 5-wk experiment to compare the P availability and nutritional value of a low-phytate hybrid corn (LPC, 0.26% total P, 0.08% phytic acid P) homozygous for the lpa 1-1 allele with a nearly isogenic normal hybrid corn (NC, 0.25% total P, 0.20% phytic acid P). The pigs were fed individually twice daily in metabolism pens. Three semipurified diets were created in which corn was the only source of phytate. Diet 1 contained 72% NC, 0.15% estimated available P (aP) and 0.55% Ca. Diet 2 contained 72% LPC, 0.24% aP, and 0.55% Ca. The only differences between Diets 1 and 2 were the source of corn and the levels of aP. No inorganic P (iP) was added to these diets in order to measure the animal response to the different levels of aP in the corn hybrids. Diet 3 was NC Diet 1 supplemented with iP to equal the level of aP in LPC Diet 2. Diets 4 and 5 were practical corn-soybean meal diets formulated with each corn to meet all minimum nutrient requirements and contained 0.30% aP and 0.65% Ca. For the semipurified diets, pigs fed LPC Diet 2 had higher (P < 0.01) growth performance, bone breaking strength, P absorption and retention, Ca absorption and retention, and N retention than pigs fed NC Diet 1. However, when the NC diet was supplemented with iP to equal the aP in the LPC diet, most criteria were similar (P > or = 0.2), indicating an equal nutritional value for both corn hybrids after adjusting for phytate level. The only treatment difference, other than P excretion, between the practical corn diets supplemented with soybean meal was a higher (P < 0.05) bone breaking strength for pigs fed LPC Diet 5 compared with NC Diet 4. The use of LPC in pig diets reduced P excretion in swine waste by 50 and 18.4% in the semipurified and practical diets, respectively, compared with NC. Using our in vitro procedure designed to simulate the digestive system of the pig, the availability of P for pigs was estimated at 56% for LPC and 11% for NC.

Animal Feed↗
PubMed2001

Effects of feeding high-oil corn to beef steers on carcass characteristics and meat quality.

To assess the effects of feeding high-oil corn on carcass characteristics and meat quality, 60 yearling steers were fed high concentrate diets containing either control corn (82% of diet), high-oil corn (82% of diet), or high-oil corn at a concentration that was isocaloric with the control diet (74% of diet). After being fed for 84 d, steers were slaughtered. At 72 h postmortem, carcass data were collected and rib sections from five steers grading U.S. Choice and five steers grading U.S. Select from each treatment were collected, vacuum packaged, and aged for 14 d. Three steaks (2.54 cm thick) were removed from each rib for Warner-Bratzler shear force measurement, sensory appraisal, and fatty acid composition analyses. Data were analyzed with treatment as the main effect for the carcass data and treatment, quality grade, and two-way interaction in the model for the longissimus data. The two-way interaction was nonsignificant (P > 0.05) for all variables tested. No differences were detected (P > 0.05) in carcass measurements except for marbling scores and quality grades, both of which were greater (P < 0.05) for carcasses from steers fed the high-oil corn. Overall, 78% of steers fed the high-oil corn graded U.S. Choice compared with 47% for the control and 67% for isocaloric group. Shear force and sensory properties of the longissimus were not different (P > 0.05) among treatments. Steaks from U.S. Choice carcasses rated higher (P < 0.05) for tenderness and tended to rate higher (P < 0.10) for juiciness. Feeding the isocaloric and high-oil diets increased (P < 0.05) linoleic acid, arachidonic acid, and the total PUFA content of lipid extracted from the longissimus. Saturated fatty acid percentage was lowest (P < 0.05) for high-oil corn and highest (P < 0.05) for control, with isocaloric being intermediate. Feeding high-oil corn increased (P < 0.05) pentadecyclic acid, margaric acid, and total odd-chain fatty acid content. Feeding high-oil corn in finishing beef cattle diets enhanced intramuscular lipid deposition and increased unsaturation of fatty acids of the longissimus.

Animal Feed↗
PubMed2005

Effect of cutting height and genetics on composition, intake, and digestibility of corn silage by beef heifers.

This research was conducted to determine the effect of corn genetics and cutting height on the composition and nutritive characteristics of corn silage. An in situ study involving eight commercially available corn hybrids indicated main effects and interactions (P < 0.01) of hybrid and cutting height on NDF, ADF, and starch content and on in situ DM and NDF degradablility. Four ruminally cannulated Angus heifers (initial BW = 378 +/- 3 kg) were used in a 4 x 4 Latin square digestion experiment with a 2 x 2 factorial treatment arrangement. Main effects and interactions of hybrid (Pioneer Hi-Bred Int., Inc., hybrids 3335 and 3223) and cutting height (LO = 20.3 cm, and HI = 61 cm) were evaluated. Dietary treatment consisted of 40% chopped alfalfa hay and 60% corn silage. Although corn silage hybrids used were of equivalent maturity at harvest (60% milkline), 3335 treatments had 37.8% starch and 34.8% NDF, whereas 3223 treatments had 33.7% starch and 38.6% NDF. The LO treatments averaged 3.1 percentage units greater in NDF and 3.45 percentage units less in starch content than the HI treatments. Intake of DM was greater for heifers fed 3335-HI than 3335-LO; however, DMI was greater by heifers fed 3223-LO than 3223-HI (hybrid x cutting height interaction, P < 0.05). Starch intake was greater (P < 0.05) and NDF intake was less (P < 0.05) by heifers fed HI vs. LO and fed 3335 vs. 3223 dietary treatments. Digestibility of DM, starch, and NDF was greater (P < 0.05) by heifers fed 3223 than 3335 dietary treatments, but digestibility differences were not observed (P > 0.10) between cutting heights. Rate of in situ DM and starch degradability was not affected (P > 0.10) by hybrid or cutting height; however DM degradability was greater (P < 0.05) for HI than LO corn silage substrates at 8, 16, and 24 h of incubation. Rate of NDF degradability tended (P = 0.08) to be greater for 3223 than for 3335, and for LO compared with HI corn silage. Degradability of NDF was greater (P < 0.05) for 3223 compared with 3335 substrates at 24, 36, and 48 h of incubation. These data suggest fiber may not be an accurate measure of corn silage quality. Whereas cutting height affected chemical composition, we observed genetics to have a greater effect on corn silage quality.

Ammonia↗
PubMed2006

Impact of corn vitreousness and processing on site and extent of digestion by feedlot cattle.

Eight cannulated Holstein steers (average BW: 251 kg) were used in 2 simultaneous 4 x 4 Latin squares in a split-plot arrangement to test the effects of processing method [dry-rolled (DR) vs. steam-flaked (SF); main plot] and vitreousness (V, %; subplot) of yellow dent corn (V55, V61, V63, and V65) on site of digestion of diets containing 73.2% corn grain. No vitreousness x processing method interactions were detected for ruminal digestion, but ruminal starch digestion was 14.4% lower (P < 0.01) for DR than for SF corn. Interactions were detected between vitreousness and processing method for postruminal (P < 0.10) and total tract digestion (P < 0.05). With DR, vitreousness tended to decrease (linear effect, P < 0.10) postruminal OM and starch digestion. With SF, vitreousness did not affect (P > or = 0.15) postruminal digestion of OM and starch. Postruminal N digestion tended to decrease (linear effect, P = 0.12) as vitreousness increased. Postruminal digestion was greater for SF than for DR corn OM (25.7%, P < 0.05), starch (94.3%, P < 0.10), and N (10.7%, P < 0.01). Steam flaking increased total tract digestion of OM (11%, P < 0.05), starch (16%, P < 0.01), and N (8.4%, P < 0.05) but decreased total tract ADF digestion (26.7%, P < 0.01). With DR, total tract starch digestion was lower for V65 (cubic effect, P < 0.10) than for the other hybrids. With SF, total tract starch digestion was not affected (P > or = 0.15) by vitreousness. Fecal starch and total tract starch digestion were inversely related (starch digestion, % = 101 - 0.65 x fecal starch, %; r2 = 0.94, P < 0.01). Ruminal pH was greater for steers fed DR than for steers fed SF corn (6.03 vs. 5.62, P < 0.05). Steam flaking decreased (P < 0.01) the ruminal molar proportion of acetate (24%), acetate:propionate molar ratio (55%), estimated methane production (37.5%), and butyrate (11.3%, P < 0.05). There was a vitreousness x processing interaction (P < 0.01) for acetate:propionate. For DR, acetate:propionate tended to increase (linear effect; P < 0.10) with increasing vitreousness. With SF, acetate:propionate was greater (cubic effect, P < 0.01) for V65. Starch from more vitreous corn grain was less digested when corn grain was DR, but this adverse effect of vitreousness on digestion was negated when the corn grain was SF. Of the 19% advantage in energetic efficiency associated with flaked over rolled corn grain, about 3/4 can be attributed to increased OM digestibility, with the remaining 1/4 ascribed to reduced methane loss.

Animal Feed↗
PubMed1980

Ammoniation of corn contaminated with aflatoxin and its effects on growing rats.

Corn naturally contaminated with 2,000 ppb total aflatoxin was adjusted to 17% moisture and ammoniated (Am) with 1.5% (w/w) anhydrous ammonia in an attempt at detoxification. The ammonia treatment reduced the detectable concentration to 510 ppb total aflatoxins. Ninety-six male Sprague-Dawley rats (75 g avg) were randomly divided into eight treatment groups with 12 rats per treatment. A fortified 12%-protein corn-soybean meal diet served as the control (C) diet. The corn used in the C diet contained no detectable aflatoxin. Treatment 2 contained 1,670 ppb aflatoxin; treatments 3 and 4 were similar to treatments 1 and 2, respectively, except the corn used was ammoniated. Treatments 5 through 8 contained 830, 420, 210 and 100 ppb total aflatoxin, respectively. Liver weights expressed as a percentage of final live weight were increased (P less than .05) in rats consuming diets containing 1,670 ppb aflatoxin compared to the other treatments. Serum albumin, IgG and IgM concentrations were not affected by ammoniation or by concentration of aflatoxin in the corn. At the end of 4 weeks, total serum protein was increased (P less than .05) in rats consuming diets containing aflatoxin-contaminated (AfC) corn and Am corn compared to those consuming the C diet. Average daily gain and average daily feed consumption were reduced (P less than .01) in rats consuming the diet containing 1,670 ppb aflatoxin. The growth of rats consuming AfC corn that was Am was equal to that of rats consuming a similar concentration of aflatoxin by dilution. From these results and the results of others, it appears that ammoniation of corn contaminated with aflatoxin may be a practical and economical method for detoxification.

Aflatoxins↗
PubMed1985

Utilization by sheep of whole shelled corn impregnated with urea, calcium, potassium and sulfur.

Twenty-eight growing wether lambs (33.9 kg), adapted to urea for 40 d, were used in a metabolism study to determine if urea impregnation of corn could improve urea utilization. The following diets were compared: 1) whole shelled corn alone, 2) whole shelled corn impregnated with urea, calcium (Ca) as CaCl2, potassium (K) as KC2H3O2, and sulfur (S) as Na2S2O3 X 5H2O, 3) whole shelled corn fed with a dry supplement containing urea, Ca, K and S and 4) whole shelled corn fed with a dry supplement containing soybean meal, Ca and K. Additions were made to provide diets containing 12% crude protein, .37% Ca and .50% K. A 10:1 N (from urea) to S ratio, dry basis was used in urea-containing diets. Corn (90% dry matter) in diet 2 was impregnated by spraying 1.1 liters of an aqueous solution containing the above salts per 10 kg of corn dry matter. After mixing for 10 min in a horizontal mixer, the corn was dried in a laboratory grain drying bin with ambient laboratory air for 48 h. Lambs were fed 350 g of the respective diets plus 35 g orchardgrass hay twice daily during a 20-d metabolism trial. On the last day of the trial, ruminal fluid samples were collected at 0, 1, 2, 3, 4, 5 and 6 h postfeeding and jugular blood was obtained at 0 and 6 h postfeeding. Nitrogen-supplemented diets resulted in increased (P less than .01) absorption and retention of N. Digestibility of dry matter, organic matter and NFE tended to be greater in lambs fed impregnated corn than in lambs fed the other diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1986

Effect of dry, high-moisture and reconstituted normal and high-lysine corn diets and particle size on energy and nitrogen metabolism in growing swine.

Two metabolism studies were conducted with 24 (Exp. 1) and 36 (Exp. 2) crossbred barrows (initial weight 35 kg) to determine the effect of corn type--normal corn (NC) and high-lysine corn (HLC)--and storage method--dry (D), high-moisture (HM) and reconstituted (RC)--on energy and N digestibility. Diets fed in Exp. 1 were: 1, NC-soybean meal formulated at .78% lysine (dry matter basis); 2, HLC-soybean meal containing the same amount of corn as diet 1 (.87% lysine); 3, HLC-soybean meal with the same lysine level as diet 1. In Exp. 1, dry matter, energy and N digestibilities were not different between corn types or lysine levels (P greater than .16). These results indicate that energy and N digestibility of HLC in typical diets for growing swine are similar to those for NC diets when both are balanced on a lysine basis. Also, replacing NC with HLC on an equal-weight basis did not affect energy and N digestibility. In Exp. 2 six diets balanced on an isonitrogenous and dry-matter basis were tested. Normal corn and HLC diets, which had been stored by three different methods (D, HM and RC) were arranged in a 2 X 3 factorial plan. There were no differences between corn types in dry matter, energy and N digestibilities. The HM and RC treatments had larger particle sizes than the dry corn diets. For diets balanced on an isonitrogenous basis, dry corn storage improved energy digestibility (P less than .10). Reconstitution appeared to improve energy balance and N digestibility of HLC, while HM storage improved energy balance and N digestibility of NC.

Animal Feed↗
PubMed1987

Evaluation of rare-earth markers using an in vitro ruminal fermentation system and effect of processing method on ruminal turnover of sized corn particles.

A two-stage in vitro ruminal fermentation experiment was conducted to determine the extent of marker migration and the effects of marker addition on digestibility. Fermentation studies were terminated either at the end of stage I, the fermentation phase, or stage II, the pepsin digestion phase. Treatment diets contained ytterbium-marked corn plus chopped Coastal bermudagrass hay and nonmarked corn plus chopped hay. After stage I of the in vitro ruminal fermentation, 90% of ytterbium was recovered. Of this, 8.8% of the ytterbium had migrated to the hay, 2% was recovered in the supernatant and 89.2% remained bound to the corn. After completion of both stages, 72% was recovered, of which 7.9% was bound to corn, 33.6% was bound to the hay, 1.1% was recovered in the stage I supernatant and 57.4% was associated with the acid pepsin supernatant. Dry matter digestion was not affected after stage I but after stage II, digestibility was decreased 7% due to marker addition. A ruminal-cannulated Holstein steer weighing approximately 680 kg was used to determine turnover rates from the rumen of liquid and five different particle sizes of corn. Corn from each of two processing methods was fractionated into five particle sizes by dry-sieving. The corn particles included steam-rolled corn (SRC) retained on a 4-mm sieve and marked with dysprosium, SRC retained on a 2-mm sieve and marked with erbium, cracked corn (CC) retained on a 4-mm sieve and marked with yttrium, CC retained on a 2-mm sieve and marked with ytterbium, and CC retained on a 1-mm sieve and marked with samarium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Effects of brown midrib 3 mutation in corn silage on productivity of dairy cows fed two concentrations of dietary neutral detergent fiber: 3. Digestibility and microbial efficiency.

The effects of digestibility of corn silage neutral detergent fiber (NDF) and dietary NDF content on ruminal digestion kinetics, site of nutrient digestion, and microbial N production efficiency were evaluated with eight multiparous high producing dairy cows in a duplicated 4 x 4 Latin square design with 21-d periods. Experimental diets contained corn silage from a brown midrib (bm3) hybrid or its isogenic normal control at two concentrations of dietary NDF (29 and 38%). The NDF digestibility estimated by a 30-h in vitro fermentation was higher for bm3 corn silage by 9.4 units (55.9 vs. 46.5%). Neither ruminal nor total tract NDF digestibility was affected by corn silage treatment. The bm3 corn silage diet decreased starch digestibility in the rumen and in the total tract, but increased postruminal starch digestibility compared with control diet. The bm3 corn silage diets increased microbial N flow to the duodenum and tended to decrease ruminal ammonia concentration. Microbial efficiency was greater for cows fed bm3 corn silage in spite of lower ruminal pH. Higher efficiency of microbial nitrogen production might be attributed to faster passage rate of NDF for cows fed bm3 corn silage compared with those fed control corn silage. Higher in vitro NDF digestibility might predict enhanced NDF fragility and ease of NDF hydrolysis in vivo. Enhanced in vitro NDF digestibility does not necessarily result in increased NDF digestibility either in the rumen or in the total tract, but possibly increases rate of passage and DMI, improving efficiency of microbial N production.

Animal Feed↗
PubMed2000

Effects of corn processing and supplemental hay on rumen environment and lactation performance of dairy cows grazing grass-legume pasture.

The effect of corn processing (9 kg of dry matter/d of ground dry shelled or 9 kg of dry matter/d of steam rolled) and supplemental hay (0 or 3.2 kg of dry matter/d of alfalfa hay) on milk yield and composition, rumen environment, and starch utilization by lactating cows grazing grass-legume pasture was studied. Twelve rumen cannulated, multiparous Holstein cows in early lactation (95 d in milk), were assigned to a 4 x 4 Latin square design replicated three times. Treatments were ground shelled corn-based concentrate, ground shelled corn-based concentrate plus alfalfa hay, steam-rolled, corn-based concentrate, or steam-rolled, corn-based concentrate plus alfalfa hay. Supplements were fed in equal proportions twice daily. Cows fed steam-rolled corn tended to have higher percentage of milk protein and lower milk urea nitrogen concentrations than cows fed shelled corn. Milk yield was not affected by corn processing or hay supplementation. Intake of pasture forage but not total dry matter intake was reduced by hay supplementation. Starch plus free glucose digestibility in the total tract was not affected by grain processing; however, starch plus free glucose digestibility tended to increase with hay supplementation. Supplemental hay increased starch plus free glucose digestibility through changes in rumen digestion kinetics. Hay supplementation reduced the liquid rate of passage, and tended to reduce particulate turnover. Rumen degradability of pasture forage organic matter tended to be higher for cows fed supplemental hay. Supplemental hay in these diets had a greater impact on starch utilization than corn processing.

Animal Feed↗
PubMed2001

Effects of NutriDense and waxy corn hybrids on the rumen fermentation, digestibility and lactational performance of dairy cows.

The objectives of this study were to determine the effects of NutriDense and waxy corn hybrids as silage and grain sources on milk yield, milk composition, digestibility of dietary components, and rumen characteristics. Six multiparous (intact) and six primiparous (ruminally cannulated) Holstein cows were assigned at 72 to 90 d of lactation to a 3 x 6 Latin rectangle design experiment to treatment of: 1) control diet, 2) NutriDense corn diet, and 3) waxy corn diet. Diets consisted of 10.9% alfalfa silage, 32.8% corn silage, 27.9% cracked corn grain, and 28.4% other ingredients (DM basis). Milk, FCM, and milk fat and protein yields were higher for cows fed the waxy diet than those fed the control diet. Milk protein percentage tended to be higher for cows fed the control and waxy diets than those fed the NutriDense diet. Dry matter intake tended to be higher for cows fed the waxy diet than the NutriDense diet. Apparent DM, OM, CP, ADF, NDF, and gross energy digestibilities were similar among dietary treatments, while apparent starch digestibility was higher for the waxy corn than for the NutriDense corn. Rumen NH3-N concentration was higher for cows fed the NutriDense diet than for those fed the control and waxy diets. The proportion of ruminal propionate was higher for the waxy diet than the control diet. NutriDense and waxy corn hybrids can be effective substitutes for conventional yellow dent corn hybrids in lactating dairy cow rations.

Ammonia↗
PubMed2001

Comparison of corn silage hybrids for yield, nutrient composition, in vitro digestibility, and milk yield by dairy cows.

A study was undertaken to compare Novartis N29-F1, a dual-purpose 90-d relative maturity corn hybrid, and Novartis NX3018, a 90-d relative maturity leafy corn silage hybrid for dry matter (DM) yield, in vitro digestibility, plant components, nutrient composition, and lactational performance by Holstein cows. The two corn hybrids were planted in replicated 15.2- x 321-m plots. Plant population and DM yield were similar between the two corn hybrids. Novartis NX3018 had higher content of crude protein and ash, a higher proportion of leaves and stalks, and a lower proportion of grain compared with Novartis N29-F1. The cob, grain, and leaves of Novartis NX3018 had higher in vitro true DM and neutral detergent fiber disappearances compared with the respective plant components of Novartis N29-F1. Thirty-eight midlactation multiparous Holstein cows (78 +/- 23.0 days in milk) producing 47.2 +/- 8.9 kg of milk per cow per day were blocked and assigned randomly to one of two total mixed ration (TMR) containing (DM basis) approximately 26% Novartis N29-F1 or Novartis NX3018 corn silage. Cows were housed in a free-stall barn and group fed ad libitum. The lactation study was conducted as a crossover design with two 28-d periods. Samples and data were collected during the final 7 d of each period. The total mixed rations were formulated using the Cornell-Penn-Miner Dairy nutrition model. Cows that were fed the total mixed rations containing Novartis NX3018 corn silage produced higher yields of milk 3.5% fat-corrected milk (FCM), milk crude protein, and milk lactose compared to cows that were fed the TMR containing Novartis N29-F1 corn silage. In conclusion, the Novartis NX3018 corn hybrid was leafier and more digestible in vitro, and when fed to dairy cows as silage, promoted higher milk yield compared with the Novartis N29-F1 corn hybrid.

Animals↗
PubMed2002

Influence of corn processing and frequency of feeding on cow performance.

Twenty cows, including five fitted with rumen cannulae, were used to study the influence of corn processing and frequency of feeding on milk yield and ruminal fermentation characteristics. Cows were assigned to five treatments in a 5 x 5 Latin square experiment. Each period was 3 wk. Cows were fed 45% forage and 55% grain in a total mixed ration. Diets contained 35% corn either coarsely ground and fed once a day (1x), finely ground (FGC) fed 1x, steam-flaked (SFC) fed lx, FGC fed four times a day (4x), or SFC fed 4x. Processing of corn and frequency of feeding had no influence on dry matter intake. Digestibility of starch was increased 6 and 3 percentage units by feeding SFC corn compared with coarsely and finely ground corn, respectively. Cows fed SFC or FGC produced 4% more milk with lower fat content compared with coarsely ground corn. Increasing the feeding frequency did not improve milk fat content. The fat-corrected milk yield was not different among treatments. Feeding SFC resulted in a low acetate-to-propionate ratio in the rumen fluid than FGC. Cows fed SFC produced 45 and 115 g more milk protein per cow/d than cows fed FGC or coarse, respectively. With the value of increased milk protein observed in this study, it would be more economical to feed SFC or finely ground corn to dairy cows compared with coarse ground. The breakeven price of flaking corn in this study was $32 and $12/metric tonne compared with coarse and FGC, respectively. Based on a survey conducted by the authors, the price of flaking corn in the United States ranged between $7 to $22/metric tonne during year 2000.

Animal Feed↗
PubMed2002

Whole linted cottonseed as a forage substitute fed with ground or steam-flaked corn: digestibility and performance.

Six ruminally and duodenally cannulated Holstein cows were used in a 6 x 6 Latin square design. The objective was to evaluate any potential interactions in site of nutrient digestion when neutral detergent fiber (NDF) from cottonseed was incrementally substituted for forage NDF (FNDF) from alfalfa silage and when starch availability was varied by feeding ground (G) or steam-flaked (SF) corn. Iso-NDF diets were forage control with G corn (21% FNDF), 5% whole cottonseed (WCS) with G or SF corn (18% FNDF), 10% WCS with G or SF corn (15% FNDF), and 15% WCS with G corn (12% FNDF). Ruminal or total tract digestibilities of organic matter (OM) or nonstructural carbohydrate (NSC) were unaffected, but efficiency of microbial protein synthesis decreased as WCS increased. Ruminal NDF digestibility was not affected despite a linear decrease in pH, but postruminal NDF digestibility decreased with increasing WCS. Ruminal digestibilities of OM and NSC were higher for SF than G corn but did not affect efficiency of microbial N synthesis. Dry matter intake increased quadratically with increasing level of WCS but decreased when SF replaced G corn. Milk yield did not differ across treatments. Milk fat percentage was affected quadratically and milk protein increased linearly with increasing WCS. Milk fat percentage decreased but milk protein was not affected when SF replaced G corn. Lack of an interaction between corn source and level of WCS substitution suggests that WCS was equally effective in maintaining ruminal fermentation and digestibility in diets varying in ruminal starch availability.

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