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PubMed2000

Performance and meat quality of beef steers fed corn-based or bread by-product-based diets.

A feeding trial was conducted with beef breed steers (120) to determine the effects of substituting bread by-product (BBy) for whole shelled corn on performance and meat quality. Chemical analysis of each diet ingredient and in vitro rates of digestion from gas production of BBy and corn were determined to provide accurate information for diet evaluations using the 1996 Beef NRC Model Level 2. Bread by-product contained 16% CP (75.6% degradable) and 75.1% non-structural carbohydrates (70% as starch, which had a digestion rate of 16%/h). The steers were given one estrogenic implant (Synovex-S) and started on the experiment at 15 mo of age and an average weight of 364 kg. The cattle were commercially slaughtered in three groups (40 steers at 101, 60 steers at 126, and 20 steers at 160 d on feed) weighing an average of 553 kg when they reached a small degree of marbling. Carcasses were electrically stimulated to prevent cold shortening of muscles. Warner-Bratzler shear force values were measured in rib steaks at 5, 14, and 21 d after slaughter (n = 76). Rib steaks from 30 steers per treatment were evaluated for palatability traits. Use of BBy at 55% of the diet (substituted for 75% of the corn) significantly improved feed efficiency by 8.1%. There were no statistically significant differences between the two diets for effects on ADG, carcass characteristics, shear force values, or sensory panel ratings of tenderness, juiciness, flavor, or overall acceptability. After adjusting intestinal starch digestibility in Level 2 to 63% for the whole corn and 90% for the BBy, predicted ADG matched that observed. Apparent NE(g) values for BBy and corn were 1.57 and 1.41 Mcal/kg, respectively.

Animal Feed↗
PubMed2000

Effects of graded levels of potato by-products in barley- and corn-based beef feedlot diets: II. Palatability.

The objective of this study was to evaluate the effects of barley- or corn-based diets containing 0, 10, or 20% potato by-product (DM basis) on Warner-Bratzler shear force and palatability of beef. One hundred forty-four crossbred beef steers (333+/-.44 kg) were allotted within weight block (3) to a randomized complete block design with a 2 x 3 factorial arrangement of dietary treatments. Main effects were grain (barley or corn) and level of potato by-product (0, 10, or 20% of diet DM). There were a total of 18 pens with eight steers per pen and three pens per treatment. Steers were fed diets containing 83% concentrate (grain plus potato by-product), 10% supplement, and 7% alfalfa (DM basis) for an average of 130 d. Longissimus muscle cuts were used for Warner-Bratzler shear force determination (four steers per pen) and evaluation (two steers per pen) by a 10-member trained laboratory panel, a professional flavor/texture profile panel, and by consumer panels. Diet did not affect (P > .10) Warner-Bratzler shear force or trained laboratory panel tenderness, juiciness, and flavor intensity scores. Flavor/texture profile panel scores indicated feeding a corn-based diet as opposed to barley-based diet produced a more appropriate well-balanced and well-blended beef flavor and texture. However, the magnitudes of the differences were relatively small, and flavor and texture amplitude ratings for both barley- and corn-fed beef were well above average. Beef from steers fed 10 or 20% potato by-product had lower (P < .05) incidences of inappropriate aromatics and aftertastes, which may have a slightly beneficial effect on beef flavor, but flavor amplitude was not affected (P > .05) by level of potato. Moreover, consumer panel overall acceptability scores were not affected by diet. Thus, feedlot diets containing corn or barley with or without potato by-product should result in palatable beef products.

Animal Feed↗
PubMed2001

Effect of hybrid, maturity, and mechanical processing of corn silage on intake and digestibility by beef cattle.

A study involving a 2 x 2 x 2 factorial arrangement of treatments was conducted to evaluate effects of hybrid (Pioneer 3335 and 3489), maturity (half milkline and blacklayer), and mechanical processing (field chopper with and without on-board rollers engaged) on intake and digestibility of corn silage. Forty Angus steers (322 +/- 5.2 kg BW) were assigned to the eight silage treatments (five steers per treatment) and individually fed using electronic gates. Diets consisted of 60% corn silage and 40% chopped alfalfa hay (DM basis). Following a 5-d adaptation period, intake was measured for 7 d and subsequently fecal samples were collected for 5 d. Chromic oxide (5 g/d) was fed beginning 7 d before fecal sample collection and digestibility was determined by the ratio of Cr in the feed and feces. Steers were reallocated to treatments and these procedures were repeated, providing 10 observations per treatment. In addition, all silages were ruminally incubated in six mature cows for 0, 8, 16, 24, 48, and 96 h to determine extent and rate of DM, starch, NDF, and ADF disappearance. Processing increased DMI of hybrid 3489 but did not affect DMI of hybrid 3335 (hybrid x processing; P < 0.06). Total tract digestibility of DM, starch, NDF, and ADF decreased (P < 0.01) as plant maturity increased. Maturity tended to decrease starch digestibility more for hybrid 3489 than for hybrid 3335 (hybrid x maturity; P < 0.10). Processing increased (P < 0.01) starch digestibility but decreased (P < 0.01) NDF and ADF digestibility, resulting in no processing effect on DM digestibility. There was a numerical trend for processing to increase starch digestibility more for latethan for early-maturity corn silage (maturity x processing; P = 0.11). Processing increased in situ rates of DM and starch disappearance and maturity decreased in situ disappearance rates of starch and fiber. These data indicate that hybrid, maturity, and processing all affect corn silage digestibility. Mechanical processing of corn silage increased starch digestibility, which may have been associated with the observed decreased fiber digestibility.

Adaptation, Physiological↗
PubMed2002

Neutral detergent fiber concentration of corn silage and rumen inert bulk influences dry matter intake and ruminal digesta kinetics of growing steers.

Corn silage with high NDF concentration has the potential to reduce DMI because it has a greater filling effect in the rumen than low-NDF corn silage. Our objective was to determine whether ruminal fill influences DMI to the same extent with low- or high-NDF corn silage-based diets. Eight ruminally cannulated Holstein steers (198 +/- 13 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design with 16-d periods. Treatments were diets containing corn silage from a normal hybrid (low-fiber; LF) or its male-sterile isogenic counterpart (high-fiber; HF), offered for ad libitum consumption to steers with or without rumen inert bulk (RIB). The LF and HF diets contained 33.8 and 50.8% dietary NDF, respectively. Rumen inert bulk was added at 25% of pretrial ruminal volume in the form of plastic-coated tennis balls filled with sand to achieve a specific gravity of 1.1 and a total volume of 7.5 L. No fiber level x inert bulk interactions were detected for DMI or NDF intake (P > 0.10), suggesting that DMI was limited to the same extent by physical fill at both levels of dietary fiber. Addition of RIB decreased DMI by an average of 10.7%, which was 65.5 g/L of added bulk. The HF diet depressed DMI by an average of 15.5%, increased NDF intake 27.1%, and reduced ruminal NDF turnover time by 21.0% compared to the LF diet (P < 0.01), with no effect on ruminal volume or amount of NDF in the rumen (P > 0.10). Addition of RIB also reduced ruminal NDF turnover time and amount of NDF in the rumen (11.8% and 20.7%, respectively; P < 0.01), with no change in ruminal digesta volume (P > 0.10). The HF treatment decreased digestibility of DM and GE (5.5 and 5.7%, respectively; P < 0.01) but increased NDF digestibility (10.4%; P < 0.01) compared to LF. Rumen inert bulk had no effect on digestibility of DM, NDF, or GE (P > 0.10). The lack of reduction in digesta volume with addition of inert fill suggests that DMI of light-weight steers receiving corn silage-based diets within a wide range of NDF concentrations was not regulated by ruminal distension alone.

Animal Feed↗
PubMed2002

NutriDense and waxy corn hybrids: effects on site and extent of disappearance of nutrients in sheep.

Six Suffolk wether lambs (40.9+/-1.05 kg) surgically fitted with ruminal and double-L-shaped duodenal and ileal cannulas were used in a 3 x 6 Latin rectangle design to investigate the effects of three corn hybrids on site and extent of disappearance of nutrients and rumen characteristics. Treatments were 1) a conventional yellow dent corn (CC) diet, 2) a NutriDense corn (NC) diet, and 3) a waxy corn (WC) diet. Diets consisted of 43.9% cracked corn grain, 39.1% cottonseed hulls, 15.3% soybean meal, 1.49% vitamin and mineral supplement, and 0.21% chromic oxide (DM basis). Lambs were fed twice daily at 1.8 x NEm requirement. Ruminal pH, fluid dilution rate, volume, NH3 N, and total VFA concentrations, as well as molar proportions of isobutyrate, butyrate, and valerate, were similar (P > 0.10) among dietary treatments. Apparent and true OM disappearances (g/d and percentage of OM intake) from the stomach were similar (P > 0.10) among dietary treatments. Apparent OM disappearance (percentage of duodenal OM flow) from the small intestine was higher (P < 0.05) for the WC than for the NC treatment. Apparent total tract OM disappearance (percentage of OM intake) was also similar (P > 0.10) among dietary treatments. Total apparent and true starch disappearances (g/d) from the stomach were higher (P < 0.05) for the WC diet than for the CC and NC diets. However, apparent and true starch disappearances from stomach as percentage of starch intake were higher (P < 0.05) for the WC diet than for the CC diet. Starch disappearance (g/d) from the small intestine was higher (P < 0.05) for the CC diet than for the WC diet; however, apparent starch disappearance (percentages of duodenal starch flow) from the small intestine was higher (P < 0.05) for the WC diet than for the CC diet. Duodenal flows of total N, bacterial N, NH3 N, and non-NH3 nonbacterial N (g/d) and efficiencies of bacterial protein production (g of bacterial N/kg of true or apparent OM disappearing in the stomach) were similar (P > 0.10) among dietary treatments. Apparent and true N disappearance from stomach (g/d) and apparent total tract N disappearance (percentage of N intake) were also similar (P > 0.10) among dietary treatments. Total N disappearance from the hindgut was -0.81, -1.06, and -1.46 g/d for CC, NC, and WC, respectively, and was different (P < 0.05) between CC and WC diets. Results indicated that higher ruminal starch disappearance in WC did not increase microbial N production or efficiency when compared to CC.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Stockpiled forage or limit-fed corn as alternatives to hay for gestating and lactating beef cows.

In Exp. 1, 31, 24, and 17 mature, pregnant Simmental x Angus cows (initial BW = 662.0 +/- 10.4 kg) in each of 3 yr were used to determine the efficacy of stockpiled orchardgrass, limit-fed corn, or ad libitum hay for maintaining cows in mid- to late gestation, respectively. In Exp. 2, 24 mature, pregnant crossbred cows (initial BW = 677.7 +/- 9.4 kg) per treatment in each of 3 yr were used to determine the efficacy of stockpiled orchardgrass, limit-fed corn, or ad libitum hay for maintaining cows in late gestation and early lactation, respectively. Each year, cows were assigned to treatment by BW. From November to February or from January to April, respectively, nutritional needs for mid- to late gestation (Exp. 1) or late gestation and early lactation (Exp. 2) were met either by 1) rotating cows on approximately 15.2 or 21.7 ha of predominantly orchardgrass pasture, set aside and fertilized in late August, 2) limit-feeding approximately 5.8 kg of whole shelled corn, 1.1 kg of a pelleted supplement, and 1.2 kg of hay daily, or 3) ad libitum feeding of round-baled hay. During extreme weather conditions, cows grazing stockpiled orchardgrass were limit-fed a grain-based diet. Postcalving weight (P < 0.10) was greatest for limit-fed cows in Exp. 1 and lowest for cows grazed on stockpiled orchardgrass; cows given ad libitum access to hay were intermediate in weight and did not differ from cows limit-fed or cows grazed on stockpiled orchardgrass (641.8, 657.4, and 634.0 kg, respectively). Calving date, calf birth and weaning weight, and conception rate did not differ among treatments (P > 0.15) in Exp. 1. In Exp. 2, weight at weaning did not differ among treatments (P > 0.17); however, postcalving weight (P < 0.01) was greatest for cows given ad libitum access to hay, intermediate for limit-fed cows, and lowest for cows grazed on stockpiled orchardgrass (674.8, 652.4, and 624.5 kg). Body condition score at any time point did not differ among treatments (P > 0.38), nor did calving date, calf birth and weaning weights, and conception rate (P > 0.12). Because of the few differences in cow performance, selection of energy sources for beef cows can be made based on economics. The cost to feed a cow hay in early to mid-gestation was nearly double that of limit-feeding the corn-based diet or grazing stockpiled orchardgrass. Because of lower quality pastures, the cost to graze cows on stockpiled orchardgrass during late gestation and early lactation was not as cost effective as limit feeding a corn-based diet.

Animal Feed↗
PubMed2003

Combinations of alfalfa hay and wet corn gluten feed in limit-fed growing diets for beef cattle.

Two experiments were conducted to evaluate the effects of alfalfa hay (AH) and wet corn gluten feed (WCGF) combinations on ADG and gain efficiency of cattle limit-fed growing diets. In Exp. 1, crossbred beef steers (n = 220; initial BW = 262 kg) were limit-fed diets consisting of steam-flaked corn and 40% WCGF (DM basis) with 0, 10, or 20% ground AH (0AH, 10AH, and 20AH, respectively). A fourth diet containing 20% ground AH and steam-flaked corn served as a control. All diets were fed once daily at 1.8% of BW (DM basis). Growing period ADG, gain efficiency, and dietary NE calculated from performance data decreased linearly (P < 0.01) with addition of AH to diets containing WCGF. Rate of DMI increased linearly (P < 0.05) with AH addition to diets containing WCGF. Following the growing period, steers were finished on a common diet offered ad libitum. Gain efficiencies during the finishing period were higher (P < 0.05) for steers fed the 20AH diet than for steers fed the control diet. In Exp. 2, crossbred beef heifers (n = 339; initial BW = 277 kg) were limit-fed diets containing steam-flaked corn with 10, 20, or 30% ground AH and 0, 40, or 68% WCGF in a 3 x 3 factorial arrangement, fed once daily at 1.6% of BW (DM basis). An AH x WCGF interaction occurred (P < 0.05) for growing period ADG and gain efficiency. Increasing AH or WCGF decreased cattle ADG, gain efficiency, and dietary NE with the exception of heifers fed 30AH/40WCGF, which had ADG that did not differ (P > 0.10) from that of heifers fed 20AH/0WCGF or 30AH/0WCGF, and which had greater gain efficiencies (P < 0.05) than heifers fed 30AH/0WCGF. Rate of DMI increased linearly (P < 0.01) with increasing AH and decreased linearly (P < 0.01) with increasing WCGF. Heifers were finished on diets containing 33% WCGF with 0 or 0.5% added urea (DM basis) offered ad libitum. Increasing WCGF in growing diets tended (linear, P < 0.10) to increase finishing ADG and gain efficiency, whereas increasing AH decreased (linear, P < 0.05) kidney, pelvic, and heart fat, and the percentage of carcasses grading USDA Prime. Urea tended to increase ADG (P < 0.10), but decreased (P < 0.04) the percentage of carcasses grading USDA Choice. Results suggest that the value of WCGF relative to steam-flaked corn in limit-fed growing diets might be improved in diets containing 30% AH relative to diets containing 10 or 20% AH.

Animal Feed↗
PubMed2004

Effects of wet corn gluten feed and intake level on diet digestibility and ruminal passage rate in steers.

Twelve ruminally cannulated Jersey steers (BW = 534 kg) were used in an incomplete Latin square design experiment with a 2 x 2 factorial arrangement of treatments to determine the effects of wet corn gluten feed (WCGF) and total DMI level on diet digestibility and ruminal passage rate. Treatments consisted of diets formulated to contain (DM basis) steam-flaked corn, 20% coarsely ground alfalfa hay, and either 0 or 40% WCGF offered once daily for ad libitum consumption or limited to 1.6% of BW (DM basis). Two consecutive 24-d periods were used, each consisting of 18 d for adaptation, 4 d for collection, and a 2-d in situ period. Rumens of all steers were evacuated once daily at 0, 4, 8, and 12 h after feeding. Chromic oxide (10 g/[steer*d]) was fed as a digestibility marker, and steers were pulse-dosed with Yb-labeled alfalfa hay to measure ruminal particulate passage rate. Dacron bags containing 5 g of steam-flaked corn, WCGF, or ground (2-mm screen) alfalfa hay were placed into the rumens of all steers and removed after 3, 6, 12, or 48 h. Wet corn gluten feed increased percent apparent total-tract digestion of OM (P < 0.01), NDF (P < 0.01), and starch (P < 0.03), decreased (P < 0.01) ruminal total VFA concentration, increased (P < 0.01) ruminal NH3 concentration, and increased (P < 0.01) ruminal pH. Wet corn gluten feed also increased (P < 0.01) ruminal passage rate of Yb. Limit feeding decreased (P < 0.01) percent apparent total-tract digestion of both OM and NDF, ruminal total VFA concentration (P < 0.01), and ruminal fill (P < 0.01), but increased (P < 0.01) ruminal NH3 concentration. Apparent total-tract digestion of starch was not affected (P = 0.70) by level of DMI. A DMI level x hour interaction (P < 0.01) occurred for ruminal pH. Limit feeding increased ruminal pH before and 12 h after feeding, but decreased ruminal pH 4 h after feeding compared with diets offered ad libitum. A diet x DMI level interaction (P < 0.02) occurred for in situ degradation of alfalfa hay, with dietary addition of WCGF increasing (P < 0.02) the extent of in situ alfalfa hay degradation in steers fed for ad libitum consumption. This study suggests that WCGF increases OM and NDF digestion, and that limit feeding diets once daily might depress OM and NDF digestion, possibly due to decreased stability of the ruminal environment.

Animal Feed↗
PubMed2005

Effects of dried full-fat corn germ and vitamin E on growth performance and carcass characteristics of finishing cattle.

Two experiments were conducted to evaluate dried full-fat corn germ (GERM) as a supplemental fat source in cattle finishing diets. In Exp. 1, 24 pens totaling 358 crossbred beef steers with an initial BW of 319 kg were allowed ad libitum access to diets containing dry-rolled corn, 35% wet corn gluten feed, and 0, 5, 10, or 15% GERM on a DM basis. Increasing GERM decreased (linear; P < 0.02) DMI and increased (quadratic; P < 0.02) ADG. Steers fed 10% GERM had the greatest ADG (quadratic; P < 0.02) and G:F (quadratic; P < 0.05). The addition of GERM increased (linear; P < 0.05) fat thickness, KPH, and the percentage of USDA Yield Grade 4 carcasses (quadratic; P < 0.03), with steers fed 15% GERM having the greatest percentage of USDA Yield Grade 4 carcasses. In Exp. 2, 48 pens totaling 888 crossbred beef heifers with an initial BW of 380 kg were allowed ad libitum access to diets containing steam-flaked corn, 35% wet corn gluten feed, and either no added fat (control), 4% tallow (TALLOW), or 10 or 15% GERM on a DM basis, with or without 224 IU of added vitamin E/kg of diet DM. No fat x vitamin E (P > or = 0.08) interactions were detected. Fat addition, regardless of source, decreased (P < 0.01) DMI, marbling score, and the number of carcasses grading USDA Choice. Among heifers fed finishing diets containing TALLOW or 10% GERM, supplemental fat source did not affect DMI (P = 0.76), ADG (P = 0.54), G:F (P = 0.62), or carcass characteristics (P > or = 0.06). Increasing GERM decreased DMI (linear; P < 0.01) and ADG (quadratic; P < 0.02), with ADG by heifers fed 10% GERM slightly greater than those fed control but least for heifers fed 15% GERM. Increasing GERM improved (quadratic; P < 0.03) G:F of heifers, with heifers fed 10% GERM having the greatest G:F. Increasing GERM decreased HCW (linear; P < 0.02), marbling score (linear; P < 0.01), and the percentage of carcasses grading USDA Choice (linear; P < 0.01). The addition of vitamin E increased (P < 0.04) the percentage of carcasses grading USDA Select and decreased (P < 0.01) the percentage of carcasses grading USDA Standard. These data suggest that GERM can serve as a supplemental fat source in cattle finishing diets, and that the effect of vitamin E did not depend on source or concentration of supplemental fat.

Animal Feed↗
PubMed2006

Growth performance and carcass characteristics of pigs fed short-season corn hybrids.

An experiment was conducted to determine growth performance, carcass characteristics, and fat quality of growing-finishing pigs fed diets based on short-season corn hybrids. Twenty-four individually housed, Cotswold, growing pigs with an initial BW of 41.4 (SD = 1.4) kg were blocked by BW and sex and randomly allotted from within block to 1 of 3 diets to give 8 replicate pigs per diet. Experimental diets consisted of a control based on barley and 2 diets based on corn as the main energy sources. A 3-phase feeding program for 20 to 50 kg (phase I), 50 to 80 kg (phase II), and 80 to 110 kg (phase III) of BW was used. Diets for each phase contained approximately 3.5 Mcal/kg of DE, with total lysine of 0.95, 0.75, and 0.64% in phase I, II, and III diets, respectively. Average daily gain, ADFI, and G:F were monitored weekly during each phase. Pigs were slaughtered after reaching a minimum BW of 100 kg to determine carcass characteristics. There were no effects of diet on ADG, ADFI, and G:F (0.45 +/- 0.02, 0.34 +/- 0.02, and 0.31 +/- 0.02 for phase I, II, and III, respectively). Carcass length, dressing percent, LM area, loin depth, backfat thickness, belly firmness, and L*, b*, and a* fat color were not different across dietary treatments. Pigs fed one corn variety had no differences in fatty acid profile with barley-fed pigs, whereas those fed the other variety of corn had a greater (P < 0.05) concentration of PUFA in their backfat. The results indicate that growth performance, carcass characteristics, and fat quality of pigs fed diets based on short-season corn hybrids and those fed the barley-based diet were not different.

Adipose Tissue↗
PubMed2006

Influence of corn hybrid traits on digestibility and the efficiency of gain in feedlot cattle.

Two experiments were conducted to determine the influence of chemical and physical corn kernel traits on digestibility and feedlot cattle performance. Seven commercially available corn hybrids representing a range in kernel traits were evaluated for a variety of chemical and physical traits that included test weight, 1,000-grain weight, kernel size, starch, CP, amylose, Stenvert Hardness tests (kernel hardness traits), tangential abrasive dehulling device loss, 12-h in vitro starch disappearance, and rate and extent of in situ DM disappearance. Differences among hybrids existed for all physical kernel traits measured. In Exp. 1, 224 steers in 28 pens were fed the same hybrids for 167 d in a completely randomized design. All diets were formulated to have 12.5% CP and contained 66% dry-rolled corn (DM basis). There were no differences (P >0.20) among corn hybrids for DMI, ADG, or carcass characteristics. However, efficiency of gain (G:F) was influenced by hybrid (P < 0.01) with a difference of 9.5% from the least to the most efficient. In Exp. 2, 7 ruminally cannulated heifers were used in a 7 x 7 Latin square design to determine the effects of these hybrids on nutrient digestibility, VFA concentrations, and ruminal pH. Total-tract OM and starch digestibilities were not different (P >0.15) among hybrids and averaged 77.9 and 95.1%, respectively. Differences (P < 0.05) among hybrids existed for ruminal propionate concentration and the acetate to propionate ratio. Kernel hardness traits correlated (P < 0.05) with G:F were 1,000-grain weight (r = -0.81), Stenvert time to grind (r = -0.83), and the proportion of Stenvert soft to coarse particle height (r = 0.83). Propionate concentration was not correlated (r = 0.45) with G:F but was correlated (P = 0.02) to the Stenvert time to grind (r = -0.83). Cattle fed dry-rolled corn hybrids with greater proportions of soft endosperm had greater concentrations of propionate and gained more efficiently than cattle fed hybrids with a harder endosperm. Selecting for these softer kernel traits may improve the efficiency of gain in feedlot cattle.

Animal Feed↗
PubMed1980

Effect of ensiling whole plant corn on voluntary intake, rumen fermentation, retention time and rate of digestion in steers.

The study was designed to determine whether products of fermentation in corn silage could limit its voluntary intake. Six rumen-cannulated Hereford steers were assigned randomly to diets of corn silage (CS) and dried corn forage reconstituted either with water (DC + W) or with extracts from corn silage (DC + CSE) according to a crossover design with three experimental periods. During each period, steers were fed ad libitum for 18 days and then restricted to 65 g DM/kg BW.75 for another 13 days. During the restricted feeding period, measures of rumen fermentation were made, and mean retention time (MRT) of rumen digesta was estimated after a single injection of the liquid and solid phase markers, 51Cr-EDTA and 103Ru-Phenanthroline complex (103Ru-P), respectively. Daily voluntary intake of DM (g/kg BW.75) for diet DC + W (80.2) was not diffferent (P greater than .05) from that for CS (89.7) but was significantly lower than that for DC + CSE (93.5). The corresponding estimates of MRT were 16.1, 14.1 and 17.4 hr (SEM +/- .5) for 51Cr-EDTA and 23.2, 23.9 and 24.3 hr (SEM +/- .7) for 103Ru-P. Measurements of osmolality, pH and VFA concentrations in rumen fluid were not related to daily DM intake. A study of rate of DM digestion, conducted by the rumen bag technique with samples of freeze-dried corn silage residue obtained after liquid extraction, yielded rate constants (hr-1) of .039 +/- .0030, .055 +/- .0028, and .0030 when steers were fed CS, DC + W and DC + CSE, respectively.

Animal Feed↗
PubMed1982

Ruminal VFA production with steers fed whole or ground corn grain.

Ruminal production and interchange rates of volatile fatty acids (VFA) were measured for steers fed corn grain in the whole or ground form. Liquid turnover rate was 29% greater (P less than .10) with steers fed the corn in the whole form. On a molar basis (mol/100 mol), ruminal concentrations of propionate were lower while those of butyrate, 3-methyl butyrate, valerate and caproate were greater with whole than with ground corn diets. Acid production differences followed similar trends with de novo production of butyrate being seven times greater and irreversible butyrate loss three times greater with whole than with ground corn diets. Conversion of acetate to butyrate was about 70% greater with whole than with ground corn diets. This conversion far exceeded other VFA exchange rates. Outflow of VFA to the omasum was calculated to equal 20, 25 and 12% of the irreversible loss of acetate, propionate and butyrate, respectively. Ruminal output of energy as VFA from the rumen equaled 60 and 43% of consumed energy with the whole and ground grain diets, respectively. Production rates of VFA were poorly correlated with ruminal concentrations except for butyrate. Less than 10% of the labeled carbon from acetate and butyrate was detected in plasma glucose, but the transfer coefficient from propionate uncorrected for crossover of label was 59%. Gluconeogenesis from propionate alone exceeded literature estimates for basal glucose requirements of nonlactating ruminants.

Acetates↗
PubMed1985

The nutritional value of normal and high lysine corns for weanling and growing-finishing swine when fed at four lysine levels.

One-hundred-ninety-two weanling pigs from two separate trials, (initial weight 6.0 and 5.6 kg) and 400 growing-finishing pigs (initial weight 17 kg) were fed normal and high lysine corn diets containing four levels of lysine in a 2 X 4 factorial arrangement. Crossbred (Large White X Landrace X Duroc) pigs were used in all experiments. The objectives of the experiments were to (1) compare normal and high lysine corn when fed at different lysine levels, (2) determine the lysine requirements for the three stages of growth and (3) evaluate the effect of protein level on the lysine requirement. All diets were balanced on a lysine basis. The results indicated that both weanling and growing-finishing pig performance and final carcass composition were similar for pigs fed normal or high lysine corn diets balanced on a lysine basis. Weanling pigs from 5 to 14 kg required at least 1.10% lysine. Based on changes in body weight gain and feed efficiency, the lysine requirement of growing pigs (17 to 54 kg) was .70%, and that of finishing pigs (54 to 101 kg) was .50%. However, based on lean tissue growth rate (as reflected by longissimus muscle area and percentage of lean in the carcass) the requirement was at least .75% during the growing stage and .60% during the finishing stage. The reduced protein level (2% lower) of the high lysine corn diets did not reduce the lysine required by pigs compared with those fed normal corn.

Animal Feed↗
PubMed1987

Apparent digestibility of amino acids, gross energy and starch in corn, sorghum, wheat, barley, oat groats and wheat middlings for growing pigs.

Apparent nutrient digestibilities of yellow-dent corn, low-tannin sorghum, hard red winter wheat, barley, oat groats and wheat middlings were determined near the end of the small intestine and over the total digestive tract of growing pigs. Gross energy digestibilities for corn, sorghum and oat groats were similar; wheat had a slightly lower (P less than .05) digestibility, followed by barley (P less than .05), with wheat middlings being the least (P less than .05) digestible. About 7% of the gross energy in corn, sorghum, wheat and oat groats was digested in the large intestine, compared with 11% for barley and 17% for wheat middlings. The starch in all products was essentially 100% digestible by the end of the small intestine. Ileal amino acid digestibilities tended to be highest for wheat and oat groats, followed by corn, sorghum, barley and wheat middlings. The range in ileal digestibilities was 73.8 (sorghum) to 84.2% (wheat) for lysine, 69.6 (corn) to 81.4% (wheat) for tryptophan and 63.4 (wheat middlings) to 77.9% (oat groats) for threonine. Amino acid digestibilities determined over the total tract were generally higher than ileal digestibilities; however, values for lysine, methionine and phenylalanine were generally lower, indicating a net synthesis of these amino acids in the large intestine.

Amino Acids↗
PubMed1987

Evaluation of corn fiber, cottonseed hulls, oat hulls and soybean hulls as roughage sources for ruminants.

An in situ trial (randomized complete block design) using cows, and a site and extent of digestion trial (Latin square design) using sheep were conducted to study the potential of corn fiber (CF), cottonseed hulls (CSH), oat hulls (OH) and soybean hulls (SH) as roughage sources for ruminants. Two feedlot trials with steers and one with lambs (completely randomized design with factorial arrangements of treatments) were conducted to study the potential of CF and SH as energy supplements relative to corn. In situ rate of ruminal dry matter (DM) disappearance (3 to 36 h) and extent of DM disappearance (36 h) indicated that CF and SH were more fermentable in the rumen compared with OH or CSH, with SH being the most fermentable. Total tract digestibilities of DM, organic matter (OM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were above 70% for sheep fed CF and SH diets, and were 50% or less for sheep fed OH and CSH diets. A ranking of by-products in terms of nutritive value followed the trend: CF greater than SH greater than OH greater than CSH. Lamb feedlot trial data showed that CF was of similar nutritive value to corn and of higher nutritive value than SH at the 50% level of supplementation. Corn-fed lambs responded better than CF- or SH-fed lambs at the 70% level of supplementation. Data from steer feedlot trials showed that CF was of similar quality to corn and of higher quality than SH. Dramatic differences exist in by-product feed utilization by ruminants. All by-products tested appeared to have some usefulness as dietary components.

Animal Feed↗
PubMed1989

Voluntary feed intake, acid-base balance and partitioning of urinary nitrogen in lambs fed corn silage with added sodium bicarbonate or sodium sesquicarbonate.

An experiment with growing lambs was designed to test the hypothesis that alterations in blood acid-base status would influence intake of corn silage. Six wethers (29 kg) were fed a diet of corn silage (36% DM, 8% CP) supplemented with 1.25% urea and .2% sulfur. At feeding time, sodium bicarbonate (NaHCO3) and sodium sesquicarbonate (NaSC) were added to the silage at levels of 0, 2% or 4% of diet DM. The treatments were arranged as a 2 x 3 factorial, and the study was conducted as a 6 x 4 incomplete latin square with four 17-d periods. Voluntary intake of OM was not different (P greater than .05) between NaHCO3 (1,008 g/d) and NaSC (1,041 g/d). There was no significant interaction between type of buffer (NaHCO3 or NaSC) and level of buffer on any of the variables measured. The progressive increase in buffer load did not alter feed intake (P greater than .05), although there was a quadratic response (P less than .05) in urine pH and a linear increase (P less than .01) in blood HCO3- 2 h after feeding. There was no evidence that lambs fed corn silage experienced metabolic acid stress. Urinary excretion of ammonia and urea were indicative of changes, although not pronounced, in ammoniuria and ureapoiesis in response to bicarbonate loading. This study implies that corn silage imposes no "acid stress" on lambs and, consequently, that there is no nutritional benefit in adding buffers to corn silage for sheep.

Acid-Base Equilibrium↗
PubMed1984

Evaluation of the mutagenic potential of corn (Zea mays L.) grown in untreated and atrazine (AAtrex) treated soil in the field.

Bacterial assays using extracts from field corn plants (harvested at one month, silage and mature stages) do not indicate that soil treatment with atrazine, at its maximum use rate, alters the endogenous mutagens present in these extracts, nor that atrazine itself is degraded to mutagenic products. Extracts of corn grown in soil treated with AAtrex were equally mutagenic with those of corn grown in untreated soil when tested in Salmonella typhimurium TA-100 by a reversion assay or in Salmonella typhimurium TM-677 in a forward mutation assay. Higher concentrations of histidine in corn grown in AAtrex treated soil may interfere with the reversion assay, but do not affect the forward mutation assay. The nature of the agent(s) responsible for the positive response was not determined. The mutagenicity may be due to natural plant constituents, an artifact of the sample preparation, or mycotoxins from some unrecognized plant infection. The experimental results in these field studies do not show that atrazine is degraded or metabolized by corn plants to mutagens in this sensitive bacterial assay.

Atrazine↗