Copyright (c) 2013 University of Nebraska - Lincoln All rights reserved. http://digitalcommons.unl.edu/animalscifacpub Recent documents in Faculty Papers and Publications in Animal Science en-us Thu, 02 May 2013 12:37:04 PDT 3600 http://digitalcommons.unl.edu/animalscifacpub/785 http://digitalcommons.unl.edu/animalscifacpub/785 Wed, 10 Oct 2012 14:30:56 PDT The objective of this study was to evaluate the effect of parentage misidentification on estimation of genetic parameters for the Italian buffalo population for milk yield from 45,194 lactation records of 23,104 Italian buffalo cows. Animals were grouped into 10 data sets in which sires and dams were DNA identified, or reported from the pedigree, or unknown. A derivativefree restricted maximum likelihood method was used to estimate components of variance with a repeatability model. The model contained age at calving nested within parity and days from calving to conception as linear covariates, herd-year-seasons as fixed effects, and additive genetic, permanent environmental, and temporary environmental effects as random effects. Estimates of heritability (±SE) ranged from 0.00 ± 0.099 (sires and dams as reported in the pedigree) to 0.39 ± 0.094 (sires DNA identified and dams as reported in the pedigree). When identification of sires was as reported in the pedigree, estimates of heritability were close to zero. These small estimates indicate that a large proportion of reported paternity is incorrect. When sires are unknown and dams are DNA identified, the proportion of variance due to sires seems to be captured in the estimate of permanent environmental variance as a fraction of phenotypic variance. Therefore, as heritability decreased, permanent environmental variance increased about the same amount. Data sets with dams identified from pedigree and sires DNA identified showed the largest estimate of heritability (0.39), which was essentially the same as when dams were DNA identified (0.38). This result supports that most dams are correctly reported from the pedigree. Genetic progress should be much greater with bulls DNA identified because of greater heritability, but without artificial insemination and progeny testing, progress would be slow and would depend mostly on selection of sires based on dam estimated breeding values. Implementation of artificial insemination programs and DNA testing to identify sires are the keys for increasing genetic progress in the Italian buffalo population.

]]> Emanuela Parlato et al. http://digitalcommons.unl.edu/animalscifacpub/784 http://digitalcommons.unl.edu/animalscifacpub/784 Mon, 27 Aug 2012 09:55:41 PDT Wet distillers grains contain approximately 65% moisture. A partially dried product (modified distillers grains plus solubles; MDGS) contains about 50% moisture. However, both have similar nutrient composition on a dry matter basis. The objective of this study was to investigate the effects of finishing diets varying in concentration of MDGS on marbling attributes, proximate composition, and fatty acid profile of beef. Yearling steers (n = 268) were randomly allotted to 36 pens which were assigned randomly to 0, 10, 20, 30, 40 and 50% MDGS (DM basis) and fed for 176 d prior harvest. Forty-eight h postmortem marbling score, marbling texture, and marbling distribution were assessed by a USDA grader and one ribeye slice (longissimus thoracis) 7 mm thick was collected from each carcass for proximate and fatty acid analysis. Treatments did not significantly alter marbling score or marbling distribution (P ≤ 0.05). USDA Choice slices had coarser marbling texture when compared to USDA Select. Although dietary treatment affected marbling texture no consistent pattern was evident. Diets did not influence fat content, moisture, or ash of the ribeye (P ≥ 0.05). For treatments 0, 10, 30, 40 and 50% there were positive linear relationships between marbling score and fat percentage in the ribeye (P ≤ 0.05) and all slopes were similar (P = 0.45). Feeding MDGS linearly increased stearic, linoelaidic, linoleic, linolenic, PUFA and n-6 fatty acids. As levels of MDGS increased, linear decreases were observed in all n- 7 fatty acids and cubic relationships were detected for the 18:1 trans isomers (trans-6-8-Octadecenoic acid, 6-8t, elaidic acid, 9t, trans-10-Octadecenoic acid, 10t, and trans vaccenic, 11t). No effects were observed for saturated fatty acids containing 6 to 14 carbons. Feeding MDGS resulted in increased PUFA, trans, and Omega 6 fatty acids, minimal effects on marbling texture, and no effects on the relationship of marbling to intramuscular fat content relationship.

]]> A.S. Mello Jr. et al. http://digitalcommons.unl.edu/animalscifacpub/783 http://digitalcommons.unl.edu/animalscifacpub/783 Mon, 27 Aug 2012 09:48:37 PDT Ninety-four, calf-fed crossbred steers were randomly allocated to three different dietary treatments (0%, 15% or 30% wet distillers grains plus solubles - WDGS – DM basis) and fed for 167 d to test the influence of different levels of WDGS on quality attributes of beef. At 48 h postmortem, marbling score, marbling texture, and marbling distribution were assessed by a USDA grader. After grading, one ribeye slice (Longissimus thoracis) about 7 mm thick was excised from each carcass, trimmed of subcutaneous fat, and analyzed for fatty acid profile and lipid content. At 7 d postmortem, 48 top blades (Infraspinatus), strip loins (Longissimus lumborum) and tenderloins (Poas major) (16 per treatment) were removed from shoulder clods and short loins and two steaks were obtained for measurement of mineral content, fatty acid profile (except strip loins), trained sensory analysis, objective color and lipid oxidation. Finishing diet did not influence the content of total lipid (P = 0.19) or marbling, marbling texture, or marbling distribution (P = 0.46, P = 0.84 and P = 0.40, respectively). Feeding WDGS created a linear increase (P < 0.01) of PUFA in all three muscles (Longissimus thoracis showed: 4.90, 5.91, and 6.23 % for 0, 15 and 30%, respectively). Similar responses were observed for 18:2(n-6) and total omega 6 fatty acids. Conversely, lower proportions of 18:1(n-7) fatty acid were observed in beef from animals fed 30% WDGS (P < 0.01). Total trans fatty acids increased linearly in strip loin and top blade steaks (P < 0.01) whereas proportions of 16:0 and 14:1(n-5) fatty acids decreased in all muscles (P < 0.01) as levels of WDGS increased. Diet did not affect mineral content of top blades or strip loins. For tenderloin steaks, sulfur concentration was lower when 30% of WDGS was fed (P = 0.05). No effects on sensory attributes and Warner Bratzler shear force were observed (P ≥ 0.50), except a minimal effect on strip loin juiciness (5.32, 4.86, and 5.52 for 0, 15, and 30%, respectively; P = 0.02). Top blade and tenderloin steaks from cattle fed 30% WDGS were significantly less red (lower a* values) on day 3 of simulated retail display (P < 0.04). Inclusion of 30% WDGS in the diet resulted in higher levels of oxidation after 7 d of retail display for top blade and strip loin steaks (P < 0.01). Feeding WDGS to calf-fed steers altered fatty acid profile, increased oxidation and decreased color stability during retail display.

]]> A. S. Mello Jr. et al. http://digitalcommons.unl.edu/animalscifacpub/782 http://digitalcommons.unl.edu/animalscifacpub/782 Fri, 01 Jun 2012 08:51:47 PDT Three-hundred sixty calf-fed steers (BW = 318 ± 15 kg) were used in a completely randomized design to evaluate corn processing methods in finishing diets containing wet distillers grains plus solubles (WDGS). Whole corn (WC) was compared with corn processed by different methods, consisting of dryrolled corn (DRC), high-moisture corn (HMC), a 1:1 DRC:HMC combination (DM basis), steam-flaked corn (SFC), and finely-ground corn (FGC). The SFC with a flake density of 0.33 kg/L was obtained from a commercial feedlot. Basal dietary ingredients consisted of ground alfalfa hay (5.6% of DM) and dry supplement (3.0% of DM), with the balance being WDGS (30% of DM) and corn (61.4% of DM). Final BW and ADG were greater (P < 0.05) for the cattle fed DRC (1.84 kg/d) compared with cattle fed FGC (1.53 kg/d), SFC (1.63 kg/d), and WC (1.75 kg/d), but was not different (P = 0.11) from cattle fed DRC:HMC (1.78 kg/d). Cattle fed HMC (0.185) had greater (P < 0.05) G:F compared with cattle fed FGC (0.166), SFC (0.176), and WC (0.166). No differences (P > 0.30) were detected between cattle fed HMC and DRC:HMC for ADG and G:F; however, cattle fed DRC tended to have greater (P = 0.08) ADG, yet lower (P = 0.08) G:F than cattle fed HMC. Carcass characteristics reflected performance. These data indicate that steam flaked and finely ground corn processing methods, or no processing, are not as effective as high-moisture or dry-rolled corn processing methods in finishing diets containing 30% WDGS.

]]> K. J. Vander Pol et al. http://digitalcommons.unl.edu/animalscifacpub/781 http://digitalcommons.unl.edu/animalscifacpub/781 Fri, 01 Jun 2012 08:43:38 PDT Recently, high prices have driven producers to replace corn partially or totally with more affordable ingredients. A total of 1,256 DNA-validated progeny from Angus (n = 241), Simmental (n = 599), Simmental × Angus (SA; n = 296), and 75% Simmental (75S; n = 120) sires were used to evaluate the effects of feedlot nutrition and sire breed on the performance, carcass characteristics, and rates of ultrasound backfat and marbling deposition in feedlot cattle. Diets included corn or a corn co-product: dried distillers grains with solubles (DDGS), fresh wet distillers grains, wet corn gluten feed, stored wet distillers grains, or dried corn gluten feed. Dry matter intake for steers fed the co-product diets increased by approximately 8% compared with that of steers fed the high-corn diet. Steers fed the corn co-product diets had greater (P < 0.05) ADG. Steers fed DDGS, wet distillers grains, and wet or dried corn gluten feed deposited approximately 0.02 mm/d more (P < 0.05) backfat than steers fed the high-corn diet. The greatest (P < 0.05) rate of intramuscular fat deposition was in steers fed 40% DDGS. Steers sired by Angus bulls had greater (P < 0.05) DMI than the progeny of Simmental and SA sires. Backfat was greater (P < 0.05) in the progeny of Angus bulls than in the progeny of Simmental, SA, and 75S sires. Steers sired by Angus bulls had the greatest (P < 0.05) marbling score. The greatest rate (P < 0.05) of backfat deposition was observed in the progeny of Angus sires. Steers sired by Angus and SA bulls had the greatest rates (P < 0.05) of marbling deposition. The progeny of Simmental, Angus, and 75S were similar (P > 0.05) in the amount of marbling deposited per centimeter of backfat (184 marbling score units/cm of backfat). This study indicates that co-product diets had less effect on performance and carcass quality than did breed of sire.

]]> C. O. Trejo et al. http://digitalcommons.unl.edu/animalscifacpub/780 http://digitalcommons.unl.edu/animalscifacpub/780 Fri, 01 Jun 2012 08:40:36 PDT Calving date for 120 cows in the Nebraska Sandhills was changed from the traditional calving season beginning March 15 (d 75) to one beginning June 15 (d 167) to match increased nutrient needs for lactating cows to immature grazed forages that are high in protein and energy. The hypotheses being tested were that 1) less hay and purchased feeds would be required, 2) production costs would be reduced, and 3) net returns would be greater for June-calving cows compared with their March-calving counterparts. All steer calves from 75 March-calving cows were moved to a feedlot within 60 d of weaning (March calf-feds). Half the steer calves from the 120 June-calving herd were moved within 60 d of weaning to a feedlot to be finished (June calf-feds) and the other half were moved to a feedlot in September after summer grazing of Sandhills rangeland (June yearlings). Half of the June-calving cows were bred on sub-irrigated regrowth (Meadow) and half on upland range. Data on 4 consecutive calf crops were collected through harvest with an additional year collected to feedlot placement. Results showed that fed hay was reduced from 1.79 to 0.10 metric tons per cow annually for the June-calving system. Cost and return analyses were conducted by production phases on steer calves. Production costs for both June-calving groups were less and net returns higher when compared with the March-calved group. The highest net return for a calf group was for the June yearlings from cows bred on subirrigated regrowth.

]]> M. C. Stockton et al. http://digitalcommons.unl.edu/animalscifacpub/779 http://digitalcommons.unl.edu/animalscifacpub/779 Fri, 01 Jun 2012 08:37:37 PDT Three experiments evaluated the influence of supplementation frequency of distillers dried grains plus solubles (DDGS) on forage digestibility (Exp. 1) and growth of yearling heifers (Exp. 2) and steers (Exp. 3). In Exp. 1, 6 steers (371 ± 30 kg) were used in a replicated 3 × 3 Latin square design with three 21-d periods. Treatments were DDGS fed at 16.7% of the diet (DM) either 1) daily, 2) every other day, or 3) every third day. In Exp. 2, 48 heifers (193 ± 20 kg) were fed hay and supplemented with the daily equivalent of 1.3 kg/ heifer of DDGS, either 3 or 6 d/wk. In Exp. 3, 48 steers were assigned to replicated supplementation groups. Treatments were 1) hay and supplement fed 6 d/wk in a dry lot (control); 2) native winter range and supplement fed 6 d/wk; 3) native winter range and a DDGS supplement fed 6 d/wk; and 4) native winter range and the same DDGS supplement fed 3 d/wk. In Exp. 1, diet DM (P = 0.06), OM (P = 0.07), and hay NDF (P = 0.03) digestibility decreased linearly as DDGS supplementation frequency decreased. In Exp. 2, heifers fed DDGS 6 d/wk gained more BW (P = 0.01) than heifers fed 3 d/wk. In Exp. 3, steers fed the control diet, native winter range and supplement fed 6 d/wk, and native winter range and DDGS supplement fed 6 d/wk performed similarly, but performance was decreased when steers were fed native winter range and the DDGS supplement 3 d/wk. Improved animal growth may result from more frequent supplementation of DDGS when fed in excess of 15% of the diet.

]]> L. A. Stalker et al. http://digitalcommons.unl.edu/animalscifacpub/778 http://digitalcommons.unl.edu/animalscifacpub/778 Fri, 01 Jun 2012 08:35:47 PDT Two experiments evaluated the inclusion of urea in distillers dried grains supplements. In Exp. 1, 60 Angus heifers (278 ± 16 kg) were individually fed diets consisting of 58% ground corn cobs, 12% sorghum silage, and 30% distillers dried grains (DM basis) in Calan electronic gates. Urea replaced distillers dried grains at 0, 0.4, 0.8, 1.2, or 1.6% of diet DM. In Exp. 2, 48 crossbred heifers were fed meadow hay ad libitum and 1.4 kg (DM) distillers dried grains to which was added either 0 or 45 g urea/ heifer daily. In both experiments, no response in animal weight gain or feed efficiency was observed when urea was added to the diet. Based on retrospective NRC (1996) model analysis of diets, metabolizable protein was in excess of requirements. Lack of response in animal performance may indicate lack of rumen degradable protein deficiency or sufficient N recycling to correct a rumen degradable protein deficiency. These studies indicate adding urea to distillers dried grains is not necessary when fed as a supplement in forage-based diets.

]]> L. A. Stalker et al. http://digitalcommons.unl.edu/animalscifacpub/777 http://digitalcommons.unl.edu/animalscifacpub/777 Fri, 01 Jun 2012 08:30:29 PDT Studies across 5 yr involving 938 British-breed crossbred cattle (372 heifers, 566 steers) were used to evaluate the effects of grazing alternate summer and fall forages on slaughter breakeven cost of various beef production systems. Grazed summer forage combinations included 1) continuous brome, 2)brome and warm-season grasses, 3) brome and alfalfa or sudangrass, 4) brome and a monoculture of red clover, 5) red clover seeded in brome, 6) brome and Native Sandhills range, or 7) Sandhills range only. Grazed fall forages included 1) brome, 2) brome and turnips, 3) brome and rye, or 4) brome and cornstalks. Following grazing, the cattle were finished on a high-concentrate, corn-based finishing diet. The success of a grazing system was measured by slaughter breakeven cost analyses including all costs of production. The most consistent improvement in summer grazing BW gain compared with continuous brome and the most desirable slaughter breakeven costs were observed for cattle grazing brome and warm-season grasses or brome and Sandhills range. Using alfalfa or sudangrass in grazing systems improved (P<0.05) summer gains, but slaughter breakeven costs were greater (P<0.05) compared with cattle grazing brome. Improved summer gains and reduced slaughter breakeven costs when grazing a monoculture of red clover or red clover seeded in brome were inconsistent among years compared with cattle grazing brome. Reductions in slaughter breakeven costs by grazing fall forages were observed in years with adequate moisture for forage growth. Forages that maximized grazing gain had the greatest effect on reducing slaughter breakeven cost.

]]> D. H. Shain et al. http://digitalcommons.unl.edu/animalscifacpub/776 http://digitalcommons.unl.edu/animalscifacpub/776 Fri, 01 Jun 2012 08:27:42 PDT The effects of stable flies on growing calves were examined using fly cages attached to the animals. Dry matter intake, DM digestibility (DMD), and behavioral responses of calves were monitored. Nine Holstein calves were exposed to 3 levels of stable flies (0, 10, 100 flies/animal) 3 times daily for 30 min. The study consisted of a 4-period crossover design; each period included 5-d adaptation, 7-d exposure, and 5-d postexposure. Calves were weighed at the beginning and end of each period. Feed consumption was continuously recorded. Fecal samples taken during and after exposure were used to determine DMD. Three calves were monitored for activity and defensive behavior during exposure. Caged stable flies successfully fed on the calves and invoked defensive behaviors similar to those observed in field studies. Defensive behaviors were proportionate to exposure level, and calves became more proficient at interfering with fly feeding over time. Stable fly exposure increased DMI relative to calf weight and decreased ADG/DMI. Calves initially exposed to 100 flies exhibited more defensive behaviors and lower relative DMI and ADG across all exposure levels relative to calves initially exposed to 10 flies. Stable fly exposure did not affect DMD, number of meals, time eating, or amount eaten per meal. Host defensive behavior, not reduced DMI or DMD, appears to be reducing ADG of calves exposed to stable flies. Results indicate that cages placed on calves may be used to study the effects of stable flies, but host exposure history and behavioral variables must be considered.

]]> L. A. Schole et al. http://digitalcommons.unl.edu/animalscifacpub/775 http://digitalcommons.unl.edu/animalscifacpub/775 Fri, 01 Jun 2012 08:25:00 PDT Based on applications of the 1996 National Research Council (NRC) Nutrient Requirement of Beef Cattle (2000 update) model at our laboratories and on use of the model to evaluate published literature, it is our assessment that the NRC model (Level 1) represents an advancement in nutrient requirements of grazing cattle. We evaluated 8 published studies (35 treatment observations) to compare observed changes in body condition score (BCS) to those predicted by the NRC model, and to develop criteria to help with application of the model to range cattle nutrition. When in vitro organic matter disappearance (IVOMD) of grazed diets was converted to DE [DE = (1.07 × IVOMD) − 8.13] and used as a proxy for TDN, there were no differences in observed vs. predicted BCS change (P = 0.44). A critical component of the 1996 NRC model is the incorporation of the metabolizable protein system. An accurate estimate of microbial efficiency is key to application of the metabolizable protein system. We propose the use of an equation to adjust microbial efficiency for diets less that 65% TDN. The NRC model should be applied to 30-d time intervals if animal requirements or forage quality are changing rapidly. Accurate inputs for stage of gestation, days into lactation, breed, milk production, dietary TDN, and microbial efficiency are necessary for the model to yield accurate results. Work is needed to define and model microbial efficiency, nitrogen recycling, and the quality of diets selected by grazing livestock in various environments.

]]> H. H. Patterson et al. http://digitalcommons.unl.edu/animalscifacpub/774 http://digitalcommons.unl.edu/animalscifacpub/774 Fri, 01 Jun 2012 08:22:12 PDT Four feeding regimens were evaluated in two different outside facilities [tree windbreak provided (SP) vs no wind protection provided (NP)] over two winter seasons. Feeding regimens were 1) 7.5% (DM basis) alfalfa hay (AH) diet (Low- Low); 2) 15% (DM basis) AH diet switched to a 7.5% (DM basis) AH diet under cold stress conditions (High-Low); 3) 7.5% (DM basis) AH diet switched to a 15% (DM basis) AH diet under cold stress conditions (Low-High); and 4) 15% (DM basis) AH diet (High-High). For feeding regimens High-Low and Low- High, cold stress was determined by use of a model, based on weather conditions and previous DMI, to predict lower critical temperature. Cattle fed in facilities with SP tended to perform better under a Low-Low feeding regimen; cattle fed in facilities with NP tended to benefit from the extra energy provided by switching to a lower fiber diet (High-Low feeding regimen) during cold stress. Across both facilities, the 5-d moving averages of wind chill index (WCI) and WCI >800 units had the best correlation with change in DMI. All diets except the High-High diet displayed significant linear relationships with increases in DMI and climatic variables in the NP facility, whereas cattle fed only the High- High diet displayed significant relationships in the SP facility. Heat production associated with the added fiber does not appear to be greater than that from added grain. Switching feedlot cattle, under cold stress, to higher fiber diets was not beneficial.

]]> T. L. Mader et al. http://digitalcommons.unl.edu/animalscifacpub/773 http://digitalcommons.unl.edu/animalscifacpub/773 Fri, 01 Jun 2012 08:19:41 PDT Three hundred twenty crossbred steer calves (308 kg) were used to determine the effects of corn processing and addition of urea on performance with diets containing wet corn gluten feed (WCGF). The treatment design was a 5 × 2 factorial with factors of corn processing (dryrolled, DRC; fine-ground, FGC; rolled high-moisture, RHMC; ground high-moisture, GHMC; or steam-flaked corn, SFC) and CP concentration (14 or 15%) with 4 pens per treatment and 8 steers per pen. The final diet contained 60% corn, 25% WCGF, 10% corn silage, and 5% supplement (DM basis). No significant protein × grain processing interactions occurred for feedlot performance or carcass variables. Steers fed DRC and FGC had similar DMI, but greater (P < 0.01) DMI, than those fed RHMC, GHMC, or SFC. Intakes were similar among cattle fed RHMC, GHMC, and SFC. Daily gain was similar among all treatments. Gain/ feed was significantly different among the processing treatments, except between RHMC and GHMC. Gain:feed was increased (P < 0.01) 3.8, 7.0, 8.7, or 11.8% for steers fed FGC, RHMC, GHMC, or SFC, respectively, compared with steers fed DRC. Calculated NEg was increased (P < 0.01) 5.1, 10.3, 10.9, and 15.4% for FGC, RHMC, GHMC, and SFC, respectively, compared with DRC. Protein concentration had no effect on performance, suggesting protein requirements were met at the lesser concentration of protein. Based on these results, when feedlot diets contain 25% WCGF, more intense processing of corn (i.e., high-moisture corn or SFC) improves feed efficiency compared with less intense methods.

]]> C. N. Macken et al. http://digitalcommons.unl.edu/animalscifacpub/772 http://digitalcommons.unl.edu/animalscifacpub/772 Fri, 01 Jun 2012 08:17:11 PDT Three corn processing methods were compared for use in 5,000- and 20,000-head capacity feedlots. Processing methods were dry-rolled (DRC), early harvest and ensiling high-moisture (HMC), and steam-flaked corn (SFC). Processing costs were determined to be $1.58, $4.71, and $9.57/t (metric ton; DM basis) for DRC, HMC, and SFC, respectively, for the 5,000-capacity feedlot. Processing costs were less for the 20,000-capacity feedlot at $0.81, $3.07, and $6.23/t (DM basis) for DRC, HMC, and SFC, respectively. Using these economic calculations in an 85% corn diet (DM basis), an improvement of dietary feed efficiency would need to be 2.4 and 6.1% for feeding HMC or SFC, respectively, compared with feeding DRC in a 5,000-capacity feedlot to be of economical value. For the 20,000-capacity feedlot, an improvement of dietary feed efficiency would need to be 1.7 and 4.2% for feeding HMC or SFC, respectively, compared with feeding DRC. Variables such as corn price, feed efficiency response, energy cost, and feedlot size determine eco- 1A contribution of the University of Nebraska Agricultural Research Division, Lincoln 68583. Journal Series No. 14358. This research was supported in part by funds provided through the Hatch Act. 2Present address: 2603 Riverview Drive, Grand Island, NE 68801. 3To whom correspondence should be addressed: gerickson4@unl.edu nomic returns for corn processing. Feeding SFC appears to generate economic return in both sizes of feedlots compared with feeding HMC or DRC. Calculated economic returns involving HMC were more variable than the economic returns generated from DRC data.

]]> C. N. Macken et al. http://digitalcommons.unl.edu/animalscifacpub/771 http://digitalcommons.unl.edu/animalscifacpub/771 Fri, 01 Jun 2012 08:15:45 PDT Three finishing experiments were conducted in commercial feedlots to determine effects of implant programs on finishing heifer performance, carcass characteristics, and economics. A total of 3,307 heifers were used in the three experiments. Overall, four treatment comparisons were tested within the three separate experiments. Treatment groups included the following: 1) heifers implanted with Synovex® Plus (Fort Dodge Animal Health; Fort Dodge, IA) but not fed melengestrol acetate (MGA®; Pharmacia and Upjohn Company; Kalamazoo, MI) , 2) heifers implanted with Synovex® Plus and fed MGA®, 3) heifer implanted with Revalor®-H (Intervet Inc.; Millsboro, DE) and fed MGA®, and 4) heifers implanted with Finaplix®-H (Intervet Inc.) and fed MGA®. Common treatments of Synovex® Plus and dietary MGA® as well as Finaplix®-H and dietary MGA® were used in each of the three experiments. Finishing heifers fed MGA® and implanted with Synovex® Plus had 3.9 and 4.1% greater (P<0.10) ADG than did heifers implanted with Revalor®-H or Finaplix®-H and fed MGA®, respectively. Daily gain did not differ for heifers implanted with Revalor®-H or Finaplix®- H. Feeding MGA® to heifers implanted with Synovex® Plus increased ADG and decreased deleterious effects on quality grade; however; carcasses had greater fat thickness. Fewer carcasses of heifers fed MGA® and implanted with Synovex® Plus or Revalor®-H were graded Choice in comparison with the carcasses of those implanted with Finaplix®-H. When selling heifers on a carcass-merit basis, net returns did not differ among heifers implanted with Synovex® Plus, Revalor®- H, or Finaplix®-H when fed MGA®. When selling heifers on a dressed basis, net return was maximized (P<0.10) with the use of Synovex® Plus and supplementation with MGA® compared with Synovex® Plus and no MGA® supplementation, Revalor®-H and MGA® supplementation, and Finaplix®-H and MGA® supplementation.

]]> C. N. Macken et al. http://digitalcommons.unl.edu/animalscifacpub/770 http://digitalcommons.unl.edu/animalscifacpub/770 Fri, 01 Jun 2012 08:11:29 PDT Five trials (19 treatments) conducted at the University of Nebraska-Lincoln (UNL) on lactating dairy cattle were analyzed to determine how the concentration of ADIN in the ration affects total tract N digestibility. Additionally, 6 published studies (13 treatments) were included to expand the data set. Results from the UNL trials showed that as the concentration of ADIN in the ration increased, the digestibility of ADIN also increased. However, the relationship was poor (r² = 0.29). To account for random effects among trials, a meta-analysis was conducted. In the UNL trials, as the ration concentration of ADIN increased, total tract N digestibility decreased; this relationship was moderate (r² = 0.55). A meta-analysis of the published studies illustrated similar results with a moderate correlation (r² = 0.44). All data were combined for a meta-analysis, and similar results illustrated a moderate relationship (r² = 0.58). There was positive relationship between ADF and the concentration of ADIN in the UNL trials; however, the relationship was poor (r² = 0.19). Additionally, a poor, negative relationship (r² = 0.14) was observed between ADF and N digestibility in the UNL trials. Milk yield (31.9 ± 3.1 kg/d) in the UNL trials was unaffected (r² = 0.01) by the concentration of ADIN in the ration. These data suggest ADIN is partially digestible, N digestibility is moderately influenced by ADIN concentration in rations, there is a poor relationship between ADF and the concentration of ADIN, and milk yield is unaffected by the concentration of ADIN.

]]> K. J. Machacek et al. http://digitalcommons.unl.edu/animalscifacpub/769 http://digitalcommons.unl.edu/animalscifacpub/769 Fri, 01 Jun 2012 08:09:05 PDT One hundred sixty English-cross steers (244 kg, SD=23 kg) were used in each yr of a 2-yr study to determine effects of sorting on performance, carcass characteristics, variability, and profitability in a long yearling system utilizing ranch-source calves. Steers were back grounded during winter then grazed smooth brome-grass pastures followed by warm season native range prior to entering the feedlot in the fall. Steers were stratified by BW and allotted to 1 of 4 treatments: 1) 40 head sorted by pre-grazing BW where heavy steers entered the feedlot in July (PST), 2) 40 head sorted by BW entering the feedlot (FDL), 3) 60 head sorted by BW and fat thickness at the end of the feeding period (IND), and 4) 20 head that were not sorted (UNS). No differences were observed for performance during back-grounding or grazing phases (P > 0.30). Cattle receiving PST sorting weighed less entering the feedlot and consumed less feed with less feedlot ADG compared to other treatments (P < 0.05). No differences in feed efficiencies were detected (P = 0.84). Cattle receiving PST sorting had greater marbling scores (P < 0.05) and less variation in BW upon feedlot entry which resulted in less variation in carcass weight compared with UNS (P < 0.05). Cattle sorted by BW entering the feedlot tended (P = 0.08) to have less variation in carcass weight compared with UNS. There were no differences in carcass weight or profitability when calculated on either a live or value basis. No sorting strategy increased carcass weight, reduced discounts for overweight or corpulent carcasses, or improved profitability over UNS.

]]> J. C. Macdonald et al. http://digitalcommons.unl.edu/animalscifacpub/768 http://digitalcommons.unl.edu/animalscifacpub/768 Fri, 01 Jun 2012 08:05:12 PDT When feedlot pens are scraped in the spring and summer, manure is often stored before land application can occur in the fall. Manure stockpiled or composted was evaluated for nutrient losses in 2 experiments for 104 (Exp. 1) and 111 d (Exp. 2). Stockpiles (n = 2 in Exp. 1 and n = 3 in Exp. 2) and compost windrows (n = 6 in Exp. 1 and n = 4 in Exp. 2) were constructed with feedlot manure scraped from pens and sampled upon construction and throughout the storage period. In Exp. 1, N loss was 3 times greater (P < 0.01) for compost compared with stockpile on d 104 (43.6 and 14.3%, respectively). Loss of C was 34.7% greater (P < 0.01) for compost compared with stockpile on d 104 (54.4 and 40.4%, respectively). Total mass loss (water + DM) was not different (P = 0.30) among storage methods on d 104 (20.0 and 15.8% for compost and stockpile, respectively). In Exp. 2, N loss from compost was 42.1% greater (P < 0.01) compared with stockpiling on d 111. Carbon losses in Exp. 2 were not different (P = 0.77) among storage methods on d 111 (38.4 and 37.5% for compost and stockpile, respectively). Total mass loss in Exp. 2 was less compared with Exp. 1 and was not different (P = 0.23) among storage methods (5.7 and 3.6% for compost and stockpile, respectively). When evaluated on a nutrient basis, stockpiled manure had greater N and C concentrations compared with composted manure.

]]> M. K. Luebbe et al. http://digitalcommons.unl.edu/animalscifacpub/767 http://digitalcommons.unl.edu/animalscifacpub/767 Fri, 01 Jun 2012 08:03:03 PDT Two experiments were conducted to determine the effects of corn hybrid and processing method on the site and extent of nutrient digestibility and ruminal fermentation. Treatments consisted of 2 processing methods, dry-rolled corn (DRC) and high-moisture corn (HMC), and 3 hybrids, H-8562 (1), 33P67 (2), and H-9230 (3), in a 2 × 3 factorial arrangement. In Exp. 1, six ruminally cannulated crossbred steers (436 ± 8 kg) were used in a 6 × 6 Latin square design. Total tract DM, OM, and starch digestibility (STD) were greater (P < 0.10) for HMC compared with DRC. A hybrid × processing method interaction (P < 0.10) was observed for propionate concentration and the acetate-to-propionate ratio. In Exp. 2, two ruminally and duodenally fistulated steers were used to determine the site and extent of nutrient digestion using the mobile bag technique at 2 ruminal incubation times. Ruminal STD was not different (P = 0.14) among hybrids but was greater (P < 0.01) for HMC compared with DRC. Postruminal and total tract STD were greater (P < 0.01) for hybrids 1 and 3 than for hybrid 2, and were greater (P < 0.01) for HMC than DRC. In both experiments the geometric mean diameter and geometric SD were influenced (P < 0.05) by both hybrid and processing method. More intense processing methods or selection of hybrids with softer kernels will result in greater digestibility and ruminal propionate concentrations. Digestibility of corn samples can be characterized using the mobile bag technique but particle size can influence results.

]]> M. K. Luebbe et al. http://digitalcommons.unl.edu/animalscifacpub/766 http://digitalcommons.unl.edu/animalscifacpub/766 Fri, 01 Jun 2012 07:57:47 PDT The ability of grazing animals to enhance quality of diet by selection is important in production. The study determined the effects of selection on dietary quality of cattle grazing monocultures of smooth bromegrass (Bromus inermis Leyss; SB), switchgrass (Panicum virgatum L.; SG), and big bluestem (Andropogon gerardii Vitman; BB) as influenced by plant maturity. Three ruminally-fistulated steers (295 kg) strip-grazed SB, SG, and BB at vegetative, elongation, early reproductive, and a regrowth stage of development. Selection was maximized by providing cattle access to 40 kg of DM/d per head. Clipped samples were compared with dietary samples accumulated during 45 min grazing following total rumen evacuation. Dietary CP was enhanced 3 to 4% for SG and BB, and 8% for SB (P < 0.05). Dietary IVDMD was enhanced at elongation and reproductive stages for SG and BB and vegetative and reproductive stages for SB. Dietary NDF was 7 to 13% less (P < 0.05).- in SG compared with forage-on-offer, whereas there was no effect with SB and BB diets. Diets of cattle grazing SG and BB had less ADF than clipped forage at elongation and reproductive stages, whereas ADF for the SB diet was less at the elongation phase (P < 0.05). Dietary lignin did not exceed 4% whereas the grass-on-offer was much greater. Regrowth produced forage and diets comparable to the elongation stage. If adequate forage is available, the selection ability of cattle can provide a superior diet compared with forage-on-offer. When the quality of warm-season grasses has declined, animal selection allows for potentially greater animal gain when grass quality is not optimum.

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