Search

The objective of this study was to determine the impact of a bout of ruminal acidosis on gas emissions of cattle unadapted to a high concentrate diet. Eleven ruminally cannulated steers (body weight = 352 kg ± 27) were blocked into 3 groups based on initial body weight. Prior to the start of the experiment, animals were consuming a forage-based diet as well as adapted to the headbox style respiration chambers. Additionally, prior to the experiment, gas emission data were collected over a 24-hour period when cattle received an ad libitum forage-based diet for use as a covariate in the statistical analysis. For the experiment, steers were moved into headboxes at the conclusion of a 24 hour fast and subsequently received 1 of 2 treatment diets: control (CON), forage-based diet or acidosis (ACID), concentrate-based diet. Steers remained in the headboxes for 48 hours. Gas concentrations from each headbox were collected hourly and analyzed with an infrared photoacoustic gas analyzer. Data were analyzed with the MIXED procedure of SAS 9.4. There was a tendency for a treatment × day effect (P = 0.09) with steers on the ACID treatment consuming 1.95 kg less on day 2 than CON steers. Dry matter intake was affected by day (P < 0.01) with steers consuming 4.35 kg less on day 2. There was an effect of treatment (P < 0.01) with CON steers having a greater ruminal pH than ACID steers. Steers on the ACID treatment had less CO2 emissions (P < 0.01) than CON steers, but there were no observed differences (P ≥ 0.19) in O2 emissions or respiratory quotient. Acidosis decreased dry matter intake and CO2 emissions but not O2 emissions for cattle unadapted to a high concentrate diet.

Three experiments evaluated the effects of ractopamine hydrochloride (RAC) dose and duration on growth performance and carcass characteristics of feedlot steers. In total, 1,509 crossbred steers (530 kg initial BW [SD 22]) were used in a randomized complete block design using a 3 × 3 factorial treatment structure. Treatments consisted of RAC dose (0, 100, or 200 mg/steer daily) and duration (28, 35, or 42 d) of RAC feeding prior to harvest. Initiation of RAC dose was staggered (7 d apart) based on RAC duration, which resulted in common days on feed among treatments. Data from the 3 experiments were combined for statistical analyses. There were no RAC dose × duration interactions ( ≥ 0.85) for growth performance. Live final BW was not different ( ≥ 0.24) as RAC dose increased. Dry matter intake linearly decreased ( < 0.01) as RAC dose increased. Live ADG and G:F linearly increased ( ≤ 0.01) as RAC dose increased. Carcass-adjusted ADG and G:F linearly increased ( ≤ 0.02) as RAC dose increased. Compared with steers fed 0 mg RAC/steer daily, G:F was improved by 5.0 and 13.0% when steers were fed 100 ( = 0.31) and 200 ( = 0.01) mg RAC/steer daily, respectively. Hot carcass weight tended ( = 0.10) to linearly increase as RAC dose increased, with carcasses from steers fed 100 ( = 0.38) and 200 ( = 0.10) mg RAC/steer daily being 2.2 and 4.1 kg heavier, respectively, than carcasses from steers fed 0 mg RAC/steer daily. Increasing RAC dose linearly ( < 0.01) increased LM area and linearly ( = 0.02) decreased marbling score. Live final BW was not different ( ≥ 0.60) among RAC durations. Carcass-adjusted final BW, ADG, and G:F were not different ( ≥ 0.41) as RAC duration increased. Carcass traits did not differ ( ≥ 0.18) among RAC duration. Feeding 200 mg RAC/steer daily improved ADG, feed efficiency, and HCW. Increasing the feeding duration of RAC had no effect of growth performance or carcass characteristics. These data indicate that feeding 200 mg RAC/steer daily for 28 d improves steer growth performance.

Maize production in the U.S. was about 316 million metric tons in 2010. That amount is expected to increase in the future due to greater yields/hectare and more hectares planted. From 1950 until 2006 the supply of maize grain was much greater than demand. Government programs supplemented farmers, enabling them to produce abundant amounts of maize grain at low prices. The low prices of maize grain encouraged feeding large amounts to livestock and poultry. As late as 2000, 60% of maize grain produced was fed to livestock and poultry. The development of the fuel ethanol industry has changed both the price of maize grain and the usage by livestock and poultry. In 2010 only 42.9% of U.S. maize grain was fed to livestock and poultry while 41.8% was used for fuel ethanol production, and 11.2% for food. There are two byproducts from fuel ethanol production that replace some of the maize grain, especially in cattle production—distillers grains and maize gluten feed. Both of these byproducts are very well utilized by cattle. Depending upon plant production logistics, distillers grains has 110–140% the feeding value of the maize grain replaced and maize gluten feed has 100–110% the feeding value of maize grain. Values are less for lactating dairy cows but both byproducts serve as excellent protein sources. Byproducts replace 35–45% of the maize grain used to produce fuel ethanol. Essentially all of the cattle in the U.S. are “finished” on diets containing 80–85% concentrates. In the past the concentrates were comprised primarily of maize grain but now are a mixture of maize and byproducts. In the US the forage part of the corn plant is utilized in three ways. Some is harvested as whole plant maize silage. The silage is used as both an energy source and a roughage source in feedlot diets. Maize silage is also used to “background” cattle. This term is used to describe a growing phase based on forages prior to cattle being placed on “finishing” diets. The second use of maize forage (referred to as residue) is residue harvest after grain harvest and fed as a roughage source in finishing diets or mixed with wet byproducts and fed as an energy source to “background” cattle or beef cows. The other use of the maize “residue” is through grazing after grain harvest. Beef cows or backgrounding calves are placed on the maize fields after grain harvest where they select the higher quality forage components and any residual grain left in the field after harvest. Residual grain in residue is of high quality and selected first by the cattle. The husk is palatable and highly digested while the leaf is palatable but not as digestible. Quality of the diet declines with time of grazing because the higher quality parts are selected first. Generally, about 15% of the residue is consumed leaving 85% for erosion control and soil organic matter. Under this system beef cows need little supplementation while growing calves need supplementation of both protein and energy to yield economical growth.

Transcriptome dynamics in the longissimus muscle (LM) of young Angus cattle were evaluated at 0, 60, 120, and 220 days from early-weaning. Bioinformatic analysis was performed using the dynamic impact approach (DIA) by means of Kyoto Encyclopedia of Genes and Genomes (KEGG) and Database for Annotation, Visualization and Integrated Discovery (DAVID) databases. Between 0 to 120 days (growing phase) most of the highly-impacted pathways (eg, ascorbate and aldarate metabolism, drug metabolism, cytochrome P450 and Retinol metabolism) were inhibited. The phase between 120 to 220 days (finishing phase) was characterized by the most striking differences with 3,784 differentially expressed genes (DEGs). Analysis of those DEGs revealed that the most impacted KEGG canonical pathway was glycosylphosphatidylinositol (GPI)-anchor biosynthesis, which was inhibited. Furthermore, inhibition of calpastatin and activation of tyrosine aminotransferase ubiquitination at 220 days promotes proteasomal degradation, while the concurrent activation of ribosomal proteins promotes protein synthesis. Therefore, the balance of these processes likely results in a steady-state of protein turnover during the finishing phase. Results underscore the importance of transcriptome dynamics in LM during growth.

Studies were conducted to evaluate the effect of early weaning steer calves on BW gain, feedlot performance, and carcass characteristics in two herds located in the Northern Great Plains, USA. Steer calves from predominantly Angus×Hereford dams were stratified within dam age and calving date (Fort Keogh Livestock and Range Research Laboratory (LARRL), Miles City, MT, USA; n =354) and randomly assigned to one of three weaning treatments. In addition, steer calves from Angus and Angus×Simmental dams ( n =200; Judith Gap (JG), MT, USA) were stratified within breed group by age, calving date, and AI sire. Steer calves either remained with their dams until normal weaning (NW) at approximately 213-d of age or were early weaned at approximately 80-d of age onto one of two early weaning (EW) diets. Steer calves assigned to EW treatments received one of the following diets: (1) 17.5% CP (69% RDP and 7.53 MJ/kg NEm); or (2) 17.5% CP (57% RDP and 7.69 MJ/kg NEm). At time of normal weaning all LARRL steers were gathered and brought into pens at LARRL and held for 22 (2005) or 28-d (2006) before being sold to a commercial feedlot. Sire-identified steers from JG were sent to the University of Illinois for a finishing trial following a 28-d holding period. Steers that were EW were heavier ( P P P =0.79) regardless of weaning treatment whereas sire-identified JG steers that received EW treatment were harvested at a younger age ( P P =0.05; upper 2/3 choice or better) than NW treated steers ( P

Harvest date greatly affects the biomass yield, moisture, and quality of corn and stover. Traditionally, corn and stover have been harvested at lower moisture levels. However, corn stover and grain can be more effectively utilized as animal feed and biomass-ethanol feedstock if they are collected before in-field dry down. This study determined dry matter yield, moisture content, and quality of corn and stover before, during, and after grain maturity in central Illinois. The two-year average kernel moisture was 37.4% (w.b.) when reaching physiological maturity. At the same time, the average stover moisture was 67.7% (w.b.). The dry matter yield of grain increased rapidly until reaching grain maturity and remained relatively stable after grain maturity, with an average yield of 11.2 t ha-1 over the two-year study. For corn stover, the two-year average dry matter yield was 14.7 t ha-1 at the beginning of the study (filling stage), and it decreased to 13.2 t ha-1 at grain physiological maturity and further decreased to 11.0 t ha-1 throughout grain dry down. During grain dry down, the moldy kernel percentage increased from 2.1% to 4.1% and the stalk lodging percentage increased from 1.2% to 3.6%. The results of this study showed that early harvest of corn and stover at grain maturity has several advantages: higher dry matter yield of stover, lower moldy kernel percentage, and fewer plant lodgings.

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) 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.

Angus × Simmental heifers (n = 192; BW = 253 ± 2 kg) were utilized to evaluate the effects of source of energy on performance, ultrasonic, carcass, and economic characteristics of early-weaned heifers. Treatments investigated were 1) high starch (HS); 2) intermediate starch (IS); 3) low starch (LS); and 4) pasture (PAST). The experimental growing period was 73 d. The finishing period was 103 d for the HS, IS, and LS heifers and 131 d for the PAST heifers (fed the IS diet). Gain and intake during the growing, finishing, and overall period increased linearly (P < 0.01) as the level of starch decreased. During the finishing period, PAST heifers gained faster (P < 0.01), ate more feed (P < 0.01), and were more efficient (P = 0.04) than IS heifers. The IS heifers had more back fat, larger ribeye areas, and greater marbling scores (P < 0.01) than PAST heifers after the growing period. The IS heifers also deposited more (P < 0.01) marbling per day than PAST heifers during the growing, finishing, and overall period at the end of the trial. The IS heifers had greater (P < 0.01) marbling scores than PAST heifers. Total cost, carcass value, and profit increased linearly (P < 0.01) as starch level decreased. The IS heifers had greater (P < 0.01) carcass values and were more (P < 0.01) profitable than PAST heifers. This study implies that when utilizing long-fed (322 d) heifers in an accelerated finishing program, by-products can be effectively fed during the final (103 to 131 d) finishing period with no reduction in QG. Placing heifers on pasture reduced the ability of the heifers to marble in the feedlot despite faster gain.

The number and nutrient composition of corn-based coproducts will expand as ethanol producers seek to optimize the efficiency of ethanol production and the value of the coproducts they produce. For example, modified wet distillers grains plus solubles are produced by adding the condensed solubles to partially dried distillers grains so that the resulting product contains approximately 50% DM. Other innovative technologies have been developed to fractionate corn or distillers dried grains with solubles (DDGS), or both, for recovering additional coproducts and improving nutritional composition of DDGS. Two (i.e., wet and dry) corn-fractionation technologies have been developed to remove the germ, pericarp fiber, or endosperm fiber before fermentation, resulting in a significant reduction in the amount of DDGS produced and a corresponding increase in its protein content. Other fractionation technologies include removal of oil by centrifugation after fermentation but before DDGS production or removal of oil by solvent extraction from DDGS. Technology to recover pericarp fiber by sieving and aspiration after DDGS production has also been developed. Germ, pericarp fiber, endosperm fiber, or oil can be used as feedstocks for producing other marketable coproducts or can be used as ingredients in animal diets. One example of a new corn coproduct available to the beef industry is bran cake. This product results from combining corn bran (i.e., pericarp fiber) and distillers solubles produced from a corn dry fractionation process. When bran cake replaced a mixture of high-moisture and dry-rolled corn at up to 45% of a finishing diet, BW gains and feed efficiency were improved. In high-forage diets, the corn bran had approximately 85% the energy value of distillers grains. How rapidly these technologies are adopted will be driven by the economic advantages achieved over the traditional dry and wet milling processes.

The rapid expansion of ethanol production has resulted in an abundance of co-products available to cattle feeders. Two hundred forty steers were used to determine the optimum length of time for feeding a diet containing 40% dried distillers grains with solubles (DDGS) and 35% soybean hull (SH, DM basis) to feedlot cattle. Treatments consisted of feeding the DDGS-SH diet for 56, 84, 112, 140, and 196 d before switching to a corn-based finishing diet. All cattle were harvested after 196 d and serial ultrasound measurements were taken every 28 d. Data were analyzed for linear and quadratic effects, and orthogonal polynomial contrasts of 56 vs. 196 and 84 vs. 112 to 140 d were analyzed. Adjusted final BW and ADG increased linearly (P

Two hundred heifers (287.8 + 34.5 kg) were randomly assigned to 4 dietary treatments containing either 0, 15, 30, or 45% wet brewers grains (WBG) on a DM basis. The control diet consisted of 15% corn silage, 75% whole high-moisture corn, and 10% soybean meal-based supplement on a DM basis. Two full weights were averaged at the initiation of the trial and carcass-adjusted BW was used to determine the final BW. Heifers were pen-fed (5 pens per treatment, 10 head per pen) for 160 d. Adjusted final BW, and G:F were not significantly different among dietary treatments. Dry matter intake, ADG, and final BW were quadratic (P

Research has demonstrated that triiodothyronine and thyroxin are correlated with marbling (MARB) deposition in Wagyu cattle. Polymorphisms in the 5' region of the thyroglobulin gene have been associated with an improvement in overall fattening and could be used as a gene marker for MARB. The commercially available GeneSTAR MARB test measures the specific thyroglobulin gene polymorphism and identifies cattle as having 0, 1, or 2 copies of the allele; these are identified as 0-STAR, 1-STAR, or 2-STAR, respectfully. Early weaned Simmental steers (n = 192) of known genetics were individually fed over a repeated 4-yr trial period to determine the correlations between GeneSTAR MARB test [Genetic Solutions/Bovigen Pty. Ltd. (Australia) in conjunction with Frontier Beef Systems, LLC (Louisville, CO)] results and intramuscular fat (IMF) deposition. Yearling weight, MARB, percent retail cuts, and carcass weight EPD were calculated for each steer. Steers were weaned at 88.0 +/- 1.1 d, pen-fed a high-concentrate diet for 84.5 +/- 0.4 d before allotment, and subsequently individually fed a 90% concentrate diet composed primarily of cracked corn and corn silage for 249.7 +/- 0.7 d. Steers were slaughtered at 423.3 +/- 1.4 d. Deoxyribonucleic acid samples were used by Genetic Solutions/Bovigen (Australia) for GeneSTAR MARB analysis. Steers with allele types of 0-STAR (n = 47), 1-STAR (n = 95), and 2-STAR (n = 33) had no effect (P > 0.10) on MARB score, chemically determined IMF percentage, quality grade, or percent low Choice and better. There were no differences (P > 0.10) in performance or other carcass parameters among the allele types. GeneSTAR results were not associated with MARB (P > 0.10). Conversely, MARB EPD was correlated (P < 0.01) with MARB score (r = 0.44) and IMF percentage (r = 0.27). Thus, in this management system, MARB EPD is an accurate predictor of IMF deposition. These data suggest that the GeneSTAR MARB marker was not an efficacious predictor of IMF deposition in early weaned Simmental steers fed a high-energy diet.

In a 4-yr study, early-weaned Simmental steers (n = 192) of known genetics were individually fed to determine EPD, performance, and carcass measurements explaining variation in carcass value and profitability across incremental days on feed (DOF) when sorted by HCW, calculated yield grade (YG), or at their highest profit endpoint (BEST). Steers were weaned at 88.0 +/- 1.1 d of age, pen-fed a high-concentrate diet for 84.5 +/- 0.4 d, individually fed for 249.7 +/- 0.7 d, and slaughtered at 423.3 +/- 1.4 d of age. Carcass weight, YG, and marbling score (MS) were predicted using real-time ultrasound throughout the finishing period to calculate carcass value and profitability at 90, 60, 30 d preslaughter and under three individual sorting strategies. Sorting strategies included marketing the 25 and 50% heaviest HCW, the highest YG at d 60 and 30, or the remaining 25% at 0-d endpoints. Independent variables were year, weaning weight EPD, yearling weight EPD, marbling EPD, DMI, ADG, HCW, YG, and MS. Profit was quadratic in response to increased DOF; the greatest economic return was noted on d 30 (pre-slaughter). Final weight, DMI, HCW, MS, and YG increased (linear; P < 0.001) with additional DOF, and ADG and G:F decreased (linear; P < 0.001). Total cost of gain was quadratic (P < 0.001), and incremental cost of gain rose at an increasing rate (quadratic; P < 0.001) with increased DOF. With increasing DOF, HCW importance decreased from 58 to 21%; MS was variable, ranging from 18 to 23%; and YG and DMI were minor contributors to profit variation. Among sorting strategies, final BW and HCW were greater for BEST, whereas other measurements were similar. Sorting individuals by HCW, YG, or at BEST increased profitability 3.70 dollars, 2.52 dollars, or 30.65 dollars over the optimal group DOF endpoint (d 30). Retrospective analyses illustrated that sorting does not need to pinpoint each animal's profit optimum to result in economic gains; rather, increasing HCW and decreasing weight- and YG-related penalties improved profitability. Opportunities may exist with existing and new technology to uniformly allocate cattle into feeding and marketing groups, decrease overfeeding, and increase carcass value and profitability.

One grazing and two feeding experiments were conducted to compare the feeding value of corn residue or corn grain from a genetically enhanced corn hybrid (corn rootworm-protected; event MON 863) with nontransgenic, commercially available, reference hybrids. In Exp. 1, two 13.7-ha fields, containing corn residues from either a genetically enhanced corn root-worm-protected hybrid (MON 863), or a near-isogenic, nontransgenic control hybrid (CON) were divided into four equal-sized paddocks. Sixty-four steer calves (262 +/- 15 kg) were stratified by BW and assigned randomly to paddock to achieve a stocking rate of 0.43 ha/steer for 60 d, with eight steers per paddock and 32 steers per hybrid. A protein supplement was fed at 0.45 kg/steer daily (DM basis) to ensure protein intake did not limit performance. Steer ADG did not differ (P = 0.30) between steers grazing the MON 863 (0.39 kg/d) and CON (0.34 kg/d) corn residues for 60 d. The four treatments for the feeding experiments (Exp. 2 and 3) included two separate reference hybrids, the near-isogenic control hybrid (CON), and the genetically enhanced hybrid (MON 863) resulting in two preplanned comparisons of CON vs. MON 863, and MON 863 vs. the average of the reference hybrids (REF). In Exp. 2, 200 crossbred yearling steers (365 +/- 19 kg) were fed in 20 pens, with five pens per corn hybrid. In Exp. 3, 196 crossbred yearling steers (457 +/- 33 kg) were fed in 28 pens, with seven pens per corn hybrid. In Exp. 2, DMI and G:F did not differ (P > 0.10) between MON 863 and CON; however, steers fed MON 863 had a greater (P = 0.04) ADG than steers fed CON. Gain efficiency was greater (P = 0.05) for MON 863 cattle than for REF cattle in Exp. 2, but other performance measurements (DMI and ADG) did not differ (P > 0.10) between MON 863 and REF. No differences (P > 0.10) were observed for performance (DMI, ADG, and G:F) between MON 863 and CON or MON 863 and REF in Exp. 3. In terms of carcass characteristics, no differences (P > 0.10) were observed between MON 863 and CON, as well as MON 863 and REF, for marbling score, LM area, or 12th rib fat thickness in both Exp. 2 and 3. Overall, performance was not negatively affected in the corn residue grazing or feedlot experiments, suggesting the corn rootworm-protected hybrid (event MON 863) is similar to conventional, nontransgenic corn grain and residues when utilized by beef cattle.

Early weaned Simmental steers (n = 192) were individually fed in a 4-yr study to determine expected progeny differences, performance, and carcass factors explaining variation in carcass value and profitability across various pricing scenarios. Steers were weaned at 88.0 ± 1.1 d of age, pen-fed a high-concentrate diet for 84.5 ± 0.4 d, individually fed for 249.7 ± 0.7 d, and harvested at 423.3 ± 1.4 d of age. Input cost and output prices were standardized using 5-yr averages. Variable dressed prices ($96, 108, 120, and 132/45.4 kg), Choice-Select spreads (Ch-Se; $4, $8, $12, $16, and $20/45.4 kg), and feed costs [corn = $58.93, $78.57, $98.21, $117.86, and $137.50/tonne; soybean meal (SBM) = $165, $220, $275, $330, and $385/tonne) were evaluated. Independent variables were weaning and yearling BW, marbling, expected progeny difference, DMI, ADG, feed efficiency, hot carcass weight (HCW), calculated yield grade (YG), and marbling score (MS). With rising dressed prices, HCW importance increased, and MS decreased, for value; HCW increased for profit. With an expanding Ch-Se, MS importance increased, and HCW decreased, for value; MS increased, and ADG, HCW, and YG diminished, for profitability. With escalating feed cost, HCW and MS importance tended to decrease for profitability, and YG and performance exhibited modest non-linear changes. Second-order interactions were also analyzed. Models represent relative importance of factors contributing to value and profitability in early weaned Simmental steers based on historical pricing scenarios. Factors would be expected to change with different cattle types, management, and future marketing conditions, but may be used as a benchmark for future research.

Three feedlot experiments examined the effects of vitamin A (VA) on marbling and serum retinol (ROL) in Angus × Simmental cattle. Diets contained 2300 [low VA (LVA)] or 7250 IU VA/ kg [high VA (HVA)]. In Exp. 1, 48 early weaned (51.0 ± 2.2 d) heifers (309.3 ± 7.0 kg; 12 pens) were fed ad libitum or were limit-fed 70 or 85% of ad libitum intake for 183 d then were fed for ad libitum intake for 149.3 ± 4.1 d. Vitamin A treatments were fed for 163.3 ± 4.1 d, and heifers were harvested at compositional endpoints. Serum was collected three times during the experiment. Limitfed heifers had improved (P

Seasonal variation in cattle grading Choice exists with percentages of carcasses grading higher in the spring and gradually declining throughout the summer with a low in October. Various nutritional or pharmacological agents have been shown to affect adipose conversion in vitro and in vivo. High (5 to 50 μM) levels of dietary fat-soluble vitamins, especially retinoic acid (RA) and 1,25-dihydroxyvitamin D 3 (D 3 ), inhibit adipocyte development, specifically bovine marbling, while lesser (≤10 nM) levels actively stimulate this deposition. This review was conducted to highlight the regulatory effects of vitamins A and D on adipocyte differentiation and offer a potential explanation for seasonal fluctuation in beef quality grades. Serum retinol concentration was negatively correlated with beef marbling index. Steers consuming diets containing low vitamin A concentration exhibited less serum retinol and produced greater marbling scores compared with steers consuming high vitamin A diets. Seasonal variation in quality grade may be explained by previous intake of vitamin A from lush forages and/or vitamin D synthesis from long day sun exposure. Cattle placed in the feedlots in spring or early summer are commonly grazed on lush forages, fed during the long day-length months and marketed in the fall, coinciding with seasonal lows for quality grade. Excessive circulating levels of vitamins A and D diminished adipocyte hyperplasia, lessened marbling score, and may partially explain seasonal depressions in carcasses grading Choice. Further research is necessary to elucidate the timing and dietary level of vitamins A and D during the finishing period and their relationship to high quality beef production.

Three experiments were conducted to compare the feeding value of genetically enhanced corn (Roundup Ready corn events GA21 and nk603) with nontransgenic hybrids. The four treatments included two separate reference hybrids (REF), the near-isogenic control hybrid (CON), and the genetically enhanced corn (RR), resulting in two preplanned comparisons of CON vs. RR and RR vs. the average of REF. In Exp. 1 (RR event GA21), 175 steers (BW = 427 kg) were fed in 25 pens with seven pens per corn hybrid, except CON, which contained four pens due to limited quantities of that hybrid. In Exp. 2 (RR event nk603), 196 steers (BW = 420 kg) were fed in 28 pens with seven pens per corn. In Exp. 3 (RR event nk603), 200 steers were fed in 20 pens, with a similar treatment design to Exp. 2 and five pens per corn. All experiments were conducted as completely randomized designs and utilized corn produced at University of Illinois (Exp. 1 and 2) and University of Nebraska (Exp. 3) research farms under identity-preserved protocols. In all experiments, DMI, ADG, and feed efficiency were similar (P > 0.30) between RR and REF. In Exp. 1 and Exp. 2, RR was not different (P > 0.25) than CON for growth performance. In Exp. 3, RR was not different from CON for ADG and DMI (P > 0.15) or for feed efficiency (P = 0.08). No differences were observed between RR and CON or RR and REF for carcass weight, longissimus dorsi area, and marbling scores in any of the experiments. Subtle differences were observed between RR and either CON or REF for fat depth in each experiment; however, cattle fed RR were not consistently greater and varied from either the CON or the REF (but not both contrasts) within an experiment. Based on these results, insertion of glyphosate-tolerant genes had no significant effect on nutritive quality of corn. Performance and carcass characteristics were not influenced, which suggests that Roundup Ready corn is similar to conventional, nontransgenic corn when fed to finishing feedlot cattle.

Three experiments were conducted to evaluate the effects of restricting the intake of 25% wheat middling diets during the growing phase on finishing phase performance and carcass composition of early weaned steers. In Exp. 1, early weaned Wagyu cross steers were used to compare effects of ad libitum (AL) intake vs restricted (RS; 75% AL) intake of a high concentrate diet. In Exp. 2, early weaned Continental cross steers were used to compare effects of AL intake vs RS intake of a high concentrate diet or hay for AL intake during the growing phase on finishing phase performance and carcass composition. In Exp. 3, early weaned Wagyu cross steers were used to evaluate the same treatments as Exp. 2. Steers were fed until they had ca. 1.0-cm subcutaneous fat cover. In Exp. 1, because steers fed for AL intake were leaner than RS-fed steers, backfat was used as a covariate for finishing phase performance and carcass composition. For Exp. 1, 2, and 3, steer performance for the finishing phase was adjusted to a common dressing percentage. In the growing phase of Exp. 1, steers fed AL gained 18.6% more (P

Financial, economic, and biological data from cow-calf producers participating in the Illinois and Iowa Standardized Performance Analysis programs were analyzed. Data were collected from 1996 to 1999; each herd-year represented one observation. The database consisted of 225 commercial herd observations (117 Iowa; 108 Illinois) and ranged from 20 to 373 cows. Analyses were conducted on financial and economic costs of production. Each observation was analyzed as the difference from the mean for that given year to eliminate environmental and cattle cycle effects. The dependent variable used as an indicator of profit was return to unpaid labor and management per cow (RLM). Independent variables were feed, operating, depreciation, capital, hired labor costs, calf weight, calf price, cull weight, cull price, weaning percentage, calving distribution, herd size, and investment. Family labor was used in the economic analysis. All financial factors analyzed were correlated to RLM (P

Two experiments were conducted to evaluate feedlot performance of heifers and calves and the lactational characteristics and carcass composition and quality of heifers while in the single-calf heifer (SCH) system. In Exp. 1, 24 lactating Angus × Holstein heifers were slowly adapted to an 85% concentrate diet, and one-half of the heifers were implanted with Finaplix-H®, both at 11 wk postpartum. Heifer-calf pairs were then placed in feedlot pens, equipped with pinpointer feeding devices, and fed an 85% concentrate diet for 102 d. The control (C) and implanted (I) heifers had similar (P=0.27) daily gains and similar (P=0.30) DMI; however, I heifers consumed 8.9% less (P

Two experiments were conducted to evaluate feedlot performance, lactational characteristics, and carcass composition and quality of heifers and the performance of their calves in a single-calf heifer (SCH) system. In Exp. 1, 13 [10 lactating (L) and 3 nonlactating (NL)] prenatally androgenized (PA) heifers, born to cows implanted with testosterone propionate (TP) and 19 (13 L and 6 NL) control (C) heifers, born to nonimplanted cows, were used. Heifers were calved and the pairs were placed in feedlot pens to evaluate the effects of PA on feedlot performance and lactation. Heifers were fed an 85% concentrate diet and fed to a compositional endpoint of 1.1 cm of subcutaneous fat cover, at which point calves were weaned and heifers slaughtered approximately 12 h later. The NL heifers consumed 17.0% less (P

Three trials were conducted to determine the effects of the changed USDA quality grade guidelines and finishing environment on the performance and carcass merit of Angus-sired and Wagyu-sired single-calving heifers. In trial 1, nine Angus and 15 Wagyu single-calving heifers were finished to a compositional subcutaneous fat cover of 1.0 cm on a corn/corn silage-based diet. Feedlot performance was not affected by sire breed. Wagyu (59.4 ± 0.49%) heifers had a higher ( P P P P P >0.10) lower as a result. Carcass merit was not significantly affected by finishing environment. The single-calving heifer system was a viable option for beef production despite the changes in USDA quality grade guidelines.

Trace minerals are the most variable of the nutrients commonly determined in feedstuffs. Most feed composition tables give an average value with no indication of the normal variation around the mean. Nutritionists and producers are often uncertain how to interpret feed analysis data that differ significantly from published values. Sources of variation associated with an individual sample include sampling error, soil or other contaminations, method of sample preparation, and lab to lab variation. Agronomic or management factors causing variation include: genus, species, or variety of crop; fertility, type, and mineral concentration of the soil; stage of plant maturity; and climatic or seasonal conditions. Maps describing specific regions of the country that are consistently deficient in one or more of the trace minerals are also included.

The National Research Council (NRC) feedstuff composition tables have been widely used by nutritionists, feed manufacturers and livestock producers. In spite of changes in crop varieties, soil fertilization practices and processing methods, there has been no systematic up-dating of the tables in recent years. A recent survey comparing the mineral concentrations of common feedstuffs as determined by commercial laboratories with NRC values showed marked discrepancies. For example, the sodium, copper, zinc and manganese concentrations determined by commercial laboratories were much lower than NRC values for several common feedstuffs. In addition, the standard deviations were often nearly equal to the mean values. For the NRC tables to continue as the standard, a systematic up-dating is required where a mean value, standard deviation and the number of samples analyzed is reported for each nutrient.

Eight ewe lambs (TE) born to ewes implanted with testosterone propionate between d 40 and 70 of gestation and 10 ewe lambs (CE) and 10 wether lambs (CW) from non-implanted ewes were used to measure the effects of prenatal androgenization on growth and metabolism. Starting BW (approximately 60 d of age) were not different among treatment groups. Finishing BW of TE and CW tended to be greater (P < .10) than those of CE; ADG of TE was 13% greater (P < .05) than ADG of CE. The DMI tended to be greater (P < .10) for TE than for CE but feed efficiency did not differ among treatments. Carcass weights were greater (P < .05) for CW than for CE. Subcutaneous fat, internal fat, and longissimus muscle area were not affected by sex or prenatal androgenization. Increases in glucose concentration in plasma from prefeeding to postfeeding were greater (P < .05) for CE than for TE or CW. The concentration of NEFA in plasma decreased (P < .05) from growing to finishing stages for TE and CW but remained constant for CE. Plasma glycerol concentration decreased more (P < .05) after feeding for TE and CW than for CE. Average concentrations of insulin (P < .01) and the increase of insulin after feeding (P < .05) were greater for TE and CW than for CE. The average concentration of urea N in plasma tended (P < .08) to be greater for CW than for TE or CE.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro measurements of metabolism were made in subcutaneous and perirenal adipose tissue (AT) and liver from prenatally androgenized ewe lambs (TE), control ewe lambs (CE), and control wether lambs (CW). In adipose tissue slices, release of glycerol or fatty acids into the medium was not different among treatments, but glycerol release was greater (P .1) of prenatal exposure to testosterone on mitochondrial protein content of liver, rates of mitochondrial state 3 or state 4 respiration, the ratio of ADP :oxygen in the presence of respiratory substrates, or hepatic contents of lipid, triglyceride, or glycogen. Protein content of liver was greater (P < .05) for CW than for CE ; TE were intermediate. Collectively, there were minimal modifications of in vitro metabolism in AT or liver attributable to prenatal androgenization or sex that would directly influence ADG and carcass composition.

Six mature wethers (BW 72 kg) with ruminal, duodenal, and ileal cannulas were fed a control (no added soybean meal [SBM]) diet or diets containing unheated SBM or SBM roasted at 165 degrees C for 75, 150, 180, or 210 min in a 6 x 6 Latin square experiment. Concentrations of indicators of heat exposure (ADIN, ADF, NDF) in SBM increased with increasing roasting time. Duodenal flows of total N, non-bacterial N, and SBM N increased (P.05) linearly with increased roasting time. Small intestinal (SI) digestibility (percentage entering SI) of total N and SBM N was influenced quadratically (P.05) by roasting time; SI digestibilities were modestly increased by heating SBM to 150 min, then declined dramatically when SBM was heated for 180 and 210 min. These responses resulted in a quadratic (P.05) increase in quantity of total and SBM N disappearing in the SI; quantities increased as SBM was heated to 150 min and remained unchanged when SBM was heated for 180 and 210 min. These responses resulted in a quadratic (P.05) increase in quantity of total and SBM N disappearing in the SI; quantities increased as SBM was heated to 150 min and remained unchanged when SBM was heated for 180 and 210 min. Duodenal flows and SI digestibilities of total and non-bacterial amino acids (AA) and of most individual AA followed patterns similar to those observed for N. Maximum quantities of total and individual AA disappeared from the SI when wethers were fed SBM roasted at 165 degrees C for 150 min. Evaluation of the effects of heat treatment on the nutritive value of a protein source for ruminants should include considerations for both ruminal protein escape and SI availability of escaped protein and for the nature of the AA supply absorbed from the SI.

Four experiments were conducted on the controlled delivery of testosterone propionate in cattle and sheep. Blood testosterone concentrations were more consistent across time when silicone implants were used for delivery than when compressed pellets were used for delivery. Heifers with high testosterone concentrations were infertile. Female offspring born to heifers exposed to a consistent delivery of testosterone propionate, beginning before and continuing throughout gestation, had normal female phenotype. Prenatally androgenized females were at least as fertile as untreated heifers. Combined, the four experiments demonstrate that 1) testosterone suppresses fertility of treated females, and 2) phenotypic masculinization and sterility of female offspring can be avoided when androgens are delivered prenatally by controlled release implants regardless of stage of gestation when treated.

Hydration of feeds and bacterial attachment to feed particles are thought to play major roles in rumen digestion of fibrous feedstuffs. The objective of the present study was to integrate these phenomena in a mechanistic model that could be used for data analysis. The proposed model was based on the conversion of biomass, where digestion end-products can be used for the synthesis of bacterial mass. Digestion of the potentially digestible fraction and subsequent accumulation of bacterial mass was based on a sequential, three-compartment model. These compartments represented substrate undergoing hydration, digestion, and bacterial mass accumulation. A fraction of the substrate was used for synthesis of bacterial mass. It was assumed that these bacteria associate either temporarily or permanently with the remaining substrate. Dacron bags containing either dry or fully-hydrated lucerne (Medicago sativa), maize (Zea mays) cobs, orchard grass (Dactylis glomeratd), and wheat straw were incubated in the rumen of a steer that was infused continuously with (15NH4)2SO4. The15N-enrichments of isolated particle-associated bacteria and residue remaining in the bags were used to estimate bacterial attachment. Substrate remaining and microbial mass accumulation were analysed simultaneously. Hydration did not appear to limit digestion. Fractional rate of digestion and appearance of attached bacterial mass was fastest for lucerne. For lucerne, 5 % of the digestion end-products were used for synthesis of bacteria that associated with the substrate, whereas for maize cobs, orchard grass, and wheat straw this was 16, 14, and 19% respectively. Less than 2% of digestion end-products were used for synthesis of bacteria that permanently remained associated with the substrate. Permanent association can occur only with the indigestible fraction, and probably represents bacterial debris. Lysis and/or detachment of bacterial cells was highest for lucerne, and was indicative of the rapid dynamics of lucerne digestion.

Although it is recognized that the potentially digestible fraction of substrates in the rumen is heterogeneous in composition, most deterministic models that describe ruminal in situ digestion assume existence of only one or two homogeneous fractions of potentially digestible material. Alternatively, a stochastic model based on heterogeneity of substrate has been developed, although its validity has not been determined. To evaluate such a model, alfalfa hay and wheat straw were physically fractionated by dry sieving. Dacron bags containing these fractions were incubated in the rumen of a steer and the residue that remained was analyzed sequentially for DM, NDF, ADF, ADL, and acid detergent insoluble ash. Digestion kinetics of chemical fractions were determined by simultaneous analysis of the digestion profiles of DM, NDF, ADF, ADL, and acid detergent insoluble ash. The weighted mean and variance of the fractional digestion rate constant were .083 h-1 and 4.7 x 10(-4) h-2 for alfalfa and .021 h-1 and 2.4 x 10(-5) h-2 for wheat straw, respectively. In contrast, fitting DM data to a stochastic model assuming heterogeneous rates, the mean and variance of the fractional digestion rate were .078 h-1 and 8.3 x 10(-11) h-2 for alfalfa and .018 h-1 and 5.3 x 10(-12) h-2 for wheat straw, respectively. Because the estimates of the variance approached zero for the stochastic model, it is implied that this model reduced to a model involving a single fractional digestion rate. It is concluded that parameter estimates obtained from a stochastic model do not necessarily have a biological meaning.

Rutherford backscattering spectrometry was used to study the diffusion of copper into three fully imidized polyimides of differing chemical structure, electrophilicity and T g . Samples were exposed to heat treatment in the different atmospheric environments of air, N 2 and vacuum (10 −8 Torr). The coefficients D of the diffusion of copper oxide into the polyimide hosts was −18 cm 2 s −1 when the samples were annealed under high vacuum conditions. In contrast, for samples annealed in a nitrogen atmosphere, the D value was orders of magnitude higher and its temperature dependence varied with T −1 . Under these conditions, comparable diffusivities of copper oxide were observed in each of the polyimides. Moreover, when the polyimide samples were annealed in air, still higher values of D were found. For these samples, however, we were able to show conclusively that the degradation of the polyimide was considerable.

The effects of configurational disorder and chain branching on the melting characteristics of the addition polymer poly(vinyl fluoride) (PVF) have been investigated. For PVF, the melting point (Tm) was found to be strongly dependent on polymerization temperature, and only weakly dependent on polymerization pressure. Structural investigation of the polymer backbone using 19F nuclear magnetic resonance analysis reveals that the pronounced increase in Tm results predominantly from a decrease in chain branching and, to a far lesser extent, from improved main-chain regio-regularity. For PVF with a (tertiary fluorine) branch-point content above 2.2% (∼ one branch per 45 monomer additions) the melting point is reduced to below 180°C, whereas for samples with branch-point content less than 0.3% (∼ one branch per 300 monomer additions) the melting point lies above 205°C. Moreover, for the same polymers, the number of head-to-head monomer linkages was found to remain largely constant (= 12.5 ± 1%).

An experiment was conducted to determine whether fractionation of substrate into a soluble fraction, a potentially digestible fraction, and an indigestible fraction is an intrinsic characteristic of substrate and, thus, not affected by the ruminal environment in which it is incubated. The soluble fraction disappears during washing and is, by definition, an intrinsic fraction. Ten substrates were incubated for 4 or 42 d in the rumen of steers fed either mature alfalfa hay or a concentrate diet. The ADF residue remaining after 42 d of incubation was consistently higher for steers fed the concentrate diet but was not affected by animal, indicating that the indigestible ADF fraction, per se, is not an intrinsic fraction of substrate. This implied that certain microbial digestive activity could be not only reduced, but even inhibited, by changing the ruminal environment. A data analysis method was proposed that accounted for existence of intrinsic fractions by simultaneously analyzing digestion profiles of a single substrate, incubated in different ruminal environments. These profiles shared a common beginning point, whereas asymptotic endpoints depended only on dietary treatment. In general, parameter estimates were similar to those obtained from individual analysis of the digestion profiles, but asymptotic standard errors were smaller.

Adipocyte differentiation is probably controlled by transcriptional and post-transcriptional regulation. Longissimus lumborum from Angus steers (aged 155 d; seven animals per diet) fed high-starch or low-starch diets for 112 d (growing phase) followed by a common high-starch diet for an additional 112 d (finishing phase) was biopsied at 0, 56, 112 and 224 d for transcript profiling via quantitative PCR of twenty genes associated with adipogenesis and energy metabolism. At 56 d steers fed high starch had greater expression of PPARγ as well as the lipogenic enzymes ATP citrate lyase (ACLY), glucose-6-phosphate dehydrogenase (G6PD), fatty acid synthase (FASN), fatty acid binding protein 4 (FABP4), stearoyl-CoA desaturase (SCD), glycerol-3-phosphate acyltransferase, mitochondrial (GPAM), and diacylglycerol O-acyltransferase homologue 2 (DGAT2), and the adipokine adiponectin (ADIPOQ). Expression of insulin-induced gene 1 (INSIG1) was also greater with high starch at 56 d. Steers fed low starch experienced a marked increase in FASN, FABP4, SCD, DGAT2 and thyroid hormone-responsive (SPOT14 homologue, rat) (THRSP) between 56 and 112 d of feeding. A greater expression of the transcription factors sterol regulatory element-binding transcription factor 1 (SREBF1) and MLX interacting protein-like (MLXIPL) was observed at 224 d in steers fed high starch, suggesting a nutritional imprinting effect. Carryover effects of low starch feeding were discerned by greater expression at 224 d of THRSP, FABP4, SCD and DGAT2. These steers also had greater PPARγ at 224 d. Despite these responses, low starch led to greater expression at 224 d of nuclear receptor subfamily 2, group F, member 2 (NR2F2), a known repressor of rodent adipocyte differentiation through its negative effects on PPARγ, ADIPOQ and FABP4. Results suggested that early exposure to high starch induced precocious intramuscular adipocyte proliferation and metabolic imprinting of lipogenic transcription regulators. Low starch might have blunted the PPARγ-driven adipogenic response through up-regulation of NR2F2 but the endogenous ligand for this nuclear receptor remains unknown.

Background Transcriptional networks coordinate adipocyte differentiation and energy metabolism in rodents. The level of fiber and starch in diets with adequate energy content fed to young cattle has the potential to alter intramuscular adipose tissue development in skeletal muscle. Post-weaning alterations in gene expression networks driving adipogenesis, lipid filling, and intracellular energy metabolism provide a means to evaluate long-term effects of nutrition on longissimus muscle development across cattle types. Results Longissimus lumborum (LL) from Angus (n = 6) and Angus × Simmental (A × S; n = 6) steer calves (155 ± 10 days age) fed isonitrogenous high-starch (HiS; 1.43 Mcal/kg diet dry matter; n = 6) or low-starch (LoS; 1.19 Mcal/kg diet dry matter; n = 6) diets was biopsied at 0, 56, and 112 days of feeding for transcript profiling of 31 genes associated with aspects of adipogenesis and energy metabolism. Intake of dietary energy (9.44 ± 0.57 Mcal/d) across groups during the study did not differ but feed efficiency (weight gain/feed intake) during the first 56 days was greater for steers fed HiS. Expression of PPARG increased ca. 2-fold by day 56 primarily due to HiS in A × S steers. Several potential PPARG-target genes (e.g., ACACA, FASN, FABP4, SCD) increased 2.5-to-25-fold by day 56 across all groups, with responses (e.g., FASN, FABP4) being less pronounced in A × S steers fed LoS. This latter group of steers had markedly greater blood plasma glucose (0.99 vs. 0.79 g/L) and insulin (2.95 vs. 1.17 μg/L) by day 112, all of which were suggestive of insulin resistance. Interactions were observed for FABP4, FASN, GPAM, SCD, and DGAT2, such that feeding A × S steers high-starch and Angus steers low-starch resulted in greater fold-changes by day 56 or 112 (GPAM). Marked up-regulation of INSIG1 (4-to-8-fold) occurred throughout the study across all groups. SREBF1 expression, however, was only greater on day 112 namely due to LoS in A × S steers. The lipogenic transcription factor THRSP was 6-to-60-fold greater by day 56 primarily due to HiS in A × S steers, constituting the greatest response among all genes. Conclusion Results involving gene markers of mature adipocytes (e.g., PPARG, THRSP, SCD) provided evidence of intramuscular adipose tissue differentiation during the early portion of the growing phase. The resulting gene networks underscored a central role for PPARG in controlling transcription of genes which are known to co-ordinately regulate adipocyte differentiation and lipid filling in non-ruminants. Unlike rodents, INSIG1 appears to play an important role in cattle muscle adipogenesis. We propose that a network of transcription regulators and nuclear receptors including PPARG-target genes, INSIG1, and THRSP, coordinate activation of adipocyte differentiation and lipid filling at an early age.

The effects of increasing dietary CP level on N retention (Exp. 1) and intestinal supply of amino acids (AA; Exp. 2) were studied in lambs fed diets based on alkaline hydrogen peroxide-treated wheat straw (AHPWS). Soybean meal (SBM) was substituted for corn to increase CP level in both experiments. In Exp. 1, an incomplete design for the two-way elimination of error was used to allot 24 ram lambs (mean BW = 25 kg) within breed to six CP levels (6, 8, 10, 12, 14, and 16% of DM). Neutral detergent fiber digestibility and N retention increased quadratically (P = .06 and P less than .01, respectively) with increasing CP level. Nitrogen retention, expressed as a percentage of N intake, was greatest for lambs fed 12% CP (20.7%) but was greatest for lambs fed 14% CP when expressed as grams per day (4.0 g/d). In Exp. 2, five multicannulated St. Croix lambs (34 kg) were used in a 5 x 5 Latin square design. Treatments were 8.5, 11, 13.5, 16, and 18.5% dietary CP. Chromic oxide was used as a digesta flow marker and purines were used as a bacterial marker. Protein level had no effect on extent of dietary CP degradation in the rumen (69 +/- 3.2%). True ruminal OM digestibility increased (P less than .01) linearly and ruminal fluid NH3 N concentration increased (P less than .01) quadratically with increasing CP level. Total, bacterial, and nonbacterial N and AA flows to the duodenum increased (P less than .05) linearly with increasing CP level. Duodenal AA profile (g/100 g total AA) was altered slightly. The essential AA valine, isoleucine, phenylalanine, lysine, and arginine increased (P less than .05) and methionine decreased (P less than .05) in proportion to other AA with increasing CP level. Flows of all essential AA increased with increasing CP level. Apparent small intestinal N and AA disappearance increased linearly (P less than .05) and apparent total tract N digestibility increased (P less than .01) quadratically with increasing CP level. These data are interpreted to indicate that maximal N retention and fiber digestibility in diets based on AHPWS are obtained at 12% CP, even though the intestinal supply of AA continues to increase with increasing CP level. Supplementation of diets based on AHPWS with an extensively degraded protein source (SBM) does not substantially alter the profile of AA entering the duodenum compared to the AA profile of bacterial protein.

Two experiments were conducted to evaluate alkaline hydrogen peroxide-treated wheat straw (AHPWS) in cattle growing (Exp. 1) and finishing (Exp. 2) diets. In Exp. 1, 162 crossbred steers (257 kg) were fed 66% roughage diets in an 84-d growth trial to compare AHPWS to corn silage (CS) and to evaluate different supplemental CP sources and levels. A completely randomized design with a 3 x 3 factorial arrangement of treatments was used. Factors were roughage source (CS, a 1:1 mixture of CS:AHPWS [MIX] and AHPWS) and CP treatment (13 and 11% CP with supplemental CP provided by soybean meal [13-SBM] and [11-SBM] and 11% CP with a combination of urea, corn gluten meal, and fish meal [UGF]). Lasalocid was fed at the rate of 200 mg per steer daily. Steers fed AHPWS had decreased (P less than .01) DMI compared with steers fed MIX and CS. This may be due to increased dietary Na from residual Na in AHPWS. With each incremental increase in AHPWS, ADG and gain/feed decreased (P less than .01). Dry matter intakes (kg/d), ADG (kg), and gain/feed for CS, MIX, and AHPWS were 8.0, 1.56, and .19; 8.2, 1.33, and .16; and 7.5, 1.08, and .14, respectively. Decreased performance by steers fed AHPWS may be due, in part, to a negative interaction between the lasalocid and dietary minerals. There were no differences in performance due to CP supplementation. In Exp. 2, AHPWS was compared to alfalfa hay (AH) and CS at 10 and 20% of dietary DM (2 x 3 factorial) in a 127-d finishing trial with 108 crossbred steers (341 kg).(ABSTRACT TRUNCATED AT 250 WORDS)

In contrast to digestion models that include a discrete lag phase, a compartmental digestion model was proposed. It assumed the existence of a lag compartment and a digestion compartment. Substrate present in the digestion compartment was subject to first-order kinetics digestion. Flow of substrate from the lag compartment to the digestion compartment was proposed to be a first-order process and likely was affected by hydration of substrate, bacterial attachment, and colonization. The proposed model was compared with models that assumed the existence of a discrete lag phase. Parameter estimates for these models were obtained either through logarithmic transformation of data or nonlinear regression. Statistically, there was no difference between the compartmental model and the nonlinear model with a discrete lag phase. Differences in parameter estimates between these two models were small. Residual mean squares were higher for the logarithmically transformed models. Differences in parameter estimates between these models and the compartmental model depended on the structure of the experimental data. In a number of cases, the nonlinear parameters of the compartmental model converged to the same value, resulting in a different interpretation of the model. Residual mean squares for predicting rate of disappearance were lowest for the compartmental model.

Details of the molecular organization occurring during imidization of the poly(amic acid)PMDA-12C at temperatures below the bulk melting point were examined. The effects of surface constraints were investigated by studying structural evolution in thin droplets. The results showed the development of surface roughness and fluctuations in mass thickness, as well as the presence near the droplet edge of discrete crystallites containing uniformly spaced 1.8-nm (001) fringes, which correspond to the repeat distance along the polymer backbone. The projected size, shape, orientation and relative population of the crystallites were analyzed quantitatively

Four Simmental steers with ruminal, duodenal, and ileal cannulas were used to examine effects of dietary forage: concentrate ratio and supply of ruminally degradable true protein on site of nutrient digestion and net ruminal microbial protein synthesis. Steers (345 kg) were fed ammoniated corn cob (high forage; HF)- or corn cob/ground corn/cornstarch (low forage; LF)-based diets supplemented with soybean meal (SBM) or a combination of corn gluten meal and blood meal (CB). Diets were fed at 2-h intervals with average DM intake equal to 2.2% of BW. Feeding LF vs HF increased (P less than .05) OM digestion (percentage of intake) in the stomach, small intestine, and total tract. Efficiency of microbial CP synthesis (EMCP; g of N/kg of OM truly fermented) decreased (P less than .05) for LF vs HF (24.1 vs 26.8), but microbial N and total N flows to the small intestine were similar (P greater than .05) between energy levels (average 112 and 209 g/d, respectively). Total N flows to the small intestine were 13.1% greater (P less than .05) for CB than for SBM because of increased (P less than .05) passage of nonmicrobial N. Feeding SBM vs CB increased (P less than .05) EMCP (27.3 vs 23.3) and microbial N flow to the small intestine (127.5 vs 112.5 g/d), but these increases were not likely due to increased ruminal concentrations of ammonia N (NH3 N). Decreased (P less than .05) incorporation of NH3 N into bacterial N and slower turnover rates of ruminal NH3 N for SBM vs CB suggest that direct incorporation of preformed diet components into cell mass increased when SBM was fed. Results of this study suggest that the inclusion of ruminally degradable protein in the diet may increase the supply of products from proteolysis and that this can increase EMCP and microbial protein flow to the small intestine.

Thermal stimulated current depolarization was used to investigate dielectric relaxations in crazed and uncrazed films of polystyrene and poly(4-bromostyrene). For highly crazed samples of both polymers a significantly enhanced dielectric signal was found at temperatures nearly 100°C below the bulk T g . Partial healing of the crazed samples, by heating to temperatures 10-20°C below T g , was found to markedly decrease the magnitude of the enhanced low-temperature relaxation. Additionally, for fully healed crazes a complete disappearance of this relaxation was found

Two experiments were conducted to determine the effects of inclusion of alkaline hydrogen peroxide-treated oat hulls in diets on feed intake and nutrient digestion by wethers and growing heifers. In a pilot study with six wethers, we compared diets with untreated versus treated oat hulls containing 60% roughage and 40% concentrate (DM basis). Holstein heifers (n = 12) were used in three replications of a 4 x 4 Latin square design to compare diets containing 10% concentrate and 0 (control), 20.4 (low), 40.6 (medium), and 60.5% (high) treated oat hulls with the remainder being alfalfa haylage DM basis). Digestibilities of DM, NDF, and ADF were increased by at least 12 percentage units, and digestible nutrient intakes increased 73 g/d for wethers fed the treated oat hull diet versus the untreated diet. Intakes of DM by heifers were 8.9, 9.4, 9.6, and 9.2 kg/d for the control, low, medium, and high treated oat hull diets, respectively. Apparent digestibilities of DM, OM, NDF, and ADF were increased by 7.1, 6.7, 24.5, and 10.5 percentage units, respectively, for the high oat hull versus control diet. Gains in BW ranged from .77 kg/d for heifers fed the high diet to 1.1 kg/d for those fed the medium diet. Heifers fed larger amounts of treated oat hulls had lower ruminal pH and ammonia N concentrations, higher molar percentage acetate, and greater acetate:propionate ratios than controls. Heifers fed diets containing treated oat hulls had higher digestible DM and fiber intakes than controls. Treated oat hulls have a place in diets of growing ruminants.

Twelve Holstein cows, averaging 110 d postpartum, were used in three replications of a 4 x 4 Latin square design to determine the effects of feeding different amounts of alkaline hydrogen peroxidetreated oat hulls on digestion and production responses. Complete mixed diets were 35% concentrate (DM basis) with varying amounts of treated oat hulls, alfalfa haylage, and corn silage as forage (65%). Treatments were 0 (control), 17.2 (low), 34.5 (medium), and 52.1% (high) treated oat hulls in the diet. Dry matter intake was 24.6, 27.1, 27.7, and 26.3 kg/d for the control, low, medium, and high treatments, respectively. Apparent digestibilities of DM, OM, and ADF were not affected by diet, but NDF and CP digestibilities were increased 15.6 and 6.9 percentage units, respectively, by feeding the largest amount of treated oat hulls compared with the control. Yields of milk, 4% FCM, and milk fat, protein, and SNF were highest for the diets that contained low and medium treated oat hulls. There were decreases in milk protein percentage (from 3.19 to 3.07%) and a trend towards increased milk fat percentage (from 3.53 to 3.63%) as the amount of treated oat hulls increased. Cows fed larger amounts of treated oat hulls had lower ruminal concentrations of total VFA with greater acetate:propionate ratios. Cows fed diets containing treated oat hulls had greater DM intakes and yields of 4% FCM and milk fat compared with those fed the control diet containing traditional forage sources.

Five studies were conducted to determine nutrient digestibility and performance of lambs and steers fed thermochemically treated crop residues and distillers dried grains with solubles (DDGS) as a corn replacement pellet (CRP; 75% residue:25% DDGS, DM basis). Fifteen Hampshire, Suffolk, or Dorset wethers (BW 33.3 +/- 5.0 kg) were utilized to evaluate nutrient digestibility of the unprocessed native (NAT) and CRP [Exp. 1: wheat straw (WS); Exp. 2: corn stover (CS); Exp. 3: switchgrass (SWG) and corn fiber:wheat chaff (CFWC)] when limit fed (Exp. 1 and 2: 1.8% of BW daily; Exp. 3: 2.5% of BW daily) compared with a 60% corn diet. In Exp. 4, 56 individually fed Dorset-cross wether lambs (BW 32.0 +/- 1.4 kg) were utilized to compare performance and digestibility of WS, wheat chaff (WC), corn fiber (CF), a 3:1 blend of corn fiber:wheat straw (CFWS), a 3:1 blend of CFWC, and SWG-CRP fed for ad libitum intake compared with a 45% corn diet. In Exp. 5, 32 individually fed Holstein steers (BW 185.2 +/- 0.9 kg) were used to evaluate performance and digestibility of diets containing corn, WS-CRP, CFWC-CRP, or NAT-WS fed for ad libitum intake. Crop residues were processed with 5% calcium oxide (DM basis) and 35% water in a double-shaft enclosed mixer (Readco Kurimoto Continuous Processor, York, PA) and subsequently pelleted with DDGS to form CRP. Feeding lambs WS-CRP (Exp. 1) or CS-CRP (Exp. 2) increased digestion of DM, NDF, and ADF compared with NAT (P < 0.05). In Exp. 3, feeding CFWC-CRP increased total tract NDF digestibility and ADF digestibility (P < 0.05). Experiment 4 final BW were greatest for control lambs and least for lambs fed CFWS-CRP or SWG-CRP. Body weight gains for lambs fed CRP averaged 15.9% less than control (P < 0.05). Lambs fed CRP diets had greater (P < 0.05) NDF and ADF intake and output. In Exp. 5, steers fed the corn or 2 CRP diets gained similarly and faster (P < 0.05) than those fed the NAT-WS diet. Steers fed the control corn diet were more efficient (P < 0.05) than steers fed other treatments. Steers fed the corn diet, CFWC-CRP, and WS-CRP had greater (P < 0.01) DM digestibility than NAT. The results confirm benefits for nutrient digestion and subsequent animal performance when crop residues are thermochemically processed. Processed crop residues may be fed in combination with DDGS to partially replace corn in ruminant diets.

Publisher Summary Soybean Meal (SBM) is the number-one protein source used in the poultry and livestock industries throughout the world. Of all the SBM that is sold in the United States, >50% is used in diets fed to poultry and 26% is used in diets fed to swine. Ruminant animals, dogs, cats, and others account for the remaining portion of this usage. The main reason for the popularity of SBM is the unique composition of Amino Acids (AAs) that complements the AA compositions of many cereal grains. The excellent AA quality in SBM is also the reason why SBM is increasingly being used in the pet-food industry. While SBM is by far the most popular soybean product in livestock diets, other products are also being used to a varying degree. These products include full-fat soybeans, Soy Protein Concentrate (SPC), Soy Protein Isolate (SPI) soy-bean oil, and soybean hulls. Each of these products has unique nutritional properties that make them appropriate for inclusion in diets fed to certain categories of animals. This chapter provides a summary of the current knowledge about the nutritional values of soybean products fed to poultry, livestock, and companion animals.

Twelve Holstein cows, averaging 34 d postpartum, were used in three replications of a 4 x 4 Latin square design to determine the effects of feeding different levels of alkaline hydrogen peroxide-treated wheat straw on digestion and production responses in lactating dairy cows. Complete mixed diets consisted of 50% concentrate (DM basis) plus varying proportions of treated wheat straw, alfalfa haylage, and corn silage as the forage source. Treatment contained 0 (control), 12.5 (low), 25.0 (medium), or 37.5% (high) treated wheat straw in the diet. Dry matter intakes were 18.5, 17.2, 17.4, and 16.7 kg/d for the four treatments, respectively. Apparent digestibilities of DM and OM were decreased (approximately 4.4 percentage units), and NDF and ADF digestibilities were increased by 9.4 and 3.0 percentage units, respectively, with the high wheat straw diet. Yields of milk and 4% FCM, and SNF percentage did not differ among the treatment groups. Milk fat percentage increased (from 3.07 to 3.32%) and milk protein percentage decreased (from 2.61 to 2.56%) as the proportion of treated wheat straw increased in the diet. Cows fed the higher proportions of treated wheat straw had increased ruminal concentrations of total VFA and molar percentage acetate but a decreased molar percentage propionate, resulting in a greater acetate to propionate ratio. Cows fed the low and medium wheat straw diets had slightly lower DM intakes but production responses were similar to cows fed the control diet containing alfalfa haylage and corn silage as fiber sources.