Translational termination in Escherichia coli: three bases following the stop codon crosslink to release factor 2 and affect the decoding efficiency of UGA-containing signals

We conducted experiments to determine whether lambs fed grain prefer foods and solutions containing sodium bicarbonate (NaHCO3) and lasalocid, compounds capable of attenuating acidosis. In Exp. 1, we determined whether lambs fed barley preferred flavored rabbit pellets (RP) containing NaHCO3 and lasalocid. Lambs in two groups (n = 10/group) were fed increasing amounts of barley on d 1 to 12 (300 to 1,100 g) and again on d 23 to 34 (300 to 1,350 g). After ingesting barley on d 1 to 12, lambs were fed ground RP containing lasalocid and NaHCO3 (i.e., medicated) and flavored with either 2% onion (group 1) or 2% oregano (group 2). During d 23 to 34, lambs were fed unmedicated RP containing NaCl and flavored with either 2% oregano (group 1) or 2% onion (group 2). During preference tests on d 35 to 40, lambs fed grain preferred RP with NaHCO3 to RP with NaCl (151 vs. 96 g; P < .01). In the Exp. 2, we determined whether wheat ingestion affected consumption of aqueous solutions containing NaHCO3. In trial 1, 28 lambs were assigned to four treatments: 1) low-wheat + 2% NaHCO3, 2) high-wheat + 2% NaHCO3, 3) low-wheat + water, and 4) high-wheat + water. For 12 d from 0800 to 0830, lambs in treatments 1 and 3 were fed 300 g of wheat and lambs in treatments 2 and 4 were fed up to 1,300 g of wheat; fluids (NaHCO3 and water) were then offered from 0930 to 1230 daily. Lambs drank more NaHCO3 on the high- than on the low-wheat diet (1,332 vs 890 g; P = .03); water consumption was similar for lambs on the high- and low-wheat diets (1,675 vs 1,700 g; P > .10). In trial 2, lambs in treatments 3 and 4 were offered a solution containing 1.4% NaCl. For 13 d from 0800 to 0830, lambs in treatments 1 and 3 were fed 500 g of wheat and lambs in treatments 2 and 4 were fed up to 1,700 g of wheat. Lambs had access to fluids from 0800 to 1200 daily. Lambs drank nearly twice as much NaHCO3 solution on the high- than on the low-wheat diet (1,066 vs 572 g), whereas they drank only 1.4 times more NaCl solution on the high- than on the low-wheat diet (888 vs. 634 g; P < .001). Fewer lambs showed signs of acidosis in treatment 2 than in treatment 4 in trials 1 (2 vs 9) and 2 (7 vs 17). Collectively, these results are consistent with the hypothesis that lambs fed grain prefer substances that attenuate acidosis.     

The effect of grain source and grain processing on performance of feedlot cattle: a review

Effects of grain species and grain processing method on DMI, rate and efficiency of gain, and feeding value for cattle fed high concentrate diets were appraised by statistically compiling results from 605 comparisons from feeding trials published in North American journals and experiment station bulletins since 1974. Metabolizable energy (ME) values for each grain and processing method were calculated by quadratic procedures from DMI and animal performance. Averaged across processing methods, ME values for corn, milo, and wheat grain (3.40, 3.22, and 3.46 Mcal/kg DM) fell within 9% of ME estimates from NRC (1996) for beef cattle. In contrast, ME values for barley and oats grain (3.55 and 3.46 Mcal/kg DM) were 24% and 17% greater than NRC (1996) estimates. Compared with the dry rolled forms, high moisture corn and milo resulted in lower ADG and DMI. Compared with dry rolling, either steam rolling or flaking of corn, milo, and wheat decreased DMI without decreasing ADG and improved feed efficiency by 10, 15, and 10%, respectively. Compared with dry rolled grain, steam flaking increased (P < .05) body weight-adjusted ME of corn and milo grain by 15 and 21%, respectively; body weight-adjusted ME for whole corn was 9% greater (P < .05) than for rolled corn grain. Steam flaking was surprisingly effective (13%) at increasing (P < .05) the body weight-adjusted ME of wheat, but steam flaking failed to increase the ME of barley and oats. Higher moisture content of high-moisture corn decreased dry matter intake without depressing ADG and improved efficiency and increased ME of the grain. Compared with steam flakes of moderate thinness, processing milo or barley to a very thin flake tended to reduce ADG and failed to improve feed efficiency. The ideal roughage source and roughage moisture content for maximum ME and ADG varied with grain processing method. Feeding corn silage rather than alfalfa and wet rather than dry roughage depressed (P < .01) ADG of cattle and reduced (P < .01) body weight-adjusted ME of cattle fed high-moisture corn grain but tended to increase both with steam-flaked corn or wheat.     

Relationships among ewe milk production and ewe and lamb forage intake in Suffolk and Targhee ewes nursing single or twin lambs

Suffolk and Targhee ewes (30 each) with single or twin lambs were used in four periods beginning in late gestation and continuing through weaning to evaluate breed differences in milk production, lamb BW, and DMI by ewes and lambs. In Periods 1 (late gestation) and 2 (early lactation), ewes (Period 1) and ewes with lambs (Period 2) were individually penned, fed .45 kg of barley x ewe(-1) x d(-1) and allowed ad libitum access to chopped alfalfa. Ewes and lambs grazed native range in Periods 3 and 4. Grazed forage DMI was estimated using chromic oxide. Estimates of milk production were obtained by handmilking. Average lamb age was 4, 45, and 73 d at the beginning of Periods 2, 3, and 4, respectively. Milk production tended (P = .20) to be greater for Suffolk than for Targhee ewes. Targhee ewes produced 85% more (P = .001) wool than Suffolk ewes. From 33 d prepartum to 89 d postpartum, Suffolk ewes consistently weighed more (P = .001) than Targhee ewes. Suffolk ewe BW loss (-.15 kg/d) was greater (P = .01) than Targhee ewe BW loss (-.02 kg/d) from 33 d prepartum to 6 d postpartum. From 6 to 89 d postpartum BW gain did not differ (P = .69; .05 kg/d) between breeds. From birth to 89 d postpartum, Suffolk lambs consistently weighed more than Targhee lambs (P = .003). From birth to 89 d postpartum, ADG was greater for Suffolk than for Targhee lambs (P = .006). Targhee ewes consumed 25% more (P = .01) feed over the course of the study than did Suffolk ewes. Grazed forage DMI by Targhee lambs was 26% greater (P = .01) than DMI by Suffolk lambs. When meat production is the primary income from sheep, one potential advantage of Suffolks compared with Targhees is more rapid gain with less feed intake.     

Effects of fish meal and sodium bentonite on daily gain, wool growth, carcass characteristics, and ruminal and blood characteristics of lambs fed concentrate diets

We evaluated the effects of replacing some soybean meal (SBM) protein with fish meal (FM) protein in diets adequate and slightly deficient in CP, with or without .75% sodium bentonite (NaB) on performance and ruminal and blood metabolites of individually fed Suffolk lambs. Diets were based on corn, SBM, and cottonseed hulls. In Exp. 1, five lambs were assigned to each of the three dietary treatments (11% CP with 3% FM, 13% CP with 0 or 3% FM). Lambs fed diets that contained 11% CP with 3% FM or 13% CP with 0% FM had similar DMI and ADG. Gain and feed efficiency were slightly improved (P = .18) by the 13% CP diet with 3% FM. In Exp. 2, 32 lambs were assigned to four dietary treatments (13.5% CP of DM) in a 2 x 2 factorial arrangement (0 or 3% FM, and 0 or .75% NaB on an as-fed basis). The DMI and ADG were increased (P < .05) by FM and NaB supplementation. Interactions (P < .05) revealed that NaB increased DMI, ADG, gain per feed (g/kg of DMI), and plasma urea N concentration in the absence of FM but not in the presence of FM in the diet. Neither FM nor NaB influenced (P = .25) wool growth. Total ruminal VFA were increased (P < .06) by FM and NaB. Differences in mineral content of phalanx bone, liver, and kidney were small and may be related to the mineral content of diets and the effect of NaB on mineral solubilities. Similar DMI and ADG of lambs fed FM and NaB separately and in combination suggest that their beneficial effect is not additive.     

Serum folic acid in anticonvulsant long term therapy (author''s transl)

Forty Holstein heifer calves were assigned at random among four dietary treatments: 1) an all-concentrate ration; 2) a pelleted complete ration of 20% alfalfa and 80% concentrate; 3) concentrate and alfalfa pellets fed separately, free-choice; and 4) concentrate and long-stem alfalfa hay fed separately, free-choice. Treatment diets were continued for 12 wk. Calves fed the concentrate only had reduced weight gains, feed intakes, and poorer feed efficiencies compared to treatments 2 and 4. Calves fed long-stem alfalfa hay as a roughage consumed more feed and had larger weight gains than calves fed alfalfa pellets as a roughage free-choice. The pelleted complete ration containing 20% alfalfa was comparable to a ration containing long-stem alfalfa hay free-choice for weight gains and feed efficiencies. The digestibility of dry matter and crude protein of the pelleted complete feed was similar to the digestibility of equal amounts and proportions of concentrate and alfalfa pellets fed separately. Thus, when fed free choice to early-weaned calves, pelleted alfalfa is inferior to long-stem hay for stimulating intake of dry matter. However, increasing the proportion of alfalfa pellets in a complete ration compensates for its partial loss of efficacy for elevating feed intake and growth rates.     

Effect of the protein matrix on the digestion of cereal grains by ruminal microorganisms

Experiments were conducted to investigate the role of the protein matrix in the digestion of barley and corn by ruminal microorganisms. Grains, ground and collected on sieves as two particle fractions .25 to .89 mm (small particles) and 2.00 to 3.00 mm (large particles), as well as isolated barley and corn starch granules, were incubated with ruminal inocula. For both grains, digestion of starch in small particles was greater (P < .001) than that of large particles. At 16 and 24 h starch digestion was greater (P < .01) in barley than in corn, for small and large particles. Digestion of barley starch granules did not differ (P > .05) from that of corn starch granules at any incubation time. A 4-h preincubation of small-particle corn and barley with protease increased (P < .001) microbial digestion of starch in corn at 16 h but did not affect digestion of barley. When four ruminally cannulated steers were fed diets containing 80% barley, corn, or wheat or 100% alfalfa hay in a 4 x 4 Latin square experiment, amylolytic activity of ruminal inoculum was higher for steers fed grains than for those fed alfalfa. However, when standardized for total viable counts of bacteria, ruminal amylolytic activity did not differ (P > .05) among diet treatments, but proteolytic activity of ruminal inoculum for steers fed alfalfa was higher (P < .01) than that for steers fed cereal grains. Activity of serine proteases in ruminal inoculum was higher (P < .05) for steers fed alfalfa than for steers fed grains.(ABSTRACT TRUNCATED AT 250 WORDS)     

Timothy grass or alfalfa silage for cows in midlactation: effect of supplementary barley

Twenty-four multiparous Holstein cows averaging 104 d of lactation were used in a trial with a split-plot design to evaluate the nutritive value of two silages, timothy grass or alfalfa, both treated with formic acid and stored in plastic bag silos. Silages were offered for ad libitum intake either alone or with 17 or 34% (dry matter basis) dry-rolled barley. Both silages contained similar amounts of acid detergent fiber (ADF) (27.5 and 26.7% for timothy grass and alfalfa, respectively). After 110 d of storage, alfalfa silage contained higher amounts of organic acids and NH3 N but had lower soluble N. Total dry matter intake (DMI) and silage DMI were similar between cows fed both silages. Increased barley proportion decreased silage DMI (19.2 to 14.2 kg/d). Apparent total tract digestibility of dry matter was unaffected by treatment. The digestibility of neutral detergent fiber and ADF was higher for the timothy grass silage than for alfalfa silage and was unaffected by the barley percentage added to either silage. Milk yield was lower (23.9 to 22.6 kg/d) for cows fed the highest proportion of barley. The 4% fat-corrected milk yield was unaffected by treatment. Percentages of fat, protein, and total solids in milk were higher for cows fed diets with the higher barley content. Milk fat and protein yields were similar among treatments. Urea in blood was lower for cows fed timothy grass silage than for cows fed alfalfa silage (4.68 vs. 6.23 mg/100 ml). These results suggest that timothy grass silage and alfalfa silage, when stored at a similar ADF content, have comparable nutritive value for midlactation cows.     

Effect of wet corn gluten feed, supplemental protein, and tallow on steer finishing performance

Two trials evaluated the effects of level of wet corn gluten feed (WCGF), type of supplemental protein, and supplemental tallow on steer finishing performance. In Trial 1, WCGF was fed at 0, 25 (two diets), or 50% of the dietary DM replacing dry-rolled corn (DRC), molasses, and a portion of the supplement. The DRC control diet and one 25% WCGF diet were supplemented with a combination of protein sources. The second 25% WCGF diet was supplemented with urea alone. The 50% WCGF diet contained no additional protein supplementation. No differences in DMI (P > .10) were observed. Calves fed 25% WCGF plus a combination of protein sources or 50% WCGF gained faster (P < .10) and more efficiently (P < .10) than calves fed the DRC control. Calves fed 25% WCGF plus urea gained faster (P < .10) and tended (P = .14) to be more efficient than calves fed the DRC control. In Trial 2, WCGF was fed to replace 0 or 50% of the DRC and the molasses-urea supplement (DM basis). Both diets were fed with or without 3% tallow. Steers fed WCGF gained faster (P < .01) and more efficiently (P < .01) than steers fed DRC. Inclusion of 3% tallow increased gain (P < .05) and improved efficiency (P < .05). Feed efficiency is improved by the addition of WCGF or tallow to DRC finishing diets.     

A comparison of the effects of feeding concentrate diets, based on either maize or barley, or dried grass on adipose tissue lipogenesis in sheep

1. Three groups of 4 sheep were penned individually and provided with diets composed of either dried grass, 80% ground maize/20% soyabean meal or 80% ground barley/20% soyabean meal. 2. The diets were fed ad libitum for 3 weeks before s.c. adipose tissue biopsy samples were taken from the rump region. 3. Although the rate of lipogenesis was significantly increased by concentrate feeding the order of utilization of the various substrates was always acetate greater than glucose greater than lactate. Throughout this work lactate was always of minor significance as a lipogenic substrate. 4. The diet-induced differences in lipogenesis were reflected in significant increases in the specific activities of the fatty acid synthetase system, glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase in concentrate fed animals. 5. No differences were observed in in vitro lipogenesis from any of the substrates or enzyme specific activity between the 80% barley diet and the 80% maize diet. 6. These results are discussed in relation to the effect of concentrate and roughage feeding on the entry of alpha-linked glucose polymer into the small intestine of sheep.     

Plasma concentration of thyroid hormones in lambs fed poultry offal meal in replacement of soybean meal at two energy levels

Sixty growing Najedi ram lambs (23.5 kg BW: 3 months old) were divided randomly to 6 equal groups. Each group was fed on different (isonitrogenous) diet, being either high energy (2.79 Mcal ME/kg DM) or low energy (2.15 Mcal Me/kg DM), supplemented with either 0.5 or 10% poultry offal meal (POM) in replacement of an equal amount of soybean meal (SBM). Feeding was ad libitum for 15 weeks experimental period. Thyroid hormones levels in plasma were determined during the last 7 weeks of the experiment and were related to feed intake and body weight during the same period. Lambs fed high-energy diets showed higher (P < 0.01) levels of both thyroxine (T4) and triiodothyronine (T3) compared to those fed low-energy diets leading to lower T4 to T3 ratios. There was more conversion of T4 to T3 for more utilization of food by the lambs fed the 10% POM diet of the high-energy content.     

Influence of predeprivation diet nutrient density and sodium chloride content on nutrient losses and repletion in lambs

Six crossbred lambs (32+/-2 kg) in a 6 x 6 Latin square design were used to determine the effects of predeprivation diet nutrient density and NaCl content on nutrient losses during periods of feed and water deprivation and nutrient repletion. Treatments consisted of two predeprivation dietary nutrient densities (low [LOW] and moderate [MOD]) and three NaCI intakes (0, 2, or 4 g/d) in a 2 x 3 factorial arrangement. During the 4-d predeprivation phase, lambs fed the M0D diet had greater (P < .05) K retention and lower (P < .01) Na retention than lambs fed the LOW diet. Retention of Na increased linearly (P< .01), whereas retention of K decreased linearly (P < .O01) with increasing NaCl intakes. During the 3-d deprivation phase, lambs fed the MOD diet had lower (P < .01) Na losses than lambs fed the LOW diet. Losses of Na increased linearly (P < .01), whereas losses of K decreased linearly (P < .05) with increasing NaCl intakes. During the predeprivation and deprivation phases, cumulative losses of K were greater (P < .05) and cumulative losses of Na were lower (P < .05) in lambs fed the LOW diet than in lambs fed the MOD diet. Cumulative losses of K increased linearly (P < .05) as predeprivation NaCl intake increased. Predeprivation NaCl intakes did not affect (P > .10) total retention of water, Na, or K for the overall 14-d sampling period. Predeprivation salt intakes affected Na and K losses during a simulated marketing-transport period. However, after 7 d on the realimentation diet, predeprivation diet nutrient density and NaCl intake did not affect the balance of these nutrients.     

Biogenic amines in silage, apparent postruminal passage, and the relationship between biogenic amines and digestive function and intake by steers

A 4 x 4 Latin square experiment was conducted to examine abomasal passage of biogenic amines in steers fed silage and their related effects on intake, digestibility, and digestive function. Thirty percent of the dry matter (DM) in the diets consisted of alfalfa forage, which was fed as either hay or silage. The DM from alfalfa silage DM was substituted at 0, 33, 67, and 100% for DM from alfalfa hay and was fed to four ruminally and abomasally cannulated steers. The roughage component of the diet constituted 50% of the DM and consisted of 60% alfalfa silage or hay and 40% tropical corn silage. The concentrate was composed mainly of ground corn. The concentrations of putrescine and cadaverine in abomasal digesta increased as alfalfa silage in the diet increased. Abomasal recovery of biogenic amines, a product of their concentration in abomasal digesta and the passage of DM through the abomasum, was negatively correlated with intake. Abomasal recovery of most amines was 5 to 20% of intake. Abomasal recovery of cadaverine was correlated with depressed intake. Total DM intake was reduced 8.3 to 25.8% as the proportion of alfalfa silage in the diet increased. Frequency of reticular contractions, intake, ruminal DM digestibility, ruminal outflow, volatile fatty acids, and total tract DM digestibility decreased in steers fed diets that contained more alfalfa silage. Ruminal fluid pH and NH3 concentration increased in steers fed more alfalfa silage; however, mass and the DM percentage of ruminal contents decreased linearly. Postprandial insulin concentrations were quadratically related to the proportion of alfalfa hay or silage in the diet. Intraruminal metabolism of biogenic amines is extensive based on the relatively low quantities recovered in abomasal digesta; however, the amounts recovered in abomasal digesta were related to intake depression and associated physiological effects.     

Effects of fish meal in beef cattle diets on growth performance, carcass characteristics, and fatty acid composition of longissimus muscle

We investigated the effects of fish meal (FM) in beef cattle diets on growth performance, carcass characteristics, and fatty acid (FA) composition of longissimus muscle in 63 yearling steers (335 +/- 23 kg). High-moisture corn and alfalfa silage diets were supplemented with either a corn gluten/blood meal mixture or FM at 10% of the diet. Fish meal contained (as-is basis) 5.87 g/kg eicosapentaenoic acid (EPA) and 9.84 g/kg docosahexaenoic acid (DHA). Seven strategies were developed to feed either a control diet (no FM) or diets containing 5 or 10% FM with FM fed for either 56, 112, or 168 d before slaughter. Average daily gain and feed efficiency were not affected (P > .10) by FM feeding but DMI decreased. Within FM diets, cattle fed 5% FM consumed more (P < .01) DM and gained more (P < .02) than cattle fed 10% FM. Carcass traits were not affected (P > .05) by feeding strategy except for fatter (P < .05) and lower (P < .06) yielding carcasses in cattle fed 5 vs 10% FM diets. Fish meal feeding increased (P < .01) concentrations of (n-3) FA, including EPA and DHA, and decreased (P < .05) concentrations of arachidonic acid. Increasing the amount of dietary FM further increased (P < .01) concentrations of EPA and DHA and decreased (P < .05) concentrations of (n-6) FA. We estimate that a 114-g steak from cattle fed 10% FM would supply 35 to 90% of the current average daily intake of EPA and DHA in North America. The results indicate that FM may have a role in niche marketing of beef provided that eating quality is not compromised.     

Technical note: an algebraic method for calculating fecal output from a pulse dose of an external marker

Fecal output estimates derived from a one-compartment, Gamma-2, age-dependent model were compared with estimates derived algebraically by computing the area under the marker excretion curve for lambs given a pulse dose of ytterbium-labeled forage. Lambs were fed one of four diets (as-fed basis): 100% alfalfa hay, 100% prairie hay, 50:50 alfalfa:sorghum grain, and 50:50 prairie hay:sorghum grain. For the one-compartment model, fecal output was calculated as the dose of Yb (micrograms) divided by the initial concentration in the compartment (micrograms of Yb/gram of DM) multiplied by the age-dependent rate constant (hours-1). For the algebraic method, fecal output was calculated as the dose of Yb divided by the area under the marker excretion curve ([micrograms of Yb/gram of fecal DM].hours), both with the full complement of fecal samples and with fecal samples collected at 12-h intervals. Fecal output estimated by the three methods did not differ (P > .15) from measured fecal output (total collection). Marker retention time calculated from the one-compartment, age-dependent model was numerically greater (P > .10) than retention time calculated algebraically (sum of concentration x time divided by sum of concentrations weighted for collection interval) for lambs fed all four diets. These results suggest that the area under the marker excretion curve generated from a pulse dose of Yb-labeled forage will provide estimates of fecal output that do not differ from those calculated from a one-compartment, age-dependent model.     

Monensin effects on digestion of corn or barley high-concentrate diets

We conducted two experiments to determine the effects of monensin addition on digestion of high-concentrate diets based on corn or barley and to identify any interactions between grain source and monensin addition. A replicated in vitro experiment with a 2 x 4 factorial arrangement was used to evaluate monensin addition (0 or 72 mg/kg in vitro substrate) and grain source (corn, Gunhilde barley [GUN], Harrington barley [HAR], or Medallion barley [MED]). Triplicate tubes for each treatment were incubated for 0, 3, 6, 9, 12, 18, 24, and 30 h. Rate and extent of IVDMD were determined. Four ruminally and abomasally cannulated steers were used in a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments to test the effects of monensin addition (0 vs 270 mg x steer(-1) x d(-1)) and grain source (70% corn vs 80% Medallion barley). Diets were balanced to be isocaloric and isonitrogenous. An interaction (P < .10) was found between monensin addition and grain source for IVDMD during 3 through 9 h of incubation. Monensin increased the IVDMD of GUN and MED, but it decreased the IVDMD of HAR. Corn IVDMD was not affected by monensin addition. Steers fed Medallion barley had greater (P < .05) microbial protein synthesis, rate of in situ DM and starch disappearance, ruminal and postruminal digestion of starch, ruminal total VFA concentrations, and total tract digestion of DM, OM, and starch compared with steers fed corn. Monensin addition decreased (P < .10) ruminal digestion of feed N and ruminal proportions of acetate and butyrate and increased (P < .001) the ruminal proportion of propionate. No monensin x grain source interactions were observed for the variables measured in vivo.     

Barley varieties for finishing steers: II. Ruminal characteristics and rate, site, and extent of digestion

Four ruminally and abomasally cannulated steers were used to evaluate the effects of barely variety on rate, site, and extent of digestion of high-concentrate diets. The treatments compared were 1) corn, 2) Gunhilde barley (GUN), Harrington barley (HAR), and 4) Medallion barley (MED). Diets were balanced to be isocaloric and isonitrogenous. Ruminal OM digestion was greater (P = .04) in steers fed corn than in those fed GUN, HAR, and MED (61.9 vs average 53.7%). No differences (P > .10) were seen in ruminal starch digestion (average 92.8%) or in starch flow to the abomasum (average 199 g/d) between diets. Total tract digestion of starch was greater (P = .09) in steers fed barley than in those fed corn (average 98.6 vs 95.7%). Total and nonammonia N presented to the abomasum were greater (P < .05) for steers fed HAR and GUN than for those fed MED and corn. Microbial N flow was lowest (P = .01) in corn-fed steers, highest in steers fed GUN and HAR, and intermediate in steers fed MED. Microbial efficiency was 59% greater (P = .03) in steers fed barley than in steers consuming corn. Ruminal acetate: propionate was lower (P = .002) in steers fed corn and HAR than in those fed GUN and MED. Compared to GUN, HAR, and MED barleys, corn had a lower (P < .03) rate (-.11 vs average -.47) and extent (15 h; 70.3 vs average 98.1%) of in situ starch disappearance. Differences in digestive characteristics found between barley varieties may contribute to differences in animal performance.     

Preference for flavored wheat straw by lambs conditioned with intraruminal administrations of sodium propionate

We hypothesized that volatile fatty acids are feedback signals that condition food preferences in ruminants, and we tested two predictions based on this hypothesis: 1) low doses of propionate condition preferences for low-quality foods (Exp. 1 and 2) preferences are not caused by osmotic load (Exp. 2). In Exp. 1, lambs were offered chopped wheat straw flavored with either oregano or onion on odd days, whereas on even days flavors were switched and lambs received capsules containing sodium propionate. During four 8-d conditioning periods, the amounts of propionate delivered ranged from .7 to 1.4% of the daily DE intake (Period 1) or were fixed at .7% (Period 2) and 1% of the daily DE intake (Periods 3 and 4). After each 8-d conditioning period, lambs were offered oregano- and onion-flavored straw. Conditioning was then suspended and lambs were offered onion- and oregano-flavored straw at weekly intervals for 1 mo (extinction). Lambs preferred the flavor paired with propionate during conditioning (P < .001) and extinction (P < .07). During Exp. 2, a different group of lambs was conditioned as in Exp. 1, but sodium chloride was delivered at osmotic loads equivalent to those when propionate supplied .7% and 1% of the daily DE intake. Lambs strongly avoided the flavor paired with sodium chloride (P < .001). Thus, lambs acquired preferences for straw conditioned with doses of propionate typically considered ineffective in the regulation of food intake, and osmolalities generated by propionate did not cause, but probably attenuated, food preferences.     

Roasted soybeans, blood meal, and tallow as sources of fat and ruminally undegradable protein in the diets of lactating cows

The effect of roasted soybeans, blood meal, and tallow as sources of fat and RUP for lactating dairy cows was studied. Forty-five cows, blocked by age, calving date, and milk yield during the previous lactation, were assigned randomly to the following treatments (ingredient in the DM, RUP as a percentage of CP, and fat in the DM, respectively): 1) soybean meal (16, 35, and 3.2%), 2) whole roasted soybeans (18, 40, and 6.2%), 3) ground roasted soybeans (18, 40, and 6.2%), 4) blood meal (2.7, 40, and 3.2%), and 5) blood meal plus tallow (2.7 and 3, 40, and 6.2%). Diets were fed from wk 3 to 18 of lactation and consisted of 20% alfalfa silage, 30% corn silage, and 50% concentrate. The DMI of blood meal and whole roasted soybean diets was about 11% lower than DMI of the soybean meal diet. Milk yield (38.4 kg/d) and milk fat percentage (3.37%) were similar among diets. The roasted soybean diets resulted in the lowest milk protein percentage. Less than 2.7% blood meal might be advisable for diets fed to high yielding dairy cows to avoid reduced DMI.     

Persistence of the effects of early experience on consumption of low-quality roughage by sheep

The aim of this study was to determine the effects of experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-quality roughage) or fresh oats (Avena sativa) (high-quality roughage) on voluntary intake and nitrogen retention when sheep ate a low-quality roughage 9 mo after initial exposure. From 1 to 5 mo of age, experienced wethers (EW) grazed cured weeping lovegrass, whereas inexperienced wethers (IW) grazed fresh oats (initial exposure). Then both EW and IW were fed sorghum (Sorghum bicolor) hay for 45 d, fresh weeping lovegrass for 105 d, and finally alfalfa hay for 120 d. Nine months after completion of the initial exposure EW and IW were offered sorghum hay (low-quality roughage), and, in addition, both groups were offered sorghum with ad libitum access simultaneously to alfalfa hay at six levels of availability. Experienced wethers ingested 15% more (P < .02) sorghum than IW. When given sorghum simultaneously with alfalfa at different levels of availability, EW ingested more (P < .10) sorghum than IW when only sorghum was freely available. Nitrogen retention was negative in both groups, but it was less negative in EW than in IW per unit of metabolic weight (P < .09) and per wether (P < .04). The results show that early dietary experience can have profound and persistent effects on consumption of foods low in nutritional quality, apparently through changes in critical physiological mechanisms.     

Effects of feeding combinations of steam-flaked grain sorghum and steam-flaked, high-moisture, or dry-rolled corn on growth performance and carcass characteristics in feedlot cattle

The objective of these two feeding trials was to determine the associative effects of feeding steam-flaked grain sorghum (SFGS) in combination with steam-flaked (SFC), dry-rolled (DRC), or high-moisture (HMC) corn on growth performance and carcass characteristics in feedlot cattle. In Trial 1, 200 yearling heifers were blocked by weight, allotted to 25 pens, and fed one of five finishing diets (77% grain, 15% corn silage, and 8% supplement on a DM basis) for an average of 137 d. The grain combinations were 100:0, 75:25, 50:50, 25:75, and 0:100 SFC:SFGS, respectively. Treatment had no effect on DMI (P > .05), but ADG, gain efficiency, and final live and hot carcass weights decreased linearly (P < .05) as the proportion of SFGS increased in the diet. Carcass backfat, quality grade, and liver abscess score were not affected (P > .05) by treatment. In Trial 2, 306 yearling steers were blocked by weight, allotted to 30 pens, and fed diets that contained 74.5% grain, 10% corn silage, 7.5% soybean meal, 4% tallow, and 4% supplement (DM basis) for an average of 139 d. The grain and grain combinations were 100% DRC, HMC, SFC, or SFGS and a 67%:33% combination of SFGS: DRC or SFGS:HMC. For steers fed diets containing a single source of grain, those fed SFC gained 7% more live weight and had a 7% higher gain efficiency (P < .05) than those fed DRC or HMC. Growth performance of steers fed SFGS was intermediate. Feeding grain combinations (67% SFGS:33% HMC or DRC) resulted in a 5 to 6% positive associative effect (P < .05) for ADG and gain efficiency. Carcass characteristics were not affected (P > .05) by treatment. We concluded that there were significant benefits (positive associative effects) when SFGS was fed in combination with DRC or HMC, but the effects were smaller when SFGS was fed in combination with SFC.