Influence of forage level on response of feedlot steers to salinomycin supplementation

Two trials were conducted to evaluate the influence of forage level on the response of feedlot cattle to salinomycin. Diets containing 10, 15 and 20% forage were compared with 0 or 11 mg/kg salinomycin. In trial 1, treatment effects on feedlot performance were evaluated using 108 crossbred steers (295 kg) in a crossover design experiment. There were no salinomycin X forage level interactions (P greater than .20). Weight gain response to salinomycin supplementation averaged 5.4, 5.3 and 6.9%, respectively, for diets containing 10, 15 and 20% forage. Corresponding values for feed conversion response to salinomycin supplementation were 5.1, 3.9 and 5.9%. Averaged across forage level, salinomycin supplementation improved rate of weight gain and feed conversion by 5.9 and 5.2%, respectively (P less than .01). In trial 2, treatment effects on characteristics of ruminal and total tract digestion were evaluated in a 6 X 6 Latin-square design trial involving six crossbred steers (191 kg) with cannulae in the rumen and proximal duodenum. There were no interactions between salinomycin supplementation and forage level on characteristics of ruminal digestion (P greater than .20). Salinomycin supplementation did not influence synthesis of microbial N, ruminal digestion of organic matter, acid detergent fiber and starch, or molar proportions of acetate, propionate and butyrate (P greater than .20). Salinomycin supplementation increased passage of non-ammonia N to the small intestine (5.4%, P less than .10) and increased ruminal escape of feed N (24%, P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Low-quality roughages in high-concentrate pelleted diets for sheep: digestion and metabolism of nitrogen and energy as affected by dietary fiber concentration

Two trials were conducted to evaluate effects of, and interactions between, level and source of fiber in the diet on ruminal environment, microbial protein synthesis, nutrient digestion and flow of digesta through the gastrointestinal tract of multiple-fistulated sheep (trial 1; 4 X 4 Latin square design) and on ruminal, digestive and metabolic characteristics of early-weaned lambs (trial 2; randomized complete block design; 3 periods). All diets tested were pelleted and were formulated to contain either 39% or 25% neutral detergent fiber (NDF), with corncobs or cottonseed hulls (CSH) as the major NDF (roughage) sources. In trial 1, dry-matter (DM) and organic-matter (OM) digestibilities were not different (P greater than .05) among treatments. Digestibility of NDF was higher (P less than .05) with high-fiber. Bacterial N synthesis (g N/kg OM truly digested) was not different (P greater than .05) among treatments. Molar proportion acetate was higher (P less than .05) and molar proportion propionate lower (P less than .05) when sheep were fed high-fiber diets. In trial 2, apparent DM digestibility was higher (P less than .05) for lambs fed diets containing corncobs. Energy digestibility was higher (P less than .05) at the low-fiber level and for lambs fed diets containing corncobs. Apparent NDF digestibility by lambs was higher (P less than .05) at the high-fiber level and for lambs fed diets containing corncobs. Nitrogen retained (percentage of N intake) was higher (P less than .05) for lambs fed diets containing CSH. Ruminal pH and molar proportion acetate were higher (P less than .05) and molar proportion propionate lower (P less than .05) for lambs fed high-fiber diets. Although responses to corncob vs CSH inclusion in high-energy pelleted diets differ, both roughages are effective as fiber sources in sheep diets.     

Influence of protein degradability in range supplements on abomasal nitrogen flow, nitrogen balance and nutrient digestibility

Two metabolism trials were conducted with yearling steers fed mature native forage to measure the effect of supplemental protein degradability on selected metabolic variables. Supplements contained 40% crude protein equivalence. In Trial 1, four abomasal-cannulated steers weighing 290 to 379 kg were fed supplements containing the following N sources: (1) 15% corn, 85% urea (U); (2) 100% soybean meal (SBM); (3) 10% corn, 40% soybean meal, 50% urea (SBM-U) and (4) 14% corn, 36% blood meal, 50% urea (BM-U). Equal portions of the daily diet (2.2% of body weight) were fed every 2 h. Treatment differences were not significant for organic matter digestibility, abomasal organic matter flow, nonammonia N flow, feed N flow, bacterial N flow and efficiency of microbial protein synthesis. There was a positive (P less than .05) relationship between quantity of slowly degraded protein fed and nonammonia N flow (r = .97) or feed N flow (r = .98). Escape N was determined to be 21.5, 16.5 and 54.2% in SBM, SBM-U and BM-U supplements, respectively. In the second trial, no supplement, SBM, SBM-U and BM-U were fed in a N balance trial. Dry matter, crude protein and neutral detergent fiber digestibilities were higher (P less than .05) for steers fed supplemented diets. Acid detergent fiber digestibility was higher (P less than .05) for steers supplemented with SBM than steers fed the unsupplemented diets. Nitrogen retention was greater (P less than .05) for cattle fed SBM and BM-U than for cattle fed SBM-U or no supplement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Performance of feedlot steers fed diets containing laidlomycin propionate or monensin plus tylosin, and effects of laidlomycin propionate concentration on intake patterns and ruminal fermentation in beef steers during adaptation to a high-concentrate diet.

Two hundred eighty-eight beef steers (British x Continental x Brahman) were fed a 90% concentrate diet containing either no ionophore (control), laidlomycin propionate at either 6 or 12 mg/kg of dietary DM, or monensin plus tylosin (31 and 12 mg/kg of DM, respectively). Neither of the two levels of laidlomycin propionate nor monensin plus tylosin affected (P greater than .10) ADG or feed:gain ratio. Monensin plus tylosin reduced (P less than .01) daily DMI for the 161-d trial period compared with the other three treatments. Laidlomycin propionate at 6 mg/kg increased (P less than .05) DMI relative to the control, laidlomycin propionate at 12 mg/kg, and monensin plus tylosin diets during the 2nd wk of the trial and from d 57 to 84. Treatments did not affect carcass measurements. In a second experiment, 12 ruminally cannulated steers were fed diets containing no ionophore or laidlomycin propionate at either 6 or 12 mg/kg of DM. Samples were obtained for two consecutive days while the dietary concentrate level was 75%, after which the diet was switched abruptly to 90% concentrate, and samples were collected on several days during a 21-d period. The rate at which steers consumed their daily allotment of feed was not altered markedly by laidlomycin propionate. Likewise, laidlomycin propionate did not affect total ruminal VFA concentrations or proportions. Ruminal concentrations of D-lactate were reduced (P less than .10) by 6 but not by 12 mg/kg of laidlomycin propionate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of salinomycin supplementation on characteristics of digestion and feedlot performance of cattle

One hundred fifty large-frame British-cross calves, 75 heifers and 75 steers averaging 220 kg, were used in a 187-d growing-finishing trial to study the influence of dietary salinomycin levels of 0, 5.5, 11, 16.5 and 22 mg/kg on rate and efficiency of gain. The basal diet to which the ionophore was added was composed largely to steam processed grains, and contained 3% supplemental fat. Performance responses to salinomycin supplementation were similar for steers and heifers. Rate of gain was not influenced (P greater than .20); however, feed conversion was improved by an average of 5% at the 11- to 22-mg/kg levels of salinomycin supplementation (P less than .05). Although not necessarily mutually exclusive, this improvement in feed conversion could be accounted for as either a 5% increase in the net energy value of the diet (P less than .05) or a 10% reduction in maintenance requirement (P less than .10). Four steer calves (234 kg) with cannulae in the rumen and proximal duodenum were used in a 4 X 4 Latin-square design trial to determine the influence of salinomycin supplementation on characteristics of digestion. Four levels of supplementation (0, 55, 11 and 16.5 mg/kg) were evaluated using the same basal diet as in the performance trial. Total tract digestion of organic matter, acid detergent fiber, starch and protein was not significantly altered by salinomycin supplementation. However, ruminal digestion of organic matter was reduced 6.2% (P less than .05). Neither ruminal degradation of feed protein nor net microbial synthesis was significantly altered.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of calcium soaps of long-chain fatty acids on feedlot performance, carcass characteristics and ruminal metabolism of steers

Two trials were conducted to determine the effects of calcium soaps of long-chain fatty acids (calcium soap) on feedlot performance, diet digestibility, carcass characteristics and ruminal metabolism of steers fed diets (85% concentrate:15% corn silage) containing 0, 2, 4 or 6% calcium soap. In Trial 1, increasing calcium soap decreased (P less than .05) DM, CP and gross energy intake but increased total fatty acid intake. Feed to gain ratio tended to improve with increased calcium soap; gross energy conversion was not affected (P greater than .05) by diet. Average daily gain and hot carcass weight decreased (P less than .05) with addition of calcium soap; other carcass characteristics were not affected (P greater than .05). Apparent digestibilities of DM, N, energy and ash were not affected (P greater than .05) by calcium soap. Neutral detergent fiber digestibility increased linearly (P less than .08) with increasing calcium soap, whereas digestibility of total fatty acids was affected quadratically (P less than .05); fatty acid digestibility was similar among 0, 2 and 4% calcium soap diets but decreased for the 6% calcium soap diet. In Trial 2, increased calcium soap did not affect (P greater than .05) ruminal VFA concentrations, pH or in sacco NDF disappearance of orchardgrass following 12, 24 and 48 h of incubation. Calcium soap increased (P less than .07) ruminal concentrations of calcium soap fatty acids at 1, 2, 4 and 8 h postfeeding. Calcium soap did not improve performance of feedlot cattle fed high-concentrate diets. Further, calcium soap did not affect ruminal fermentation and did not dissociate significantly even when ruminal pH was below 6 for extended periods of time.     

Comparison of the effects of three methods of harvesting and storing alfalfa on nutrient digestibility by lambs and feedlot performance of steers

Two lamb digestion and three steer growth experiments were conducted to study the feeding value of alfalfa harvested as direct-cut silage (DCS) with grain added prior to ensiling or as low-moisture silage (LMS) or hay with grain added at feeding. In all experiments, alfalfa-grain mixtures contained approximately 50% alfalfa and 50% concentrate (dry matter [DM] basis). In Exp. 1, lambs fed DCS alone consumed less DM than lambs fed LMS or hay alone or any of the alfalfa-grain mixtures. Apparent digestibilities of DM and fiber components were higher (P less than .05) for DCS than for LMS or hay. Lambs that were fed LMS digested more (P less than .05) DM and fiber components than lambs fed hay. Addition of grain resulted in increased (P less than .05) DM digestibility and decreased (P less than .05) digestibilities of neutral detergent fiber and acid detergent fiber. In Exp. 2, growing steers (271 kg) fed DCS-grain had increased (P less than .05) weight gains compared with steers fed hay-grain. Steers fed any of the alfalfa-grain mixtures gained weight more rapidly (P less than .05) than steers fed corn silage (CS)-based diets. In a third experiment, finishing steers (283 kg) fed DCS-grain, LMS-grain, hay-grain or CS-based diets performed similarly (P greater than .05), although steers fed DCS-grain had higher (P less than .05) dressing percentages and yield grades than steers that were fed the other three diets and were fatter (P less than .05) than those fed LMS-grain or CS. In Exp. 4, lambs fed DCS-grain or LMS-grain had higher (P less than .05) apparent DM and organic matter digestibilities than lambs fed CS-based diets with similar forage:grain proportions. In Exp. 5, finishing steers (326 kg) fed DCS-grain gained similarly (P greater than .05) to steers fed LMS-grain or an 85% concentrate diet based on high-moisture corn. Steers fed CS diets had lower (P less than .05) gains and increased (P less than .05) feed per gain compared with steers fed DCS-grain, LMS-grain or high-moisture corn.     

Rumen protected fat in kline barley or corn diets for beef cattle: digestibility, physiological, and feedlot responses.

A rumen protected fat product composed of Ca salts of fatty acids (CAF) was evaluated in beef cattle diets. Dietary treatments in a metabolism trial (six steers, 251 +/- 15 kg) and Feedlot Trial 1 (15 individually fed heifers, 355 +/- 11 kg) consisted of 62.1% corn and 3.2% soybean meal (C), 32.6% corn and 33.1% Kline barley (CB), and 28.2% corn, 33.1% barley, and 4.5% CAF (CBF) on a DM basis. Apparent DM and OM digestibilities were higher (P less than .05) and NDF digestibility was lower (P less than .05) for C than for CB and CBF. Apparent ether extract digestibility was higher (P less than .01) for CBF than for CB. Retention of N was higher (P less than .05) for C than for CB and CBF. On d 42, Feedlot Trial 1 ruminal fluid acetate:propionate ratio was lower (P less than .01) for C than for CB and CBF, and the ratio was lower (P less than .01) for CB than for CBF. Treatments did not affect (P less than .10) ADG and DMI of heifers, but feed/gain was lower (P less than .05) for C than for CB and CBF, and feed/gain was higher (P less than .05) for CBF than for CB. In Feedlot Trial 2, steers and heifers were fed the C diet or a 57% corn, 21.4% peanut hull, 4.1% soybean meal, and 4.5% CAF diet (CF) on an ad libitum basis for 50 d. Ruminal fluid acetate and propionate were unaffected (P greater than .10) by dietary treatments. Cattle ADG tended to be lower (P greater than .10), DMI was lower (P less than .05), and feed/gain tended to be improved (P greater than .10) for CF compared with C. Kline barley has potential as a feed grain for cattle, but CAF may not improve beef cattle performance, especially when diets contain barley.     

Influence of limestone level in high concentrate and high roughage diets on site and extent of digestion in lambs

Two digestion and slaughter trials were conducted to evaluate the influence of limestone level on site and extent of digestion and rumen fermentation in lambs. In trial 1, 11 wether lambs (avg wt 40.7 kg) were fed 75% concentrate diets supplemented with .6, 1.5 or 3.0% limestone (.6,1.2,1.7% dietary Ca, respectively) in a completely randomized design. Dry matter intake increased linearly (P less than .10) with limestone level; therefore, other data were analyzed with dry matter intake as a covariate. Total tract organic matter digestion decreased linearly (P less than .05) with increasing limestone but dry matter and fiber digestion were not affected by limestone. Ruminal digestion of dry matter and organic matter declined linearly (P less than .05) with increasing limestone. Ruminal neutral detergent fiber (NDF) digestion was higher with the 1.5 than the .6 and 3.0% limestone diets (quadratic effect, P less than .05) but ruminal digestion of other fiber components was not affected by limestone. Ruminal volatile fatty acids were not affected by limestone level; however, rumen ammonia concentrations decreased linearly (P less than .05) with increasing limestone level. In trial 2, 12 wether lambs (avg wt 43.3 kg) were fed a 35% concentrate diet with .1, 1.5 or 3.0% limestone (.5, 1.2 and 1.6% dietary Ca, respectively) in a completely randomized design. Dry matter intake was not affected by limestone level, but digestibility of dry matter, organic matter and starch (P less than .10), energy, crude protein, acid detergent fiber (ADF) and cellulose (P less than .05) responded quadratically to limestone level, with increases at the 1.5% limestone level. Ruminal dry and organic matter (P less than .05), NDF (P less than .10), ADF (P less than .01), cellulose (P less than .05) and starch (P less than .05) digestion responded quadratically to limestone level with higher values at the 1.5% limestone level. Proportions of ruminal propionate increased linearly (P less than .01) with increasing limestone level and acetate: propionate ratio declined linearly (P less than .01) with limestone level.     

Effects of dry corn gluten feed on feedlot cattle performance and fiber digestibility

Effects of dry corn gluten feed (DCGF) on feedlot cattle performance and fiber digestibility were investigated. In Trial 1, 120 growing steers were fed corn silage-based diets containing 0, 40, 60 or 80% DCGF. Increasing levels of DCGF resulted in a curvilinear response in gain (P less than .05) and a linear increase in feed/gain (P less than .01). When the same steers subsequently were fed the same levels of DCGF in corn-based diets (Trial 2), increasing the percentage of dietary DCGF resulted in a linear decrease in gain (P less than .01) and a linear increase in feed/gain (P less than .01). In Trial 3, 46 crossbred steers were fed individually in a 2 x 2 factorial design to determine effects of 60 or 80% dietary high-moisture corn (HMC) or DCGF on feedlot cattle performance. Steers fed HMC had faster (P less than .08) and more efficient (P less than .05) gains than those fed DCGF, which had greater feed intakes (P less than .05). In Trial 4, 120 Angus crossbred steers were used to compare effects of 20 or 40% dietary HMC or DCGF on feedlot performance. Steers fed diets containing 40% HMC or DCGF had greater gains (P less than .01) and feed intakes (P less than .01) than those fed 20% diets. Steers fed HMC gained more efficiently than those fed DCGF (P less than .01). In an in situ trial, 0, 40, 60 or 80% dietary DCGF did not affect in situ DCGF DM or NDF disappearance. When DCGF was fermented in vitro in combination with corn silage, increasing the level of DCGF from 0 to 100% resulted in a linear increase (P less than .01) in 24 and 48 h NDF disappearance. These results suggest that at high dietary levels DCGF will support feedlot cattle gains that are nearly equal to those of cattle fed corn silage but somewhat less than those fed corn.     

Efficacy of laidlomycin propionate for increasing rate and efficiency of gain by feedlot cattle

One thousand twenty steers and heifers were used in six feeding trials to examine the influence of laidlomycin propionate on feedlot performance and to determine the most efficacious dietary concentrations of that ionophore. Cattle were fed diets ranging in energy content from 1.08 to 1.49 Mcal NEg/kg of DM. Laidlomycin propionate improved rate of gain and feed conversion in both steers and heifers. Improvements in performance were not evident when laidlomycin propionate was fed at only 3 mg/kg. However, both average daily gain and feed conversion were improved by laidlomycin propionate within the range of 6 to 12 mg/kg of DM (P less than .001). Feed consumption was not substantially affected by inclusion of laidlomycin propionate in the diet. Improvements in ADG and feed conversion were greater on lower-energy diets than on higher-energy diets, but both these performance characteristics were improved regardless of the type of diet fed. Average daily gain was maximized with laidlomycin propionate at 6 mg/kg, whereas improvements in feed conversion were sustained through 12 mg/kg. Carcasses of cattle fed diets containing 6 to 12 mg/kg of laidlomycin propionate weighed 7.3 kg more (P less than .001) than carcasses of cattle fed the control diets. Yield grade and quality grade were not affected by laidlomycin propionate (P greater than .05).     

The effect of salinomycin on apparent digestibility, indices of rumen fermentation and fattening and slaughter yields of cattle

The influence of salinomycin (0, 15, 30 and 60 mg per animal and day) on apparent digestibility of artificially dried grass was investigated in four experiments with five wether each. Three long term individual feeding experiments (210 to 252 days) with 72 growing bulls were carried out. The influence of various salinomycin levels (100 to 300 mg per animal and day) were investigated on parameters of rumen fermentation as well as fattening and slaughtering results. Salinomycin decreased insignificantly (P greater than 0.05) the apparent digestibility of organic matter (71.0; 70.1; 68.7 and 68.4%) and crude carbohydrates (71.8; 70.3; 69.2 and 68.5% resp.). The digestibility of other nutrients was not influenced. Supplementation of salinomycin reduced molar concentration of acetate (49 to 115) and butyrate (22 to 82) and increased propionate (110 to 199 mmoles per mol) in rumen liquid. Dry matter intake of bulls declined (0.8%, 13.5 and 24.6; 4.7% of experiments 1 to 3) when salinomycin was added. Daily weight gain (6.5 and 1.0%) and feed efficiency (6.8 and 6.3%) of bulls supplemented with salinomycin were improved in experiments 1 and 3. Significant decrease of feed intake of bulls of experiment 2 affected decline of weight gain probably as consequence of high salinomycin levels. Slaughtering results (except experiment 2) and body composition of bulls were not significantly influenced by salinomycin. Under consideration of own results and some references 10 to 20 mg per kg dry matter or 50 to 150 mg salinomycin per fattening bull and day are recommended as optimal level.     

Potassium and lasalocid effects on performance and digestion in lambs

Two trials were conducted to evaluate effects of dietary potassium (K) concentration and lasalocid (L) in lamb finishing diets. Treatments were arranged in a 2 X 2 factorial and consisted of a 65% concentrate diet with 1.1% K (C), .9% K + 21.3 mg L/kg (CL), 2.1% K (P) and 2.5% K + 20 mg L/kg (PL). In trial 1, 64 fine-wool lambs (initial wt 35.3 kg) were randomly assigned to the four treatments (two pens of four wethers and four ewes/treatment) for a 56-d feeding trial. Average daily gain was not affected by K, but was increased (P less than .10) by L (.23 vs .26 kg/d). Lasalocid tended (P less than .20) to improve feed:gain ratio (5.6 vs 6.3). A K X L interaction (P less than .06) was noted for feed intake, with values of 1.37, 1.45, 1.49 and 1.51 kg X head-1 X d-1 for the C, CL, P and PL groups, respectively. In trial 2, 16 wether lambs (four/treatment fed at 2% of body weight) were used in a site and extent of digestion and nitrogen (N) balance trial, using the same four diets as in trial 1. Site of digestion was estimated from abomasal samples taken at slaughter, with indigestible acid detergent fiber as a marker. Total tract organic matter digestibility was increased (P less than .05) with added K (80.1 vs 76.4%) and L (80 vs 76.4%). Ruminal starch digestibility was not affected by added K, but was decreased (P less than .10) by added L (71.8 vs 88.2%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Lysocellin effects on growth performance, ruminal fermentation, nutrient digestibility and nitrogen metabolism in steers fed forage diets

Studies were conducted to determine the effects of lysocellin on growth performance and metabolism of steers fed forage-based diets. Treatments in all experiments consisted of 1) control, 2) 100 mg lysocellin/d, 3) 200 mg lysocellin/d and 4) 200 mg monensin/d. In each of two 90-d performance studies, 24 Hereford steers were individually fed greenchop (fungus-free tall fescue and Coastal and Tifton-44 bermudagrass) ad libitum and .91 kg/d of a corn-trace mineral salt supplement. In Exp. 1, tall fescue was fed from d 1 to 45 and bermudagrass from d 46 to 90. Bermudagrass was offered during d 1 to 45 and tall fescue during d 46 to 90 in Exp. 2. Lysocellin improved gain (Exp. 1, P less than .01) and feed conversion (Exp. 1 and 2 combined, P less than .05), decreased total VFA concentrations (P less than .05), increased molar proportions of propionate, isobutyrate and isovalerate (P less than .01), decreased molar proportions of acetate and butyrate (P less than .01) and lowered acetate:propionate (P less than .01). Two metabolism studies involving a total of 16 Hereford steers were conducted. Steers were fed tall fescue greenchop and .91 kg/d supplement for a 34-d adjustment period followed by a 5-d total collection period. Lysocellin increased N digestibility (P less than .01) and N retention (P less than .06) but did not (P greater than .05) affect DM, NDF or ADF digestibility. Data indicate that lysocellin results in major alterations in ruminal fermentation and can increase growth performance and N retention in steers fed forage-based diets.     

The efficacy of salinomycin as a growth promotant for swine from 9 to 97 kg

Six trials involving 586 pigs initially averaging 9 kg were conducted at three locations (two trials/location) to evaluate the effects of the dietary addition of 0, 27.5, 55, 82.5 and 110 ppm of a monocarboxylic polyether antibiotic, salinomycin, on feed intake, growth rate and feed efficiency of swine fed corn-soybean meal-based diets. Over the total trial (9 to 97 kg), quadratic improvements in gain (P less than .01) and feed:gain (P less than .04) occurred with increasing level of salinomycin, but feed intake was not affected (P greater than .25). Mean improvements for all drug levels over control values for the total trial were 4.3% for daily gain (P less than .01) and 3.4% for feed:gain (P less than .01). For the total trial, rate and efficiency of gain were optimized in pigs fed the 82.5-ppm level of salinomycin with an improvement of 5.2% in daily gain and 4.8% in feed:gain over pigs fed the control diet. The absence of any significant trial X treatment interaction suggests that the nature of the response was not dependent on differences in environment, management or other factors that existed among trial locations.     

Nutritional value of quality protein maize and food corn for starter and growth pigs

Growth traits with starter and grower pigs and a digestion trial were conducted to compare the nutritional value of Quality Protein Maize (QPM), food corn and conventional feed corn. The QPM, food and feed corn contained .45, .31 and .29% lysine, respectively. The growth trials evaluated a QPM-soybean meal diet formulated on a lysine basis (.96% in starter and .7% in grower diets) and four diets arranged in a 2 (food corn vs feed corn) X 2 (low vs high soybean meal) factorial. Soybean meal was either added in the same amount as in the QPM diet or was added to provide the lysine content of the QPM diet. Performance was similar for pigs fed food corn and feed corn in both trials. The QPM diets resulted in greater performance than food and feed corn diets containing the same level of soybean meal supplementation; starter pigs were more (P less than .10) efficient and grower pigs had a higher (P less than .01) rate and efficiency of gain. However, performance of pigs fed the QPM diets was not equal to that of pigs fed isolysinic food and feed corn diets; growth rate was lower (P less than .05) in starter pigs and gain:feed was lower (P less than .05) in grower pigs. Diets in the digestion trial consisted of the corns plus 3.25% casein. Energy digestibility was similar for all diets. Ileal N and amino acid digestibilities were highest for QPM, intermediate for food corn and lowest for feed corn. In most instances, these differences were significant (P less than .05). Apparent biological value was highest (P less than .05) for QPM. These trials indicate that food corn and feed corn have similar nutritional value, and that starter and grower pigs can benefit from the higher protein quality of QPM.     

Nutritive characteristics of pearl millet grain in beef cattle diets

Two trials were conducted to compare pearl millet grain with corn and grain sorghum in cattle diets. Grain portions of diets in metabolism and feedlot experiments contained 73% corn and 6% soybean meal (C); 76.2% grain sorghum and 2.8% soybean meal (GS); and 79% pearl millet (PM). In the metabolism trial (replicated 3 x 3 latin squares; six steers), apparent digestibilities of DM and OM were higher (P less than .05) for C than for GS or PM diets. Ether extract and CP digestibilities were higher (P less than .05) for C and PM than GS. Dietary TDN was higher (P less than .05) for C compared with GS or PM diets. Fecal N was higher (P less than .05) for GS than for C or PM, urinary N was higher (P less than .05) for PM than C or GS, but retained N was similar (P greater than .05) for C, GS and PM diets. In a 90-d feedlot trial (18 individually fed heifers), a trend was observed for higher (P less than .20) ADG on C compared with PM; however, feed/gain was similar for C, GS and PM diets (8.2, 9.1 and 8.5 kg feed/kg gain, respectively). Ruminal fluid acetate:propionate ratios were lower (P less than .05) at 3.5 and 7 h postfeeding for PM compared with C or GS diets on d 83. Pearl millet grain may be used as a feed grain for beef cattle, but diets should be formulated to efficiently utilize the high quantity of protein (about 14% of DM) in this grain as a substitute for supplemental protein.     

Effect of a supply of raw or extruded rapeseeds on digestion in dairy cows.

The influence of extruded oilseeds on total tract digestibility and ruminal digestion in dairy cows was studied in three cows fed a hay-concentrate (60.5/39.5; 3.7% fatty acids in diet on DM basis) control diet (C) or the same diet supplemented with raw (R) or extruded (ER) rapeseeds (8.0% fatty acids in diet DM). The experimental design was a 3 x 3 Latin square design. Compared with diet C, diets containing rapeseed decreased ruminal OM digestibility (9.5%, P less than .10) and increased (P less than .05) the proportion of propionate in ruminal fluid VFA. Extrusion had no effect on DM and OM total tract digestibilities and increased (P less than .10) N digestion. Microbial N flow at the duodenum was calculated taking into account solid-adherent bacteria (SAB) and liquid-associated bacteria (LAB). Duodenal flows of total, SAB, and LAB of OM and N did not change with diet. Extrusion of the rapeseeds did not modify (P less than .10) the proportion of bacterial N at the duodenum and had no effect on crude fiber digestibility. This trial demonstrates that rapeseeds in hay-based diets can be fed at levels of up to 14% of the diet without adversely affecting crude fiber digestibility.     

Dietary energy density and frame size effects on composition of gain in feedlot cattle

Experiments were conducted to evaluate the effects of dietary energy density or genetic background on protein and fat gain of growing cattle. In Exp. 1, 24 Limousin steers were used in a growing-finishing trial. A 2 X 2 factorial arrangement was used with steers randomly allotted to four treatment combinations and fed the following diets: 80% concentrate, high moisture corn-corn silage diet (HI) or a corn silage diet (LO) during both the growing (GRO) and(or) the finishing (FIN) phases. Body composition for both experiments was determined by a deuterium oxide dilution technique. Empty body weight gains were greater (P less than .05) for HI during GRO, FIN and the total trial. Daily protein gains (DPG) were greater (P less than .05) for HI during GRO and FIN, while cattle receiving HI during at least FIN had the greatest (P less than .05) overall DPG. Daily fat gains (DFG) followed the pattern of DPG, being more rapid (P less than .05) for cattle fed HI during either GRO or FIN. Cattle fed the HI diet also tended to be more energetically efficient. In Exp. 2, large frame (LG) and small frame (SM) cattle were used for the evaluation of frame size effects on protein and fat deposition. Steers were individually fed an 80% concentrate, corn-based diet during the entire trial. Average daily gains and daily dry matter intake (P less than .05, P less than .01) were greater for LG, while feed efficiency was similar for both cattle types. Large cattle had greater (P less than .05) DPG than SM cattle, however, DFG were not different. Small frame steers were energetically more efficient (P less than .05), apparently due to composition of gain difference.     

Effect of protein and(or) carbohydrate fractions of dried whey on performance and nutrient digestibility of early weaned pigs

One hundred eighty 3-wk-old pigs (initial weight 4.8 kg) were utilized in a 35-d growth trial to determine the effects of the carbohydrate and(or) protein fraction of dried whey on pig performance. In addition, 30, 3-wk-old pigs (initial weight 4.9 kg) were used in two digestion trials to study the effects of the whey fraction on nutrient digestibility. Dietary treatments included a corn-soybean meal diet (control), control + 20% dried whey, control + 14.4% lactose, control + 2.1% lactalbumin, control + 14.4% lactose + 2.1% lactalbumin, and control + 8.4% whey protein concentrate. Pelleted diets containing equal lysine concentrations were fed. Lactose and lactalbumin were added at the same levels as provided by a 20% dried whey diet. Pigs fed diets containing milk products exhibited superior (P less than .05) ADG and efficiency of feed utilization and greater (P less than .05) apparent digestibilities for DM, energy and N compared with pigs fed the control diet. Including either lactose or lactalbumin in the diet for the early weaned pig resulted in similar gain, feed efficiency and nutrient digestibility. These results indicate that both the carbohydrate (lactose) and protein (lactalbumin) fractions of dried whey are important in explaining the beneficial response to dried whey elicited in the weanling pig.