Influence of tempering on the feeding value of rolled corn in finishing diets for feedlot cattle

Crossbred yearling steers (n = 125; 372 kg) were used in a 109-d finishing trial. Steers were fed an 88% concentrate diet containing 65% corn (DM basis) as 1) dry rolled corn (DRC); 2) tempered rolled corn (TRC), 43 mg surfactant (SarTemp)/kg corn; 3) TRC, 172 mg surfactant/kg corn; 4) TRC, 430 mg surfactant/kg corn; and 5) steam-flaked corn (SFC). Corn moisture was greater (3.5%, P < .01) for TRC than for DRC but less (10%, P < .05) than for SFC. Starch enzymatic reactivity was less for TRC than for either DRC (18%, P < .05) or SFC (42%, P < .01). Tempering increased the integrity of rolled corn and reduced the amount of particles less than 2 mm in diameter by 54% (P < .01). Steam flaking corn increased (P < .01) proportion (78%) of the grain having a particle size distribution of greater than 8 mm, as compared with TRC (25%) and DRC (3%). Compared with DRC, tempering enhanced (P < .10) ADG (9%), feed efficiency (5%), and dietary NE (3%). Daily weight gain was similar (P > .10) for TRC and SFC. Feed efficiency (P < .10) and dietary NE (P < .01) were greater (6%) for SFC than for TRC. There were no differences (P > .10) between DRC and TRC in ruminal and total tract digestion of OM, N, and starch, and in ruminal microbial efficiency. Ruminal digestion of OM decreased (linear effect, P < .05) and ruminal microbial efficiency increased (linear effect, P < .05) with increasing surfactant concentration. Ruminal digestion of OM and starch, and flow of nonammonia N to the small intestine were greater (31, 56, and 14%, respectively, P < .01) for SFC than for TRC. Postruminal and total tract digestion of OM, N, and starch, and dietary DE were greater (P < .01) for SFC than for TRC. We concluded that tempering corn will enhance animal performance. Increasing the concentration of surfactant used in tempering may enhance ruminal microbial efficiency and lean tissue growth.     

The feeding value of dry-rolled and steam-flaked corn in finishing diets for feedlot cattle: influence of protein supplementation

We used 80 medium-framed yearling crossbred heifers (357 kg) in a 110-d trial to evaluate the influence of dietary protein level (11 vs 14%) on the feeding value of dry-rolled (DRC) and steam-flaked corn (SFC). All diets contained 1% urea; cottonseed meal (CSM) was the source of supplemental undegradable intake protein (UIP). Steam flaking corn reduced DMI (9%, P < .10) and increased (P < .01) feed efficiency (14%), dietary NEm (13%), and NEg (15%). Steam flaking increased the NEm by 17% and NEg by 19%. Supplemental CSM decreased (P < .10) feed efficiency (7%) and dietary NEm (4%) and NEg (6%). There were no treatment effects (P > .10) on carcass characteristics. Steam flaking corn increased (P < .05) fecal pH and reduced (P < .01) fecal starch. Supplemental CSM increased (P < .01) fecal pH and reduced (P < .01) fecal starch. Four Holstein steers (413 kg) were used in a 4 x 4 Latin square experiment to evaluate treatment effects on digestive function. Steam flaking corn increased (P < .05) flow of nonammonia N (11%, P < .05) and microbial N (15%, P < .01) to the duodenum. Supplemental CSM increased the flow of microbial N (6%, P < .01), feed N (21%, P < .10), and nonammonia N (12%, P < .05) to the duodenum. The UIP value of CSM was 28% for the DRC diet and 52% for the SFC diet. Steam flaking corn increased (P < .01) ruminal starch digestion (26%) and total tract digestibility of OM (17%), N (15%), starch (19%), and GE (17%). Steam flaking increased the DE value of corn by 21%. Supplemental CSM did not influence (P > .10) postruminal or total tract starch digestion. Supplemental CSM decreased (7%, P < .10) the DE value of the diet. We conclude that increasing the postruminal protein supply of a corn-based finishing diet beyond that provided by urea supplementation, alone, will not enhance starch digestion or the energy value of the diet.     

Effect of energy source and escape protein on receiving and finishing performance and health of calves

Two receiving and two finishing trials evaluated energy source and escape protein supplementation for calves. In receiving Trial 1, 398 calves (257 +/- 24 kg BW) were used in a 2 x 2 factorial arrangement of treatments. Energy sources were dry-rolled corn (DRC) and wet corn gluten feed (WCGF); each was fed without or with supplemental escape protein (EP). Calves fed WCGF gained slower (P < .05) and consumed less DM (P < .01) than calves fed DRC. Feed efficiency improved (P < .10) with EP supplementation. In finishing Trial 1, 240 calves (305 +/- 21 kg BW) were used. The arrangement of treatments was the same as in receiving Trial 1. Calves fed DRC/WCGF tended (P = .15) to be more efficient and consumed less DM (P < .05) than calves fed DRC. In receiving Trial 2, 315 calves (252 +/- 23 kg BW) were fed diets similar to those fed in receiving Trial 1. Calves fed WCGF consumed less DM (P < .01), gained similarly (P > .15), and were more efficient (P < .10) than calves fed DRC. In finishing Trial 2, 320 calves (298 +/- 23 kg BW) were fed diets containing DRC, DRC/WCGF, high-moisture corn (HMC), HMC/WCGF, and DRC/HMC; each was fed without or with supplemental EP. An energy source x protein supplement interaction was detected for gain (P < .05) and efficiency (P < .01). Results suggest that WCGF has a NEg greater than DRC in receiving diets and a NEg similar to that of DRC but lower than that of HMC in finishing diets.     

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.     

Performance, digestion, and mastication efficiency of Holstein steers fed whole or processed corn in limit- or full-fed growing-finishing systems

We conducted two trials to examine the effects of restricted vs full feeding and of grain processing method on feedlot performance, digestion, and mastication efficiency by Holstein steers in different growing-finishing systems. In Trial 1, 272 Holstein steers (177 +/- 9.98 kg) were blocked by weight and assigned to growing phase diets based on corn silage (SIL), steam-flaked corn that was either limit-fed (SFLF) or full-fed (SFFF), or whole corn that was limit-fed (WCLF) or full-fed (WCFF). Limit-fed steers were fed at levels predicted to allow daily gain of 1 kg/d. On d 112, all steers were switched to WCFF or SFFF diets until the mean BW of each treatment group was 545 kg. Overall, steers fed WCLF and SFLF during the growing phase and finished on SF were 8.1 and 6.6% more efficient at converting dietary ME to gain (P = .02 and .04, respectively) than steers in the SFFF group. In Trial 2, three ruminally and duodenally cannulated Holstein steers were fed whole (WC) and rolled corn (RC) diets at FF and LF intake in an incomplete replicated 2 x 2 switchback design. Ad libitum access to feed resulted in higher (P = .02) ruminal starch digestibility than did limit-feeding, and calves had higher total tract DM (P = .05) and starch (P = .03) digestion at the heavier BW. Limit-feeding whole corn resulted in increased particle size of masticate (P = .06) compared with full-feeding whole corn. Because of apparent differences in mastication efficiency between limit-fed and full-fed calves, grain processing method during periods of restriction and compensatory growth may be important considerations for managing growth in systems that incorporate limit-feeding.     

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.     

Effect of dietary corn starch intake on ruminal, small intestinal and large intestinal starch digestion in cattle

In Exp. 1, 24 yearling Holstein steers averaging 340 kg were fed either an alfalfa hay diet at a maintenance level of metabolizable energy (ME) intake or corn silage-corn diets at one, two or three times maintenance ME intake. After a 42-day adjustment period, steers were fed individually, and digestibilities of total alpha-glucosides, starch oligosaccharides and glucose were determined at 2-week intervals, with chromic oxide used as an indicator. Steers fed the alfalfa hay diet had higher (P less than .05) total tract digestibilities of total alpha-glucosides and starch than steers fed the corn diets. Fecal starch (percentage of dry matter) in steers fed the corn diets increased (P less than .05) from approximately 11 to 31% as level of ME intake increased from one to three times maintenance. Starch digestibilities for the corn diets fed at one, two and three times maintenance were 81.4, 76.4 and 76.0%, respectively. However, these trends toward reduced starch digestibilities were not significant. There appeared to be no apparent adaption of alpha-glucoside digestibility in the total digestive tract among steers fed different levels of corn over the intervals observed. In Exp. 2, four Holstein steers (350 KH) were each fitted with duodenal and ileal reentrant cannulas and fed either a low or a high level of corn. Alpha-glucoside intakes for animals given the low and high levels of cord averaged 1.7 and 3.2 kg, respectively. Steers fed the high level of corn digested more (p less than .05) alpha-glucoside in the total tract (2.9 vs 1.6 kg), reticulo-rumen (2.3 vs 1.2 kg) and large intestine level of corn. Steers fed the high level of corn also digested more corn in the small intestine (.415 vs .221 kg) than steers fed the lower level; however, differences were not significant. Although there were trends toward lower partial digestion coefficients (expressed as a percentage of alpha-glucoside presented to that segment) in the total tract, reticulo-rumen and small intestine for steers fed the high corn diet, the magnitude of the differences was not significant.     

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.     

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.     

Female pelvic floor: endovaginal MR imaging of normal anatomy

Five types of processed corn were compared to determine the effects of processing on lactational performance and nutrient digestibilities in dairy cows. Forty lactating Holstein cows averaging 160 +/- 60 d in milk were randomly divided into five groups on the basis of pretreatment milk yields and were fed diets containing 40% corn grain for 56 d. Treatments were 1) finely ground corn, 2) coarsely ground corn, 3) steam-flaked corn at a low density, 4) steam-flaked corn at a medium density, and 5) steam-rolled corn. Cows fed the diet containing steam-flaked corn at a medium density had a higher milk yield (37.1 kg/d) than did cows fed the diets containing coarsely ground corn, steam-flaked corn at a low density, or steam-rolled corn; cows fed the diet containing finely ground corn had an intermediate milk yield (35.5 kg/d). Efficiency of feed utilization was greater, and dry matter intake was lower, for cows fed the diet containing finely ground corn than for cows fed the other diets. The fat content of milk was higher for cows fed the diets containing coarsely ground corn and steam-rolled corn than for cows fed the diet containing steam-flaked corn at a medium density. Milk protein and SNF contents and yields of protein, lactose, and SNF did not differ among diets. Apparent starch digestibilities in the total digestive tract were lower for diets containing coarsely ground corn (87.4%) and steam-rolled corn (91.3%) than for the other diets (X = 96.3%). Milk yield was highest for cows fed the diet containing steam-flaked corn with a medium density. Fine grinding resulted in the greatest efficiency of feed utilization.     

Interaction of feed intake level on comparative ruminal and total tract digestion of dry-rolled and steam-flaked corn

Four Holstein steers (208 kg) with "T" cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square design experiment to evaluate the interaction of feed intake level on comparative ruminal and total tract digestion of dry-rolled and steam-flaked corn. The basal diet contained (DM basis) 6% alfalfa hay, 6% sudangrass hay, 75% corn, 2% yellow grease, 5% cottonseed meal, 3% cane molasses, and 3% supplement. The corn portion of the diet was provided as either dry-rolled (density = .54 kg/L) or steam-flaked (density = .36 kg/L). Dry matter intake was restricted to allow for .64 vs 1.28 kg/d of weight gain (1.6 vs 2.4% of BW). Ruminal digestibility of OM, starch, and feed N were not affected (P > .10) by DMI. Postruminal digestion of OM and N and total tract digestibility of OM and DE decreased (P < .05) as DMI was increased. Total tract starch digestibility was not influenced (P > .10) by DMI. Steam flaking corn increased (P < .05) ruminal digestibility of OM and starch and postruminal and total tract digestibility of OM, starch, N, DE, and ME. Increasing DMI and steam flaking decreased (P < .05) ruminal pH and molar proportion of acetate. It is concluded that corn processing is the primary factor influencing site and extent of starch digestion. Decreasing DMI increases DE value of the diet; however, ME value is not affected because of increased energy loss as methane.     

Effect of steam-flaked or steam-rolled corn with or without Aspergillus oryzae in the diet on performance of dairy cows fed during hot weather

The objective of this study was to determine the effects of steam-rolled versus steam-flaked corn in the diet with or without the addition of a culture of Aspergillus oryzae on the performance of high producing dairy cows during hot summer weather. Thirty-two Holstein cows averaging 92 (+/- 60) d in milk were fed a pretreatment diet for 21 d followed by a 70-d experimental period in a completely randomized block design with a 2 x 2 factorial arrangement of treatments. Diets were 1) steam-flaked corn plus 3 g/d of A. oryzae, 2) steam-flaked corn, 3) steam-rolled corn plus 3 g/d of A. oryzae, and 4) steam-rolled corn. Intake was not affected significantly by grain processing or addition of A. oryzae. Compared with effects from steam-rolled corn in the diet, steam-flaked corn increased milk production; percentage of milk protein; yields of milk protein, lactose, and SNF; and the efficiency of conversion of dry matter to fat-corrected milk. Addition of A. oryzae tended to increase protein percentage and increased the percentage of SNF. Changes in body weight and body condition score tended to be higher, and somatic cell count tended to be lower, for cows fed the flaked corn than for cows fed the rolled corn. No interactions were significant. Treatments did not affect rectal temperatures or respiration rates; however, high mean values measured at 1400 h once weekly indicated thermal stress. These data show improved milk production from cows fed steam-flaked corn but not from those fed diets supplemented with A. oryzae.     

The effects of roasting temperature applied to whole soybeans on site of digestion by steers: II. Protein and amino acid digestion

A 4 x 5 Youden square design was used to determine the effect of roasting temperature of whole soybeans on escape of CP from the rumen and disappearance of N from the small intestine in steers. Four steers (average BW 373 kg +/- 30.7) cannulated at the rumen, duodenum, and ileum were fed each of five diets (1.8% of BW) over five periods. The basal diet contained corn silage (50% of diet DM), alfalfa hay (24%), corn-urea premix (6%), corn starch grits (16.6%), and soybean oil (3.4%). Soybeans (16% of diet DM), either raw or heated to an exit temperature of 141, 149, or 157 degrees C in a commercial roaster, replaced the soybean oil and most of the corn starch grits in the soybean-containing diets. Ruminal ammonia N was lower (P < .05) for the basal diet than for the soybean-containing diets. Roasting temperature of whole soybeans had no significant impact on ruminal ammonia N. Total N reaching the duodenum was greater (P < .05) for steers fed the soybean diets than for steers fed the basal diet. Non-bacterial N (dietary N) at the duodenum was increased (P < .05) by feeding soybeans. Soybean N reaching the duodenum decreased with increased roasting temperature. Increased roasting temperature of whole soybeans seemed to make the soybeans more brittle, subsequently increasing degradation of CP in the rumen. However, disappearance of soybean N in the small intestine, as a proportion of the soybean N entering the small intestine, increased with increased roasting temperature. Apparent total tract N digestibility was increased (P < .05) by feeding soybeans. Flow to the duodenum and small intestinal digestibility of total, essential, and nonessential amino acids increased (P < .05) when soybeans were fed and when roasted vs raw soybeans were fed. Under normal roasting conditions, it seemed that little potential for heat damage to the soybean protein existed. Instead, undesirable effects of heating on handling characteristics of the soybeans were reached before the point at which loss of nutritive value occurred. Feeding steers diets containing roasted whole soybeans increased the N and amino acids available to steers over steers fed diets containing raw soybeans due to increased ruminal soybean nitrogen escape and increased small intestinal digestibility.     

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.     

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)     

Effects of supplemental protein source on intraruminal fermentation, protein degradation, and amino acid absorption

Cannulated steers were used to determine the effects of supplemental soybean meal, heated soybean meal, fish meal, and a combination of fish meal, heated soybean meal, and corn gluten meal on intraruminal protein degradation and absorption of AA from the small intestine. Organic matter digestion in the reticulo-rumen was greater in steers fed diets supplemented with soybean meal, but whole tract digestibility was not affected by protein source. Total and bacterial CP flows to the abomasum were lower in steers fed diets supplemented with fish meal than in steers fed diets supplemented with heated soybean meal or the combination supplement. Dietary CP flow was 33.5% higher in steers fed diets supplemented with heated soybean meal than in steers fed diets supplemented with soybean meal, fish meal, or the combination supplement. Less essential and nonessential AA flowed to the abomasum and were absorbed from the small intestine of steers receiving diets supplemented with soybean meal. Digestibility of small intestine AA was 21.9% lower in steers receiving the soybean meal treatment. Abomasal flows of Met and Thr and absorption of Lys, Met, and Thr were increased in steers fed diets containing heated soybean meal, fish meal, and the combination supplement. These results suggest that the supply of AA deficient in microbial CP (Lys, Met, and Thr) can be increased and that absorbed AA balance can be changed markedly by selection of rumen escape protein supplements.     

Growth and subsequent feedlot performance of estradiol-implanted vs nonimplanted steers grazing fall-accumulated endophyte-infested or low-endophyte tall fescue

A growing-finishing study using Angus steer calves was conducted in three phases: 1) grazing stockpiled 'Kentucky-31' tall fescue (Festuca arundinacea Schreb.) with high (65%; HE KY-31) and low (0%; LE KY-31) infestation rates of Acremonium coenophialum Morgan-Jones and Gams and 'Kenhy' and 'Johnstone' tall fescue with low (< 1%) infestation rate of Acremonium coenophialum from October 24 to December 19; 2) drylot feeding of Johnstone and HE KY-31 haylage (December 19 to April 10); and 3) feedlot finishing on a common high-concentrate diet (April 11 to August 1). In Phase 1, ADG was greatest (P < .05) for Kenhy, intermediate for Johnstone and LE KY-31, and lowest (P < .05) for HE KY-31. Implantation with estradiol 17-beta increased ADG (P < .01) by 23, 27, 7, and 2% for steers grazing Johnstone, HE KY-31, LE KY-31, and Kenhy, respectively. Dry matter digestibility and DMI of stockpiled Johnstone and HE KY-31 were not different (P > .10). During Phase 2, steers consuming Johnstone haylage had greater (P < .01) DMI, ADG, and gain:feed ratio (G:F) than steers consuming HE KY-31 haylage. During Phase 3, steers previously consuming Johnstone had greater DMI (P < .10); however, steers previously fed HE KY-31 had greater ADG (P < .05) and G:F (P < .01). By the end of the study, steer body weights were not different (P > .10) between treatments. These data indicate that growth-decreasing effects of endophyte-infested fescue were evident at hypothermal-ambient temperatures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Alfalfa and escape protein supplements for grazed corn residues

Two calf corn-residue grazing trials were conducted to evaluate the effect of supplementing with two alfalfa hays (Medicago sativa), varying in their amount of CP and ADF, with and without escape protein (EP). In Trial 1, heifers (204 kg) grazed (1.36 heifers/ha) non-irrigated fields for 92 d. No difference (P > .05) in ADG was found when medium-protein (16.3% CP) and high-protein (18.0% CP) alfalfa hays were provided at 2.7 kg of DM.heifer-1.d-1. In Trial 2, 60 steers (257 kg) were supplemented individually with medium-protein (17.6% CP) alfalfa hay, 1.86 (MPL) and 2.27 kg DM (MPH), and one level of high-protein (18.7% CP) alfalfa hay, 1.86 kg DM (HPL). In a 2 x 3 factorial arrangement of treatments, steers were fed with or without EP (113 g.steer-1.d-1 from blood meal and corn gluten meal). Steers grazed a non-irrigated corn residue field (2.58 steers/ha) for 57 d and were watered and individually supplemented overnight. Diet quality and composition was estimated by collecting extrusa samples twice each week using four esophageally fistulated steers. No effects of alfalfa protein content or level (P > .05) were reflected in gain: 357, 309, and 326 g.steer-1.d-1 for steers receiving MPL, MPH, or HPL alfalfa treatments, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Free amino acid supplementation to steers: effects on ruminal fermentation and performance

Three studies were conducted to evaluate amino acid utilization by cattle. In Exp. 1, five steers (580 kg) were fed 86% rolled corn diets with mixtures of amino acids containing up to 6 g/d DL-Met, 24 g/d L-Lys, 6 g/d L-Thr, and 3 g/d L-Trp. Treatments had little effect on ruminal fermentation, diet digestibility, N flow to the duodenum, or microbial efficiency. Ruminal concentrations of Met and Lys increased linearly (P < .05) with amino acid supplementation, whereas Thr responded quadratically, and Trp was not altered. In Exp. 2, four steers (414 kg) were used to measure effects of dietary monensin or laidlomycin propionate in high-grain diets supplemented with amino acids. Ionophores had no significant effect on ruminal fermentation or outflows of amino acids from the rumen. In Exp. 3, 100 steers (287 kg initial BW) were fed diets containing 1% of a nonprotein N source. Treatments were 1) no supplemental N (UREA), 2) UREA plus soybean meal (SBM), 3) UREA plus 2 g/d DL-Met, 8 g/d L-Lys, 2 g/d L-Thr, and 1 g/d L-Trp, or 4) UREA plus 4 g/d DL-Met, 16 g/d L-Lys, 4 g/d L-Thr, and 2 g/d L-Trp. During the growing period (diets based on whole-plant milo silage), gains were higher for SBM-supplemented steers than for UREA steers and intermediate for steers supplemented with amino acids. Few significant differences in performance were observed among treatments during the finishing phase (diets based on dry-rolled corn) or for the entire experiment, but cattle fed SBM or amino acids tended to be fatter and have better marbling scores and quality grades. Amino acids did not greatly alter ruminal fermentation or cattle performance.