Effects of supplementing prairie hay with corn and soybean meal on intake, digestion, and ruminal measurements by beef steers

Prairie hay supplemented with various amounts of corn and soybean meal was fed to steers in two experiments. Effects of supplementation on hay OM intake, digestion, and ruminal fermentation and kinetics were measured. A preliminary study was conducted to attain accurate values for OM intake and digestibility of prairie hay to be used in ration formulation using the NRC (1996) level 1 model. Ten steers (284 +/- 9 kg) given ad libitum access to chopped prairie hay (75% NDF, 6% CP) were supplemented with dry-rolled corn (0.75% of BW/d) plus soybean meal (0.25% of BW/d). Hay OM intake was 1.85% of BW and hay OM digestibility was 48%. Based on results from the preliminary study, eight ruminally cannulated beef steers (317 +/- 25 kg) received a sequence of eight different supplementation combinations (2 x 4 factorial arrangement of treatments). These supplements consisted of dry-rolled corn at either 0 or 0.75% of BW (DM basis) daily combined with one of four amounts of added soybean meal to provide between 0 and 1.3 g of degradable intake protein (DIP)/kg of BW. After supplements had been fed for 10 d, feces were collected for 4 d. Intake of hay and total OM increased quadratically (P < 0.01) in response to added DIP with or without supplemental corn. Hay OM digestibility increased quadratically (P = 0.03) as DIP was added when corn was fed in the supplement. Intake of digestible OM was greater (P < 0.01) with than without corn supplementation. Increasing DIP increased (P < 0.01) digestible OM intake regardless of whether corn was fed. Inadequate ruminally degraded protein in grain-based supplements decreased forage intake, digestibility, and energy intake of cattle fed low-quality prairie hay. Providing adequate supplemental DIP to meet total diet DIP needs seemed to overcome negative associative effects typically found from supplementing low-quality forages with large quantities of low-protein, high-starch feeds.     

The effects of degradable and undegradable intake protein on the performance of lactating first-calf heifers

Two 60-d experiments were conducted to evaluate the effects of supplementing degradable (DIP) and(or) undegradable (UIP) intake protein on the performance of lactating first-calf heifers. Diets were formulated to meet the requirements for either DIP, metabolizable protein (MP), or both when diets contained low-quality grass hay and an efficiency of microbial protein synthesis estimate of 10%. In Exp. 1, 32 individually fed first-calf heifers (avg 395 kg) were allotted to a 2 x 2 factorial arrangement of treatments (main effects of DIP, MP, and DIP x MP interaction) 1 d after calving. Cows consumed a basal diet of chopped crested wheat grass hay (4.3% CP, 67% DIP) ad libitum. Supplemental DIP and UIP were supplied by varying the ratios of soybean meal (75% DIP) and a heat-treated, protected soybean meal (70% UIP). Cow weight gain was better (P < 0.01) when adequate DIP was supplied than when DIP was deficient. However, calf weight gain was not increased by supplementing the cow with DIP. Supplemental UIP did not (P > 0.40) improve cow or calf weight gain. Blood urea N levels were higher (P < 0.01) for cows receiving supplemental DIP and UIP. However, milk production estimates were similar among treatments, as were digestibilities of OM and ADF. Nitrogen digestibility was greater when supplemental DIP was fed, but providing additional UIP did not (P = 0.15) change N digestibilities. Experiment 2 evaluated similar supplements using the same experimental design to determine changes in cow and calf weight gain, body condition score, and pregnancy rate. Seventy-two first-calf heifers (avg 441 kg) were allotted to supplement treatments 1 d after calving and were fed grass hay (5% CP, 53% DIP, 10% microbial efficiency) for ad libitum consumption for 60 d. Supplements were individually fed three times/week. Varying the ratios of soybean meal, heat-treated soybean meal, and corn gluten meal provided additional DIP and UIP. Unlike in Exp. 1, supplemental UIP improved (P < 0.05) cow weight gain. Calves from dams supplemented with DIP gained 5 kg more weight after 60 d than calves from dams deficient in DIP. Pregnancy rates in the fall were similar (P = 0.90) among treatments. These data suggest that DIP was more limiting in Exp. 1 than was UIP. Supplementing UIP in Exp. 2 improved cow weight gains but did not improve calf gains. Data suggest that the efficiency of microbial protein synthesis for this forage-based diet was probably less than 10%.     

Effect of supplementation frequency and supplemental urea level on dormant tallgrass-prairie hay intake and digestion by beef steers and prepartum performance of beef cows grazing dormant tallgrass-prairie

Effect of supplementation frequency and supplemental urea level on forage use (Exp. 1) and performance (Exp. 2 and 3) of beef cattle consuming low-quality tallgrass-prairie were evaluated. For Exp. 1 and 2, a 2 x 2 factorial treatment structure was used, such that two supplements (30% CP) containing 0 or 30% of supplemental degradable intake protein (DIP) from urea were fed daily or on alternate days. In Exp. 1 and 2, supplement was fed at 0.41% BW daily or at 0.83% BW (DM basis) on alternate days. For Exp. 3, a 2 x 4 factorial treatment structure was used, such that four supplements (40% CP) containing 0, 15, 30, or 45% of supplemental DIP from urea were fed daily or 3 d/wk. Supplements were group-fed at 0.32% BW daily or at 0.73% BW (DM basis) 3 d/wk. In Exp. 1, 16 Angus x Hereford steers (initial BW = 252 kg) were blocked by BW and assigned to treatment. Urea level x supplementation frequency interactions were not evident for forage intake, digestion, or rate of passage. Forage OM intake (OMI) and total digestible OMI (TDOMI) were not significantly affected by treatment. Total-tract digestion of OM (P = 0.03) and NDF (P = 0.06) were greater for steers supplemented daily. In Exp. 2, 48 Angus x Hereford cows (initial BW = 490 kg) grazing winter tallgrass prairie were used. Significant frequency x urea interactions were not evident for BW and body condition (BC) change; similarly, the main effects were not substantive for these variables. In Exp. 3, 160 Angus x Hereford cows (initial BW = 525 kg) grazing dormant, tallgrass prairie were used. Supplement refusal occurred for cows fed the highest urea levels, particularly for cows fed the supplement with 45% of the DIP from urea 3 d/wk, and supplement refusal increased closer to calving. A frequency x urea interaction (P = 0.02) was observed for prepartum BW changes. As supplemental urea level increased, prepartum BW loss increased quadratically (P = 0.02); however, a greater magnitude of loss occurred when feeding supplements containing > or = 30% of DIP from urea 3 d/ wk. Cumulative BC change followed a similar trend. In conclusion, moderate protein (< or = 30% CP) supplements with < or = 30% of supplemental DIP from urea can be fed on alternate days without a substantive performance penalty. However, infrequent feeding of higher protein (> 30% CP) supplements with significant urea levels (> 15% of DIP from urea) may result in decreased performance compared with lower urea levels.     

Effects of corn condensed distillers solubles supplementation on ruminal fermentation, digestion, and in situ disappearance in steers consuming low-quality hay

Two metabolism (4 x 4 Latin square design) experiments were conducted to evaluate the effects of corn condensed distillers solubles (CCDS) supplementation on intake, ruminal fermentation, site of digestion, and the in situ disappearance rate of forage in beef steers fed low-quality switchgrass hay (Panicum virgatum L.). Experimental periods for both trials consisted of a 9-d diet adaptation and 5 d of collection. In Exp. 1, 4 ruminally and duodenally cannulated steers (561 +/- 53 kg of initial BW) were fed low-quality switchgrass hay (5.1% CP, 40.3% ADF, 7.5% ash; DM basis) and supplemented with CCDS (15.4% CP, 4.2% fat; DM basis). Treatments included 1) no CCDS; 2) 5% CCDS; 3) 10% CCDS; and 4) 15% CCDS (DM basis), which was offered separately from the hay. In Exp. 2, 4 ruminally and duodenally cannulated steers (266.7 +/- 9.5 kg of initial BW) were assigned to treatments similar to Exp. 1, except forage (Panicum virgatum L.; 3.3% CP, 42.5% ADF, 5.9% ash; DM basis) and CCDS (21.6% CP, 17.4% fat; DM basis) were fed as a mixed ration, using a forage mixer to blend the CCDS with the hay. In Exp. 1, ruminal, postruminal, and total tract OM digestibilities were not affected (P = 0.21 to 0.59) by treatment. Crude protein intake and total tract CP digestibility increased linearly with increasing CCDS (P = 0.001 and 0.009, respectively). Microbial CP synthesis tended (P = 0.11) to increase linearly with increasing CCDS, whereas microbial efficiency was not different (P = 0.38). Supplementation of CCDS to low-quality hay-based diets tended to increase total DM and OM intakes (P = 0.11 and 0.13, respectively) without affecting hay DMI (P = 0.70). In Exp. 2, ruminal OM digestion increased linearly (P = 0.003) with increasing CCDS, whereas postruminal and total tract OM digestibilities were not affected (P > or = 0.37) by treatment. Crude protein intake, total tract CP digestibility, and microbial CP synthesis increased (P < or = 0.06) with increasing level of CCDS supplementation, whereas microbial efficiency did not change (P = 0.43). Ruminal digestion of ADF and NDF increased (P = 0.02 and 0.008, respectively) with CCDS supplementation. Based on this data, CCDS used in Exp. 2 was 86.7% rumen degradable protein. The results indicate that CCDS supplementation improves nutrient availability and use of low-quality forages.     

Source and level of energy supplementation for yearling cattle fed ammoniated hay

Brahman x British crossbred steers were used in growth and digestion trials to evaluate the response of source (corn, sugar cane molasses, or soybean hulls) and feeding rate (0, 1.4, or 2.8 kg DM per steer daily in the growth trials; 0, 15, or 30% of the ration DM in the digestion trial) of energy supplementation in cattle fed ammoniated (4% of forage DM) stargrass (Cynodon nlemfuensis Vanderyst var. nlemfuensis) hay. Cattle on all treatments were fed 0.5 kg cottonseed meal daily. In the growth trials, steers grazed dormant bahiagrass (Paspalum notatum) pasture. Increasing the levels of supplementation decreased hay intake but increased total dietary intake for all diets (P < 0.07). Daily gain and feed efficiency of steers were improved (P < 0.03) with supplementation. Steers supplemented with corn or soybean hulls at 2.8 kg DM/d had a higher ADG (0.92 kg) and gain/feed (0.103) than steers supplemented with molasses (0.78 kg, 0.08, respectively) at the same level. Seven crossbred steers (200 kg) were used in a five-period digestion trial to evaluate apparent OM, NDF, ADF, and hemicellulose digestibility. Apparent OM digestibility of all diets increased linearly (P = 0.02) as the level of supplementation increased. Apparent NDF and ADF digestibility decreased (P < 0.03) as the level of supplementation with corn or molasses increased, whereas increasing the level of soybean hulls in the diet increased (P < 0.06) apparent NDF and ADF digestibility. Four ruminally fistulated crossbred steers (472 kg) were used in a 4 x 4 latin square design to investigate ruminal characteristics with energy supplementation at 30% of ration DM. Ruminal pH in steers supplemented with soybean hulls or corn declined after feeding. Ruminal pH decreased more rapidly with corn supplementation and remained below 6.2 for a longer period of time than with the other diets. Ruminal pH did not change within 24 h after feeding for steers fed the control or molasses diets. No change in total VFA concentration was observed in steers fed molasses or corn. Total ruminal VFA concentration in steers supplemented with soybean hulls increased initially after feeding and then declined within 24 h after feeding. Soybean hulls produced fewer negative associative effects than corn when fed with ammoniated stargrass hay at 2.8 kg DM/d. The reduced gain/feed of steers supplemented with molasses compared to soybean hulls or corn indicates that molasses was not utilized as efficiently as the other energy sources.     

Rice mill feed as a replacement for broiler litter in diets for growing beef cattle

The efficacy of replacing broiler litter with rice mill feed was evaluated in four experiments. In Exp. 1, 40 predominantly Angus steers (initial BW = 277+/-18.2 kg) were fed four dietary treatments for 112 d (five steers per pen; two pens per diet). Dietary treatments (DM basis) were as follows: 1) 47% broiler litter:53% corn; 2) 60% rice mill feed:40% corn; 3) 50% rice mill feed:50% corn; and 4) 40% rice mill feed:60% corn. All diets, along with bermudagrass hay, were fed free choice. Daily gains were faster (P < 0.10) for the 50:50 and 40:60 diets (1.26 and 1.30 kg/d, respectively) than for the broiler litter diet (0.89 kg/d). Daily DMI was less (P < 0.10) by steers consuming rice mill feed-based diets than by those consuming broiler litter-based diets. In Exp. 2, 16 Angus x Charolais steers (initial BW = 277+/-22.7 kg) were fed the same four diets used in Exp. 1 while housed in individual metabolism stalls for determination of nutrient digestibility. Daily DMI was not different (P > 0.10) among diets. Nutrient digestibilities did not differ among diets (P > 0.10). In Exp. 3, 40 Continental cross steers (initial BW = 257+/-21.3 kg) were fed one of four dietary treatments for 112 d (five steers per pen; two pens per diet). On a DM basis, diets were as follows: 1) 47% broiler litter:53% soyhulls; 2) 70% rice mill feed:30% soyhulls; 3) 60% rice mill feed:40% soyhulls; and 4) 50% rice mill feed:50% soyhulls. All diets, along with bermudagrass hay, were fed free choice. Daily gains were less (P < 0.05) for the broiler litter diet than for the 60:40 and 50:50 diets (1.05, 1.16, and 1.28 kg/d, respectively), and steers fed the broiler litter diet consumed less DM than did steers fed the varying rice mill feed-based diets (P < 0.10). In Exp. 4, 16 Angus x Charolais steers (initial BW = 292+/-21.1 kg) were fed the same four diets as in Exp. 3 while housed in individual metabolism stalls for determination of nutrient digestibility. Daily DMI was less (P < 0.01) for the broiler litter diet (5.0 kg/d) than for the 70:30, 60:40, and 50:50 diets (7.8, 7.9, and 7.9 kg/ d, respectively). Digestibilities for DM, OM, and ADF did not differ (P > 0.10) among treatments; however, CP digestibility was greatest (P < 0.10) for the 60:40 diet, and NDF digestibility was least (P < 0.10) for the 70:30 diet. Rice mill feed can be used to replace broiler litter to formulate low-cost diets for stocker calves. Soyhulls and corn can be blended with rice mill feed to produce acceptable backgrounding diets for growing beef calves.     

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.     

Effects of supplemental protein type on intake, nitrogen balance, and site, and extent of digestion in whiteface wethers consuming low-quality grass hay

Two experiments were conducted to determine the effects of supplementing ruminally degradable intake protein (DIP) or ruminally undegradable intake protein (UIP) on N balance (Exp. 1; n = 6 wethers; initial BW = 48.7 +/- 4.6 kg) and site and extent of digestion (Exp. 2; n = 5 wethers; initial BW = 36.9 +/- 3.1 kg) in whiteface wethers consuming (as-fed basis) 69% blue grama and 31% love grass hay (mixture = 7.5% CP, 73.0% NDF, 36.0% ADF [DM basis]). Treatments were 1) no supplement (Control), 2) a supplement (219 g/d, as-fed basis) low in UIP (70 g/d of CP; 24.8 g/d of UIP), and 3) a supplement (219 g/d, as-fed basis) high in UIP (70 g/d of CP; 37.1 g/d of UIP). Both experiments were replicated 3 x 3 Latin square designs, with identical feeding and supplementation. Wethers had ad libitum access to the forage mixture and fresh water, and received supplement once daily. In Exp.1, forage intake (percentage of BW) was greatest (P = 0.04) for control, but total DMI (g/d) was greatest (P = 0.05) for lambs consuming supplement. Apparent total-tract OM digestibility was numerically greater (P = 0.11) for supplemented wethers than for controls, whereas total-tract ADF digestibility tended (P = 0.08) to be greater for control wethers. Lambs fed supplements consumed and retained more (P < or = 0.01) N (% of N intake) compared with controls, but no difference (P = 0.22) was observed between low and high UIP treatments. Similar to Exp. 1, forage intake (percentage of BW) tended (P = 0.06) to be greater for control than for supplemented wethers in Exp. 2. Ruminal NDF digestibility was 16.3% greater (P = 0.02) for supplemented wethers than for controls. Postruminal NDF and N digestibilities were greatest (P < or = 0.03) for controls, but apparent OM digestibility did not differ among treatments at all sites. Duodenal N flow was greatest (P = 0.05) for high UIP and least for control wethers. Nonmicrobial N flow was greater (P = 0.02) for high UIP compared with low UIP or controls. Control wethers had greater (P = 0.05) microbial efficiency. Ruminal ammonia concentration tended (P = 0.08) to be greatest for wethers fed low UIP and least for controls, with high-UIP wethers having intermediate ammonia concentrations. Results from these experiments suggest that in lambs fed low-quality forage there was no difference in apparent total-tract digestion or N balance (percentage of N intake) between lambs fed supplements that had the same CP but differed in the proportion of UIP and DIP; however, supplementing protein (regardless of UIP:DIP ratio) to wethers consuming low-quality forage increased N balance.     

Influence of supplemental alfalfa quality on the intake, use, and subsequent performance of beef cattle consuming low-quality roughages.

Three experiments were conducted to evaluate influences of supplemental alfalfa quality on intake and use of low-quality meadow grass roughages (MG) by beef cattle. In Exp. 1, 15 steers (250 kg) were assigned to three treatments: 1) MG (5.2% CP), no supplement; 2) MG plus high-quality alfalfa (18.8% CP); and 3) MG plus low-quality alfalfa (15.2% CP). High- and low-quality alfalfa supplements were fed at .45 and .55% BW, respectively. Total DMI was greater (P < .01) for alfalfa-supplemented steers than for MG. Likewise, intake of digestible DM, DM digestibility (DMD), and ruminal ammonia level were greater (P < .01) for supplemented steers. In Exp. 2, 96 pregnant Hereford x Simmental cows (537 kg; body condition [BC] score 4.86) were assigned to the same treatments as in Exp. 1. For d 0 to 42, cows grazed on 19.1 ha of stockpiled MG (4,539 kg/ha; 6.8% CP), whereas, on d 43 to 84, cows received MG hay (5.2% CP). Supplemented cows gained more BW (P < .01), BC score (P < .01), and had heavier calf birth weight (P < .01) than nonsupplemented cows. However, there were no treatment effects (P > .10) on cow cyclicity, pregnancy rate, or calving interval. In Exp. 3, 90 pregnant Angus x Hereford cows (475 kg; BC score 4.59) were assigned to three treatments: 16.1%, 17.8% or 20.0% CP alfalfa supplement, with levels of .63, .55, and .50% of BW, respectively. Weight gain and BC score for the 84-d study displayed a quadratic response (P < .10), yet represented only 7 kg BW and .2 units of BC score. In conclusion, alfalfa hay supplementation was effective in increasing DMI and digestibility. However, alfalfa hay quality did not dramatically affect BW, BC score, and(or) calf birth weight, when fed on an isonitrogenous basis.     

Effects of wet corn gluten feed and intake level on diet digestibility and ruminal passage rate in steers

Twelve ruminally cannulated Jersey steers (BW = 534 kg) were used in an incomplete Latin square design experiment with a 2 x 2 factorial arrangement of treatments to determine the effects of wet corn gluten feed (WCGF) and total DMI level on diet digestibility and ruminal passage rate. Treatments consisted of diets formulated to contain (DM basis) steam-flaked corn, 20% coarsely ground alfalfa hay, and either 0 or 40% WCGF offered once daily for ad libitum consumption or limited to 1.6% of BW (DM basis). Two consecutive 24-d periods were used, each consisting of 18 d for adaptation, 4 d for collection, and a 2-d in situ period. Rumens of all steers were evacuated once daily at 0, 4, 8, and 12 h after feeding. Chromic oxide (10 g/[steer*d]) was fed as a digestibility marker, and steers were pulse-dosed with Yb-labeled alfalfa hay to measure ruminal particulate passage rate. Dacron bags containing 5 g of steam-flaked corn, WCGF, or ground (2-mm screen) alfalfa hay were placed into the rumens of all steers and removed after 3, 6, 12, or 48 h. Wet corn gluten feed increased percent apparent total-tract digestion of OM (P < 0.01), NDF (P < 0.01), and starch (P < 0.03), decreased (P < 0.01) ruminal total VFA concentration, increased (P < 0.01) ruminal NH3 concentration, and increased (P < 0.01) ruminal pH. Wet corn gluten feed also increased (P < 0.01) ruminal passage rate of Yb. Limit feeding decreased (P < 0.01) percent apparent total-tract digestion of both OM and NDF, ruminal total VFA concentration (P < 0.01), and ruminal fill (P < 0.01), but increased (P < 0.01) ruminal NH3 concentration. Apparent total-tract digestion of starch was not affected (P = 0.70) by level of DMI. A DMI level x hour interaction (P < 0.01) occurred for ruminal pH. Limit feeding increased ruminal pH before and 12 h after feeding, but decreased ruminal pH 4 h after feeding compared with diets offered ad libitum. A diet x DMI level interaction (P < 0.02) occurred for in situ degradation of alfalfa hay, with dietary addition of WCGF increasing (P < 0.02) the extent of in situ alfalfa hay degradation in steers fed for ad libitum consumption. This study suggests that WCGF increases OM and NDF digestion, and that limit feeding diets once daily might depress OM and NDF digestion, possibly due to decreased stability of the ruminal environment.     

Effects of concentrated separator by-product (desugared molasses) on intake, site of digestion, microbial efficiency, and nitrogen balance in ruminants fed forage-based diets

In Exp. 1, 4 ruminally and duodenally cannulated beef steers (444.0 +/- 9.8 kg) were used in a 4 x 4 Latin square with a 2 x 2 factorial treatment arrangement to evaluate the effects of forage type (alfalfa or corn stover) and concentrated separator byproduct (CSB) supplementation (0 or 10% of dietary DM) on intake, site of digestion, and microbial efficiency. In Exp. 2, 5 wethers (44 +/- 1.5 kg) were used in a 5 x 5 Latin square to evaluate the effects of CSB on intake, digestion, and N balance. Treatments were 0, 10, and 20% CSB (DM basis) mixed with forage; 10% CSB offered separately from the forage; and a urea control, in which urea was added to the forage at equal N compared with the 10% CSB treatment. In Exp. 1, intakes of OM and N (g/kg of BW) were greater (P < 0.01) for steers fed alfalfa compared with corn stover. Steers fed 10% CSB had greater (P < 0.08) OM and N intakes (g/kg of BW) compared with 0% CSB-fed steers. Total duodenal, microbial, and nonmicrobial flows of OM and N were greater (P < 0.01) for steers fed alfalfa compared with corn stover. Steers fed 10% CSB had increased (P = 0.02) duodenal microbial flow (N and OM) compared with 0% CSB-fed steers. Forage x CSB interactions (P < 0.01) existed for total tract N digestibility; alfalfa with or without CSB was similar (67.4 vs. 69.5), whereas corn stover with CSB was greater than corn stover without CSB (31.9 vs. -23.9%). True ruminal OM digestion was greater (P < 0.09) in steers fed alfalfa vs. corn stover (73.0 vs. 63.1%) and in steers fed 10 vs. 0% CSB (70.3 vs. 65.8%). Microbial efficiency was unaffected (P > 0.25) by forage type or CSB supplementation. In Exp. 2, forage and total intake increased (linear; P < 0.01) as CSB increased and were greater (P < 0.04) in 10% CSB mixed with forage compared with 10% CSB fed separately. Feeding 10% CSB separately resulted in similar DM and OM apparent total tract digestibility compared with 10% CSB fed mixed. Increasing CSB led to an increase (linear; P < 0.02) in DM, OM, apparent N digestion, and water intake. Nitrogen balance (g and percentage of N intake) increased (linear; P < 0.08) with CSB addition. Feeding 10% CSB separately resulted in greater (P < 0.01) N balance compared with 10% CSB fed mixed. Using urea resulted in similar (P = 0.30) N balance compared with 10% CSB fed mixed. Inclusion of CSB improves intake, digestion, and increases microbial N production in ruminants fed forage-based diets.     

Nonstructural carbohydrate supplementation of yearling heifers and range beef cows

A digestion study with 28 yearling heifers (428 +/- 9.9 kg; Exp. 1) and a 2-yr winter grazing trial with 60 crossbred cows (552 +/- 6.9 kg; Exp. 2) were used to determine the effects of level of nonstructural carbohydrate (NSC) supplementation on intake and digestibility of low-quality forage. Treatments were as follows: 1) control, no supplement; 2) 0.32 kg of NSC (1.8 kg/d of soybean hulls and soybean meal; DM basis); 3) 0.64 kg of NSC (1.7 kg/d of wheat middlings; DM basis); and 4) 0.96 kg of NSC (1.7 kg/d of barley and soybean meal; DM basis). Supplements provided 0.34 kg of CP/d and 5.1 Mcal of ME/d. In Exp. 1, heifers were individually fed hay (5.5% CP, DM basis) and their respective supplements in Calan gates for 28 d. Data were analyzed as a completely randomized design. In Exp. 2, cows were individually fed supplement on alternate days, and grazed a single rangeland pasture stocked at 1.8 ha/ animal unit month. Two ruminally cannulated cows were used per treatment to obtain forage extrusa and to measure in situ DM disappearance (DMD) and carboxymethylcellulase (CMCase) activity of particle-associated ruminal microbes. Data were analyzed as a completely randomized design with the effects of treatment, year, and their interaction. In both experiments, Cr2O3 boluses were used to determine fecal output, individual animal was the experimental unit, and contrasts were used to test linear and quadratic effects of NSC level and control vs. supplemented treatments. In Exp. 1, hay and diet DM, NDF, and CP intakes and digestibilities were increased (P < 0.01) by NSC supplementation compared with the control. In Exp. 2, 72-h in situ DMD and CMCase were decreased linearly (P < 0.08) with increasing NSC supplementation. Intake of forage DM, NDF, and CP was decreased linearly (P < 0.01) with increasing NSC supplementation during both years. Supplementation with NSC decreased (P = 0.01) cow BW loss compared with the control in yr 1, whereas in yr 2, cow BW loss was linearly increased (P = 0.03) by increasing NSC supplementation. Supplements containing NSC improved forage digestion and intake when heifers consumed forage deficient in CP relative to energy (digestible OM:CP > 7), but decreased forage digestion and intake when cows grazed forage with adequate CP relative to energy (digestible OM:CP < 7). Forage and supplement digestible OM:CP seemed to be superior predictors of response to supplementation with NSC compared with forage CP levels alone.     

Influence of protein type and level on nitrogen and forage use in cows consuming low-quality forage

Minimal quantities of ruminally degradable protein from supplements may improve supplement use efficiency of ruminants grazing dormant forages. In Exp. 1, N retention, ruminal NH(3), serum urea N, and NDF digestibility were evaluated for 12 ruminally cannulated cows (Bos spp.) in an incomplete Latin Square design with 3 periods of 42 d each. Cows were fed weeping lovegrass [Eragrostis curvula (Schrad.) Nees] hay (4.1% CP, 75% NDF, OM basis) at 1.3 % BW/d and offered 1 of 3 sources of CP [urea, cottonseed (Gossypium spp.) meal (CSM); or 50% blood meal and 50% feather meal combination (BFM)] fed to supply 0, 40, 80, or 160 g/d of CP. Beginning on d 22 of supplementation, ruminal contents and serum samples were collected at -2, 0, 3, 6, 9, 12, 18, 24, 30, 36, and 48 h relative to the morning offering of hay. On Day 24, feces and urine were collected for 72 h. In Exp. 2, 4 ruminally cannulated steers were used in a replicated 4 by 4 Latin Square to evaluate use of supplements differing in quantity and ruminal CP degradability. Steers were fed 6.8 kg/d chopped sudangrass [Sorghum bicolor (L.) Moench nothosubsp. drummondii (Steud.) de Wet ex Davidse] hay (3.7% CP, 74% NDF on OM basis) and supplemented with 56 g/d of a salt mineral mix (CON); CON + 28 g/d blood meal + 28 g/d feather meal (BFM); CON + 98 g/d CSM (LCS); or CON + 392 g/d CSM (HCS). Treatments provided 0, 40, 40, or 160 g/d of CP for CON, BFM, LCS, and HCS respectively. In Exp. 1, N use and total tract NDF digestibility were not affected by protein sources or amounts (P ≥ 0.18). Ruminal NH(3) concentrations exhibited a quadratic response over time for UREA (P < 0.05) and was greater with increasing inclusion of urea (P < 0.05); whereas BFM or CSM did not differ (P > 0.05) by amount or across time. In Exp. 2, supplementation had a tendency (P = 0.09) to increase DM disappearance. Supplementation also increased (P < 0.01) serum glucose concentrations; however, no difference (P ≥ 0.28) was found between supplements. Serum urea N and ruminal NH(3) concentrations were increased (P ≤ 0.01) in steers fed HCS. Feeding low quantities of a high-RUP supplement maintained rumen function without negatively affecting DM or NDF digestibility of a low-quality forage diet.     

Influence of slice baling on feeding value of alfalfa hay in receiving and finishing diets for feedlot cattle

Three studies were conducted to evaluate the feeding value of slice alfalfa hay in feedlot diets. In Exp. 1, 108 steer calves (183.1 +/- 1.2 kg initial BW; 6 pens/treatment) were used in a completely randomized design to evaluate the effect of baling method on performance and morbidity of newly received calves. The study lasted 28 d. Treatments consisted of a 65% concentrate receiving diet containing 1) ground or 2) slice alfalfa hay. Steer calves were fed daily at 0800 h. Animals also received long-stem sudangrass hay the first 7 d. Steers were weighed on d 0, 16, and 28. Feed, sudangrass hay, or feed plus sudangrass hay intakes were not affected (P > 0.25) by treatment. Conversely, ADG from d 0 to 16 was greater (P < 0.001) for slice than ground (1.27 vs. 0.81 +/- 0.067 kg/d, respectively) and from d 0 to 28 (1.23 vs. 0.91 +/- 0.042 kg/d, respectively). In addition, G:F was greater (P < 0.001) for slice than ground hay from d 0 to 16 (0.39 vs. 0.25 +/- 0.021), and from d 0 to 28 (0.31 vs. 0.24 +/- 0.013 for slice and ground, respectively). Moreover, morbidity (40.5 +/- 3.9%; P = 0.20) and retreatment rates (30.7 +/- 7.5%; P = 0.14) were similar for slice and ground. In Exp. 2, 176 crossbred steers (393.9 +/- 10.8 kg initial BW) were used in an 84-d feeding experiment (4 pens/treatment) in a randomized complete block experimental design with a 2 x 2 factorial arrangement of treatments to evaluate effects of alfalfa baling method (ground or slice) and forage level (8 or 14%) on growth performance. Experimental diets were based on steam-flaked corn. Daily BW gain was greater (P = 0.10) for steers consuming ground compared with the slice hay diet. A baling method x forage level interaction (P = 0.07) was observed for DMI. Baling method did not (P = 0.98) influence DMI with 8% roughage level. But with 14% roughage, DMI was greater (P = 0.02) for steers consuming ground hay than the slice diet. The G:F ratio was affected (P = 0.03) only by forage level (0.194 vs. 0.182 +/- 0.003 for 8 and 14% roughage, respectively). In Exp. 3, 4 ruminally cannulated mixed-breed steers were used in a 4 x 4 Latin square design to evaluate effects on digestive function. No baling method effects (P >or= 0.16) were detected for DM, OM, CP, or NDF intakes or DM, OM, and NDF total tract digestibility. Digestibility of NDF and OM were greater (P 相似文献   

Effects of copper oxide bolus administration or high-level copper supplementation on forage utilization and copper status in beef cattle

Two experiments were conducted to study effects of high-level Cu supplementation on measures of Cu status and forage utilization in beef cattle. In Exp. 1, eight steers randomly received an intraruminal bolus containing 12.5 g of CuO needles (n = 4) or no bolus (n = 4). Steers were individually offered free-choice ground limpograss (Hemarthria altissima) hay. On d 12 (Period 1) and d 33 (Period 2) steers were placed in metabolism crates, and total forage refused and feces produced were collected for 7 d. Daily samples of forage offered and refused and of feces excreted for each steer within period were analyzed for DM, ash, NDF, ADF, and CP. Liver biopsies were collected on d 0, 12, and 33. Copper oxide bolus administration resulted in greater (P < 0.03) liver Cu (DM basis) accumulation in Period 1 (556 vs. 296 mg/kg) and Period 2 (640 vs. 327 ppm). Apparent digestibilities of NDF and CP were greater (P < 0.04) for steers receiving no bolus in Period 2 (62.2 vs. 57.1% and 50.2 vs. 43.4% for NDF and CP digestibility, respectively). In Exp. 2, 24 crossbred heifers were assigned to individual pens and received a molasses-cottonseed meal supplement fortified with 0, 15, 60, or 120 ppm of supplemental Cu (Cu sulfate; six pens per treatment). All heifers were offered free-choice access to ground stargrass (Cynodon spp.) hay. Heifer BW and liver biopsies were collected on d 0, 42, and 84. Forage refusal was determined daily, and diet DM digestibility was estimated over a 21-d period beginning on d 42. Heifers consuming 120 ppm of supplemental Cu gained less (P < 0.05; 0.04 kg/d) than heifers consuming 15 (0.19 kg/d) and 60 ppm of Cu (0.22 kg/d), but their ADG did not differ from that by heifers consuming no supplemental Cu (0.14 kg/d; pooled SEM = 0.07). Heifers supplemented with 15 ppm of Cu had greater (P < 0.05) liver Cu concentrations on d 84 than those on the 0-ppm treatment and the high-Cu treatments (60 and 120 ppm). Forage intake was less (P = 0.07) by heifers receiving no supplemental Cu than by heifers on all other treatments (6.6 vs. 5.8 +/- 0.37 kg/d). Apparent forage digestibility was not affected by Cu treatment. These data suggest that high rates of Cu supplementation (Cu sulfate; > 60 ppm of total Cu) resulted in less liver Cu accumulation by beef heifers compared with heifers consuming diets supplemented with moderate dietary Cu concentrations (i.e., 15 ppm). As well, the administration of CuO boluses might depress the digestibility of forage nutrient fractions in steers.     

Wet corn gluten feed and alfalfa hay combinations in steam-flaked corn finishing cattle diets

One finishing trial and one digestibility trial were used to evaluate wet corn gluten feed (WCGF) and alfalfa hay (AH) combinations in steam-flaked corn (SFC) finishing diets. In Exp. 1, 631 crossbred heifers (initial BW = 284 +/- 7.9 kg) were fed SFC-based diets containing combinations of WCGF (25, 35, or 45% of diet DM) and AH (2 or 6% of dietary DM) in a 2 x 3 factorial arrangement of treatments. No interactions existed between WCGF and AH for heifer performance. Increasing dietary WCGF linearly decreased gain efficiency (P < 0.01), dietary NEg concentration (P < 0.05), and 12th-rib fat thickness (P = 0.10). Cattle fed 35% WCGF had the lowest occurrence of abscessed livers, resulting in a quadratic response (P < 0.05) as dietary WCGF increased. In Exp. 2, 12 ruminally cannulated Jersey steers (585 kg) were fed SFC-based diets containing combinations of WCGF (25 or 45% of diet DM) and AH (0, 2, or 6% of diet DM) in an incomplete Latin square design with a 2 x 3 factorial arrangement of treatments. Starch intake was lower (P < 0.05), but NDF intake was greater (P < 0.05) as AH and WCGF increased in the diet. Ruminal pH was increased by AH (linear, P < 0.05) and tended (P < 0.07) to increase with WCGF. Feeding 2% AH led to the greatest ruminal NH3 but the lowest total VFA and propionate (quadratic, P < 0.05). Addition of AH to diets containing 25% WCGF increased acetate to a greater extent than addition to diets containing 45% WCGF (AH x WCGF interaction, P < 0.05). Feeding 45% WCGF tended to increase passage rate (P = 0.17) and decrease (P < 0.05) total tract OM digestibility but increase (P < 0.05) in situ degradation of DM from AH and WCGF. Interactions between AH and WCGF existed (P < 0.05) for ruminal fluid volume (quadratic effect of AH x WCGF level), in situ SFC degradation (linear effect of AH x WCGF level), and in situ rate of WCGF DM disappearance (quadratic effect of AH x WCGF level). We conclude that AH levels may be decreased when WCGF is added to SFC diets as 25% or more of the dietary DM.     

Effects of supplemental degradable intake protein on utilization of medium- to low-quality forages

Three independent experiments were conducted each using 16 ruminally fistulated beef steers fed bermudagrass (8.2% CP, 71% NDF; Exp. 1), bromegrass (5.9% CP, 65% NDF; Exp. 2), or forage sorghum (4.3% CP, 60% NDF; Exp. 3) hays to evaluate the effects of increasing level of supplemental degradable intake protein (DIP) on forage utilization. In each experiment, steers were blocked by weight and assigned to one of four treatments, and hay was offered to each steer at 130% of average voluntary intake for the preceding 5-d period. Supplemental DIP (sodium caseinate) was placed in the rumen at 0700, immediately before feeding forage. Levels of DIP supplementation were .041, .082, and .124% BW; the control received no supplemental DIP. Following a 10-d adaptation, intake and total fecal output were measured for 7 d. In Exp. 1, neither forage OM intake (FOMI) nor fiber (NDF) digestion were influenced (P > or = .20) by increasing level of DIP supplementation. The DIP supplied by the bermudagrass hay was estimated to be 8.2% of the total digestible OM intake (TDOMI) for control steers. In Exp. 2, increasing level of supplemental DIP did not affect (P > or = .26) FOMI but tended to increase total OM intake linearly (TOMI; P = .10). The tendency for a rise in TOMI coupled with a slight numeric increase in digestion resulted in an increase (linear; P = .06) in TDOMI. In the treatment group in which the maximum TDOMI was observed (supplemental DIP treatment of .082% BW), total DIP intake constituted approximately 9.8% of the TDOMI. In Exp. 3, FOMI, TOMI, organic matter digestion (OMD), and TDOMI were improved (P < .01) by increasing amounts of supplemental DIP. Although there was some evidence of a tendency for a decrease in the magnitude of change in TDOMI in response to increasing DIP supplementation, a clear plateau was not achieved with the levels of supplement provided. When the highest level of supplemental DIP was fed, DIP constituted approximately 12.8% of the TDOMI. In conclusion, significant variation was observed among forage in the amount of DIP needed to maximize intake and digestion when expressed in relationship to the digestible OM.     

Intake, digestion, and digestive characteristics of Neotyphodium coenophialum-infected and uninfected fescue by heifers offered hay diets supplemented with Aspergillus oryzae fermentation extract or laidlomycin propionate

Tarentaise heifers fitted with a rumen cannula (539 +/- 7.5 and 487 +/- 15.7 kg avg initial BW in Exp. 1 and 2, respectively) were used in two Latin square metabolism experiments having 2 x 2 factorial treatment arrangements to determine the effects of supplementation with Aspergillus oryzae fermentation extract (AO) or laidlomycin propionate (LP) on intake, digestion, and digestive characteristics of Neotyphodium coenophialum-infected (IF) or uninfected (FF) tall fescue (Festuca arundinacea) hay diets consumed ad libitum. Heifers were housed in individual stanchions in a metabolism facility with ambient temperatures controlled to range between 26.7 and 32.2 degrees C daily. Total feces and urine were collected for 5 d following a 21-d dietary adaptation period. In situ DM and NDF disappearance and ruminal fermentation characteristics were also determined. In Exp. 1, DMI was 24% greater (P < 0.01) by heifers offered FF than by those offered IF (6.7 vs 5.4 kg/d). Heifers fed 2 g/d AO tended (P = 0.09) to consume 4% more DM than those fed a diet without AO. Degradable DM and NDF fractions of IF were greater (P < 0.01) than those of FF, but AO supplementation did not affect situ disappearance (P > or = 0.42). In Exp. 2, DMI was 18.9% greater (P < 0.01) by heifers offered FF than by those offered IF (6.6 vs 5.5 kg/d). Heifers fed LP (50 mg/d) consumed 10.6% less (P < 0.05) DM than those not fed LP (5.7 vs 6/5 kg/d). Digestibility of NDF tended to be greater (P = 0.08) and digestibility of ADF was greater (P < 0.05) from FF than from IF. Conversely, apparent N absorption (%) was greater (P < 0.05) from IF than from FF. Heifers fed LP had lower (P < 0.05) ADF digestibility than those not fed LP. In situ degradable DM and NDF fractions were greater (P < 0.01) from IF than from FF. Diets supplemented with LP had higher (P < 0.01) indigestible DM and NDF fractions than those without LP. Propionic acid and total VFA concentrations were greater (P < 0.05) from heifers offered FF than from those offered IF and from heifers fed LP than from those not fed LP. Therefore, it appears the major effect of N. coenophialum was a reduction in forage intake and total-tract fiber digestibility in certain situations. Response to the feed additives was similar whether heifers were offered IF or FF and no evidence was apparent that either additive would improve performance substantially by animals consuming low-quality fescue hay diets.     

Intake and digestibility of low-quality native grass hay by beef cows supplemented with graded levels of soybean hulls

Twelve Hereford cows and four mature, ruminally cannulated Hereford x Angus heifers were fed supplements providing either 0 (control), 1, 2, or 3 kg/d of soybean hulls and including 440 g of protein/d (cottonseed meal was used to equalize protein intake) to determine the effects of supplementation on intake and utilization of low-quality native grass hay. Cattle were housed in individual pens and fed coarsely chopped (5-cm screen) native grass hay harvested in mid-November (4.1% CP, 76.9% NDF). Hay OM intake peaked (quadratic, P = .04) at 10.1 kg/d with 1 kg of soybean hulls and decreased when 2 kg (9.8 kg/d) or 3 kg (9.1 kg/d) of soybean hulls were fed. Although hay intake decreased when soybean hulls replaced cottonseed meal, feeding 3 kg soybean hulls decreased hay OM intake by only .64 kg. Total OM digestibility increased linearly (P = .009) with added increments of soybean hulls (45.8%, 46.2%, 46.6% and 48.6% for 0 through 3 kg soybean hulls/d, respectively), indicating that hulls were more digestible than the hay. Digestibility of NDF was not affected (P = .14) by level of soybean hull supplementation, although ADF digestibility increased (linear, P = .03). Increases in OM intake and digestibility with soybean hulls combined to increase digestible OM intake (linear, P = .0001). Soybean hull supplementation increased ruminal VFA concentrations (linear, P = .04) and the molar proportion of propionate (linear, P = .006).(ABSTRACT TRUNCATED AT 250 WORDS)     

Optimizing nitrogen utilization in growing steers fed forage diets supplemented with dried citrus pulp

Our objectives were to compare the effects of sources of supplemental N on ruminal fermentation of dried citrus pulp (DCP) and performance of growing steers fed DCP and bahiagrass (Paspalum notatum) hay. In Exp. 1, fermentation of DCP alone was compared with that of isonitrogenous mixtures of DCP and solvent soybean meal (SBM), expeller soybean meal (SoyPLUS; SP), or urea (UR). Ground (1 mm) substrates were incubated in buffered rumen fluid for 24 h, and IVDMD and fermentation gas production kinetics and products were measured. Nitrogen supplementation increased (P < 0.10) ruminally fermentable fractions, IVDMD, pH, and concentrations of NH3 and total VFA, but reduced the rate of gas production (P < 0.10) and the lag phase (P < 0.01). Supplementation with UR vs. the soy-based supplements increased ruminally fermentable fractions (P < 0.05) and concentrations of total VFA (P < 0.10) and NH3 (P < 0.01), but these measures were similar (P > 0.10) between SBM and SP. In Exp. 2, 4 steers (254 kg) were fed bahiagrass hay plus DCP, or hay plus DCP supplemented with CP predominantly from UR, SBM, or SP in a 4 x 4 Latin square design, with four 21-d periods, each with 7 d for DMI and fecal output measurement. Nitrogen-supplemented diets were formulated to be isonitrogenous (11.9% CP), and all diets were formulated to be isocaloric (66% TDN). Intake and digestibility of DM, N, and ADF were improved (P < 0.05) by N supplementation. Compared with UR, the soy-based supplements led to greater (P < 0.05) DM and N intakes and apparent N and ADF digestibilities. Plasma glucose and urea concentrations increased (P < 0.10) with N supplementation and were greater (P < 0.01) for the soy-based supplements than for UR. Intake, digestibility, and plasma metabolite concentrations were similar (P > 0.1) for SBM and SP. In Exp. 3, 24 steers (261 kg) were individually fed bahiagrass hay plus DCP (control), or hay plus DCP supplemented with CP predominantly from UR or SBM. Over 56 d, DMI and ADG were greatest (P < 0.05) in steers fed SBM. Nitrogen supplementation increased (P < 0.05) DMI, ADG, and G:F. However, SBM supplementation produced greater (P < 0.05) DMI and ADG and similar (P > 0.05) G:F compared with UR supplementation. We conclude that supplemental N is important to optimize ruminal function and performance of growing steers fed forage diets supplemented with DCP. Diets with supplemental N mainly from SBM improved diet digestibility and animal performance beyond that achieved by UR.