Supplemental Degradable Intake Protein Research Articles

Infrequent dietary supplementation feeding in beef cattle: animal responses and factors affecting its success

Abstract Infrequent supplementation (IS; i.e., feeding supplement to animals at frequency less than daily) as opposed to frequent (i.e., daily) could be used as a management tool to improve economic returns of extensive beef production systems by reducing costs associated with the delivery of supplement to cattle. However, previous reports on the effectiveness of IS on production responses in beef cattle are ambiguous and the factors affecting responses to IS by beef cattle are poorly known. The objective of this study was to summarise available data related to the success of IS in beef cattle fed a low quality diet. Additionally, we aimed to identify other potential factors, such as supplement type and composition, forage quality, supplemental degradable intake protein, breed of cattle and environment, which may influence the animal’s response to IS. The results of our study suggest that no single factor could fully explain the discrepancies among studies and, therefore, each of these factors should not be treated in isolation. Cattle maintained with IS appear to be more efficient using the urea recycling mechanism to maintain level of ruminal ammonia during the non-supplemental feeding days. Systematic approaches compiling all potential factors affecting responses of beef cattle to IS are required to determine the likelihood of success with IS for a given farming system.

In vivo ruminal degradation characteristics and apparent digestibility of low-quality prairie hay for steers consuming monensin and Optimase.

Seven ruminally cannulated crossbred steers (BW = 720 ± 62 kg) were used in a randomized crossover design (4 periods, each 18 d) to evaluate in vivo rumen characteristics and apparent digestibility of steers consuming low-quality prairie hay and 1 of 4 isonitrogenous protein supplements. Treatments included 1) 40% CP (DM basis) cottonseed meal and wheat middlings-based supplement (Control), 2) a cottonseed meal and wheat middlings-based supplement with slow-release urea and a fibrolytic feed enzyme (Optimase; Alltech, Inc., Nicholasville, KY) designed to replace 30% of plant-based CP provided in the Control (OPT), 3) the Control plus 0.40 mg∙kg BW∙d monensin (Rumensin 90; Elanco Animal Health, Greenfield, IN; MON), and 4) the OPT plus 0.40 mg∙kg BW∙d monensin (COMBO). Steers were allowed ad libitum access to prairie hay (5.0% CP and 76% NDF) and were provided each respective supplement at 0800 h daily at a rate of 1.0 g/kg of BW. Steers were adapted to diets for 10 d before sample collection. Beginning on d 11, DMI was measured and samples were collected to determine apparent digestibility. On d 15 of the 18-d period, rumen fluid was collected 10 times over a 24-h period. Forage DMI was greater ( ≤ 0.02) for steers consuming the OPT compared with steers consuming the MON or COMBO, although forage DMI was not different ( = 0.10) among steers consuming the Control compared with steers consuming the OPT, MON, or COMBO. Steers fed the MON and COMBO had lower ( ≤ 0.05) passage rate compared with steers fed the Control and the OPT. The MON-fed steers had lower ( = 0.01) ruminal pH and increased ( = 0.03) propionate as a percentage of total VFA production. A time × treatment ( = 0.01) interaction was observed for ruminal NH-N due to a rapid (0 to 1 h after feeding) increase followed by a quick (1 to 4 h after feeding) decline in NH-N by steers consuming the OPT and COMBO that was not observed for steers consuming all other treatments. Apparent digestibility of DM ( = 0.01) and NDF ( = 0.03) were improved for steers fed the COMBO supplement compared with steers consuming all other experimental supplements. This work suggests that the OPT may be an effective replacement for a portion of supplemental degradable intake protein in low-quality forage. Further research is necessary to determine if the combination of monensin and the Optimase consistently improves low-quality forage utilization.

Effect of degradable intake protein supplementation in finishing diets containing dried distillers grains or wet distillers grains plus solubles on performance and carcass characteristics

<h2>ABSTRACT</h2> Two finishing trials were conducted to determine whether supplemental degradable intake protein is necessary to optimize performance in dry-rolled corn (DRC) based finishing diets containing distillers grains. Diets without urea were deficient in degradable intake protein based on the NRC (1996) recommendations, yet all diets had positive metabolizable protein balances. In Exp. 1, individually fed, crossbred heifers (n = 58; BW=383 ± 25 kg) were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments. Dietary treatments contained 10 or 20% dried distillers grains replacing DRC, with or without 0.80 or 0.63% urea, respectively (DM basis). Blood samples were analyzed for BUN. Heifers receiving urea or 20% dried distillers grains (P < 0.01) had greater BUN concentration than did heifers not receiving urea or fed 10% dried distillers grains, respectively. In Exp. 2, pen-fed, crossbred steers (n = 336; initial BW=365 ± 31 kg) were assigned randomly within block to 1 of 24 pens in a randomized complete block design with 3 treatments. Dietary treatments were 0, 0.5, or 1.0% urea added to a DRC diet containing 25% wet distillers grains plus solubles (DM basis). Marbling tended to decrease linearly (P = 0.09) as urea level increased. However, no other significant differences (P > 0.10) were observed for performance or carcass characteristics for either experiment. These data indicate supply of ruminal degradable intake protein was adequate to maintain performance when at least 10% distillers grains was included in DRC diets.

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 supplemental energy and/or degradable intake protein on performance, grazing behavior, intake, digestibility, and fecal and blood indices by beef steers grazed on dormant native tallgrass prairie1,2

To evaluate the effects of balancing total diet degradable intake protein with dietary total digestible nutrients (TDN), we conducted two studies during 2 yr with 100 (302 +/- 8 kg initial BW) mixed-breed yearling steers and 12 ruminally cannulated steers (526 +/- 28 kg). Steers individually received one of four supplements 5 d/wk while grazing dormant native tallgrass prairie. Supplements included: 1) corn and soybean meal, balanced for total diet degradable intake protein in relation to total diet TDN (CRSBM), 2) corn and soybean hulls, equal in supplemental TDN to CRSBM (CORN), 3) soybean meal, equal in supplemental degradable intake protein to CRSBM (SBM), or 4) a cottonseed hull-based control supplement (CONT). At each feeding (5 d/wk), steers consumed 13.6, 13.6, or 4.2 g of dry matter/kg of body weight, or 178 g of DM, respectively, of supplement. Steers fed CRSBM had greater (P < 0.01) average daily gain than cattle fed CORN or SBM. Feeding soybean meal (CRSBM, SBM) resulted in improved (P < 0.01) efficiency of supplement. Grazing time, intensity, and harvesting efficiency were reduced (P < 0.05) by corn supplementation (CRSBM and CORN), whereas the number of grazing bouts per day was increased (P < 0.08). Intake and digestibility of forage organic matter were reduced (P < 0.01) for steers supplemented with corn (CORN and CRSBM) vs cattle not fed corn (SBM and CONT). Total diet digestibility (P < 0.12) and digestible organic matter intake (P < 0.01) were greater for CRSBM-fed steers than for cattle fed either CORN or SBM. Steers fed CRSBM had greater (P < 0.01) fecal nitrogen and serum insulin than cattle fed CORN or SBM. Corn-fed cattle had lesser (P < 0.01) fecal pH and ADF concentrations than steers not consuming grain. Cattle fed supplements with soybean meal (CRSBM and SBM) had greater (P < 0.01) serum urea nitrogen than steers fed supplements without soybean meal (CORN, CONT). Supplemented steers grazing dormant tallgrass prairie had a greater rate of gain, with the greatest response in animal performance occurring when grain supplements were balanced for total diet degradable intake protein in relation to total diet TDN. These results lead us to suggest that grain-supplemented cattle grazing dormant tallgrass prairie require a balance of total diet degradable intake protein in relation to total diet TDN to optimize animal performance.

Effect of increasing proportion of supplemental N from urea in prepartum supplements on range beef cow performance and on forage intake and digestibility by steers fed low-quality forage.

Four experiments were conducted to evaluate the influence of changing the proportion of supplemental degradable intake protein (DIP) from urea on forage intake, digestion, and performance by beef cattle consuming either low-quality, tallgrass prairie forage (Exp. 1, 2, and 4) or forage sorghum hay (Exp. 3). Experiments 1, 2, and 3 were intended to have four levels of supplemental DIP from urea: 0, 20, 40, and 60%. However, refusal to consume the 60% supplement by cows grazing tallgrass prairie resulted in elimination of this treatment from Exp. 1 and 2. Levels of supplemental DIP from urea in Exp. 4 were 0, 15, 30, and 45%. Supplements contained approximately 30% CP, provided sufficient DIP to maximize digestible OM intake (DOMI) of low-quality forage diets, and were fed to cows during the prepartum period. In Exp. 1, 12 Angus x Hereford steers (average initial BW = 379) were assigned to the 0, 20, and 40% treatments. Forage OM intake, DOMI, OM, and NDF digestion were not affected by urea level. In Exp. 2, 90 pregnant, Angus x Hereford cows (average initial BW = 504 kg and body condition [BC] = 5.0) were assigned to the 0, 20, and 40% treatments. Treatment had little effect on cow BW and BC changes and calf birth weight, ADG, or weaning weight. However, pregnancy rate tended to be lowest (P = 0.13) for the greatest level of urea. In Exp. 3, 120 pregnant, crossbred beef cows (average initial BW = 498 kg and BC = 4.6) were assigned to the 0, 20, 40, and 60% treatments. Prepartum BC change tended (P = 0.08) to be quadratic (least increase for 60% treatment), although BW change was not statistically significant. Treatment effect on calf birth weight was inconsistent (cubic; P = 0.03), but calf ADG and weaning weight were not affected by treatment. Pregnancy rate was not affected by prepartum treatment. In Exp. 4, 132 pregnant, Angus x Hereford cows (average initial BW = 533 and BC = 5.3) were assigned to the 0, 15, 30, and 45% treatments. Prepartum BC loss was greatest (quadratic; P = 0.04) for the high-urea (45%) treatment, although BW loss during this period declined linearly (P < 0.01). Prepartum treatment did not affect pregnancy rate, calf birth weight, or ADG. In conclusion, when sufficient DIP was offered to prepartum cows to maximize low-quality forage DOMI, urea could replace between 20 and 40% of the DIP in a high-protein (30%) supplement without significantly altering supplement palatability or cow and calf performance.

Determining the influence of different levels of urea supplementation when beef cows grazing winter pasture are supplemented at different frequencies during the prepartum period (2002)

One hundred sixty spring-calving Hereford x Angus cows grazing low-quality, tallgrass-prairie range during the winter of 2000-2001 were supplemented before calving either daily or three times weekly. The supplement contained 40% CP with 0, 15, 30, or 45% of the supplemental degradable intake protein from urea. Supplement was fed at 4 lbs/head daily to cows receiving supplement daily. Cows receiving supplement three times weekly were fed the same amount of weekly supplement, but split equally among their supplementation events. After calving, all cows received a supplement without urea on a daily basis. In general, prepartum supplements that contained more urea prompted greater body weight loss; however, the effect of increasing urea was most noticeable when supplements were fed only three times weekly. When averaged across supplementation frequencies, increasing the level of supplemental urea tended (P=0.15) to decrease pregnancy rate in beef cows that had received urea supplementation before calving.

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.

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.

First Limiting Nutrient for Summer Calving Cows Grazing Autumn-Winter Range

Two trials were conducted in 1994, 1995, and 1996 to determine the first limiting nutrient for summer calving cows grazing Sandhills range. In Trial 1, 48 lactating summer calving cows grazing native range during the breeding season were assigned to 1 of 4 supplement treatments: 1) control-no supplement, 2) energy, 3) degradable intake protein (DIP), and 4) DIP + undegraded intake protein (UIP). Cows were group-fed supplements in 8 pastures (2 pastures/treatment). The trial began 4 September and ended 4 November each year. Diet samples from esophageally fistulated cows averaged 7.5% crude protein and 54.5% in vitro organic matter digestibility. Supplemented cows lost less body condition compared to control cows (P = 0.04). Cow and calf weight gains were increased by supplemental DIP or DIP + UIP combination compared to energy supplement (P = 0.09 and 0.08, respectively). Forage intake and digestibility were not different among treatments (P > 0.20). Milk production was lower for non-supplemented than supplemented cows (P = 0.10). Trial 2 began 5 November and ended 10 January in 1994-1995, 1995-1996, and 1996-1997. Treatments and pastures were the same as described in Trial 1, however, only 40 cows were used. In Trial 2, diet samples from esophageally fistulated cows averaged 6.2% crude protein and 52.3% in vitro organic matter digestibility. No differences (P > 0.10) in body condition score were detected. Total organic matter intake was lower for control compared to supplemented treatments (13.5 vs.15.5 kg day(-1); P < 0.10). We concluded that DIP was the first limiting nutrient for summer calving cows during the breeding season and during autumn-winter lactation after the breeding season.

Effects of ruminal administration of supplemental degradable intake protein and starch on utilization of low-quality warm-season grass hay by beef steers.

Hereford x Angus steers were used in a 13-treatment, four-period, incomplete Latin square design to examine the effects of starch and degradable intake protein (DIP) supplements on forage utilization and ruminal function. Steers were given ad libitum access to low-quality hay (4.9% CP) and were not supplemented (NS) or received different amounts of starch (cornstarch grits; 0, .15, and .3% of initial BW) and DIP (Na-caseinate; .03, .06, .09, and .12% of initial BW) administered via ruminal fistulae in a 3 x 4 factorial arrangement of treatments. Supplemented steers consumed more (P < .01) forage OM, total OM, NDF, and digestible OM (DOM) than NS steers. Forage OM, total OM, NDF, and DOM intakes increased linearly (P < .01) as the amount of supplemental DIP increased. The addition of starch to supplements linearly decreased ( P < .01) the intake of forage OM, NDF, and DOM. The digestion of DM, OM, and NDF increased linearly (P < .01) with supplemental DIP and decreased linearly (P < or = .06) with supplemental starch. Particulate and liquid passages generally increased with DIP; however, starch level influenced the nature of the response (P = .03 and .06, respectively). Similarly, ruminal acid detergent-insoluble ash content generally decreased as starch increased, but the effect was dependent on DIP level (P < .01). Supplementation increased (P < .01) ruminal NH3 and total VFA and decreased (P < .01) ruminal pH relative to NS. All treatments supported average pH values in a range (6.3 to 6.7) unlikely to inhibit fibrolytic bacteria. Ruminal NH3 concentration increased quadratically (P = .03) with DIP and decreased linearly (P = .02) with starch. As DIP increased, total VFA concentration increased linearly (P = .02). Providing supplemental DIP to steers fed low-quality forage increased OM intake and digestion, whereas addition of starch to supplements decreased forage intake and digestion.

Effects of different supplemental sugars and starch fed in combination with degradable intake protein on low-quality forage use by beef steers.

Twenty ruminally fistulated steers (Exp. 1, 448 kg and Exp. 2, 450 kg) were used in two consecutive randomized complete block experiments with five treatments in each experiment. The purpose was to evaluate the impact of feeding different supplemental sugars or starch in combination with supplemental degradable intake protein (DIP) on the utilization of low-quality tallgrass-prairie hay. In Exp. 1, steers were given ad libitum access to forage and, except for the negative control (NC), received a limited supply (insufficient to maximize forage use) of supplemental DIP (.031% BW/d, DM basis). In addition to the NC, this experiment included four supplementation treatments in which one of four carbohydrate (CHO) sources (starch, glucose, fructose, or sucrose) was fed at .30% BW of DM/d. In Exp. 2, the treatment structure was identical except that the supplemental DIP level (.122% BW, DM basis) was near the level needed to maximize forage use. Forage OM intake (FOMI) was not affected (P> or =.26) by supplementation in Exp. 1 but was increased (P = .05) in Exp. 2. However, no difference (P> or =.46) in FOMI occurred among CHO sources in either experiment. Total OM and digestible OM intakes were increased (P<.01) by supplementation in both experiments. In Exp. 1, no difference (P>.26) in OM digestion (OMD) occurred among treatments. In Exp. 2, supplementation increased (P<.01) OMD. Additionally, sugars yielded a higher (P = .04) OMD than starch, and the monosaccharides yielded a higher (P = .02) OMD than sucrose. In Exp. 1, NDF digestion (NDFD) was decreased (P = .02) by supplementation, but no differences (P> or =.21) occurred among CHO sources. In Exp. 2, NDFD was increased (P = .03) by supplementation. Additionally, sugars led to higher (P = .05) NDFD than starch, and the monosaccharides led to higher (P = .03) NDFD than sucrose. In both experiments, discernible patterns were observable with regard to the effects of supplementation and type of supplemental CHO on ruminal fermentation characteristics. In conclusion, even though some consistency in fermentation profiles for different carbohydrate sources was evident in both experiments, forage intake and digestion responses were not consistent across experiments. This raises the possibility that carbohydrate source may interact with the amount of supplemental DIP fed and, as such, deserves additional investigation.

Effects of level and source of carbohydrate and level of degradable intake protein on intake and digestion of low-quality tallgrass-prairie hay by beef steers.

Ruminally fistulated steers (n = 13; 263 kg) were used in an incomplete Latin square with 13 treatments and four periods to evaluate the effects of level and source of supplemental carbohydrate (CHO) and level of degradable intake protein (DIP) on the utilization of low-quality, tallgrass-prairie hay. Steers were given ad libitum access to forage (5.7% CP, 2.6% DIP, and 74.9% NDF). The supplementation treatments were fashioned as a 2x3x2 factorial arrangement plus a negative control (NC; no supplement). The factors included two DIP levels (.031 and .122% BW) and three CHO sources (starch, glucose, and fiber) fed at two levels (.15 and .30% BW) within each level of DIP supplementation. The effect of supplementation on forage OM intake (FOMI) was dependent (P<.01) on level and source of CHO and level of DIP fed. When DIP was low, forage, total, and digestible OM intakes were generally greater for the starch treatment than for the nonstarch treatments. However, when the DIP level was high, intakes were greater for the nonstarch (i.e., fiber and glucose) treatments. Generally, FOMI decreased (P<.01) when more supplemental CHO was provided. Supplementation typically increased fiber digestion, but the response was dependent (P<.01) on level and source of CHO and level of DIP. Generally, supplements with low levels of CHO improved NDF digestion (NDFD). However, supplements with the high level of CHO decreased NDFD, except for fiber at the high level of DIP. Organic matter digestion was increased by supplementation, but the impact of increasing CHO was dependent (P<.01) on source of CHO and level of DIP. Supplementation treatments had significant impact on ruminal pH, NH3 N, and the total concentration of organic acids as well as their relative proportions. In conclusion, supplemental DIP enhanced the use of low-quality forage; however, the impact of supplemental CHO on low-quality forage use was dependent on source and level of CHO offered, as well as the level of DIP provided.

Effect of supplemental carbohydrate source on the utilization of low-quality tallgrass-prairie hay by beef steers (1998)

Twenty ruminally fistulated steers were used in different two experiments to evaluate the effects of supplemental carbohydrate source (starch, glucose, fructose, or sucrose) fed at .3% BW/day on the utilization of low-quality tallgrass-prairie hay. In Experiment 1, all supplemental carbohydrates were fed with a low level of supplemental degradable intake protein. In Experiment 2, the level of supplemental degradable intake protein was high. Intake of the tallgrass-prairie hay was not affected significantly by supplementation in either experiment, but as a result of the added carbohydrate, total intake was increased. When supplemental protein intake was inadequate, supplemental carbohydrates depressed digestion, but when supplemental protein was higher, fiber digestion was not depressed. Because of increased total intake (forage plus supplement) and increased digestion in Experiment 2, total digestible organic matter intake was greater in the supplemented animals, with little difference among carbohydrate sources.

Effects of supplemental degradable intake protein on intake and digestibility of bermuda hay (1998)

A study with 16 ruminally fistulated beef steers fed Bermuda hay ad libitum showed that the intake and digestibility of hay was not influenced by increasing levels of supplemental degradable intake protein (DIP). However, the hay used in this study was of medium quality; lower quality Bermuda hay with lower CP may respond to supplemental DIP.

Impact of increasing amounts of supplemental high-protein soybean meal on performance of range beef cows (1998)

One hundred and twenty spring-calving Hereford x Angus cows grazing low-quality, tallgrass-prairie forage were fed 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, or 6.0 lb soybean meal (SBM) per head daily. SBM as a source of supplemental degradable intake protein (DIP) can be effective in maintaining cow body weight and body condition during the winter grazing season. Performance as measured by changes in body weight and condition score was maximized when cows received approximately 3.5 to 3.8 lb/day. Below this level, cows lost about 48 lb (about .4 units of BCS) for every 1 lb decrease in the amount of supplemental SBM. The effect of amount of supplemental SBM on calf performance was minimal.

Effects of supplemental degradable intake protein on intake and digestibility of low-quality brome hay (1998)

The effects of increasing levels of degradable weight and assigned to one of four increasing intake protein (DIP) on intake and digestion of levels of DIP. Each steer was offered brome hay low-quality brome hay were evaluated using 16 at 130% of the average voluntary intake for the ruminally fistulated beef steers. Trends were preceding 5-day period. Supplemental DIP evident for small, positive changes in total intake (sodium caseinate; 91.6% CP, 100% DIP) was and digestion with increasing level of DIP ruminally infused at 7:00 AM, immediately prior supplementation. As a result, total digestible to feeding forage to provide .041, .082, and OM intake (TDOMI) increased with DIP .124% BW/day; controls received none. The supplement-ation but tended to plateau below forage contained 65.4% NDF and 5.9% CP, of the highest supplementation level. which 49% was DIP. DIP was estimated using

Effect of increasing proportion of supplemental nitrogen from urea on intake and utilization of low-quality, tallgrass-prairie forage by beef steers.

Five Angus x Hereford steers with ruminal and duodenal fistulas were used in a 5 x 5 Latin square to determine effects of increasing the proportion of urea in supplemental degradable intake protein (DIP) on intake, fermentation, and digestion. Steers had ad libitum access to low-quality, tallgrass-prairie forage (2.4% CP, 76% NDF). Supplemental DIP (380 g/d) was from sodium caseinate and(or) urea and was balanced with cornstarch to provide a final supplement (approximately 939 g DM/d) that contained 40% CP. The percentages of supplemental DIP from urea were 0, 25, 50, 75, and 100%. Intake of forage OM was not affected (P > or = .30) by urea level. Ruminal and total tract digestibilities of OM and NDF generally responded in a quadratic manner (P < or = .09) to increasing urea, with the lowest values observed at the highest urea level. As a result, digestible OM intake (DOMI) declined (linear, P = .03) with increasing proportions of urea and tended (quadratic, P = .14) to exhibit the largest proportional decline at the highest urea level. The effects of increasing urea on duodenal N flow, microbial efficiency, ruminal contents, and fluid dilution rate were minimal. Ruminal ammonia N and molar percent acetate increased linearly (P < or = .02), whereas most other VFA (except propionate) decreased (P < or = .05) with increasing urea. In conclusion, although forage OM intake was not altered, OM digestion, NDF digestion, and DOMI were lowest when all supplemental DIP was supplied as urea. Changes in fermentation characteristics reflected the change in source of available nitrogen.

Effects of various supplemental starch and protein levels on ruminal fermentation and liquid passage of beef steers fed tallgrass-prairie hay (1997)

The effect of supplements containing various proportions of degradable intake protein (DIP) and starch on ruminal digestion characteristics of forage-fed beef steers was evaluated. Fluid passage rates, ruminal ammonia (N H), 3 and total volatile fatty acid (VFA) concentrations increased as the amount of supplemental DIP increased. Starch infused at .3% of BW increased molar proportion s of propionate and butyrate and decreased acetate, compared to feeding DIP alone. However, proportions of branched-chain VFA increased with DIP at all levels of starch infusion. Total digestible organic matter intake (TDOMI) was increased with each addition of DIP; however, infusing starch within a DIP level decreased TDOMI. Providing supplemental DIP is more important for improving the use of low-quality, tallgrass-prairie hay than is ruminally available starch.

Effects of supplemental degradable intake protein on intake and digestibility of forage sorghum hay (1997)

Effects of supplemental degradable intake protein on intake and digestibility of forage sorghum hay (1997)