Effects of buffer or DL-methionine with different amounts of supplemental corn on feed intake and nutrient digestion by Holstein steers consuming bermudagrass hay

Two latin squares were conducted to determine the effects on feed intake and nutrient digestion of adding a ruminal buffer or DL-methionine to supplemental ground corn for Holstein steers (avg BW of 286 and 222 kg in Exp. 1 and 2, respectively) with ad libitum access to bermudagrass hay. In Exp. 1, steers were not supplemented (control) or were given .5 (LC) or 1.0% BW/d (HC) of ground corn without or with .021% BW of sodium bicarbonate (B). Total DMI was 2.39, 2.71, 2.79, 2.81 and 2.98% BW (effects of supplementation [P less than .05], level of corn [P less than .05] and buffer [P less than .06]), and OM digested was 3.56, 4.65, 4.65, 4.96 and 5.34 kg/d for control, LC, LCB, HC and HCB, respectively (effects of supplementation and corn level, P less than .05). In Exp. 2, corn levels were .24 and .74% BW/d and .0022% BW of DL-methionine (M) replaced B. Total DMI was 2.85, 3.00, 2.99, 3.22 and 3.34% BW (effects of supplementation and corn level, P less than .05), and digestible OM intake was 3.78, 4.24, 4.30, 4.84 and 5.12 kg/d for control, LC, LCM, HC and HCM, respectively (effects of supplementation and corn level, P less than .05). Overall, changes in feed intake and digestion with additions of a ruminal buffer and DL-methionine to corn supplements were not marked; however, buffer addition increased DMI intake to the greatest degree with 1.0% BW/d of corn.     

Relationships of body weight, forage composition, and corn supplementation to feed intake and digestion by Holstein steer calves consuming bermudagrass hay ad libitum

Holstein steer calves (101 to 350 kg BW) consumed bermudagrass hay ad libitum without or with supplemental ground corn up to 1.0% of BW. As BW increased, total DMI increased quadratically (-2.459 + .05448 [BW]-.000073 [BW2] + .540 [corn DMI]; R2 = .83, sy.x = .655). Each kilogram of corn DM decreased bermudagrass DMI by .46 kg. Total digestible OM intake (kg) increased with BW and corn supplementation (.314 + .0127 [BW] + .441 [corn OM intake]; R2 = .79, sy.x = .444). Feed intake level accounted for approximately 2.5 times more variability in total digestible OM intake than digestion did. Corn supplementation decreased digestion of bermudagrass NDF (62.50 - 8.468 [corn DMI, % BW]; R2 = .13, sy.x = 8.121), with a similar decrease across BW. Increasing bermudagrass DMI (% of BW) decreased bermudagrass NDF digestion slightly, but variation accounted for was only 33% of that attributable to corn DMI (% of BW). Concentrations of common fiber fractions (NDF, ADF, cellulose, hemicellulose, and ADL) in bermudagrass explained very little variation in feed intake and digestion, indicating considerable influence of other factors. Bermudagrass intake and digestion were not related, and no substantial interactions were observed among steer BW, corn level, and bermudagrass composition.     

Effects of supplemental silage on forage intake and utilization by steers grazing wheat pasture or bermudagrass

Seven trials were conducted to determine the effects of increasing amounts of silage (corn, wheat or sorghum) on forage intake, gastrointestinal tract fill, fecal output and ruminal flow and degradation of forage by cattle grazing wheat pasture or bermudagrass. In each of 3 yr, 24 steers grazed a common wheat or bermudagrass pasture and were randomly allocated to four treatments (0, .35, .70 or 1.05 kg silage DM.100 kg body weight-1.d-1). Intake and ruminal flow of forage were measured by feeding a single pulse dose of Yb-labeled forage followed by collection of fecal samples for 4 to 5 d and fitting Yb concentrations to a one-compartment, age-dependent model. Ruminal digestion kinetics of wheat forage were estimated in situ using eight ruminally cannulated steers fed 0 or .55 kg sorghum silage DM.100 kg body weight-1.d-1. Supplemental silage decreased wheat forage (P less than .10) and bermudagrass (P less than .01) intake linearly. However, total forage intake of bermudagrass plus silage increased linearly (P less than .05). Each kilogram of added silage DM decreased DM intake of wheat forage by .66 +/- .25 and of bermudagrass by .63 +/- .17 kg. Flow and turnover of wheat forage or bermudagrass were not altered (P greater than .15) by supplemental silage. Silage consumption increased extent of ruminal degradation of wheat forage DM (P less than .05; 63.1 vs 52.5%), indicating a positive associative effect of silage on wheat forage utilization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of supplemental Bermuda grass hay or corn on intake, digestion and performance of cattle consuming endophyte-infected fescue

Effects of supplemental Bermuda grass hay (BG) or ground corn on intake, digestion and performance of cattle consuming endophyte-infected fescue (I) were studied. In Exp. 1, a Latin square study, five growing Holstein steers (158.1 kg) consumed I ad libitum and were offered 0, .3, .6, .9 or 1.2% body weight (BW) of BG daily. Total dry matter (DM) intake rose linearly (P less than .05) with increasing BG, although intake was numerically similar with .6, .9 and 1.2% BW of BG. Digestibility was constant with diet (P greater than .10). Six growing Holstein steers used in Exp. 2, a Latin square with a 2 x 3 factorial arrangement of treatments, ingested I or noninfected (NI) fescue hay ad libitum with 0, .5 or 1.0% BW of ground corn. Total DM intake increased linearly as the level of corn rose (P less than .05). Total intake with I increased more with the first than with the second addition of corn, and the opposite occurred with NI (interaction between fescue infection and the quadratic effect of corn level, P less than .10). Organic matter digested (g/d) was greater for NI than for I and rose linearly with increasing corn ingestion (P less than .05). Ninety-six crossbred beef heifers and steers (184.2 kg avg initial live weight) were used in a 77-d fall grazing experiment (Exp. 3) with a 2 x 3 factorial treatment arrangement. Cattle grazed I or NI paddocks and were given no supplement or .34% BW of BG or .65% BW of ground corn on a daily basis (DM).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of supplemental alfalfa hay on the digestion of soybean hull-based diets by cattle

We evaluated the optimal level of alfalfa inclusion in soybean hull-based diets. In Exp. 1, 20 Holstein steers (319 kg of BW) were used in a complete block design. Treatments included a soybean hull mix (95.7% soybean hulls, 3% molasses, 0.5% urea, 0.8% mineral mix; DM basis) fed alone (100:0) or with 10.4, 20.7, or 30.9% (DM basis) coarsely chopped alfalfa hay (90:10, 80:20, and 70:30, respectively) or alfalfa alone (0:100). Diets were fed once daily at 1.75% (DM basis) of BW. In some cases, orts were present, which caused DM, OM, and NDF intakes to decrease (linear, P < 0.05) as alfalfa was added to the diets. Digestibilities of DM, OM, and NDF decreased linearly (P < 0.05) as alfalfa was added to the diets, but quadratic responses (P < 0.05) indicated that positive associative effects occurred between soybean hulls and alfalfa. Liquid dilution rates increased (linear, P < 0.05) with alfalfa additions to the diets and also demonstrated positive associative effects between soybean hulls and alfalfa (quadratic, P < 0.05). Solid passage rates were similar for 100:0 and 0:100 but were increased (quadratically and cubically, P < 0.05) when combinations of soybean hulls and alfalfa were fed. In Exp. 2, in vitro NDF digestibilities were measured for soybean hulls, alfalfa, and a blend of 85% soybean hulls and 15% alfalfa, each with no N source or supplemented with casein or urea to ascertain the effects of protein from alfalfa on digestibility. Disappearances were increased (P < 0.05) by addition of urea or casein, but no interactions between substrate and N supplement were observed. Addition of 30% alfalfa to diets consisting primarily of soybean hulls led to positive associative effects on diet digestibility, but alfalfa additions led to increased liquid and solid passage rates, suggesting that the benefit was not a result of slower passage of soybean hulls from the rumen.     

Net absorption and oxygen consumption by Holstein steers fed alfalfa or orchardgrass silage at two equalized intakes

The objective of this experiment was to compare net nutrient absorption and oxygen consumption by portal-drained viscera (PDV) of catheterized Holstein steers (333 kg) when fed alfalfa or orchardgrass silage at two equalized intakes. The design was a 4 X 4 Latin square with a 2 X 2 factorial arrangement of alfalfa or orchardgrass fed at 65 or 90 g dry matter/kg.75 live weight daily. Blood flow through PDV (dilution of p-aminohippurate), net nutrient absorption and oxygen consumption (venoarterial concentration differences times blood flow) were measured hourly for 12 h, followed by measurement of N and energy balance over 7 d. Compared with orchardgrass, steers when fed alfalfa absorbed more NH3-N (P less than .05), branched-chain volatile fatty acids (P less than .10) and n-valerate (P less than .05). Silage type did not affect (P greater than .10) blood flow to or O2 consumption by PDV or net absorption of glucose, L-lactate, acetate, propionate, urea-N, alpha-amino N or most amino acids. Oxygen consumption by PDV as a percentage of whole-animal O2 consumption was not different (P greater than .10) for steers when fed orchardgrass (27.2) or when fed alfalfa (23.6). Interrelationships between N and energy metabolism were responsible for the increased (P less than .05) metabolizable energy/kilogram silage dry matter and increased (P = .10) N retention by steers when fed alfalfa compared with orchardgrass. The PDV accounted for a substantial portion of whole-animal O2 consumption.     

Digestion, feed intake, and live weight gain by cattle consuming bermudagrass hay supplemented with whey.

Three experiments were conducted with cattle consuming bermudagrass hay to determine whether low-level supplements of whey alone, corn alone, or whey plus corn affect feed intake, digestion, and(or) BW gain. Six ruminally and duodenally cannulated beef cows (574 kg), used in a Latin-square trial (Exp. 1), were fed bermudagrass hay without supplementation (control) or with 2.8% whey (low whey, LW), 5.6% whey (high whey, HW), 17.4% ground corn (C), 2.8% whey plus 14.9% corn (C-LW), or 5.6% whey plus 12.4% corn (C-HW). Supplementing with whey and(or) corn increased ruminal butyrate (8.8, 9.4, 10.0, 9.6, 10.5, and 11.0 mol/100 mol of total VFA for control, LW, HW, C, C-LW, and C-HW, respectively; SE = .20). Supplements did not affect microbial N flow at the duodenum. Six Holstein steer calves (158 kg) in a Latin square (Exp. 2) consumed bermudagrass hay ad libitum alone (control) or with .075 or .15% BW whey (LW and HW, respectively), .5% BW ground corn (C), or corn-whey mixes made by substituting whey for corn (C-LW and C-HW). Substituting .15% BW of whey for corn increased (P less than .05) total OM intake slightly (3.99, 3.84, 3.75, 4.11, 4.28, and 4.47 kg for control, LW, HW, C, C-LW, and C-HW, respectively; SE = .10). In an 84-d randomized block experiment (Exp. 3), 96 beef calves (194 kg) consumed (ad libitum) low-quality bermudagrass hay alone or with C, LW, HW, C-LW, or C-HW supplements.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of frequency of offering and type of supplemental forage on intake and digestion in calves consuming endophyte-infected fescue hay

Two experiments were conducted to determine the effects of frequency of offering and type of supplemental forage on intake and digestion in calves consuming endophyte-infected fescue hay (I). In Exp. 1, five Holstein steers, averaging 128 kg body weight (BW), were used in a 5 X 5 Latin square experiment. All steers were given free access to I in the afternoon. Morning meals consisted of 1) ad libitum access to I daily (control), 2) .5% BW of Bermuda-grass hay (BG) daily, 3) 1.0% BW of BG every 2nd d, 4) 1.5% BW of BG every 3rd d and 5) 2.0% BW of BG every 4th d. Steers receiving BG consumed less (P less than .01) I and more (P less than .01) total dry matter (DM) than did steers given I alone. Within treatment, I intake was similar (P greater than .10) among days of the feeding cycle without BG. Organic matter (OM) digestion was lower (P less than .05) with than without BG. In Exp. 2, 12 beef calves (Angus and Hereford X Angus; 6 mo of age, 155 kg initial BW) were used in a completely randomized-design experiment. Calves were given ad libitum access to I daily (control) or to BG or wheat hay (WH) on d 1 and I the following 3 d. Hay (I, BG or WH) intake d 1 of the feeding cycle was higher for BG and WH than for the control treatment (16 and 45%, respectively) and higher for WH than BG (25%; P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Utilization of nitrogen and energy by Holstein steers fed formaldehyde- and formic acid-treated alfalfa or orchardgrass silage at two intakes

Our objective was to measure the utilization of energy (E) and N by Holstein steers when fed alfalfa and orchardgrass silages offered at 65 and 90 g DM/kg live weight (LW).75 daily. Twelve steers adapted to the Beltsville respiration chambers were assigned to three Latin squares with 42-d periods. Steers in one square had permanent catheters in the portal and two mesenteric veins. Energy and N balance were measured during a 7-d collection of feces and urine that included a 3-d measurement of respiratory exchange. Energy and N variables were not different between catheterized and uncatheterized steers. Apparent digestibilities of DM, OM, CP, neutral detergent solubles and permanganate lignin were higher (P less than .01) and digestibilities of NDF and ADF, hemicellulose and cellulose were lower (P less than .01) for steers consuming alfalfa compared to orchardgrass silage. When fed alfalfa, steers' daily gross energy intake, DE, urine energy, ME, heat production and tissue energy retention were greater (P less than .01) and fecal energy losses were less (P less than .01) than when they were fed orchardgrass. Partial efficiency of ME use for tissue energy (TE) was greater (P less than .01) for steers when fed alfalfa (46.1%) than when fed orchardgrass (35.6%). Apparent ME (kcal/LW.75) required for maintenance of TE was similar for steers when fed alfalfa (133.9) and orchardgrass (131.2) silages. Nitrogen retention (g/d) was 48% greater (P less than .01) for steers when fed alfalfa (30.6) than when fed orchardgrass (20.7). This study demonstrates that steers used ME from alfalfa more efficiently for TE deposition than ME from orchardgrass.     

Feed intake and digestion by beef steers consuming and receiving ruminal insertions of prairie hay differing in level and particle size

A 5 X 5 Latin square design involving five cannulated beef steers (342 and 358 kg avg initial and final body weights, respectively) fed prairie hay (76.7% neutral detergent fiber, 5.7% acid detergent lignin and .85% N) was conducted to evaluate effects on feed intake and nutrient digestion of variations in physical characteristics of ruminal digesta achieved by ruminal insertion of different amounts of prairie hay differing in particle size. Steers were fed hay ad libitum in two equal meals (0800 and 2000). At 1200, four of the steers received manual, ruminal insertions of ground hay. Fine hay (F) was ground through a screen with 2-mm openings (.39 mm mean particle size), whereas coarse hay (C) was ground through a screen with 2.54-cm openings (4.46 mm mean particle size). Amounts of hay inserted were .2 (low, L) or .4% (high, H of initial body weight of individual steers. Ruminal hay insertions comprised 18% of total dry matter (DM) intake for L and 34 and 37% for HF and HC, respectively. Fed hay consumption decreased (P less than .05) with hay insertion and was lower for H than L; total DM intake was not influenced by treatment (P greater than .10). Ruminal NH3-N concentrations and ruminal organic matter digestion was greater (P less than .05) with ruminal hay insertion than without and with H than with L (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Voluntary intake, growth rate, and tissue retention by Holstein steers fed formaldehyde- and formic acid-treated alfalfa and orchardgrass silages.

Alfalfa and orchardgrass herbages of similar digestibility were harvested at early and late maturity from primary growth and conserved as direct-cut silage using formic acid and formaldehyde simultaneously. Major compositional differences between the silages were lower NDF (principally hemicellulose) and a greater N content in alfalfa than in orchardgrass. An initial group of eight steers was slaughtered with a mean BW of 222 kg, and each of the four silages was fed to comparable groups of eight Holstein steers. Ad libitum DMI per unit of metabolic BW for alfalfa silages was 128% of that for orchardgrass silages. The ADG of steers fed alfalfa silages was 132% of that of steers fed orchardgrass silages. Despite greater ad libitum intake, total gut fill, as a percentage of BW, on alfalfa silages was 77% of that on orchardgrass silages. Daily empty BW gain of steers fed alfalfa silages was 158% of that of steers fed orchardgrass silages. Daily energy retention of steers fed alfalfa silages was 180% of that of steers fed orchardgrass silages. Steers fed alfalfa silages retained 140% more protein than steers fed orchardgrass silages did, but steers fed alfalfa silages retained only 71% as much protein energy relative to their total energy retention compared with steers fed orchardgrass silages. Differences in composition of daily energy retained were almost totally a result of differences in the total daily energy retention. Late alfalfa silage produced a greater daily gain than orchardgrass silage cut 2 wk earlier because greater intake compensated for lower digestibility.     

Impacts of increasing amounts of supplemental soybean meal on intake and digestion by beef steers and performance by beef cows consuming low-quality tallgrass-prairie forage

Two experiments were conducted to evaluate the impacts of increasing levels of supplemental soybean meal (SBM) on intake, digestion, and performance of beef cattle consuming low-quality prairie forage. In Exp. 1, ruminally fistulated beef steers (n = 20; 369 kg) were assigned to one of five treatments: control (forage only) and .08, .16, .33, and .50% BW/d of supplemental SBM (DM basis). Prairie hay (5.3% CP; 49% DIP) was offered for ad libitum consumption. Forage OM intake (FOMI) and total OM intake (TOMI) were increased (cubic, P = .01) by level of supplemental SBM, but FOMI reached a plateau when the daily level of SBM supplementation reached .16% BW. The concomitant rises in TOMI and OM digestibility (quadratic, P = .02) resulted in an increase (cubic, P = .03) in total digestible OM intake (TDOMI). In Exp. 2, spring-calving Hereford x Angus cows (n = 120; BW = 518 kg; body condition [BC] = 5.3) grazing low-quality, tall-grass-prairie forage were assigned to one of three pastures and one of eight treatments. The supplemental SBM (DM basis) was fed at .08, .12, .16, .20, .24, .32, .40, and .48% BW/d from December 2, 1996, until February 10, 1997 (beginning of the calving season). Performance seemed to reach a plateau when cows received SBM at approximately .30% BW/d. Below this level, cows lost approximately .5 unit of BC for every .1% BW decrease in the amount of supplemental SBM fed. Providing supplemental SBM is an effective means of improving forage intake, digestion, and performance of beef cattle consuming low-quality forages.     

Effect of method of applying fibrolytic enzymes or ammonia to Bermudagrass hay on feed intake, digestion, and growth of beef steers

This study examined how different methods of applying a fibrolytic enzyme or ammonia affect the nutritive value of Bermudagrass hay and the performance of beef cattle. Fifty Angus x Brangus crossbred steers (mean initial BW 244 +/- 26 kg) were individually fed for ad libitum intake of a 5-wk regrowth of a mixture of Florakirk and Tifton 44 Bermudagrass [Cynodon dactylon (L.) Pers] hay for 84 d with a concentrate supplement (77% soybean hull pellets, 23% cottonseed meal (DM basis) fed at 1% of BW daily. The Bermudagrass was conserved as hay without treatment (control), with NH(3) (30 g/kg of DM), or with a fibrolytic enzyme (16.5 g/t, air-dry basis) that was applied immediately after cutting (Ec), at baling (Eb), or at feeding. Chromic oxide was dosed to steers for 10 consecutive days, and fecal Cr concentrations from the last 5 d were used to estimate apparent total tract digestibility. In situ ruminal DM degradability was measured by incubating ground (4-mm) hay samples in duplicate in each of 2 ruminally cannulated cows having ad libitum access to Bermudagrass hay and 500 g/d of soybean meal. Unlike the enzyme treatment, ammoniation increased (P < 0.001) the CP concentration and reduced (P < 0.001) NDF, hemicellulose, and lignin concentrations of hay. Total DMI was greater (P < 0.05) for steers fed hays treated with Ec or NH(3) than for those fed control hays. All additive treatments increased (P < 0.05) DM digestibility, and NH(3), Ec, and Eb treatments also increased (P < 0.01) NDF digestibility. The initial and final BW, ADG, BCS, G:F, and hip height of the steers were not affected (P > 0.05) by treatment. The wash loss fractions in hays treated with Ec and Eb were lower than that in the control hay, but the potentially degradable fraction, total degradable fraction, and the effective degradability were increased (P < 0.01) by NH(3) treatment. Application at cutting was the most promising method of enzyme treatment, and this treatment was almost as effective as ammonia for enhancing forage quality.     

Effects of base ingredient in cooked molasses blocks on intake and digestion of prairie hay by beef steers

Twelve steers (332 kg) were used in three simultaneous 4 x 3 incomplete Latin squares to evaluate effects of beet molasses (BEET), cane molasses (CANE), or concentrated separator by-product (CSB) as base ingredients in cooked molasses blocks on intake and digestion of prairie hay and ruminal characteristics. All steers had ad libitum access to prairie hay (5.9% CP and 69.4% NDF; DM basis). The four experimental treatments included a control (no supplement) and three cooked molasses blocks, based on BEET, CANE, or CSB, fed daily at .125% of BW (.42 kg/d as-fed, .13 kg/d CP). Forage OM, NDF, and N intakes; digestible OM, NDF, and N intakes; and total tract OM and N digestibilities (percentage of intake) were greater (P < .05) for steers fed cooked molasses blocks than for control steers. Total tract OM digestibility was greater (P < or = .06) for steers fed BEET blocks (54.0%) than for those fed CSB (52.1%) or CANE blocks (52.2%). Digestion of NDF was greatest (P < .05) for steers fed BEET blocks (51.9%) and tended to be greater (P < .07) for steers fed CANE (49.3%) or CSB blocks (49.3%) than for control steers (46.9%). Ruminal ammonia concentrations were greater (P < .05) for steers fed cooked molasses blocks (.89 mM) than for control steers (.21 mM); this was primarily due to increases to 4.6 mM at 2 h postfeeding for steers fed blocks. Concentrations of total VFA in ruminal fluid were greater (P < .05) for steers fed BEET (92.7 mM) and CSB (88.1 mM) blocks than for control steers (80.3 mM), whereas concentrations for steers fed CANE blocks were intermediate (85.4 mM). Steers supplemented with cooked molasses blocks had greater molar percentages of butyrate than did control steers, particularly shortly after feeding. In summary, supplementation with cooked molasses blocks increased forage intake and digestion. The three base ingredients elicited similar responses, although steers fed BEET had slightly greater OM and NDF digestibilities than those fed CANE or CSB.     

Sites of digestion in beef steers fed bermudagrass hay and supplemented with high-nitrogen feeds alone or mixed with tallow

Five crossbred beef steers (329 kg) were used in a 5 x 5 Latin square experiment with 14-d periods to determine the effects of supplementation with high-nitrogen (N) feeds alone or mixed with tallow on sites of digestion with a basal diet of bermudagrass hay. Hay was 1.93% nitrogen, 75% neutral detergent fibre and fed at 1.83% of body weight (dry matter; DM). Supplements were basal (B; 105 g DM): 81.8% dried molasses product (DMP) and 18.2% calcium carbonate (CC); soybean meal (S; 942 g DM): 88.0% soybean meal, 9.8% DMP and 2.2% CC; S mixed with 9.8% tallow (SF; 1041 g DM); corn gluten and blood meals (CB; 662 g DM): 62.5% corn gluten meal, 20.8% blood meal, 13.6% DMP and 3.0% CC; CB mixed with 13.2% tallow (CBF; 757 g DM). Total N intake was 117, 185, 187, 174 and 172 g/d, and duodenal N flow was 121, 148, 143, 162 and 169 g/d for B, S, SF, CB and CBF, respectively, being lower for B than for other treatments and higher for supplements with the corn gluten and blood meal mix than for soybean meal (P less than 0.05). Duodenal microbial N flow was 39, 51, 49, 38 and 45 g/d for B, S, SF, CB and CBF, respectively, being greater (P less than 0.05) for supplements with soybean meal than with corn gluten and blood meals. Duodenal flow of feed N was greater (P less than 0.05) with than without high-N feeds and for supplemental corn gluten and blood meals than for soybean meal (78, 90, 86, 117 and 116 g/d for B, S, SF, CB and CBF, respectively). In conclusion, mixing of tallow and high-N feeds did not affect the extent of ruminal N disappearance, and soybean meal supplementation increased duodenal N flow less than did supplementation with corn gluten and blood meals. Increased duodenal N flow with soybean meal was associated with about equal elevations of ruminal outflow of microbial and feed N, whereas the corn gluten-blood meal mix affected the intestinal protein supply by increasing ruminal escape of feed protein.     

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.     

Effects of cottonseed meal supplementation time on ruminal fermentation and forage intake by Holstein steers fed fescue hay.

Four ruminally cannulated Holstein steers (average BW 303 kg) were used in a 4 x 4 Latin square design digestion trial to study the influence of daily cottonseed meal (CSM; 1.6 g of CP/kg of BW) supplementation time on forage intake and ruminal fluid kinetics and fermentation. Steers were housed individually in tie stalls and were fed chopped fescue hay on an ad libitum basis at 0600 and 1400. Treatments were 1) control, grass hay only (CON) and grass hay and CSM fed once daily at 2) 0600 (EAM) 3) 1000 (MAM), or 4) 1400 (PM). Ruminal NH3 N concentrations reflected a time of supplementation x sampling time interaction (P less than .05); CON steers had the lowest (P less than .05) ruminal NH3 N concentrations at all times other than at 0600, 1000, 1200, and 2400, when they did not differ (P greater than .05) from at least one of the supplemented groups. Forage intake, ratio of bacterial purine:N, rate of DM and NDF disappearance, and ruminal fluid kinetics were not influenced (P greater than .05) by supplementation time. Total ruminal VFA differed (P less than .05) between CON and supplemented steers, as well as among supplemented steers (linear and quadratic effects P less than .05). Acetate, propionate, and valerate proportions were influenced (P less than .05) by a sampling time X supplementation time interaction. Under the conditions of this study, greater peak ammonia concentrations with morning supplementation than with afternoon supplementation did not stimulate ruminal fermentation or rate of NDF disappearance.     

Effects of dietary alfalfa:orchardgrass hay and lasalocid on nutrient utilization by gravid sows

Twenty-four third- and fourth-parity crossbred gravid sows were housed in metabolism stalls and randomly allotted to four dietary treatments: corn-alfalfa:orchardgrass hay (46%; CH), CH plus lasalocid (CHL), corn-soybean meal (CS) or CS plus lasalocid (CSL). Daily feed intake was 2.36 kg for CH- and CHL-fed sows and 1.66 kg for CS- and CSL-fed sows. Lasalocid intake was 110 mg X sow-1 X d-1. Total feces and urine were collected during two 5-d collection periods, 40 and 80 d postcoitum. Digestible energy (DE), metabolizable energy (ME), nitrogen (N) retention, dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibilities, and retention of calcium (Ca), total phosphorus (P), magnesium (Mg), sodium (Na) and potassium (K) were determined. Percentage DE and ME were greater (P less than .0001) for CS- and CSL-fed sows (88.3 and 83.4%) than for CH- and CHL-fed sows (65.2 and 61.3%). Lasalocid did not influence (P greater than .05) DE and ME values but decreased (P less than .01) the ME:DE ratio. Percentage N digestibility was greater (P less than .0001) for CS- and CSL-fed sows (85.7%) than for CH- and CHL-fed sows (60.8%), but there was no significant difference in N retention, expressed as a percentage of N intake. Lasalocid increased (P less than .03) percentage N digestibility; however, the diet X additive interaction decreased (P less than .005) grams N retained X sow-1 X d-1 for CSL-fed sows. The CH- and CHL-fed sows digested more grams of DM, NDF and ADF but had lower percentage digestibilities of DM and fiber fractions than did CS- and CSL-fed sows. The diet X additive interaction decreased (P less than .05) percentages of Ca, P and K digested and decreased (P less than .05) grams mineral retained (Ca, P, Mg and K) and mineral retained expressed as a percentage of intake for CSL-fed sows. Results indicate that alfalfa:orchardgrass hay and lasalocid influenced energy, fiber, nitrogen and mineral utilization by gravid sows.     

Duodenal nutrient flow and digestibility in Holstein steers fed formaldehyde- and formic acid-treated alfalfa or orchardgrass silage at two intakes

Formaldehyde- and formic acid-treated alfalfa or orchardgrass silage were fed at 65 and 90 g DM/kg BW.75.d) to growing Holstein steers (209 +/- SE = 35 kg) fitted with permanent ruminal and duodenal cannulas in a 4 x 4 latin square. Alfalfa had higher (P less than .01) concentrations of cell solubles, total N and rumen-soluble N than did orchardgrass. Digestible energy (Mcal/d), total N and soluble N intake (g/d) were higher (P less than .05) for steers fed alfalfa than for those fed orchardgrass. Total duodenal OM, DM, NDF, N and non-NH3-N flows were greater (P less than .001) for steers fed alfalfa than for those fed orchardgrass and were greater (P less than .001) at high vs low intake. Duodenal bacterial N flow (g/d) was greater (P less than .001) for steers fed alfalfa than for those fed orchardgrass, and bacterial N synthesis (g/kg DM truly digested in the rumen) was 58 and 32, respectively (P less than .001). Ruminal concentrations of NH3-N (P less than .001) and VFA (P less than .05) were greater for steers fed alfalfa than for those fed orchardgrass. Total tract DM, energy and N digestibilities were higher (P less than .05) for steers fed alfalfa vs orchardgrass, whereas total tract NDF digestibility was lower (P less than .01). Tissue N retention tended to be greater (P less than .1) for steers fed alfalfa than for those fed orchardgrass. Regression analysis indicated that duodenal non-NH3-N flow was related to intake of metabolizable energy and soluble N (R2 = .939). Improved performance and higher efficiency of use of ME for tissue gain by steers fed alfalfa rather than orchardgrass is related to lower ruminal acetate:propionate, higher microbial efficiency and greater duodenal DM and N flows.     

Effects of supplementation on intake, digestion, and performance of beef cattle consuming fertilized, stockpiled bermudagrass forage

Experiments were conducted to determine the effects of increasing supplement protein concentration on performance and forage intake of beef cows and forage utilization of steers consuming stockpiled bermudagrass forage. Bermudagrass pastures were fertilized with 56 kg of N/ha in late August. Grazing was initiated during early November and continued through the end of January each year. Treatments for the cow performance trials were: no supplement or daily equivalents of 0.2, 0.4, and 0.6 g of supplemental protein per kilogram of BW. Supplements were formulated to be isocaloric, fed at the equivalent of 0.91 kg/d, and prorated for 4 d/wk feeding. Varying the concentration of soybean hulls and soybean meal in the supplements created incremental increases in protein. During yr 1, supplemented cows lost less weight and condition compared to unsupplemented animals (P < 0.05). During yr 2, supplemented cows gained more weight (P = 0.06) and lost less condition (P < 0.05) compared to unsupplemented cows. Increasing supplement protein concentration had no affect on cumulative cow weight change or cumulative body condition score change. Forage intake tended to increase (P = 0.13, yr 1 and P = 0.07, yr 2) in supplemented cows. Supplement protein concentration did not alter forage intake. In a digestion trial, four crossbred steers were used in a Latin square design to determine the effects of supplement protein concentration on intake and digestibility of hay harvested from stockpiled bermudagrass pasture. Treatments were no supplement; or 0.23, 0.46, and 0.69 g of supplemental protein per kilogram of BW. Forage intake increased (P < 0.05) 16% and OM intake increased (P < 0.01) 30% in supplemented compared to unsupplemented steers. Diet OM digestibility increased (P = 0.08) 14.5% and total digestible OM intake increased (P < 0.05) 49% in supplemented compared to unsupplemented steers. Supplement protein concentration did not alter forage intake, total digestible OM intake, or apparent digestibility of OM or NDF. During the initial 30 d after first killing frost, beef cows did not respond to supplementation. However, later in the winter, supplementation improved utilization of stockpiled bermudagrass forage.