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)     

Effects of supplemental alfalfa hay on feed intake and digestion by Holstein steers consuming high-quality bermudagrass or orchardgrass hay

Effects of level and frequency of supplementation with alfalfa (A) on feed intake and digestion by steers fed bermudagrass (B) or orchardgrass (O) were determined in two Latin square experiments. In Exp. 1, six Holstein steers (224 kg) were fed B (2.25% N; 71.4% NDF) or O (2.52% N; 64.3% NDF) with 0, 15 or 30% (DM) A (2.70% N; 44.0% NDF). Total DMI was 2.43, 2.72 and 2.85% BW for B and 2.98, 3.00 and 2.87% BW for O with 0, 15 and 30% A, respectively. Total DMI was affected by forage (P less than .05), A level (linear; P less than .06) and a forage x A level (linear) interaction (P less than .05). Digestible OM intake increased .42 (15%) and .67 kg (24%) with feeding of 15 and 30% A, respectively, for B, but for O, only dietary inclusion of 30% A elevated digestible OM intake (.14 kg and 4% increases). In Exp. 2, five Holstein steers (165 kg) were fed B (1.81% N; 78.6% NDF) alone or with A (2.76% N; 52.8% NDF). Morning meals consisted of ad libitum B (OA), .3% BW of A daily (.3A), .6% BW of A every 2nd d (.6A), .9% BW of A every 3rd d (.9A) or 1.2% BW of A every 4th d (1.2A). All steers received B in the afternoon ad libitum, and B was given in the morning when A was not fed. Total DMI was 2.31, 2.12, 2.12, 2.26 and 2.29% BW for OA, .3A, .6A, .9A and 1.2A, respectively (SE .049). Grass characteristics affected response in feed intake to legume supplementation. Frequency of dietary legume addition may alter feed intake.     

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.     

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.     

Intake and digestion in cattle fed warm- or cool-season grass hay with or without supplemental grain

Intake and digestion in cattle fed warm- or cool-season grass hay with or without low-level grain supplementation were studied with a 2 x 2 factorial arrangement of treatments in two 4 x 4 Latin square experiments. In Exp. 1, four cannulated beef cows (396 kg) were given Bermuda grass (B) or orchard grass (OG) hay at 1.5% body weight (BW) with 0 or .3% BW of ground corn (C; dry matter). Bermuda grass contained 12.1% crude protein, 79.3% neutral detergent fiber (NDF) and 5.5% acid detergent lignin (ADL); OG contained 10.6% crude protein, 82.4% NDF and 8.1% ADL. An interaction (P less than .07) between forage type and C supplementation was noted for microbial N entering the duodenum; C supplementation had a positive effect with B (30% increase) and little effect with OG. Corn supplementation did not affect ruminal NDF digestion with B, but it elicited an increase with OG (interaction, P less than .05; means were 60.7, 60.1, 61.5 and 66.3%). In the second experiment, growing dairy steers (196 kg) were given ad libitum access to similar B or OG hays and were fed 0 or .5% BW of C. Dry matter (DM) intake was lower for OG than for B (P less than .05) and was lower with than without C (P less than .06; means were 2.76, 2.56, 2.53 and 2.30% BW for B, BC, OG and OGC, respectively). Total tract organic matter digestion (%) was higher for OG than for B (P less than .10) and was higher with than without C (means were 54.7, 61.5, 60.4 and 65.3%). In conclusion, chemical constituents such as NDF may govern differences in intake between warm- and cool-season grasses, but physical attributes of the forages appear more important to digestion.     

Voluntary intake and digestion of Coastal Bermuda grass hay by yearling and mature horses

Coastal Bermuda grass hay was fed as the sole source of nutrients to determine comparative voluntary intake and nutrient digestibility of hay in yearling and mature horses. Yearling horses consumed dry matter at a higher (P<.10) percentage of their body weight (2.5%) than mature horses (2.0%). digestion of hemicellulose was higher (P<.05) in mature horses, but digestion of dry matter, gross energy, neutral detergent fiber and crude protein was similar between the 2 classes of horses.     

Intake, digestion, and N metabolism in steers fed endophyte-free, ergot alkaloid-producing endophyte-infected, or nonergot alkaloid-producing endophyte-infected fescue hay

A digestion and N balance trial was conducted to compare effects of traditional endophyte-infected (E+), endophyte-free (E-), and nontoxic endophyte infected (NE; MaxQ; Pennington Seed, Inc., Madison, GA) Jesup tall fescue (Festuca arundinacea Schreb.) hay on digestion and N retention in steers. Hay composition (DM basis) was as follows: E+ (10.8% CP, 59.9% NDF, and 29.4% ADF), E- (11.8% CP, 58.5% NDF, and 28.4% ADF), and NE (11.6% CP, 58.6% NDF, and 28.3% ADF). Eight Polled Hereford steers (initial BW 240 +/- 9 kg) were used in a replicated, 3 x 3 Latin square design, with an extra steer allotted to each square. Steers were fed ad libitum for 14 d, followed by a 9-d adaptation to restricted intake (based on the animal with the lowest ad libitum intake for the square) and a 5-d fecal and urine collection. Water intake (20.2 L/d) and urine output (7.40 L/d) did not differ (P > 0.10) during the collection period. Plasma prolactin concentration was less (P < 0.05) for steers on the E+ hay (8.83 ng/mL) than for those on the E- hay (18.03 ng/mL) and intermediate for steers on the NE hay (12.65 ng/mL). Endophyte-infected hay differed (P < 0.05) from E- and NE in ad libitum DMI (5.02 vs. 5.62 and 5.61 kg/d, respectively) and ad libitum DMI as a percentage of BW (1.86 vs. 2.06 and 2.06%, respectively). Restricted DMI during the fecal and urine collection was lower (P < 0.05) for E+ hay than for E- (5.04 vs. 5.24 kg/d), and NE was intermediate (5.19 kg/d). Dry matter digestibility was lower (P < 0.05) for E+ compared with E- and NE (62.3 vs. 67.0 and 65.9%, respectively). Digestibility of ADF was lower (P < 0.05) for E+ than for E-, and was intermediate for NE (61.5, 66.0, and 63.9%, respectively). There were no differences for NDF, cellulose, or hemicellulose digestibilities among hay types. Crude protein digestibility was higher (P < 0.05) for E- and NE than for E+ (54.3 and 52.5 vs. 48.1%, respectively). Nitrogen retention was lower (P < 0.01) for E+ than for E- or NE (15.6 vs. 22.7 or 23.0 g/d, respectively). Hay type did not influence plasma urea N, urine urea N output, or urine urea N as a percentage of urinary N. Results from this study indicate that E+ tall fescue hay was lower in ad libitum DMI, DM digestibility, and N retention than NE or E- hays with similar chemical composition. Hay from NE and E- fescue had nearly identical composition, and did not differ for any variable measured.     

Effects of offering different amounts and types of supplemental feeds to growing dairy steers fed endophyte-infected fescue hay ad libitum on intake, digestion, passage rate and serum prolactin concentration

Ten Holstein steers (141 kg) were used in two 5 X 5 Latin-square experiments conducted simultaneously to determine the effects of offering different levels and types of feeds with endophyte-infected fescue given ad libitum. In Exp. 1, steers were given ad libitum access to infected fescue hay in the afternoon; in the morning fescue was given ad libitum (basal) or bermudagrass or clover hays were fed at .5 or 1.0% of body weight (BW). Supplementation did not affect total dry matter intake (P greater than .10), but supplementation at 1.0% of BW yielded total intake greater than supplementation at .5% of BW (P less than .05). Supplementation did not change digestibilities of dry or organic matter (P greater than .10). Particulate passage rate was greater (P less than .10) with supplementation at 1.0 than at .5% of BW, and increasing the level of supplementation from .5 to 1.0% of BW affected fluid passage rate positively with clover but negatively with bermudagrass (interaction, P less than .05). Serum prolactin increased (P less than .05) with all supplementation treatments, although no differences were observed between supplement type-supplementation level combinations (P greater than .10). Ground corn and wheat hay were supplements in Exp. 2. Total intake of dry matter was greater with supplements provided at 1.0 rather than at .5% of BW and for corn rather than wheat hay (P less than .05). Neutral detergent fiber digestion (percent of intake and grams per day) rose when wheat hay was offered at 1.0 vs .5% of BW but declined when the level of supplemental corn increased from .5 to 1.0% of BW (interaction, P less than .05). There were no differences among diets in particulate and fluid passage rates and serum prolactin concentration. Supplementation with nontoxic forage of a basal diet of infected fescue yielded intake substitution when forage was offered at .5% of BW, although incomplete substitution occurred with 1.0% of BW of supplemental forage such that total intake increased as compared to the lower level of supplementation.     

Influence of level of supplemental whole flaxseed on forage intake and site and extent of digestion in beef heifers consuming native grass hay

The objectives of this study were to evaluate the influence of supplemental whole flaxseed level on intake and site and extent of digestion in beef cattle consuming native grass hay. Nine Angus heifers (303 +/- 6.7 kg of BW) fitted with ruminal and duodenal cannulas were used in a triplicated 3 x 3 Latin square. Cattle were given ad libitum access to chopped native grass hay (9.6% CP and 77.5% NDF, OM basis). All animals were randomly allotted to 1 of 3 experimental treatments of hay plus no supplement (control); 0.91 kg/d whole flaxseed (23.0% CP, 36.3% NDF, and 25.5% total fatty acid, OM basis); or 1.82 kg/d whole flaxseed on a DM basis. Supplemental flaxseed tended to decrease (linear, P = 0.06) forage OM intake. However, total OM intake did not differ (P = 0.29) with increasing levels of flaxseed. Total duodenal OM flow increased (linear, P = 0.05) with additional flaxseed in the diet, and no differences (P = 0.29) were observed for microbial OM flow. True ruminal OM disappearance was not affected (P = 0.14) by supplemental flaxseed. Apparent lower tract OM digestibility increased (linear, P = 0.01) with level of whole flaxseed. Apparent total tract OM digestibility was not different (P = 0.41) among treatments. Nitrogen intake increased (linear, P < 0.001) with supplemental flaxseed. In addition, total duodenal N flow tended (P = 0.08) to increase with additional dietary flaxseed. However, true ruminal N digestibility did not differ (P = 0.11) across treatment. Supplemental whole flaxseed did not influence ruminal (P = 0.13) or total tract (P = 0.23) NDF digestibility. Ruminal molar proportion of propionate responded quadratically (P < 0.001) with increasing levels of whole flaxseed. An increase in the duodenal supply of 18:3n-3 (P < 0.001), total unsaturated fatty acids (P < 0.001), and total fatty acids (P < 0.001) was observed with additional dietary whole flaxseed. Apparent postruminal 18:3n-3 disappearance tended to decrease (P = 0.07) as intake of flaxseed increased. Overall, the inclusion of 1.82 kg/d of flaxseed does not appear to negatively influence nutrient digestibility of a forage-based diet and therefore can be used as an effective supplement to increase intestinal supply of key fatty acids important to human health.     

Effects of corn gluten feed on forage intake, digestibility and ruminal parameters of cattle fed native grass hay

Thirty-two beef cows (467 kg) were individually fed native grass hay and supplement for two 14-d periods in each of 2 yr. Supplement treatments and amounts fed (kilograms/day) were negative control (NC), 0, or equal amounts of protein from soybean meal (SBM), .7; a blend of soybean meal and corn gluten feed (SBM/CGF), 1.0; or corn gluten feed (CGF) 1.6. Cows received supplement at 0645 and had ad libitum access to native grass hay from 0700 to 1130 and from 1530 to 2000. Compared with NC, all protein supplements increased (P less than .05) ruminal NH3, propionate and butyrate concentrations at 4 and 25 h postfeeding. Ruminal fluid pH, total VFA and acetate concentrations at 4 and 35 h postfeeding were not affected by supplements. All supplements increased (P less than .01) hay intake as well as hay, acid detergent fiber (ADF) and total diet dry matter (DM) digestibility. Compared to supplemental SBM, feeding CGF reduced (P less than .01) hay intake. Calculated daily intakes of metabolizable energy (ME) were 12, 17, 18, and 17 Mcal for NC, SBM, SBM/CGF and CGF, respectively. Hay intake, DM and ADF digestibility and ME intakes tended to be higher for SBM/CGF than for the average of SBM and CGF fed alone. Intakes of digestible DM and ADF were not altered by protein supplements, suggesting that intake responses were due to increased diet digestibility. Corn gluten feed appears to be an effective source of supplemental protein and energy for cows consuming low-quality roughage.     

Effects of supplemental zinc and manganese on ruminal fermentation, forage intake, and digestion by cattle fed prairie hay and urea

One in vitro and one in vivo metabolism experiment were conducted to examine the effects of supplemental Zn on ruminal parameters, digestion, and DMI by heifers fed low-quality prairie hay supplemented with urea. In Exp. 1, prairie hay was incubated in vitro for 24 h with five different concentrations of supplemental Zn (0, 5, 10, 15, and 20 ppm) and two concentrations of supplemental Mn (0 and 100 ppm), both provided as chloride salts. Added Mn increased (P < 0.02) IVDMD, but added Zn linearly decreased (P < 0.03) IVDMD. Added Zn tended to increase the amount of residual urea linearly (P < 0.06) at 120 min and quadratically (P < 0.02) at 180 min of incubation, although added Mn counteracted these effects of added Zn. Six 363-kg heifers in two simultaneous 3 x 3 Latin squares were fed prairie hay and dosed once daily via ruminal cannulas with urea (45 or 90 g/d) and with Zn chloride to provide the equivalent of an additional 30 (the dietary requirement), 250, or 470 ppm of dietary Zn. After a 7-d adaptation period, ruminal contents were sampled 2, 4, 6, 12, 18, 21, and 24 h after the supplement was dosed. Supplemental Zn did not alter prairie hay DMI (mean = 4.9 kg/d) or digestibility, although 470 ppm added Zn tended to decrease (P < 0.06) intake of digestible DM, primarily due to a trend for reduced digestibility with 470 ppm supplemental Zn. Zinc x time interactions were detected for both pH (P = 0.06) and NH3 (P = 0.06). At 2 h after dosing, ruminal pH and ruminal ammonia were linearly decreased (P < 0.05; P < 0.01) by added Zn. At 5 h after feeding, ruminal pH was linearly increased (P < 0.05) by added Zn, suggesting that added Zn delayed ammonia release from urea. The molar proportion of propionate in ruminal fluid was linearly and quadratically increased (P < 0.02; P < 0.01) whereas the acetate:propionate ratio was linearly and quadratically decreased (P = 0.02; P < 0.05) by added Zn. Through retarding ammonia release from urea and increasing the proportion of propionate in ruminal VFA, Zn supplementation at a concentration of 250 ppm may decrease the likelihood of urea toxicity and increase energetic efficiency of ruminal fermentation.     

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.     

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.     

Physiological responses of cattle consuming tall fescue to environmental temperature and supplemental phenothiazine

The influence of supplemental phenothiazine (P) on growth and physiological criteria was studied in parasite-controlled calves consuming endophyte (Acremonium coenophialum)-infected tall fescue (TF). In Exp. 1, nine Angus heifer calves (312 kg) were supplemented with 227 g corn-mineral (CM) mix twice daily and allowed ad libitum access to either high-endophyte (HE) G1-307 (greater than 90% infected) or low-endophyte (LE) Kenhy (less than 1% infected) tall fescue hay, or HE G1-307 plus 2 g/d P in the daily supplement. Calves were kept in temperature-controlled rooms for 12 d at 21 degrees C followed by 7 d at 34 degrees C. In Exp. 2, 48 Angus steer calves (312 kg) were assigned to treatment groups consisting of calves grazing HE Kentucky-31 (57% infected) or LE Johnstone (less than 1% infected) TF, and supplemented daily with either .91 kg of a control CM mix or .91 kg of the CM mix containing 2 g P. The 112-d experiment was initiated on May 4 with BW and rectal temperature (RT) measurements and blood collected at 28-d intervals. In both experiments, calves receiving HE TF had lower (P less than .01) serum prolactin concentrations (PRL) at elevated ambient temperature and lower (P less than .01) serum alkaline phosphatase activities (AP) but higher (P less than .01) RT than calves consuming LE TF regardless of ambient temperature.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of feeding endophyte-infected fescue hay on portal and hepatic nutrient flux in steers

Six Holstein steers (313 +/- 10 kg BW) surgically fitted with hepatic portal, mesenteric venous, mesenteric arterial, and hepatic venous catheters were used in a replicated crossover design experiment to evaluate the feeding of Acremonium coenophialum-infected fescue hay on portal-drained visceral and hepatic nutrient metabolism. Only four steers had functional hepatic catheters. Infected (INF) and endophyte-free (EF) fescue hays were harvested on the same day in May, at the soft dough stage of maturity, from a similar location in southeast Kansas. The hay was chopped through a 2.5-cm screen and fed in 12 portions daily. Intake was limited to 5.2 kg of DM/d to equalize consumption. Each experimental period lasted 21 d. Dietary CP concentration was greater for INF than for EF (9.9 vs 8.6%); however, apparent digestibilities of DM (52.6%) and N (37%) were not different. Ruminal total VFA concentrations and molar proportions were not different with the exception of butyrate, which was increased (P less than .10) for steers when they were fed INF. Feeding of INF increased (P less than .05) arterial beta-hydroxybutyrate concentration and decreased (P less than .10) arterial butyrate concentration. Steers fed EF showed a greater (P less than .05) portal-arterial concentration difference for acetate and an increased (P less than .05) net portal flux of acetate (500 vs 620 mmol/h). No differences in net flux were noted for any of the other VFA, glucose, lactate, urea N, insulin, glucagon, or prolactin.(ABSTRACT TRUNCATED AT 250 WORDS)     

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 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.     

Influence of ruminal or duodenal soybean oil infusion on intake, ruminal fermentation, site and extent of digestion, and microbial protein synthesis in beef heifers consuming grass hay.

Six heifers (two Hereford X Jersey, four Hereford X Longhorn; average BW 278 kg) cannulated at the rumen and duodenum and fed a grass hay (fescue/orchardgrass) diet were used in a replicated 3 X 3 Latin square. Treatments were either no infusion (C), 150 ml of duodenally infused soybean oil (DI), or 150 ml of ruminally infused soybean oil (RI)/heifer twice daily for a total daily infusion of 300 ml of soybean oil. Periods of the Latin square included 18 d for adaptation and 5 d for collection. Forage OM, ADF, NDF, and N intakes were not affected (P greater than .10) by soybean oil infusion. Ruminal (P = .11) and total tract (P less than .10) OM digestibilities were decreased by RI compared with C or DI, but ADF and NDF digestibilities were not affected by treatment. Duodenal N (P less than .05) and microbial N flows were increased (P less than .10) for C and RI compared with DI. Microbial efficiency (g of N/kg of OM truly fermented) was improved (P less than .10) by RI compared with DI but did not differ (P greater than .10) from C. Ruminal pH was lower (P less than .05) with RI than with either C or DI. Ruminal NH3 N, total VFA, and acetate were not affected (P greater than .10) by treatment. Propionate (mol/100 mol) was greater (P less than .05) with RI than with DI and C, but the proportion of butyrate did not differ among treatments. These data indicate minimal direct benefits for improving forage usage as a result of soybean oil infusion with a 100% grass diet; however, animals should realize benefits from additional dietary energy provided by infused lipid.     

Effects of increasing level of supplemental barley on forage intake, digestibility, and ruminal fermentation in steers fed medium-quality grass hay

Objectives of this research were to evaluate effects of increasing level of barley supplementation on forage intake, digestibility, and ruminal fermentation in beef steers fed medium-quality forage. Four crossbred ruminally cannulated steers (average initial BW = 200 +/- 10 kg) were used in a 4 x 4 Latin square design. Chopped (5 cm) grass hay (10% CP) was offered ad libitum with one of four supplements. Supplements included 0, 0.8, 1.6, or 2.4 kg of barley (DM basis) and were fed in two equal portions at 0700 and 1600. Supplements were fed at levels to provide for equal intake of supplemental protein with the addition of soybean meal. Forage intake (kg and g/kg BW) decreased linearly (P < 0.01), and total intake increased linearly (P < 0.03) with increasing level of barley supplementation. Digestible OM intake (g/kg BW) increased linearly (P < 0.01) with increasing level of barley supplementation; however, the majority of this response was observed with 0.8 kg of barley supplementation. Treatments had only minor effects on ruminal pH, with decreases occurring at 15 h after feeding in steers receiving 2.4 kg of barley supplementation. Total-tract digestibility of DM, OM, NDF, and CP were increased (P < 0.04) with barley supplementation; however, ADF digestibility was decreased by 1.6 and 2.4 kg of barley supplementation compared with controls. Ruminal ammonia concentrations decreased linearly (P < 0.01) at 1 through 15 h after feeding. Total ruminal VFA concentrations were not altered by dietary treatments. Ruminal proportions of acetate and butyrate decreased (P < 0.10) in response to supplementation. Rate, lag, and extent (72 h) of in situ forage degradability were unaffected by treatment. Generally, these data are interpreted to indicate that increasing levels of barley supplementation decrease forage intake, increase DM, OM, and NDF digestibility, and indicate alteration of the ruminal environment and fermentation patterns.     

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.