Effects of supplemental urea sources and feeding frequency on ruminal fermentation, fiber digestion, and nitrogen balance in beef steers

Abstract A metabolism study was conducted using 8 ruminal cannulated beef heifers to investigate the effects of a recombinant fibrolytic enzyme (RFE; xylanase XYL10C) selected specifically for forage-fed ruminants on ruminal pH, fermentation, nitrogen balance, and total tract digestibility of heifers. The experiment was a cross-over design with 2 treatments and 2 periods. The 2 treatments were a basal diet containing 60% barley silage, 30% barley straw, and 10% supplement (DM basis) without (control) or with RFE. The enzyme was sprayed onto the barley straw at a rate of 6.6 × 104 IU·kg−1 DM 24 h before feeding. Each period comprised 2 wk of diet adaptation and 1 wk of sampling and data collection. Feed intake and total tract digestibility of DM, OM, NDF, and ADF were unaffected by RFE. Ruminal pH including mean, minimum, maximum, and duration pH <5.8, did not differ between treatments. Total VFA concentration, molar proportion of individual VFA, and acetate-to-propionate ratio were also not affected by RFE. However, ruminal NH3-N concentration (P < 0.06) and endoglucanase activity (P < 0.08) in ruminal fluid tended to be higher with RFE. Nitrogen utilization and microbial protein synthesis were not affected by treatment. These results indicate that XYL10C did not improve fiber digestion in heifers fed a high forage diet, despite the fact that it was specifically selected for this trait in laboratory assays. However, the increased ruminal NH3-N concentration suggests it potentially increased ruminal proteolytic activity.

Download Full-text

PSXII-23 Effects of a recombinant fibrolytic enzyme on fiber digestion, ruminal fermentation, nitrogen balance and total tract digestibility of heifers fed a high forage diet

Journal of Animal Science ◽

10.1093/jas/skz258.832 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 419-420

Author(s):

Tao Ran ◽

Atef Saleem ◽

YiZhao Shen ◽

Gabriel Ribeiro ◽

Adrian Tsang ◽

...

Keyword(s):

Nitrogen Balance ◽

Fixed Effects ◽

Barley Straw ◽

Ruminal Fermentation ◽

Sample Collection ◽

Beef Heifers ◽

Endoglucanase Activity ◽

Fiber Digestion ◽

Ruminal Ph ◽

High Forage

Abstract The objective of this study was to investigate the effects of a recombinant fibrolytic enzyme (RFE; xylanase XYL10C) on ruminal pH and fermentation characteristics, total tract digestibility and nitrogen balance in beef heifers. The experiment was a cross-over design with two treatments and two periods, using eight ruminal cannulated beef heifers. The treatments were a basal diet containing 60% barley silage, 30% barley straw and 10% supplement (DM basis) without (control) or with RFE. The RFE XYL10C was selected specifically for ruminants using a high throughput in vitro micro assay and was sprayed onto the barley straw at a rate of 6.6 × 104 IU/kg DM 24 h before feeding. The diet was prepared daily using a data ranger. Each period was 21 d, with a 14-d adaptation and 7-d sample collection period. The digestibility and nitrogen balance were measured by total fecal and urine collection. Data were analyzed using the PROC MIXED procedure of SAS with fixed effects of treatment, and random effects of period and heifer. Feed intake (8.9 kg/d) and total tract digestibility of DM (65.5%), NDF (57.2%) and ADF (51.2%) were not affected by RFE. Ruminal pH including mean (6.52), minimum (5.79), maximum (7.05), and duration of pH < 5.8 (0.64, h/d) did not differ between treatments. No treatment effects were observed for total VFA concentration (106 mM), molar proportion of acetate (68.2%) and propionate (17.5%) and acetate to propionate ratio (3.94). However, adding RFE vs. control tended (P < 0.08) to increase ruminal NH3-N concentration (5.75 vs. 5.23 mM) and endoglucanase activity (44.3 vs. 40.7 µmol glucose/min/mL wet rumen contents). There were no differences in nitrogen utilization and rumen microbial protein synthesis (90.7 g/d) between treatments. The results indicate that RFE XYL10C did not improve fiber digestion in heifers fed a high forage diet.

Download Full-text

Feeding strategies for improving productivity of growing steers fed grass silage

Canadian Journal of Animal Science ◽

10.4141/cjas08008 ◽

2008 ◽

Vol 88 (4) ◽

pp. 685-692

Author(s):

D. R. Ouellet ◽

L. Faucitano ◽

D. Pellerin ◽

M. D’Amours ◽

R. Berthiaume

Keyword(s):

Particle Size ◽

Soybean Meal ◽

Nitrogen Balance ◽

Average Daily Gain ◽

Latin Square ◽

Feeding Strategies ◽

Beef Steers ◽

Plasma Urea ◽

Grass Silage ◽

Ground Corn

Two experiments were conducted to determine the relationship between corn particle size and soybean meal treatment on growth, diet digestibility, and nitrogen balance of growing steers. In the first experiment, 40 medium-frame beef steers (250 ± 11 kg) were fed individually for 140 d a diet based on grass silage offered for ad libitum consumption and supplemented with either 3.5 kg of DM d-1 of cracked corn (CC) or ground corn (GC) and with 450 g of DM d-1 of solvent extracted (SS) or lignosulfonate-treated soybean meal (Soypass™ SP). Dry matter intake was not affected by treatments and averaged 8.6 ± 0.3 kg d-1 (P > 0.10). Average daily gain was higher for animals receiving the ground corn than those fed cracked corn. Feed to gain ratio was not affected by treatments. There was an interaction between treatments for plasma urea-N concentration, with source of soybean meal having no effect with CC. When compared with SS, SP supplement reduced plasma urea-N when fed with GC. No effect of soybean meal and its interaction with corn processing was observed on growth performance. In the second experiment four additional steers were used in a 4 × 4 Latin square design to evaluate diet digestibility and nitrogen balance. There was an interaction between treatments for starch apparent digestibility and N retained, the values being respectively, 90, 86, 93, and 92% (SEM = 1.2; P < 0.01) and 36, 42, 44 and 41 g d-1 (SEM = 2.8; P < 0.03) for CCSS, CCSP, GCSS and GCSP, respectively. Altogether, the results indicate a slight advantage to reduce particle size of corn in growing steers fed grass silage. However, soybean meal treatment resulted in limited effects on growth and digestion. Key words: Rumen carbohydrate, undegradable protein, performance, steers

Download Full-text

Effects of roughage type on particle separation, rumination, fiber mat characteristics, in situ degradation, and ruminal fermentation parameters in beef steers

Journal of Animal Science ◽

10.1093/jas/skab214 ◽

2021 ◽

Author(s):

Catherine L Lockard ◽

Caleb G Lockard ◽

Wyatt N Smith ◽

Kendall J Karr ◽

Ben P Holland ◽

...

Keyword(s):

Dry Matter ◽

Rumen Fluid ◽

Fluid Collection ◽

Latin Square ◽

Experimental Unit ◽

Beef Steers ◽

Ruminal Fermentation ◽

In Situ Degradation ◽

Fermentation Parameters

Abstract Six ruminally cannulated steers (average BW = 791 + 71 kg) were used in a replicated 3 × 3 Latin square experiment to determine the effects of roughage type on rumination, fiber mat characteristics, and rumen fermentation variables. Three roughages were included at 7% (DM basis) in a steam flaked corn-based diet; cotton burrs (CB), wheat silage (WS), or corn stalks (CS). Steers were fitted with a sensory collar to record rumination behaviors in 2-h intervals at the beginning of the experiment. Each 30-d period consisted of a 7-d of recovery, 14-d of diet adaptation, 7-d of rumination data collection (daily and bi-hourly average rumination), 1-d of rumen fluid collection, and 1-d of rumen evacuations. In situ degradation of individual roughages was determined for 4-d after period 3 evacuations. During rumen evacuations, ruminal contents were removed; the rumen fiber mat (RF) was separated from the liquid portion with a 2 mm sieve, weighed, and a subsample was dried. Data were analyzed using the MIXED procedure of SAS with steer as the experimental unit and roughage (CB, WS, and CS) as the main effect. Dry matter intake (DMI) was not different for CB and WS (P = 0.25) and greatest for steers consuming CS diet (P < 0.01). Roughage type did not influence the weight of the RF dry matter (%; DM; P = 0.92), RF weight (P = 0.69), or RF:DMI ratio (P = 0.29). Daily rumination (min/d) did not differ among roughages (P = 0.40), but min of rumination/kg of DMI was greatest for CS (18.0 min), min/kg of NDF was greatest for WS (89.8 min; P = 0.02), and min/kg of peNDF was greatest for CS (132.4 min; P < 0.01). Wheat silage had the greatest percentage of soluble DM and CB-R and CS-R (P < 0.01) had the greatest ruminal degraded DM fraction. Rumen fiber mat did not differ for roughages, although rumination min/kg of DMI and peNDF was greatest for steers consuming CS and WS. In situ degradation determined that CB-R and CS-R had the greatest percentage of ruminal degraded DM. Based on the objective of the experiment, roughage type did not influence daily rumination or fiber mat characteristics.

Download Full-text