Ruminal Liquid Dilution Rate Research Articles

Daily and alternate day supplementation of urea or soybean meal to ruminants consuming low-quality cool-season forage: II. Effects on ruminal fermentation

Five ruminally cannulated steers (initial BW=464±26kg) consuming low-quality forage (5% CP; 78% NDF; DM basis) were used in an incomplete 5×4 Latin square with four 18-d periods to determine the influence of supplemental N source and supplementation frequency (SF) on ruminal fermentation dynamics. Treatments, arranged as a 2×2 factorial with a negative control, consisted of urea or soybean meal (SBM) supplements offered daily (D) or alternate days (2D) plus an unsupplemented treatment (CON). Urea supplements were provided to meet 100% of the degradable intake protein requirement while SBM supplements were provided on an isonitrogenous basis. All supplemented treatments received an equal quantity of supplemental N over a 2-d period. Ruminal indigestible acid detergent fiber (IADF) passage rate was increased with supplementation (P≤0.03) on the days when D and 2D supplements were provided, as well as when only D supplements were provided. In contrast, ruminal liquid fill and dilution rate were not affected by supplementation, N source, or SF on the days when D and 2D supplements were provided (P≥0.24). However, when only D supplements were offered, ruminal liquid dilution rate was greater (P=0.03) for SBM supplemented steers compared with cohorts receiving supplemental urea, whereas ruminal liquid fill was greater (P=0.03) for steers fed urea supplements. Nitrogen supplementation increased (P<0.01) ruminal NH3–N by 122% and 70%, compared with the CON, on the days when both D and 2D supplements were provided and when only D supplements were provided, respectively. We noted a N source×SF interaction for ruminal NH3–N on the days when D and 2D supplements were provided (P=0.02), as well as when only D supplements were provided (P<0.01). On the days when D and 2D supplements were provided, urea increased NH3–N by 61% (2.93 vs. 4.73mM for D and 2D, respectively), whereas the increase in NH3–N with SBM was only 15% (2.23 vs. 2.58mM for D and 2D, respectively). However, when only D supplements were provided, NH3–N was almost 36% less for the 2D compared with the D urea treatment (2.76 vs. 1.81mM, respectively), whereas an 11% increase was noted for SBM 2D compared with SBM D (1.99 vs. 1.79mM, respectively). Total concentration of VFA was increased on the days when both D and 2D supplements were provided (P=0.03), but not influenced by treatments on the days when only D supplements were provided (P≥0.50). In summary, providing a urea-based supplement, as infrequently as every-other-day, was an effective alternative to a SBM-based supplement in maintaining acceptable ruminal fermentation of steers consuming low-quality, cool-season forage.

Response of Lactating Dairy Cows to Diets Containing Wet Corn Gluten Feed or a Raw Soybean Hull-Corn Steep Liquor Pellet

We evaluated effects of wet corn gluten feed (WCGF) and a novel product (SHSL) containing raw soybean hulls and corn steep liquor on performance and digestion in lactating dairy cows. In Experiment 1, 46 multiparous Holstein cows were assigned to control (C), WCGF (20% of diet DM), or SHSL (20% of diet DM). Diets were fed as a total mixed ration beginning after calving. The C diet contained (dry matter [DM] basis) 30% alfalfa hay, 15% corn silage, 32% corn, 9.3% whole cottonseed, 4.4% solvent soybean meal (SBM), and 3.3% expeller SBM. The WCGF replaced 10% alfalfa hay, 5% corn silage, and 5% corn grain, while expeller SBM replaced solvent SBM to maintain diet rumen undegradable protein. The SHSL replaced 10% alfalfa hay, 5% corn silage, 3% solvent SBM, and 2% corn. Dietary crude protein averaged 18.4%. Milk, energy-corrected milk (ECM), DM intake (DMI), and ECM/DMI were similar among diets during the first 13wk of lactation. During wk 14 through 30 postpartum, WCGF and SHSL improved milk, ECM, milk component yield, and ECM/DMI. In Experiment 2, 6 cows were used to evaluate digestibility and rumen traits. Dry matter intake and total tract digestibilities of DM, fiber, and crude protein were not different among diets. Diets did not affect ruminal liquid dilution rate, pH, or concentrations of total volatile fatty acids or ammonia, but acetate:propionate was higher for C (3.38) than for WCGF (2.79) or SHSL (2.89). The WCGF and SHSL products can serve as alternative feedstuffs in diets fed to lactating dairy cattle.

Effects of Tallow in Diets Based on Corn Silage or Alfalfa Silage on Digestion and Nutrient Use by Lactating Dairy Cows

Six multiparous Holstein cows (average 31 days in milk; 36.3 kg/d of milk) fitted with ruminal cannulas were used in a 6×6 Latin square with 21-d periods to investigate the effects of diets that varied in forage source and amount of supplemental tallow. Isonitrogenous diets in a 2×3 factorial arrangement were based on either high corn silage (40:10 corn silage to alfalfa silage, % of dry matter) or high alfalfa silage (10:40 corn silage to alfalfa silage, % of dry matter) and contained 0, 2, or 4% tallow. Intakes of dry matter and total fatty acids were lower when cows were fed the high corn silage diet. Tallow supplementation linearly decreased dry matter intake. Milk yield was unaffected by diet; yields of milk fat and 3.5% fat-corrected milk were higher for the high alfalfa silage diet but were unaffected by tallow. Milk fat percentage was higher for the high alfalfa silage and tended to decrease when tallow was added to the high corn silage diet. Contents of trans-C18:1 isomers in milk fat were increased by high corn silage and tallow, and tended to be increased more when tallow was fed in the high corn silage diet. Ruminal pH and acetate:propionate were lower when high corn silage was fed. Ruminal acetate:propionate decreased linearly as tallow increased; the molar proportion of acetate was decreased more when tallow was added to the high corn silage diet. Ruminal liquid dilution rates were higher for the alfalfa silage diet; ruminal volume and solid passage rates were similar among diets. Total tract apparent digestibilities of dry matter, organic matter, crude protein, starch, energy, and total fatty acids were unaffected by diet. Digestibilities of neutral detergent fiber, acid detergent fiber, hemicellulose, and cellulose were lower when high corn silage was fed. The high alfalfa silage diet increased intakes of metabolizable energy and N, and increased milk energy and productive N. Tallow decreased the amount of N absorbed but had few other effects on utilization of energy or N. Tallow linearly increased concentrations of nonesterified fatty acids and cholesterol in plasma; cholesterol was increased by high alfalfa silage. Overall, forage source had more pronounced effects on production and metabolism than did tallow supplementation. Few interactions between forage source and tallow supplementation were detected except that ruminal fermentation and milk fat content were affected more negatively when tallow was fed in the high corn silage diet.

Influence of rumen protein degradability and supplementation frequency on steers consuming low-quality forage: II. Ruminal fermentation characteristics.

Seven ruminally and duodenally cannulated steers (264 +/- 8 kg BW) consuming low-quality forage (5% CP; 61% NDF; 31% ADF) were used to determine the influence of CP degradability and supplementation frequency (SF) on ruminal fermentation characteristics. Treatments included an unsupplemented control and degradable intake protein (DIP) or undegradable intake protein (UIP) provided daily, every 3 d, or every 6 d. The DIP treatments (18% UIP) were calculated to provide 100% of the DIP requirement, while the UIP treatments (60% UIP) were provided on an isonitrogenous basis compared with DIP. Ruminal NH3-N was increased on the day all supplements were provided with supplemental CP (P = 0.04) and for DIP compared with UIP (P < 0.01). Also, because ruminal NH3-N increased at a greater rate with DIP compared with UIP as SF decreased, a linear effect of SF x CP degradability interaction (P = 0.02) was observed. In addition, NH3-N was greater on the day only daily supplements were provided for supplemented treatments (P = 0.04), and decreased linearly (P < 0.01) as SF decreased. Concentration of total VFA increased linearly (P = 0.02) as SF decreased on the day all supplements were provided, whereas on the day only daily supplements were provided, total VFA were greater for UIP compared with DIP (P = 0.01), and decreased linearly (P < 0.01) as SF decreased. An interaction concerning the linear effect of SF and CP degradability (P = 0.02) was observed for ruminal liquid volume on the day all supplements were provided. This was the result of an increase in liquid volume with DIP as SF decreased compared with a minimal effect with UIP. In contrast, there was no influence of supplementation on liquid volume the day only daily supplements were provided. Ruminal liquid dilution rate was greater (P = 0.02) with CP supplementation on the day all supplements were provided. We did observe a quadratic effect of SF x CP degradability interaction (P = 0.01) for dilution rate because of a quadratic response with DIP (greatest value with the every-third-day treatment) compared with a decrease as SF decreased for UIP. On the day only daily supplements were provided, ruminal liquid dilution rate decreased linearly (P = 0.02) as SF decreased. These results suggest that DIP and UIP elicit different effects on ruminal fermentation when supplemented infrequently to ruminants consuming low-quality forage while not adversely affecting nutrient intake and digestibility.

Low- and high-quality forage utilization by heifers and mature beef cows.

Eight cows (7 to 9 yr old, 522 kg) and six heifers (10 mo old, 169 kg) were fed either alfalfa hay (18.7% CP) or mature brome hay (5.1% CP) to determine the effect of cattle age on apparent forage utilization. Cattle were fitted with ruminal and duodenal cannulas and were individually fed once daily (ad libitum intake, 1000). The split-plot design consisted of age (whole-plot) and two sampling periods feeding alfalfa or brome hay (subplot). Each period consisted of 28 d: d 1 to 13 for adaptation, d 13 to 20 for feed intake determination, and d 20 to 28 for sampling. Nylon bags containing NDF substrate from alfalfa or brome hay were incubated ruminally for 0, 3, 6, 12, 24, 48, 96, and 192 h to determine the rate and extent of fiber degradation. Ruminal liquid dilution rate and fermentation characteristics were conducted on d 27. Ruminal fill was determined by total evacuation at 0800 on d 28. Cows consumed more feed (BW.75; P<.01) and had greater ruminal OM fill (P = .04) but had similar fluid fill (P = .88) compared with heifers. Ruminal liquid dilution rate was greater in cows than in heifers (P<.01). The rate of in situ NDF degradation was 3 and .5% per hour greater in cows than in heifers when alfalfa and brome hay were fed, respectively (age x hay, P<.01). Ruminal NDF digestibility as a percentage of intake was greater in cows than in heifers (P<.01). Numbers of ruminal cellulolytic bacteria were not affected by treatment (P>.21). These data indicate that mature cows have a smaller ruminal fluid fill that turns over more rapidly, and this may be responsible for a faster rate of ruminal fiber degradation in cows than in young heifers.

The influence of restricted feeding on site and extent of digestion and flow of nitrogenous compounds to the duodenum in steers.

The effects of restricted feeding on site and extent of digestion, flow of N-containing compounds to the duodenum, and ruminal metabolism were determined. In Trial 1, corn silage-based diets were fed at one of three intakes to three ruminally and duodenally fistulated steers (420 +/- 4.4 kg BW) in a repeated 3 x 3 Latin square experiment. Feeding levels were 100% of ad libitum intake, 90% of ad libitum intake, and 80% of ad libitum intake. Site of digestion was not affected by restricted feeding; however, extent of DM, NDF, and apparent N digestion were increased (P < .03) 2.8, 4.1, and 6.2 percentage units for each 1-kg restriction in DM intake. Restricted feeding increased (P < .06) ruminal pH and ammonia concentrations, decreased (P < .05) ruminal liquid dilution rate, and had no major effects on bacterial concentrations. In Trial 2, all-concentrate diets based on whole shelled corn were fed at 100, 90, or 80% of ad libitum intake to six ruminally and duodenally fistulated steers (440 +/- 4.1 kg BW) in a replicated 3 x 3 Latin square experiment. Restricted feeding increased (P < .06) apparent ruminal DM digestion; however, true ruminal OM digestibility was not affected. Extent of apparent N digestion increased 3.0 percentage units for each 1-kg restriction in DMI. Ruminal pH was not affected by restricted feeding; however, ruminal ammonia concentrations increased (P < .06) and ruminal liquid dilution rate decreased (P < .04) with restricted feeding. In both Trials, total N flow to the duodenum was approximately 100% of N intake for the 80% of ad libitum intake. Flow of N exceeded N intake in a linear (P < .01) manner as DMI increased. Decreases in duodenal N flow when intake was restricted resulted from decreases (P < .01) in bacterial N flowing to the duodenum, and also in decreases (P < .01) in non-ammonia, non-bacterial N flow when whole shelled corn-based diets were fed. We concluded that restrictions in digestible energy intake are less than the DM restriction when corn silage-based diets are fed but are equal to the DM restriction when whole shelled corn-based diets are fed. Also, restricted feeding strategies reduce the flow of N to the duodenum from both bacterial and feed origins.

Effect of water-filled bags in the rumen of wethers on ruminal digesta kinetics and total tract nutrient digestibility

Four ruminal cannulated wethers (65 +/- 2.4 kg) were used in a Latin square design experiment to determine the effects of water-filled bags on ruminal liquid and particulate dilution rates. Treatments consisted of ratios of water volume (liters) in bags to pretrial ruminal volume (liters) and were A) 0, B) .22, C) .44, and D) .66. Diet DM, consisting of 75% concentrate and 25% chopped alfalfa hay, was offered once daily at 2.3% of each wether's pretrial live weight. The largest water-filled bag decreased ruminal liquid volume by 68%, increased ruminal liquid dilution rate by 64%, and increased ruminal pool size of non-water soluble concentrate (NWSC) by 137% compared with the control. Ruminal dilution rate of ytterbium-marked NWSC decreased by 37% compared with the control. Ruminal fluid concentrations of NH3 N, pH, and molar ratios of acetate, propionate, butyrate, and isovalerate and plasma urea nitrogen varied over time postfeeding depending on water-filled bag size. Total tract apparent digestibility of DM, OM, ADF, starch, and energy were decreased (P less than .05) with increasing water-filled bag size in the rumen. In this study, water-filled bags acted to increase ruminal liquid dilution rate and decrease ruminal liquid volume and total tract nutrient digestibility but to retard passage of NWSC and hay fiber.

Effects of protein supplementation and parasympathetic stimulation with slaframine on utilization of low quality roughage fed to goats and sheep

Eighteen Angora goats (average BW 14 kg) and 18 Barbados Blackbelly X Dorset sheep (average BW 24 kg), all wethers, were fed chopped coastal bermudagrass hay (84% neutral detergent fiber (NDF), 6% crude protein (CP)) ad libitum and offered only alfalfa hay or cottonseed meal as protein supplement during an 84-day feeding trial. From day 28, animals received daily injections of physiological saline with or without the parasympathomimetric slaframine (SF) at 30 μg kg −1 BW. Digestibility and digesta kinetics measurements were made during a 7-day fecal collection period. Goats had lower ( P< 0.05) intakes of DM, NDF and CP than sheep. There were no differences in digestibility of DM, NDF or CO between species. Protein supplementation increased digestibility of DM ( P< 0.05), NDF ( P< 0.10), and CP ( P< 0.01) without affecting intake. No differences were due to type of supplement in intake and digestibility. SF depressed ( P< 0.05) intake of DM, NDF and CP and tended ( P<0.10) to lower DM and CP digestibility. Protein supplementation increased ( P<0.05) and SF decreased ( P< 0.01) weight gain. Animals receiving protein supplement lost less body weight (BW) after SF treatment than those receiving no supplement. Goats and sheep apparently utilized low quality roughages differently but responded similarly to protein supplementation. SF was not effective in altering ruminal liquid dilution rate or enhancing nutrient digestibility in goats and sheep fed high fiber diets.

Influence of Addition of Yeast Culture Supplement to Diets of Lactating Cows on Ruminal Fermentation and Microbial Populations

Six ruminally fistulated Holstein cows were utilized in a randomized block design to examine effects of yeast culture supplement on ruminal metabolism and apparent digestibility. Cows were fed a diet of 40% corn silage and 60% concentrate (DM basis). Treatments were control (supplement without yeast cells) and yeast culture supplement. Treatment periods were 6 wk. Ruminal pH, ammonia, molar proportions of acetate and isovalerate, and acetate:propionate ratio were lower and molar proportions of propionate and valerate higher in cows receiving yeast. The concentration of anaerobic bacteria tended to be higher and cellulolytic bacteria concentrations were greater in cows fed yeast than in cows receiving control diet. Supplemental yeast did not affect molar proportions of isobutyrate or butyrate, total VFA, or viable yeast concentrations in ruminal fluid. Ruminal liquid dilution rate and total tract apparent digestibilities were not different between treatments. Rate of disappearance of cellulose in vitro was lower in cows receiving yeast. Less variation in ammonia concentrations and mircobial numbers suggest that ruminal fermentation was more stable in cows receiving yeast culture supplement.

Effects of ammoniation of tall fescue on phenolic composition, feed intake, site and extent of nutrient digestion and ruminal dilution rates of steers.

Tall fescue hay (H) supplemented with corn and urea (HU) or corn gluten meal (HCGM) and ammoniated tall fescue hay supplemented with corn (AH) or corn gluten meal (AHCGM) were fed to steers in two 4 X 4 Latin-square trials. Diets were fed to four Angus-Hereford steers (550 kg) at equal intakes in trial 1 and to four Hereford steers (350 kg) at ad libitum intakes in trial 2. Ammoniation reduced cell wall concentrations of p-coumaric acid and ferulic acid by 48 and 67%, respectively. Concentrations of other phenolics were also reduced. Apparent total tract digestibilities of vanillin, p-coumaric acid and ferulic acid were lower (P less than .05, .001 and .01, respectively) when nontreated hay was fed in trial 1, but were not different between hay types in trial 2. In trial 1, greater negative intestinal digestibilities of p-coumaric acid (P less than .001) and vanillin (P less than .05) occurred for steers fed HU and HCGM vs AH and AHCGM diets. Digestibilities of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were greater (P less than .001) for steers fed ammoniated hay diets in both trials and greater (P less than .05) for HCGM vs HU in trial 1. More than 96% of the NDF and ADF digested by steers in trial 1 was digested in the stomach. Intakes of digestible NDF and ADF, but not indigestible NDF or ADF, were higher (P less than .001) for steers fed AH and AHCGM in trial 2. In situ dry matter disappearance rate of ammoniated hay was greater (P less than .05) than that of nontreated hay, but rate of cotton thread disappearance from bags suspended in the rumen of steers fed the various diets was similar among treatments. In both trials, feeding ammoniated hay resulted in higher (P less than .05) ruminal concentrations of acetate and higher (P less than 0.05) acetate:propionate ratios. Ruminal liquid dilution rates were lower (P less than .05) for steers fed AH and AHCGM in trial 1, but were not different in trial 2. Ruminal dry matter concentration and solids dilution rate were not affected by diet in either trial. The results are interpreted to indicate that increased intake of ammoniated hay is a result of increased rate and extent of fiber digestion.

Effect of Feeding Frequency on Diurnal Dry Matter and Water Consumption, Liquid Dilution Rate, and Milk Yield in First Lactation

Four ruminally cannulated cows in first lactation (50 days postpartum) were assigned randomly to a 4×4 Latin square with the following feeding frequencies of the same total mixed ration: one, two, four, and eight times a day. Dry matter intake, water consumption, and ruminal pH were recorded hourly during 4-d collection (10-d adaptation between periods, Experiment 1). In Experiment 2, 30 animals were blocked by milk production on wk 4 postpartum and assigned to feeding one or four times a day through wk 19 postpartum. Individual feed consumption and milk production were recorded daily.Hourly consumption patterns of dry matter and water were variable over 24h; once daily feeding tended to be more variable than other frequencies. Cows fed four times a day had higher ruminal liquid dilution rates than those fed eight times; feeding once and twice a day was not different from either. In Experiment 2, frequency of feeding total mixed ration had no significant influence on dry matter intake or milk yield; however, cows fed four times a day exhibited a consistent weekly tendency to be lower in dry matter intake and higher in milk yield than those fed once daily. Efficiency of fat-corrected milk production was slightly higher for cows fed four times than for those fed once daily.

Effect of Sodium Bicarbonate Addition to Alfalfa Hay-Based Diets on Digestibility of Dietary Fractions and Rumen Characteristics

Three trials were to evaluate effects of sodium bicarbonate in alfalfa hay-based diets. In Experiment 1, four Jersey cows were fed diets of 40:60 chopped alfalfa hay:grain with either 0, .25, .5, and .75% sodium bicarbonate in a 4×4 Latin square digestion trial. Dry matter and fiber digestion were unaffected. Volatile fatty acids of ruminal fluid and milk fatty acids were not different. In Experiment 2, two rumen fistulated cattle were fed diets of Experiment 1 for changes of ruminal fluid characteristics at −1, 2, 4, and 8h postfeeding. Volatile fatty acids of ruminal fluid and hydrogen ion concentration were not different across time with sodium bicarbonate. In Experiment 3, four Holstein cows with rumen cannulae were fed diets of 30:70 chopped alfalfa hay:grain with 0, .4, .8, and 1.2% sodium bicarbonate in a 4×4 Latin square. Dry matter and fiber digestion were unaffected. Ruminal fluid samples were collected at −1, 3, 6, and 9h postfeeding. Volatile fatty acids were different only at 6h with 0 and 1.2% sodium bicarbonate diets displaying lower concentrations. Rate of increase of hydrogen ion concentration was greater for diets containing 0 and .4% compared with .8 and 1.2% sodium bicarbonate between −1 and 6h. Milk fatty acid composition, ruminal liquid dilution rate, and dry matter disappearance from nylon bags suspended in the rumen were not affected by sodium bicarbonate.

Corn Particle Size and Site and Extent of Digestion by Steers

The site and extent of starch digestion by steers as influenced by corn particle size was studied in a 4 × 4 Latin square design. Steers (272 kg) fitted with permanent rumen cannulae were fed approximately 3.5 kg dry matter in eight portions daily (3-hr intervals). Site of digestion was estimated by withdrawing rumen samples and assuming such samples would be equivalent to abomasal samples if a constant flow of digesta was maintained by frequent feeding. Ruminal digestion of dry matter (DMD), organic matter (OMD) and starch was estimated by the ratio of permanganate lignin in feed to lignin in rumen digesta. Corn was fed whole or following grinding through 3.18, 4.76 or 7.94mm screens and comprised 72% of the diets. Geometric mean diameters (micrometers) of the four grains were as follows: whole (5978 $#x03BC;m), 3.18mm (509 μm), 4.76mm (588 μm) and 7.94mm (832 μm). In view of high and variable lignin digestibilities, ruminal digestibility estimates indicate trends rather than absolute values. Ruminal DMD was lower (P<.05) for whole corn (44.9%) than for that ground through 3.18mm (62.3%), 4.76mm (63.6%) and 7.94mm (60.8%) screens. This permitted intestinal DMD to be greater (P<.05) for whole corn and suggests increased quantitative importance of intestinal digestion for whole corn. Whole corn also had a lower (P<.05) ruminal starch digestibility (70.8%) than ground corn treatments (avg 91.7%). Moreover, total tract starch digestion was lower for whole 88.2%) than for 3.18mm (94.5%), 4.76mm (93.7%) and 7.94mm (93.5%) treatments. Intestinal starch digestion was generally low, particularly on ground corn treatments. Alteration of the whole kernel beyond mastication appears necessary to maximize total starch digestion. Rumen pH and liquid outflow rate were not greatly influenced by corn particle size, but tended to increase with particle size. Fecal pH was not related to starch content of feces and ruminal liquid dilution rate was not related to molar percentage acetate, propionate or butyrate.