Digestion In Steers Research Articles

Effects of calcium propionate on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in steers

SUMMARYThe objective of the current study was to evaluate the effects of calcium propionate supplementation on rumen fermentation, urinary excretion of purine derivatives (PD) and feed digestibility in the total gastrointestinal tract of steers. Eight ruminally cannulated Simmental steers (462±14 kg) were used in a replicated 4×4 Latin square arrangement of treatments with experimental periods of 21 days. The treatments were: control (without calcium propionate), LCaP (calcium propionate – low), MCaP (calcium propionate – medium) and HCaP (calcium propionate – high) with 100, 200 and 300 g calcium propionate per steer per day. Diet consisted of 0·60 maize stover and 0·40 concentrate (dry matter (DM) basis). DM intake (average 9 kg/day) was restricted to a maximum of 0·90 ofad libitumintake. Ruminal pH (range of 6·7–6·5) linearly (P<0·003) and quadratically (P<0·005) decreased, and total volatile fatty acid (VFA) concentration (range of 64·4–67·1 mm) tended (P<0·087) to increase linearly with rising calcium propionate supplementation. Ratio of acetate to propionate fell linearly (P<0·006) and quadratically (P<0·008) from 3·5 to 2·6 as calcium propionate supplementation increased due to the additional propionate supplementation.In situruminal neutral detergent fibre (NDF) degradation of maize stover and crude protein (CP) degradability of concentrate mix were improved with increasing concentration of calcium propionate. Urinary excretion of PD was linearly (P<0·032) and quadratically (P<0·048) increased with greater calcium propionate supplementation (72, 74, 77 and 76 mmol/day for control, LCaP, MCaP and HCaP, respectively). Similarly, digestibilities of organic matter (OM), NDF and CP in the total tract were also linearly and quadratically improved with increasing calcium propionate. The results indicate that the calcium propionate supplementation potentially improves rumen fermentation and feed digestion in beef cattle. It is speculated that calcium propionate stimulates the digestive microorganisms or enzymes in a dose-dependent manner. In the experimental conditions of the current trial, the optimum calcium propionate dose was about 200 g calcium propionate per steer per day.

Effects of malic acid on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in steers

The objective of this study was to evaluate the effects of malic acid (MA) supplementation on rumen fermentation, urinary excretion of purine derivatives (PDs) and whole gastro-intestinal tract feed digestibility in steers. Eight ruminally cannulated Simmental steers (465 ± 13 kg) were used in a replicated 4 × 4 Latin square design. The treatments were: control (without MA), LMA (MA-low), MMA (MA-medium) and HMA (MA-high) with 0.0, 7.8, 15.6 and 23.4 g MA per kg dry matter (DM), respectively. Diets consisted of corn stover and concentrate (60/40, DM basis). DM intake was approximately 9 kg per day, which was 90% of ad libitum intake including 5.4 kg corn stover and 3.6 kg concentrate. Ruminal pH (range of 6.91 to 6.56), ratio of acetate to propionate (range of 3.88 to 3.25), ammonia N (range of 9.03 to 6.42 mg/100 ml) and lactate (range of 91.25 to 76.31 mg/100 ml) decreased linearly as MA supplementation increased, whereas total volatile fatty acid (VFA) concentration (range of 55.68 to 61.49 mM) linearly (P < 0.05) increased with increase in MA supplementation. In situ ruminal neutral detergent fiber (aNDF) degradation of corn stover was improved but the crude protein (CP) degradability of concentrate mix was decreased with increasing the dose of MA. Urinary excretion of PDs was quadratically (P < 0.01) changed with altering MA supplementation (67.88, 72.74, 75.81 and 73.78 mmol/day for control, LMA, MMA and HMA, respectively). Similarly, digestibilities of DM, organic matter (OM), NDF and acid detergent fiber (ADF) in the total tract were also quadratically increased with increasing MA, and no differences in terms of CP and ether extract digestibility were observed. The results indicate that MA supplementation has the potential to improve rumen fermentation and feed digestion in beef cattle. The MA stimulates the digestive microorganisms or enzymes in a quadratic response. In the experimental conditions of this trial, the optimum MA dose was 15.6 g MA per kg DM.

Effects of isobutyrate on rumen fermentation, urinary excretion of purine derivatives and digestibility in steers

The objective of this study was to evaluate the effects of isobutyrate supplementations on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in steers. Eight ruminally cannulated Simmental steers were used in a replicated 4 × 4 Latin square experiment. On DM basis, diet consisted of 60% corn stover and 40% concentrate. Dry matter intake (averaged 9 kg/d) was restricted to 90% of ad libitum intake. The four treatment groups received a daily dose of 0 (control), 8.4, 16.8 or 25.2 g isobutyrate per steer. With increasing isobutyrate supplementation total VFA concentration (range 64.2–74.0 mM) was significantly enhanced. The ratio of acetate to propionate (range 2.72–4.25) was also significantly increased due to the increase in actate production and decrease in propionate production. With increasing isobutyrate supplementation the ruminal degradation of NDF from corn stover was improved but the CP degradability of soybean meal was decreased. Furthermore, the isobutyrate supplementation caused a significantly increased urinary excretion of purine derivatives. Similarly, digestibilities of OM, NDF and CP in the total tract were significantly increased. The present results indicate that dietary supplementation with isobutyrate improved rumen fermentation and feed digestion in beef cattle in a dose-dependent manner. According to the conditions of this experiment, the optimum daily dose of isobutyrate was about 16.8 g/animal.

Effects of exogenous fibrolytic enzymes on ruminal digestibility in steers fed high fiber rations

The effects of two exogenous fibrolytic enzyme products on ruminal disappearance and fermentation of oat straw-wheat middlings based diets were evaluated. Six steers (322 ± 34.4 kg body weight) fitted with ruminal cannulas were used in a 3 × 3 Latin square replicated. The treatments consisted of: 1) control, 2) Fibrozyme (2 g/kg dry matter), and 3) Promote (3 ml/kg dry matter). Both, Fibrozyme (Alltech Inc.) and Promote NET (Cargill Corp.) were sprayed as liquid onto diets and feeds 24 h before feeding. Samples of diets were ruminally incubated from 0 to 72 h. Enzymes did not change dry matter intake, average daily gain and feed conversion. Fibrozyme increased crude protein (CP) disappearance rate of diet, while Promote increased CP total disappearance. In diets, enzymes did not affect ruminal neutral detergent fiber (NDF) and acid detergent fiber (ADF) fractions. Fibrozyme and Promote did increase CP total disappearance, ADF potential disappearance and ADF disappearance rate of wheat middlings, as well as dry matter (DM) and CP total disappearance, NDF disappearance rate, ADF potential disappearance and ADF disappearance rate of oat straw. Ruminal pH values were higher with enzymes, as compared to control. Total volatile fatty acids concentration and molar proportion of acetate and butyrate were not affected by both enzymes, but molar proportion of propionate was lower and acetate:propionate ratio higher with Promote than control. Fibrozyme and Promote did increase DM and CP soluble fractions of diets, as well as, ADF potential disappearance of wheat middling and oat straw.

Effects of glycerol on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in steers

The objective of this study was to evaluate the effects of glycerol supplementation on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in the total tract of steers. Eight ruminally cannulated Simmental steers (450 ± 12 kg) were used in a replicated 4 × 4 Latin Square arrangement of treatments with experimental period of 21 days long. The treatments were: control (without glycerol), LG, MG and HG with 100, 200 and 300 g glycerol per head per day, respectively. Diet consisted of 60% corn stover and 40% concentrate (dry matter [DM] basis). Dry matter intake (averaged 9 kg/day) was restricted to a maximum of 90% of ad libitum intake. Ruminal pH (range of 6.58 to 6.23) was linearly ( P < 0.05) decreased, whereas total VFA concentration (range of 93.40 to 99.61 mM) was linearly ( P < 0.03) increased with increasing glycerol supplementation. Ratio of acetate to propionate decreased linearly ( P < 0.02) from 4.56 to 3.64 as glycerol supplementation increased due to the increased in propionate production. In situ ruminal NDF degradation of corn stover was improved but the CP degradability of concentrate mix was decreased with increasing doses of glycerol. Urinary excretion of purine derivatives was quadratically ( P < 0.02) changed with altering glycerol supplementation (65.0, 65.7, 71.1 and 67.2 mmol/d for control, LG, MG and HG, respectively). Similarly, digestibilities of OM, NDF and CP in the total tract were also linearly increased with increasing glycerol. The results indicate that glycerol supplementation potentially improves rumen fermentation with increased propionate production and feed digestibility in the total digestive tract of beef cattle. It suggests that feeding glycerol stimulates the ruminal microorganisms or digestive enzymes in a dose-dependent manner. Under the current experimental conditions, the optimum glycerol dose was about 200 g glycerol per head per day.

Effects of calcium magnesium carbonate and roughage level on feedlot performance, ruminal metabolism, and site and extent of digestion in steers fed high-grain diets1,2

A feedlot growth performance experiment and 2 metabolism experiments were conducted to evaluate dietary roughage concentration and calcium magnesium carbonate in steers fed a high-grain diet. In Exp. 1, one hundred ninety-two crossbred yearling steers (320 +/- 10 kg of initial BW) were fed diets based on steam-flaked corn with 0, 0.75, or 1.5% CaMg(CO(3))(2). There were no effects (P > or = 0.13) on ADG, DMI, G:F, or total water intake due to CaMg(CO(3))(2). In Exp. 2, five ruminally and duodenally fistulated steers (263 +/- 9 kg of initial BW) were used in a 5 x 5 Latin square design, with 5 dietary treatments arranged in a 2 x 2 + 1 factorial: 1) 3.8% dietary roughage and no CaMg(CO(3))(2); 2) 7.6% dietary roughage and no CaMg(CO(3))(2); 3) 11.4% dietary roughage and no CaMg(CO(3))(2); 4) 3.8% dietary roughage and 1.5% CaMg(CO(3))(2); and 5) 7.6% dietary roughage and 1.5% CaMg(CO(3))(2). Water consumption was less (quadratic, P = 0.003) when 7.6% dietary roughage was fed compared with 3.8 or 11.4% dietary roughage. Intake of DM was not affected (P > or = 0.16) by dietary roughage or by CaMg(CO(3))(2). Poststomach and total tract starch digestion decreased (linear, P < 0.01) as dietary roughage increased. Ruminal pH tended (P = 0.08) to increase as dietary roughage increased but was not affected (P = 0.60) by CaMg(CO(3))(2). In Exp. 3, DMI and ruminal pH were continuously monitored in a 6 x 6 Latin square design using 6 ruminally and duodenally fistulated Holstein steers (229 +/- 10 kg of initial BW). A 3 x 2 factorial treatment structure was utilized, with factors consisting of dietary roughage concentration (4.5, 9.0, or 13.5%) and CaMg(CO(3))(2) inclusion (0 or 1.0%) to replace MgO and partially replace lime-stone. A dietary roughage x CaMg(CO(3))(2) interaction (P = 0.01) occurred as steers consuming 13.5% roughage, 1.0% CaMg(CO(3))(2) had greater DMI per meal than those consuming 4.5% dietary roughage, no CaMg(CO(3))(2) and 9.0% dietary roughage, 1.0% CaMg(CO(3))(2). Steers consuming 13.5% dietary roughage, 1.0% CaMg(CO(3))(2) and 9.0% dietary roughage, no CaMg(CO(3))(2) had greater meal length (min/meal; P = 0.01) than steers consuming 4.5% dietary roughage, no CaMg(CO(3))(2). Total tract OM digestibility decreased linearly (P = 0.01), and ruminal pH increased linearly (P = 0.01) with increasing dietary roughage concentration. Inclusion of CaMg(CO(3))(2) can replace limestone and MgO but did not produce ruminal pH responses similar to those observed by increasing dietary roughage in high-concentrate diets.

Effects of supplemental fat source on nutrient digestion and ruminal fermentation in steers1

Five Holstein steers (235 kg of BW) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 5 Latin square design experiment to determine the effects of supplemental fat source on site and extent of nutrient digestion and ruminal fermentation. Treatments were diets based on steam-flaked corn containing no supplemental fat (control) or 4% (DM basis) supplemental fat as tallow, dried full-fat corn germ (corn germ), corn oil, or flax oil. Fat supplementation decreased (P < 0.08) ruminal starch digestion but increased (P < 0.03) small intestinal starch digestion as a percentage of intake. Feeding corn germ decreased (P < 0.09) ruminal starch digestion and increased (P < 0.03) large intestinal starch digestion compared with steers fed corn oil. Large intestinal starch digestion was less (P < 0.04), and ruminal NDF digestion was greater (P < 0.09) for steers fed tallow compared with steers fed other fat sources. Small intestinal (P < 0.08) and total tract NDF digestibilities were greater (P < 0.02) for steers fed corn germ than for those fed corn oil. Feeding tallow increased total ruminal VFA (P < 0.03) and NH(3) (P < 0.07) concentrations compared with steers fed the other fat sources. Feeding corn germ led to a greater (P < 0.02) rate of ruminal liquid outflow compared with corn oil. A diet x hour interaction (P < 0.04) occurred for ruminal pH, with steers fed corn oil having the greatest ruminal pH 18 h after feeding, without differences at other time points. Fat supplementation increased (P < 0.09) ruminal concentrations of Fusobacterium necrophorum. Duodenal flow of C18:3n-3 was greater (P < 0.01) for steers fed flax oil compared with those fed corn oil. Feeding corn germ led to less (P < 0.01) ruminal biohydrogenation of fatty acids compared with corn oil. Steers fed tallow had greater small intestinal digestibility of C14:0 (P < 0.02) and C16:1 (P < 0.04) than steers fed the other fat sources. Fat supplementation decreased (P < 0.06) small intestinal digestibility of C18:0. Feeding corn germ decreased (P < 0.10) small intestinal digestibility of C18:1 compared with corn oil. It appears that source of supplemental fat can affect the site and extent of fatty acid and nutrient digestion in steers fed diets based on steam-flaked corn.

Effects of lanthanum on rumen fermentation, urinary excretion of purine derivatives and digestibility in steers

The objective of this study was to evaluate the effects of LaCl 3 supplementation on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in the total tract of steers. Eight ruminally cannulated Simmental steers (420 ± 20 kg) were used in a replicated 4 × 4 Latin square experiment. The treatments were control (without LaCl 3); La-low; La-medium and La-high with 450, 900 and 1800 mg LaCl 3 per steer per day, respectively. Diet consisted of 600 g/kg corn stover and 400 g/kg concentrate (dry matter [DM] basis). Dry matter intake (averaged 9 kg/day) was restricted to a maximum of 90% of ad libitum intake. Ruminal pH (range of 6.59–6.42) was quadratically (P<0.04) changed, whereas total volatile fatty acids (VFA) concentration (range of 74.16–88.61 mM) was linearly (P<0.01) and quadratically (P<0.01) increased with increasing La supplementation. Ratio of acetate to propionate decreased linearly (P<0.01) from 3.28 to 1.79 as La supplementation increased due to the increased in propionate production. In situ ruminal neutral detergent fibre (aNDF) degradation of corn stover was improved but the crude protein (CP) degradability of soybean meal was decreased with increasing La supplementation. Urinary excretion of purine derivatives was quadratically (P<0.01) changed with altering La supplementation (75.5, 81.0, 82.4 and 70.6 mmol/day for control, low-, medium- and high-LaCl 3 supplementation, respectively). Similarly, digestibilities of organic matter, aNDF and CP in the total tract were also linearly and quadratically increased with increasing La supplementation. The present results indicate that supplementation of diet with LaCl 3 improved rumen fermentation and feed digestion in beef cattle. It was suggested that the La stimulated the digestive microorganisms or enzymes in a dose-dependent manner. In the experimental conditions of this trial, the optimum La dose was about 900 mg LaCl 3 per steer per day.

Influence of soybean hull supplementation on rumen fermentation and digestibility in steers consuming freshly clipped, endophyte-infected tall fescue1

Six steers (288.6 +/- 2.1 kg of BW) fitted with rumen and duodenal cannulas were used in a crossover design to evaluate intake, rumen fermentation, and site of nutrient digestion of freshly clipped, endophyte-infected (E+) Kentucky 31 tall fescue with or without soybean hull (SH) supplementation at 0.60% of BW (OM basis). Steers were placed in metabolism units within an environmentally controlled room and provided with free-choice access to fresh forage, water, and a vitamin/mineral supplement. The spring growth of E+ tall fescue was harvested daily during the experiment. Supplement was fed at 0700 with approximately 65% of the estimated daily forage. To maintain a fresh forage supply, additional forage was stored in a cooler and fed at 1900. Periods were 21 d with 14 d of adaptation and 7 d of digesta sample collection. Chromic oxide was used as a marker of duodenal digesta flow. Duodenal samples were taken 4 times daily with times shifting by 1 h each day to represent all 24 h of a day. Treatments were considered significant at P < 0.05. Supplementation of SH decreased forage OM intake from 1.64 to 1.41% of BW but increased total OM intake from 1.64 to 2.01% of BW. Apparent percentages (53.1%) and quantities (2,786 g/d) of rumen OM disappearance were not affected by supplementation. Percentages of total tract OM disappearance were not different (70.8%). Percentages of apparent rumen NDF disappearance also were not different (65.6%). Percentages of N disappearance were not different. Supplementation of SH resulted in increased total N (34.1 g/d) and microbial N (17.1 g/d) flowing to the duodenum. Rumen pH (6.5) was not affected, and rumen ammonia concentrations exhibited a time x treatment interaction in which SH decreased ammonia for 12 h after supplementation. Total VFA concentrations (103.9 mM) were unaffected. Liquid dilution rate (12.7%/h) and rumen OM fill (4.3 kg) were not different between treatments. Supplementation of SH at a rate of 0.60% of BW (OM basis) to calves consuming fresh E+ tall fescue decreased forage consumption but resulted in greater total intake, greater flow of N to the duodenum, and increased total tract OM disappearance.

Effect of energy source and ruminally degradable protein addition on performance of lactating beef cows and digestion characteristics of steers.

Two trials were conducted to determine the effect of energy source (ENG) and ruminally degradable protein (RDP) on lactating cow performance and intake and digestion in beef steers. In Trial 1, 78 cow-calf pairs were used in a 2 x 2 factorial design to determine the effect of ENG (corn or soyhulls; SH) and RDP (with our without sunflower meal) to a forage diet for lactating beef cows. The basal diet consisted of 75% grass hay (11.5% CP) and 25% wheat straw (7.4% CP). Supplement treatments and predicted RDP balances were corn (-415 g of RDP/d); SH (-260 g of RDP/d); corn plus RDP (0 g of RDP/d); or SH plus RDP (0 g of RDP/d). Data were analyzed as a split-plot in time, with pen as the experimental unit (two pens per treatment). No interaction between ENG and RDP was present (P > 0.08) for any response variable. No differences (P > 0.39) due to ENG or RDP were noted for BW, BCS, or milk yield; however, final calf weight tended to increase with ENG (P = 0.06). In Trial 2, a 5 x 5 Latin square was used to determine effects of ENG and RDP on intake and digestion in steers (686 +/- 51 kg BW). Treatments were arranged as a 2 x 2 plus one factorial and comprised a control (CON; grass hay, 7% CP), grass hay plus 0.4% BW SH, grass hay plus 0.4% BW SH and 0.15% BW sunflower meal, grass hay plus 0.4% BW corn, and grass hay plus 0.4% BW corn and 0.2% BW sunflower meal. Preplanned contrasts included main effects of ENG and RDP, ENG x RDP interaction, and CON vs. supplemented (SUP) treatments. Supplementation increased total DMI compared with CON (P = 0.001), but forage DMI was greater (P = 0.001) for CON than for SUP. An ENG x RDP interaction occurred for forage DMI (P = 0.02); addition of RDP to corn decreased forage intake, whereas addition of RDP to SH had no effect. There was an ENG x RDP interaction (P = 0.001) for ruminal pH; pH tended to increase with RDP addition to SH (P = 0.07), but decreased with RDP addition to corn (P = 0.001). Supplementation increased ruminal ammonia compared with CON (P = 0.001). Likewise, RDP increased ruminal ammonia (P = 0.001). An interaction occurred for OM disappearance (OMD; P = 0.01). The RDP addition to SH numerically decreased OMD (P = 0.23), whereas RDP addition to corn numerically increased OMD (P = 0.14). Intake and digestion seem to respond differently to RDP addition depending on supplemental energy source. Both corn or SH seem to be suitable supplements for the quality of forage used in this trial. Addition of supplemental protein did not improve cow or calf performance.

Daily and alternate-day supplementation of urea or biuret to ruminants consuming low-quality forage: II. Effects on site of digestion and microbial efficiency in steers.

Five steers (491 +/- 21 kg BW) were used in an incomplete 5 x 4 Latin square with four 24-d periods to determine the influence of supplemental non-protein N (NPN) source and supplementation frequency (SF) on nutrient intake and site of digestion in steers consuming low-quality grass straw (4% CP). Treatments (TRT) included an unsupplemented control and a urea- or biuret-containing supplement placed directly into the rumen daily (D) or every other day (2D) at 0700. The NPN treatments were formulated to provide 90% of the estimated degradable intake protein requirement. Daily TRT were supplemented CP at 0.04% of BW/d, whereas the 2D TRT were supplemented at 0.08% of BW every other day. Therefore, all supplemented TRT received the same quantity of supplemental CP over a 2-d period. Forage OM intake was not affected (P > 0.05) by NPN supplementation, NPN source, or SF; however, total OM and N intake were increased (P < 0.01) with CP supplementation. Duodenal flow of N was greater (P = 0.04) with CP supplementation compared with the control. In addition, duodenal bacterial N flow was increased with CP supplementation (P = 0.04) and for biuret compared with urea (P < 0.01). Bacterial efficiency (g bacterial N/kg OM truly digested in the rumen) was greater (P = 0.05) for biuret than for urea. Apparent total-tract N digestibility was increased with NPN supplementation (P < 0.01) but not affected by NPN source or SF. These results suggest that urea or biuret can be used effectively as a supplemental N source by steers consuming low-quality forage.

Evaluation of n-alkanes as markers for estimation of dry matter intake and digestibility in steers consuming all-forage or forage-concentrate diets

The study examined the reliability of the alkane-based and chromium (Cr)/in-vitro-based procedures relative to the total fecal collection (TC) technique for estimation of dry matter (DM) intake an d DM digestibility of forage or forage-concentrate diets fed to steers. Eight Holstein steers (208 ± 19.2 kg) were assigned to four dietary treatments in a three-period balanced incomplete block design. The four dietary treatments were: (1) 100% meadow brome grass hay (B); (2) 50% B + 50% alfalfa hay (BA); (3) 50% B + 50% barley grain (BB); and (4) 25% B + 25% alfalfa hay + 50% barley grain (BAB). Two types of hay were chosen to achieve a wide range of alkane intake. Appropriate portions of forages and grain were mixed as a total mixed ration and fed in two equal portions twice daily at 2.5% of body weight, DM basis. Two controlled-release capsules, one containing n-alkanes (C32 and C36) and the other chromic oxide, were placed into the steer's reticulo-rumen by oral administration on day 1 of each 30-d period. Total fecal output was collected twice daily from day 8 to 14 of each period to establish the fecal recovery of Cr and the alkanes, and to determine apparent DM digestibility. A rectal fecal grab sample was also taken every 4 h from day 15 to 16. Fecal recovery of the natural alkanes, C31 and C33, was low, ranging from 59.5 to 77.3%, whereas the range in fecal recovery of the dosed alkanes, C32 and C36, was 83.3 to 95.5%, and of Cr was 82.7 to 95.8% across the diets. The estimated DM intake was similar across all diets using the C31/C32 and C33/C32 alkane ratios; however, estimated DM intakes using the alkane method were significantly (P &lt; 0.05) lower compared to TC and Cr/in vitro methods for the BB diet. Addition of barley to the forage diets resulted in a higher DM digestibility for BB and BAB diets by all methods. The estimated DM digestibility using the C31/C32 ratio was lower compared to the TC method for diet B, BA and BB, whereas the estimated DM digestibility using C33/C32 was lower only for the BB diet. Sampling every 4 h resulted in a significantly higher ratio of C 31 to C32 in feces compared to samples collected by the TC method. Rectal grab sampling did not change (P &gt; 0.05) the estimated DM intake using either combination of alkane ratio. Key words: Alkanes, chromium oxide, dry matter intake, dry matter digestibility, steer

Effect of the substitution of urea for soybean meal on digestion in steers

Four growing Holstein steers (305 ± 33 kg body weight) with ruminal and duodenal cannulae were used in a 4 × 4 Latin square experiment to assess the effect of level of dietary urea (0, 7.3, 14.7 and 22.0 g kg−1 of dry matter) on the site and extent of digestion of some feed components. The diets were isonitrogenous and consisted of 60% ryegrass hay and 40% concentrate and were offered to the animals three times daily in amounts limited to 24 g of dry matter kg−1 liveweight in order to avoid feed refusals. The addition of urea caused a linear increase in ruminal pH and in ruminal ammonia concentration during the first hours after feed ingestion (P &lt; 0.01), and linearly increased ruminal digestibility of cellulose (P &lt; 0.01) and apparent nitrogen (P &lt; 0.05). However, it had no significant effect on apparent total digestibility of feed components, nor did it affect ruminal digestibility of dry matter, organic matter or starch. Flow of microbial nitrogen to the small intestine decreased linearly (P &lt; 0.05), but the efficiency of microbial protein synthesis or the proportion of undegraded feed nitrogen in the rumen that flowed to the small intestine was not significantly affected (P &gt; 0.05). The increase in ruminal ammonia concentration above that necessary for optimal microbial growth increased ruminal nitrogen losses into the blood. However, excess ruminal ammonia concentration also increased ruminal fibre digestion. Key words: Non-protein nitrogen, microbial protein synthesis, ruminants, digestion

Effect of Tween 80 and salinomycin on ruminal fermentation and nutrient digestion in steers fed a diet containing 70% barley

Ten Jersey steers (484 ± 55 kg) were fed a basal diet of 70% rolled barley grain and 30% alfalfa silage [dry matter (DM) basis] with or without additives, in a replicated 5 × 5 Latin square experiment. Treatments (additives per kilogram dietary DM) were: C, no additives (control); T, Tween 80 (2 g kg−1); SH, salinomycin (13 mg kg−1); TSM, Tween 80 (2 g kg−1) plus salinomycin (6.5 mg kg−1); and TSL, Tween 80 (2 g kg−1) plus salinomycin (3.25 mg kg−1). Ruminal pH, concentrations of ammonia, total free amino acids, reducing sugars and total volatile fatty acids (VFA), and fluid phase viscosity were unaffected (P &gt; 0.05) by treatment. Ruminal carboxymethylcellulase, xylanase and amylase activities, numbers of protozoa, and outflow rates of the liquid and solid phases of ruminal contents did not differ (P &gt; 0.05) among treatments. Ruminal lactic acid bacteria populations tended (P &lt; 0.1) to be smaller with SH compared with C, but counts were unaffected (P &gt; 0.05) by T, TSL and TSM. Partitioning of ruminal digesta and microbial protein flow were similar (P &gt; 0.05) among treatments. Compared with C, the ruminal rate of degradation (in situ) of alfalfa DM tended to be higher (P &lt; 0.10) with SH, and the rate of barley grain DM degradation was higher (P &lt; 0.05) with T. Intake and apparent digestibilities of DM, neutral detergent fibre (NDF), acid detergent fibre (ADF) and crude protein were unaffected (P &gt; 0.05) by treatment, as were blood glucose and urea levels. Tween 80 and salinomycin did not affect ruminal fermentation or nutrient digestibility in steers fed a barley grain/alfalfa silage diet. Key words: Tween 80, salinomycin, ruminal fermentation, digestibility, steer

Ruminal Forage Dry Matter, Crude Protein and Fiber Digestion in Steers Fed Alfalfa Hay and Supplemented with Fresh Onion Bulbs or Cracked Corn

Pasinato, A., Sevilla, G. and García, J. 1999. Ruminal forage dry matter, crude protein and fiber digestion in steers fed alfalfa hay and supplemented with fresh onion bulbs or cracked corn. J. Appl. Anim. Res., 16: 169–175. Feeding fresh culled onion to the ruminant livestock is a common practice in Argentine. For studying the in situ ruminal digestion of dry matter, crude protein and fiber of alfalfa hay in steers fed alfalfa hay and supplemented with onion bulbs or com grain, four cannulated steers were allotted to two treatments, alfalfa hay and 0.5% body weight dry matter basis of fresh onions (To) or cracked corn (Tc), arranged in a cross-over design. Forage soluble dry matter fraction was lower (P<0.05) but the rate of digestion was higher (P<0.05) in animals supplemented with onion bulbs. There were no differences (P>0.05) in the kinetics of crude protein and, fiber degradation between the two treatments.

Supplemental cracked corn for steers fed fresh alfalfa: I. Effects on digestion of organic matter, fiber, and starch.

The effect of supplementation with different levels of cracked corn on the sites of OM, total dietary fiber (TDF), ADF, and starch digestion in steers fed fresh alfalfa indoors was determined. Six Angus steers (338 +/- 19 kg) fitted with cannulas in the rumen, duodenum, and ileum consumed 1) alfalfa (20.4% CP, 41.6% NDF) ad libitum (AALF); 2), 3), and 4) AALF supplemented (S) with .4, .8, or 1.2%, respectively, of BW of corn; or 5) alfalfa restricted at the average level of forage intake of S steers (RALF), in a 5 x 5 Latin square design. Total OM intake was lower (P < .01) in steers fed RALF than in those fed AALF but level of forage intake did not affect sites of OM, TDF, or starch digestion (P > .05). Forage OM intake decreased (P < .01) linearly (8,496 to 5,840 g/d) but total OM intake increased (P = .03) linearly (8,496 to 9,344 g/d) as corn increased from .4 to 1.2% BW. Ruminal apparent and true OM disappearance was not affected, but OM disappearing in the small intestine increased (P < .01) linearly with increasing levels of corn. Total tract OM digestibility (71.2 to 76.2%) and the proportion of OM intake that was digested in the small intestine (15.4 to 24.5%) increased (P < .01) linearly as corn increased. The TDF and ADF intakes decreased (P < .01) linearly as level of corn increased. Total tract TDF and ADF digestibilities were not different among treatments (average 62.9 and 57.8%, respectively). Starch intake and starch digested in the rumen and small and large intestine increased (P < .01) linearly with increasing corn level. Ruminal pH and VFA concentrations decreased and increased (P < .01), respectively, with increasing corn. Supplementation with corn increased OM intake, decreased forage OM intake, and increased the proportion of OM that was digested in the small intestine, but fiber digestion was not affected.

Effects of saturation and esterification of fat sources on site and extent of digestion in steers: digestion of fatty acids, triglycerides, and energy.

Five steers (mean BW 526 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 6 Youden square design with 14-d periods. Diets contained chopped alfalfa hay, corn silage, and concentrate (25:35:40, DM basis). Treatments were 1) control (no added fat); 2) tallow (T), iodine value (IV) = 51.5; 3) partially hydrogenated tallow (PHT), IV = 30.7; 4) hydrogenated tallow (HT), IV = 6.9; 5) blend (1: 1) of HT and hydrogenated free fatty acids (HTHFA), IV = 9.0; and 6) hydrogenated free fatty acids (HFA), IV = 11.2. Fats replaced cornstarch in the control diet to supply 5% added fatty acids. Intake was restricted to 90% of ad libitum; DMI was similar among diets (mean 9 kg/d). Total fatty acid intake averaged 170, 500, 506, 525, 489, and 491 g/d for treatments 1 to 6, respectively. Flows of total C16, total C18, and total fatty acids to the duodenum were increased by supplemental fat; flows of total C18 and total fatty acids were greater than their intake for all treatments. Flow of total fatty acids associated with ruminal bacteria accounted for 50 and 17% of the total duodenal fatty acid flow for the control and fat-supplemented diets, respectively. Digestibility of total fatty acids entering the small intestine (74, 71, 62, 39, 53, and 63% for treatments 1 to 6, respectively) was greater for the control diet than for fat-supplemented diets and decreased as either saturation (T < PHT < HT) or esterification (HFA < HTHFA < HT) increased. Digestibilities of fatty acids in the total tract followed similar patterns. Ruminal lipolysis of dietary triglycerides decreased linearly as the degree of saturation of fat sources increased. Small intestinal disappearance of triglycerides (89, 75, 51, 44, 64, and 73% of duodenal flow for treatments 1 to 6, respectively) decreased linearly as either saturation or esterification increased. Flows and digestion of gross energy followed patterns similar to those for fatty acids and triglycerides. Resistance to ruminal and small intestinal lipolysis is a major factor contributing to the poor digestibility of highly saturated triglycerides.

Influence of the nature of cereal on site and extent of starch digestion in steers

Influence of the nature of cereal on site and extent of starch digestion in steers

Performance and digestion by steers grazing tall fescue and supplemented with energy and protein.

We studied the effects of different levels of protein and energy supplementation on BW gains and sites of nutrient digestion in steers grazing the primary growth of endophyte-infected tall fescue (Festuca arundinacea Schreb cv. Kentucky 31). Angus steers (n = 168; mean BW = 246.8 +/- 15.0 kg) grazed tall fescue without supplementation (C) or were supplemented with 1.4 kg/d of cracked corn (CC1), 1.4 kg/d of corn gluten feed (CGF1), 2.8 kg/d of CC (CC2), 2.8 kg/d of CGF (CGF2), or .7 kg/d of cornstarch and .7 kg/d of corn gluten meal (CS-CGM) during an 85-d period in a randomized complete block design. Supplemented steers (S) had a higher (P = .03) ADG than the control steers (.64 vs .74 kg/d). There was an interaction (P = .02) between supplement type and level. Supplementation during the grazing period had no effect on subsequent feedlot ADG (average 1.3 kg/d). In a digestion study, Angus x Simmental steers (n = 4; 412 +/- 20.4 kg) fitted with cannulas in the esophagus, rumen, and duodenum grazed tall fescue (C), C + 3.1 kg/d CGF, C + 3.1 kg/d of cracked corn (CC), or C + 1.4 kg/d CS-CGM over four experimental periods in a Latin square design. The ruminal ammonia nitrogen concentration tended to be higher (P < .09) in C than in CGF and in CC (21.9 vs 19.2 mg/dL), but ruminal pH and total VFA concentration did not differ among treatments. Forage OM intakes were lower (P < .05) in steers supplemented with CC or CGF (an average of 7,570 g/d) than in C (9,658 g/d). Total OM intakes and digestibilities did not differ (P > .10) among treatments. Duodenal N flows and efficiencies of net ruminal microbial protein synthesis were not different (P > .10) among treatments. Supplementation of steers grazing primary growth of tall fescue improved animal gain but did not have a great effect on ruminal fermentation, OM digestion, or net ruminal microbial protein synthesis.

The effect of diet and frequency of watering on rumen degradability and outflow rate of low-quality veld hay and dry-matter apparent digestibility in steers given food at maintenance

AbstractThe effect of water restriction on rumen degradability and outflow rate of low quality veld hay and dry-matter apparent digestibility was investigated in four rumen cannulated Tuli × Friesian steers (mean weight 329 (s.d. 36·6) kg) given food at maintenance (metabolizable energy allowance (maintenance) (MJ) = 8·3 + 0·091 M). Two diets with 20: 80 (low, L) and 80:20 (high, H) roughage to concentrate ratios were used in combination with free access to water for 2·5 h once daily or once every 3rd day. A 4 × 4 Latin-square design with a 2 (diets) × 2 (watering frequencies) factorial arrangement of treatments was used.The degradation pattern of veld hay was not affected by the type of diet and the watering frequency. Although the effective degradabilities of hay in steers given the two diets were low (177 and 258 g/kg for L and H, respectively), they were significantly different (P &lt; 0·05) from each other. However, watering frequency did not affect the effective degradability of hay (218 and 217 g/kg). While the low roughage diet had a higher rumen outflow rate for Crmordanted hay than the high roughage diet (0·047 per h and 0·031 per h), this was not statistically significant. The same outflow rate was obtained for the two watering frequencies (0·039 per h).