Rumen Dry Matter Research Articles

The effect of Lactobacillus buchneri on the fermentation, aerobic stability and ruminal degradability of maize silage

To evaluate the effect of Lactobacillus buchneri, heterofermentative lactic acid bacteria (LAB), on the fermentation, aerobic stability and ruminal degradability of whole-crop maize silages under laboratory conditions. Two homofermentative LAB were tested for the purpose of comparison. Maize was harvested at early dent [290 g kg(-1) dry matter (DM)] and one-half milk line (355 g kg(-1) DM) stages. Both homofermentative LAB were applied at 1 x 10(5) CFU g(-1) of fresh forage. Lactobacillus buchneri was applied at 1 x 10(5), 5 x 10(5) and 1 x 10(6) CFU g(-1) of fresh forage. Silages with no additives served as control. After treatment, the chopped forages were ensiled in 1.5-l anaerobic jars. Three jars per treatment were sampled on day 60. After 60 days of storage, silages were subjected to an aerobic stability test lasting for 5 days, in which CO(2) production, as well as chemical and microbiological parameters, was measured to determine the extent of aerobic deterioration. Both homofermentative LAB increased the concentration of lactic acid and the numbers of yeasts, and decreased the concentration of acetic acid and impaired the aerobic stability of silages. In contrast, applying L. buchneri decreased the concentration of lactic acid and increased the concentration of acetic acid of the silages. Under aerobic conditions, silages treated with 5 x 10(5) and 1 x 10(6) CFU g(-1) of L. buchneri, had lower pH, CO(2) production and the numbers of yeasts than the silages treated with 1 x 10(5) CFU g(-1) of L. buchneri (P < 0.05). However, all doses of L. buchneri and both homofermentative LAB did not affect in situ rumen DM, organic matter and neutral detergent fibre degradability of the silages. Lactobacillus buchneri was very effective in protecting maize silages exposed to air under laboratory conditions. All doses of L. buchneri, especially 5 x 10(5) CFU g(-1) or more, markedly decreased the numbers of yeasts and improved the aerobic stability of silages. The use of L. buchneri, as a silage inoculant, can improve the aerobic stability of maize silages by inhibition of yeast activity.

Comparison between in vitro gas production and in situ degradation for evaluating rumen dry matter degradation of maize grain and tropical grasses

SummaryThe in situ technique (NB) was compared to the in vitro gas production technique (Gas) in terms of ability to estimate the dry matter degradation (DMD) using high soluble substrates (maize grains) and low soluble substrates (four tropical forages). The experiments (in situ and in vitro) were carried out at the same time using the same cow for both techniques and DMD was estimated at 6, 12, 24, 48 &amp; 96 h. The results showed that DMD from Gas were lower than NB DMD and the correlation for the maize group were lower than those of the grass group which indicated that Gas technique, closed system, has potential to analyse highly soluble substrates, probably, overcoming the particle losses effect demonstrated by the in situ technique.

The digestibility and degradability of mixtures of Napier grass and Sesbania leaves

Increasing proportions of Sesbania leaves mixed with Napier grass improved in sacco rumen dry matter degradability, organic matter degradability and nitrogen degradability, as well as the in vitro dry matter digestibility. Copyright © 2006 John Wiley & Sons, Ltd

Nutritive Value of Fresh Swine Excreta for Growing Pelibuey Sheep

GCantón, J.J., Belmar-Casso, R. and Sandoval-Castro, C.A. 2005. Nutritive value of fresh swine excreta for growing pelibuey sheep. J. Appl. Anim. Res., 27: 89–94. To study the utilization of fresh swine excreta (FSE) in growing Pelibuey sheep two experiments were carried out. In the first experiment, twelve male sheep (20±1.7 kg) were allocated in a randomized block design to four diets containing 0 (D0), 200 (D20), 400 (D40) and 600 (D60) g FSE/kg dry matter (DM). Water and DM intake as well as the digestibility of DM, organic matter (OMD), crude fibre and gross energy (GE) were higher (P<0.05) for the DO diet, although OMD was similar (P>0.05) for DO and D60 diets. N balance was similar (P>0.05) for DO, D20 and D60 diets. In the second experiment, rumen fermentation pattern and 48h in situ rumen DM degradation of Cynodon nlemfluensis were studied in four Pelibuey sheep fed similar diets as in experiment 1 in a 4 × 4 Latin square design. Plasma urea and NH3 were higher (P<0.05) in DO diet, although NH 3 was not different from D60 diet (P>0.05). Total VFA and its molar proportion were similar for all diets. Rumen pH was lower (P<0.05) for the D60 diet. No effect was found on DM degradation, rumen outflow and rumen turnover rates. It was concluded that FSE is a valuable source of nitrogen for sheep and it can be fed up to levels of 600 g/kg DM.

Increasing the intake of highly digestible Persian clover herbage reduces rumen fluid pH and the rate of degradation of neutral detergent fibre in grazing dairy cows

An experiment was conducted to investigate the hypothesis that increasing the intake of Persian clover (Trifolium resupinatum L.) would decrease rumen fluid pH and the rate of loss of neutral detergent fibre from nylon bags. It was further hypothesised that the reduction in the rate of disappearance of neutral detergent fibre with increased intake would be less in highly digestible clover than in highly digestible ryegrass or pasture hay. Sixteen rumen fistulated cows, in late lactation, were used in a completely randomised, split-plot design for 33 days. There were 4 pasture allowance treatments (9, 16, 32 and 53 kg dry matter (DM)/cow.day of Persian clover) with 4 cows per treatment. Cows grazed in individual plots, pasture intakes were measured, and rumen fluid and in sacco measurements were undertaken. Pasture DM intake increased asymptotically as pasture allowance increased from 9 to 53 kg DM. Cows grazing at the 9 kg pasture allowance spent less time grazing than cows at higher allowances (294 v. 368, 421 and 414 min, P&lt;0.05). Cows grazing at the 2 lower allowances spent less time grazing at night than cows at the 2 higher allowances. There was no effect (P&gt;0.05) of pasture allowance on time spent ruminating, which averaged 236 min. Estimated rates of intake increased (P&lt;0.05) with pasture allowance. Average daily rumen fluid pH decreased linearly (P&lt;0.05) with pasture intake, with the averages for the pasture allowance treatments being 6.03, 5.95, 5.83 and 5.79 as pasture allowance increased. The patterns of rumen fluid pH over 24 h indicated that it was only late in the night that treatment differences were detected, with the lower pasture allowance treatments recording higher rumen fluid pH values than the higher pasture allowance treatments. There was no effect of pasture allowance on average daily rumen fluid ammonia-N concentrations (25 mg/100 mL). Total volatile fatty acids concentrations averaged 139, 152, 163 and 168 mmol/L as pasture allowance increased from 9 to 53 kg DM/cow.day. The proportion of acetate in total volatile fatty acids generally declined (71.4, 70.4, 67.4 and 69.2%; s.e.d. = 1.14) and the proportion of propionate generally increased (15.2, 15.5, 17.6 and 17.0%; s.e.d. = 0.77) as pasture allowance increased from 9 to 53 kg DM/cow, respectively. Rate of neutral detergent fibre loss from nylon bags was highest in clover, and lowest in hay, and was higher in cows grazing at 9 and 16 kg allowances compared with cows at 32 and 53 kg (P&lt;0.05). There was a linear relationship (P&lt;0.05) between rate of neutral detergent fibre loss and rumen fluid pH for clover and ryegrass, but not hay (P&gt;0.05). There were no differences (P&gt;0.05) in total rumen contents (75.6 kg; s.e.d. = 6.95), or DM (7.3 kg; s.e.d. = 0.73) and neutral detergent fibre (2.7 kg; s.e.d. = 0.32) pools, of cows grazing at different allowances. Offering cows increasing allowances of Persian clover pasture reduced rumen digesta retention times, as rumen pool sizes did not change. Average daily pH fell with increasing allowance due to differences in daily intake and pH patterns, and increasing pasture allowance decreased the rate of disappearance of neutral detergent fibre. It is suggested that increased outflow rates, driven by differences in daily pH patterns and changes in substrate composition, were responsible for the decline in disappearance of neutral detergent fibre from nylon bags, but the effects of the factors cannot be separated.

Chemical composition, in vitro dry matter digestibility and ruminal degradation of Napier grass ( Pennisetum purpureum (L.) Schumach.) mixed with different levels of Sesbania sesban (L.) Merr.

An experiment to assess the effect of different levels of Sesbania leaves on chemical composition, in vitro dry matter (DM) digestibility (IVDMD), in sacco rumen DM degradability (DMD), organic matter degradability (OMD) and crude protein (CP) degradability (CPD) of Napier grass– Sesbania mixtures was conducted. There were four Napier– Sesbania mixtures (100, 150, 200 and 250 g/kg of Sesbania on a DM basis) and Napier grass only (control) in a randomised complete block design. As the proportion of Sesbania increased in the mixture, there was an increase in CP, Ca and metabolizable energy, and a reduction in P, neutral detergent fibre (NDF), acid detergent fibre (ADF), cellulose and hemicellulose contents. The DMD, OMD, CPD and IVDMD increased as the proportion of Sesbania leaves increased. Results indicate that different levels of Sesbania forages have desirable characteristics as a potential feed supplement to improve the utilization of Napier grass to ruminant animals under tropical condition. Moreover, it could be concluded that nutrient content, IVDMD and ruminal DMD, OMD and CPD can be enhanced by feeding Sesbania with Napier grass, and it can be used in diet mixtures up to 250 g/kg of the DM fed.

Nutritive value and aerobic stability of whole crop maize silage harvested at four stages of maturity

The effect of stage of maturity on the ensiling properties of whole crop maize was studied under laboratory conditions. Maize (Zea mays L.) was harvested at four maturity stages being, early dent (ED), one-third milkline (ML), two-thirds ML and blackline (BL). The chopped forages were ensiled in 1.5-l anaerobic jars. Three jars per treatment were sampled on days 2, 4, 8, 15, and 90. After 90 days of ensiling, the silages were subjected to an aerobic stability test lasting 5 days, in which CO 2 production was measured, as well as chemical and microbiological parameters. In addition, fibre content and in situ rumen degradability were analysed at the four stages of maturity. Water-soluble carbohydrates decreased in the silages with maturity. The silages from the ED stage had more lactic acid, ethanol, weight loss, yeast, and moulds than at one-third ML, two-thirds ML and BL stages. The silages from the ED stage produced more CO 2 than the one-third ML, two-thirds ML and BL stages ( P < 0.05). Silages from the ED stage were not judged to be stable under aerobic conditions. The fibre contents decreased in one-third ML, two-thirds ML and BL stage as compared with the ED stage ( P < 0.05). The neutral detergent fibre (NDF) content of silages decreased from 527 to 421 g/kg dry matter (DM) ( P < 0.05). The hemicellulose content did not change consistently throughout the growth period of the maize, but the crude protein (CP) content decreased in the BL stage as compared with the ED and one-third ML stages ( P < 0.05). The CP content decreased from 80 to 58 g/kg DM (P < 0.05). The highest in situ rumen DM and organic matters degradabilities, and degradable yields, were obtained at two-thirds ML stage. The highest NDF degradability was at the ED stage, but yields of degradable NDF were highest at two-thirds ML stage. Optimum whole crop maize harvest is at two-thirds ML stage to maximize yield of fermentable nutrients per hectare.

Rumen dry matter degradation of tree species by West African dwarf goats

AbstractRumen degradation of browse tree/shrubs was determined in West African dwarf goats. Gliricidia sepium, Baphia nitida and Afzelia bella were ranked as high; Newbouldia laevis and Alchornea cordifolia as medium; and Albizia zygia and Dialum guineense as low in forage quality. Copyright © 2004 Whurr Publishers Ltd

Effects of Amino Acids Fermentation By-product on Fermentation Quality and In situ Rumen Degradability of Italian Ryegrass (Lolium multiflorum) Silage

The experiment of silage for preservation of fresh Italian ryegrass (Lolium multiflorum) was carried out to examine whether the fermentation quality and microbial degradation in the rumen can be altered by the treatment of amino acids fermentation byproduct (AFB). The plant was ensiled for 40 days with 4 treatments of different ratios of AFB and sugarcane molasses (SCM) mixture. The treatment 2 (T2, AFB:SCM=100:0) and treatment 3 (T3, AFB:SCM=40:60) silages showed higher (p<0.05) concentrations of lactic acids, lower (p<0.05) pH and dry matter (DM) losses than the Control (T1, none additive) and treatment (T4, AFB:SCM=0:100) silages. The treatments 2 and 3 contained higher (p<0.05) DM and crude protein contents in silages compared to treatments 1 and 4 silages. The NDF, ADF and cellulose contents were also lower (p<0.05) in T2, T3 and T4 silages than T1 silage and fresh material before ensiled. The in situ rumen DM, NDF, ADF, hemicellulose and cellulose degradability was also higher (p<0.05) in T2, T3 and T4 silages than T1 silage, while the highest improvement was achieved with addition of AFB:SCM at level of 40:60 at ensiling. The result in this study indicates that the addition of AFB and SCM additives improved the silage fermentation and cell wall degradability of Italian ryegrass silage. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 5 : 633-637)

The Effect of Lactobacillus buchneri and Lactobacillus plantarum on the Fermentation, Aerobic Stability, and Ruminal Degradability of Low Dry Matter Corn and Sorghum Silages

The effect of Lactobacillus buchneri, alone or in combination with Lactobacillus plantarum, on the fermentation, aerobic stability, and ruminal degradability of low dry matter corn and sorghum silages was studied under laboratory conditions. The inoculants were applied at 1×106cfu/g. Silages with no additives served as control. After treatment, the chopped forages were ensiled in 1.5-L anaerobic jars. Three jars per treatment were sampled on d 2, 4, 8, 15, and 90. After 90 d of storage, the silages were subjected to an aerobic stability test lasting 5 d, in which CO2 production, as well as chemical and microbiological parameters, was measured to determine the extent of aerobic deterioration. At the end of the ensiling period (d 90), the L. buchneri- and L. buchneri + L. plantarum-inoculated silages had significantly higher levels of acetic acid than the control and L. plantarum-inoculated silages. Therefore, yeast activity was impaired in the L. buchneri- and L. buchneri + L. plantarum-inoculated silages. As a result, L. buchneri, alone or in combination with L. plantarum, improved aerobic stability of the low dry matter corn and sorghum silages. The combination of L. buchneri and L. plantarum reduced ammonia N concentrations and fermentation losses in the silages compared with L. buchneri alone. However, L. buchneri, L. plantarum, and a combination of L. buchneri + L. plantarum did not effect in situ rumen dry matter, organic matters, or neutral detergent fiber degradability of the silages. The L. buchneri was very effective in protecting the low dry matter corn and sorghum silages exposed to air under laboratory conditions. The use of L. buchneri, alone or in combination with L. plantarum, as a silage inoculant can improve the aerobic stability of low dry matter corn and sorghum silages by inhibition of yeast activity.

Analytical composition and rumen degradability of isogenic and transgenic corn varieties

AbstractTwo different corn cultivars were compared with their genetically modified counterparts containing the gene coding for the Cry1A(b) protein of Bacillus thuringiensis (Bt). There were no analytical differences between the conventional and transgenic genotype kernels, whereas stovers from Bt+ plants had higher sugar (148.3 g kg−1 versus 115.9 g kg−1; P &lt; 0.01) and lower NDF (592.7 g kg−1 versus 631.5 g kg−1; P &lt; 0.05) contents than Bt− maize. A comparison of the amino acid profiles showed higher phenylalanine content in kernels from the Bt+ plants (49.1 g kg−1 vs 47.8 g kg−1; P &lt; 0.05) which was, however, not reflected in the protein content. The initial dry matter rumen degradability of the isogenic kernels was higher than that of Bt+ varieties (569.5 g kg−1 vs 543.7 g kg−1; P &lt; 0.05), whereas the lower fibre content increased the dry matter (548.6 g kg−1 vs 526.6 g kg−1; P &lt; 0.01) and protein (695.6 g kg−1 vs 647.9 g kg−1; P &lt; 0.01) degradability after 24 h of incubation in stovers from Bt+ plants. The NDF degradability was higher in Bt− corn varieties because of the higher proportion of hemicellulose in the total fibre. Copyright © 2003 Society of Chemical Industry

Impact of level of spontaneous heating during storage of bermudagrass hay on rumen in situ disappearance kinetics in steers

Spontaneous heating reduces forage quality and nutrient digestibility in stored alfalfa ( Medicago sativa L.) and cool-season grasses. However, research describing the impact of spontaneous heating on disappearance kinetics of warm-season grasses is limited. Five crossbred ruminally cannulated steers were used in a randomized complete block design to determine the impact of spontaneous heating during the curing process on in situ disappearance kinetics of bermudagrass hay. Bermudagrass hays were baled at various moisture levels and bale densities that resulted in spontaneous heating that produced 5, 119, 201, 273, or 401 heating-degree days (HDD; >35 °C) during a 60-day storage period. Hays were evaluated for rumen dry matter (DM), neutral-detergent fiber (NDF), N, and neutral-detergent insoluble nitrogen (NDIN) disappearance kinetics. The immediately soluble DM fraction and effective ruminal DM disappearance generally decreased ( P<0.05) as HDD increased. The fraction of DM that disappeared at a measurable rate was lower ( P<0.05) in 5 HDD hays and the disappearance rate of DM ( K d) was faster ( P<0.05) from 5 and 119 HDD hays compared with forages subjected to higher HDD. The K d for NDF was faster ( P<0.05) from 5 and 119 HDD than from 201 and 273 HDD hays and effective NDF disappearance was higher ( P<0.05) from 5 and 119 HDD than from higher HDD hays. The K d for N was faster ( P<0.05) from 5 HDD, and effective N disappearance was greater ( P<0.05) from 5 and 119 HDD than from 201 or higher HDD. The K d for NDIN was faster ( P<0.05) from 5 and 119 HDD and effective NDIN disappearance was higher ( P<0.05) from 5, 119, and 201 HDD than from higher HDD hays. Moderate levels of spontaneous heating have negative effects on rate and effective ruminal disappearance of both DM and N in bermudagrass hay, thereby reducing the digestibility of DM and protein from heated forages.

The effect of ammoniated and roasted barley on rumen pH, milk yield and milk composition of lactating dairy cows

Cereal grains can provide the major source of energy in diets in order to meet the nutrient requirements of high producing dairy cows. However the amount of starch that can be included in the diets of dairy cows is limited particularly if starch is rapidly fermented such as barley starch. Reduction of feed intake, rumen pH, milk fat test, microbial growth and other metabolic disorders are expected if ruminally degradable starch is fed in amount that cant be efficiently metabolized by rumen microbs. Various techniques for processing barley grain have been developed to decrease the degradability of dry matter in rumen without reducing its extent of digestion. McNiven (1995) showed roasting of barley is more effective treatment. The objective of this experiment was to study of effects the roasting and ammoniation of barley grain on rumen pH, feces pH, milk yield and milk composition in dairy cows.

Use of animal and dietary information to predict rumen turnover

A database was developed from 16 scientific publications to explore mechanisms controlling rumen turnover. The database included 70 treatment means (43 cattle and 27 sheep) from experiments in which rumen contents were measured by complete manual evacuation or by slaughter. Rumen turnover was estimated as the ratio between rumen contents (kg of DM) and feed intake (kg of DM/h). Predictors were intake, body weight (BW), metabolic BW (BW 0.75), and the dietary components crude protein (CP), neutral detergent fiber (NDF), neutral detergent solubles (NDS), acid detergent lignin and ash. The best linear models obtained to predict rumen turnover ( T) for NDF, NDS, dry matter (DM) and acid detergent lignin (LIGN), respectively, were: T NDF =23.84−10.26 ln( D- NDFI); r 2:0.28,P<0.001 T NDS =17.08−13.39 ln( D- NDSI); r 2:0.76,P<0.001 T DM =20.16−10.14 ln( D- NDSI); r 2:0.65,P<0.001 T LIGN =37.69−30.77 ln( D- NDFI); r 2:0.70,P<0.001 These curvilinear relationships were likely due, at least for NDF and lignin, to the increase in rumen NDF content (% of BW) that occurred when intake of dietary, or forage, NDF (% of BW) increased. In the database, turnover of NDF and NDS showed additive behavior. No differences were found between cattle and sheep in rumen NDF, NDS and DM turnovers. When fed at the same level of intake of forage NDF (% of BW), sheep had significantly lower rumen NDF contents (% of BW) than cattle. The rumen evacuation technique is a valuable tool to explore interspecies relationships. The use of this large dataset derived from the scientific literature improved the understanding of the relationships existing among feed intake, body size and the components of rumen turnover, and allowed their quantification.

Rumen degradability and post-ruminal digestion of dry matter, nitrogen and amino acids in three tropical forage legumes estimated by the mobile nylon bag technique

The ruminal degradability and intestinal digestibility of dry matter (DM), nitrogen (N) and amino acids (AA) in whole plants of tropical forage legumes were estimated in three rumen and duodenal cannulated non-lactating Holstein/Friesian cows using the mobile nylon bag method. The legume samples were incubated in the rumen for 12, 24 and 48 h. After rumen incubation, the mobile bags were pre-incubated in pepsin–HCl solution before inserting into the duodenum and recovering in the faeces. Rumen DM degradabilities of cassia and of siratro were greater than that of lablab and increased with increasing rumen incubation time. The post-ruminal digestibility of undegraded DM was not different between the legumes. Similarly, N degradability was not different among the three legumes after similar incubation periods. However, the intestinal digestibility coefficients of rumen undegradable N in cassia and siratro were greater than that of lablab. The digestibility of total amino acids varied between 0.346 and 0.771. The digestibility coefficients of essential amino acids and non-essential amino acids followed a trend similar to that of total amino acids. Siratro showed the highest digestibilities of individual amino acids, total amino acids and nitrogen with cassia being intermediate and lablab the least. These results indicate that undegraded legume proteins differ as sources of absorbable amino acids in the small intestines.

Effect of herbage allowance on pasture utilization, regrowth and milk yield of dairy cows in early, mid and late season

The effect of herbage allowance (HA) on milk yield of dairy cows, pasture utilization and pasture regrowth was studied in a field trial conducted at the North Savo Research Station, Maaninka, Finland in 1998. The experiment was conducted with 24 lactating Holstein-Friesian cows that were strip-grazed on Phleum pratense L.– Festuca pratensis Huds. pastures. The pastures received 220 kg ha −1 N divided into three allocations and adequate amounts of P and K. The experiment was conducted as a replicated 3×3 Latin square design with three HA levels and three periods. The three HA levels were 19, 23 and 27 kg dry matter (DM) per cow per day (cut over 3 cm stubble height). The cows did not receive any supplements except minerals. Data were collected during three 10 days periods: mid-June, mid-July and beginning of August. Increasing HA decreased pasture utilization from 77.7 to 61.0%. Increasing HA increased post-grazing leaf area index (LAI) in each period, but the regrowth rate was similar for each treatment. The calculated energy-corrected milk (ECM) yield per hectare during the 15 days collection periods increased with decreasing HA from 2116 to 2406 and to 2808 kg ECM ha −1, respectively. The reduction in individual animal performance of 6% led to a 33% increase in animal production per area (i.e. HA 27 versus HA 19). A post-grazing sward height (SH) of 9–10 cm indicated an effective utilization of P. pratense L.– Festuca pratensis Huds. pastures. Increasing HA from 19 to 27 kg DM increased the milk yield by 0.16 kg ECM kg −1 ( P<0.01). HA had no effect on the milk composition. Milk yield decreased from 25.6 to 18.8 kg ECM ( P<0.01) when the grazing season advanced. HA had no effect on the rumen DM content ( P=0.58), instead, the rumen DM content increased from June to August ( P<0.01).

In sacco dry matter and nitrogen degradation and their relationship with in vitro dry matter digestibility of Napier grass (Pennisetum purpureum Schumach.) as influenced by height of plant at cutting

In vitro dry matter digestibility (IVDMD) as well as in sacco rumen dry matter degradability (DMD) and nitrogen degradability (ND) studies of Napier grass (Pennisetum purpureum) were carried out using a 3 3 factorial experiment arranged in a randomised complete block design with 3 replications. The treatments were 3 levels of nitrogen (N) fertiliser (0, 46, bacterium Synergistes jonesii is known to degrade these compounds and inoculation of the bacterium into the rumen protects cattle against mimosine and DHP toxicity. We report on the development, production, and storage of an in vitro, fermentor-based, mixed bacterial inoculum, which includes S. jonesii, for administration to cattle. This technique may be applicable to the production and delivery of other live, anaerobic, bacterial inocula for use in animal agriculture.

Ruminal Fermentation and Intestinal Flow of Nutrients by Lactating Cows Consuming Brown Midrib Corn Silages

Rumen characteristics and digestive kinetics of brown midrib corn silage were evaluated with five late-lactation (221 DIM±20 d) multiparous cows fitted with ruminal and duodenal cannula. Dietary treatments were applied by using a single reversal design with two 21-d periods where either brown midrib (BM3) or isogenic (ISO) corn silage were included in a total mixed ration formulated to be 40% concentrate and 60% corn silage on a dry matter (DM) basis. Rumen and total tract digestibilities of DM, organic matter, neutral detergent fiber, acid detergent fiber, starch, and N were determined and rumen characteristics evaluated. Apparent rumen DM and organic matter digestibilities were greater for the BM3 corn silage (7.1 and 4.7 percentage units, respectively). Dietary intake and duodenal flow of starch were greater and rumen and total tract starch digestibilities were lower for BM3 corn silage diets than ISO corn silage diets. However, more starch (1.1 kg/d) was apparently digested and absorbed postruminally in cows fed the BM3 corn silage diets. Duodenal flow of neutral detergent fiber was 0.9 kg/d lower, and ruminal (15.9 percentage units) and total tract digestibilities (4.4 percentage units) were higher for BM3 treatment compared with the ISO treatment. Digestive patterns of ADF were similar for the BM3 and ISO treatments. Ruminal pH was lower in the cows fed the BM3 corn silage than those fed the ISO corn silage. As a result of a tendency for decreased N excretion in urine and slight increases in N intake due to increased DM intake, N balance tended to be greater for the BM3 treatment compared with the ISO treatment. These results may partially explain the benefits of feeding BM3 corn silage to cows during early lactation, as the observed increases in fiber component digestibility and improved N economy may combine to enhance DM intake and better support the nutritional demands of milk production for the high producing dairy cow.

Strategies for Increasing Energy Density of Dry Cow Diets

The objective of this trial was to compare the effects of increasing dietary energy density from 1.51 to 1.65 Mcal/kg of dry matter (DM) by replacing forage with concentrate or by further increasing concentrate via the substitution of corn silage and alfalfa silage by a mixture of straw, starch, and soybean meal. Our hypothesis was that the latter diet would be more glucogenic while increasing rumen fill and be potentially desirable for transition cows. Nine far-off dry cows (greater than 3 wk before parturition at the end of the trial) were fed three diets: low energy diet, [LE, 1.51 Mcal/kg of DM, 14.0% crude protein (CP) and 35% nonfiber carbohydrates (NFC)], high energy diet, (HE, 1.65 Mcal/kg of DM, 13.9% CP and 39.5% NFC) and high energy diet, where a portion of alfalfa and corn silage was replaced by straw, soybean meal, and cornstarch (HES, 1.65 Mcal/kg of DM, 13.5% CP and 40.5% NFC). The experiment was a replicated 3 x 3 Latin square design with 21-d periods. Six cows from two squares were used to examine kinetics of DM disappearance from nylon bags suspended in the rumen. Two contrasts of interest were: LE versus HE, HES (effects of energy density) and HE versus HES (method of increasing energy density). Increasing energy density increased the potentially degradable (B) and decreased the undegradable (C) DM fractions of the diets. Because HES had greater B and a faster rate of degradation of fraction B (k), effective rumen degradable DM (ERDDM) was higher in HES compared to HE. Cows fed high energy diets had greater DM intake. No differences in DM intake were observed between HE and HES. Rumen volume or DM pool sizes were not affected by treatment. High energy diets increased total ruminal fluid volatile fatty acid concentration compared with LE. Propionate concentration was higher in cows fed high energy diets compared with cows fed LE. The partial replacement of alfalfa and corn silage by straw, soybean meal, and cornstarch further increased propionate concentration. The greatest increase in serum insulin concentration following feeding was observed in cows fed HE. Cows consuming high energy diets had lower plasma nonesterified fatty acids (NEFA) before and after feeding. The HES diet was less effective in decreasing plasma NEFA concentration after feeding compared to HE. In conclusion, increasing diet energy density of far-off dry cows positively affected DMI, ruminal propionate, serum insulin, and plasma NEFA. Increasing energy density with a blend of feeds that represent extremes in rates of carbohydrate fermentation may be a strategy to provide greater amounts of glucogenic precursors. Applicability of this strategy should be examined in transition cows.

Effect of feeding frequency on bacterial and fungal concentrations, pH, and other parameters in the rumen.

Three sheep were fed a pelleted high-roughage diet either once, 6, or 24 times per day in a 3 x 3 Latin square trial. During each 21-d period, 14 d were allowed for adaptation followed by a 7-d collection period, in which samples for microbial counts were taken on d 1 and 5 and several rumen parameters were measured on d 2 and 6. Bacterial concentrations were not different between feeding frequencies on the first sampling day but were higher (P < 0.05) on the second sampling day when the sheep were fed 24 times a day. Fungal concentrations were not different among feeding frequencies on either sampling day. No effects of feeding frequency were observed for the concentration of cellulolytic bacteria or fungi. On d 2, ruminal volume was larger (P < 0.05) with six feedings than with one feeding and fluid volume turnover was greater (P < 0.05) when sheep were fed 24 times per day. Rumen pH values were higher (P < 0.01) on both d 1 and 5 when the sheep were fed once a day and the percentage of rumen dry matter was highest (P < 0.02) with 24 feedings. These findings would suggest that if the same amount of a given diet is fed daily, the number of feedings does not markedly affect microbial concentrations, rumen volume, or liquid turnover time.