Acid Detergent Fiber Disappearance Research Articles

The Effect of Different Lactic Acid Bacteria Inoculants on Silage Quality, Phenolic Acid Profiles, Bacterial Community and In Vitro Rumen Fermentation Characteristic of Whole Corn Silage

Corn silage is an important source of forage, but whether or not bacterial inoculants should be applied is somewhat controversial in ruminant feeding practice. In the present study, chopped whole corn plants treated with a single inoculant of Lactobacillus buchneri (LB), Lactobacillus plantarum (LP), Pediococcus pentosaceus (PP) served as either homofermentation (e.g., lactate only) or heterofermentation (e.g., lactate and acetate) controls and compared with those treated with either a mixture of the lactic acid bacteria (QA: 60% LP, 10%PP, 30% LB) or a mixture of the lactic acid bacteria (QB: 60% LP, 15% PP, 25% LB), to investigate their effects on the fermentation quality, ester-linked phenolic acids, and in vitro digestibility. After 60 day ensiling, the addition of QA exhibited the lowest pH (3.51) with greater lactic acid (LA) production. The ester-linked ferulic acid (FAest) and p-coumaric acid (pCAest) concentrations were significantly decreased during 60 days ensiling. And among all these groups, the LB and QA treated group showed a lower concentration of FAest and pCAest than other groups. After 60 days ensiling, Lactobacillus was the dominant genus in all LAB treated groups. Meanwhile, negative correlations of Bacillus, Bacteroides, Bifidobacterium, Blautia, Prevotella, Ruminococcus, and Roseburia with FAest content after 60 days ensiling occurred in the present study. Komagataeibacter was mainly found in LB and PP addition silages, and presented a significant negative effect with the level of acid detergent fiber (ADF). To explore whether the addition of LABs can improve digestibility of whole corn silage, an in vitro rumen fermentation was conducted using the 60 day ensiled whole corn silages as substrates. The QA addition group exhibited a greater 48 h and 96 h in vitro dry matter and ADF disappearance, greater 48 h gas production and less methane emissions. Even though there were the same neutral NDF levels in corn silages treated with LB and QA after 60 days ensiling, the QA treated silages with lower FAest and pCAest presented higher IVDMD after 96 h and 48 h in vitro fermentation. In brief, the addition of mixed inoculants of 60% LB,10% PP, 30% LB compared with the addition of whichever single HoLAB or HeLAB inoculants, facilitated the release of ester-linked phenolic acids (e.g., ferulic and p-coumaric acids) and remarkably, improved silage quality in terms of sharp pH decline and greater lactate production. Taken together with the improvement in rumen microbial fermentation, the results obtained in the present study provided concrete evidence for the role of mixed LAB application in corn silage preparation for ruminant feeding practices.

In vitro acid detergent fibre (ADF) disappearance of brewery waste incorporated paddy straw in RUSITEC

An in vitro experiment was conducted to study the in vitro ADF disappearance of the following seven experimental feeds such as 1) Control feed; 2) Experimental feed (75%) + Fresh brewery waste (25%) (EFFBW); 3) Experimental feed (75%) + Dried brewery waste (25%) (EFDBW); 4) Fresh brewery waste (FBW); 5) Dried brewery waste (DBW); 6) Paddy straw (PS) and 7) Brewery waste incorporated paddy straw (BWIPS) incubated for 2, 6, 12, 24, 48 and 72 hours in Rumen Simulation Technique (RUSITEC). During initial incubation periods (2, 6, 12 and 24 hours), the control feed, EFFBW, EFDBW and FBW showed higher in vitro ADF disappearance than other experimental feeds, whereas, during later incubation periods (48 and 72 hours), the DBW, paddy straw and BWIPS showed higher in vitro ADF disappearance than other experimental feeds incubated in RUSITEC. Among the feeds experimented in RUSITEC, disappearance was more in the control feed, EFFBW and EFDBW when compared to other experimental feeds. Similarly, the disappearance was more in BWIPS compared to paddy straw. The in vitro ADF disappearance rates at all incubation periods were higher for FBW than those for DBW.

Addition of polyvinyl alcohol (PVA) to lactated Ringer’s solution (LRS) prevents equine embryos from adhering to plastic search dishes after initial recovery

To assess the impact of protein on fermentation by equine cecal microorganisms, cecal fluid from 4 cecally cannulated horses was used to inoculate fermentation bottles containing buffer, forage, and supplemental protein. In experiment 1, sodium caseinate (SC) provided 0, 0.5%, 1%, 2%, or 4% additional crude protein (CP) to bottles containing alfalfa or native warm-season prairie grass hay. Bottles were equipped with continuous gas pressure monitors and placed into a shaking incubator for 48 hours at 39°C. Cultures with alfalfa had greater (P < .0001) in vitro dry matter disappearance (IVDMD), neutral detergent fiber disappearance (NDFD), acid detergent fiber disappearance (ADFD), cumulative gas production, and total volatile fatty acid (VFA). Sodium caseinate increased gas production (P ≤ .05) and decreased pH (P < .003) in cultures with grass hay. Sodium caseinate at 1%, 2%, or 4% additional CP increased IVDMD, NDFD, and ADFD (P < .01), while 4% additional CP also increased total VFA (P < .01). For experiment 2, SC, fishmeal, soybean meal (SBM), whey, porcine blood plasma, and L-lysine hydrochloride were added to supply 2% additional CP to cultures with grass hay. All protein sources decreased pH and increased IVDMD, NDFD, and ADFD (P ≤ .01), with the largest effects elicited by SC, L-lysine, and whey (P ≤ .05). Total VFA (P ≤ .04) and gas (P ≤ .05) production increased with L-lysine, whey, SC, SBM, and fishmeal. While protein supplementation had minimal effects on cultures containing alfalfa, it altered fermentation of grass hay, more notably with more soluble protein sources.

Effects of Sodium Caseinate and Varying Protein Sources on In Vitro Fermentation of Forages by Mixed Equine Cecal Microorganisms

To assess the impact of protein on fermentation by equine cecal microorganisms, cecal fluid from 4 cecally cannulated horses was used to inoculate fermentation bottles containing buffer, forage, and supplemental protein. In experiment 1, sodium caseinate (SC) provided 0, 0.5%, 1%, 2%, or 4% additional crude protein (CP) to bottles containing alfalfa or native warm-season prairie grass hay. Bottles were equipped with continuous gas pressure monitors and placed into a shaking incubator for 48 hours at 39°C. Cultures with alfalfa had greater (P < .0001) in vitro dry matter disappearance (IVDMD), neutral detergent fiber disappearance (NDFD), acid detergent fiber disappearance (ADFD), cumulative gas production, and total volatile fatty acid (VFA). Sodium caseinate increased gas production (P ≤ .05) and decreased pH (P < .003) in cultures with grass hay. Sodium caseinate at 1%, 2%, or 4% additional CP increased IVDMD, NDFD, and ADFD (P < .01), while 4% additional CP also increased total VFA (P < .01). For experiment 2, SC, fishmeal, soybean meal (SBM), whey, porcine blood plasma, and L-lysine hydrochloride were added to supply 2% additional CP to cultures with grass hay. All protein sources decreased pH and increased IVDMD, NDFD, and ADFD (P ≤ .01), with the largest effects elicited by SC, L-lysine, and whey (P ≤ .05). Total VFA (P ≤ .04) and gas (P ≤ .05) production increased with L-lysine, whey, SC, SBM, and fishmeal. While protein supplementation had minimal effects on cultures containing alfalfa, it altered fermentation of grass hay, more notably with more soluble protein sources.

55 The influence of kudzu (Pueraria montana var. lobata) age on in situ rumen degradation

Abstract Early and late season kudzu (Pueraria montana var. lobata) leaves were collected to analyze dry matter (DM), crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) in situ rumen disappearance to assess kudzu quality. Four studies were conducted during different growing seasons [2 repeated early season (ES); 2 repeated late season (LS) to determine age variability effects. Kudzu collected from 7 middle Tennessee counties were incubated in the rumen for designated lengths of time (0.25, 1, 12, 24, 36, 48, and 72 h) to determine total rumen degradation (%) and rate of disappearance (% / h). Data were analyzed as a randomized complete block design (RCBD) with repeated measures. Regression analysis was used to determine degradation rate. Overall season effects (across incubation times) for dry matter disappearance (DMD) were significantly different (P &lt; 0.0001). Significant season by incubation time interactions were exhibited for total DMD at 12 (P &lt; 0.0001), 24 (P = 0.0004), 36 (P = 0.0055), 48 (P = 0.0209), and 72 h (P = 0.0384) incubation, with an average rumen degradability of ES kudzu being 9.75% higher than LS between 12 and 72 h. Slope regression between 1 and 24 h determined a rumen degradation rate of 2.41% / h across both seasons, with no significant seasonal difference (P = 0.3396). These results are indicative that ES kudzu is more highly rumen degradable than LS, as evidenced by the significant season by incubation time interactions between 12 and 72 h of incubation. Although there are significant seasonal effects on kudzu DMD during certain incubation times, DMD overall for ES and LS is still indicative of high rumen degradability with an average of 81.45% at 72 h across both seasons. Season effects were minimal for NDF, ADF, and CP rumen disappearance.

148 The influence of kudzu (Pueraria montana var. lobata) age on in situ rumen degradation

Abstract Early and late season kudzu (Pueraria montana var. lobata) leaves were collected to analyze dry matter (DM), crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) in situ rumen disappearance to assess kudzu quality. Four studies were conducted during different growing seasons [2 repeated early season (ES); 2 repeated late season (LS) to determine age variability effects. Kudzu collected from 7 middle Tennessee counties were incubated in the rumen for designated lengths of time (0.25, 1, 12, 24, 36, 48, and 72 h) to determine total rumen degradation (%) and rate of disappearance (% / h). Data were analyzed as a randomized complete block design (RCBD) with repeated measures. Regression analysis was used to determine degradation rate. Overall season effects (across incubation times) for dry matter disappearance (DMD) were significantly different (P &lt; 0.0001). Significant season by incubation time interactions were exhibited for total DMD at 12 (P &lt; 0.0001), 24 (P = 0.0004), 36 (P = 0.0055), 48 (P = 0.0209), and 72 h (P = 0.0384) incubation, with an average rumen degradability of ES kudzu being 9.75% higher than LS between 12 and 72 h. Slope regression between 1 and 24 h determined a rumen degradation rate of 2.41% / h across both seasons, with no significant seasonal difference (P = 0.3396). These results are indicative that ES kudzu is more highly rumen degradable than LS, as evidenced by the significant season by incubation time interactions between 12 and 72 h of incubation. Although there are significant seasonal effects on kudzu DMD during certain incubation times, DMD overall for ES and LS is still indicative of high rumen degradability with an average of 81.45% at 72 h across both seasons. Season effects were minimal for NDF, ADF, and CP rumen disappearance.

Effects of red clover isoflavones on tall fescue seed fermentation and microbial populations in vitro.

Negative impacts of endophyte-infected Lolium arundinaceum (Darbyshire) (tall fescue) are responsible for over $2 billion in losses to livestock producers annually. While the influence of endophyte-infected tall fescue has been studied for decades, mitigation methods have not been clearly elucidated. Isoflavones found in Trifolium pratense (red clover) have been the subject of recent research regarding tall fescue toxicosis mitigation. Therefore, the aim of this study was to determine the effect of ergovaline and red clover isoflavones on rumen microbial populations, fiber degradation, and volatile fatty acids (VFA) in an in vitro system. Using a dose of 1.10 mg × L-1, endophyte-infected or endophyte-free tall fescue seed was added to ANKOM fiber bags with or without 2.19 mg of isoflavones in the form of a control, powder, or pulverized tablet, resulting in a 2 × 3 factorial arrangements of treatments. Measurements of pH, VFA, bacterial taxa, as well as the disappearance of neutral detergent fiber (aNDF), acid detergent fiber (ADF), and crude protein (CP) were taken after 48 h of incubation. aNDF disappearance values were significantly altered by seed type (P = 0.003) and isoflavone treatment (P = 0.005), and ADF disappearance values were significantly different in a seed × isoflavone treatment interaction (P ≤ 0.05). A seed × isoflavone treatment interaction was also observed with respect to CP disappearance (P ≤ 0.05). Eighteen bacterial taxa were significantly altered by seed × isoflavone treatment interaction groups (P ≤ 0.05), eight bacterial taxa were increased by isoflavones (P ≤ 0.05), and ten bacterial taxa were altered by seed type (P ≤ 0.05). Due to the beneficial effect of isoflavones on tall fescue seed fiber degradation, these compounds may be viable options for mitigating fescue toxicosis. Further research should be conducted to determine physiological implications as well as microbiological changes in vivo.

Effects of gallic acid on in vitro rumen fermentation and methane production using rumen simulation (Rusitec) and batch-culture techniques

Two experiments were conducted to investigate the effects of adding gallic acid (GA) to ruminant diets on long- and short-term in vitro rumen fermentation and methane (CH4) production, and to test possible interactions between GA and ethanol on fermentation. The first experiment was conducted using the rumen simulation technique (Rusitec), as a completely randomised block design with four replications and the following four doses of GA: 0, 5, 10 and 20 mg GA/g dry matter (DM). Ethanol was used in all treatments to increase the solubilisation of GA in rumen fluid. The experimental period lasted 16 days, of which the first 7 days were for adaptation and the subsequent 9 days were for sampling. The second experiment was a 48-h batch-culture incubation conducted as a completely randomised design with a 4 (GA dose; 0, 10, 20, and 40 mg GA/g DM) × 2 (with or without ethanol) arrangement of treatments. In the Rusitec experiment, addition of GA up to 20 mg/g DM did not affect DM disappearance (DMD), organic matter (OM) disappearance, neutral detergent-fibre disappearance (NDFD), acid detergent-fibre disappearance (ADFD) or starch disappearance (P &amp;gt; 0.05), but crude protein disappearance was linearly decreased (P = 0.04) from 78.3% to 72.0%. Daily gas production and CH4 production expressed as mL/g DM and mL/g DMD were not affected by addition of GA (P &amp;gt; 0.05). Addition of GA up to 20 mg/g DM increased butyrate and isovalerate production (P &amp;lt; 0.05) and tended to increase isobutyrate (P = 0.09) and decrease heptanoate production (P = 0.07). In the batch-culture experiment, adding GA up to 40 mg/g DM linearly increased 48-h DMD, NDFD and ADFD (P &amp;lt; 0.05) and decreased (P &amp;lt; 0.05) CH4 expressed as mL/g DMD, mL/g NDFD and mL/g ADFD. Methane production was decreased after 24 h and 48 h only when GA was added at 10 mg/g DM without ethanol. Fermentation liquid pH and concentration of ammonia-nitrogen (ammonia-N) were also reduced (P &amp;lt; 0.05) with an increasing concentration of GA. Treatments with ethanol notably enhanced 48-h DMD, NDFD, ADFD, gas production (mL/g DM, mL/g OM or mL/g DMD), CH4 production (mL/g DM, mL/g DMD or mL/g NDFD), total volatile fatty acid concentration, the acetate:propionate ratio, acetate, valerate, isovalerate and caproate molar proportions (P &amp;lt; 0.01) and decreased propionate, butyrate and isobutyrate molar proportions (P &amp;lt; 0.01). Significant dose of GA × ethanol interaction was observed only for acetate molar proportion (P = 0.03). In conclusion, our study suggests that the beneficial effects of GA on feed digestion and CH4 production may be short term, while improvements in N metabolism may be sustained over the long term. It may be useful to conduct long-term in vivo studies using a range of diets and doses to verify whether GA can be used as a feed additive to mitigate enteric CH4 production and improve N metabolism of ruminants.

Effects of Synbiotics Containing Anaerobic Microbes and Prebiotics on In vitro Fermentation Characteristics and In situ Disappearance Rate of Fermented-TMR

This study was carried out to estimate effects of synbiotics containing anaerobic microorganisms and prebiotics on in vitro fermentation characteristics and in situ disappearance rate of fermented total mixed ration (F-TMR). For the in vitro trial, ninety vinyl bags were prepared to analyze temperature, pH, ammonia concentration, microbial growth rate and short chain fatty acid concentration. For the in situ trial, one hundred twenty nylon bags were prepared to analyze dry matter (DM), acid detergent fiber (ADF) and neutral detergent fiber (NDF) disappearance rate. Treatments consisted of a basal diet (US) with prebiotics and probiotics from anaerobic mold (MS), bacteria (BS), yeast (YS) or compound (CS). It was found that temperatures at 14 and 21 days were significantly higher (p<0.05) in the YS and CS than in the others. The pH at 21 days was lower in the CS than in the US. The synbiotic treatments had significantly increased (p<0.05) ammonia concentration at 21 days. The DM disappearance at 72 h was significantly higher (p<0.05) in the MS and CS than in the others. ADF and NDF disappearance rate tended to increase at a rate similar to the DM disappearance rate. Therefore, this study suggests that synbiotics (probiotics with prebiotics) may partially help the quality of fermentation and digestibility

Effects of essential oils on rumen fermentation, milk production, and feeding behavior in lactating dairy cows

Seven ruminally cannulated lactating Holstein dairy cows were used in an incomplete Latin rectangle design to assess the effects of 2 commercial essential oil (EO) products on rumen fermentation, milk production, and feeding behavior. Cows were fed a total mixed ration with a 42:58 forage:concentrate ratio (DM basis). Treatments included addition of 0.5 g/d of CE Lo (85mg of cinnamaldehyde and 140mg of eugenol), 10 g/d of CE Hi (1,700mg of cinnamaldehyde and 2,800mg of eugenol), 0.25 g/d of CAP (50mg of capsicum), or no oil (CON). Cows were fed ad libitum twice daily for 21 d per period. Dry matter intake, number of meals/d, h eating/d, mean meal length, rumination events/d, h ruminating/d, and mean rumination length were not affected by EO. However, length of the first meal after feeding decreased with addition of CE Hi (47.2min) and CAP (49.4min) compared with CON (65.4min). Total volatile fatty acids, individual volatile fatty acids, acetate:propionate ratio, and ammonia concentration were not affected by EO. Mean rumen pH as well as bouts, total h, mean bout length, total area, and mean bout area under pH 5.6 did not differ among treatments. Total tract digestibility of organic matter, dry matter, neutral detergent fiber, acid detergent fiber, crude protein, and starch were not affected by EO. Milk yield and composition did not change with EO. In situ dry matter disappearance of ground soybean hulls was not affected by EO. However, organic matter disappearance of soybean hulls with CE Hi tended to decrease compared with CON. Compared with CON, neutral detergent fiber disappearance (41.5 vs. 37.6%) and acid detergent fiber disappearance (44.5 vs. 38.8%) decreased with addition of CE Hi. The CE Lo had no effect on rumen fermentation, milk production, or feeding behavior but CAP shortened the length of the first meal without changing rumen fermentation or production, making it a possible additive for altering feeding behavior. The CE Hi negatively affected rumen fermentation and shortened the length of the first meal, suggesting that a dose of 10 g/d is not beneficial to lactating dairy cows.

Improved milk production efficiency in early lactation dairy cattle with dietary addition of a developmental fibrolytic enzyme additive

A 3-part study was conducted to evaluate the effect of a developmental fibrolytic enzyme additive on the digestibility of selected forages and the production performance of early-lactation dairy cows. In part 1, 4 replicate 24-h batch culture in vitro incubations were conducted with alfalfa hay, alfalfa silage, and barley silage as substrates and ruminal fluid as the inoculum. A developmental fibrolytic enzyme additive (AB Vista, Marlborough, UK) was added at 5 doses: 0, 0.5, 1.0, 1.5, and 2.0 μL/g of forage dry matter (DM). After the 24-h incubation, DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) disappearance were determined. For alfalfa hay, DM, NDF, and ADF disappearance was greater at the highest dosage compared with no enzyme addition. Barley silage NDF and ADF and alfalfa silage NDF disappearance tended to be greater for the highest enzyme dosage compared with no enzyme addition. In part 2, 6 ruminally cannulated, lactating Holstein dairy cows were used to determine in situ degradation of alfalfa and barley silage, with (1.0 mL/kg of silage DM) and without added enzyme. Three cows received a control diet (no enzyme added) and the other 3 received an enzyme-supplemented (1.0 mL/kg of diet DM) diet. Enzyme addition after the 24h in situ incubation did not affect the disappearance of barley silage or alfalfa silage. In part 3, 60 early-lactation Holstein dairy cows were fed 1 of 3 diets for a 10-wk period: (1) control (CTL; no enzyme), (2) low enzyme (CTL treated with 0.5mL of enzyme/kg of diet DM), and (3) high enzyme (CTL treated with 1.0mL of enzyme/kg of diet DM). Adding enzyme to the diet had no effect on milk yield, but dry matter intake was lower for the high enzyme treatment and tended to be lower for the low enzyme treatment compared with CTL. Consequently, milk production efficiency (kg of 3.5% fat-corrected milk/kg of DM intake) linearly increased with increasing enzyme addition. Cows fed the low and high enzyme diets were 5.3 (not statistically significant) and 11.3% more efficient, respectively, compared with CTL cows. This developmental fibrolytic enzyme additive has the potential to increase fiber digestibility of forages, which could lead to greater milk production efficiency for dairy cows in early lactation.

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.

Degradabilidade ruminal da matéria seca, da fração fibrosa e da proteína bruta de forrageiras

O objetivo deste trabalho foi avaliar a degradabilidade ruminal da matéria seca, da fibra em detergente neutro, da fibra em detergente ácido e da proteína bruta da alfafa (Medicago sativa), aveia-preta (Avena strigosa), leucena (Leucaena leucocephala) e guandu (Cajanus cajan). Amostras de 3 g das forragens foram incubadas no rúmen de três novilhos por períodos de 0, 6, 12, 24, 36, 48 e 72 horas. As degradabilidades efetivas da matéria seca da alfafa e da aveia, para a taxa de passagem de 5% por hora, foram elevadas (acima de 60%). A leucena e o guandu apresentaram valores inferiores, 50,9 e 56,0%, respectivamente. A partir de 24 horas de incubação, a aveia se destacou com maior desaparecimento da fibra em detergente neutro e da fibra em detergente ácido, e ainda apresentou as mais elevadas taxas de degradação efetiva destas frações. A aveia foi a forragem que apresentou maior degradabilidade da matéria seca, da fibra em detergente neutro, da fibra em detergente ácido e da proteína bruta no rúmen. O guandu, entretanto, foi a forragem com as piores taxas de degradação.

Influence of disodium malate on microbial growth and fermentation in rumen-simulation technique fermenters receiving medium- and high-concentrate diets

Two incubation trials were carried out with the rumen-simulation technique (RUSITEC). In each trial, four vessels received a diet of grass hay and concentrate (600 and 400 g/kg DM, respectively; diet F), and the other four were fed a diet composed of concentrate and barley straw (900 and 100 g/kg DM, respectively; Diet C). Vessels were given 20 g of the corresponding diet daily, and half of them were supplemented with disodium malate to achieve a final concentration of 6.55 mM. There were no effects (P>0.05) of malate either on pH or on the daily production of NH3-N, but malate treatment increased (P<0.05) DM, neutral detergent and acid detergent fibre disappearance after 48 h incubation. The daily production of propionate and butyrate increased (P<0.001), and the ratio CH4:volatile fatty acids decreased (P<0.001) by supplementing both diets with malate. Whereas adding malate to the F diet produced an increase in acetate production (P=0.011) and the growth of solid-associated micro-organisms (P=0.037), no effects (P>0.05) were observed for diet C. For both diets, there were no differences (P>0.05) between treatments in the daily flow of liquid-associated micro-organisms measured using (15)N as a microbial marker. These results indicate that malate stimulated the in vitro fermentation of both diets by increasing the apparent disappearance of the diet and decreasing the ratio of CH4:volatile fatty acids, but a greater response was observed with diet F. If these results are confirmed in vivo, malate could be used as a feed additive for ruminants fed diets containing medium proportions of forage (i.e. dairy animals) and not only in animals fed high-concentrate diets, as has so far been proposed.

Efeito de sementes oleaginosas inteiras e óleo de soja sobre a digestibilidade in vitro e os padrões ruminais de bezerros holandeses

Este trabalho foi realizado para comparar os efeitos da adição de sementes inteiras de soja e algodão e de óleo de soja sobre os padrões ruminais e a digestibilidade in vitro, em bezerros Holandeses fistulados. Dois bezerros fistulados no rúmen foram alimentados com dieta basal com 2,5% de extrato etéreo (EE), o qual foi comparado com dietas com 5,0% de EE, em que as sementes de soja e algodão inteira ou o óleo de soja foram fontes de EE adicional. A adição de sementes de soja e de algodão resultou em decréscimo na digestibilidade in vitro da matéria seca e da fibra em detergente neutro (FDN), porém não houve alterações na digestibilidade in vitro da fibra em detergente ácido (FDA) em relação à dieta controle. A adição de semente algodão provocou decréscimo na digestibilidade in vitro da proteína bruta em comparação à dieta controle. A concentração de ácido propiônico nas dietas com adição de óleo de soja foi 16% mais elevada que a proporcionada pelas demais dietas. O uso de óleo de soja pareceu ser a mais adequada em relação à digestibilidade da matéria seca, FDA e FDN e à manutenção de pH, quando comparado a outros tipos de adição lipídica, porém menos eficiente que a semente de soja em relação à digestibilidade in vitro da proteína bruta. O número de protozoários apresentou grande variação entre dietas, mas nenhum efeito com adição de óleo foi observado. A maior concentração de N-NH3 ruminal foi obtida na dieta com óleo de soja, quando comparada às outras dietas.

Ruminal degradation characteristics of corn and corn–sunflower intercropped silages prepared at two stages of maturity

The degradation characteristics of dry matter (DM), protein, neutral detergent fiber (NDF) and acid detergent fiber (ADF) of corn–sunflower intercrop silage (CSS) and monoculture corn silage (CS) prepared from whole plants, harvested at two stages of maturity, were compared using eight mature rumen-cannulated steers. The degradation characteristics were determined by incubating the silages in nylon bags for up to 72 h in the rumen of animals fed the respective silages. The degradation characteristics determined for the silages were the soluble fraction, the insoluble but degradable fractions, the rate of degradation of the degradable fractions of silage DM and protein, and the in situ disappearance of NDF and ADF after 0.5 and 72 h of incubation. The rate of particulate passage from the rumen was determined using chromium-mordanted NDF of the four silages. Values were used to estimate effectively degraded DM and protein. The rates of DM and protein degradation were highest for late-cut CSS (6.3 and 6.0% h−1, respectively) and the least for late-cut CS (2.5 and 0.8% h−1, respectively). Averaged across stages of maturity, more (P &lt; 0.05) DM and protein were effectively degraded with CSS (57.4 and 70.1%, respectively) than with CS (48.8 and 48.7%). Degradation of NDF in early-cut CSS was lower (P &lt; 0.05) than in CS after 72 h of incubation. ADF disappearance from all of the silages after 72 h of incubation was similar. Ruminal degradation of DM and protein in CSS was greater than in CS, which may affect efficiency of utilization of CSS. Key words: Degradation rate, effective degradability, corn silage, intercropped corn–sunflower, steers

Composition and fibre digestion in morphological components of an alfalfa-timothy sward

Forage intake in ruminants varies with the species and morphology of the plant and is related to the content of fibre and the rate and extent of its digestion in the rumen. Herbage was collected from an established sward of alfalfa ( Medicago sativa L.) and timothy ( Phleum pratense L.) and separated into leaf and stem fractions. Alfalfa leaf and stem were further divided by removing the five terminal internodes > 10 mm from each shoot. Leaf of both species was higher in nitrogen (N), dry matter disappearance in vitro and in fibre constituents, including neutral detergent fibre (NDF), acid detergent fibre (ADF), cellulose, hemicellulose and acid detergent lignin (ADL). Disappearance of NDF from leaves from the upper portion of alfalfa shoots was 632 g kg −1, compared with 796 g kg −1 for timothy leaf. Lower alfalfa stem NDF had a disappearance of 311 g kg −1 NDF and timothy stem had 474 g kg −1. In spite of this difference, the two fractions had the same amount of undigested NDF remaining after 12 h of incubation. This was caused by a higher rate of digestible NDF disappearance in alfalfa stem than in timothy stem. Alfalfa leaf fractions also had higher rates of NDF disappearance than timothy leaf. Digestible ADF disappearance rates were similar in the two species, except that the rate for the lower alfalfa stem component was 12.8% h −1 while the rate for timothy stem was 8.0% h −1. Timothy leaf had higher rates of cellulose and hemicellulose disappearance than alfalfa leaf. Lower stem of alfalfa had the lowest cellulose and hemicellulose disappearance. Results of this experiment indicate that preferential consumption of leaf over stem or legume over grass would in general provide a diet lower in NDF, lower in indigestible NDF and with a higher rate of NDF disappearance.

Characterization of in situ nitrogen and fiber digestion and bacterial nitrogen contamination of hay crop forages preserved at different dry matter percentages.

Alfalfa, red clover, orchardgrass and timothy were harvested in the vegetative stage, wilted and stored as hay, or ensiled in small batch silos (20 kg) at 60, 40 or 20% (direct cut) dry matter and were analyzed for compositional differences. A ruminally cannulated lactating cow, consuming 50% of her dry matter intake from hay crop silage, was used to measure in situ dry matter, N, neutral detergent fiber and acid detergent fiber disappearance. Diaminopimelic acid was used as a bacterial marker to correct for bacterial N contamination for in situ residual N. Fibrous components tended to become concentrated as percent dry matter at preservation decreased, presumably associated with leaching of water solubles during storage. For most forages, as dry matter percentage of preservation decreased, water soluble dry matter and N increased, with a concomitant increase of ruminally nondigested dry matter. Specific trends in coefficients of digestion associated with forage type or preservation dry matter percentage were not observed for dry matter, N, neutral detergent fiber or acid detergent fiber. Correction for contamination by bacterial N decreased lag time in digestion and altered rates of N digestion compared with noncorrected rates. Linear and quadratic bacterial N contamination profiles were observed with time of ruminal incubation. Rate of digestion of N was highly correlated with fibrous component concentration, and to a lesser extent to rate of neutral and acid detergent fiber digestion. Dry matter percentage at preservation had a variable effect on ruminal digestion rate of dry matter and N, which varied with forage type and had no effect on neutral detergent and acid detergent fiber digestion rates. Correction for bacterial N contamination should be considered when establishing N digestion rates for forage by the in situ technique.

Influence of feed intake level on site of digestion in steers fed a high concentrate diet.

A high concentrate diet was fed at 1.2, 1.5, 1.8 and 2.1% of body weight to four Angus steers (258 kg) equipped with cannulas in the proximal duodenum and distal ileum. As level of feed intake increased, flow of N, nonammonia N, microbial N and feed N to the small intestine increased linearly (P less than .05). Bypass of feed N increased from 44 to 71% of fed N. At the highest intake level, ruminal protein degradation and protein solubility were almost equal. At lower intake levels, feed protein degradation exceeded N use by microbes, but at the higher level of intake, microbial protein synthesis exceeded N available from protein degradation. Microbial efficiency increased as feed intake was increased to 1.8% of body weight. Apparent digestion of N in the small intestine increased with feed intake. Starch digestion in the rumen increased slightly with feed intake while organic matter and acid detergent fiber (ADF) digestibility declined. At the highest level of feed intake, no ADF disappearance occurred in the rumen. Results suggest that level of feed intake markedly alters 1) bypass and supply of intestinally digested protein, 2) need for degradable N in the rumen, 3) efficiency of microbial growth and 4) ruminal fiber digestion. Both retention time and contingent characteristics of fermentation in the rumen appear to be involved in these alterations.