In vitro efficiency of combined acid-heat treatments for protecting sunflower meal proteins against ruminal degradation

Efficacy of combined acid-heat treatments to protect crude protein (CP) against ruminal degradation has not been extensively researched. Four in vitro trials (Daisy technology) with orthophosphoric and malic acids were performed to examine effects on protection of sunflower meal protein. In Trial 1, effects of the solution volume for adding two doses of orthophosphoric acid (0.4 and 1.2 eq/kg sunflower meal) were tested using five dilution volumes (80, 160, 240, 320 and 400 ml/kg of feed) for each acid dose. Samples were heated at 60°C. The quantity of CP that remained undegraded after 20 h in vitro (IVUCP) increased with the amount of acid added (P = 0.01). Increasing the dilution volume also tended (P = 0.065) to increase IVUCP. Therefore, a dilution volume of 400 ml/kg was employed in all further trials. In Trial 2, treatments with solutions of orthophosphoric and malic acids (1.2, 2.4, 3.6 and 4.8 eq/kg) and 60°C of drying temperature were used. Increased CP protection with increased acid doses was described. In this and further trials, higher protective effects of malic acid than orthophosphoric acid were also shown. In Trial 3, the effects of both these acids, four acid concentrations (0.6, 1.2, 1.8 and 2.4 eq/kg) and three levels of heat treatment required for drying the samples (100, 150 and 200°C for 60, 30 and 20 min, respectively) were evaluated. An interaction acid type × concentration × temperature was shown. In addition, interactions concentration × temperature was shown in each acid. With heat treatments of 100°C to 150°C, benefits were not obtained after increasing the acid dose over 0.8 eq/kg. The increase of the heat treatments to 200°C and the acid dose up to 1.2 eq/kg increased protection, but to exceed this dose did not improve protection. In Trial 4, available lysine, CP solubility in McDougall buffer and IVUCP were compared after treatment with water or solutions (0.8 eq/kg) of orthophosphoric or malic acids using 100°C and 150°C heat treatments as described in Trial 3. No effects on available lysine were observed. Both CP solubility and IVUCP were reduced to a greater degree by acids than by water treatment. The results showed a high effectiveness of acid-heat treatments. Levels of protection are dependent on the acid dose, its dilution, acid type and drying conditions.     

Ruminal degradability and in vitro intestinal digestibility of sunflower meal and in vitro digestibility of olive by-products supplemented with urea or sunflower meal: Comparison between goats and sheep

The in vitro digestibility of two-stage dried olive cake (TSDOC) and olive leaves (OL) unsupplemented or supplemented with increasing amounts of urea (U) or sunflower meal (SM) (0, 1.5, 2 and 2.5 g/100 g organic matter (OM) of the by-product) was determined. Chemical and amino acid composition, in vitro digestibility, in situ rumen degradability of crude protein and amino acids, and in situ–in vitro intestinal digestibility of SM CP and amino acids was determined. The in sacco rumen degradability and in vitro intestinal availability of CP and individual amino acids were also determined. Results obtained in Granadina goats and Segureña wethers were compared. SM provides arginine, glycine and aspartic and glutamic acids. The addition of increasing amounts of U or SM improved (P<0.001) the IVDMD and IVOMD of both TSDOC and OL. There was no effect (P>0.05) of the rumen inoculum origin on in vitro TSDOC digestibility. In contrast, values for OL were higher (P<0.001) for goats versus sheep. In sacco ruminal CP degradability of SM was relatively high, and similar in sheep and goats (ED=0.78 and 0.75 for sheep and goats). Individual amino acid ruminal degradability had different values, being lowest for methionine, leucine, proline, tyrosine and cysteine. Values obtained for individual amino acids differed from those of CP. Apparent intestinal digestibility of undegraded protein (AIDUP) of SM was high (0.86 and 0.98, respectively, for sheep and goats). The intestinally absorbable protein (IADP) was low (18.9 and 24.0 for sheep and goats, respectively). Results indicate that goats and sheep have the same capacity for TSDOC digestion, but goats showed a better capacity than sheep for OL utilisation. Although the amino acids supply to the intestine from SM is not important it could be a good supplement for low degradable protein feedstuffs such as TSDOC and OL.     

Effects of different processing methods of flaxseed on ruminal degradability and in vitro post-ruminal nutrient disappearance

The aim of the study was to determine the effects of different heat-processing methods of flaxseed on the in situ effective dry matter degradability (EDMD) and the in situ effective crude protein degradability (ECPD). The treatments included roasting, steep roasting, rolled roasting, rolled steep roasting, microwave irradiation and extrusion. Three rumen-fistulated sheep were used for in situ incubations. Furthermore, the effects of heat-processing methods on post-ruminal in vitro nutrient disappearance and total tract disappearance were measured by a three-step in vitro technique. The seeds were roasted and extruded at 140°C to 145°C. One lot of roasted seeds was gradually cooled for about 1 h (roasting) and another lot was held in temperature isolated barrels for 45 min (steep roasting). Moreover, roasted and steep roasted flaxseed was rolled in a roller mill. The lowest and highest EDMD was observed for unheated and extruded flaxseed, respectively (p < 0.05). The highest ECPD was observed for extruded flaxseed (p < 0.05). Roasting and microwave irradiation reduced ECPD of flaxseed (p < 0.05). In vitro post-ruminal disappearance of crude nutrients including fibre fractions was highest for rolled-roasted and rolled steep-roasted flaxseed (p < 0.05). The lowest and highest total tract disappearance rates of crude nutrients and fibre fractions were estimated for unheated and extruded flaxseed, respectively (p < 0.05). The post-ruminal disappearance of crude nutrients was also increased by roasting, in which rolling enhanced this effect. In conclusion, all investigated heat treatments had significant effects on in situ and in vitro degradability of nutrients. As well, rolling of roasted flaxseed enhanced the respective effects. Therefore, different methods of heat processing can be used to modify the feed value of flaxseed for specific purposes.     

Effects of ensiling on in situ ruminal degradability and intestinal digestibility of corn forage

The effective degradability of dry matter (DM), crude protein (CP) and amino acids (AA), and the intestinal effective digestibility (IED) of DM and CP of a green forage corn (GC) and its silage (EC) were determined on freeze-dried samples using three rumen and duodenum cannulated wethers. Two rumen incubations with duplicate bags were performed for each feed. Rumen degradation was determined on one series of bags from each incubation. The other series was freeze-dried and used to determine IED using mobile nylon bags. Microbial contamination of rumen incubated residues (determined with ¹⁵N techniques) fitted exponential functions, which showed a greater microbial contribution in EC than in GC in the undegradable DM (18.6% vs. 13.5%) and CP (81.7% vs. 69.4%). Degradability was calculated considering the particle rumen outflow rate (k_p : 0.056/h) of the EC (ED_p) or additionally the rate of comminution and mixing (k_c : 0.130/h) of these particles (ED_cp). Ensiling increased ED_p (9.33%, p < 0.01) or ED_cp (5.30%, p = 0.062) of DM and was associated with losses of nitrogen and with large changes in the AA profile. It is necessary to correct the microbial contamination, because it represents 32.0% (GC) and 42.5% (EC) of the undegraded CP when using k_p and k_c . Ensiling caused higher degradabilities for some AA as well as large differences in the changes due to the rumen fermentation on the AA profile. However, it had only limited effects on the undegraded protein profile. Ensiling also reduced the IED of DM (23.3% vs. 14.6%; p = 0.057). In conclusion, results do not show losses of nutritive value by ensiling corn cut at vitreous grain stage.     

Influence of physical treatment of rape expeller,wheat, maize and maize gluten feed on degradability in the rumen and on the enzymatic in vitro digestibility of non degraded crude protein

The influence of physical treatment‐expansion and flaking‐on crude proteins degradability in the rumen was studied in maize, maize‐gluten feed, rape extracted meal and in the expanded one at 120°C and 150°C, rape cake, wheat and flaked wheat by in sacco method. The enzymatic digestibility of crude protein in the rumen undegraded residues of the above mentioned feeds was determined by an enzymatically in vitro method.

The treatment of feed decreased significantly the original solubility and theoretical degradability of crude proteins, and the amount of undegraded crude proteins was increased. Positive influence on the amount of enzymatically digested crude protein was determined in rape expanded at 120 °C and 150 °C (60, 61 and/or 68%). Flaking of wheat had a similar effect. Enzymatic digestibility at undegraded rests where increased by 8–10% after the heat treatment and it remained almost unchanged in expanded maize‐gluten feed.     

Effects of disodium fumarate on ruminal fermentation and microbial communities in sheep fed on high-forage diets

This study was conducted to investigate effects of disodium fumarate (DF) on fermentation characteristics and microbial populations in the rumen of Hu sheep fed on high-forage diets. Two complementary feeding trials were conducted. In Trial 1, six Hu sheep fitted with ruminal cannulae were randomly allocated to a 2 × 2 cross-over design involving dietary treatments of either 0 or 20 g DF daily. Total DNA was extracted from the fluid- and solid-associated rumen microbes, respectively. Numbers of 16S rDNA gene copies associated with rumen methanogens and bacteria, and 18S rDNA gene copies associated with rumen protozoa and fungi were measured using real-time PCR, and expressed as proportion of total rumen bacteria 16S rDNA. Ruminal pH decreased in the DF group compared with the control (P < 0.05). Total volatile fatty acids increased (P < 0.001), but butyrate decreased (P < 0.01). Addition of DF inhibited the growth of methanogens, protozoa, fungi and Ruminococcus flavefaciens in fluid samples. Both Ruminococcus albus and Butyrivibrio fibrisolvens populations increased (P < 0.001) in particle-associated samples. Trial 2 was conducted to investigate the adaptive response of rumen microbes to DF. Three cannulated sheep were fed on basal diet for 2 weeks and continuously for 4 weeks with supplementation of DF at a level of 20 g/day. Ruminal samples were collected every week to analyze fermentation parameters and microbial populations. No effects of DF were observed on pH, acetate and butyrate (P > 0.05). Populations of methanogens and R. flavefaciens decreased in the fluid samples (P < 0.001), whereas addition of DF stimulated the population of solid-associated Fibrobacter succinogenes. Population of R. albus increased in the 2nd to 4th week in fluid-associated samples and was threefold higher in the 4th week than control week in solid samples. Analysis of denaturing gradient gel electrophoresis fingerprints revealed that there were significant changes in rumen microbiota after adding DF. Ten of 15 clone sequences from cut-out bands appearing in both the 2nd and the 4th week were 94% to 100% similar to Prevotella-like bacteria, and four sequences showed 95% to 98% similarity to Selenomonas dianae. Another 15 sequences were obtained from bands, which appeared in the 4th week only. Thirteen of these 15 sequences showed 95% to 99% similarity to Clostridium sp., and the other two showed 95% and 100% similarity to Ruminococcus sp. In summary, the microorganisms positively responding to DF addition were the cellulolytic bacteria, R. albus, F. succinogenes and B. fibrisolvens as well as proteolytic bacteria, B. fibrisolvens, P. ruminicola and Clostridium sp.     

Localization of the ß-subunit of follicle stimulating hormone in cattle and sheep by in situ hybridization

The locus for the beta-subunit of the follicle stimulating hormone gene (FSHB) has been determined in both cattle and sheep by in situ hybridization of a bovine and an ovine cDNA probe, respectively, to metaphase chromosomes. Our results show that the FSHB locus is on cattle chromosome 15 in the region of bands q24-qter and in sheep on the cytogenetically homologous chromosome 15, also in the region q24-qter. The mapping of the FSHB gene in cattle together with the location of other genes (CAT, HBB and PTH) previously found to be syntenic in cattle and on human chromosome 11p, defines an evolutionarily conserved synteny. The localization of the FSHB gene to a cytogenetically homologous region in cattle and sheep is consistent with the hypothesis of extensively conserved chromosome structure in these two species.     

Comparative mapping of sheep inhibin subunit βb to chromosome 2 in sheep and cattle by fluorescence in situ hybridization

A cosmid clone containing the complete sheep inhibin subunit β_B gene (INHBB) was assigned to sheep and cattle homologous chromosome bands 2q31-q33 by fluorescence in situ hybridization. The assignment of INHBB in sheep excludes another candidate gene as the site of the Fec^B mutation.     

Effect of the rumen ciliates Entodinium caudatum,Epidinium ecaudatum and Eudiplodinium maggii,and combinations thereof,on ruminal fermentation and total tract digestion in sheep

The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hay-concentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 × 2 × 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM + EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52- and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH₄-to-CO₂ ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.     

A simplified management of the in situ evaluation of feedstuffs in ruminants: Application to the study of the digestive availability of protein and amino acids corrected for the ruminal microbial contamination

The ruminal effective degradability (RED) and intestinal effective digestibility (IED) for dry matter, crude protein (CP) and amino acids (AA) were estimated by a simplified in situ method using pooled samples from rumen-incubated residues, which represented the ruminal outflow of undegraded feed. The effect of microbial contamination in the rumen was corrected using ¹⁵N infusion techniques. Studies were carried out for soybean meal (SBM), barley grain (BG) and lucerne hay (LH) in three wethers cannulated in the rumen and the duodenum. Uncorrected values of RED for CP obtained either by mathematical integration or our simplified method were similar in all feeds. Microbial N in the pooled samples of SBM, BG and LH were 2%, 11% and 24% of total N, respectively. However, intestinal incubation eliminated this microbial charge by 100%, 99% and 88%, respectively. With microbial corrections, RED showed an increase, and IED showed a decrease, except for SBM. With this correction, intestinal digested CP was reduced by 2% in SBM, 13% in BG and 34% in LH. Corrected IED of AA was relatively similar in SBM (97–99%). However, large variations were observed in BG (74–93%) and in LH (10–88%). Digestion in the rumen and intestine changed the essential AA pattern. Overall, our results support that AA digestion is affected by the characteristics of their radicals and their contents in plant cell wall proteins. The accurate estimation of feed metabolisable AA or protein requires effective measures that are corrected by ruminal microbial contamination. The proposed in situ method largely simplifies these tasks and allows a more complete and less expensive feed evaluation.     

Nutrient composition and in vitro ruminal fermentation of tropical legume mixtures with contrasting tannin contents

Various combinations of a low-tannin herbaceous legume (Vigna unguiculata) and foliage of tanniniferous shrub legumes (Calliandra calothyrsus, Flemingia macrophylla and Leucaena leucocephala) or a low-tannin shrub legume (Cratylia argentea), all mixed together with a low-quality tropical grass (Brachiaria humidicola), were tested in vitro for differences in the effects on ruminal fermentation. Two experiments with the gas transducer technique were carried out, where each forage mixture was tested either with or without polyethylene glycol in order to be able to identify tannin-related effects (n = 3). In Experiment 1, a stepwise replacement of V. unguiculata by C. calothyrsus (5:0, 4:1, 3:2, 2:3, 1:4, 0:5) at a legume proportion of 1/3 or 2/3 in the mixture was evaluated. Together with two grass-alone and four pure legume treatments this added up to 30 treatments. In Experiment 2, V. unguiculata was gradually replaced by each of the four shrub legumes (3:0, 2:1, 1:2, 0:3) in grass–legume ratios of 2:1, adding up, together with two grass-alone treatments, to 28 treatments. When added alone, V. unguiculata resulted in high fermentative activity as measured by gas production and kinetics as well as low proportion of undegraded crude protein. When V. unguiculata was replaced by the low-tannin C. argentea in Experiment 2, there was no noticeable difference (P>0.05) in fermentative activity. In both experiments, the effect of the substitution of V. unguiculata by tanniniferous shrub legumes resulted in a declining gas production and an increasing proportion of undegraded crude protein (P<0.001). However, the extent of these changes depended on the level of replacement and the shrub legume species (P<0.001). The results of Experiment 2 illustrate that this was the consequence not only of different tannin contents (less adverse effects with L. leucocephala than with C. calothyrsus) but also differences in the chemical properties of the tannins present in these shrub legume species (much less adverse effects with L. leucocephala than with F. macrophylla despite similar tannin contents). Furthermore these results indicate that, once the extent of the effects of a tanniniferous legume is known, one may calculate the maximal level of replacement of a low-tannin legume in a grass diet possible without negative effects on ruminal fermentation. This allows to improve dry season grass-based diets with as few as possible of the expensive and less well growing low-tannin legume.     

Influence of feeding whole sunflower seed and extruded linseed on production of dairy cows, rumen and plasma constituents, and fatty acid composition of milk

Holstein cows were fed total mixed rations (TMR) supplemented with protected palm fat (PPF), whole sunflower seed (WSS) or extruded linseed (ELS) for 100 days. Percentage of dietary crude fat was 5.3, 5.1 and 5.1, respectively. Diet had no (p > 0.05) effect on feed intake, milk yield or milk protein content. Percentage of milk fat and yield of fat--corrected milk were significantly increased when diets were supplemented with WSS and ELS. Feeding PPF resulted in the lowest (p < 0.05) ruminal concentration of volatile fatty acids. No significant dietary effect on plasma characteristics was observed. Concentration of polyunsaturated fatty acids (PUFA) was higher (p < 0.05), and PUFA n-6/n-3 ratio lower (p < 0.05), in the milk fat from cows fed ELS compared to WSS. Supplementation of TMR with oilseeds compared to PPF increased the content of CLA in milk fat (p < 0.005) and decreased its atherogenicity, primarily due to a significant reduction of palmitic acid concentration. Both oilseeds significantly improved the spreadability index of manufactured butter. ELS, but not WSS, increased the susceptibility of milk fat to oxidation (p < 0.05). It can be concluded that feeding of oilseeds to dairy cows improved nutritional quality of milk fat, with supplementation with ELS producing an even more desirable milk fatty acid profile than WSS supplementation.     

Influence of feeding whole sunflower seed and extruded linseed on production of dairy cows,rumen and plasma constituents,and fatty acid composition of milk

Holstein cows were fed total mixed rations (TMR) supplemented with protected palm fat (PPF), whole sunflower seed (WSS) or extruded linseed (ELS) for 100 days. Percentage of dietary crude fat was 5.3, 5.1 and 5.1, respectively. Diet had no (p > 0.05) effect on feed intake, milk yield or milk protein content. Percentage of milk fat and yield of fat – corrected milk were significantly increased when diets were supplemented with WSS and ELS. Feeding PPF resulted in the lowest (p < 0.05) ruminal concentration of volatile fatty acids. No significant dietary effect on plasma characteristics was observed. Concentration of polyunsaturated fatty acids (PUFA) was higher (p < 0.05), and PUFA n-6/n-3 ratio lower (p < 0.05), in the milk fat from cows fed ELS compared to WSS. Supplementation of TMR with oilseeds compared to PPF increased the content of CLA in milk fat (p < 0.005) and decreased its atherogenicity, primarily due to a significant reduction of palmitic acid concentration. Both oilseeds significantly improved the spreadability index of manufactured butter. ELS, but not WSS, increased the susceptibility of milk fat to oxidation (p < 0.05). It can be concluded that feeding of oilseeds to dairy cows improved nutritional quality of milk fat, with supplementation with ELS producing an even more desirable milk fatty acid profile than WSS supplementation.     

Further observations on the nature and characteristics of cross protection against Fasciola hepatica produced in sheep by infection with Cysticercus tenuicollis

Dineen J. K., Kelly J. D. and Campbell N. J. 1978. Further observations on the nature and characteristics of cross protection against Fasciola hepatica produced in sheep by infection with Cysticercus tenuicollis. International Journal for Parasitology8: 173–176. Previous studies showed that sheep infected with Cysticercus tenuicollis were protected against a subsequent infection with Fasciola hepatica given at 12 weeks (Campbell, Kelly. Townsend & Dineen, 1977). The present studies showed that these animals were again protected against re-challenge with F. hepatica at 9 months. Resistance was detected about 10 weeks after re-challenge with metacercariae.Sheep in which the initial C. tenuicollis infections were terminated by anthelmintic at 12 weeks, were resistant to the primary infection with F. hepatica but became fully susceptible to the re-challenge at 9 months.These results suggest that maintenance of resistance depends upon persistence of the C. tenuicollis infections. They also indicate that resistance is maintained by cysts in the peritoneum which is remote from the reactive site (liver).Infection with F. hepatica at 3 weeks after infection with C. tenuicollis prevented cross protection against both the primary infection with F. hepatica and re-challenge at 9 months.     

Relationship between hydroxycinnamic acid content,lignin composition and digestibility of maize silages in sheep

Cell wall-bound hydroxycinnamic acids and the composition of lignin were studied in relation to the digestibility of a collection of 91 maize silages in wethers. Total lignin and guaiacyl content showed the highest correlation coefficients with digestibility. Using the above-mentioned chemical parameters, eight equations were also developed to predict digestibility. The prediction of organic matter digestibility produced a high adjusted R ² value (0.487) using total lignin, guaiacyl, esterified ferulic acid and esterified p-coumaric acid content as predictors. The prediction of in vivo dry matter digestibility produced a higher adjusted R ² value (0.516) using the same variables as predictors. Cell wall digestibility depends on a multiplicity of factors and it is not possible to attribute a causal effect on in vivo digestibility to any single factor. However, total lignin, guaiacyl and p-coumaric acid content emerge as good predictors of digestibility.     

Effect of different types of fibre supplemented with sunflower oil on ruminal fermentation and production of conjugated linoleic acids in vitro

Abstract

An in vitro study was conducted to determine the effect of different types of fibre supplemented with sunflower oil on ruminal fermentation and formation of conjugated linoleic acids (CLA) by mixed ruminal microorganisms. Cell wall components extracted from wheat straw (representing lignified fibre), soybean hulls (representing easily digestible fibre), and purified cellulose were used as substrates. Sunflower oil was supplemented at the same level for all three types of fibre. After 24 h of incubation, ruminal fermentation parameters (including 24 h gas production, pH value, concentration of ammonia nitrogen and volatile fatty acids) and the concentration of long chain fatty acids in the culture fluid were determined. Results showed that the type of fibre influenced ruminal fermentation traits and the biohydrogenation of unsaturated C18 fatty acids in vitro. Composition of LCFA and profile of CLA were altered by the fibre type. Compared to the digestible fibre and purified cellulose, lignified fibre significantly increased the production of cis-9, trans-11 CLA and total CLA (sum of cis-9, trans-11 CLA, trans-10, cis-12 CLA, trans-9, trans-11 CLA, and cis-9, cis-11 CLA) by ruminal microorganisms. It was concluded that ruminal fermentation and production of CLA can be affected by the type of dietary fibre.     

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 expander-treating a barley-based concentrate on ruminal fermentation, bacterial N synthesis, escape of dietary N, and performance of dairy cows

Three primiparous dairy cows in early lactation with cannulas in rumen, duodenum and ileum were used in a 3×3 Latin square design to study effects of expander treatment of a barley-based concentrate. The concentrate was either pelleted at 75–80°C or expander treated at 125–130°C prior to pelleting. The diets consisted of 6.7 kg DM of grass silage and 10 kg DM of (1) 100% pelleted, (2) 50% pelleted and 50% expanded or (3) 100% expanded concentrate. The diets were offered as a mixed ration in four equal meals daily. Ruminal fermentation, bacterial N synthesis, duodenal, ileal and faecal flow of nutrients, and animal performance were monitored. Expander treatment numerically increased ruminal digestion of starch, which explained the observed increase in ruminal VFA concentration and the lowered ruminal pH (P<0.05). The proportion of butyrate in rumen liquid increased, whereas the proportion of propionate decreased in the expanded compared to the pelleted treatment (P<0.05). Expander treatment tended to increase rumen volume and rumen NDF pool size. Ruminal digestion of NDF was numerically lower in the expanded than in the pelleted treatment. No differences in bacterial N synthesis or efficiency of synthesis were observed among treatments. Expander treatment numerically increased the duodenal flow of non-ammonia N (NAN) and amino acid N (AAN), and seemed to increase the flow of non-ammonia non-bacterial N (NANBN) to the duodenum to a similar extent as was indicated by nylon bag studies. Milk production and milk fat and protein content were increased by the expander treatment (P<0.05), indicating that expander treatment increased the supply of nutrients for milk production.     

Influence of exogenous enzymes on nutrient digestibility, extent of ruminal fermentation as well as milk production and composition in dairy cows

This experiment studied effects of a mixture of exogenous enzymes (ZADO^®) from anaerobic bacteria on ruminal fermentation, feed intake, digestibility, as well as milk production and composition in cows fed total mixed rations (TMRs; 0.7 corn silage and 0.3 of a concentrate mixture). Twenty lactating multiparous Brown Swiss cows (500 ± 12.4 kg live weight) were randomly assigned into two experimental groups of 10 immediately after calving and fed a TMR with or without (CTRL) addition of 40 g/cow/d of enzymes for 12 weeks. Addition of enzymes increased (P<0.05) rumen microbial N synthesis. Intake of dry matter (DM) and organic matter (OM) was positively influenced (P<0.05) by supplementation, and digestibility of all nutrients was higher (P<0.05) in the total tract of supplemented cows, although the magnitude of the improvement varied among nutrients, with the highest improvement in aNDFom and ADFom (418–584 and 401–532 g/kg respectively; P<0.05) than the other nutrients. Supplementation of enzymes also increased (P<0.05) rumen ammonia N and total short chain fatty acid (SCFA) concentrations, and individual SCFA proportions were also altered with an increase in acetate (61.0–64.8 mol/100 mol; P=0.05) before feeding, and acetate and propionate increased 3 h post-feeding (60.0–64.0 and 18.3–20.8 mol/100 mol respectively; P<0.05). Milk and milk protein production was higher (12.8–15.7 and 0.45–0.57 kg/d respectively; P<0.05) for cows fed the ZADO^® supplemented diet. This exogenous enzyme product, supplemented daily to the TMR of cows in early lactation, increased milk production due to positive effects on nutrient intake and digestibility, extent of ruminal fermentation and microbial protein synthesis.