The use of effluent from grass silage in the diet of finishing pigs. II. Assessment of nutritive value of fresh and stored effluent

Freshly collected effluent was treated with 2 ml formalin per litre and used to replace 150 g/kg of the dry matter of an all-meal control diet of bacon pigs. Diets containing effluent from either unwilted or wilted crops were compared with the control diet which was also given wet by adding water. Liveweight gains of 10 pigs per treatment from 65 to 86 kg on diets containing effluents from unwilted and wilted crops and on the control diet were 753, 715 and 719 ± 16.8 g/day, respectively, and in the same order feed conversion ratios (corrected to dry matter content of the control diet) were 2.94, 3.10 and 3.07 ± 0.075. None of these differences were significant. There were no significant differences in killing-out yield, in hardness of subcutaneous back-fat when measured by a penetrometer or in abnormal odour rating of subcutaneous back-fat.Formalin at levels of 1 and 2 ml/l and formic acid at levels of 1, 2 and 6 ml/l were added as potential preservatives to 1000 ml quantities of freshly collected silage effluent, which was then stored at 23°C. The 2 ml/l level of formalin and 6 ml/l level of formic acid prevented mould growth for 26 and 19 days, respectively.Freshly collected effluent was stored for 3.5, 14, 28, 56, 112 and 240 days after treatment, with formalin at the rate of 3 ml/l, and used in a pig-feeding trial. Pigs were fed either on a control all-meal diet or an equal dry matter intake of 150 g/kg effluent DM and 850 g/kg meal DM.A total of 120 animals were individually penned and fed twice daily on the experimental diets from 33 kg to slaughter at 82 kg liveweight. Overall mean liveweight gains for effluent and control diets were 646 and 656 ± 7.5 g/day, respectively, and the corresponding feed conversion ratios (DM basis) were 2.69 and 2.64 ± 0.030, neither of the differences being significant. Animal performance did not deteriorate with increasing period of effluent storage. No significant differences were found in carcase lean, back-fat thickness nor hardness of back-fat.A digestibility study was carried out on freshly collected effluent from another source. The level of dietary inclusion was equal to that in the previous experiments and the digestibility of dry matter was 0.831 and 0.819, and of nitrogen 0.822 and 0.827 for the control and effluent diets, respectively. A value of 11.4 MJ/kg dry matter was calculated by difference for the digestible energy of this effluent. In a further digestibility trial, digestible energy values of 14.6 and 14.2 MJ/kg dry matter were calculated by difference for effluents stored for 3.5 and 300 days, respectively.     

Effects of linseed lipids fed as rolled seeds, extruded seeds or oil on organic matter and crude protein digestion in cows

Effects of fatty acids of linseed in different forms, on ruminal fermentation and digestibility were studied in dry cows fitted with ruminal and duodenal cannulas. Four diets based on maize silage, lucerne hay and concentrates (65/10/25 dry matter (DM)) were compared in a 4 × 4 Latin square design experiment where the diets were: control diet (C), diet RL supplied 75 g/kg DM rolled linseeds, diet EL supplied 75 g/kg DM extruded linseeds, and diet LO supplied 26 g/kg DM linseed oil and 49 g/kg DM linseed meal. The diets did not differ in total organic matter (OM) and fibre digestibility, in forestomach and intestinal OM digestibility, and in duodenal N flow. Microbial N duodenal flow tended to be lower for RL versus C diet (P<0.1). Extrusion did not reduce ruminal crude protein (CP) degradation in vivo and in situ. Volatile fatty acid concentration and pattern, and protozoa concentration in the rumen, did not vary among diets. Results confirm the absence of a negative effect of a moderate supply of linseed on rumen function, as well as no effect of extrusion on its ruminal CP degradability.     

Fermentation characteristics and feeding value of ensiled poultry litter containing wheat straw,bagasse or sawdust

Poultry excreta substantially increased the crude protein (CP) content and the calcium and phosporus content of the base bedding materials. The crude fibre (CF) content of sawdust (52.3%) was higher than that of wheat straw (38.9%) and bagasse (30.2%). Dry matter digestibility in vitro (IVDMD) of wheat straw, bagasse and sawdust poultry litters (PL) was 65.4, 64.5 and 48.1%, respectively. Green sorghum fodder when ensiled alone or with 20% wheat straw PL, sawdust PL or bagasse PL on fresh basis contained 4.67, 7.80, 10.00 and 7.55% CP, respectively. Nitrogen-free extract (NFE) content of PL silages was lower than that of the control. Apart from wheat straw PL, all silages accumulated considerable amounts of lactic acid. The total volatile fatty acids (TVFA) concentrations were similar for all silages. The addition of PL caused an increase in the proportion of ammonia nitrogen. A feeding trial with crossbred adult male cattle revealed no significant difference in dry matter (DM), CP and ether extract (EE) digestibility of wheat straw and bagasse PL silages. The CF digestibility was similar for all the silages. Sawdust PL silage, however, was significantly lower (P < 0.05) in digestibility of DM, EE and NFE compared to other PL based silages. The DCP and TDN values for the control, wheat straw, bagasse and sawdust PL silages were 2.0, 60.1; 4.3, 45.3; 6.1, 50.3 and 2.9, 41.9 kg/100 kg DM, respectively.     

Effect of fish oil on ruminal biohydrogenation of C18 unsaturated fatty acids in steers fed grass or red clover silages

Red clover and fish oil (FO) are known to alter ruminal lipid biohydrogenation leading to an increase in the polyunsaturated fatty acid (PUFA) and conjugated linoleic acid (CLA) content of ruminant-derived foods, respectively. The potential to exploit these beneficial effects were examined using eight Hereford × Friesian steers fitted with rumen and duodenal cannulae. Treatments consisted of grass silage or red clover silage fed at 90% of ad libitum intake and FO supplementation at 0, 10, 20 or 30 g/kg diet dry matter (DM). The experiment was conducted with two animals per FO level and treatments formed extra-period Latin squares. Flows of fatty acids at the duodenum were assessed using ytterbium acetate and chromium ethylene diamine tetra-acetic acid as indigestible markers. Intakes of DM were higher (P < 0.001) for red clover silage than grass silage (5.98 v. 5.09 kg/day). There was a linear interaction effect (P = 0.004) to FO with a reduction in DM intake in steers fed red clover silage supplemented with 30 g FO/kg diet DM. Apparent ruminal biohydrogenation of C18:2n-6 and C18:3n-3 were lower (P < 0.001) for red clover silage than grass silage (0.83 and 0.79 v. 0.87 and 0.87, respectively), whilst FO increased the extent of biohydrogenation on both diets. Ruminal biohydrogenation of C20:5n-3 and C22:6n-3 was extensive on both silage diets, averaging 0.94 and 0.97, respectively. Inclusion of FO in the diet enhanced the flow of total CLA leaving the rumen with an average across silages of 0.22, 0.31, 0.41 and 0.44 g/day for 0, 10, 20 or 30 g FO/kg, respectively, with a linear interaction effect between the two silages (P = 0.03). FO also showed a dose-dependent increase in the flow of trans-C18:1 intermediates at the duodenum from 4.6 to 15.0 g/day on grass silage and from 9.4 to 22.5 g/day for red clover silage. Concentrations of trans-C18:1 with double bonds from Δ4-16 in duodenal digesta were all elevated in response to FO in both diets, with trans-11 being the predominant isomer. FO inhibited the complete biohydrogenation of dietary PUFA on both diets, whilst red clover increased the flow of C18:2n-6 and C18:3n-3 compared with grass silage. In conclusion, supplementing red clover silage-based diets with FO represents a novel nutritional strategy for enhancing the concentrations of beneficial fatty acids in ruminant milk and meat.     

Silages containing buckwheat and chicory: quality, digestibility and nitrogen utilisation by lactating cows

The suitability of silages containing buckwheat (Fagopyrum esculentum) and chicory (Cichorium intybus) for the nutrition of dairy cows was determined. Buckwheat and chicory were sown in mixture with ryegrass (Lolium multilorum), and a pure ryegrass culture served as a control forage. Swards were harvested 55 d after sowing and were ensiled after wilting, without additives in small round bales. Finally, buckwheat and chicory made up the dietary dry matter (DM) proportions of 0.46 and 0.34, respectively. Concentrates were restricted to 2 kg/d. Diets were fed to 3 x 6 late-lactating cows for 15 d at ad libitum access. During the collection period (days 10-15) amounts of feed intake and faeces, urine and milk were recorded and samples were taken. Ensilability was good for buckwheat and ryegrass swards, but was so less for the chicory sward, which was rich in total ash. The buckwheat silage was rich in acid detergent fibre (445 g/kg DM) and lignin (75.7 g/kg DM) and contained less crude protein (135 g/kg DM) and ether extract (15.8 g/kg DM) than the other silages. Consistent with that, the apparent digestibility of the organic matter and fibre were lowest when feeding this silage. The potassium concentrations in the chicory and ryegrass silages were high (61 g/ kg) and lower in buckwheat (47 g/kg). No significant treatment effects on intake, body weight, milk yield or milk composition as well as plasma beta-hydroxybutyrate and non-esterified fatty acids occurred. Being lowest in nitrogen (N) content, the buckwheat silage resulted in the lowest urine N losses and the most efficient N utilisation for milk protein synthesis, but this at cost of body N retention. The results show that silages containing buckwheat and chicory may be used as components of the forage part of dairy cows' diets even though they were found to have a lower feeding value than ryegrass silage.     

Nutritional value and mercury content of fish silage for growing pigs

The dry matter content of 18 samples of fish silage prepared from fish species or prawn offal varied from 190 to 274 g/kg (mean 239). Chemical composition (mean and range, g/kg dry matter) was: crude protein 686 (487–882); ether extract 100 (53–211); ash 163 (105–319); and total mercury 1.05 mg/kg (0.24–4.05 mg/kg).The nutritional value of fish silage, prepared from Ocean perch and Nannygai, was investigated for grower pigs. Wheat-based diets were formulated in which fish silage partially or completely replaced soya been meal as the protein supplement. The diets were evaluated over the 20 to 45 kg growth phase. Half the pigs were slaughtered at 45 kg live weight; the remainder were fed on the wheat and soya bean meal diet to 80 kg live weight in order to observe the effect of withdrawal of fish silage at 45 kg on subsequent growth performance and mercury content in the lean tissue.The addition of fish silage improved growth rate (P < 0.05) and food conversion ratio (P < 0.01) during the 20 to 45 kg growth phase. No adverse effects on carcass quality were observed. During the 45 to 80 kg growth phase, when all pigs were fed on the wheat and soya bean meal diet, all produced similar performance. Over the 20 to 80 kg growth phase, the beneficial effects of fish silage on growth rate and feed conversion were maintained.Methyl mercury content in the semi-membraneous muscle of pigs fed on fish silage and slaughtered at 45 kg live weight was 0.085 mg/kg on a wet weight basis. This decreased to 0.018 mg/kg in pigs that had the fish silage withdrawn from the diet during the 45 to 80 kg growth phase.     

Chemical composition,digestibility and in situ degradability of dried and ensiled apple pomace and maize silage

The nutritive value of the dried and ensiled apple pomace (DAP and EAP), taken from two processing factories in Urmia city, was compared with maize silage (MS). For EAP, 1 tonnes of AP was mixed with 100 kg of wheat straw and 5 kg of urea (on fresh weight basis). The chemical composition of all feedstuffs was determined by laboratory analysis. Additionally, pH and the concentration of ammonia-N and volatile fatty acids (VFA) were measured in the EAP and MS silages. An in vivo digestibility study was undertaken with three Gezel wether sheep to determine the digestible organic matter content in the dry matter (DOMD) and to estimate the metabolisable energy (ME) content. The dry matter (DM) and protein effective degradabilities (ED) of the feedstuffs were assessed using a nylon bag method. The mean values of the DM, OM, CP, acid detergent fibre (ADF), neutral detergent fibre (NDF), lignin and acid detergent insoluble nitrogen (ADIN) were, respectively, 749 g/kg fresh weight, 929, 64, 405, 473, 10 and 5.6 g/kg DM for DAP, 284 g/kg fresh weight, 925, 72, 460, 567, 20 and 6.5 g/kg DM for EAP and 429 g/kg fresh weight, 936, 260, 463, 44 and 4.4 g/kg DM for MS. No butyric acid was found in EAP and MS, which indicate good preservation for these silages. However, ammonia-N was higher in MS than EAP. The DOMD values were 690, 654 and 580 g/kg DM for DAP, MS and EAP, respectively. The DOMD and ME values for DAP and MS were significantly higher than those of EAP. The dry matter ED of EAP was significantly lower than that of DAP and MS and there was a significant difference among all feedstuffs in the protein ED where MS was the highest and EAP the lowest. The nutritive value of AP was reduced by the addition of wheat straw. However, ensiling apple with straw is a practical method to preserve such high moisture by-product.     

Methane emission,digestive characteristics and faecal archaeol in heifers fed diets based on silage from brown midrib maize as compared to conventional maize

The aim of the present experiment was to compare silage prepared from maize having a brown midrib (BMR) mutation with control (CTR) maize to identify their effects on enteric methane emission, digesta mean retention time (MRT), ruminal fermentation and digestibility. In addition, the utility of archaeol present in faecal samples was validated as a proxy for methane production. Seven German Holstein heifers were fed total mixed rations with a maize-silage proportion (either BMR or CTR) of 920 g/kg dry matter (DM) in a change-over design. Heifers were fed boluses with markers to measure MRT; faeces were collected for 7 days and rumen fluid was collected on the penultimate day. Methane emission was measured in respiration chambers on one day. Data were analysed by t-test and regression analysis. DM intake did not differ between the two diets. The apparent digestibility of DM and most nutrients was unaffected by diet type, but apparent digestibility of neutral and acid detergent-fibre was higher in those heifers fed BMR than in those fed CTR. Comparisons between diets revealed no difference in particle or solute MRT in the gastro-intestinal tract and the reticulorumen. Concentrations of short-chain fatty acid and ammonia in rumen fluid and its pH were not affected by silage type. Independent of the mode of expression [l/d, l/kg DM intake, l/kg digested organic matter], methane emissions were not affected by maize-silage type, but with BMR, there was a trend towards lower methane production per unit of digested neutral detergent fibre than there was with CTR silage. Results of the present study show that feeding heifers BMR silage does not increase methane emissions despite a higher fibre digestibility as compared to CTR silage. Therefore, it is assumed that improvements in animal productivity achieved by feeding BMR silage, as some studies have reported, can be obtained without extra environmental cost per unit of milk or meat. Neither faecal archaeol content [µg/g] nor daily amount excreted [mg/d] is suitable to predict methane production in absolute terms [l per day]. However, faecal archaeol content has a certain potential for predicting the methane yield [l per kg DM intake] of individual animals.     

Effects of dietary supplementation of rumen-protected folic acid on rumen fermentation,degradability and excretion of urinary purine derivatives in growing steers

The present experiment was undertaken to determine the effects of dietary addition of rumen-protected folic acid (RPFA) on ruminal fermentation, nutrient degradability, enzyme activity and the relative quantity of ruminal cellulolytic bacteria in growing beef steers. Eight rumen-cannulated Jinnan beef steers averaging 2.5 years of age and 419 ± 1.9 kg body weight were used in a replicated 4 × 4 Latin square design. The four treatments comprised supplementation levels of 0 (Control), 70, 140 and 210 mg RPFA/kg dietary dry matter (DM). On DM basis, the ration consisted of 50% corn silage, 47% concentrate and 3% soybean oil. The DM intake (averaged 8.5 kg/d) was restricted to 95% of ad libitum intake. The intake of DM, crude protein (CP) and net energy for growth was not affected by treatments. In contrast, increasing RPFA supplementation increased average daily gain and the concentration of total volatile fatty acid and reduced ruminal pH linearly. Furthermore, increasing RPFA supplementation enhanced the acetate to propionate ratio and reduced the ruminal ammonia N content linearly. The ruminal effective degradability of neutral detergent fibre from corn silage and CP from concentrate improved linearly and was highest for the highest supplementation levels. The activities of cellobiase, xylanase, pectinase and α-amylase linearly increased, but carboxymethyl-cellulase and protease were not affected by the addition of RPFA. The relative quantities of Butyrivibrio fibrisolvens, Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes increased linearly. With increasing RPFA supplementation levels, the excretion of urinary purine derivatives was also increased linearly. The present results indicated that the supplementation of RPFA improved ruminal fermentation, nutrient degradability, activities of microbial enzymes and the relative quantity of the ruminal cellulolytic bacteria in a dose-dependent manner. According to the conditions of this experiment, the optimum supplementation level of RPFA was 140 mg/kg DM.     

Effects of folic acid on growth performance,ruminal fermentation,nutrient digestibility and urinary excretion of purine derivatives in post-weaned dairy calves

This study evaluated the effects of folic acid (FA) supplementation on growth performance, ruminal fermentation, nutrient digestibility and urinary purine derivatives (PD) excretion in dairy calves. Forty-eight Chinese Holstein male dairy calves at 60 ± 3.2 d of age and 89 ± 5.9 kg body weight (mean ± standard error) were assigned to one of four groups in a randomised block design. Calves in control group were fed basal diet, calves in low FA, medium FA and high FA groups with 3.6, 7.2 and 10.8 mg FA per kg basal diet, respectively. The dietary corn silage to concentrate ratio was 50:50 (dry matter [DM] basis). DM intake and average daily gain (ADG) quadratically increased, and feed conversion ratio quadratically decreased with increasing FA supplementation. Ruminal pH linearly decreased, whereas total volatile fatty acids quadratically increased. The unchanged acetate-to-propionate ratio was due to the similar change in acetate and propionate concentration. Ammonia N content quadratically decreased. Digestibility of DM, organic matter, crude protein, ether extract, neutral detergent fibre and acid detergent fibre linearly increased. Activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase linearly increased, but α-amylase and protease quadratically increased. Abundance of Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes linearly increased, but Butyrivibrio fibrisolvens and Prevotella ruminicola quadratically increased. Urinary total PD excretion quadratically increased. The results indicated that FA supplementation increased ADG, ruminal fermentation and nutrient digestibility with promoted ruminal microbial growth and enzyme activity, and the optimum dose was 7.2 mg FA per kg basal diet for calves.     

Effect of wilting and the additives,straw, molasses and urea on the fermentation pattern of maize silage

The process of ensiling was studied in fresh maize (15% dry matter (DM)), wilted maize (18 and 24% DM) and maize mixed with 5–20% of wheat straw (18, 25 and 29% DM). Silages with 24% DM were preserved better than those with lower dry matter content. There was a significant change, with time, in pH, titrable acidity, volatile fatty acids, lactic acid, number of lactic acid bacteria, volatile nitrogen and soluble sugars in all the treatments. There was a significant decline in volatile fatty acids (P<0.05) and ammonia (P<0.01) production, and a significant increase in soluble sugar (P<0.01) in silages made after wilting. A significant decline in titrable acidity (P<0.01), volatile fatty acid production (p<0.05) and ammonia nitrogen (P<0.01), and a significant increase in pH (P<0.01) were found in silages of maize mixed with wheat straw. The overall rate of fermentation decreased during the first few days of fermentation in wilted and wheat straw silages, but the final products had characteristics of a good silage. In the second experiment the effect of urea and molasses was studied on wheat straw plus maize (15:85) silage with an initial DM content of 31–34%. Three levels of molasses (0, 3 and 6% of fresh weight) and two levels of urea (0 and 0.5% of fresh weight) were studied. Urea treatment with 3% molasses was found to be the best on the basis of silage characteristics.     

Effects of pressed beet pulp silage inclusion in maize-based rations on performance of high-yielding dairy cows and parameters of rumen fermentation

Beet pulp contains high amounts of pectins that can reduce the risk of rumen disorders compared to using feedstuffs high in starch. The objective was to study the effects of inclusion of ensiled pressed beet pulp in total mixed rations (TMR) for high-yielding dairy cows. Two TMR containing no or about 20% (on dry matter (DM) basis) beet pulp silage were used. The beet pulp silage mainly replaced maize silage and corn cob silage. The TMR were intentionally equal in the concentrations of energy and utilisable crude protein (CP) at the duodenum. TMR were fed to 39 and 40 dairy cows, respectively, for 118 days. The average daily milk yield was about 43 kg/day. No significant differences in milk yield and milk fat or milk protein content were detected. DM intake of cows was significantly reduced by the inclusion of beet pulp silage (23.0 v. 24.5 kg/day). However, a digestibility study, separately conducted with sheep, showed a significantly higher organic matter digestibility and metabolisable energy concentration for the TMR that contained beet pulp silage. In vitro gas production kinetics indicated that the intensity of fermentation was lower in the TMR that contained beet pulp silage. In vitro production of short-chain fatty acids, studied using a Rusitec, did not differ between the TMR. However, the inclusion of beet pulp silage in the ration caused a significant reduction in the efficiency of microbial CP synthesis in vitro. The amino acid profile of microbial protein remained unchanged. It was concluded that beet pulp silage has specific effects on ruminal fermentation that may depress feed intake of cows but improve digestibility. An inclusion of beet pulp silage of up to 20% of DM in rations for high-yielding dairy cows is possible without significant effects on milk yield and milk protein or milk fat.     

Branched-chain volatile fatty acids and folic acid accelerated the growth of Holstein dairy calves by stimulating nutrient digestion and rumen metabolism

The combined addition of branched-chain volatile fatty acids (BCVFAs) and folic acid (FA) could improve growth performance and nutrient utilization by stimulating ruminal microbial growth and enzyme activity. This study was conducted to evaluate the effects of BCVFA and FA addition on growth performance, ruminal fermentation, nutrient digestibility, microbial enzyme activity, microflora and excretion of urinary purine derivatives (PDs) in calves. Thirty-six Chinese Holstein weaned calves (60 ± 5.4 days of age and 107 ± 4.7 kg of BW) were assigned to one of four groups in a randomized block design. Treatments were control (without additives), FA (with 10 mg FA/kg dietary DM), BCVFA (with 5 g BCVFA/kg dietary DM) and the combined addition of FA and BCVFA (10 mg/kg DM of FA and 5 g/kg DM of BCVFA). Supplements were hand-mixed into the top one-third of total mixed ration. Dietary concentrate to maize silage ratio was 50 : 50 on a DM basis. Dietary BCVFA or FA addition did not affect dry matter intake but increased average daily gain (ADG) and feed conversion efficiency. Ruminal pH and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition did not affect acetate proportion but decreased propionate proportion and increased acetate to propionate ratio. Total tract digestibility of DM, organic matter, CP and NDF was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition increased activity of carboxymethyl cellulase and cellobiase, population of total bacteria, fungi, Ruminococcus albus, R. flavefaciens, Fibrobacter succinogenes and Prevotella ruminicola as well as total PD excretion. Ruminal xylanase, pectinase and protease activity and Butyrivibrio fibrisolvens population were increased by BCVFA addition, whereas population of protozoa and methanogens was increased by FA addition. The BCVFA × FA interaction was significant for acetate to propionate ratio, cellobiase activity and total PD excretion, and these variables increased more with FA addition in diet without BCVFA than in diet with BCVFA. The data indicated that supplementation with BCVFA or FA increased ADG, nutrient digestibility, ruminal total VFA concentration and microbial protein synthesis by stimulating ruminal microbial growth and enzyme activity in calves.     

Effect of volatile compounds in grass silage on voluntary intake by growing cattle

Twenty-four low dry matter (DM) silages differing in fermentation quality were harvested at the same time from a crop that consisted mainly of timothy (Phleum pratense), and meadow fescue (Festuca pratensis). The silage samples were analysed by gas chromatography (GC) - mass spectrometry and gas chromatography - flame ionisation detection in order to determine and quantify volatiles present in silage. The voluntary intake of the 24 silages had been measured in a previous feeding trial with growing steers of Norwegian Red. Thirteen esters, five aldehydes, three alcohols, and one sulphide were identified and quantified. A total of 51 variables describing the chemical composition of the silages were included in a partial least-squares regression, and the relationship of silage fermentation quality to voluntary intake was elucidated. The importance of variables describing silage fermentation quality in relation to intake was judged from a best combination procedure, jack-knifing, and empirical correlations of the variables to intake. The GC-analysed compounds were mainly present in poorly fermented silages. However, compared with other explanatory chemical variables none of these compounds was of importance for the voluntary intake as evaluated by partial least-squares regression. A validated variance of 71% in silage DM intake was explained with the selected variables: total acids (TA), total volatile fatty acids (TVFA), lactic acid/total acid ratio and propionic acid. In this study extent (by the variable TA) and type of silage fermentation (by TVFA) influenced intake. Further, it is suggested that by restricting the fermentation in low DM grass silages the potential intake of silage DM is maximised.     

Survival of <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> in Wilted and Additive-Treated Grass Silage

Grass was field-dried to 3 different dry matter (DM) levels (200, 430 and 540 g/kg) and inoculated with 10⁶–10⁷ cfu/g of a Listeria monocytogenes strain sharing a phagovar occasionally involved in food-borne outbreaks of listeriosis. Formic acid (3 ml/kg) or lactic acid bacteria (8·10⁵/g) with cellulolytic enzymes were applied only to forages with low and intermediate DM levels. Forages were ensiled in laboratory silos (1700 ml) and were stored at 25°C for 30 or 90 days. After 90 days of storage, L. monocytogenes could not be detected in any silo, except one with the high dry matter grass without additive. After 30 days of storage, between 10² and 10⁶ cfu L. monocytogenes/g silage were isolated from the untreated silages. Increasing the DM content from 200 to 540 g/kg did not reduce listeria counts possibly because of the lower production of fermentation acids (higher pH). In silages treated with additives, counts of L. monocytogenes were always lower than in silages without additive. In wet silages (DM 200 g/kg) both additives were effective, but in the wilted silages (DM 430 g/kg) only the bacterial additive reduced listeria counts below detection level. Listeria counts were highly correlated to silage pH (r = 0.92), the concentration of lactic acid (r = -0.80) and the pooled amount of undissociated acids (r = -0.83).     

Replacement of grass and maize silages with lucerne silage: effects on performance,milk fatty acid profile and digestibility in Holstein-Friesian dairy cows

In total, 20 multiparous Holstein-Friesian dairy cows received one of four diets in each of four periods of 28-day duration in a Latin square design to test the hypothesis that the inclusion of lucerne in the ration of high-yielding dairy cows would improve animal performance and milk fatty acid (FA) composition. All dietary treatments contained 0.55 : 0.45 forage to concentrates (dry matter (DM) basis), and within the forage component the proportion of lucerne (Medicago sativa), grass (Lolium perenne) and maize silage (Zea mays) was varied (DM basis): control (C)=0.4 : 0.6 grass : maize silage; L20=0.2 : 0.2 : 0.6 lucerne : grass : maize silage; L40=0.4 : 0.6 lucerne : maize silage; and L60=0.6 : 0.4 lucerne : maize silage. Diets were formulated to contain a similar CP and metabolisable protein content, with the reduction of soya bean meal and feed grade urea with increasing content of lucerne. Intake averaged 24.3 kg DM/day and was lowest in cows when fed L60 (P<0.01), but there was no effect of treatment on milk yield, milk fat or protein content, or live weight change, which averaged 40.9 kg/day, 41.0, 30.9 g/kg and 0.16 kg/day, respectively. Milk fat content of 18:2 c9 c12 and 18:3 c9 c12 c15 was increased (P<0.05) with increasing proportion of lucerne in the ration. Milk fat content of total polyunsaturated fatty acids was increased by 0.26 g/100 g in L60 compared with C. Plasma urea and β-hydroxybutyrate concentrations averaged 3.54 and 0.52 mmol/l, respectively, and were highest (P<0.001) in cows when fed L60 and lowest in C, but plasma glucose and total protein was not affected (P>0.05) by dietary treatment. Digestibility of DM, organic matter, CP and fibre decreased (P<0.01) with increasing content of lucerne in the diet, although fibre digestibility was similar in L40 and L60. It is concluded that first cut grass silage can be replaced with first cut lucerne silage without any detrimental effect on performance and an improvement in the milk FA profile, although intake and digestibility was lowest and plasma urea concentrations highest in cows when fed the highest level of inclusion of lucerne.     

Characterization of Alpine highland pastures located at different altitudes: forage evaluation,chemical composition,in vitro digestibility,fatty acid,and terpene contents

A survey was conducted over the summer of 2013 on two alpine pastures (P1 and P5), and three mountain pastures (P2, P3, and P4). The aim was to determine the botanical composition, pastoral value (PV), variation in chemical composition, gross energy, in vitro true digestibility (IVTD), in vitro indigestible neutral detergent fiber, fatty acid (FA), and terpene contents of pastures located at different altitudes. PV is highest in alpine pastures (25.7 and 26.9, for P1 and P5, respectively). Exploitation of pastures is intensive only for P1 and P2. Pastures differ in dry matter (DM), ash, crude protein, lipid, and gross energy content. Lignin content was significantly higher in P3 (125 g/kg DM), while in other pastures the variation in its average content (from 73 to 94 g/kg DM) was limited. All pastures had IVTD higher than 725 g/kg with the exception of P3 (659 g/kg). As far as FA content is concerned, in all pastures the most abundant were α-linolenic acid (from 495 to 583 g/kg of total FA) and linoleic acid (from 150 to 222 g/kg of total FA), while palmitic acid and oleic acid significantly differ among pastures. α-Pinene, β-pinene, and p-cymene were the most abundant terpenoids.     

Relationships between methane emission of Holstein Friesian dairy cows and fatty acids,volatile metabolites and non-volatile metabolites in milk

This study investigated the relationships between methane (CH₄) emission and fatty acids, volatile metabolites (V) and non-volatile metabolites (NV) in milk of dairy cows. Data from an experiment with 32 multiparous dairy cows and four diets were used. All diets had a roughage : concentrate ratio of 80 : 20 based on dry matter (DM). Roughage consisted of either 1000 g/kg DM grass silage (GS), 1000 g/kg DM maize silage (MS), or a mixture of both silages (667 g/kg DM GS and 333 g/kg DM MS; 333 g/kg DM GS and 677 g/kg DM MS). Methane emission was measured in climate respiration chambers and expressed as production (g/day), yield (g/kg dry matter intake; DMI) and intensity (g/kg fat- and protein-corrected milk; FPCM). Milk was sampled during the same days and analysed for fatty acids by gas chromatography, for V by gas chromatography–mass spectrometry, and for NV by nuclear magnetic resonance. Several models were obtained using a stepwise selection of (1) milk fatty acids (MFA), V or NV alone, and (2) the combination of MFA, V and NV, based on the minimum Akaike’s information criterion statistic. Dry matter intake was 16.8±1.23 kg/day, FPCM yield was 25.0±3.14 kg/day, CH₄ production was 406±37.0 g/day, CH₄ yield was 24.1±1.87 g/kg DMI and CH₄ intensity was 16.4±1.91 g/kg FPCM. The observed CH₄ emissions were compared with the CH₄ emissions predicted by the obtained models, based on concordance correlation coefficient (CCC) analysis. The best models with MFA alone predicted CH₄ production, yield and intensity with a CCC of 0.80, 0.71 and 0.69, respectively. The best models combining the three types of metabolites included MFA and NV for CH₄ production and CH₄ yield, whereas for CH₄ intensity MFA, NV and V were all included. These models predicted CH₄ production, yield and intensity better with a higher CCC of 0.92, 0.78 and 0.93, respectively, and with increased accuracy (C_b) and precision (r). The results indicate that MFA alone have moderate to good potential to estimate CH₄ emission, and furthermore that including V (CH₄ intensity only) and NV increases the CH₄ emission prediction potential. This holds particularly for the prediction model for CH₄ intensity.     

Influence of vitamin E supplementation and basal diet on the vitamin E status, performance and tissue fatty acid concentration in lambs

In order to determine the effect of dietary vitamin E level and basal diet on vitamin E status, performance and tissue fatty acid content, five groups of eight Suffolk × Charollais wether lambs with an initial live weight of 28.4 (s.d. 1.6) kg were allocated to one of five concentrate-based diets supplemented with all-rac-α-tocopheryl acetate to contain 30 mg (C-30), 60 mg (C-60), 120 mg (C-120), 250 mg (C-250) or 500 mg (C-500) α-tocopheryl acetate/kg dry matter (DM), for 63 days. Two additional groups of eight lambs entered the study at 31.2 (s.d. 3.3) kg and were fed grass silage and 400 g/day concentrate for 56 days, with the whole diet providing the equivalent of 60 mg (S-60) or 500 mg (S-500) α-tocopheryl acetate/kg DM. Lambs were weighed and blood samples obtained by venipuncture weekly. Dietary vitamin E level did not affect performance (P > 0.05), but lambs fed grass silage grew more slowly (P < 0.001) and had a higher (P < 0.001) feed conversion ratio (kg feed/kg gain) than those fed concentrates. At day 0 plasma α-tocopherol concentrations were 0.8 μg/ml and did not differ between treatments (P > 0.05). Plasma α-tocopherol concentrations then decreased in all lambs except for those fed S-500, which increased, and at slaughter were (μg/ml) 0.07, 0.23, 0.39, 0.76 and 1.57 in C-30, C-60, C-120, C-250 and C-500 and 1.18 and 1.93 in S-60 and S-500, respectively. At slaughter, muscle and liver α-tocopherol concentrations were in the deficiency range for lambs fed C-30, C-60 or C-120, whereas plasma creatine kinase and tissue polyunsaturated fatty acids were unaffected by dietary vitamin E level, but creatine kinase levels were higher (P < 0.05) and glutathione peroxidise levels lower (P < 0.001) in lambs fed grass silage than concentrates alone. Muscle and liver α-tocopherol concentrations were 1.8- and 4.1-fold higher in lambs fed S-60 than C-60, but there was less of a difference between lambs fed S-500 or C-500 with muscle and liver differences of 0.4- and 0.7-fold, respectively. Tissue n-3 polyunsaturated fatty acid concentrations were higher (P < 0.05) and n-6 fatty acids lower in lambs receiving the grass silage compared to concentrate-based diets, but were not affected by dietary vitamin E level. It is concluded that lower plasma and tissue levels of α-tocopherol are present in lambs supplemented with all-rac-α-tocopheryl acetate on a concentrate compared to a mixed diet of silage and concentrates, and that normal growth can be achieved at tissue levels previously considered to represent deficiency.     

The digestibility and nutritive value for dairy heifers of rations containing cellulose fibre

Cellulose residue (cellufiber) from an ammonium base acid sulphite paper process was accepted by dairy heifers to the extent of 40% of the dry matter of an all-roughage ration when mixed with maize (Zea mays) silage at time of feeding. No adverse physiological effects were observed during digestion trials lasting 80 days in which cattle were given successively diets containing 10, 20, 30 or 40% of the ration dry matter as cellufiber. Apparent digestibility of crude protein decreased and digestibility of crude fibre and acid detergent fibre increased as the cellufiber level in the ration increased. Digestibility coefficients of dry matter, nitrogen-free extract and gross energy were unaffected.Uniformity of values for total digestible nutrients, digestible energy and metabolizable energy and, also, of the body weight gains by the test animals indicated only small differences in nutritive value between rations. However, estimated nutritive values of ration components indicated appreciable differences. The TDN of cellufiber was 56% which was approximately equal to that of alfalfa (Medicago sativa) hay and was 82% of the value of maize silage. However, the digestible energy value of cellufiber (1.93 Mcal/kg DM) was only 77% of alfalfa hay and 69% of maize silage. Similarly, its metabolizable energe value of 1.41 Mcal/kg DM was 69% of that of alfalfa hay and 61% of that of maize silage.