Influence of the maize silage to grass silage ratio and feed particle size of rations for ruminants on the community structure of ruminal Firmicutes in vitro

Aims: To investigate the effect of the forage source and feed particle size (FPS) in ruminant rations on the composition of the ruminal Firmicutes community in vitro. Methods and Results: Three diets, varying in maize silage to grass silage ratio and FPS, were incubated in a rumen simulation system. Microbial samples were taken from the liquid fermenter effluents. Microbial community analysis was performed by 16S rRNA‐based techniques. Clostridia‐specific single‐strand conformation polymorphism profiles revealed changes of the community structure in dependence on both factors tested. The coarse grass silage–containing diets seemed to enhance the occurrence of different Roseburia species. As detected by real‐time quantitative PCR, Ruminococcus albus showed a higher abundance with decreasing FPS. A slightly lower proportion of Bacilli was found with increasing grass silage to maize silage ratio by fluorescence in situ hybridization (FISH). In contrast, a slightly higher proportion of bacterial species belonging to the Clostridium‐clusters XIV a and b was detected by FISH with increasing grass silage contents in the diet. Conclusions: The ruminal Firmicutes community is affected by the choice of the forage source and FPS. Significance and Impact of the Study: This study supplies fundamental knowledge about the response of ruminal microbial communities to changing diets. Moreover, the data suggest a standardization of grinding of feeds for in vitro studies to facilitate the comparison of results of different laboratories.     

Effects of silage from maize crops differing in maturity at harvest,grass silage feed value and concentrate feed level on performance of finishing lambs

The effects of (i) medium and high feed value (MFV and HFV) maize silages and (ii) MFV and HFV grass silages, each in combination with a range of concentrate feed levels, on the performance of finishing lambs were evaluated using 280 Suffolk-X lambs (initial live weight 36.1 kg). The MFV and HFV maize silages represented crops with dry matter (DM) concentrations of 185 and 250 g/kg, respectively, at harvest, and had starch and metabolisable energy (ME) concentrations of 33 and 277 g/kg DM and 9.6 and 11.0 MJ/kg, respectively. HFV and MFV grass silages had DM and ME concentrations of 216 and 294 g/kg and 11.0 and 11.5 MJ/kg DM, respectively. A total of 13 treatments were involved. The four silages were offered ad libitum with daily concentrate supplements of 0.2, 0.5 or 0.8 kg per lamb. A final treatment consisted of concentrate offered ad libitum with 0.5 kg of the HFV grass silage daily. Increasing the feed value of grass silage increased (P < 0.001) forage intake, daily carcass and live weight gains, final live weight and carcass weight. Increasing maize silage feed value tended to increase (P = 0.07) daily carcass gain. Increasing concentrate feed level increased total food and ME intakes, and live weight and carcass gains. There was a significant interaction between silage feed value and the response to concentrate feed level. Relative to the HFV grass silage, the positive linear response to increasing concentrate feed level was greater with lambs offered the MFV grass silage for daily live weight gain (P < 0.001), daily carcass gain (P < 0.01) and final carcass weight (P < 0.01). Relative to the HFV maize silage, there was a greater response to increasing concentrate feed level from lambs offered the MFV maize silage in terms of daily carcass gain (P < 0.05) and daily live weight gain (P = 0.06). Forage type had no significant effect on the response to increased concentrate feed level. Relative to the MFV grass silage supplemented with 0.2 kg concentrate, the potential concentrate-sparing effect of the HFV grass silage, and the MFV and HFV maize silages was 0.41, 0.09 and 0.25 kg daily per lamb, respectively. It is concluded that increasing forage feed value increased forage intake and animal performance, and maize silage can replace MFV grass silage in the diet of finishing lambs as performance was equal to or better (depending on maturity of maize at harvest) than that for MFV grass silage.     

Ensiled sugar beets as dietary component and their effect on preference and dry matter intake by goats

This study examines the influence of ensiled sugar beets (Beta vulgaris ssp. vulgaris) on preference and short-time dry matter (DM) intake of goats. Whole sugar beets were ensiled either without any silage additive (sugar beet silage (SBS)) or with a chemical additive (6 l/t) containing 85% formic and propionic acids (treated sugar beet silage (TBS)) and were chopped after ensiling. The influence of different proportions of SBS (0%, 6.25%, 12.5%, 18.75% and 25% of dietary DM) and TBS (0%, 5%, 10%, 15% and 20% of DM) in partial mixed rations on short-time DM intake by goats (adult Saanen type wethers; n = 10) was studied in two separate, independent trials. Preference behaviour was investigated by offering the goats two different experimental diets per day and offer each possible combination of them (n = 10) once throughout the trial. On this basis, the mean DM intake (within 30 min and 3 h) of each experimental diet was determined. Both sugar beet silages showed good fermentation quality with low pH. By using the chemical silage additive, the production of ethanol was reduced and considerable amounts of sugar were preserved. In the short-term preference experiment, increasing concentrations of sugar beet silage in the ration increased DM intake (p < 0.05) in a linear way with a strong preference for those diets containing high amounts of sugar beet silage. Initial DM intake after 30 min was 4–5 fold increased for diets containing the highest beet concentration. It is assumed that the preference was positively influenced by sugar and sweet taste or the associated higher concentration of metabolisable energy.     

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

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

Effect of maize silage to grass silage ratio and feed particle size on ruminal fermentation in vitro

The effect of the forage source on ruminal fermentation in vitro was investigated for fine (F) and coarse (C) milled diets, using a modified Hohenheim gas production test and a semi-continuous rumen simulation technique (Rusitec). It was hypothesised that the replacement of maize silage by grass silage might lead to associative effects and that interactions related to particle size variation could occur. Five diets with a maize silage to grass silage ratio of 100 : 0, 79 : 21, 52 : 48, 24 : 76 and 0 : 100 differed in their content of CP and carbohydrate fractions, as well as digestible crude nutrients, derived from a digestibility trial with wether sheep. For in vitro investigations, the diets were ground to pass a sieve of either 1 mm (F) or 4 mm (C) perforation. Cumulative gas production was recorded during 93 h of incubation and its capacity decreased with increasing proportion of grass silage in the diet. Across all diets, gas production was delayed in C treatments compared with F treatments. Degradation of crude nutrients and detergent fibre fractions was determined in a Rusitec system. Daily amounts of NH3-N and short-chain fatty acids (SCFA) were measured in the effluent. Degradation of organic matter (OM) and fibre fractions, as well as amounts of NH3-N, increased with stepwise replacement of maize silage by grass silage. Degradability of CP was unaffected by diet composition, as well as total SCFA production. In contrast to the results of the gas production test, degradation of OM and CP was higher in C than in F treatments, accompanied by higher amounts of NH3-N and SCFA. Interactions of silage ratio and particle size were rare. It was concluded that the stepwise replacement of maize silage by grass silage might lead to a linear response of most fermentation characteristics in vitro. This linear effect was also supported by total tract digestibility data. However, further investigations with silages of variable quality seem to be necessary.     

Characterization of protein fractions and amino acids in ensiled alfalfa treated with different chemical additives

Formic acid, formaldehyde, tannic acid or mixtures of two were studied on their effects on ensiled alfalfa (Medicago sativa L.) amino acids and N fractions by the Cornell Net Carbohydrate and Protein System (CNCPS). The alfalfa forage was a second cut and was wilted to a mean over-dry dry matter (DM) content of 330 g/kg. All silages were prepared as mini-silos using 100 ml polypropylene centrifuge tubes (50 g) on a small laboratory-scale, with the additives added in 20 ml aliquots/kg herbage fresh weight (FW). After 35 d of ensiling, most of forage true protein was converted to fraction A and all of the added additives reduced fraction A content in the ensiled forages (P<0.05). The content of fraction B₁ in all of the additive-treated silages was higher (P<0.05) than that in control silage. Large proportions of true protein in the tannic acid/formaldehyde- and formic acid/formaldehyde-treated silages were fractions B₂ and B₃, respectively. No difference was observed on fraction C content between the control silage and silages treated with additives except for the formaldehyde or tannic acid-treated silages. Amino acids were well preserved in additive-treated silages compared with the control silage. Concentration of total amino acid was higher in formic acid-treated silages than that in the control and the other additive-treated silages (P<0.05). The pattern of changes in individual amino acid in all of the silages indicated that branched chain amino acids and methionine were relatively well preserved during fermentation but the basic and acidic amino acids were not.     

水产养殖中益生菌研究进展

益生菌在水产养殖中能够净化水质、预防疾病、促进生长且安全、环保、无抗性,是抗生素的理想替代品,具有重要的研究价值和广阔的应用前景。本文主要从益生菌制剂的定义概述、作用机理及特性进行阐述,分析益生菌制剂存在的问题,探讨水产养殖用益生菌制剂的研究方向。     

微生物饲料添加剂的研究进展

综述了微生物饲料添加剂的分类、作用机理、国内应用现状、发展前景及其存在的问题。     

Effects of condensed tannins in wrapped silage bales of sainfoin (Onobrychis viciifolia) on in vivo and in situ digestion in sheep

The objective of this study was to characterize the condensed tannins (CTs) in wrapped silage bales of sainfoin (Onobrychis viciifolia) and examine their potential action on in vivo and in situ digestive characteristics in sheep. Silage was made from sainfoin, cut at two phenological stages. The first phenological stage, at which silage was made, was from the first vegetation cycle at the end of flowering and the second stage silage was made from regrowth, 5 weeks after the first cut, but before flowering. The silages made from the two phenological stages were fed to 12 rumen-fistulated sheep in a crossover design. Of the 12 sheep, six received polyethylene glycol (PEG) to bind with and remove the effects of CT, whereas the other six were dosed with water. Organic matter digestibility, total-tract N digestibility and N (N) balance were measured over 6 days. Kinetic studies were performed on total N, ammonia N (NH3-N) and volatile fatty acids (VFAs) in rumen fluid before and 1.5, 3 and 6 h after feeding. The kinetics of degradation of dry matter and N from Dacron bags suspended in the rumen were also determined. Biological activity of CT (protein-binding capacity) and CT concentration were greater for the silage made from sainfoin at the early flowering stage. Total-tract N digestibility was increased by the addition of PEG (P < 0.001) to the sainfoin silage before flowering (P < 0.001). CTs decreased N excretion in urine (P < 0.05) and increased faecal N excretion (P < 0.001), but had no effect on body N retention, which is beneficial for the animal. Ruminal N degradability was smaller in the presence of active CT (P < 0.001) at both phenological stages; however, soluble N (P = 0.2060) and NH3-N (P = 0.5225) concentrations in rumen fluid remained unchanged. The results of this experiment indicate that CT in the sainfoin retain their ability to affect the nutritive value of preserved forage legumes.     

Temperate forages ensiled with molasses or fresh cheese whey: Effects on conservation quality, effluent losses and ruminal degradation

Effects of ensiling and adding molasses or increasing levels of fresh cheese whey on the conservation and rumen degradability of temperate pasture silages were evaluated. Forage from three paddocks of mixed grass and legume pastures was used to make 45 silages (15 silages per paddock) with 5 treatments, including silage without additives (control), silage with 15 g/kg dehydrated molasses and silage with 20, 50 and 100 g/kg fresh cheese whey. The chemical composition and fermentation quality (i.e., pH, ammonia N, loss of dry matter (DM) and neutral detergent fibre (NDF), effluent production) of the silages were determined. Fresh and ensiled materials were evaluated for in situ rumen degradability. Ensiling reduced DM and NDF rumen degradability (P<0.01). When additives were employed, the reduction of DM degradability of the silages decreased (P≤0.03). Addition of molasses led to the lowest pH (P<0.01) and DM losses (P<0.01), and highest DM degradability (P<0.01). The conservation and DM degradation results of dried molasses silage was superior to those of fresh whey silages. In general, an increase in the level of whey increased DM degradability (P≤0.03), but linearly increased effluent production (P<0.01) and losses (P<0.01).     

Pilot study on the efficacy of paromomycin as a histomonostatic feed additive in turkey poults experimentally infected with Histomonas meleagridis

Paromomycin is an aminoglycoside antibiotic with activity against protozoa. Currently, paromomycin is registered for food producing animal species. In a pilot study we evaluated the efficacy of different doses of paromomycin in the feed against Histomonas meleagridis in experimentally challenged turkey poults. Groups consisting of 30 birds each were given feed with 100, 200 and 400 ppm paromomycin, respectively, starting on day 1 through to day 42. One group of 30 birds was left untreated. On day 21 all birds were infected intracloacally with H. meleagridis. Additionally, 10 birds were kept as a non-infected and non-treated control group. Before the challenge there was no significant difference between untreated and treated groups with regards to feed consumption and feed conversion rate. After the challenge, mortality was 80% in the infected non-treated birds. In the treated groups the mortality rate was 73.3%, 43.3% and 20%, respectively. No histomonal DNA was found in caeca and livers of the surviving birds. In addition, higher doses of paromomycin (200 and 400 ppm) led to reduced counts of Clostridium perfringens in the droppings. In conclusion, a prophylactic application of paromomycin as a feed additive was effective against the challenge with H. meleagridis under experimental conditions.     

In vitro ruminal fermentation characteristics and utilisable CP supply of sainfoin and birdsfoot trefoil silages and their mixtures with other legumes

The extensive protein degradation occurring during ensiling decreases the nutritive value of silages, but this might be counteracted by tannins. Therefore, silages from two legume species containing condensed tannins (CT) – sainfoin (SF) and birdsfoot trefoil (two cultivars: birdsfoot trefoil, cv. Bull (BTB) and birdsfoot trefoil, cv. Polom) – were compared for their in vitro ruminal fermentation characteristics. The effect of combining them with two CT-free legume silages (lucerne (LU) and red clover (RC)) was also determined. The supply of duodenally utilisable CP (uCP) in the forages was emphasised. The legumes were each harvested from three field sites. After 24 h of wilting on the field, the legumes were ensiled in laboratory silos for 86 days. Proximate constituents, silage fermentation characteristics, CT content and CP fractions were determined. Subsequently, silage samples and 1 : 1 mixtures of the CT-containing and CT-free silages were incubated for 24 h in batch cultures using ruminal fluid and buffer (1 : 2, v/v). Each treatment was replicated six times in six runs. The effects on pH, ammonia and volatile fatty acid concentrations, protozoal counts, and total gas and methane production were determined. uCP content was calculated by considering the CP in the silage and the ammonia in the incubation fluid from treatments and blanks. Statistical evaluation compared data from single plants alone and together with that from the mixtures. Among treatments, SF silage contained the least CP and the most CT. The non-protein nitrogen content was lower, favouring neutral detergent soluble and insoluble protein fractions, in the SF and RC silages. Absolute uCP content was lowest in SF and SF mixtures, although the ratio to total CP was the highest. In comparison with LU, the ammonia concentration of the incubation fluid was lower for SF, RC and BTB and for the mixture of SF with LU. The total gas and methane production was similar among the treatments, and the total volatile fatty acid production was decreased with the CT-containing legumes. Protozoal count was increased with the mixtures containing LU and either SF or BTB compared with single LU. In conclusion, compared with the other legumes, SF and RC have similar advantages as they show limited proteolysis during ensiling. In addition, SF supplies more uCP relative to total CP. The CT-containing legumes also differed in their effect on ruminal fermentation and ammonia formation, probably because of their different CT contents. Thus, SF and its mixtures appear promising for improving the protein utilisation of ruminants.     

Influence of fumaric acid on ruminal parameters and organ weights of growing bulls fed with grass or maize silage

The influence of the potential methane reducer, fumaric acid (FA), on ruminal parameters, the rumen wall and organ weights was investigated in a long-term study with growing bulls. In all, 20 bulls were fed with maize or grass silage as roughage, and with concentrate with or without 300 g FA per animal and day during the whole fattening period. After slaughtering, the organs were weighed and blood serum was analysed for glucose, β-hydroxybutyric acid (BHB) and non-esterified fatty acid concentration. The ruminal fluid was analysed for short-chain fatty acids, ammonia-N and the microbial community via single strand conformation polymorphism analysis. The rumen wall was examined histopathologically and results were graded as ‘no visible lesions’, ‘few inflammatory infiltrates’, ‘some inflammatory infiltrates’ or ‘several inflammatory infiltrates’. In addition, the dimensions of the rumen villi were measured. The FA supplementation decreased the serum BHB concentration and the butyric acid concentration in the ruminal fluid. The microbial community in the ruminal fluid was not influenced by FA. An interaction between FA and silage type was observed for the inflammation centres counted in the villous area of rumen papillae. This interaction was also observed in the length and surface of the rumen villi. Rumen villi results show that the influence of FA depends on the roughage used in the diet.     

Invited review: Improving feed efficiency in dairy production: challenges and possibilities

Despite substantial advances in milk production efficiency of dairy cattle over the last 50 years, rising feed costs remain a significant threat to producer profitability. There also is a greater emphasis being placed on reducing the negative impacts of dairy production on the environment; thus means to lower greenhouse gas (GHG) emissions and nutrient losses to the environment associated with cattle production are being sought. Improving feed efficiency among dairy cattle herds offers an opportunity to address both of these issues for the dairy industry. However, the best means to assess feed efficiency and make genetic progress in efficiency-related traits among lactating cows without negatively impacting other economically important traits is not entirely obvious. In this review, multiple measurements of feed efficiency for lactating cows are described, as well as the heritability of the traits and their genetic and phenotypic correlations with other production traits. The measure of feed efficiency, residual feed intake is discussed in detail in terms of the benefits for its selection, how it could be assessed in large commercial populations, as well as biological mechanisms contributing to its variation among cows, as it has become a commonly used method to estimate efficiency in the recent scientific literature.     

肉碱的生理功能及其应用前景

概述了Ｌ－肉碱的生理功能,及其机能性食品、饲料添加剂、药品方面的应用。     

抗菌肽Lactoferricin生物学功能及其应用研究进展

概述了乳铁蛋白活性多肽(lactofericin)所具有的广谱抗菌、抗寄生虫、抗病毒、抗癌、抗氧化等多种生物学活性,讨论了lactnferricin的制备方法,并对lactnferricin作为饲料添加剂的应用前景作了初步探讨。