A.H. van Gelder

Effects of forage maize type and maturity stage on in vitro rumen fermentation characteristics

An experiment with forage maize plants representing early and late-ripening types of Dry Down and Stay Green cultivar types was conducted to study the effects of cultivar and maturity stage on in vitro rumen fermentation characteristics and to investigate the validity of the generally supposed qualities of these cultivars. Plants were harvested at an estimated whole plant dry matter (DM) content of 250, 320 or 390 g kg‾1, on 20 August, 16 September and 3 October 2003, respectively. Chemical composition and in vitro rumen fermentation characteristics, using the gas production technique, were determined of samples from entire not ensiled plants, ears and stover and from entire plants after ensiling. The increase in whole plant DM content from 250 to 320 g kg%sup-1; (20 August - 16 September) caused starch content of the whole plants to increase and neutral detergent fibre (NDF) digestibility to decrease, both more than prolonged ripening (to 390 g DM kg-1). DM content at harvest had a statistically significant influence on degree and rate of in vitro rumen fermentation. Calculated in vitro starch degradation after 10 h of incubation in rumen fluid suggested an increased content of rumen escape starch in the older samples. Maize type had only minor effects on fermentation characteristics, which were most pronounced for the ears and the remaining stover. Although the observed differences caused by the Dry Down or Stay Green characteristics were statistically significant in some cases, they were not systematic not for the early nor for the late-ripening types.

Moorella stamsii sp. nov., a new anaerobic thermophilic hydrogenogenic carboxydotroph isolated from digester sludge.

A novel anaerobic, thermophilic, carbon monoxide-utilizing bacterium, strain E3-O(T), was isolated from anaerobic sludge from a municipal solid waste digester. Cells were straight rods, 0.6-1 µm in diameter and 2-3 µm in length and grew as single cells or in pairs. Cells formed round terminal endospores. The temperature range for growth was 50-70 °C, with an optimum at 65 °C. The pH range for growth was 5.7-8.0, with an optimum at 7.5. Strain E3-O(T) had the ability to ferment various sugars, such as fructose, galactose, glucose, mannose, raffinose, ribose, sucrose and xylose, producing mainly H2 and acetate. In addition, the isolate was able to grow with CO as the sole carbon and energy source. CO oxidation was coupled to H2 and CO2 formation. The G+C content of the genomic DNA was 54.6 mol%. Based on 16S rRNA gene sequence analysis, this bacterium is most closely related to Moorella glycerini (97 % sequence identity). Based on the physiological features and phylogenetic analysis, it is proposed that strain E3-O(T) should be classified in the genus Moorella as a representative of a novel species, Moorella stamsii. The type strain of Moorella stamsii is E3-O(T) ( = DSM 26271(T) = CGMCC 1.5181(T)).

Prediction of in situ rumen escape protein from in vitro incubation with protease from Streptomyces griseus

Research was performed to determine in vitro the amount of rumen escape protein in mainly concentrate feedstuffs by incubation with a proteolytic enzyme preparation of Streptomyces griseus, with 24 feed samples with known in situ crude protein degradation characteristics. A close correlation (R 2 = 0.75) was found between the percentage of escape protein, calculated from the in situ and the in vitro methods. However, the percentage escape protein in situ could be estimated with a greater accuracy (R 2 = 0.80) using the undegraded fraction determined in vitro after 24 h incubation. Expressing escape protein as g kg -1 DM instead of a percentage, further improved the correlation with the amount of escape protein in situ (R 2 = 0.95). The amount of escape protein in situ could be estimated with similar accuracy from the undegraded crude protein fraction determined in vitro after 24 h incubation (R 2 = 0.92). Estimation of the amount of escape protein in situ did not improve with pre-incubation of the samples with amylase and carbohydrate degrading enzymes.

Rumen escape protein in concentrate ingredients determined with the nylon bag and enzymatic techniques

Rumen escape protein (REP) was determined for 26 concentrate feed ingredients using the nylon bag technique and in vitro using a proteolytic enzyme preparation of Streptomyces griseus. In vitro, the samples were incubated for 0, 1, 6 and 24 h. The highest correlation was observed between percentage REP (%REP), determined with the nylon bag technique, and the in vitro undegradable fraction after 1 h of incubation (%U1) (R2= 0.77). Longer incubation times weakened the relationship. %REP could be estimated from %U1 according to: %REP = -0.76 (±5.99) + 0.81 (±0.09) × %U1. The 0 h incubation, representing in vitro solubility, had a relationship (R2 = 0.67) with in situ %REP, suggesting that %REP is mainly determined by crude protein (CP) solubility and to a lesser extent by degradation.

Estimating rumen degradability of forages from semi-natural grasslands using nylon bag and gas production techniques

To determine the ruminal digestion of forages from extensively managed semi-natural grasslands, degradation characteristics and kinetics of silages of three different forages in the rumen of lactating dairy cows were estimated in vitro using the gas production technique (GPT), and in situ using the nylon bag technique. Silages originated from intensively managed grassland (IMG), extensively managed species-poor grassland (SPP) and extensively managed species-rich grassland (SPR). Some individual species originating from extensively managed species-poor and species-rich grasslands were used to estimate their degradability with GPT in order to compare the differences among the species occurring on these two types of grassland. All samples were also analysed for in vitro organic matter digestibility. In situ degradability was estimated by nylon bag incubation in the rumen of three dairy cows at two different periods. Rate of organic matter degradation was highest for IMG (4.93 and 4.54% hs), intermediate for SPR (3.50 and 4.11% s) and lowest for SPP (2.62 and 2.72% h-1). The rates of degradation for protein and neutral detergent fibre were highest for IMG. The undegradable fraction was the same for SPP and SPR. Highest cell wall fermentation was observed for IMG and lowest for SPP, but SPP and SPR did not differ statistically in this respect. Cell wall degradability of the individual species from the species-poor and species-rich grasslands were highest for Lolium perenne and Dactylis glomerata and lowest for Lathyrus pratensis and Anthriscus sylvestris . It is concluded that SPR has the highest potential to become a component of the dairy cow ration.

Ercella succinigenes gen. nov., sp. nov., an anaerobic succinate-producing bacterium

A novel anaerobic succinate-producing bacterium, strain ZWB(T), was isolated from sludge collected from a biogas desulfurization bioreactor (Eerbeek, the Netherlands). Cells were non-spore-forming, motile, slightly curved rods (0.4-0.5 µm in diameter and 2-3 µm in length), and stained Gram-negative. The temperature range for growth was 25-40 °C, with an optimum at 37 °C. The pH range for growth was 7.0-9.0, with an optimum at pH 7.5. Strain ZWB(T) was able to ferment glycerol and several carbohydrates mainly to H2, succinate and acetate. Sulfur and fumarate could be used as electron acceptors by strain ZWB(T). The G+C content of the genomic DNA was 37.6 mol%. The most abundant fatty acids were iso-C14 : 0 and iso-C16 : 0 DMA. On the basis of 16S rRNA gene sequence similarity, strain ZWB(T) belongs to the family Ruminococcaceae and it is distantly related to Saccharofermentans acetigenes JCM 14006(T) (92.1%). Based on the physiological features and phylogenetic analysis, strain ZWB(T) represents a novel species of a new genus, for which the name Ercella succinigenes gen. nov., sp. nov. is proposed. The type strain of Ercella succinigenes is ZWB(T) ( = DSM 27333(T) = JCM 19283(T)).

Effects of chop length and ensiling period of forage maize on in vitro rumen fermentation characteristics

The effect of chop length and ensiling period on in vitro rumen fermentation characteristics of forage maize was studied in two experiments. In the first experiment, maize plants of eight cultivars representing different combinations of Dry Down, Stay Green, early ripening, late ripening, starch and cell wall types were chopped at harvest into pieces of 6 or 15 mm and ensiled in small laboratory silos. After 8 weeks, silage samples were taken and freeze-dried (not ground) before in vitro rumen fermentation characteristics were determined using the gas production technique. Chop length appeared not to affect the in vitro fermentation characteristics. In the second experiment, plants of two of these maize cultivars were chopped into 6-mm pieces and ensiled for different periods in small laboratory silos and in large bunker silos as used in practice. After 0, 14, 42 and 180 days of ensiling, chemical composition and in vitro rumen fermentation characteristics were determined using the gas production technique. The in vitro fermentation characteristics were not influenced by the ensiling period up to 180 days. During the first two weeks of the ensiling period sugar content decreased and so did the gas production caused by fermentation of the soluble components.