Browsing by Subject "Crude protein"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    Degradation of crude protein and starch of corn and wheat grains in the rumen
    (2016) Seifried, Natascha; Rodehutscord, Markus
    The major objectives of the present thesis were to characterize the ruminal crude protein (CP) and starch degradation of different genotypes of corn and wheat grains and to predict the effective degradation (ED) of CP and starch with easily measurable characteristics. The in situ method is the standard technique to study the ruminal degradation of feeds in many feed evaluation systems. This technique was originally applied to study forages and it was therefore necessary to clarify methodical details related to the measurements of in situ starch degradation from cereal grains. Two in vitro and one in situ approach were conducted to study the loss of secondary starch particles from bags with different pore sizes used for the in situ incubation of different cereal grains. In the first in vitro study ground wheat was incubated in bags (pore size: 50 µm) over different time spans in a modified rumen simulation technique. Bag residues and fermenter fluids were analyzed for their starch content. In the second in vitro study ground wheat, barley, and corn were incubated with bags of pore sizes of 50, 30 (except corn), 20, and 6 µm. In the in situ study ground wheat, barley, corn, and oats were rumen incubated over different time spans using bags with pore sizes of 50, 20, and 6 µm. The starch content of the grains and bag residues was analyzed enzymatically and the degradation characteristics of starch were calculated for each grain type and pore size. It was shown for the first time that incubating wheat and barley in bags with 50 and 30 µm pore size lead to a substantial amount of secondary starch particle losses during incubation process in vitro. These losses were not detectable when the grains were incubated with bags having pore sizes of 20 and 6 µm. Independent of the bags’ pore size no secondary starch particle losses were found by the incubation of corn. Thus corn can be studied in situ even with bags with 50 µm pore size. Oats showed very high washout losses with all pore sizes tested in the present thesis and therefore none of them is suitable to study the starch degradation measurements of oats. Because of methodical problems of gas accumulation in bags having pore sizes < 50 µm, no recommendations can be provided for the in situ evaluation of wheat and barley. Further research is necessary to solve these problems. In the second and third study of the present thesis ruminal in situ degradation of 20 corn grain genotypes and 20 wheat grain genotypes was measured in three lactating Jersey cows. In both experiments the same techniques were used to characterize the ruminal degradation of CP and starch. Ground grains (2 mm) were rumen incubated in bags (50 µm pore size) over different time spans. Grains and bag residues were analyzed for their CP and starch content. The degradation parameters and the ED were calculated for dry matter (DM), CP, and starch. Gas production (GP) of ground grains (1 mm) was recorded after incubation over different time spans in buffered ruminal fluid and fitted to an exponential equation to determine GP parameters. To predict ED of CP and starch correlations with physical and chemical characteristics and in vitro measurements were evaluated and stepwise multiple linear regression analyses were applied. The in situ parameters (soluble fraction, potential degradable fraction, and degradation rate) varied widely between genotypes of corn and wheat grains. The ED of DM, CP, and starch showed a high variation for corn grain genotypes. Due to the high degradation rates, the ED of wheat grains were similar between genotypes. The GP rate was in good agreement with the in situ values for corn grains, whereas no systematic relationship between both methods was observed for wheat grains. Evaluation of correlation analysis showed significant relationships between calculated ED of CP and several amino acids (AA) for both grain types. This indicates that the protein composition of the grains influences CP degradation in the rumen. Similar relationships were found between the same AA and ED of starch of corn grains which highlights the impact of the protein composition on ruminal starch degradation for this grain type. For both grain types, the ED of starch and CP could be predicted accurately from physical and chemical characteristics alone or in combination with GP measurements. Thus, the equations presented in the present thesis can be used to obtain rapid and cost effective information on ruminal degradation of CP and starch for corn and wheat grains. The results of the present thesis show that there is considerable variation of ruminal CP and starch degradation from different genotypes of corn and also – albeit to a lesser extent – for wheat grains. Differences in ED of starch should be taken into account when formulating rations containing significant amounts of corn and wheat grains. In the case of corn grains differences in ED of CP should also be accounted for.
  • Thumbnail Image
    Publication
    Effects of ensiling conditions on the nutritional quality of forage legumes and their impacts on rumen fermentation and nutrient utilization by cattle
    (2022) Aloba, Temitope Alex; Uta, Dickhöfer
    Silage produced from forage legumes can contribute to the limiting protein supply of ruminants diets in the tropics, and reduced dependence on imported and high-carbon footprint feeds. However, the successes recorded with temperate forage legume silage feeding in ruminants have not been achieved in the tropics. Thus, the effects of silage feeding on ruminants’ performance cannot be isolated from the processes that occur during ensiling. Since controllable and uncontrollable factors govern silage quality, it is imperative to understand the processes that occur during ensiling tropical forage legumes under different conditions to widen knowledge. Therefore, the aim was to determine the effect of ensiling conditions on forage legume nutritional quality, their ruminal and post-ruminal fate, and their potential impact on nutrient utilization by cattle in the tropics. A silage study was conducted to evaluate the effects of ensiling length and storage temperature on the nutritive value and fibre-bound protein of three tropical forage legumes ensiled alone or combined with sorghum. The three forage legumes included soybean (Glycine max), lablab (Lablab purpureus) and jack bean (Cannavalia ensiformis). Silages from each legume were made individually or combined with sorghum (Sorghum bicolor) and stored outdoors or indoors for 30, 75, and 180 days. The results showed that the proportion of soluble nutrients preserved in most silage until 75 d of ensiling declined considerably, thereby increasing dry matter (DM) and crude protein (CP) losses, fibre concentration and reducing digestibility afterwards. Besides, storage temperature affected the fermentation and fibre-bound protein characteristics with higher variation in legume silages’ fibre-bound protein than the sorghum-legume silages. Silages of sorghum and soybean were selected from the first study to compose low and high CP diets with additional ingredients, and the effects of ensiling length, storage temperature, and its interaction with CP levels on in vitro rumen fermentation and post-ruminal digestibility were assessed. Dietary treatments were incubated in duplicate for 8 and 24 h in three runs using the ANKOM RF technique to study rumen fermentation. Post-ruminal digestibility was determined using the pepsin and pancreatic solubility procedure. The results showed that gas production (GP) and ammonia-nitrogen in the rumen inoculum increased quadratically with the ensiling length, with the highest GP and ammonia-nitrogen at 75 d of ensiling, irrespective of incubation times. The GP was higher in diets with low than high CP concentrations, while it was the opposite for ammonia-nitrogen. An interaction between ensiling length and storage temperature effect was found for the apparent CP intestinal digestibility. Overall, ensiling beyond 75 d reduces CP digestibility to the extent that it cannot be recovered by supplying additional CP. In the third study, the effects of CP levels on nutrient intake, digestibility, nitrogen metabolism and performance of growing steers fed corn or corn-soybean silage were investigated. Sixteen growing steers were fed with rations based on corn or corn-soybean silage at high or low CP levels in a 4 × 3 incomplete Latin square design comprising 17 d periods, each with 12 d of adaptation to dietary treatments and 5 d of sampling. While the effect of silages and CP levels were not found for nutrient intake, the apparent total tract digestibility of nutrients was reduced for low than high CP in both silages, with greater differences between the CP levels in corn than corn-soybean silage. The average daily gain and feed efficiency were greater in low than high CP of corn silage, but no differences between CP levels were found in corn-soybean silage. In general, corn silage with low CP concentration but with a high metabolizable energy supply supposedly improved nitrogen use efficiency with a higher yield of microbial protein and average daily gain than other diets. Conclusively, the results of the current thesis showed that ensiling forage legumes individually or in combination with cereal crops beyond 75 d at high temperatures of the tropics leads to a decline in the nutritional quality of legume silage and CP intestinal digestibility even with additional CP sources. Furthermore, prolonged ensiling of combined legume and cereal crops reduces nutrient availability for cattle performance.
  • Thumbnail Image
    Publication
    Effects of stand density and N fertilization on the performance of maize (Zea mays L.) intercropped with climbing beans (Phaseolus vulgaris L.)
    (2022) Villwock, Daniel; Kurz, Sabine; Hartung, Jens; Müller-Lindenlauf, Maria
    Maize is Germany’s most important fodder and energy crop. However, pure maize cultivation has ecological disadvantages. Moreover, its yield is low in crude protein, an important feed quality parameter. Maize–bean intercropping can potentially address both issues. A bean variety specially developed for intercropping was first introduced in 2016. Using this variety, a network of institutions conducted 13 field trials from 2017 to 2020 on four sites in Germany. We sought to determine the effects of stand density and nitrogen (N) fertilization on dry matter yield, crude protein yield, and soil mineral N content (Nmin) at harvest of intercropped vs. pure maize. The three intercropping bean densities we tested (7.5, 5.5, and 4 plants/m2) produced non-significantly different yields of dry matter or crude protein, given a maize density of 7.5–8 plants/m2. Intercropping was inferior to pure maize in dry matter yield, but non-significantly different in crude protein yield. Under neither cropping strategy were significant losses in dry matter or crude protein yield recorded with reduced compared to full N fertilization. At full fertilization, however, both pure maize systems and the 8/4 maize–bean intercrop system left significantly higher Nmin at harvest than the other variants of the corresponding system or N fertilization level and thus an increased risk of nitrate leaching. We encourage further optimization of yield performance in maize–bean intercropping, e.g., through breeding or promotion of biological N fixation via rhizobia inoculation. Furthermore, we recommend reducing N fertilization levels in maize cultivation.