The different particle lengths of the grass silages were achieved by using different harvesting techniques (H=forage harvester, K=short-cut loading wagon, L=long-cut loading wagon). The dry matter content of the grass silage was increased from 35 (T35) to 50% (T50) by extending the wilting time in the field. The basic feed ration consisted of 60% grass silage and 40% corn silage and was supplemented with 25 (K25) and 55% (K55) concentrated feed. The investigation with the rumen-fistulated cattle was carried out in the form of an incomplete Latin square over 6 experimental periods of 14 days each. The experiment with dairy cows was carried out in two separate Latin squares (KF 25 and KF 55) with 12 animals over 6 experimental periods of 14 days each.
The average particle length of the grass silage in groups H, K and L was 38, 62 and 148 mm at a low wilting level (T35) and 32, 61 and 141 mm at a high wilting level (T50). On average for both wilting stages, the average particle length of the total ration in groups H, K and L with low concentrate supplementation (K25) was 20, 31 and 69 mm. With high concentrate supplementation (K55) this was 13, 20 and 42 mm.
In T35, significant effects of the harvesting method were found on the digestibility of OM (73.1, 71.3, 66.2) and the energy content (10.3, 10.1, 9.3 MJ ME) of the grass silages. At a high wilting stage (T50), no influences of the harvesting method were found on the digestibility of the OM (71%) and the energy concentration (10.1 MJ NEL). However, in group T50, mold formed during fermentation or storage. The affected feeding areas could not be fed.
In the study with fistulated cattle (Experiment 1), the harvesting method (H, K, L) had no influence on rumen fermentation, the digestibility of the total ration and the nut and nutrient intake. Significantly less grass silage was consumed in groups T50 than in T35. The pH value and the concentrations of volatile fatty acids and NH3 in the rumen juice were not influenced by the T content of the grass silage. Increasing the proportion of concentrated feed (K25 or K55) led to a reduction in basic feed intake from 9.0 to 6.6 kg T and an increase in total feed intake from 12.0 to 14.6 kg T. In K55, compared to K25 a significantly lower digestibility of the XF (67 or 60%), the NDF (63 or
59%) and the ADF (63 and 59% respectively). The daily mean pH value of the rumen juice in K25 was 6.4, significantly higher than group K55, in which a mean value of 6.2 was found. In the 30-day course of the pH value, the largest differences between the concentrate levels were found around 4 - 7 hours after the start of feeding.
In the studies with dairy cows (Experiment 2), the harvesting method or the particle length of the grass silage did not influence the feed and nutrient intake, nutrient supply, milk production and blood parameters of the cows. Increasing the dry matter content of the grass silages (T35 or T50) significantly reduced the grass silage and forage intake. The basic feed intake was 12.5 (T35) and 11.3 kg T (T50).
However, the animals in group T50 consumed more concentrated feed and also corn silage than in group T35. The increase in the proportion of concentrated feed (K25 or K55) led to a reduction in basic feed intake from 14.2 to 9.6 kg T and to an increase in total feed intake from 19.8 to 21.8 kg T. There were no statistically proven results in milk production Differences between the concentrate levels were found (25.7 and 27.9 kg, respectively). The decrease in fat content from 4.77 to 4.24% was at the limit of significance.
No influence of the particle length of the grass silage or harvesting technique on rumen fermentation, digestibility and feed intake was found. The high wilting of the grass silage led to poorer feed preservation and lower forage intake.
Increasing the proportion of concentrated feed led to a decrease in the pH value in the rumen and a reduction in the digestibility of the structural carbohydrates. With a concentrated feed content of 55%, the ration was at the limit in terms of structural carbohydrate and non-structural carbohydrate supply.
