[The effect of types of rations on a straw basis on fermentation and volatile fatty acid production in the rumen of lactating cows. 2. Ruminal fermentation and milk yield criteria after use of a high-fiber straw pellet batch as a basic ration component].

Lactating Black-Pied (DSR) cows were used to study, over a period of 100 days, the influence of different basal ration types (experimental group - straw pellets; control group - dried forage + fodder root crops) on fermentation response and daily production rate of volatile fatty acids (VFA) as well as on some criteria of milk yield. Whilst only slight differences were found between the experimental groups in the molar proportions of VFA, the straw pellet-concentrate ration resulted in a lower VFA production as compared to the conventional ration. The control group's VFA production relativated to energy intake, was found to be of the same level (4.1, 4.3 and 3.9 Mol/1 kilo energetic feed equivalents/cattle) after 30, 60 and 100 days of feeding, respectively. The corresponding values in the experimental group declined from 3.3 to 2.3 and 1.9 Mol/1 kilo EF/cattle when feeding a high-fibre straw-pellet batch as basal ration component. The VFA production rates rather diverging between both groups were not found to have a uniform effect on the milk synthesis processes. Both the daily and the first 100-day milk yields did not differ between the groups but within the range of statistical error. Statistically secured positive correlations were found to exist between concentration and production of VFA which, however, depend on the basal ration type and revealed a relatively wide deviation.