Effect of additonal feeding with reygrass silage on fermentation in rumen of grazing dairy cows
1998
Gallo, M. | Sommer, A. | Mlynar, R. | Rajcakova, L. (Research Institute of Animal Production, Nitra (Slovak Republic)) | Knotek, S. (Grassland and Mountain Agriculture Research Institute, Banska Bystrica (Slovak Republic))
Intensively managed pasture herbage is a feed rich in crude protein but with lack of energy. It represents an unbalanced way of nutrition for the grazed dairy cows and it can affect their efficiency and state of health. We studied the effect of additional feeding with ryegrass silage and concentrates on production of volatile fatty acids in rumen. The grazing dairy cows of Pinzgau breed were divided into 3 groups with 6 animals in each of them during the experiment. We found out that the concentration of total volatile fatty acids in rumen content was the highest in the second and the lowest in the fourth grazing cycle in all groups (tab. 2). The molar proportion of acetic acid in rumen content was in all three groups quite balanced during the individual cycles (tab. 3). Content of butyric acid (tab. 4) was the highest at first sampling. The values found in further samples showed decreasing tendency in all groups. The molar proportion of propionic acid (tab. 5) was statistically highly significantly higher in the first two samples compared with the following two ones. Decrease of the amount and finally exclusion of the concentrate from the feeding ration in the third and fourth grazing cycle because of decline in efficiency and increased consumption of the grass stand with high content of crude protein resulted in heavy decrease of molar proportion of the propionic acid and increase of molar proportion of acetic acid. It influenced negatively the energetic yield of VFA and the proportion acetate : propionate
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