Effect of supplementary urea, glucose and minerals on the in vitro degradation of low quality feeds

Oosting, S. J.; Verdonk, J. M. H. J.; Spinhoven, G. G. B.

doi:1989.2.4.583

Article

Ruminant Nutrition and Forage Utilization

Asian-Australasian Journal of Animal Sciences 1989;2(4): 583-590.
https://doi.org/10.5713/ajas.1989.583 Published online December 1, 1989.

Effect of supplementary urea, glucose and minerals on the in vitro degradation of low quality feeds

S. J. Oosting, J. M. H. J. Verdonk, G. G. B. Spinhoven

Abstract

Increasing levels of ammonia-N in the rumen fluid used for in vitro incubation were achieved by supplementation of the ration of the donor cows with urea and by addition of urea either with or without glucose to the rumen fluid after collection. The ration of the donor animals consisted of wheat straw (80%) and maize silage (20%). During the second half of the experiment the basal ration was supplemented with a mineral mixture. Wheat straw, Guinea grass and two rice straw varieties were incubated with the various kinds of rumen fluid. Parameters studied were: solubility, apparent organic matter disappearance after 48 hours of incubation (OMD48), rate of organic matter degradation from 0 to 24 hours of incubation (k1) and from 24 to 95 hours (k2). The concentration of ammonia-N in the rumen fluid at which 95% of the maximal OMD48 and k1 were reached (88.2 and 100.0 mg/l) were independent of the feed. With regard to the k2 the required ammonia-N concentration to reach 95% of the maximal k2 differed per feed. Mineral supplementation increased the OMD48 and k1, but not the solubility and k2. Glucose addition in combination with urea had no beneficial effect compared to urea supplementation alone.

Keywords: In Vitro Degradation; Low Quality Feeds; Urea Supplementation; Mineral Supplementation; Glucose Supplementation