FACTORS AFFECTING DEGRADATION OF BARLEY STRAW IN-SACCO AND MICROBIAL ACTIVITY IN THE RUMEN OF COWS FED FIBER-RICH DIETS II - THE LEVEL OF SUPPLEMENTAL FISH-MEAL
Np. Stritzler et al., FACTORS AFFECTING DEGRADATION OF BARLEY STRAW IN-SACCO AND MICROBIAL ACTIVITY IN THE RUMEN OF COWS FED FIBER-RICH DIETS II - THE LEVEL OF SUPPLEMENTAL FISH-MEAL, Animal feed science and technology, 70(1-2), 1998, pp. 11-22
A diet composed of 76.2% untreated barley straw + 23.8% rye grass hay
was given to three nonlactating cows at 90% of ad libitum intake. The
cows were supplemented via cannulae with three different levels of fis
hmeal in order to make the ration up to 8%, 10% and 14% crude protein
on a dry-matter basis. Treatments were arranged in a Latin Square desi
gn. Nylon bags containing untreated barley straw were incubated in the
rumen of the cows for up to 72 h. Degradability of dry matter, total
organic matter and the individual components of the cell wall of barle
y straw were affected by the protein level of the diet. The inclusion
of fishmeal to a level of 14% dietary protein produced the highest deg
radability of all parameters measured. The protein level also affected
ammonia and total VFA concentrations; both fermentation products were
highest in the treatment with the high fishmeal level, Rumen pH and r
umen outflow rate of liquid and particulate phases were not affected b
y protein level, The ATP concentration found in the solid residue, rem
aining after removal of the liquid phase from the rumen content, incre
ased with increasing fishmeal level, while ATP in the liquid phase rem
ained unchanged. This indicates that, under the conditions of this stu
dy, fishmeal exerts its effects on the microbes intimately associated
to the fibre, and not upon the whole microbial population. The microbi
al DNA concentration of digesta within nylon bags increased during the
first 24 h of incubation and then decreased until the end of incubati
on, indicating a process of colonization and depletion of degradable s
ubstrates. (C) 1998 Elsevier Science B.V.