Effect of Feeding Glycerin on Ruminal Environment and In Situ Degradability of Feedstuffs in Young Bulls

Abstract

This work studied the effect of feeding glycerin in bulls that were fed high levels of concentrate on the ruminal environment and in situ degradability of feedstuffs. Four ruminally cannulated young bulls were assigned to a 4 × 4 Latin square arrangement of treatments. The diets consisted of 15% barley straw and 85% concentrate in dry matter (DM). There were four different concentrates: without glycerin, and with 20, 40 or 80 g of glycerin per kg of DM. Each diet was offered for 24 days, the ruminal fluid was sampled to evaluate the ruminal metabolism and to determine the ruminal bacterial population by quantitative real-time polymerase chain reaction analysis, and the in situ degradability of six different feedstuffs was measured. The treatment with the highest level of glycerin provided the lower pH (p < 0.001), and the acetic/propionic molar ratio decreased (p < 0.001) as glycerin increased. The incorporation of glycerin in the diet did not affect the DNA copies/µL of the total bacteria, Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus (p > 0.05) in the DNA extract of rumen fluid, but at high levels increased Selenomonas ruminantium (p < 0.01). Very few effects of glycerin incorporation were found for the in situ degradability. In young bulls that were fed high levels of concentrate, glycerin at 20 or 40 g/kg of feed could be included without affecting the ruminal pH and raising the propionic acid, but at 80 g/kg the ruminal pH dropped, despite the increase of Selenomonas ruminantium.

Metabolism, Ketosis Treatment and Milk Production after Using Glycerol in Dairy Cows: A Review

“…The DNA concentration for Selenomonas ruminantium was significantly lower at higher doses of glycerol, which may indicate that, unlike maize, glycerol supplementation results in a reduction in starch and sugar availability [ 29 ]. The inclusion of glycerol in the diet of young bulls did not affect the total bacterial count of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus [ 42 ]. Madrid et al [ 42 ] indicate that the high levels of glycerol (80 g of glycerol per kg of DM) cause a decrease in the ruminal pH ( Table 1 ), despite the increase in Selenomonas ruminantium.…”

“…The inclusion of glycerol in the diet of young bulls did not affect the total bacterial count of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus [ 42 ]. Madrid et al [ 42 ] indicate that the high levels of glycerol (80 g of glycerol per kg of DM) cause a decrease in the ruminal pH ( Table 1 ), despite the increase in Selenomonas ruminantium.…”

“…On the other hand, the sulfur-containing gases produced during propylene glycol fermentation in the rumen may contribute to the toxic effects seen in cattle when high doses are administered for therapeutic purposes [ 39 ]. In young bulls that were fed high levels of concentrate, glycerol at 20 or 40 g/kg of DM could be included without affecting the ruminal pH or raising the propionic acid, but at 80 g/kg, the ruminal pH dropped to 5.74 vs. 6.32 in a glycerol-free diet [ 42 ].…”