Effect of virginiamycin on ruminal fermentation in cattle during adaptation to a high concentrate diet and during an induced acidosis.

Abstract

The objective of Exp. 1 was to compare the effects of virginiamycin (VM; 0, 175, or 250 mg x animal(-1) x d(-1)) and monensin/tylosin (MT; 250/ 90 mg x animal(-1) x d(-1)) on ruminal fermentation products and microbial populations in cattle during adaptation to an all-concentrate diet. Four ruminally cannulated, Holstein steers were used in a 4x4 Williams square design with 21-d periods. Steers were stepped up to an all-concentrate diet fed at 2.5% of BW once daily. Ruminal pH, protozoal counts, and NH3-N and VFA concentrations generally were unaffected by VM or MT. Mean counts of Lactobacillus and Streptococcus bovis were lower (P<.05) for VM-treated compared with control or MT-treated steers. Both VM and MT prevented the increase in Fusobacterium necrophorum counts associated with increasing intake of the high-concentrate diet observed in the control. The objective of Exp. 2 was to compare the effects of VM and MT on ruminal pH, L(+) lactate and VFA concentrations, and F. necrophorum numbers during carbohydrate overload. Six ruminally cannulated Holstein steers were assigned randomly to either the control, VM (175 mg/d), or MT (250 + 90 mg/d) treatments. Acidosis was induced with intraruminal administration of a slurry of ground corn and corn starch. The VM and MT premixes were added directly to the slurry before administration. Carbohydrate challenge induced acute ruminal acidosis (pH was 4.36 and L (+) lactate was 19.4 mM) in controls by 36 h. Compared with the controls, steers receiving VM or MT had higher (P<.05) ruminal pH, and the VM group had a lower (P<.05) L (+) lactate concentration. Fusobacterium necrophorum numbers initially increased in VM- and MT-administered steers. In the control steers, F. necrophorum was undetectable by 36 h. Virginiamycin seemed to control the growth of ruminal lactic acid-producing bacteria and, therefore, has the potential to moderate ruminal fermentation in situations that could lead to rapid production of lactic acid.

Combined use of ionophore and virginiamycin for finishing Nellore steers fed high concentrate diets

“…The lactate accumulation in the rumen may account for increased acidosis incidence in ruminant animals, reducing the efficiency of energy utilization. Coe et al (1999) observed that virginiamycin is more efficient in controlling lactate production than ionophores. These authors also observed that mean counts of Lactobacillus and Streptococcus bovis, the major lactic acid producing bacteria, were lower for steers receiving virginiamycin than for those supplemented with ionophores.…”

Liver abscesses in cattle: A review of incidence in Holsteins and of bacteriology and vaccine approaches to control in feedlot cattle12

“…Therefore, conditions that lead to lactate accumulation, such as acute acidosis, should promote proliferation of F. necrophorum. Because lactate accumulation decreases ruminal pH (< 5.5), fusobacterial growth is inhibited (Coe et al, 1999). Despite this, ruminal acidity remains a predisposing factor because the ruminal wall is more likely to permit entry and colonization by F. necrophorum after acid-damage.…”

Adição de virginiamicina em suplemento mineral e proteinado para bezarras Nelore em pastagem de Brachiaria brizantha cv. Marandu na transição seca-águas

“…O aumento de ácido propiônico reduz a energia desperdiçada com a produção de gás, gerando economia de aminoácidos para construção de proteínas. Menor produção de ácido lático e aumento no PH ruminal foram observados por Coe et al, (1999). Ortolan (2010) observou aumento no PH ruminal, aumento na população de protozoários e aumento na taxa de degradabilidade ruminal.…”