Effects of sulfur and monensin concentrations on in vitro dry matter disappearance, hydrogen sulfide production, and volatile fatty acid concentrations in batch culture ruminal fermentations1

Abstract

Effects of monensin (MON) and S on in vitro fermentation and H(2)S production were evaluated in 2 experiments. In Exp. 1, 2 ruminally cannulated steers were adapted (>14 d) to a 75% concentrate diet [steam-flaked corn (SFC)-based], and ruminal fluid was collected approximately 4 h after feeding. Substrate composed (DM basis) of 85.2% SFC, 9% alfalfa hay, 5% cottonseed meal, and 0.8% urea was added with ruminal fluid and buffer to sealed 125-mL serum bottles to allow for gas collection. A Na(2)SO(4) solution was added to yield S equivalent to 0.2, 0.4, and 0.8% of substrate DM, and MON was included at 0, 2, 4, and 6 mg/L of culture volume. Bottle head-space gas was analyzed for H(2)S. No MON (P = 0.29) or MON x S interaction (P = 0.41) effects were detected for H(2)S production. Increasing S linearly increased (P < 0.01) H(2)S production (micromoles/g of fermented DM). The IVDMD (average 70.0%) was not affected by MON (P = 0.93), S (P = 0.18), or the MON x S interaction (P = 0.56). Total VFA concentrations were not affected by MON (P = 0.87), S (P = 0.14), or the MON x S interaction (P = 0.86), but increasing MON linearly decreased (P <or= 0.01) molar proportions of acetate, butyrate, and the acetate:propionate ratio (A:P), and linearly increased (P < 0.01) the proportion of propionate. In Exp. 2, 2 additional ruminally cannulated Jersey steers were adapted (>21 d) to a 75% concentrate diet (SFC base) that contained 15% (DM basis) wet corn distillers grains plus solubles (WDGS) and MON at 22 mg/kg of DM. In vitro substrate DM was composed of 75.4% SFC, 15% WDGS, 9% alfalfa hay, and 0.6% urea, and S and MON concentrations were the same as in Exp. 1. No effects of MON (P = 0.93) or the MON x S interaction (P = 0.99) were noted for H(2)S production; however, increasing S linearly increased (P < 0.01) H(2)S production. No effects of MON (P = 0.16), S (P = 0.43), or the MON x S interaction (P = 0.10) were noted for IVDMD (average 70.9%). Total VFA concentrations were not affected by MON (P = 0.40), S (P = 0.26), or the MON x S interaction (P = 0.59). As in Exp. 1, increasing MON linearly decreased (P < 0.05) molar proportions of acetate, butyrate, and A:P and linearly increased (P < 0.01) propionate. Increasing S concentration increased in vitro H(2)S production, but S did not affect VFA concentrations and proportions. Monensin did not affect in vitro H(2)S production, and changes in VFA molar proportions were evident with MON regardless of S concentration.

In vitro digestibility and nutritional characterization of distillers dried grains with solubles according to the Cornell Net Carbohydrate and Protein System

“…The IVD of the nutrients was determined in triplicate, using the one-stage technique described by Silva and Queiroz (2002) and adapted to a 24-h fermentation stage as described by Smith et al (2010). Sheep ruminal fluid was collected by vacuum suction pump in the morning, 2 h after the morning feed in order to obtain a suitable microbial population and a minimum number of food particles.…”

“…Every 2 h, the tubes were gently shaken manually to aid the release of formed gases. Three tubes containing only incubation solution were incubated in each run to serve as controls, and three tubes containing only Tifton 85 hay (Cynodon) as index forage (SMITH et al, 2010).…”

Effect of calcium propionate and monensin on in vitro digestibility and gas production

“…The effect of monensin is a function of the dosage. Two in vitro experiments reported that monensin decreased gas production and that the doses were higher than those used in animal feeds (Smith, 2010;Kim et al, 2014a). In contrast, Singh and Mohani (1999) did not find any effect on in vitro gas production using 50 or 100 mg/d of monensin in rumen fluid donors.…”

In vitro and in vivo nutrient digestibility in sheep of rations with and without residue from the extraction of tamarind pulp

“…In each battery, three tubes were placed in an experimental ration containing 0% or 15% RETP which was then incubated with two types of inoculum (sheep ruminal fluid and feces). The samples then underwent 24 h of in vitro fermentation, as adapted from the technique of Smith et al (2010). The IVD of nutrients assay was conducted after the test in vivo digestion.…”