Ruminal effects of excessive dietary sulphur in feedlot cattle

Abstract

Sulphur (S) dietary excess can limit productive performance and increase polioencephalomalacia (PEM) incidence in feedlot cattle (FC). Sulphur excess ingested is transformed to hydrogen sulphide (H2S) by sulfo‐reducing ruminal bacteria (SRB), being high ruminal H2S concentration responsible for aforementioned damages. As the ruminal mechanisms involved in H2S concentrations increase have not been elucidated, this study aimed to evaluate the ruminal environment, and the association between ruminal H2S and dissimilatory SRB (DSRB) concentration in FC experimentally subjected to S dietary excess. Twelve crossbred steers were randomly assigned to one of two dietary S levels (6 animals per treatment): low (LS, 0.19% S) and high (HS, 0.39% S obtained by sodium sulfate inclusion at 0.86%). The study lasted 38 days, and on days 0, 22 and 38, ruminal gas samples were taken to quantify H2S concentration, and ruminal fluid to determine total bacteria, DSRB, protozoa, volatile fatty acid and ammonia nitrogen concentration. For ruminal H2S concentration, S dietary × sampling day interaction was significant (p < 0.001), so that the greater concentration was observed on days 22 and 38 with the HS diet. The remaining ruminal parameters were not affected by dietary S level, and no significant correlation between H2S and DSRB concentrations was observed. The ruminal adaptation that maximizes H2S production in FC consuming S excess does not seem to be associated with biological or biochemical alterations, nor DSRB concentration changes. The microbial diversity and ruminal environment were resilient to the S excess evaluated, suggesting that 0.39% of dietary S achieved by 0.86% sodium sulfate addition, could be used without disturbances on digestion nor health of FC.

Effect of Rhodanese Enzyme Addition on Rumen Fermentation, Cyanide Concentration, and Feed Utilization in Beef Cattle Receiving Various Levels of Fresh Cassava Root

“…Feeding excessive levels of sulfur might result in undesirable consequences such as reduced feed consumption, diarrhea, and muscle spasms, lowering ruminant performance [15]. Furthermore, in ruminants, sulfite, a hazardous intermediate sulfur metabolite, may play a major role in the development of polioencephalomalacia (PEM) lesions [16]. The sulfite ion is a strong nucleophile that can destroy thiamine.…”

“…The sulfite ion is a strong nucleophile that can destroy thiamine. Thiamine deficiency appears to be a plausible risk factor in the etiology of PEM caused by excessive sulfur intake [16]. As a consequence, it is more attractive to feed the innovation of fresh cassava root using biological strategies to minimize HCN.…”

Effect of cyanide-utilizing bacteria and sulfur on feed utilization, microbiomes, and cyanide degradation in cattle supplemented with fresh cassava root

“…Furthermore, rhodanese and mercaptopyruvate sulfurtransferase, two enzymes that promote HCN conversion, can be used to supply HCN as a nitrogen source for microbial production 14 . The rumen environment would benefit from the addition of nitrogen supply with fermentable starch from cassava, which would also improve microbial growth on digestibility 34 .…”

Effects of Guanidinoacetic Acid on Ruminal Fermentation and Greenhouse Gas Production Using Fresh Forage and Silage from Different Maize (Zea mays L.) Genotypes

“…It has been reported that during the degradation process, amino acids containing sulfur (S) groups, including methionine and cysteine, are catabolized by rumen microbes to produce H 2 S [76]. Under this assumption, the high production of H 2 S with the ensiled forage of the Amarillo genotype may be associated with the concentration and degradation of the amino acids that comprise it, especially those amino acids that contain sulfur [77]. Meanwhile, the low H 2 S production with the Montesa silage may be attributable to the addition of GAA, since there was an interaction between the genotype and the addition of GAA, and it has been reported that the use of additives may influence the reduction in H 2 S production in the rumen [78].…”