Ruminal acidosis underscores the importance of a successful diet adaptation strategy in cattle, and with processed grains comprising the majority of carbohydrate-dense feedlot diets, ruminal organic acid production can exceed absorption and foster an inhospitable drop in pH, according to Texas Tech University researchers writing in a recent issue of Translational Animal Science.
Texas Tech researchers Jonathan DeClerck, Nathan Reeves, Mark Miller, Bradley Johnson and Ryan Rathmann and Gary Ducharme with MS Biotec Inc. noted that while "considerable efforts have been made to alter fermentation by tempering ruminal pH," enhancing organic acid absorption could also mitigate acidosis, and one way to do so is the proper development of the rumen microbiota to improve timely absorption of volatile fatty acids.
DeClerck et al. suggested that a cull cow (presumably on a forage-based diet) could be a "formidable model for an acidosis challenge when placed directly on a concentrate diet for realimentation prior to slaughter."
They conducted a study to clarify the effect of Megasphaera elsdenii NCIMB 41125 (Lactipro Advance; MS Biotec Inc.) on animal health and rumen morphometrics in beef cull cows immediately transitioned to a calorically dense finishing diet.
DeClerck et al. randomized 45 cull beef cows into two treatments to compare the effects of oral drenching of no probiotic versus 100 mL of M. elsdenii on the realimentation of cull cows.
The study featured a rapid zero-day step-up of concentrate-naive cull cows to a 90% concentrate diet (1.43 Mcal/kg of net energy for gain), the researchers said, noting that the cows were finished for 35 days and were fitted with a wireless rumination tag that tracked head movements to record eating and chewing activity. Rumen morphometrics were recorded at slaughter on the harvest floor, with each carcass assigned a rumenitis score and a fragment of the cranial sac removed for further papillae analysis, DeClerck et al. said.
An additional 23 thin, non-fed cull cows were harvested at the same abattoir to compare the effects of concentrate realimentation on ruminal morphometrics, the researchers added.
According to DeClerck et al., M. elsdenii culture-drenched cattle registered a 13.3% increase in rumination time (39.27 min. per day, P = 0.03) during the first week of the trial compared to controls. A numerical rumination advantage for M. elsdenii culture-administered cattle was observed during second week of the trial (P = 0.17), the researchers said, with no differences between treatments for weeks 3-5 (P ≥ 0.40).
Subjective rumenitis evaluations approached a tendency (P = 0.12), with non-M. elsdenii culture-drenched concentrate-fed cattle logging twice the score of their day-zero cohorts (2.52 versus 1.17), suggesting considerable lactic insults occurred to the ruminal epithelium in the short 35-day trial, DeClerck et al. reported.
Despite the short feeding duration, the researchers reported that concentrate realimentation prompted a significant improvement in mean papillae area (P < 0.01). Among concentrate-fed treatments, M. elsdenii culture-drenched cattle posted superior absorptive surface area (P = 0.01) and a greater ratio of papillae area of absorptive surface area (P = 0.05), suggesting that M. elsdenii culture is favorably altering the ecology of the rumen and promoting papillae growth perhaps by mitigating lactate-driven pH drops, DeClerck et al. said.
The researchers concluded that M. elsdenii culture application in a zero-day step-up protocol to finishing diets can help mitigate the effects of ruminal acidosis.