Transient feeding of a concentrate-rich diet increases the severity of subacute ruminal acidosis in dairy cattle1

Abstract

The objective of this study was to investigate the effect of the pattern of concentrate-rich feeding on subacute ruminal acidosis (SARA), its severity, and the corresponding changes in VFA concentration. Eight rumen-cannulated Holstein cows were assigned to a 2 × 2 crossover design with 2 SARA challenge models and 2 experimental runs ( = 8 per treatment). Each run lasted for 40 d, consisting of a 6-d baseline, a 6-d gradual grain adaptation, and a 28-d SARA challenge period. The 2 SARA challenge models were transient (TRA) and persistent (PER) SARA. Initially, all cows were subjected to a forage-only diet (baseline) and gradually switched to 60% concentrate (DM basis). Then, cows in the PER model were continuously challenged for 28 d, whereas cows in the TRA model had a 7-d break from the SARA diet and were fed the forage-only diet after the first 7 d of SARA challenge. Thereafter, the TRA cows were rechallenged with the SARA diet. Wireless ruminal pH sensors were used to obtain ruminal pH profiles and temperature over the experimental period. For the determination of VFA, free ruminal liquid (FRL) and particle-associated ruminal liquid (PARL) were collected once for the baseline and twice (d 20 and 40 for the PER model) or 3 times (d 13, 30, and 40 for the TRA model) during SARA, each time at 0, 4, and 8 h after the morning feeding. Cows in both models experienced SARA albeit with day-to-day variation. From the start until the first 7-d SARA, cows of both models had similar pH profiles, but during the rechallenge, SARA was more severe in the TRA model than in the PER model based on lower daily mean ruminal pH (5.93 vs. 6.15; SEM 0.058) and double the amount of time at pH < 5.8 (497 vs. 278 min; SEM 68.61, < 0.05). Mean ruminal temperature was raised during SARA compared with the baseline (38.9 vs. 38.7°C; SEM 0.057, < 0.001). Concentrations of VFA increased with increasing time after feeding ( < 0.001). In general, SARA challenge (d 40 vs. the baseline), but not the challenge model, altered VFA concentrations and profile of both FRL and PARL by increasing the amounts of propionate and butyrate, whereas total VFA concentration was less affected. Proportions of VFA shifted over the duration of SARA challenge with more propionate but less acetate and butyrate proportions with advancing days of SARA challenge, leading to the values of the last SARA day being different from the earlier days ( < 0.05). In conclusion, the TRA condition led to the higher severity of SARA, but factors beyond feed intake and VFA alterations seemed to play a role.

Factors Affecting Rumen Microbial Protein Synthesis: A Review

“…12 Oxygen concentration: The rumen is a suitable environment for the development of a large number of anaerobic microorganisms, having unique characteristics such as temperature around 38 to 42 °C. 22 But normally, the temperature was more commonly found to be 39 °C. 23,24 Rumen environment is anaerobic, and hence most of the bacteria are obligate anaerobes.…”

Intramammary infusion of Escherichia coli lipopolysaccharide negatively affects feed intake, chewing, and clinical variables, but some effects are stronger in cows experiencing subacute rumen acidosis

“…Cows of the CON group received the same diet throughout the experiment, consisting of a TMR that contained 27% concentrates (DM basis), whereby these cows had additional access to a concentrate mixture for dairy cows at a maximum allowance of 4 kg per cow and day (Table 1), reaching an overall concentrate level of approximately 40% of the total daily DMI. The SARA feeding regimen was an intermittent concentrate-rich feeding challenge, as adapted from Pourazad et al (2016). This feeding challenge consisted of feeding cows a TMR with 60% concentrate (Table 1) for 8 d (SARA 1), switched for 7 d (SARA break) to the same feeding management as the CON cows, and subsequently stepped up to the 60% concentrate-TMR for the last 17 d of the experiment, whereby the first and the second week of this time were denoted as SARA 2 and SARA 3, respectively, and the remaining 3 d were the intramammary LPS challenge.…”

Ruminal microorganism consideration and protein used in the metabolism of the ruminants: A review

“…The rumen is a suitable environment for the development of a large number of anaerobic microorganisms, having unique characteristics such as temperature around 38 to 42°C (Pourazad et al, 2015). But normally, the temperature was more commonly found to be 39°C (Hoover and Miller, 1991;Kim et al, 2014;Yazdi et al, 2015).…”

“…However, the pH can vary due the nature of the diet, but typically found between 5.5 and 7.0 when ruminants are fed with predominantly on forage diet (Aschenbach et al, 2014). According to Pourazad et al (2015), highly fermentable diets are rapidly converted to volatile fatty acid (VFA) in the rumen. The resulting release of protons can constitute a challenge to the ruminal ecosystem and animal health.…”