Physiological effects of starter-induced ruminal acidosis in calves before, during, and after weaning

Abstract

The objectives were to nutritionally induce or blunt ruminal acidosis in young calves and to compare indicators of rumen and systemic health. Ten bull calves (n = 5/diet) were ruminally cannulated at 3 wk of age and received milk replacer and 1 of 2 calf starter diets that were designed to cause (AC; pelleted, 42.7% starch, 15.1% neutral detergent fiber, 57.8% nonfiber carbohydrates) or blunt (BL; texturized, 35.3% starch, 25.3% neutral detergent fiber, 48.1% nonfiber carbohydrates) ruminal acidosis. Mean birth weight was 38.7 ± 1.3 kg. Body weight and calf starter intake were measured weekly. Rumen contents were sampled at −8, −4, 0, 2, 4, 8, 12, and 24 h relative to starter feeding during wk 6, 8, 10, 12, 14, and 16 of age. Blood was collected from the jugular vein during the same weeks for complete blood cell count, blood pH, and partial pressures of oxygen and carbon dioxide. Rate of starter consumption was assessed during wk 16. Marker systems were used to estimate liquid passage and volatile fatty acid absorption rates. Calves were slaughtered at 17 wk, and rumen tissue was collected and assessed for papillae length, width, and degree of tissue degradation. Mean ruminal pH ± standard error was 5.37 ± 0.24 and 5.63 ± 0.24 for AC and BL calves, respectively. Lowest pH values were observed the week after weaning. Total ruminal volatile fatty acid concentrations were 131.5 and 124.8 ± 2.4 mM in AC and BL calves, respectively, and increased with age and time after feeding. Dry matter intake was lower in AC calves at wk 4 and remained lower through wk 16. Rate of starter consumption was also lower in AC calves at wk 16. Body weight also was also lower for AC calves from wk 5 through 16. Blood hemoglobin and hematocrit were lower in AC calves, but other blood characteristics were not different. Rumen volume increased with age and tended to be greater in BL calves. Passage rate and papillae length and width were not different between diets, but AC calves experienced a greater degree of tissue degradation. Ruminal acidosis symptoms in calves appear similar to those in adult cattle, and the etiology of the disease seems to follow similar mechanisms. It is clear from this study that symptoms can be moderated by diet, but further research is needed to determine whether symptoms can be nutritionally prevented or whether calves that experience ruminal acidosis are more susceptible to the disease as adults.

Preweaning to postweaning rumen papillae structural growth, ruminal fermentation characteristics, and acute-phase proteins in calves

“…However, studies also reported that high-grain diets caused corneum thickness to remain similar to that found with high-forage diets, but corneum layer sloughing increased (Steele et al, 2011. Ruminal lesions were reported in 2 groups of calves fed either a 42.7 or 35.3% starch diet at 17 wk of age; however, lesions were less severe in calves fed the lower starch diet (Gelsinger et al, 2020). The number of cells increased numerically in the current study over time, which may have resulted in an increase in corneum thickness.…”

Analysis of Host Jejunum Transcriptome and Associated Microbial Community Structure Variation in Young Calves with Feed-Induced Acidosis

“…This work was conducted by using our established acidosis-inducing/blunting model in young calves [ 26 ]. Per our previous report, rumen pH was reported in our recently published work [ 27 ].…”

“…Calves included in this study were part of a larger study that was published [ 26 , 27 , 28 ]. Throughout the experiment, all animal protocols (A005848) were approved by the Animal Care and Use Committee at the University of Wisconsin–Madison.…”

“…In our established model of feed-induced acidosis in young calves, the two diets used in the model were designed to induce or blunt ruminal acidosis. We observed significant physiological differences in the calves receiving each diet, e.g., significantly lower ruminal pH ( p < 0.01) and reduced dry-matter intake ( p < 0.04) and body weight ( p < 0.02) [ 26 ]. The host transcriptome profile in rumen epithelial and liver changed significantly in young calves with acidosis induction [ 27 ].…”

Incorporating Silages into Preweaned Dairy Calf Diets

“…Simultaneously, increased rumen motility and digesta passage out of the rumen, in combination with increased time spent ruminating, prevents excessive ruminal pH drop, via increased volatile fatty acid (VFA) passage to the omasum and increased delivery of buffers to the rumen within saliva. A very low pH is commonly reported in calves fed grain based starter feeds ad libitum and there are indications that it may have a negative impact on performance of calves [29]. Beneficial impacts of forage intake on rumen development are further supported by higher expression of some VFA transporters in ruminal epithelium of calves offered forages in addition to grain based starter feed, compared to those fed only concentrates [7], indicating that the development of ruminal epithelium may also be, to some extent, positively affected by forage intake.…”