Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
Assessment of ruminal fluid pH evolution across the weaning period in Holstein calves under field conditions
Kazana, P., Siachos, N., Panousis...
Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
Read
Objective
The aims of this study were twofold: i) to identify ruminal fluid pH (RFpH) evolution patterns in the peri-weaning period, and ii) to assess the association of these patterns with management practices, performance and metabolic parameters in dairy calves.
Materials and methods
A total of 237 Holstein healthy calves from 8 commercial dairy farms were enrolled in the study. For each calf, date of birth, pre-weaning housing system (individual or group), feeding management (access to hay before or after 4th week of age; ample access to water or not), milk replacer (MR) daily feeding plan (low: 6 L) and method of weaning (abrupt or gradual) were available. At -7d, 0d and +7d relative to weaning (0d), calves were clinically examined and bodyweight (BW) was estimated from heart girth measurement. At the same time-points, blood samples [for serum β-hydroxybutyrate (BHB) and urea nitrogen (BUN) determination] and ruminal fluid samples (for on-site RFpH measurement with a portable pH-meter) were collected, 1-2 h post-feeding. Average daily gain (ADG) was calculated for the pre- and the post-weaning week (ADG1 and ADG2). A hierarchical cluster analysis (HCA) was performed to identify clusters based on RFpH evolution. The RFpH at -7d, 0d and +7d were inserted in the HCA as continuous variables. The number of clusters obtained from the agglomeration schedule was then used in a two-step cluster analysis (TSCA) to establish the RFpH patterns. Comparisons among RFpH clusters were performed using chi-square test and ANOVA, for categorical and continuous variables, respectively. Moreover, multivariable univariate regressions were performed to assess the effect of the RFpH cluster membership variable on BW at -7d, ADG1 and ADG2. Repeated measures mixed models were used to assess the effect of RFpH cluster membership on BHB and BUN. ROC curves were performed to investigate possible BHB and BUN thresholds predicting RFpH classification. All analyses were performed with IBM SPSS v.25.
Results
Calves were classified in 5 clusters (CL). CL1 (n=21) had constantly a RFpH 6.0 at +7d. CL3 was characterized by individually housed calves pre-waning (77%) and a medium plan of MR feeding (87%). CL4 (n=46) had a RFpH constantly >6.0, but with fluctuations during the study period; 72% of calves had early access to hay. CL5 (n=90) had a stable RFpH constantly >6.0. CL5 was characterized by individually housed calves pre-weaning (74%) and a high plan of MR feeding (96%). Mean ADG (kg/d) for each cluster for the pre- (ADG1) and post-weaning period (ADG2) were: CL1 (0.52, 0.78), CL2 (0.47, 0.69), CL3 (0.62, 0.53), CL4 (0.87, 0.55) and CL5 (0.79, 0.40), respectively. Cluster membership had a significant effect only on ADG1 (P<0.05). Calves in CL1 and CL2 had a lower mean estimated ADG1 of 0.992 kg (P<0.001) and 0.607 kg (P<0.05) compared to calves in CL5 and CL4. Moreover, CL5 had a lower proportion (13.3%) of calves losing BW from -7d to 0d compared to CL2 (45.0%, P<0.05) and CL3 (30.0%, P<0.05). Calves in CL1 tended to have lower BW at -7d although they were numerically older than all others. BHB and BUN were significantly affected by cluster membership (P<0.05). BUN was also affected by time-point × cluster interaction (P<0.001). BHB ≥436.2 (μM/L) and BUN <7.85 (mg/ dL) at -7d were identified from the ROC curves as significant thresholds for predicting classification of calves in either CL1 and CL2 or in CL4 and CL5.
Conclusions
During the weaning period, different patterns of RFpH exist and several management factors were associated with them. Patterns of rumen pH >6.0 were associated with higher growth rates, higher BHB and lower BUN values, indicating proper rumen function (enhanced volatile fatty acid production and absorption and better nitrogen utilization efficiency).
Keywords: Calves, Weaning, ruminal fluid pH.
Get access to all handy features included in the IVIS website
- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
- Bookmark your favorite articles in My Library for future reading.
- Save future meetings and courses in My Calendar and My e-Learning.
- Ask authors questions and read what others have to say.
Comments (0)
Ask the author
0 comments