Progress report for GNE19-220
This project reexamines when gut closure happens in neonatal calves, and will pursue a reevaluation by measuring small intestine IgG receptor expression via qPCR and abomasum pH. This will be done by slaughtering calves at different post natal time points and collecting small intestine and abomasum measurements. Research is in progress so conclusions and impact are unknown.
As intestinal immunoglobulin receptor expression is the determining factor for immunoglobulin absorption and thus TPI, the window for neonatal gut closure needs to be completely re-evaluated and based directly on the expression of the intestinal immunoglobulin receptors. As recent data from our lab indicates that colostrum produced at 16 hours post parturition still contains elevated IgG levels (126 g/L). We also determined based on FcRN gene expression that the mammary gland actively secretes IgG during the post-partum period of lactation. These findings indicate that the currently accepted timing of gut closure (12 hours) could be inaccurate, and current colostrum feeding practices effectively truncate the physiological period of time in which immunoglobulin absorption can occur in the calf intestine. The following objectives will allow us to address this gap in our knowledge, and allow us to apply new information learned to help dairy producers with colostrum management: 1. Precisely and quantitatively determine the full window of time that a neonatal calf intestine can absorb colostrum immunoglobulins. We will use quantitative polymerase chain reaction (qPCR) to directly measure immunoglobulin receptor expression (mRNA) across the full length of the calf intestine (duodenum, jejunum and ileum). Samples will be collected within 0-30 hours after birth, with calves randomly assigned to one of six different sample collection time point groups: 0, 6, 12, 18, 24 and 30 hours after birth. Concurrently, we will examine for abomasal function (onset of pH and protein degrading enzymes) to determine the period of permissive conditions for IgG uptake. 2. We will develop a colostrum feeding protocol founded on calf intestinal physiology for maximum immunoglobulin absorption. Based on serum IgG measurements by quantitative Western blots, we will also redefine the threshold serum IgG levels that correlate with successful TPI, which will reformulate industry standards and targets for colostrum feeding programs.
Purpose is to reduce waste of colostrum, and reduce overuse of antibiotics in calves. This will be economically helpful to dairy farmers, and environmentally beneficial to all.
We are re-examining when gut closure occurs in Holstein dairy calves by slaughtering neonatal calves at different timepoints after birth, collecting small intestine and measuring the expression of the IgG receptor. Compared to indirectly measuring IgG in calf serum, we are directly measuring the small intestine’s capability to take IgG in from colostrum to systemic circulation, thereby providing transfer of passive immunity. The project involves slaughter and intestine samples, RNA extraction and RT-qPCR to measure IgG receptor expression.
We have collected all intestine samples and done RNA extraction, but gene expression analysis (qPCR) is still in progress.
Not yet completed.
Education & Outreach Activities and Participation Summary
I did one 5 min graduate student research presentation at the Cornell Nutrition Conference in October 2020, to share our preliminary findings.
It will hopefully lead to less colostrum waste, more calves being fed colostrum, and reduced antibiotic use on farms. This will be beneficial for farms economically, and for the environment due to decreased risk of antibiotic resistance.
Not significantly- although it is surprising how much colostrum is wasted that could be fed to calves. I am applying to be an associate professor in an animal science/agriculture department.
The research method of directly sampling small intestine, and questioning the dogma, were key to this projects success. While results are preliminary and not yet published, the results indicate gut closure may occur later than previously thought.