This experiment was to test the levels of pain in dairy cows when they are given an intramammary infusion as well as a randomly allocated quarters with lipopolysaccharides, lipoteichoic acid or a control. The cows were given a week to acclimate to the facility and their stalls. In total there were 16 cows used, (12 holstein and 4 swiss fleckvieh) the cows were randomly put into 3 groups for testing.
The cows were monitored 24 hours before and 26 hours after treatment, and were examined to make sure they were at suitable health level.. Their heart rate, breathing, and rectal temperature were monitored on an hourly basis except heart rate, which was continuously monitored. The cows were also milked twice. The day before the challenge baseline (control) parameters were recorded for an 8 hour period. The behavior, and eating habits were monitored and their hock-to-hock distance was measured, during the 8 hour period on the day before and the challenge day.
When after the infusions biopsies were taken, one from the liver and 2 from the udder. For the pain response, the results were measured and organized into 2 categories one being symptoms and the other one being divided into subcategories that used a number system to measure the response, except for one category which was measuring the cows posture. The numbers used ver on a VAS scale with 100 mm being the worst pain. For the utters, they measured the edema and the udder palpitation, separately but using the same scoring system. The temperature of the udder was also taken. There was a pressure put on the udders until a behavioral response was recorded. The pressure was at a constant rate of 5 N/s maxing out at 24.6 N, with two measurements per quarter taken every 60 seconds. Then the results were averaged. During the challenge day there were samples of cortisol concentrated in the milk and plasma taken. The samples were stored at -20 celcius and tested every 2 hours. Somatic cells in the fresh milk were measured every 2 hours. At the end of the experiment the cows were examined and given a clinical pain assessment by people bind to the study.
All measurements recorded are referenced by the day time and treatment each cow was given. The demographics of the cows were ranked in correlation coefficients between the total pain index and with VAS and the index with SCC and were calculated using a software called sigmaplot 12.0 There were a total of 16 challenges done, with no more than 2 being conducted at a time. Of the 16 one was excluded, due to the fact that it did not respond to the challenge with the expected increase. All but one cow recovered from the trial, and the one that did not had to be given rescue analgesia. The heart rate, respiratory rate, and rectal temperatures stayed similar between the cows with no real significant variations. On the behavioral side, each cow ayed down less on the challenge day than they had on the day previous. Eating wise the lipopolysaccharide group at less than they had the day previous. The Hock-to-hock distance remained constant throughout without any differences among the groups. On challenge day the pain idec was higher for all three groups, with the LPS group having higher numbers than the control. On the day of challenge the VAS for the LTA group were found to be higher at hours 3,4, and 5 compared to the LPS group. For the control group the VAS was higher after the 5th hour. For the udder palpitations there were mild responses on the challenge day compared to the control.
As for the udder edema there was a higher recording as time went on during the challenge day, for both the LPS and the LTA groups in comparison to the control. Udder temperature for both test groups were higher after 6 to 8 hours and were both very similar in results. There was not significant change in the plasma cortisol. however for the milk cortisol the LPS group’s results levels were higher after 4 hours and the LTA group’s results were lower after 2 hours. No changes over time were recorded for the control.
This study was designed to evaluate and compare what effects an intramammary challenge using LTA and LPS would have on a cow, and the level of pain it would cause.
The results showed that the LPS had a greater effect on the pain levels experienced by the cows. This leads us to the conclusion that the hypothesis must be rejected based on the data collected. In this study there were a few things that i would have changed. The number of cows used is not large sample size, and would not accurately represent the population at large. So an increased sample size is needed for more accurate results.
I also would have stuck to one species of cow. For the control they used the same cows just one day before, I would have liked to see them have a control where they were injected with something benign and had a “placebo” group to cross reference along with the untreated group, to see if there were any changed from just the injection and not what was in the injection.