Small Group Housing and Illness
Real, on-farm conditions for research. Unusual but welcome.
"Group housing of Holstein calves in a poor indoor environment increases respiratory disease but does not influence performance or leukocyte responses." C. J. Cobb and Others, Journal of Dairy Science, 97:3099-3109, May 2014.
These were well managed calves (excellent colostrum management, very good blood serum total protein values, 2.2 pounds of 28-20 milk replacer fed daily, ad lib. water and calf starter grain) in a very common farm housing situation - the approximately 100 x 70 barn had only two sidewall openings of 12' x 9'.
Calves were in pens that provided about 23 square feet per calf. The three compared treatments were 1 calf in a 6' x 3.8' pen, 2 calves in a pen double that size and 3 calves in a pen triple that size.
Health and mortality:
% treated % Died
for resp. disease
1 calf per pen 10 7
2 calves per pen 23 23
3 calves per pen 34 17
These calves were in a poorly ventilated barn in the summer, humidity ran around 74% and temperatures varied from 67F to 94F. You can imagine the air borne pathogen load in this barn. Evidently being housed with other calves seemed to be the straw that broke the camel's back for respiratory infections. My observations is that only good colostrum management and nutrition kept the infection rates as low as they were.
No observed differences among the three housing arrangements either during the preweaning period or out to 161 days of age.
There was an interesting profile of growth rates during the preweaning period. By the end of three weeks the calves had ramped up to 1.8 pounds per day.
Then, (no explanation given in research report) growth rates dropped to about 1.1 pounds per day from 21 to 54 days of age. There was not mention of milk refusals so I have to assume all the calves drank their milk (fed 2X with 3 quart bottles). However, when one looks at calf starter intake, even at 5 weeks of age the calves were averaging less than 1/2 pound of starter daily.
That starter intake matches my experience - under hot humid conditions and plenty of milk replacer powder calves just lag on eating their starter. The poorly ventilated barn just made a bad situation worse.
Bottom line? Poor facilities compounded with elevated pathogen exposure can overcome good colostrum management and nutrition.