Marcia I. Endres, Extension Dairy Scientist

April 28, 2007

I recently watched an animated movie entitled ‘Happy Feet’ where the main character (a penguin named Mumble) is trying to communicate with the ‘aliens’ (i.e. humans) who are taking most of their fish from the sea and causing their penguin colony to starve. He wanted to talk to these ‘aliens’ and plead them not to do it. He realized, after a few days at the marine park exhibit where he ended up when trying to find the ‘aliens’, that they did not speak ‘penguin’ and he could not convey his message by speaking to them. But he later called their attention and communicated by tap dancing, since he was a special penguin who knew how to dance; as a result, he ended up saving his colony from starvation.

Do cows try to ‘speak’ to us humans too? We don’t speak ‘cow’ either, but maybe there are some ways cows can convey to us whether or not they are doing well with the environment we provide them. Rick Grant, President of the Miner Institute in Chazy, NY, recently spoke at the Northeast Ag and Feed Alliance Ruminant Health-Nutrition Conference in Syracuse, NY, about research conducted in North America on the relationship between stocking density and natural cow behavior. It has been shown that at densities of 120% (20% more cows than stalls in the pen) or greater for lactating cows, resting was reduced by 12 to 27%, eating time was not affected greatly, cud chewing was reduced by up to 25%, and standing time was increased by 15 to 25%.

Grant and his group recently conducted a study at Miner Institute evaluating the effect of 100, 115, 130 or 145% stocking density of stalls and feed bunk on production and behavior of lactating cows. The study was conducted in the fall, when temperatures are more ideal for cows. In their study, lying time was reduced by about 1.1 hours per day between 100 and 145% stocking rate. Milk yield dropped from 95.9 to 91.5 pounds per day. Total feeding time was unaffected and averaged about 5 hours per day. They found no change in dry matter intake for the various stocking densities, but number of meals per day was reduced by one full meal between 100 and 145% stocking rate. This means that at greater stocking densities, cows had to eat faster. Slug feeding has been associated with ruminal acidosis. Milk fat percentage was depressed as stocking rate increased.

They also noted a trend for increased somatic cell counts with greater stocking rates. First calf heifers and lame cows were more affected by greater stocking density. The difference in milk production between heifers and cows increased from 6 pounds at 100% stocking density to about 15 pounds at greater stocking densities. As stocking density increased, milk production of lame cows was greatly reduced compared with non-lame cows. From 100% to 130%, this difference in milk production increased by 26 pounds per day.

Grant made some calculations for margin per cow based on the results of their study. He concluded that the rate of return was lower at lower and higher stocking densities and the highest returns were closer to 120% stocking density. The rate of return dropped off at 130% and basically nose dived at 145%. This response will probably vary for each dairy depending on management practices employed.

What about those special cows in our herds? Transition cows are more severely affected by overcrowding. It has been recommended to keep pen stall density at 80 to 90% and feed bunk space at 3 ft per cow for close-up dry and fresh cows. Those groups of cows can’t compete as well for resources and can really benefit if given the opportunity to transition the best way possible. We are talking about significant improvements in subsequent milk production and reduction of metabolic diseases. University of Wisconsin researchers have shown a reduction of 1.6 pounds of milk per day for each 10% increase in prefresh stocking density above 80% for first calf heifers. Feed intake was remarkably reduced in another study when feed bunk density was greater than 90%. Other studies have shown increases in the incidence of abomasal displacements after calving whenever the feed bunk stocking density was greater than 90%. Higher stocking density could also contribute to increased lameness incidence in early lactation (cows prefer to have ‘happy feet’ too). It is also recommended to keep prefresh and fresh heifers separated from older cows if possible. Paying more attention and providing a better environment (with 80 to 90% stocking density) for these transition animals can really help the financial bottom line.

Our cows will ‘speak’ to us and let us know that they appreciate what we are doing for them with the results being extra milk in the tank and better health (equals more $)!