That standard is also important for cows. We know this based on milk quality data and health records, but recent research from New Zealand shows it also factors into cow comfort and behavior.

A study at the Ruakura Research Center in New Zealand provided three lying surfaces involving wood chips to gauge a cow’s aversion to wet and dirty surfaces. The study’s goal was to determine if it was the moisture content or the dirtiness that curtailed cows’ interest in a lying surface.

During the first phase of the study, 18 dry, pregnant cows had to lie on two of three surfaces for 18 hours per day with the remaining six hours being spent on pasture. The three surfaces were clean and dry (dry matter content of 44 percent), dirty (manure contaminated with 40 percent dry matter), and wet (23 percent dry matter).

Cows assigned to the wet surface spent the least amount of time lying when restricted to the wet surface (21 percent; 4.6 hours total per day) and the most time lying when on pasture (13 percent). Cows on the dirty surface spent considerably more time lying (57 percent; 10.6 hours per day) and less time lying while on pasture (4 percent). Cows restricted to the clean bedding spent the most time lying (64 percent; 11.7 hours per day) and only spent 3 percent of their time lying while on pasture.

In addition to that, cows on the wet surfaces spent virtually no time lying laterally, spent less time lying with their heads supported, and less time with their front legs tucked while lying. The researchers indicated this was a sign of poor-quality rest in addition to the limited rest that this group got.

In the second phase, cows were given a free choice between two surfaces for two consecutive days. Cows were allowed to select their lying preference and did so in the order of clean, dirty, and then wet. The researchers concluded in their Journal of Dairy Science article, “There is compelling evidence that wet surfaces impair the welfare of dairy cattle by affecting the quantity and quality of rest.”