Lameness is one of the most common and costly disorders affecting dairy cattle. Freestall housing systems are designed for ease of management but are also associated with a greater risk of hoof injury and disease leading to lameness.
Pasture rearing can improve hoof health, perhaps due to the change in the physical environment or to associated factors such as change in diet. Fewer cows become lame during the grazing season and cows kept outdoors are less prone to claw disorders than those that are housed indoors. Despite these advantages in hoof health, switching from indoor housing to pasture is not a practical option for many producers. But providing a rest period on pasture for lame cows may be a more practical option.
A study at the University of BC was designed to test whether a relatively short period on pasture would help lame cows recover by providing access to more comfortable standing and lying surfaces. The study tested whether providing lame cows a four week period of pasture would improve gait.
Eighteen groups, each of four lactating cows, were either kept in the same freestall barn or moved to pasture. The pasture was 24 hectares of orchard grass and Festuolium seeded three years earlier. Freestall housed cows were kept in pens that had six metres of accessible alley space and one stall per cow filled with 40 cm of washed river sand. Cross-over alleys were scraped daily and all other alleys were cleaned six times daily. All flooring outside the stall area was concrete.
Cows were gait scored before the experiment using a the UBC scoring system which assigns scores from 1 to 5. Gait was assessed at the start of the experiment and then weekly for four weeks immediately after the morning milking when cows were walking down the return alley.
To assess how much time cows spent lying down, electronic data loggers, attached to the hind leg of each cow, recorded each time each cow lay down, providing a very accurate and continuous measure of total time lying down and the number of lying episodes during each day.
As shown in the graph, average gait score increased from 3 to 3.2 over the four week study for the cows that stayed inside the barn. In contrast, gait improved rapidly for those cows that were moved to pasture. These cows also started the study with an average gait score of 3, but this score declined close to 2 after four weeks on pasture. In fact, the greatest improvements came during the first two weeks that cows were put outside.
Improvements in gait of the pastured cows were partly because of changes in joint stiffness. Concrete flooring, especially when covered with manure slurry, may not provide sufficient friction, causing slipping and resulting in cows walking with a ‘stiff’ gait. Improvements among cows on pasture may also have been caused by increased exercise. Pastured cows are required to spend more time walking because of grazing and distance from the parlour. Although it was expected that cows on pasture would spend more time lying down, the opposite was true—cows on pasture actually spent less time lying down (10.9 hours/day) than cows kept indoors (12.3 hours/day).
Interestingly, cows on pasture lay down and stood up more often than cows indoors (15.3 vs. 12.2 times per day), suggesting that these transitions are constrained by the stall structure. The reduced lying time on pasture may have been because cows preferred to spend time standing on this surface.
Omar Mendo et al., University of BC Animal Welfare Program