Preference of Dairy Cows for Free-Stalls Bedded with Sand or Granite Fines and Changes in Bacterial Counts in Those Materials

Sand and granite fines were compared as bedding in free stalls for lactating cows. Eighteen stalls were randomly bedded with sand or granite fines. Lactating cows [100 to 160; 31 to 90 d in milk (DIM)] had access to these stalls plus 142 other stalls bedded with sand. Experimental stalls were observed on 6 d (4 times/d) during the 27-d study. Using a logistic procedure, experimental stalls bedded with sand were 2.8 times more likely to be used than those bedded with granite fines (P<0.01). Stall usage was analyzed using a frequency procedure (P<0.001); cows were observed lying on sand 90% of the time and on granite fines 73% of the time. On d 24, hardness of the surface, measured at a pressure of 2 kg/cm2, was greater for granite fines (P<0.01). On d 0 and 1, Streptococci spp. counts in granite fines and sand did not differ; however, on d 7 and 11 after adding new materials, Streptococci spp. counts in granite fines were greater than in sand (bedding material × time of sampling interaction, P<0.05). Cows preferred sand to granite fines in free stalls, possibly because sand was the softer bedding surface. Streptococci spp. counts were less in stalls bedded with sand on d 7 and 11 after cows had used the bedding. Costs (without shipping) of sand were $0.096/d compared with $0.049/d for granite fines.