Comparison of disease occurrence between grazing and zero-grazing dairy cows at northern area in Hokkaido.

Abstract

To evaluate for an effect of grazing on a health in dairy cattle, the veterinary records from Agricultural Cooperation were analyzed with milk production records and feeding styles with or without grazing for each dairy farms at northern area in Hokkaido, Japan. The veterinary records and milk production performance for each farm were from Research Center of Agriculture and Science in this area. Number of cattle kept, area of grassland, grazing or zero-grazing were surveyed by a postal questionnaire method for all dairy farms, about 100, in this area. Forty-six questionnaires had been obtained. In these farms, means of milk yield, number of milking cows, area of grazing pastures and number of medical treatments by veterinarians were 8,127.2 kg/305d, 71.7 cows, 8.6 ha and 1.2 time/year, respectively. The number of medical treatments by veterinarians/cow/year were positively related to the milk yield /cow/305d. (P<0.05) and negatively related to the area of grassland/farm (P<0.05). From this 46,32 farms were picked up for further analysis. Grazing were used in 24 farms, in which 7 farms were of all-day-grazing except milking time (group G), 17 were grazed their cattle during day time (group TG). Remained 9 had kept their animals in their cow-shed for a whole day (group B). There was no statistical difference of milk yield/cow among groups. The number of medical treatments (/cow/year) for milk organs by veterinarians was a little high in the group G and treatment frequencies for a foot and hoof were relatively low in groups G and B, though those differences among groups were not significant. Frequency of veterinary treatments (/cow/year) for conception, calving and reproductive organs was lower in group G (0.22) than groups TG (0.41) and B (0.42) significantly (P<0.05).