Activity and rumination in an organic vs. a conventional grazing herd

Abstract Text:

The objectives of this study were to evaluate activity and rumination of organic and conventional Holstein and crossbred cows during the grazing and winter months and to investigate the correlation between ambient air temperature and daily rumination and activity. The study was conducted for  2 years (March 2014 to March 2016) at the University of Minnesota West Central Research and Outreach Center, Morris grazing dairy.  During the grazing season (May to October) organic cows were on pasture and supplemented with 2.72 kg of corn per cow per day whereas conventional cows were supplemented with a TMR of corn silage, alfalfa haylage, corn, soybean meal, and minerals. During the winter season, both organic cows and conventional cows were supplemented with a TMR. Activity and rumination time (daily and 2-h periods) were monitored electronically using HR-LD Tags (SCR Engineers Ltd., Netanya, Israel) for the 2-yr period. Activity is reported in “activity units” from SCR DataFlow II software.  The PROC MIXED of SAS was used for statistical analysis, and independent variables were herd (conventional or organic), month (January to December), year and their interactions, and date was a random effect.  Daily activity was greater (P < 0.05) for the organic herd compared to the conventional herd (544 vs. 533), respectively. Daily rumination (min/d) was also greater (P < 0.05) for the organic herd (553 min/d) compared to the conventional (538 min/d) herd.  Daily activity was greatest (P < 0.05) during July (791) and least during January (334) for the organic herd, and greatest (P < 0.05) during July (752) and least during January (289) for the conventional herd. Daily rumination was greater (P < 0.05) during December (592 min/d) compared to July (482 min/d) for the organic herd, and was greater (P < 0.05) during December (563 min/d) compared to March (496 min/d) for the conventional herd.  Greater daily rumination of cows on a herd basis was negatively correlated (-0.39) with increased (P < 0.01) ambient air temperature in the organic herd, and there was a slight negative correlation (-0.10, P< 0.01) of daily rumination and air temperature in the conventional herd.  In summary, organic cows had greater daily activity, and greater daily rumination compared to conventional grazing cows.  Monthly activity and rumination patterns of grazing organic and conventional dairy cattle in this study were influenced by the weather.

Keywords: rumination, organic, activity