The aim of this research was to carryout a body condition score (BCS) observationalstudy in a commercial grazing Jersey herdin Cartago, Costa Rica (9°55` N, 83°51` W,2350 m of altitude). The study comprised5864 BCS records from 122 cows (29primiparous and 93 multiparous) over an 18months period. Cows were scored weekly by thesame person, from 9<span name="style_sup">th</span> week prepartum to 43<span name="style_sup">th </span>week postpartum. The 1 to 5 points scale wasused (1=emaciated, 5=obese). Animal feedingpractices were based on intensive grazing of 30d regrowth kikuyu (<span name="style_italic">Kikuyuocloa clandestina</span>)and supplementation of a balanced concentrateaccording to physiological stage. Primiparousand multiparous cows BCS at calving was 4.01points (95% CI: 3.80-4.22 points) and 3.83 points(95% CI: 3.71-3.94 points) respectively, BCSnadir after calving differed (p&lt;0.05) betweenprimiparous (3.10 points; 95% CI: 2.97-3.23points) and multiparous cows (2.86 points; 95%CI: 2.76-2.96 points). When stratifying BCS at calving into values ≤3.25, 3.50 to 4.00 and≥4.25 points, differences (p&lt;0.01) were foundin nadir and BCS change extreme values withinprimiparous or multiparous groups of cows.Animals that calved with higher BCS lost moreBCS post calving, but remained at a greaterBCS at nadir and the whole lactation. Results suggest that BCS at calving could be used as apartial indicator of BCS nadir and BCS changefrom calving to nadir, which has importantimplications on production and fertility of cows.)and supplementation of a balanced concentrateaccording to physiological stage. Primiparousand multiparous cows BCS at calving was 4.01points (95% CI: 3.80-4.22 points) and 3.83 points(95% CI: 3.71-3.94 points) respectively, BCSnadir after calving differed (p<0.05) betweenprimiparous (3.10 points; 95% CI: 2.97-3.23points) and multiparous cows (2.86 points; 95%CI: 2.76-2.96 points). When stratifying BCS at calving into values ≤3.25, 3.50 to 4.00 and≥4.25 points, differences (p<0.01) were foundin nadir and BCS change extreme values withinprimiparous or multiparous groups of cows.Animals that calved with higher BCS lost moreBCS post calving, but remained at a greaterBCS at nadir and the whole lactation. Results suggest that BCS at calving could be used as apartial indicator of BCS nadir and BCS changefrom calving to nadir, which has importantimplications on production and fertility of cows.

Body condition score; grazing dairy cows; energy reserves mobilization