1849
BODY CONDITION SCORE ASSESSMENT IN A GRAZING JERSEY HERD IN COSTA RICA
The aim of this research was to carry out a body condition score (BCS) observational study in a commercial grazing Jersey herd in Costa Rica (9º55ۥ N, 83º51ۥ W, 2350 m of altitude). The study comprised 5864 BCS records from 122 cows (29 primiparous and 93 multiparous) over a 16 months period. Cows were scored weekly by the same person from 9th wk prepartum to 43th wk postpartum. The 1 to 5 points scale was used (1= emaciated, 5= obese). Animals feeding practices were based on intensive grazing of 30 d regrowth kikuyu (Kikuyuocloa clandestina) (14.8% DM, 23.4% CP, 54.0% NDF, 25.7% ADF, 1.4 Mcal/kg NEL (3x), 2.2% Lignin) and supplementation of a balanced concentrate according to physiological stage. During the close up period animals were fed 4 kg of concentrate daily (14% CP, 1.7 Mcal/kg NEL(1x), 35% Starch, 0.2% Ca), and during lactation 1 kg of concentrate (18.6% CP, 1.9 Mcal/kg NEL, 48% Starch, 1.0% Ca)/2.5 to 3 kg of milk. Primiparous and multiparous cows BCS at calving was 4 points (95% CI: 3.80-4.22 points) and 3.8 points (95% CI: 3.71-3.94 points) respectively. BCS nadir after calving differed (P<0.05) between primiparous (3.1 points, 95% CI: 2.97-3.23 points) and multiparous cows (2.9 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 found in nadir extreme values within primiparous or multiparous groups of cows. Values were 2.63, 2.94 and 3.29 points for primiparous and 2.27, 2.78 and 3.20 points for multiparous, respectively. Likewise, the average BCS change differed (P<0.01) between extreme values in the same group, showing -0.25, -0.81 and -1.19 points for primiparous and -0.71, -0.93 and -1.21 points for multiparous cows in the same order. BCS at calving in primiparous cows was correlated with nadir (r=0.65, P<0.001) and BCS change (r=-0.76, P<0.001). Similarly, BCS at calving in multiparous cows was correlated with nadir (r=0.62, P<0.001) and BCS change (r=-0.55, P<0.001). Cows that calved with higher BCS, lost more BCS postcalving, but remained at a greater BCS at nadir and the whole lactation. Results suggest that BCS at calving could be used as a partial indicator of BCS nadir and BCS change from calving to nadir; which has important implications on production and fertility of cows. However more research should be done to extend these findings to wider populations.
Keywords: BCS, Body condition score, grazing Jersey cows