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Association between automated body condition scores and fertility of Holstein cows.

P. Pinedo

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06-23-2020

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Abstract:

T86
Association between automated body condition scores and fertility of Holstein cows.
B. Klug1, D. Manriquez1, A. Ayyangar1, A. DeVries2, S. Granz3, P. Pinedo*1. 1Colorado State University Fort Collins, CO, 2University of Florida Gainesville, FL, 3DeLaval Tumba, Botkyrka, Sweden.

The objective was to analyze the association between body condition score (BCS) and BCS changes (δBCS) at multiple time points during lactation and subsequent fertility. Data were collected from Holstein cows (n = 4,479) in 1 herd in CO, USA (April—December 2019). BCS at 7, 21, and 60DIM and at the d of AI1 (dAI) were obtained from the DeLaval Body Condition Scoring-BCS camera system. BCS (0.1 points intervals/5point scale) were categorized as low (L; mean +SD), intermediate (M; mean � SD), and high (H; > mean +SD). Cows were also classified by δBCS (gained [GN], no change [NC], mild loss [ML; −0.1 to −0.39], and moderate loss [MOL; < −0.40]) combining multiple time points. Average milk up to 90 DIM (M90) was calculated. Cows were milked 3x and subject to AI following a double OvSynch protocol. Outcomes included pregnancy at AI1 (PAI1) and hazard ratio for conception. Data were analyzed by logistic regression and survival analysis. Calving season (summer vs. other), parity category (1 [n = 2,308]; ≥ 2 [n = 2,171]), and M90 were included in the models. Overall PAI1 was 40.6%. The odds (95%CI) of PAI1 were 1.75 (1.25—2.47) and 1.50 (1.20—1.86); 1.57 (1.20—2.08) and 1.86 (1.49—2.32); 1.93 (1.32—2.84) and 1.56 (1.30—1.87); and 1.48 (1.07—2.06) and 1.77 (1.43—2.20) times greater for cows in H and M vs. cows in L at 7DIM, 21DIM, 60DIM, and at dAI, respectively. PAI1 was associated with δBCS from 7 to 21DIM (GN = 46.2%, NC = 39.8%, ML = 42.0%, MOL = 26.5%; P = 004), from 7 to 60 DIM (54.3%, 49.0%, 44.9%, 33.0%; P < 0.01), from 21 to 60 DIM (44.6%, 46.4%, 38.9%, 21.4%; P < 0.001), and from 21 DIM to dAI (50.1%, 42.9%, 39.3%, 20.1%; P < 0.001). The hazard ratio for conception in cows with MOL between 7 to 21DIM, 7 to 60DIM, 7 to dAI, and 21 to 60DIM were 0.49, 0.58, 0.54, and 0.38 relative to cows in GN (P < 0.05). In conclusion, low BCS and excessive loss of BCS were associated with lower PAI. Monitoring daily automatic BCS scoring provides valuable information for the assessment of risk of conception.

Keywords: Holstein, BCS, reproduction.