Abstract #32
Section: ADSA Production MS Oral Competition (Graduate)
Session: ADSA Graduate Student (MS) Production Oral Competition
Format: Oral
Day/Time: Monday 11:15 AM–11:30 AM
Location: 309
Session: ADSA Graduate Student (MS) Production Oral Competition
Format: Oral
Day/Time: Monday 11:15 AM–11:30 AM
Location: 309
# 32
Using in-line milk progesterone data to characterize luteal activity parameters associated with reduced fertility in dairy herds.
T. C. Bruinje*1, M. G. Colazo2, M. Gobikrushanth1, D. J. Ambrose1,2, 1Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, 2Livestock Research Section, Alberta Agriculture and Forestry, Edmonton, AB, Canada.
Key Words: estrous cycle, progesterone profile, reproductive efficiency
Using in-line milk progesterone data to characterize luteal activity parameters associated with reduced fertility in dairy herds.
T. C. Bruinje*1, M. G. Colazo2, M. Gobikrushanth1, D. J. Ambrose1,2, 1Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, 2Livestock Research Section, Alberta Agriculture and Forestry, Edmonton, AB, Canada.
Using milk progesterone (mP4) data, this observational retrospective cohort study investigated characteristics of (1) commencement of luteal activity (CLA), (2) luteal phase (LP) length, (3) mP4 concentration pre-AI, and (4) interval from cessation of LP to AI, influencing AI outcomes. Records of mP4 (n = 153,156) obtained by an in-line milk analysis system (Herd Navigator, DeLaval) from 1,240 Holstein cows (2,354 lactations) in 4 Alberta farms were evaluated. Sampling started at 21.5 ± 4.0 DIM (Mean ± SD) and repeated every 2.3 ± 2.0 d. Luteal activity (LA) was determined by mP4 level ≥5 ng/mL and LP as period of LA until an mP4 decline (<5 ng/mL). Outcomes of AI were presumed based on interval from AI to mP4 decline of ensuing LP as not pregnant (≤30 d), pregnant (≥ 50d) or pregnancy loss (PLOSS; 31 to 50 d). Days to CLA and first LP length were evaluated for 1,439 first AI. Length of pre-AI LP, mP4 concentration pre-AI (at mP4 decline), and interval from mP4 decline to AI were evaluated in 4,526 AI. Data were analyzed using PROC GLIMMIX (SAS) and models included parity, milk yield and DIM as fixed and farm as random effects, with cow as repeated measure. Only significant (P ≤ 0.05) results are presented. Overall proportions of pregnancy per AI (P/AI) and PLOSS were 24.8% (17–48% among farms) and 29.8% (17–32% among farms). Odds of P/AI was lower in multiparous than in primiparous cows (odds ratio [OR] = 0.34). Having CLA ≥56 DIM decreased P/AI (OR = 0.15) and increased PLOSS (OR = 6.67) compared with earlier CLA. Having first LP of >17 d decreased P/AI (OR = 0.18) and increased PLOSS (OR = 9.09) compared with shorter LP. Pre-AI LP of >16 d reduced P/AI (OR = 0.43) and increased PLOSS (OR = 6.67) compared with pre-AI LP ≤16 d. Pre-AI mP4 > 0.5 ng/mL reduced P/AI (OR = 0.68) and increased PLOSS (OR = 1.64) compared with lower mP4. Interval from mP4 decline to AI >1.5 d reduced P/AI (OR = 0.61) compared with shorter interval. Based on mP4 profiles, we identified characteristics of LA affecting fertility as: (1) delayed CLA, (2) prolonged first or pre-AI LP, (3) high mP4 pre-AI, and (4) delayed AI after mP4 decline.
Key Words: estrous cycle, progesterone profile, reproductive efficiency
