Negative energy balance: The association between elevated milk fat to protein ratio in days postpartum, pregnancy per AI to first service and postpartum diseases in dairy cattle.
Burgwal, N.S. van de
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Abstract The first objective of this study was to find a possible association between elevated milk fat to protein ratio (FPR) in days postpartum and pregnancy per artificial insemination (AI) to first service. To find a possible association between postpartum diseases and FPR in dairy cattle, was the second objective of this study. Data collected from 1200 Holstein Frisian milking cows were used in this study. Daily milk fat to protein ratios were collected from each cow up to 21 days in milk (DIM) for the first objective. A FPR>1.5 measured in more than 1,2,3,4 or 5 days within 21 DIM were collected. Pregnancy loss and time to pregnancy within 300 DIM were collected. For the second objective, data was collected in the first 30 days after parturition for presence of the postpartum diseases metritis, ketosis, displaced abomasum (DA), indigestion and mastitis. In statistical analysis no significance was found for FPR in more than 1, 2, 3, 4 or 5 days within 21 DIM. For this reason, one or more days was chosen for further analysis since the number of cows were most equally distributed between low and high FPR and pregnancy per AI to first service. Chi-square and multiple logistic regression analysis were used to find a possible association between the variables. No significant outcome between FPR>1.5 for one or more days during the first 21 DIM and pregnancy to first AI. An association was found for the postpartum diseases DA, metritis and ketosis with FPR>1.5. No significant association was found between mastitis and FPR>1.5, and indigestion and FPR>1.5. In this study FPR was not found to be a significant indicator to predict pregnancy per AI to first service. Postpartum diseases are associated FPR and therefore can aggravate negative energy balance (NEB) during early lactation.