Milk protein/fat ratio on day 7 postpartum as a predictor of left displacement of abomasum

Left displaced abomasum (LDA) affects high-yielding dairy cattle, but the aetiopathogenesis for this condition is not clearly understood. Studies conducted on the aetiology of LDA have recognised breed, age, diet, genetics and metabolic disorders as factors that can predispose dairy cows to developing LDA (Coppock 1974, Varden 1979). Specifically, negative energy balance and ketosis are among the many factors implicated in the aetiopathogenesis of LDA (LeBlanc and others 2005). By monitoring energy balance in postpartum dairy cattle via the milk protein/fat (P/F) ratio, it is possible to identify cows predisposed to LDA. In addition to the negative energy balance, sub-acute ruminal acidosis plays an important role in the aetiopathogenesis of LDA because the flow of rumen-derived gases (CO2 and CH4) and excess volatile fatty acids from the rumen to the abomasum increases the abomasal pH, enabling bacterial fermentation and resulting in additional gas production (Svendsen 1970, Gregory and Miller 1989). Milk fat and protein levels and the ratio between the two are often used to monitor energy balance in postpartum cows (Gantner and others 2009). Geishauser and others (1997) previously investigated the relationship between P/F ratios and abomasal displacement, but they used different sample collection times from those used in the work presented here. Standardisation of sampling times could improve the accuracy of milk P/F ratios, resulting in a more reliable indicator for LDA, especially in herds where development of the condition is related to ketosis. This study aimed to evaluate the milk P/F ratio as a potentially cheap, useful and accurate predictive tool for LDA. High-yielding dairy cows (n = 154) in their second lactation and without a …