NUTRITIONAL RISK-FACTORS IN THE ETIOLOGY OF LEFT DISPLACED ABOMASUM IN DAIRY-COWS - A REVIEW

The transition period occurring 2 wk prepartum through 2 to 4 wk postp artum is the major risk period in the etiology of left displaced aboma sum. The prepartum depression of intake and the slow postpartum increa se in intake are risk factors causing lower ruminal fill, reduced fora ge to concentrate ratio, and increased incidence of other postpartum d isorders. Uncomplicated ketosis, retained placenta, metritis, and hypo calcemia at parturition are risk factors for left displaced abomasum. Excessive amounts of concentrate during the prepartum period increase the risk of left displaced abomasum, which may occur from the lower ru minal fill caused by greater prepartum intake depression and reduced f orage to concentrate ratio, decreased ruminal motility from lower rumi nal fill and higher volatile fatty acid concentration, and decreased a bomasal motility and emptying from higher concentrations of volatile f atty acids. Effects of volatile fatty acids on motility may be exacerb ated by low ruminal absorption of volatile fatty acids during the tran sition period. Minimal intake of concentrate during the prepartum peri od may increase the risk of left displaced abomasum through failure to increase the absorptive capacity of the ruminal papillae and failure of the microbial population of the rumen to adapt prior to the intake of high energy postpartum diets. Increased risk of left displaced abom asum in cows that are hypocalcemic at parturition may be due to decrea sed ruminal and abomasal motility.