Reticular groove functionality in adult cattle and evaluation of alternative techniques for preparation, infusion and sampling of ruminal fluid phase markers

The objectives of this work were to determine the functionality of the reticular groove in adult cattle and to evaluate alternative techniques for preparation, infusion and collection of ruminal dynamics markers. Four cows with rumen cannulas were used in three experimental assays. In the first assay the water percentage that passed directly to the omasum (27.39%) tended to be lower (P = 0.14) than the water percentage that reached the reticulorumen (72.61%), indicating inefficient functioning of the reticular groove in adult bovines. In assay 2, the fractional rates estimated simultaneously by Cr-EDTA (14.79 % h-1) and Co-EDTA prepared for an alternative technique (14.76% h-1) did not differ (P = 0.96). The exponential regressions had a high determination coefficient (r(2) = 0.90). The Co: Cr ratio in the ruminal fluid did not differ during the four hour sampling period (P = 0.68). There was no variation in the Co: Cr ratio in urine or feces. The simple technique proposed for the preparation of Co-EDTA, was effective. In assay 3, markers were infused into digesta without homogenization. The best plotting (r(2) = 0.88; P < 0.001) of the exponential regression was obtained by excluding the five initial collection times (1.67 h after infusion) and by doubling the sampling intervals until 5.33 h after infusion. Under this collection pattern, the exponential regression determination coefficients did not differ (P = 0.17) from the standard curves (r(2) = 1), when hypothetically compared. The alternative techniques proposed for infusion and sampling are viable, but require validation.