Effects of Peptein supplementation on ruminal microbiota and in situ feed degradability in dairy cows

The study objectives were to evaluate the performance of Peptein (APC Europe, Spain), a protein hydrolysate derived from red blood cells with two different degrees of hydrolysis, either high (HDH) or low (LDH) as a N source for rumen microbial growth in comparison with other N supplements including pork peptone, fish peptone, soy peptone, and spray dried red blood cells (SDRBC), and to determine the potential consequences on feed degradation in the rumen. In Experiment 1, four replications of Tilley Terry incubations with all N sources providing an isonitrogenous supply of 0.3g of N were performed from rumen aliquots obtained from 3 cows. Quantification of Gram positive and Gram negative bacteria was estimated by real time-PCR. In experiment 2, 8 rumen-cannulated cows received an equivalent of 44.8g/dN from either 320g/d of Peptein HDH (n=4) or 100g of urea (n=4 cows) for a 12-d period while dry and later when lactating via a rumen cannula split in 2 portions of 160g for 12 d. On day 10, in situ bags containing 0.8±0.06g of corn, soybean hulls, alfalfa, or beet pulp were placed in the rumen for 2, 4, 8, 12, 16, 24, and 48h. In Experiment 1, Peptein HDH and LDH and pork peptone increased (P<0.05) the quantification of Gram negative bacteria in the rumen fluid compared with the other peptones and SDRBC, but quantification of Gram positive bacteria was unaffected by treatments. In Experiment 2, the effective rumen degradation of DM from beet pulp in dry cows supplemented with Peptein HDH (681±11.1g/kg) tended (P=0.07) to be greater than when incubated in unsupplemented dry cows (646±11.1g/kg). In lactating cows, the effective rumen degradation of CP and aNDFom from corn was greater (P<0.05) when supplementing Peptein HDH (527±9.6 and 448±2.3g/kg, respectively) than when no supplementation was provided (446±9.6 and 375±2.3g/kg, respectively). It is concluded that, compared with SDRBC, and fish and soy peptones, Peptein HDH improves proliferation of Gram negative without affecting those of Gram positive bacteria in the rumen, and improves rumen degradation of CP and aNDFom from corn in both dry and lactating cows.