Effects Of Supplementation With A Pichia Guilliermondii Yeast Cell Product Or Essential Oils On Performance And Health Of Dairy Calves During An Experimental Coccidial Infection

Objective: This study was conducted to determine whether an inactivated whole-cell yeast product derived from Pichia guilliermondii (PG; CitriStim, Pancosma, a brand of Archer Daniels Midland Co.) or an essential oil blend (EO) primarily composed of carvacrol and cinnamaldehyde (Pancosma, a brand of Archer Daniels Midland Co.) could be used to mitigate the severity of an experimental coccidial infection in young dairy calves.Materials and Methods: A 10-wk experiment was conducted using 38 Holstein bull calves (39.5 +/- 5.7 kg) fed a typical commercial 20:20 milk replacer (Dairy Manufacturers Inc.) regimen (500 g/d). Calves were randomly assigned to 1 of 5 treatments: uninfected control (PC) and 4 treatments that received experimental coccidial infections: infected control (NC; no additives); PG at 2 g/head per d (PG2); PG at 6 g/head per d (PG6); and EO at 0.28 g/head per d. Feed additives were provided in the milk replacer and supplementation started when calves were approximately 2 wk of age. On d 35 of the trial, each infected calf was administered a single oral dose of a mixed inoculum of 5 Eimerial oocysts. Calves were weighed upon arrival, before inoculation, and weekly before morning feeding. Fecal scores were visually monitored daily using a scoring system with a scale of 1 to 5. Body temperature was measured 1 per wk for 5 wk following inoculation. To assess oocyst numbers, beginning on d 4 postinoculation, feces were collected daily until d 35. To determine the extent of intestinal damage caused by coccidial infections, 1 calf per treatment was randomly killed on d 7 and 2 calves per treatment were killed on d 21 postinoculation.Results and Discussion: All infected calves scoured with equal severity, which was statistically significant when compared with noninfected calves (P < 0.05). Calves fed either PG6 or EO tended to have greater intake compared with NC and PG2 calves (6.65 and 6.52 kg vs. 2.92 and 2.94 kg, respectively; P = 0.057). In addition, gain tended to be greater for calves fed either PG6 or EO (16.7 and 15.4 kg) compared with NC and PG2 calves (P = 0.097). Fecal oocyst shedding peaked at 7 d (phase 1) and 21 d (phase 2) postinoculation. In phase 1, PG6 reduced (P < 0.05) oocyst counts compared with NC; however, by phase 2, oocyst counts did not differ across all infected calves. When lesion scores across all intestinal segments were analyzed, calves given either PG2 or PG6 had lower (P < 0.05) lesion scores than either NC calves or calves given EO.Implications and Applications: Calves supplemented with PG showed marked benefits on intestinal health, whereas calves supplemented with EO had modest benefits under coccidia infection. These data further suggest that natural feed additives may be alternatives for antibiotics during coccidiosis challenges.