Abstract #248

Section: Ruminant Nutrition (orals)
Session: Ruminant Nutrition Platform Session: Probiotics, Prebiotics, and Postbiotics: Gut Health and Beyond
Format: Oral
Day/Time: Monday 4:15 PM–4:30 PM
Location: Junior Ballroom A

# 248
Lactobacillus plantarum as direct-fed microbial in high-producing dairy cow diets.
H. F. Monteiro^*1, A. L. J. Lelis², V. L. N. Brandão¹, A. Faccenda³, A. S. Avila⁴, J. Arce-Cordero¹, L. G. Silva¹, X. Dai¹, R. Restelatto⁵, P. Carvalho⁶, L. R. Lima⁶, A. P. Faciola¹, ¹Department of Animal Sciences, University of Florida, Gainesville, FL, ²Departamento de Zootecnia, Universidade de São Paulo, Pirassununga, SP, Brazil, ³Departamento de Zootecnia, Universidade Estadual de Maringá, Maringá, PR, Brazil, ⁴Departamento de Zootecnia, Universidade Estadual do Oeste do Paraná, Marechal Cândido Rondon, PR, Brazil, ⁵Departamento de Zootecnia, Universidade Federal do Paraná, Curitiba, PR, Brazil, ⁶Departamento de Zootecnia, Universidade Federal do Mato Grosso, Cuiabá, MT, Brazil.

The objective of this study was to evaluate the effects of Lactobacillus plantarum as direct fed microbials (DFM) in high-producing dairy cows’ diets on ruminal fermentation and N metabolism in vitro. A dual-flow continuous culture system was used in a replicated 4 × 4 Latin square design. A basal diet was formulated to meet the requirements of a cow producing 45 kg of milk/d (16% CP and 28% starch). There were 4 experimental treatments: the basal diet without any DFM (CTRL); a mix of Lactobacillus acidophilus 1 × 10⁹ cfu/g and Propionibacterium freudenreichii 2 × 10⁹ cfu/g (MLP = 0.01% of diet DM); and 2 different inclusion levels of L. plantarum 1.35 × 10⁹ cfu/g (L1 = 0.05% and L2 = 0.10% of diet DM). The DFM contained both carrier and microbes. The MLP treatment was used as an intermediate treatment containing bacteria that produce and utilize lactic acid, while L1 and L2 only produce lactic acid. The ¹⁵N isotope was used as a microbial marker. Data were analyzed using linear and nonlinear mixed models; orthogonal contrasts were used to compare treatment means. The fermentation pH, lactate concentration, true digestibility of nutrients, and total VFA concentration were not different across treatments. All DFM treatments decreased NH₃-N concentration although no other major difference in N metabolism was observed. The L1 treatment tended to have a greater propionate molar proportion compared with L2. In sum, all DFM tested decreased ruminal NH₃-N in vitro, which suggests a better N utilization in the rumen. Table 1 (Abstr. 248). Effects of lactic acid-producing DFM on ruminal nitrogen metabolism in vitro

Item	Treatment				SEM	P-value
CTRL	DFM
MLP	L1	L2	CTRL vs. DFM	MLP vs.L1/L2	L1 vs. L2
NH₃-N, mg/dL	15.4	14.1	14.3	14.7	0.46	0.05	0.53	0.51
N flows, g/d
Total N	2.73	2.76	2.79	2.75	0.06	0.59	0.92	0.62
NAN	2.10	2.17	2.21	2.17	0.07	0.35	0.96	0.51
Bacterial-N	0.84	0.86	0.90	0.82	0.04	0.59	0.99	0.11
RDP-N	1.75	1.71	1.71	1.69	0.05	0.37	0.91	0.72
RUP-N	1.27	1.31	1.30	1.33	0.05	0.35	0.99	0.70
Eff. of N utilization, %	47.9	50.3	53.2	48.6	3.00	0.42	0.87	0.25
Bacterial efficiency, g/kg	14.0	14.7	15.3	13.8	0.81	0.51	0.87	0.17

Key Words: lactic acid bacteria, starch, nitrogen metabolism

Speaker Bio

Hugo Monteiro graduated in Animal Sciences at State University of Maringa in Brazil, and is currently pursuing his PhD at the University of Florida, under advisory of Dr. Antonio Faciola. In his PhD studies, Monteiro has been dedicated in evaluating the effects of direct fed microbials on ruminal fermentation and the microbial community composition of the rumen. Monteiro has also worked in setting up a new dual-flow continuous culture system at Faciola’s lab, and his future research goals include studying in vitro techniques in order to better understand the ruminal fermentation and microbial interactions in the rumen.