Table 4.

Fractional rate of passage from the rumen (k₁) and hind gut (k₂), transit time (TT) and total mean retention time (TMRT) of liquid and particle phases of digesta in lactating dairy cows fed on Napier grass (NG) or Brachiaria brizantha cv. Piatá (PG), unsupplemented or supplemented with Desmodium distortum (NGD and PGD, respectively).

Parameters1	NG	NGD	PG	PGD	RMSE	Significance2
(n = 32)						Grass	DD	Grass × DD
Fluid phase
k1, /h	0.04	0.04	0.04	0.05	0.006	NS	*	NS
k2, /h	0.06	0.11	0.15	0.1	0.046	NS	NS	*
TT, h	2.5	0.7	1.1	2.0	1.59	NS	NS	NS
TMRT, h	46.5	35.4	37.6	34.7	5.26	NS	*	NS
Particle phase
k1, /h	0.02	0.03	0.03	0.03	0.005	NS	**	NS
k2, /h	0.03	0.06	0.06	0.06	0.017	NS	NS	NS
TT, h	2.4	2.1	1.8	2.3	2.19	NS	NS	NS
TMRT, h	83.1	49.7	62.8	50.7	7.77	*	***	*

n = the number of observations; NG = Napier grass; NGD = Napier grass + Desmodium distortum; PG = B. brizantha cv. Piatá grass; PGD = B. brizantha cv. Piatá + Desmodium distortum; RMSE = root mean standard error; DD = Desmodium distortum.

*: P < 0.05; **: P < 0.01; ***: P < 0.001; NS: P > 0.05.

¹k₁ is proportion per hour at which particles pass out of the rumen; k₂ is proportion per hour at which large particles are reduced to small particles within the rumen.

²Grass: effect of NG and PG; Grass × DD: interaction effect of grass and DD.