Abstract #70

# 70
Production and dry mater intake of dairy cows in mid lactation with different allocation time at grazing in lucerne (Medicago sativa).
A. Santana*1, J. Dayuto1, M. García1, E. Salaberry1, C. Cajarville1, J. L. Repetto1, 1Instituto de Producción Animal de Veterinaria, Facultad de Veterinaria, Universidad de la Republica, Libertad, San José, Uruguay.

The aim of this study was to evaluate the effects of including one or 2 sessions at grazing in milk production and dry mater intake (DMI) in mid lactation dairy cows. Twelve multiparous Holstein cows with 584 ± 71 kg BW, 193 ± 83 DIM, were allocated in a cuadruplicated 3 × 3 Latin square with 3 treatments: (1) fed a total mixed ration (TMR) during 22 h (TMR + 0h), (2) fed TMR during 14 h plus 8 h of grazing alfalfa in one session after afternoon milking (TMR + 8h), or (3) fed TMR during 14 h plus two 4-h grazing sessions after each milking (TMR+4+4h). Each experimental period consisted in 12 d of adaptation and 7 d of sampling. Intake of TMR (difference by offered and rejected) and lucerne (cutting 5% of the area pre and post-grazing) were individually measured during 5 d of each period. Milk production was individually recorded for 5 d, and samples were taken during 2 d in both daily milkings to analyze milk composition. The results are shown in Table 1. The intake of pasture was near 37% of the total DM consumed. This inclusion did not affect neither milk production nor composition. Fractionating the grazing session lead to higher intake of pasture. Table 1.
TMR+0hTMR+4+4hTMR+8hSEMTreatmentPeriod
DMI (kg/d)
 Lucerne0c8.18a6.99b0.2660.00010.8265
 TMR23.26a13.51b12.43b0.8010.00010.0016
 Total23.26a21.7ab19.41b0.8390.02590.0059
Milk, kg/d24.1526.2224.812.0100.58350.2175
3.5% FCM, kg/d27.4228.6927.592.1530.70400.0179
Fat, kg/d1.051.071.040.0830.85080.0028
Fat, %4.334.044.280.1650.42250.6643
Protein, kg/d0.890.910.880.0650.84020.0320
Protein, %3.773.543.570.1050.24100.6877
Lactose, kg/d1.161.261.200.1000.61980.2922
Lactose, %4.774.784.810.0370.66780.1502
Feed efficiency11.241.351.420.1210.33350.036
a,b,cWithin a row, means with different superscripts are different (P <0.05). 13.5% FCM yield (kg/d)/DMI (kg/d).

Key Words: PMR, mixed diet, grazing