Changes in the milk response to different herbage mass of dairy cattle in a tropical climate

Iván Calvache1*, Ignacio Beltran2, Oscar Balocchi1, Ruben Pulido3, Luz A. Venegas4, and Alexander Navas4
The interaction between pasture and supplementation in dairy production systems constitutes a very important part of the efficiency of dairy. This study evaluated the effect of the herbage mass (HM) on the milk production and solid concentration. Twenty Holstein cows were distributed into two groups, 10 assigned 2200 kg DM ha-1 (low herbage mass, LHM) and 10 with 2800 kg DM ha-1 (medium herbage mass, MHM). Herbage mass was measured above 5 cm. The experiment lasted 8 wk. The variables evaluated were DM intake (DMI), milk production and composition (fat and protein concentration). Effects of treatments on variables were evaluated using a repeated measure analysis over time. The results showed nonsignificant differences in the pasture DMI between LHM and MHM for weeks 1, 2, 3 and 5 (P> 0.05). During week 4, pasture DMI was 3 kg greater for LHM than MHM (P< 0.05). The milk production did not differ between treatments per week, but the average was 2.4 kg greater for LHM compared to MHM (P < 0.05). In conclusion, changes in the pasture availability increased milk production at LHM, but not enough to cause changes in solids concentration. This clearly shows that, LHM can increase milk and solids production.
Keywords: Intake, milk yield and composition, pasture allowances.
1Universidad Austral de Chile, Facultad de Ciencias Agrarias y Alimentarias, Valdivia 5110566, Chile.
2Instituto de Investigaciones Agropecuarias, INIA Remehue, Osorno 5290000, Chile.
3Universidad Austral de Chile, Facultad de Ciencias Veterinarias, Valdivia 5110566, Chile.
4Universidad de La Salle, Facultad de Ciencias Agropecuarias, Bogotá 110110, Colombia.
*Corresponding author (ivan.calvache@uach.cl).