ABSTRACT
Time of supplementing grazing dairy cows with pasture silage during summer.

Oscar Strauch B.1, Antonio Hargreaves B., Francisco Lanuza A. y Carlos Uribe
 

A study aiming to determinate the most appropriate time of silage supplementing in lactating milking cows was conducted atthe Remehue Research Center belongingto the National Institute of Agricultural Research, located in Osomo, Chile. The experiment lasted 80 days. Twentyfour spring calving dairy cows selected from the herd kept at the Centre were used. Taking into account their previous lactation production they were allocated into the following treatments within a randomised block design: SP: only grazing; AO: grazing plus silage supplementing before milking; and DO: grazing plus silage supplementing after milking. Grass silage (2.44 Mcal kg-1 DM-1) was offered ad libilum during 45 min before and after each milking, respectively. Average grass intake (kgDMday-1) was: 15.7a; 13.3b and 13.2b fortreatments SP, AO and DO, respectively (P< 0.01). Silage intake (kg DM day-1) was significantiy different (P < 0.01) among treatments AO and DO with 3.44a and 3.09b values, respectively. Milk production for control treatments (16.1 L day-1) was significantiy different (P <0.05) from supplemented treatments: AO: 18 and DO: 17.8Lday-1 respectively. Therewas a trend for longer grazing times in AO when compared with DO, although not statistically significant differences were detected. Ruminating time was longer in AO than in DO and SP treatments (P< 0.01). Milk constituents were not significantiy affected by treatments. It can be concluded that a higher efficiency of utilisation and longer grazing time is achieved when supplementing is offered before milking. Nevertheless, significant productive differences between different times of silage supplementing were not observed in this trial.

Keywords: dairy cows, milk production, silage consumption.
1 Instituto de Investigaciones Agropecuarias, INIA-Kampenaike, Casilla 277, Punta Arenas, Chile. E-mail: ostrauch@inia.cl.