Meat production on savannah-like grasslands (dehesas) in semi-arid zones of the province of Salamanca [Spain

J.L Martin Polo,I García Bellido,M.E Sánchez Rodríguez

doi:10.5424/sjar/2004021-66

Abstract

Two savannah-like grassland systems (dehesas) in the province of Salamanca (Spain), developed on decomposing slate and granite soils and used for extensive meat production, were examined over a period of three years to determine the stocking rate they could support, their indices of pasture utilization, and the metabolisable energy necessary for meat production. The effective stocking rates were 0.36 and 0.30 cows ha-1 year-1 on the slate and granite systems respectively. The energy provided by supplementary feed was the 34% of the annual nutritional requirements of the herds, but reached more than 60% in the months of greatest need. Pasture utilization was 40% on the slate soil and 38% on the granite soil. The live weight obtained per reproductive cow was between 128 and 217 kg, equivalent to a weight per hectare of 57-90 kg year-1, of which 85% corresponded to calf production. The mean metabolisable energy required for producing one kilogram of meat (live weight) was 361 MJ on the slate soil and 369 MJ on the granite soil (range 215-499 MJ), depending on the year.

Highlights

In a previous paper (Martín Polo et al, 2003), estimations were reported regarding the amounts of available energy and protein in two savannah-like systems – one developed on decomposing slate soil, the other on decomposing granite soil, both typical of stock raising land in the province of Salamanca, Spain
Feed supplementation periods usually last longer than six months, the greater part (80%) of the available feed is pasture
— The current stocking rate (CSR): the result of dividing the total number of maintenance rations over one year required by the herd (MRCT) by the number of maintenance rations per year (i.e., 365) needed by the type animal, and by the available pasture area (APA, ha), identified and estimated from aerial photographs: CSR = MRCT/ (MRC × 365 × APA)

Summary

Introduction

In a previous paper (Martín Polo et al, 2003), estimations were reported regarding the amounts of available energy and protein in two savannah-like systems (dehesas) – one developed on decomposing slate soil, the other on decomposing granite soil, both typical of stock raising land in the province of Salamanca, Spain. The extensive animal production systems of the Extremaduran dehesas (central southwestern Spain) support cattle stocking rates of 0.28 cows ha-1, and an estimated total stocking rate of 0.37 animals ha-1 (Escribano et al, 2001). The present work estimated the current, theoretical and effective stocking rates, pasture utilisation, and meat production per reproductive cow per hectare and year for two dehesa systems of the province of Salamanca, one developed on decomposing slate soil, the other on decomposing granite soil, taking into account the energy requirements and productivity of each. Since data on milk production in Morucha cows were lacking, those for Extremaduran Retinta cows living under similar conditions were used (1,130 kg over seven months of lactation) (Bellido, 1983)

Determination of the stocking rate

Estimation of herd energy needs

Changes in energy needs

MRC MRCT

Animal production