Heavy Stocking and Early-Season Deferment of Grazing on Mediterranean-Type Grassland

• Published in: Journal of range management 1999-11, Vol.52 (6), p.590-599
• Main Authors: Gutman, Mario, Zvi Holzer, Hagit Baram, Noy-Meir, Imanuel, No'Am G. Seligman
• Format: Article
• Language: English
• Subjects: Biomass; Calves; Grazing; Grazing management; Growing seasons; Herds; Pastures; Stocking rate; Vegetation; Weaning
• ISSN: 0022-409X
• DOI: 10.2307/4003628

An experiment with beef cows grazing Mediterranean-type grassland was conducted to study the effect of grazing deferment at the beginning of the growing season on pasture productivity and animal performance under intensive herd management conditions. The grazing trial was composed of 4 treatments (deferred grazing at stocking rates of 0.83 and 0.67 cows per ha and continuous grazing at 0.67 and 0.5 cows per ha) replicated in 2 blocks and continued for 5 consecutive years. The herds were given low-energy supplemental feed during deferment and during the dry summer. At the intermediate stocking rate, at which both deferred and continuous grazing were compared, herbage production was significantly reduced by grazing during the 'deferment period' and calf weaning weights without deferment were significantly lower than in the deferred grazing treatments. Weaned live weight per cow was significantly lowest in the continuous intermediate treatment. Weaned weight per hectare was greatest at the highest stocking rate (with deferment). Utilization of supplementary feed per unit weaned live weight was significantly greater in the deferred treatments. Only about a third of the herbage production was grazed, even at the heavy stocking rates. Herbage production varied more between years than between treatments. It is concluded that in the system studied, deferment with supplementary feeding becomes important for both animal and vegetation production as stocking rate approaches and exceeds 0.67 cows ha-1. With deferment, herbage production during the main growing season can be maintained even under heavy grazing pressure. This result can be explained with a simple dynamic growth and grazing model. /// Con el objeto de determinar la influencia del pastoreo deferido, al comienzo del periódo de crecimiento de la vegetacion, en la producción de la pastura y en la perfomance del ganado en condiciones intensivas de manejo, fué realizada una experiencia de pastoreo con ganado vacuno de carne en pasturas naturales de tipo Mediterráneo. Esta experiencia de pastoreo estuvo compuesta por cuatro tratamientos: pastoreo deferido a intensidades de 0.83 y 0.67 vacas por ha. pastoreo continuado a intensidades de 0.67 y 0.50 vacas por ha. La experiencia se condujo durante cinco años, realizada en dos bloques. Durante el período de pastoreo diferido y durante la estación seca fue otorgada alimentación suplementaria compuesta por forrages de bajo contenido energético. En el tratamiento de i