Effect of rotation frequency and stocking rate on herbage quality and animal performance of cow-calf pairs raised on permanent pasture in Quebec

摘要

In Quebec, 62% of agricultural land is devoted to forage production and 20% of this is pasture. Pasture management provides the opportunity for farmers to maintain and improve the productivity of agricultural land, and to engage in sustainable ruminant production. An experiment was conducted on 42 hectares of pasture land to study the impact of management intensive grazing (MIG) on cow-calf productivity. The pasture area was divided into 18 paddocks and the experiment was conducted as a randomized complete block design with two blocks. The treatments were arranged as a 3 x 3 factorial of stocking rate and rotational frequency. The stocking rates (SR) were 0.5, 0.7, and 0.9 hectares per cow (HSR, MSR and LSR respectively); the rotation frequencies (RF) were two days, six days and continuous grazing (2d, 6d and C). Sixty-one purebred Angus cow-calf pairs were randomly assigned to each of the nine treatments, and the animals were grazed during two consecutive grazing seasons (1997 and 1998). Hay harvested early in the season was used for pasture supplementation late in the season. Increasing RF had no effect (P > 0.05) on forage mass available. Increasing SR from 0.9 to 0.5 cow-calf pairs ha -1 resulted in a linear reduction (P < 0.01) in individual cow gain, but increasing the SR caused a linear increase in cow gains ha-1. Calf gain ha-1 increased linearly (P < 0.01) in response to SR, but was unaffected (P > 0.05) by RF. A system of 6d rotation and high SR generated the greatest net revenue. The study showed little benefit of MIG on animal performance, but substantial benefits on efficiency of land use and economic performance.