Growth of Merino weaners fed grain-based diets while grazing dry pasture or housed in feedlots

Abstract

The growth of Merino wether weaners fed, ad lib., 2 types of oat grain or an oat-lupin mix were compared under 3 management systems: while grazing pasture (GP), in an outdoor feedlot (OF), or in an indoor feedlot (IF). Significant interactions between management system and diet persisted until day 132 of feeding, with weaners on all diets performing better with GP than with OF and IF treatments during early stages of the experiment. The superiority of the GP treatments was mainly associated with very low rates of growth, or liveweight loss, of the sheep in OF and IF treatments in the first 34 days of feeding (180-201 g/sheep.day compared with -51-47 and - 39-127 g/sheep.day respectively). Diet modified the influence of management system, with the better quality diet (oat-lupin mix) appearing to assist in adaptation to the feedlot environment. The effect of diet remained significant (P> 0.01) throughout the experiment. Over the entire experiment (7 Dec. 1979-18 Sept. 1980), the liveweights achieved and feed consumption of the weaners in the feedlots were similar to those for weaners feeding from a self-feeder while grazing pasture. In the longer term, choice of a management system (paddock or feedlot) may not be important to weaner growth, as early setbacks experienced due to adaptation to the intensive feedlot environment were later compensated for by faster growth.