Self-feeding improved animal performance of calves grazing native grasslands during winter on extensive livestock production systems

Abstract

Supplementing calves on deferred native grasslands during their first winter, helps overcoming the nutritive deficits which occur during this season. However, the demand of both qualification and availability of labour may restrain its adoption. The objective of this work was to evaluate calves’ average daily live weight gain (ADG) and supplemental feed efficiency (SFE) as a response to self-feeding methods. Two experiments (Exp) were carried out: i) Exp A, on sandy soils with Braford calves and, ii) Exp B on basaltic soils with Hereford calves. In each experiment 40 castrated male calves were used and randomly allotted to one of two replicates of these treatments: non-supplemented control (C); everyday restricted supplementation (E); restricted self-fed supplementation delivered two times a week (RSF); ad libitum self-fed (ASF). Exp A registered lowest ADG for C (0.155 kg an-1 day-1), similar ADG between E and RSF (0.623 kg an-1 day-1 on average) and highest for ASF (1.135 kg an-1 day-1) (p <0.05). For Exp B, ADG was affected being C ≤ E ≤ RSF < ASF (0.158, 0.390, 0.588 and 1.319 kg an-1 day-1, respectively). SFE values were not different (p >0.05) between treatments for Exp A, even though ASF presented a 50% higher SFE (9.4) than RSF (6.2) and E (6.1). SFE was affected (p <0.05), being ASF (7.7) < E = RSF (3.9 on average). It is possible to overcome winter live weight losses through the combination of deferred native grasslands and restricted self-feeding.