Performance of growing heifers fed urea treated fresh rice straw supplemented with fresh, ensiled or pelleted cassava foliage

Abstract

Abstract Sixty-eight growing heifers were used in three experiments to evaluate the effects on feed intake, growth, liver enzymes and thyroid hormone status of four supplemental levels of cassava foliage: 0 (T0), 50 (T50), 75 (T75) and 100 g (T100) crude protein 100 kg− 1 LWt provided by fresh, ensiled or pelleted cassava foliage in diets based on urea treated fresh rice straw (UFRS) ad libitum, 0.72 kg dry matter (DM) of napier grass and 0.26 kg DM of cassava root meal (CRM) 100 kg− 1 LWt. The ensiled cassava foliage (ECF) supplement experiment was conducted from June to October in 2002, and the fresh (FCF) and pelleted (PCF) cassava foliage supplement experiments from February to June and August to December in 2003, respectively. The results showed that increasing the level of cassava foliage supplementation in the all experiments slightly decreased UFRS intake (p 0.05) in the PCF and ECF supplement experiments. It is concluded that FCF with its high HCN and condensed tannin content was slightly unpalatable, had a negative effect on circulating thyroid hormones at higher supplemental levels and an adverse effect on growth rate, while ECF and PCF supplementation resulted in improved growth rate without adverse effect on thyroid hormones and feed intake when fed to growing heifers.