Effect of Urea in Total Mixed Ration and its Silage on Friesian Holstein Bull Calves Productivity in Tropic Condition

Urea addition into feed to some extent has been shown to increase crude protein content and improve feed efficiency. However, its addition in Total Mix Ration (TMR) and also TMR silage on calves’ growth performance is yet to be elaborated. Therefore, the effect urea addition on TMR and its silage on performance of Friesian Holstein (FH) male calves were evaluated. The calves (n = 27; 5 mo to 7 mo, mo = month old) were divided into three groups, each group consisted of nine calves, based on age: 5 mo (100 kg to 105 kg), 6 mo (111 kg to 116 kg), and 7 mo (123 kg to 133 kg). All groups were divided into three types of feed, namely: conventional feed containing concentrate and forage without urea (CON), TMR, and TMR silage containing 1.5 % urea. The variables have been observed were feed intake and digestibility of dry matter (DM) and organic matter (OM) and average daily gain (ADG). The data were analyzed using Analysis of Variance (ANOVA) and followed by Least Significant Difference (LSD) test. The average DM intake (kg head-1 day-1) for CON, TMR, and TMR silages were 5.15; 6.79; and 4.14 meanwhile OM intakes were 4.68; 6.04; and 3.94 respectively, TMR significantly higher than others (P< 0.05). Digestibility of DM and OM (%) showed the same pattern, TMR followed by CON then TMR silage (64.09; 62.98; 54.21 for DMD) and 73.92; 75.99; 63.78 for OMD. The age has non-significant effect into digestibility. Highest ADG (kg head-1 day-1) were was obtained from TMR feed (0.70), followed by CON (0.65) and TMR silages (0.45). The older calves the higher ADG reached (0.65; 0.60 and 0.55). It could be concluded that addition urea 1.5 % in TMR could increase calves’ performances, but on the contrary when it added to TMR silage.