The aim of this study was to determine whether increase in proportion of the rumen undegradable starch (RUS) and rumen undegradable protein (RUP) affects the production performance and health status of calves. The experiment was done on 36 Holstein, seven-day-old calves, divided into three groups of 12 calves, with equal sex ratio. The experiment was conducted in two periods. In the first period, calves were fed with full pasteurized milk and milk replacer and additionally fed with starter mixture with different proportions of rumen undegradable protein and starch: Group I 36.6% RUP and 16.5% RUS, Group II 49.1% RUP and 27.6% RUS and Group III 53.5% RUP and 36.5% RUS. In the second period, calves were fed with milk replacer and grower mixture with different proportions of rumen undegradable protein and starch: Group I 33.5% RUP and 15.8% RUS, Group II 48% RUP and 26.3% RUS and Group III 54.3% RUP and 34.6% RUS. In the first period, calves from the Group III had significantly (P<0.01) higher body weight compared to calves in Group I and II (74.75; 59.36; 66.58 kg), as well as daily weight gain (0.76, 0.49, 0.61 kg/d). At the end of the experiment, there was no significant difference in body weight and daily weight gain. The calves in Group I and III had significantly (P<0.05) higher consumption of starter mixture compared to the calves in Group II (7.48; 7.11; 4.33 kg/d), and a significantly (P<0.05) higher overall feed consumption compared to the calves in Group II. The calves in Group II and III had significantly (P<0.05) better feed conversion ratio than the calves in Group I (1.37; 1.50; 2.08 kg/kg). The results of health monitoring (diarrhea, pneumonia) indicate a different proportion of rumen undegradable starch and protein ratio did not have significant effect on calves’ health.
Matija Domaćinović, Josip Juraj Strossmayer University of Osijek, Faculty of Agriculture in Osijek, Vladimira Preloga 1, 31000 Osijek, Croatia, firstname.lastname@example.org