Abstract The present study was planned to test the hypothesis that feeding lactating dairy cattle with varying levels of rumen-undegradable protein (RUP) can enhance protein utilization, milk production, milk protein, and nitrogen (N) excretion. Forty mid-lactating crossbred (Jersey × Friesian) cattle were randomly divided into four groups. Four treatment diets were formulated to contain 30%, 40%, 50%, and 60% RUP of crude protein. Dry matter (DM) and crude protein intakes were significantly reduced with increasing dietary RUP levels. Crude protein digestibility increased linearly with incremental increases in dietary RUP levels. Cattle fed 60% RUP showed a linear decrease in N intake compared to that in the other groups. A linear decrease in urinary N and linear increases in net N, milk N, and N-use efficiency were observed with increasing dietary RUP levels. Actual milk, energy-corrected milk, and 4% fat-corrected milk yields (kg/day) increased linearly with an increasing degradability of protein. However, milk protein, solids not fat and total solids, as well as the yields of protein, fat, and lactose, showed significant increases with increased RUP supplementation. Collectively, the results indicate that formulating dairy cow diets to contain 60% RUP results in better lactating performance and N-use efficiency and lower N excretion.

ABSTRACT The objective of this study was to evaluate the effect of source of roughage and crude protein level on feeding performance and carcass traits of Majaheem camels (Camelus dromedarius). Forty-eight male calf-camels weighing 203.3±5.1 kg were equally assigned to a 2 × 3 factorial arrangement of two sources of roughage (Rhodes grass hay and dry salicornia biomass) and three dietary crude protein levels (12, 14.5, and 17%); the feeding trial lasted for 18 weeks. The results showed that slaughter and hot carcass weights, average daily gain, dry matter intake, feed efficiency, and separable fat from 9th-11th rib joint increased as the crude protein in the diets increased from 12 to 14.5%, whereas increasing crude protein to 17% resulted in no further changes. Slaughter weight, average daily gain, hot carcass weight, rib eye area, and separable lean did not differ between Rhodes grass and salicornia diets, but salicornia-fed camels had higher dry matter intake and produced heavier kidney fat and separable fat weights than camels fed Rhodes grass diets. It is suggested that the inclusion of salicornia biomass as a roughage ingredient up to 25% in the diet containing not greater than 14.5% crude protein can be utilized without adverse effect on feeding performance of calf-camels.