Productive parameters, metabolic and economic viability of dairy cows supplemented with different levels of urea in diets based on sugar cane

Abstract Text: Sugarcane has been recommended for dairy farms that utilize low-yielding cows, used in to feeding regimes that do not seek to obtain high lactating performance per animal. The utilization of sugarcane and other feedstuffs, should be based on dietary formulations that incorporate nutritional-model recommendations of practical use (NRC, 2001). Sugarcane was also considered adequate for dairy cattle producing 20 kg of milk per day. The sugarcane yield support potential, in balanced diets, must be defined more precisely to allow recommendations to be specifically targeted. No scientific data exist to support the use of sugarcane in diets formulated for high-performance lactating animals. Sugarcane has been used for animals of higher production due to its qualities, among them, the low cost of dry matter. However, the appropriate level of urea in to add to cane sugar diets  feed to high production animal is still questionable. The objective of this study was to evaluate feed intake, nutrient digestibility, feed efficiency, production and milk composition, metabolic parameters and the economic viability of lactating cows fed diets based on sugar cane supplemented with increasing levels of urea: sulfate on dry matter basis (0, 0.5 and 1.0%). Twelve multiparous cows and six primiparous Holstein and Holstein x Gir, with 83 + 7 days of lactation, average milk yield of 21.3 ± 0.8 kg / day, average body weight of 580 + 18.3 kg, fed with total mixed ration 50:50, assigned to reversion assay type switch-back, 3 x 3. Cows fed the diet with 1.0 % urea had lower (P<0.05) dry matter intake (DMI) and organic matter intake (OMI), but feed efficiency higher on this diet. DMI, OMI and feed efficiency was 19.64, 19.66 and 18.33 kg/d, 18.24, 18.31 and 17.03 kg/d and 1.14, 1.17 and 1.71 kg/kg, respectively for diets containing 0.0%, 0.5% and 1.0% of urea. There was no effect of diet on nutrient digestibility, milk yield, milk composition and on plasma concentration of urea, glucose and insulin (P>0.05). All diets had a positive balance if considered only cost with food, however the 1% urea diet showed the best outcome per cow. For dairy cows, with an average milk yield of 22 kg/day, sugar cane supplemented with 1% urea in green matter basis despite decreasing the dry matter intake, may be used, without causing any adverse effect on production and metabolic and improve parameters of cost.

Keywords: sugar cane, urea , productive parameters.