Ureia microencapsulada de liberação lenta no rúmen de cordeiros em terminação

Abstract

This study aimed to evaluate the best level of including of microencapsulated urea 674 with carnaúba wax for slow release into the rumen, on the performance of lambs in 675 finishing. 50 male sheep (Santa Inês x Dorper), non-castrated, approximately 7 months 676 old and with an average body weight of 31.2 ± 4.8 kg, were distributed in a completely 677 randomized design with five treatments and 10 repetitions per treatment. Five levels of 678 urea inclusion in the diet (g/kg DM) were evaluated, consisting of the control treatment 679 with 4.0 g of free urea, and four treatments of slow-release urea microencapsulated with 680 carnauba wax, at levels of 10.0g, 20.0g, 30.0g and 40.0g based on total dry matter (DM). 681 The experiment lasted a total of 91 days, with 21 days spent adapting to the facilities and 682 diets and 70 days spent evaluating and collecting data. The diets were formulated for an 683 average daily gain of 200g (NRC, 2007) with a 40:60 volume:concentrate ratio. The bulk 684 source used was exhausted mushroom production substrate (SEPC) with the feed supplied 685 as a total mixture. There was no effect of the form of urea supply (free or 686 microencapsulated) or of the increasing inclusions of UMECERA on the consumption of 687 dry matter and other nutrients, or on the variables of the animals' ingestive behavior. The 688 lambs' average daily weight gain showed a plateau between the 10.0g/kg DM and 27.6 689 g/kg DM UMECERA inclusions, followed by a linear reduction. Urea microencapsulated 690 in carnauba wax is efficient in sheep finishing when included at up to 27.5 g/kg of DM, 691 as it allows the animals' average weight gain to be maintained.