Abstract #W438

Section: Ruminant Nutrition
Session: Ruminant Nutrition: General III
Format: Poster
Day/Time: Wednesday 7:30 AM–9:30 AM
Location: Gatlin Ballroom

# W438
Microbial protein yield of Nellore bulls supplemented with protein sources associated with crude glycerin on finishing phase.
Antonio Jose Neto^*1, Joanis Tilemahos Zervoudakis², Luciana Keiko Hatamoto-Zervoudakis², Luciano da Silva Cabral², Juliane Quenoizoré Soares², Rosemary Lais Galati², Renata Pereira da Silva-Marques², Everton Riva Donida², Lilian Chambó Rondena Pesqueira Silva², ¹Department of Animal Science; São Paulo State University-UNESP, Jaboticabal, SP, Brazil, ²Department of Basic Sciences and Animal Production; Federal University of Mato Grosso-UFMT, Cuiabá, MT, Brazil.

Crude glycerin (Gly) has the potential to partially replace starch-based ingredients in the diet, such as corn, because glycerol is converted to propionate in the rumen and acts as a precursor for hepatic glucose synthesis. The objective of this study was to evaluate the effects of Gly combined with protein sources on microbial protein yield of Nellore bulls fed tropical pasture during the rainy season. Five Nellore bulls (448.2 ± 14 kg; 25 ± 3 mo) were evaluated in a 5 × 5 Latin square design with 5 treatments and 5 periods. The animals were allocated into 5 paddocks of 0.25 ha, consisting of Brachiaria brizantha ‘Marandu’ in the rainy season. Crude glycerin (83.9% of glycerol) was used in all supplements to replace (15% of DM) corn. The supplements were: Gly with urea (GU), Gly with soybean meal (GS), Gly with cottonseed meal (GC), and Gly with corn gluten (GG), and the control received mineral mixture ad libitum. Animals were individually supplemented at the rate of 300 g·100 kg⁻¹ of BW, daily, at 1000 h. Urine samples were collected 4 h after the supplementation to determine the concentration of urea, creatinine, nitrogen and purine derivatives, on the last day of period. Data were analyzed using the PROC MIXED of the SAS. Purines derivatives absorbed, microbial N, microbial protein and CP intake per digestible organic matter intake was lower (P < 0.05) for control compared with protein sources (Table 1). Crude glycerin associated with protein sources can be efficient to improve microbial protein yield. Table 1. Effect of supplemental nitrogen sources associated with crude glycerin on microbial protein yield of Nellore bull in tropical pasture

Item	Supplements					SEM	P-value
Control	GU	GS	GC	GG
Purines derivatives, mmol/d
Allantoin	108.74^b	168.39^a	150.01^a	162.57^a	156.61^a	14.03	0.04
Uric acid	25.40^b	44.14^a	35.34^ab	27.15^b	24.14^b	5.94	0.01
Absorbed	110.13^b	201.99^a	170.54^a	175.93^a	164.69^a	18.02	0.02
Microbial protein yield, g/d	500.44^b	917.83^a	774.94^a	799.45^a	748.36^a	81.88	0.02
CP intake per DOMI¹, g/kg	184.36^b	220.39^a	238.93^a	240.75^a	239.05^a	10.31	<0.01

¹DOMI = digestible organic matter intake.

Key Words: Brachiaria brizantha, glycerin, supplement