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Strategies for increasing the efficiency of nitrogen use in the growing Nellore cattle in pasture

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Verônica Aparecida Costa Mota
Total Authors: 1
Document type: Doctoral Thesis
Press: Jaboticabal. 2019-04-25.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
Defense date:
Advisor: Gustavo Rezende Siqueira

Two experiments were conducted to evaluate nutritional and management strategies to improve the nitrogen efficiency utilization and consequently to increase the performance of supplemented cattle in pasture. The experiments were conducted at APTA - Colina / SP experimental station. The treatments were arranged in a 2 × 2 factorial scheme for the performance and ingestive behavior evaluations in experiment 1 (Exp. 1) and performance in experiment 2 (Exp. 2). Exp. 1 (dry season): two sources of non-protein nitrogen (urea and encapsulated urea [Optigen®] and two supplementation hours [7:00 a.m. and 1:00 p.m.]) and Exp. 2 (rainy season): soybean meal or soybean meal treated [Soypass BR®] with or without plant extract (Cinnagar®). The experiments were carried out in 20 paddocks of Brachiaria brizantha cv. Marandu of 3 hectares with 6 animals each one. The experiment lasted 98 days, 14 days of adaptation, and three periods of 28 days. The animals were weighed with fasting of solids and liquids for 16 hours every 28 days. The Exp. 2 lasted 133 days, 21 days of adaptation and four periods of 28 days. In Exp. 1 the ingestive behavior was: grazing time and daytime trough (6:00 a.m. to 5:50 p.m.), at night (6:00 p.m. to 5:50 a.m.) and total. The instantaneous observations were performed by trained people during 24 hours with frequency interval of 10 minutes, corresponding to a collection of ingestive behavior per experimental period. Ruminal and blood parameters were evaluated in 12 rumen cannulated animals. Four paddocks were used, three simultaneous Latin squares 4 × 4. Each period had a duration of 21 days where, from day 1 to 10, the animals were adapted to the treatments. Blood samples were collected in each period at time zero (before supplementation) and 2, 3 and 6 hours after supplementation. Glucose, protein, urea and creatinine concentrations were measured in the blood. The ruminal fluid was collected on two consecutive days for Exp. 1 where on day 1, liquids were collected at 0, 6, 12 and 18 hours after supplementation and 3, 9, 15 and 21 hours at day 2. Volatilly fatty acid (VFA) and pH analyzes were used only at the time of 0, 6, 12 and 18 hours after supplementation and for ammoniacal nitrogen (N-NH3) at 0, 3, 6, 9, 12, 15 and 21 hours after supplementation. In Exp. 2, ruminal collections were only in one day, at 0, 6, 12 and 18 hours after supplementation. The pH measurements were performed immediately after collection. The average were compared by the t-test and the differences considered from the P < 0.05 and trends were discussed when 0.05 ≥ P ≤ 0.10. In the Exp. 1, there is not interaction among factors for average daily gain (ADG) and body weight (BW). The factors did not influence ADG (P > 0.45) and initial and final body weight (P > 0.39). The ADG was 0.623 kg. Ingestive behavior was influenced only by the experimental periods. The grazing time was reduced in 92 minutes (P < 0.01) in the third period compared to the first and second one. For ruminal parameters, at time 6 after supplementation, ruminal pH values were lower and total VFA greater than supplemented animals at 1:00 p.m. (P < 0.03). There was effect of Optigen® supplementation in isovalerate concentrations and it was possible to observe trends for valerate concentration superiority (P = 0.02 and P = 0.07, respectively). In Exp. 2, there was no influence of factors and their interactions on ADG (P > 0.45) and final body weight (P > 0.22). The ADG for all treatments was 0.921 kg. Animals supplemented with Cinnagar® showed 22% greater urea nitrogen concentration in blood compared to non-supplemented animals (P = 0.03). The highest concentration of glucose of 3.69 mmol/L was observed in the treatments with SoyPass® and presence of essential oil (Cinnagar®), and the soybean meal showed intermediate concentration between the treatments (P < 0.01). Supplementation with NNP sources and different times of dry season supplementation and sources of true protein and essential oil in the waters do not affect Nellore cattle performance in pastures. However, blood and ruminal parameters affect. (AU)

FAPESP's process: 16/05131-4 - Strategies for increasing nitrogen use efficiency in cattle growth phase pastures in Nellore
Grantee:Verônica Aparecida Costa Mota
Support Opportunities: Scholarships in Brazil - Doctorate