Effect of ruminal undegradable protein supplementation on intake, metabolism, and performance in beef cattle grazing pasture on the growing phase

Author(s)

Karine Dalla Vecchia Camargo

• Document type: Master's Dissertation
• Press: Jaboticabal. 2020-07-02.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2020-02-17
• Advisor: Telma Teresinha Berchielli; Juliana Duarte Messana; Yury Tatiana Granja Salcedo

Abstract

The aim of this study was to evaluate the effect of ruminal undegradable protein (RUP) supplementation on intake, metabolism and, performance of Nellore cattle on the growing phase, during the rainy season. The animals were kept on pasture of Urochloa brizantha cv. Xaraes (CP = 12.3%), in continuous grazing, and put and take method. Two experiments were carried out simultaneously, and the supplements evaluated were: mineral supplementation (MS), protein supplementation of 3 g/ kg BW of corn gluten 60 (CG) or protected soybean meal (PSM). The treatment means were compared using orthogonal contrasts (MS vs. RUP; and CG vs. PSM). The performance experiment (Exp1) lasted 112 days, using 96 young Nellore bulls with average initial body weight of 240 ± 19.72 kg, assigned in a randomized block design. RUP supplementation promoted an increase in average daily gain (ADG; P <0.01), with an additional gain of 205g/ day for CG and PSM compared to MS, with no differences between supplemented protein sources. The metabolism experiment (Exp2) lasted 84 days and 9 Nellore steers, castrated, cannulated in the rumen and duodenum, with approximately 350 ± 78.51 kg initial body weight were used. The animals were assigned in 3 simultaneous 3 x 3 Latin squares. There were no changes in dry matter intake (DMI kg, and % BW), organic matter intake, and forage intake (P ≥ 0.11). Supplementation with CG, and PSM increased the crude protein (CP), nitrogen (N), metabolizable energy intake (P <0.01), and increased the total apparent digestibility of the crude protein (P = 0.08). The ruminal ammoniacal nitrogen (RAN) concentration increased with protein supplementation (P <0.01), but this supplementation did not change the pH and the total short-chain fatty acids (SCFA) concentration (P ≥ 0.34). Animals supplemented with PSM showed higher SCFA production (P <0.01), and a tendency to higher concentration of RAN (P = 0.07) compared to CG. There was interaction among the treatments and the sampling time to isovaleric acid (P = 0.02), where the CG showed higher concentration of this acid 6 hours after supplementation. The production of isobutyric, and isovaleric acids was higher for CG and PSM compared to MS (P <0.01), and a similar behavior trend was observed for valeric acid (P = 0.08). The excretion of N in urine and faeces was lower for PSM than for CG (P = 0.04). In addition, N retention in % of N intake tended to increase with protein supplementation (P = 0.08) and was greater for PSM compared to CG (P <0.01). In conclusion, supplementation with RUP increased animal performance and nitrogen status for animal metabolism, with PSM resulting in greater nitrogen utilization efficiency. (AU)

• FAPESP's process: 18/06836-7 - Influence of rumen non-degradable protein supplementation on intake, metabolism and performance in Nelore cattle grazing on pasture
• Grantee: Karine Dalla Vecchia Camargo
• Support Opportunities: Scholarships in Brazil - Master