Influência da suplementação com proteína não-degradável no rúmen sobre o consumo, metabolismo e desempenho na recria de bovinos Nelore em pasto
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Data
2020-02-17
Autores
Camargo, Karine Dalla Vecchia
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste estudo foi avaliar a influência da suplementação ou não com proteína não degradável no rúmen (PNDR) sobre o consumo, metabolismo e desempenho de bovinos Nelore na fase da recria, durante o período das águas. Os animais foram mantidos em pastagem de Urochloa brizantha cv. Xaraés (PB = 12,3%), sob pastejo contínuo e método put and take. Dois experimentos foram realizados simultaneamente e as seguintes suplementações foram avaliadas: suplementação mineral (SM), suplementação proteica de 3 g/kg PC de glúten de milho 60 (GLU) ou farelo de soja protegido (FSP). As médias dos tratamentos foram comparadas utilizando contrastes ortogonais (SM vs. PNDR; e GLU vs. FSP). O experimento de desempenho (Exp1) teve duração de 112 dias, utilizou-se 96 tourinhos jovens da raça Nelore com peso corporal inicial médio de 240 ± 19,72 kg, distribuídos em um delineamento em blocos ao acaso. A suplementação com PNDR promoveu aumento no ganho médio diário (GMD; P <0,01), com ganho adicional de 205 g/dia para GLU e FSP em relação ao SM, sem diferenças entre as fontes de proteicas suplementadas. O experimento de metabolismo (Exp2) teve duração de 84 dias e foram utilizados 9 novilhos da raça Nelore, castrados, canulados no rúmen e duodeno, com aproximadamente 350 ± 78,51 kg de peso corporal inicial. Os animais foram distribuídos em 3 quadrados latinos simultâneos 3 x 3. Não foram observadas alterações no consumo de matéria seca (CMS kg e %PC), consumo de matéria orgânica e de forragem (P ≥ 0,11). A suplementação com GLU e FSP aumentou o consumo de proteína bruta (PB), consumo de nitrogênio (N) e de energia metabolizável (P <0,01), além de aumentar a digestibilidade aparente total da proteína bruta (P = 0,08). A concentração de nitrogênio amoniacal ruminal (NAR) aumentou com a suplementação proteica (P <0,01), mas esta suplementação não alterou o pH e a concentração total de ácidos graxos de cadeia curta (AGCC; P ≥ 0,34). Animais suplementados com FSP apresentaram maior produção de AGCC (P <0,01) e uma tendência a maior concentração de NAR (P = 0,07) em comparação com o GLU. Houve interação entre os tratamentos e o tempo de amostragem na produção do ácido isovalérico (P = 0,02), com o GLU apresentando maior concentração desse ácido, 6 horas após a suplementação. A produção dos ácidos isobutírico e isovalérico foi maior para GLU e FSP em comparação ao SM (P <0,01), e uma tendência de comportamento similar foi observada para o ácido valérico (P = 0,08). A excreção de N na urina e nas fezes foi menor para FSP do que para GLU (P= 0,04). Além disso, a retenção de N em % do consumo de N tendeu a aumentar com a suplementação proteica (P = 0,08) e foi maior para FSP em comparação ao GLU (P <0,01). Em conclusão, a suplementação com PNDR aumentou o desempenho animal e o status de nitrogênio para o metabolismo animal, sendo que FSP resultou em maior eficiência de utilização do nitrogênio.
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.
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.
Descrição
Palavras-chave
Proteína metabolizável, Aminoácidos, Retenção de nitrogênio, Bovinos de corte, Metabolizable protein, Amino acids, Nitrogen retention, Beef cattle