Banca de DEFESA: PRISCILA JÚNIA RODRIGUES DA CRUZ

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: PRISCILA JÚNIA RODRIGUES DA CRUZ
DATA: 06/12/2022
HORA: 14:30
LOCAL: Google meet
TÍTULO:

DEFOLIATION INTENSITY OF MARANDU PALISADE GRASS-PINTO PEANUT MIXED PASTURE AFFECTS CANOPY STRUCTURE AND FORAGE INTAKE

PALAVRAS-CHAVES:

Arachis pintoi, nitrogen balance, forage intake, nutritive value, Urochloa brizantha

PÁGINAS: 75
GRANDE ÁREA: Ciências Agrárias
ÁREA: Zootecnia
SUBÁREA: Pastagem e Forragicultura
ESPECIALIDADE: Manejo e Conservação de Pastagens
RESUMO:

Higher mixed canopies tend to reduce the legume proportion due to etiolation of pinto peanut and exposure of growing points to animal removal, leading to a lower stolon density, reducing legume intake. However, it may increase total forage intake. [D.1] This dissertation aims to evaluate the nutritive value of hand-plucking, clipping at stubble height, and extrusa-samples from diets composed by palisadegrass and pinto peanut grazed at three stubble heights; and to determine a defoliation intensity that would favor forage intake with more quality, increasing the apparent efficiency of nitrogen utilization in the animal’s body. The trial was conducted at the Universidade Federal de Lavras, MG, Brazil for two consecutive years. The area was divided into 12 experimental units (paddocks) with three defoliation intensities (severe, moderate and light). The experimental area was constituted by marandu palisade grass (Urochloa brizantha cv. Marandu) and pinto peanut (Arachis pintoi cv. Mandobi). The occupation period of the rotational mob stocking started when the canopy reached 24 to 27 cm and lasted for 9 days. It was used two Tabapua heifers per treatment as testers and put-and-take animals were added when it was necessary to achieve the planned stubble height for each treatment. Canopy characteristics, grazing behavior, short-term intake, and nutritive value were evaluated pre- and postgrazing. Hand-plucking and extrusa were collected during the first and the last day of occupation. The marandu palisade grass and pinto peanut were clipped at 10, 15, and 20 cm in the first occupation day for grazed strata samples. In order to compare the three methodologies, it was calculated the average between the first and the last day of occupation for each botanical component, and after that the nutritive value of the diet was calculated in function of the legume proportion on each paddock. Defoliation intensity (DI), season (S) and the interaction between the two (DI*S) were considered fixed effects, year and replicate were considered random effects. Light defoliation showed greater forage allowance and lower stocking rate than the other intensities (6.3 kg DM/kg LW and 1.3 AU/ha). Grazing time did not differ in the first (390 min; P=0.150) or the last occupation day (440 min; P=0.203). During the last day, 20 cm showed 70% greater intake rate (33.2 g DM/min) than the average of the other treatments, related to greater biting rate (38.0 bites/min) and bite weight (0.9 g DM/bite). Grass and total dry matter intake (DMI; %LW) were greater for moderate and light defoliations, but legume intake was lower for severe and moderate defoliation. The efficiency of microbial synthesis (EMS) was 100 g of microbial protein/kg DOM greater during summer compared to spring but did not vary according to DI (P=795). In order to compare methodologies, defoliation intensity (DI), methodology (M), season (S), and the interaction between the three (DI×M×S) were considered fixed effects, year and replicate were considered random effects. Crude protein concentration (CP) was not affected by any factors or the interaction (P>0.10) and presented an average of 116.7 g/kg of DM. Ash and protein-free neutral detergent fiber (NDF) and organic matter (OM) presented interaction between DI×M×S. Hand-plucking showed greater NDF concentration for all three DI and both S. Extrusa samples showed the lower values of OM regardless the DI and S. The CP, NDF, and OM of diet based on grazed strata were not affected by DI, S, or DI×S (P>0.10). Intake of CP (% LW) was greater for light defoliation based on hand-plucking and was not affected by the other methodologies. Intake of NDF (% LW) was similar for grazed strata and extrusa (1.8% LW) for light defoliation, but for severe, grazed strata presented lower intake than extrusa (1.4 vs. 1.5 % LW). There was no interaction between DI×M×S for intake of CP, NDF, and OM (P>0.10). Stubble height of 15 cm increases SR without reducing DMI. Besides the differences between the methodologies for nutritive value, estimative of intake was not affected by methodology used. 

MEMBROS DA BANCA:
Externo à Instituição - RICARDO ANDRADE REIS - UNESP (Membro)
Interno - MARINA DE ARRUDA CAMARGO DANES (Membro)
Externo à Instituição - JOSÉ CARLOS BATISTA BUBEUX JÚNIOR - UF (Membro)
Interno - ERICK DARLISSON BATISTA (Suplente)
Presidente - DANIEL RUME CASAGRANDE (Membro)
Externo à Instituição - ADENILSON JOSÉ PAIVA - UFRRJ (Suplente)
Externo à Instituição - ABMAEL DA SILVA CARDOSO - UF (Membro)