Banca de DEFESA: DÉBORA RIBEIRO GOMIDE

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: DÉBORA RIBEIRO GOMIDE
DATA: 27/10/2022
HORA: 08:00
LOCAL: on-line
TÍTULO:

EFFECT OF PARTICLE SIZE OF GROUND CORN KERNELS REHYDRATED AND ENSILED ON GRAZING DAIRY COWS FED A PARTIAL MIXED RATION

PALAVRAS-CHAVES:

Dairy cows. Feed efficiency. Grazing. Rehydrated corn. Particle size. Starch.

PÁGINAS: 1
GRANDE ÁREA: Ciências Agrárias
ÁREA: Zootecnia
SUBÁREA: Nutrição e Alimentação Animal
ESPECIALIDADE: Avaliação de Alimentos para Animais
RESUMO:

The particle size (PS) of ground corn kernels rehydrated and ensiled (REC) can affect the grinding rate on farm and starch digestibility in dairy cows. We evaluated the effect of PS of REC on dry matter (DM) intake (DMI), lactation performance, total tract digestibility, and ruminal fermentation profile of grazing dairy cows fed a partial mixed ration containing REC ensiled for short duration. Treatments were: coarse REC (CO), fine REC (FI), or finely ground (GC) flint corn (68% vitreousness). Geometrical mean particle size was: 366 µm for GC, 1,364 µm for FI, and 1,694 µm for CO. Cows grazed on Brachiaria brizantha cv. Marandu at 20-day rest and 1-day grazing period, 11.1 ± 1.1 cows/ha, and pasture allowance of 54.8 kg DM/cow^/d. The REC (63.2% DM) was ensiled weekly in plastic buckets (200 L) and stored for 39.9 ± 2.3 days. Eighteen Holstein cows (21.3 ± 4.3 kg milk/d; 563 ± 62 kg body weight; 190 ± 112 days in lactation) received a sequence of the treatments in 6, 3×3 Latin squares, with 21-day periods (with 14-day adaptation). Cows formed 3 groups of 6 cows by production level: High (26.1 ± 2.6 kg/d), Medium (20.9 ± 2.0 kg/d), and Low (16.9 ± 1.0 kg/d). Within each group, 2 squares of 3 cows were formed. A square of 3 rumen-cannulated cows was formed within High. A diet was formulated for each group based on NRC (2001) dairy model predicted DMI and to achieve 1.1% of body weight of intake of forage neutral detergent fiber (NDF). Cows were individually fed a constant amount throughout the experiment of whole-plant corn silage (2.7 kg DM/d), corn treatments, and soybean meal at 0500, 1000, and 1400 h and were milked at 0600 and 1600 h. Fecal excretion and pasture intake were estimated with Cr₂O₃ and undigested NDF at 240 h in situ incubations of feces and feeds. Rumen fluid and blood samples were obtained at 0, 5, and 9 h after morning feeding. Data were analyzed with a model containing the effect of period, group, cow(group), treatment, and the interaction between group and treatment (P ≥ 0.12 for all variables). Blood and rumen data were analyzed as repeated measures. Significance was declared at P ≤ 0.05 and tendency at P ≤ 0.10. Ingredient and nutrient composition of the consumed diets were (% of DM): 39.6 ± 2.7 % pasture, 15.5 ± 1.7 % corn silage, 13.2 ± 1.1 % soybean meal, 29.6 ± 1.4 % corn, 13.5 ± 0.4 % crude protein, 32.2 ± 0.6 % NDF, and 22.6 ± 1.1 % starch. Cows fed FI had lower DMI (16.7 vs. 18.1 kg/d) and digestible organic matter (OM) intake (DOMI; 9.6 vs. 10.6 kg/d) than GC, and both did not differ from CO (17.7 and 9.9 kg/d, respectively). There was no effect of treatment on the yields of milk (19.2 kg/d) and energy corrected milk (ECM; 16.8 kg/d). Milk fat concentration was low (2.99 % of milk) and did not differ by treatment. Cows fed FI had the highest ratios of milk to DMI (1.18 vs. 1.05) and ECM to DOMI (1.86 vs. 1.64). Milk and plasma urea-N and rumen ammonia concentrations did not differ. The lowest total tract digestibility of DM, OM, and starch (86.3 vs. 92.3 % of intake) and the highest fecal starch concentration (7.0 vs. 4.0 % of DM) were detected on cows fed CO. The NDF digestibility was lower on cows fed GC than FI (45.6 vs. 48.9 % of intake). Plasma glucose was higher on cows fed FI and CO (75.0 mg/dL) than on cows fed GC (70.8 mg/dL). Ruminal volatile fatty acids and pH did not differ. Fine grinding of flint corn kernels ensiled for 40 days increased feed efficiency of grazing dairy cows and coarse grinding of REC reduced the total tract starch digestibility.

MEMBROS DA BANCA:
Externo à Instituição - RONALDO FRANCISCO DE LIMA - UFOPA (Membro)
Externo à Instituição - RONALDO BRAGA REIS - UNINCOR (Membro)
Externo à Instituição - RENATA APOCALYPSE NOGUEIRA PEREIRA - EPAMIG (Suplente)
Externo à Instituição - RAYANA BRITO DA SILVA - BN (Suplente)
Externo à Instituição - OZANA DE FÁTIMA ZACARONI - UFG (Membro)
Interno - NADJA GOMES ALVES (Membro)
Presidente - MARCOS NEVES PEREIRA (Membro)