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Impact of dry ground corn particle size on production performance of dairy cows.

R. Almeida

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06-23-2020

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Abstract:

T127
Impact of dry ground corn particle size on production performance of dairy cows.
I. F. Carrari1, M. Poczynek1, A. M. Fillus1, C. B. da Silva2, F. S. Baptista3, L. B. Los3, L. F. Ferraretto4, R. Almeida*1. 1Universidade Federal do Paran� Curitiba, PR, Brazil, 2Universidade Federal de Lavras Lavras, MG, Brazil, 3Fr�sia Cooperativa Agroindustrial Carambe�, PR, Brazil, 4University of Florida Gainesville, FL.

The objective of this trial was to evaluate the impact of dry ground corn mean particle size on production performance of lactating cows. Fifty Holstein dairy cows were separated in 2 groups receiving diets with either coarsely (915 �m) or finely (660 �m) ground corn. Cows were housed in individual tie-stalls in the same barn, equipped with wooden side panels. The ground corn inclusion in the experimental diet was modest; only 3.1 kg DM/d or 14.5% of total diet DM, and the estimated total dietary starch was 26.1%DM, in both treatments. The experimental design was a randomized block design, using parity, milk yield, and DIM data from pre-experimental period as blocking factors. Statistical analyses were performed using the GLM for single measures and MIXED procedure of SAS for repeated measures over time. The results indicate that cows fed finely ground corn diet had lower (P < 0.01) fecal starch than cows fed coarsely ground corn diet (4.84 vs. 6.96%; SEM = 0.26), as well as greater (P < 0.01) total-tract starch digestibility (93.95 vs. 91.29%; SEM = 0.32). Individual dry matter intake was also lower (P < 0.01) for cows fed finely ground corn diet (21.22 vs. 22.05 kg; SEM = 0.20). Milk yield tended to be greater for cows fed finely ground corn diet (37.90 vs. 36.85 kg; SEM = 0.45; P = 0.12), as well as greater actual milk feed efficiency (1.78 vs. 1.69 L/kg; SEM = 0.04; P = 0.15), than for cows fed coarsely ground corn diet. However, milk fat (3.63 vs. 3.73%; SEM = 0.07; P = 0.29) and milk total protein (3.31 vs. 3.34%; SEM = 0.03; P = 0.52) contents, respectively for finely and coarsely ground corn diets, were not affected by treatment, as well as lactose, casein and total solids contents. Plasma d-lactate concentration was greater (P = 0.04) for cows fed finely ground corn diet (98.5 vs. 79.7 �M; SEM = 6.10). In conclusion, the adoption of smaller dry ground corn mean particle size improves starch availability and decreases fecal starch, improving total-tract starch digestibility. Furthermore, reducing dry ground corn particle size decreased DMI and improved milk production efficiency.

Keywords: dry matter intake, milk yield, starch digestibilty.