Comportamento ingestivo e taxa de passagem de partículas em novilhas leiteiras de diferentes grupos genéticos submetidas a dietas com diferentes níveis de fibra
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Data
2007-07-09
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Revista Brasileira de Zootecnia
Resumo
O trabalho foi conduzido para avaliar a taxa de passagem de partículas do volumoso e o comportamento ingestivo de novilhas leiteiras de três grupos genéticos Holandes (H) x Zebu (Z): 7/8HZ, 15/16 HZ e Holandês Puro por Cruza (HPC), mantidas em confinamento e alimentadas com dietas, em mistura completa, com dois níveis (30 e 60%) de fibra em detergente neutro (FDN), utilizando-se como volumoso o capim-elefante (Pennisetum purpureum, Schum., cv. Mineirão) picado. O experimento foi conduzido em esquema fatorial 3 × 2 (grupo genético × nível de fibra), em delineamento em blocos casualizados, com quatro repetições. O ensaio para determinação da taxa de passagem foi conduzido no final do período experimental, em delineamento inteiramente casualizado com três repetições. O tempo de retenção no rúmen-retículo (TRRR) foi 13,8% menor e o tempo de retenção no ceco-cólon (TRCC), 13,9% maior para a dieta com 30% de FDN em relação à dieta com 60% de FDN. Para o nível de 60% de FDN na dieta, houve maior tempo gasto com alimentação, ruminação e mastigação total, enquanto a taxa de ingestão e a taxa de ruminação da MS foram menores. Quanto aos grupos genéticos, o TRRR foi 14,75% maior para as novilhas 7/8HZ em relação às novilhas HPC e o TRCC foi 28,2% menor para as novilhas 7/8HZ. As novilhas HPC gastaram mais tempo em atividades de alimentação e mastigação, porém, com menores taxas de ingestão que novilhas 7/8HZ.
This work was carried out to evaluate the forage particle passage rates and ingestive behavior of dairy heifers from three genetic groups Holstein (H) and Zebu (Z) cattle (7/8HZ, 15/16HZ, Graded Holstein - GH), kept in feedlot regime and submitted to diets, in a total mixed ration, with two fiber levels (30 and 60%) of neutral detergent fiber (NDF), using chopped Elephant grass (Pennisetum purpureum, Schum., cv. Mineirão) as forage. The experiment was conducted in a 3 × 2 factorial arrangement (genetic group × fiber level), in a completely randomized design, with four replicates. The digestive kinetic trial was determined in the end of the experimental period in a completely randomized design with three replicates. Rumen-reticulum retention time (RRRT) was 13.8% lower and cecum-colon retention time (CCRT) was 13.9% higher for the diet with 30% NDF in relation to the diet with 60% NDF. There was a higher spending time with feeding, rumination and total chew, while the ingestive rate and rumination rate of DM were lower for the 60% NDF level in the diet. As for genetic groups, RRRT was 14.75% higher for the 7/8HZ heifers than for GH, and CCRT was 28.2% lower for 7/8HZ heifers. Graded Holstein heifers spent more time in activities of feeding and chewing, however, with lower intake rate than 7/8HZ heifers.
This work was carried out to evaluate the forage particle passage rates and ingestive behavior of dairy heifers from three genetic groups Holstein (H) and Zebu (Z) cattle (7/8HZ, 15/16HZ, Graded Holstein - GH), kept in feedlot regime and submitted to diets, in a total mixed ration, with two fiber levels (30 and 60%) of neutral detergent fiber (NDF), using chopped Elephant grass (Pennisetum purpureum, Schum., cv. Mineirão) as forage. The experiment was conducted in a 3 × 2 factorial arrangement (genetic group × fiber level), in a completely randomized design, with four replicates. The digestive kinetic trial was determined in the end of the experimental period in a completely randomized design with three replicates. Rumen-reticulum retention time (RRRT) was 13.8% lower and cecum-colon retention time (CCRT) was 13.9% higher for the diet with 30% NDF in relation to the diet with 60% NDF. There was a higher spending time with feeding, rumination and total chew, while the ingestive rate and rumination rate of DM were lower for the 60% NDF level in the diet. As for genetic groups, RRRT was 14.75% higher for the 7/8HZ heifers than for GH, and CCRT was 28.2% lower for 7/8HZ heifers. Graded Holstein heifers spent more time in activities of feeding and chewing, however, with lower intake rate than 7/8HZ heifers.
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Palavras-chave
Capim-elefante, Cinética ruminal, Mastigação merícica, Tempo de mastigação