Comportamento ingestivo de novilhos de corte em diferentes alturas da pastagem de Urochloa ruziziensis

Abstract

The study of the ingestive behavior of cattle is conducted to evaluate the relationship of the animal with the system it is inserted into, assisting in improvements in management practices, reducing unfavorable conditions for its feeding, and thus meeting its requirements, whether for maintenance or production. This work aimed to evaluate the animal and ingestive behavior of beef heifers on Urochloa ruziziensis pasture managed at different grazing heights. The experiment was conducted at the Teaching and Research Center in Ruminants (NEPRu), located at the Federal Technological University of Paraná (UTFPR) Dois Vizinhos Campus PR, from January to June 2024. The experimental design was a completely randomized block design, with three repetitions (paddocks) and three pasture management heights (treatments). The evaluated heights were: low. The experimental design was a randomized block with three replications (paddocks) and three pasture management heights (treatments). The evaluated heights were: low at 30 cm (BA), medium at 37 cm (ME), and high at 50 cm (AA). The experimental area was 6.03 ha, divided into 9 paddocks of equal size. A total of 27 Purunã breed steers were used, with an average initial weight of 290 kg, employing continuous grazing. Data collection was conducted in April, with evaluations carried out over two consecutive days, lasting 12 hours each day (6:30 AM 6:30 PM). The increase in pasture height raised (P<0.05) the forage mass. The proportions of leaf, inflorescence, stem, and dead material did not differ (P>0.05) due to the different heights of forage management. The crude protein (CP) levels were lower (P<0.05) for AA compared to the other heights of management, while the levels of NDF and ADF increased. The time spent grazing was greater (P<0.05) in treatment AA and did not differ in the others. The time in idleness was higher (P<0.05) in treatment BA, given that the animals spent more time performing grazing activities in treatment AA. There was no difference (P<0.05) between the treatments in rumination time, even with different fiber levels between the treatments. The time per bolus per minute (TBO) was higher in treatments AA and BA. The number of chews per minute (NM/min) and the number of daily chews (NMD) were lower in treatments AA and BA. The height of management did not alter the number of steps in 10 feeding stations (NP10E) and the number of stations/minute (NE/min). There was no difference (P<0.05) in T20B (time of 20 bites) and NB/min (number of bites per minute). The pasture of Urochloa ruziziensis, managed between heights of 30 and 37 cm, resulted in a shorter grazing time and longer resting time, without altering rumination. At a height of 37 cm, the animals increased the number of chews per bolus of feed.