Correlation between intake and ingestive behavior of pasture-grazed heifers

Abstract

The objective of this study was to evaluate the correlation between intake and ingestive behavior of crossbred heifers in grazing tropical. The experiment was conducted on the Princesa do Mateiro Farm, in the city of Ribeirão do Largo, Bahia. A total of 20 heifers with genetic makeup 5/8 dairy Guzerá and 3/8 Holstein, average age of 18 months and body weight of 187 ± 13.1 kg have been used. The experiment lasted 224 days and involved animals raised in a rotational grazing system with Brachiaria brizantha cv. Marandú. Grazing time was not correlated with any of the variables associated with intake. Rumination time showed positive correlations with the intake of forage dry matter (DMIF) and neutral detergent fiber (NDFI). Variables associated with the time spent on feeding at the trough, overall feeding and total chewing were not correlated with intake (P>0.05). There have been positive correlations between the number of grazing periods (NGP) and rumination periods (NRP) and total DM intake (TDMI), organic matter (OMI), forage (DMIF), neutral detergent fiber (NDFI), total carbohydrates (TCHI) and ether extract (EEI). Crude protein intake (CPI) was positively correlated with NGP and NRP. The mouthful rate was positively correlated with TDMI, OMI, DMIF, NDFI, TCHI, EEI and CPI. Average time per swallow was negatively correlated with TDMI, OMI, NDFI, TCHI and EEI. Positive correlations have been observed between the number of mouthfuls per day and TDMI, OMI, DMIF, NDFI, TCHI, EEI. The number of chews per bolus showed negative correlations with DMIS and CPI. The time per cake ruminated has correlated negatively with the intake of crude protein. The number of chews per bolus showed positive correlations with the intakes of dry matter and neutral detergent fiber. The number of boli per day showed positive correlations with DMIF and TCHI. The time spent on chewing showed no significant correlation with intake. In conflict with the national and international literature, the grazing time was not correlated with intake by grass-fed crossbred heifers. The number of activities, the time spent on them and the mouthful rate where shown to be highly associated with the intake variables and can therefore arrange equations to predict intake through the analysis of feeding behavior. The number of mouthfuls performed each day contributes to the intake by pasture-grazed heifers.