Grazing Behavior, Rumination Patterns, and Pasture Performance Indicators

This deposit contains a set of photographs showing the dairy cow breeds included in the study. These images are supplemental material for a manuscript submitted to the Journal of Dairy Science.

Here is the abstract of the article: This study investigated the effects of breed composition and sire breed on the diurnal grazing and rumination behavior of dairy cows in a pasture-based system. Thirteen cows, including Holstein (HO), GrazeCross crossbreds (GC; Jersey × Normande × Viking Red), and ProCross crossbreds (PC; Holstein × Montbéliarde × Viking Red), were fitted with RumiWatch collars to monitor their daily activities over a period of 7 days in the summer of 2021. Cows consumed 100% of DMI from perennial cool-season grass pasture. Total daily and hourly grazing, rumination, and other behaviors were evaluated with mixed models that considered the date, breed composition (either sire breed or breed group), and random cow effects. Additional performance traits, including BCS, fly infestation, surface body temperature, milk and component yield, and fecal samples to facilitate feed digestibility measurements, were collected from a total of 31 herd mates. Grazing activity peaked at 07:00 through the rest of the morning and again from 20:00 to 22:00, whereas rumination peaked at 23:00 and remained elevated overnight, following a consistent diurnal rhythm regardless of breed composition. The GC cows grazed longer (574.1 min/d) than PC (501.5 min/d) and HO cows (548.9 min/d), although total rumination time was similar across groups. The HO-sired cows tended to have lower BCS and had higher fly scores than the other breeds but didn’t show differences for thermal images and pdNDF. More time grazing was associated with a general increase in milk, fat, and protein yields in a multivariate analysis of variance. These findings highlight that grazing behavior followed a similar pattern across breeds and demonstrate the potential of novel pasture performance indicators, including feed digestibility measures from fecal samples, thermal imaging, and fly scoring, to evaluate breed-specific efficiency in grazing systems. Key Words: Dairy cows, grazing behavior, rumination, crossbreeding, feed efficiency