Behavior and reactivity during milking of Holstein, Gyr, and Girolando-F1 cows at the beginning of lactation

Bos indicus cows and their crosses used for milk production are constantly increasing in tropical and subtropical countries, mainly due to their greater adaptability to the climate. However, despite several studies that have reported the greater reactivity of these animals in relation to Bos taurus, there is little information about how Bos indicus cows and their crosses behave in their first lactation and how it affects variables related to production and milking. Thus, we aimed to evaluate the reactivity and milkability of primiparous Holstein, Gyr, and Girolando-F1 (½ Holstein ½ Gyr) cows in the first 21 days of lactation. We used a completely randomized experimental design with repeated measures over time, with 32 cows distributed into three genetic groups. Milk yield, the duration of each milking, and the average and maximum milk flow rates were recorded daily. Variables related to the milking behavior, such as time spent to place the teat cups (min), number of kicks and steps, number of defecation and urination events, and reluctance to be milked score, were evaluated by continuous visual observation at 1, 3, 5, 10, 15, and 20 days in milk (DIM). There was an interaction between genetic groups and days of lactation for milk yield (P < 0.05), where the greatest variations were observed up to the fifth day of lactation, and for time spent for placing the teat cups (P < 0.05), which was 10.2 seconds faster for Holstein cows compared to the other genetic groups at 1 DIM. Also, from 6 to 21 DIM, milking time/kilogram of milk was higher for Gyr cows than for Holstein (P < 0.05), while the differences between Gyr and Girolando-F1 cows varied in the same period. Girolando-F1 cows needed 2.4 more minutes to be milked than Gyr (P < 0.05). The average milk flow rate was higher (P < 0.05) for Holstein cows (1.5 kg/min) compared to Gyr (0.6 kg/min) and Girolando-F1 (0.8 kg/min) cows. The frequency of reluctance score ≥2 was higher (P < 0.05) for Girolando-F1 cows (30.9%) compared with Holstein (8.9%) and Gyr (10%) cows. Stepping increased the probability of Girolando-F1 cows (odds ratio = 1.19; P < 0.01) being classified with a reluctance score ≥2 during milking. Girolando-F1 cows kicked (1.8) and defecated (0.3) more frequently during milking (P < 0.05) compared with Holstein (0.8; 0.0) and Gyr (1.1; 0.1), respectively. In conclusion, reactivity and milkability at the beginning of lactation are distinct for Holstein, Gyr, and Girolando-F1 primiparous cows. Girolando-F1 cows are more reactive at milking, presenting lower milk flow rate and larger milking duration than Holstein cows.