Behaviour of young dairy bulls under group housing conditions and mature dairy bulls during semen collection

Abstract: The first aim was to observe the behaviour of young dairy bulls under group housing conditions and difference in the aggressive and other social interactions between the bulls.Behaviour of 163 bulls of Swedish Holstein (SH) and Swedish Red and White Breed (SRB), from 1.5 to 4 years, was observed. The bulls were housed in groups of 7-12/pen in 16 different pens in two half open buildings. The bulls were divided into three age groups (2, 3 and 4 year). Statistical analysis was done to test the difference of age, breed and observer on the general behaviours, and the effect of age, breed and breed'age on the social interactions. A significantly higher percentage of lying in the 2 year age groups, ruminating standing in the 3 year age groups and rubbing walls in the 4 year age groups was found. Aggressive behaviour was the major social interaction among the bulls of all age groups. Mounting was significantly higher for the 2 year age groups and lower in 4 year age groups. It was concluded that the bulls living under group housing conditions spent most of their time standing, eating and lying ruminating (during our observation period). The bulls showed a quite high level of aggressive behaviours, but that did not seem to cause harm to their health. There were no differences in the aggressive behaviours between breeds and age groups.The second purpose was to observe the behaviour and the reaction time (RT) of mature dairy bulls during semen collection and the effect of handling staff (3 persons at a time) and other factors during semen collection. Effect of delayed RT on semen quantity, semen quality and total sperm collected (TSC) per ejaculate was also investigated. Behaviour of 18 bulls (13 SRB and 5 SH) was recoded. The bulls were divided into four age groups (5, 6, 7 and 8 year). Statistical analysis was done to investigate the effect of day (once or twice a week), order (of the bulls 1-9, during semen collection), age group, handler A, B and collector (seven people handling bulls on different days) on RT, behaviours, semen quantity, semen quality and TSC. The RT to first mount, first semen collection and second semen collection was 253.84 s, 91.08 s and 110.02 s respectively. A significant effect of handler B and day on RT to first ejaculation was found. Walking, sniff teaser and vocalize tended to be affected by handler A. A significant negative correlation between RT and semen quality, RT and TSC in the first semen ejaculates was found. A higher number of sperms per ejaculate were collected from the bulls being collected once a week. It was concluded that RT and some behaviours of the bulls was affected by the presence of different handling persons in the semen collection hall. Moreover long RT caused a decreased TSC with low quality.