عنوان مقاله [English]
Introduction: In most dairy farms, calves are housed individually during the milk-feeding period and will only introduce to social groups after weaning. Individual housing can help keep calves healthy by reducing disease transmission and incidence behavioral problems such as cross-sucking as well as providing individual feeding and health-care of the calf. Nevertheless, individual rearing systems through lack of social contact can compromise the welfare of the calf. Calves are social animals, thus keeping calves in groups can promote more normal social behavior. Also, social housing results in decreased labor costs associated with calf rearing, increased solid feed intake, weight gains, and less fear of novel social situations. Despite all the performance and behavioral advantages in calves with social housing compared to individually housing, there are concerns about the close relationship between calves and the risk of disease transmission. It has been reported a higher frequency of diarrhea in socially housed calves compared with individually housed calves at week 3. Thereby the risk of morbidity and mortality can be reduced if calves are grouped after 3 weeks of age onwards. Also, no considerable differences were observed for social behaviors between calves housed together from birth compared with those housed together from 3 week of life. Research is needed to establish best practices to rear the calves whilst improving the welfare, health, and growth of dairy calves. Therefore the aim of this experiment was to investigate the effect of individual or group housing (from 4 weeks) on performance, blood parameters, ruminal fermentation, behavior, and health of dairy calves.
Materials and Methods: A total of 32 Holstein calves were separated from their dams immediately after birth, weighed, and placed in individual pens. Then at 28 ± 2 d, calves were randomly assigned to either an individual pen (n = 16 calves, 1.5×2 m2) or group pen (4 calves/pen, n = 16 calves, 3×4 m2). All calves were offered a step-up/step-down method of milk feeding (4, 6, 8, 6, 4, and 2 L/d) and weaned at d 63. The study finished when calves reached 90 d of age. Feed intake was determined daily. Calves were weighed at birth, 28, 63, and 90 d of the age. Body measurements including body length, body girth, withers height, heart girth, hip height, and hip width of the calves were measured at the start and end of the study. Blood samples were collected at d 4 before and d 4 after weaning for measurement of glucose, cholesterol, and BUN concentration. Behavior parameters (playing, cross-sucking, grooming, and non-nutritive oral behavior) were monitored by visual observations of all calves at the 60 and 89 d of age for a period of 24 h. Calf health was checked every day for fecal scoring, general appearance scoring, and respiratory scoring. Also, diarrhea and pneumonia diagnoses and treatment of calves were recorded. On 50 and 80 d of age, ruminal fluid samples were collected from male calves for the measurement of pH and analysis of volatile fatty acids.
Results and Discussion: There was no significant difference between housing for starter intake, total dry matter intake, and ADG during pre-weaning, post-weaning, and the total period of the study. Also, BW (birth, 28, 63, and 90 d) and skeletal growth (initial and final of the study) were not affected by housing. We observed no housing effect on glucose and BUN plasma, however, cholesterol concentration was greater in individual calves than group calves at pre- and post-weaning, which is probably related to the greater stress of individual calves than group calves during weaning. Ruminal pH, total VFA concentration, the concentration of acetate, propionate, butyrate, iso-butyrate, isovalerate, valerate, and acetate to propionate ratio in ruminal fluid were similar between treatments. There was no difference between treatments for the frequency and number of days with general appearance (score ≥2), diarrhea (score ≥3), and pneumonia, as well as medicated days for both diarrhea and pneumonia during the pre-weaning, post-weaning, and total period of the experiment, indicating that calves, in general, were healthy. These results are probably attributed to good management of colostrum feeding, bedding, hygiene, regular health monitoring and disease diagnosis, and small group size. In the current study, non-nutritive oral behaviors were greater in individual calves than group calves during pre-weaning. However, cross-sucking, grooming, and playing activities were greater in group calves than individual calves during pre-weaning. During post-weaning, behaviors were not affected by housing. Behavioral results show that group housing improves the welfare of calves at weaning.
Conclusion: In general, the results showed that type of housing (group or individual) did not affect performance, rumen fermentation, and health of calves. While group housing can lead to improving the welfare of calves (increase the play and grooming, and decrease the non-nutritive oral behaviors).We suggested that calves can be grouped in good health if housing is properly managed.