Evaluation of raising dairy calves by foster cows in Mexico.

Our aim was to evaluate a foster cow-calf rearing system on the adoption or acceptance of fostered calves, milk production and udder health, as well as calf health and weight gain, and to compare this fostering system to traditional rearing. The foster group (FG) consisted of 8 cows each suckling 3 fostered calves with continuous contact. The control group (CG) was a conventional milking system, whereby cows and control calves were kept separate. The duration of the experiment was 8 weeks. Behavioural observations were carried out after the calves were introduced to the FG to find out if and how many calves were adopted or accepted (complete or incomplete maternal behaviour expressed, respectively). Milk production (let down) was recorded daily for CG and once a week for FG (after 8-h of no suckling). Milk samples were collected once a week from both groups for California mastitis test, Wisconsin test, and somatic cell count. A daily record of the incidence of diarrhoea was made on the calves and they were weighed once a week. Results showed that six of the eight FC cows had adopted the three calves, whilst one adopted two calves and accepted one and one adopted one calf and accepted two. One other cow refused all three calves from the outset and was removed from the study. Milk production at a single milking was 2.52 ± 1.04 (mean ± sd) 10.07 ± 0.76 l for FG and CG, respectively. Udder health improved over time in FG as evidenced by a progressive reduction in SCC. The average weight gain for FG calves was higher than for CG (700.7 ± 97.7 vs. 471 ± 188.7 g/d). In conclusion, the foster-cow rearing system was well received by most cows, the udder health on FG showed an improvement in comparison to the CG, and a higher weight gain was found in FC compared to the CC in a traditional rearing system.