Impact of enhanced compared to restricted milk feeding on the health and well-being of organic dairy calves

In an experimental multi-site study, we investigated the effects of an increased level of milk feeding (10-12 l/d, ≙ 14-16% of the calves’ body weight, ‘MilkPlus’ (MP)) compared to common restricted milk feeding (6-8 l/d, ≙ 10-12% of body weight, ‘Control’ (C)). Data from 10 dairy farms (nine certified organic, one near-organic), originally applying restricted milk provision by bucket-feeding in Austria (Fleckvieh; 4 farms) or Germany (Holstein Friesian; 6 farms) were analysed concerning calf welfare. Per farm, 6-15 female calves were randomly allocated to the treatments MP and C, which were applied over the milk feeding period of 13 weeks, with about three weeks of milk reduction starting in week 11. Data were recorded during the milk feeding period in weeks of life 3/4, 7/8, 11/12 (±2 days) as well as after weaning in week 15/16. This included welfare measures relating to behaviour, observed from video-recordings (manipulating other calves, manipulating objects, vocalization, duration of feeding solid feed; observation time: 320 min per day distributed over 16 h), to health (clinical scoring), and to performance (weight gain). MP calves tended to have higher body weights at the end of the milk feeding period (weeks of life 11/12: MP 111.0 kg, C 104.4 kg) and shortly after weaning (weeks of life 15/16: MP 138.7 kg, C 131.1 kg; pgroup*time point =0.095) and had higher daily weight gains during the milk feeding period (week 3/4 to 7/8: MP 939 g/d, C 818 g/d; week 7/8 to 11/12: MP 1082 g/d, C 956 g/d; p=0.025). C calves manipulated other calves more frequently only in week 3/4 (MP 2.6, C 4.5 times per 320 min, p<0.001), with no differences later. Clinical health and manipulation of objects showed no association to milk amounts, but the latter decreased when feeding duration of solid feed increased (p<0.001). C calves spent more time with solid feed during the milk feeding period (week 7/8: MP 9.8% of observed time, C 12.0%, week 11/12: MP 14.4%, C 17.7%; p=0.008). Calves’ vocalization was on average on a low level, but with large individual variation. MP calves vocalized more after weaning (MP 1.6, C 0.5 times per 320 min, p