52 research outputs found
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Analysis of pre-weaning feeding policies and other risk factors influencing growth rates in calves on 11 commercial dairy farms
Growth rates in pre-weaned calves influence their health, age at first calving and lifetime productivity. Many farms restrict milk rations to encourage solid feed intake and facilitate early weaning, but this can compromise growth. This study determined the milk feeding policies and associated growth rates on 11 commercial dairy farms in South East England, each following their normal management regime. Between 26 and 54 heifers were recruited per farm, providing a final cohort of 492, of which 71% were pure Holstein. Information on calf rearing practices (feeding, weaning, housing) and health was collected via questionnaires and weekly observations. Estimates of actual milk fed (kg solids) between 1 and 63 days were calculated for individual calves. Morphometric data (weight, height, length) were taken at weeks 1, 5 and 9 and at a median age of 7.5 months and growth rates were calculated. Most calves were fed milk replacer via automated feeders (four farms), teat feeder (one) or buckets (four) whereas two farms provided drums of acidified waste milk. Farms fed between 4 and 6 l/day of milk at mixing rates of 10% to 15%, providing 400 to 900 g/day of milk solids. Both skeletal growth rates and average daily weight gain (ADG) increased in the second month of life compared with the first: height growth from 0.17±0.14 to 0.25±0.16 cm/day and ADG from 0.48±0.25 to 0.71±0.28 kg/day. Post-weaning heifers up to 7.5 months had height increases of 0.16±0.035 cm/day and ADG of 0.83±0.16 kg/day. From 1 to 63 days 70% of calves had growth rates <0.7 kg/day and of these 19.6% gained <0.5 kg/day. Mean ADG before 9 weeks varied between farms from 0.52±0.30 to 0.75±0.20 kg/day. This was related to the amount of milk fed at both a farm and individual calf level. Increasing the total milk solids fed between 1 and 63 days from 20.4 to 46.3 kg (the 10th to 90th percentile observed) was associated with an increase of 0.11 kg/day ADG. All farms had a wide variation in growth rates despite single feeding policies. Higher circulating immunoglobulin G and IGF1 concentrations were associated with better growth, whereas low temperatures in month of birth, high scores for diarrhoea, respiratory and umbilical disease and large birth size reduced growth. Many commercially grown dairy heifers therefore experienced growth restriction in the pre-weaned period, potentially reducing their health, welfare and productivity
Behavioural and physiological responses of individually housed dairy calves to change in milk feeding frequency at different ages
peer reviewedThis study aimed to use a range of non-invasive monitoring technologies to investigate the behavioural and
physiological responses of individually housed dairy calves to age at change in milk replacer (MR) feeding frequency.
Forty-eight Holstein Friesian calves were individually penned and fed MR (625 g/d) as solids in one of three feeding
regimes: (i) once-a-day feeding commencing at age 14 d (OAD14), (ii) once-a-day feeding commencing at age
28 d (OAD28) and (iii) twice-a-day feeding (TAD). Several behavioural (automatic activity sensors), physiological
(infrared [IR] thermography and heart rate variability [HRV]) and haematological indicators were used to examine
calf responses. Reduction in milk feeding frequency at 14 or 28 d of age increased daily concentrate intakes and
drinking water consumption throughout the pre-wean period. Calf lying behaviour was unaffected by reduction
in milk feeding frequency; however, TAD calves recorded a significant decrease in total daily lying time during
the post-wean period compared with OAD28s. There was no effect of treatment on IR eye or rectal temperature
throughout the experiment; however, there was an effect of age, with IR temperature decreasing as calf age
increased. OAD14 calves tended to have decreased HRV at days 14 and 16, which is suggestive of an increased
stress load. The findings suggest that under high levels of animal husbandry and whilst maintaining the same
amount of milk powder/d (625 g/d), reduction in milk feeding frequency from twice to once daily at 28 d can occur
without significant impact to behavioural, performance and physiological parameters assessed here
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