DAIRY RESEARCH DAIRY RESEARCH
IS IT TIME TO CHANGE UP HOW CALVES ARE HOUSED? Housing calves in pairs to increase social behaviours will become increasingly important in the future By Oisin Graydon and Marlene Paibomesai CONTRIBUTOR
T
he majority of dairy farms in Canada raise calves individually. In the Canadian National Dairy Study, 63 per cent of respondents indicated calves are raised individually in pens or hutches (1). Events during the first few months of a calf's life, such as separation from the dam, a change in diet at weaning and, eventually, introduction to a larger group of calves, can be stressful. Stress can impact disease susceptibility, growth and welfare by decreasing feed intake and negatively impacting a cow’s immune system. In addition, the expression of natural behaviours by domesticated animals, such as play and social interaction, is a growing area of public concern for all livestock farms. Isolation of herd animals at any time in the production cycle limits their ability to engage in social interactions. This could drive an expectation of raising calves in groups or in pairs to promote natural behaviours and maintain public trust. A collection of research over the last five years has found raising calves in pairs can decrease stress and improve growth and welfare, so is it time for change? Calves housed individually allow the producer and-or calf manager to observe them more easily and ensure they are receiving all they need. Sickness is limited when calves are individually housed because they have less calf-to-calf transmission, and sick calves may be identified sooner when separated (2). However, disease arises from more than just housing style; there are many factors that contribute to disease, with stress being a large contributor to disease susceptibility (2). Housing calves in pairs can reduce stress, increase average daily gain (ADG) and feed efficiency and improve cognitive development.
saving labour and production costs. Another study found calves placed into pairs at 14 days of age ate for longer periods, spent more time in the feed station, performed more social behaviours and spent more time playing. This means producers may be able to individually house calves for observational purposes for the first 14 days and still benefit from pair-raising. However, it is recommended calves be paired earlier than 14 days to benefit from improved growth in the pre-weaned phase (6). Pair-raised calves had higher ADG, starter intake before weaning and post weaning starter intake as shown in Table 3. Raising calves in pairs can influence more than just how much they eat and grow; it can also influence their social development. It is believed play behaviour in calves can promote emotional and physical development, resulting in a more stress-resilient and easier to handle cow. When animals are isolated, they are unable to practice activities that require social contact or copying others' movements (social learning) (7). This can impact how they handle stressors later in life, such as responding to novel changes, Table 1: Time spent playing and feeding and willingness to approach calf handlers of calves raised as pairs, individually or with the dam. Adapted from Duve, L.R et al. 2012. Duration of play (seconds)
Time feeding (seconds)
Time to approach the handler (seconds)
Pair-raised - high
30.3
77
84.88
Pair-raised - low
32.2
810
Individual - high
36.2
314
Individual - low
2.41
629
Still on dam - high
24.9
322
146
194
BEHAVIOUR CHANGES OF PAIR-RAISED CALVES In stressful situations, calves can often display behaviours, such as vocalizations, latency to eat, fearfulness of outsiders and decreased duration of play (3,4). Table 1 show data collected on a small herd of 40 calves to examine how isolation or companionship and diet during weaning would influence calf behaviours. The study found calves raised in pairs spent significantly more time feeding on solids, were much faster to approach a novel person and spent more time playing (2). Table 2 show data collected in another study that recorded the amount of vocalizations calves made during a three-day weaning period while they were housed in different conditions. The study found individually housed calves vocalized more throughout weaning than calves housed in pairs (3).
FEEDING BEHAVIOUR AND AVERAGE DAILY GAIN INCREASES WITH PAIR-RAISED CALVES When calves undergo changes in their diet, it can often decrease dry matter intake and result in reduced weight gain. This is also accompanied by increased stress often due to changes in group size and introduction to a new group of calves. Decreased ADG means it will take longer to reach target weights for weaning or breeding and require more feed to reach that milestone. When raised in pairs, calves start eating sooner, visit the feeder more often, spend more time at the feeder and have a higher feed intake after a diet change (4, 5). Improving these feeding behaviours is beneficial to producers because it can decrease the time to target weights, 30
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Table 2: Vocalizations (calls per hour) of individually raised and pair-raised calves. Adapted from Bolt, S. L. et al., 2017. Pre-weaning
During weaning
Postweaning
Individually raised
0.86+/-1.7
2.76+/-1.14
109.38+/51.40
Pair-raised at 5d old
0.10+/-0.9
0.73+/-0.21
26.08+/20.16
Pair-raised at 28d old
0.10+/-0.13
0.46+/-0.16
45.42+/26.77
Table 3: Average daily gain (ADG), pre- and post- weaning starter intake of calves raised as individuals, early or late paired raised. Adapted from Costa, J. et al., 2015 . ADG (kg/d) Pre-weaning Post
starter intake (kg/d)
weaning starter intake (kg/d)
Pair-raised
0.31+/-0.07
0.18+/-0.03
2.20+/-0.22
Individual
0.17+/-0.07
0.07+/-0.03
1.09+/-0.25
Pair-raised after 15d
0.18+/-0.06
0.05+/-0.03
1.26+/-0.33
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