Performance and Behavioural Effects of Separating Dairy Cows and Their Calves at Birth

a Knowledge Summary by

Michael Steele BSc(Hons), BVSc, MRCVS^1*

¹Inspire Cattle Solutions, 10 Granborough Road, Winslow, Buckinghamshire MK18 3BP
^*Corresponding Author (steelemi@elanco.com)

Clinical scenario

Separation of dairy calves within minutes to hours after birth is a popular concern raised with the public around intensive farming debates (Hotzel et al., 2017). Hotzel’s survey suggests that even when the public are given additional information on separation, this is not likely to increase public support. Although it has been well-established that risk of Johnes’ disease (Mycobacterium paratuberculosis) transfer is reduced with quick separation (Windsor & Whittington, 2010), there have been other publications indicating that the mother-calf bond may have beneficial effects on behaviour and learning capabilities of calves (Costa et al., 2016; Valnickova et al., 2015). It would be interesting to get an updated overview of behavioural effects, effects on production gains or losses and weight gain on both calves and mothers so that the general practitioner can give more informed advice to both the public and their farm clients.

The evidence

As this review combines two outcomes, that of behavioural effects of separation at birth and of performance characteristics of calves and mothers, I will address these two aspects separately, below:

Behaviour:

Many of the articles published on separation at birth address the aspect of how this can affect the mother-calf bond and focus on the interactions between both mother and calf and calf to calf interaction. Most of the evidence comes from observational research, either by videotaping, direct observation or vocalisation recording. Behaviours that were measured tended to be specific to those observed by a previous literature review that attempts to describe normal behaviour; seeking peers or the mother, interactions at play or calling (von Keyserlingk & Weary, 2007). Therefore, head movements, licking, ear “flicks” or movements towards audio stimuli and locomotor play are often parameters chosen to be measured. Of the behaviour reviewed in this paper, the following results appear to be reliable or consistent:

• There appears to be no effect on head movement, play, ear flicking or licking related to sex of the calf (Stehulova et al., 2017)
• Vocalisation of the mother is greater when there is a solid wall, but audio contact, between calf and mother at weaning/separation. Vocalisation behaviour increases with further contact with the mother from birth (Stehulova et al., 2017; Johnsen et al., 2015)
• Vocalisation of calves to mothers is higher when there is a solid wall, but audio contact, between calf and mother at weaning/separation. This also increases with further contact with the mother from birth (Stehulova et al., 2017; Johnsen et al., 2015)
• Vocalisation behaviour is specific to the mother’s own calf (Marchant-Forde, 2002)
• Vocalisation of calf to mother at separation increases with more time with the mother (Weary & Chua, 2000)
• When calves are separated from their mothers for short periods of time, they appear to lick and move their heads towards their mothers on returning. This behaviour increases with increasing length of contact time (in days) between mother and calf. The reverse is true of mother to calf in licking/head movements (Jensen, 2011)
• Individually housed calves have less social interactive skills and have lower cognitive test results when learning than socially housed calves (Costa et al., 2016)

From this, it is suggested that the calf to mother bond increases with increasing time to weaning and mothers/calves bond to their specific parents/offspring. These bonding behaviours however, appear to be present even after 6 hours from birth (Stehulova et al., 2017), so separation from this time onwards would appear to have a behavioural effect on the animals concerned.

Performance:

In terms of performance characteristics, articles tended to measure body weights at specific times to and after weaning, daily growth rates to and after weaning and milk yield of mothers. Some papers also measured feed intake of calves but also tried to relate this to growth in the same observations. In most experiments, separated calves are fed whole milk from the same herd in an attempt to equate composition but in those where replacer is used (Lee et al., 2009) composition and formulation become important. Daily intake of fed milk/replacer is also a factor influencing growth rates and this is addressed where possible however, intake of suckling calves is impossible to measure directly and the composition is very difficult to determine. Cows that are milked in the parlour but who are still suckling may have very different fat/protein components that their calves are given access to. This makes direct comparisons of growth rates in suckled and separated calves less easy to determine.

Weight gain:

• Calves appear to gain more weight when suckling with their mothers, increasing with time up to 2 weeks after birth (Valnickova et al., 2015)
• Calves fed whole milk vs. milk replacer with similar ingredients have better growth rates (Lee et al., 2009)
• Calves staying with their mothers for up to 6 weeks, gained weight at 3 times the rate of separated calves up to 6 weeks (Roth et al., 2009)
• Calves on automatic feeders gain more weight than suckled calves after weaning (0.4 kg/d) (Roth et al., 2009)
• Calves on automatic feeders eat 16–19 kg more concentrates (total) until weaning than suckled calves (Roth et al., 2009)
• Calves kept with their mothers gain 25–28 kg more than automatic fed calves to weaning (Roth et al., 2009)
• The longer calves are with their mothers, the more weight they gain in comparison to weaning (Kisak et al., 2011)
• There is no evidence of any difference between group or individually housed calves or separated/suckled calves on disease rates (Costa et al., 2016; Grondahl et al., 2007; Kisak et al., 2011; Lee et al., 2009)

Milk Yield of mothers

• Mothers with calves give up to 14 kg less milk per day up to weaning, having effects into the lactation curve (Flower & Weary, 2001; Roth et al., 2009; Costa et al., 2016)

From this evidence, it appears that calves grow better if kept with their mothers and eat less concentrates in total up until weaning. However, the extra concentrate intake is more than compensated for with 14 kg extra milk per day from the mothers if they are separated. This, together with the information that growth rates from automatically fed calves increase after weaning compared to suckled calves, means that the overall production effects of separating from birth heavily support separation. Separated calves with restricted access to whole milk, or those fed milk replacer have not been found to have such favourable growth (Roth et al., 2009; Lee et al., 2009) and management beyond weaning becomes an increasingly important factor for growth as time increases from weaning, so longer-term separation effects are harder to determine.

As the behavioural effects of separation appear to be evident, but temporary, especially from the mother’s perspective, the positive performance effects support early separation.

Summary of the evidence

Acronyms: BW=Body Weight; MR=Milk Replacer; WM=Whole Milk; DMI=Dry Matter Intake

Appraisal, application and reflection

General Views

Of the 16 papers reviewed, 14 addressed populations of dairy cattle and 2 included beef animals (Stehulova et al., 2017; Valnickova et al., 2015). The latter articles were included as the methodology of the experiments were similar to those of the dairy practice articles and thus, results could add to this knowledge bank. The papers reflect global practices in mother and calf management, as papers were published from Latin America, North America, Asia and Europe.

Separation from the calf within 24 hours of birth appears to be very common (USDA, 2014) and many of the articles studied reflect this practice but some separated the calf 1–2 weeks later (Flower & Weary, 2001; Kisak et al., 2011).

Other management aspects reflect current dairy practices after separation such as keeping calves in individual pens shortly after birth, group housing calves and feeding them through an automatic feeder (USDA, 2014). If suckling is allowed to happen, then tethering cows is far less common in Western Europe but is still seen in Eastern Europe and Canada. However, comparing groups of calves combining all of these in one article produces too much management variation, especially when comparing growth or behaviour (Perez et al., 1985).

Ultimately, it is extremely challenging to fully evaluate the “stresses” involved in breaking the maternal bond between cow and calf, as many of the psychological aspects cannot be communicated or quantified. Therefore, the research groups have attempted to make a “best guess” by using some characteristics that can be measured, such as head rubbing, vocalisation, etc.

Behaviour

When studying behavioural outcomes, such as vocalisation, movements and lying times, it is preferable to have comparable conditions for both intervention groups. However, in many articles, the groups were either kept in different barns (Perez et al., 1985; Jensen, 2011; Johnsen et al., 2015; Wagner et al., 2012) or management routines have not been discussed sufficiently to explain the effect of background noise. Feeding and labour management can affect movements and vocalisation as cattle respond to people or machinery/feeding times. Only one article addresses the effect of “white noise” in their discussions (Marchant-Forde et al., 2002).

Many of the papers have very small population numbers in each group, with eight or less mother-calf pairs in each treatment group. This makes it difficult to interpret the statistical power of the results: P-values are often reported but confidence intervals are not, making discussion statements difficult to conclude from. This depends on the outcome studied: if these are growth rates, for instance, it is very difficult to tell from such small populations but if the outcome is number of vocalisation observations, then these are larger in number and more reliable conclusions can be drawn.

This becomes increasingly difficult when authors discuss results which are not scientifically significant (P > 0.05) or even as a trend (P > 0.10). Two of the papers report favourable results towards non-separation in their conclusions based on numerical differences when error bars clearly overlap (Wagner et al., 2015; ShinJae, 2013).

Experience of the mother may be a significant variable when assessing behaviours between mother and calf, so parity should be recorded clearly in each paper. However, the behaviour of heifers specifically is studied in only one article (Wagner et al., 2012).

When assessing the behaviour of calves kept in group pens, the affect of calves entering the pens at different times (when they are old enough to join the group) may affect behaviours such as head movements, number of movements, lying times, licking, sniffing, etc. This is only specifically addressed in one article (Roth et al., 2009).

Performance

When assessing growth rates and milk yields, there is far less room for error in recording, as these are absolute variables. Therefore, the papers addressing these outcomes are able to interpret the results with more reliable statistical discussion. However, due to such small population numbers, variables such as milk yield are unlikely to produce significant differences at P < 0.05 which can make solid conclusions hard to justify.

Growth rates of calves were often measured pre and post weaning and compared with either separation from birth, or access to the mother. In the separated groups, experimental methods tended to compare restricted and ad lib access to feed. This may have affected the reliability of results as it further reduced the population numbers of each group and added more confounding variables: growth is related directly to energy and protein intakes.

Growth of dairy heifers also varies with time: they tend to grow slowly in the first few weeks, accelerating in the later months and tailing off towards integration into the lactating herd (Coffey et al., 2006). Because of this, separating the calves at 2 weeks, 6 weeks or 12 weeks and comparing growth rates may have varying effects on future growth curves for those calves. Therefore, comparing directly between these and calves separated at birth may not reflect direct comparisons. Modifying the methods to include recording growth by smaller increments of time (each week, for example) may help to resolve this issue.

Again, similar to behaviours, growth and feed intakes may be affected by daily feeding routines/timing and social movements in pens, so in group housed situations, the comparisons of calves in one barn or pen vs. another may have more variables to consider than just separation from the mother.

Milk yields of cows are easy to record, as these are closely monitored on a daily basis when milking. Therefore, results such as 14 kg less milk per day (averaged over the pre-weaning period of 91 days) with ad lib suckled calves is a more reliable result (Costa et al., 2016; Roth et al., 2009). This result was obtained comparing similar parity and breed cows, chosen at random and grouped in similar proportions in pens but not mentioned to have been chosen by previous lactation yields. The cows were kept in identical pens and fed the same rations. The separated calves ate whole milk; the ad lib group averaging 8–10L intake/day and restricted group eating an average of 8 L/day. It is impossible to measure the actual intake of the suckled calves, making it more difficult to directly compare factors affecting growth rates of the two calf groups.

Separation at different points of early lactation may have effects on the long-term lactation curve overall but no authors have suggested or investigated this aspect over a 305 day lactation. There are more metabolic demands in the first 14–21 days in milk (McArt et al., 2012; Duffield et al., 2009), so separation beyond the first 48 hours may affect yields and lactation curves in varying ways depending on disease status, nutritional status, management and other factors. So comparing yields from cows separated at 1 and 2 weeks post calving (Kisak et al., 2011) may not be directly comparable with those separated at birth. Larger population numbers would be required to get reliable results.

Summary

Although suggestions can be made from the behaviour results reported in this review, it is difficult to draw a reliable conclusion that suckling may be beneficial over separation at birth from a mother/calf stress perspective. It seems that calves do vocalise and seek their mothers after separation the longer access they have to them but the actual stress impact of this is harder to determine. Mother-offspring bonding is an emotive human concern as humans have such vulnerable and helpless babies relative to ruminants. Assessing the impact of separation in cattle cannot be humanised, as their offspring are able to stand and find their own food within minutes of birth. Researchers can use a limited number of observations and physiological measurements to indicate stress but emotion will always be difficult to evaluate.

Due to the significant economic loss of milk when calves are allowed free access to their mothers and the increased risk of Johnes’ disease when they are, it is clearly economically beneficial to separate them within 24 hours. Evidence supports growth rates in calves before weaning are better when allowed free access to their mothers but from weaning to joining the dairy herd, the overall growth can be improved post weaning by early separation and ad lib access to an automated feeder. To make a general conclusion that separation results in better growth rates however, comes with words of warning: there are so many other confounding management factors to consider until the calves reach the milking herd, for example feed quality and access, parasitism and disease, that it would not be wise to assume that separation alone affects such long term ends.

Methodology Section

Search Strategy
Databases searched and dates covered:	3 databases: PubMed on NCBI Platform; 1980–2018 CAB Abstracts on OVID Platform; 1973–2018 Google Scholar; 2000–2018
Search terms:	PubMed on NCBI Platform: ((mother) AND ((((cow$ OR cattle OR bovi*))) AND ((calf OR bovi* OR calve$)))) AND separat* CAB Abstracts on OVID Platform search 1973–2018: mother cow* OR cattle OR bovi* calf OR bovi* OR calve* separat* 1 AND 2 AND 3 AND 4 Google Scholar (cow mother calf calve$ separation)
Dates searches performed:	9 January 2019 (PubMed and Google Scholar) 13 January 2019 (CAB Abstracts)

Exclusion / Inclusion Criteria
Relevance to PICO, sufficient evidence level, answers the clinical question
Exclusion:	Non-bovine; Cellular and molecular effects; In vitro work; behavioural responses recorded a long time after separation event (>30 days) Conference proceeding with such poor quality science and report that it was impossible to review
Inclusion:	Bovine; Behavioural; Performance outcomes

The author declares no conflicts of interest.

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