Husbandry procedures at the point of lambing with reference to perinatal lamb mortality
F. Douglas, N.D. Sargison, University of Edinburgh, Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, UK. EH25 9RG
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A questionnaire was created, then piloted and refined before distribution to all Royal (Dick) School of Veterinary Studies veterinary students ahead of some undertaking lambing extra mural studies. Questions focused on tasks that are carried out to keep ewes and lambs healthy and in a good welfare state during the lambing period, with the aim of allowing presentation of descriptive survey data. Involvement of veterinary students in a retrospective survey is a proven method to provide representative and informed observational data on lambing management practices and perinatal lamb mortality. Our survey suggests that implementation of no single animal husbandry task or procedure will enhance perinatal lamb survival and highlights the need for better data and applied research in the field of perinatal lamb mortality. The widespread use of prophylactic oral and parentral antibiotic lamb treatments at birth is worrying in the context of responsible use of antimicrobial drugs. When considered alongside the percentage of farms not undertaking basic animal husbandry and hygiene methods, our survey highlights opportunities for reduced dependence on medicines through better animal husbandry at the time of lambing.
Perinatal mortality reduces the number of lambs sold per ewe and consequently impacts negatively upon the economic sustainability of sheep farming. Figures quoted for the incidence of perinatal lamb mortality in UK flocks are mostly anecdotal, and need to be interpreted with caution, due to considerable variation within and between flocks, districts, seasons, sheep breeds, ewe age groups, farm management systems (Wooliams and others 1983), and record keeping. Any management practices which ensure correct nutrition of pregnant ewes, avoidance of dystocia, provision of energy and protective antibodies through colostrum, and a strong maternal bond will enhance the perinatal lamb survival rate (Mellor 1983). However, the relative importance and practicality of such practices differ between farms, and in the absence of accurate records or survey data (Green and Morgan 1993), their impact is unclear.
Lambing is the critical time when the benefits of preparation throughout the year are realised. Careful shepherding is required to minimise disturbance of lambing ewes, thus enabling the establishment of a good ewe-lamb bond and enhancing the survival of newborn lambs (Warren 1975). The need for careful skilled assistance of some lambing ewes is inevitable and a clear plan is required to avoid prolonged suffering. This includes preparation of lambing equipment in advance and guidelines about when to intervene or seek assistance. Provision must be made for the prevention of disease in newborn lambs and management of both ubiquitous problems and flock specific diseases.
UK veterinary students must undertake periods of farm animal husbandry-focussed extramural studies (EMS). Most opt to spend time working on a cross section of farm types during lambing, affording a unique insight to certain practices that may impact upon perinatal lamb survival. We enlisted the help of Batchelor of Veterinary Medicine and Surgery (BVM&S) undergraduate veterinary students while engaged with their extramural studies, to undertake a nationwide audit of perinatal lamb mortality and husbandry procedures at lambing time in UK sheep flocks. Our survey aim was to describe the relationship between management interventions and perinatal mortality.
A questionnaire was created using the Bristol Online Survey tool ( then piloted and refined before distribution to all Royal (Dick )School of Veterinary Studies veterinary students ahead of some undertaking lambing extramural studies. The questionnaire is provided as supplementary material. Questions focused on tasks that are carried out to keep ewes and lambs healthy and in a good welfare state during the lambing period, with the aim of describing those procedures that might impact upon lamb survival. Respondents were asked to assign a subjective overall rating of farm husbandry as a ‘student quality score’ (SQS) of zero (awful) to 5 (excellent).
Each husbandry procedure was evaluated against perinatal mortality and assessment scores using Minitab 17 software ( A Krushkal Wallis test was used to evaluate statistical significance for each relationship. Chi square with cross tabulation and Fisher’s exact tests were carried out for relationships deemed significant. Eight of 134 responses, representing 134 farms, containing invalid or no values for perinatal lamb mortality were rejected from the analyses of relationships between mortality and 14 positive husbandry procedures for lamb survival, but all were retained for other analyses and presentation of quantitative data.
The response rate for the questionnaire was 16 percent of all BVM&S students, being strongly biased towards those in their first and second years undertaking lambing EMS for the first time. 94.8% of responses concerned farms with housed sheep. Perinatal lamb mortality rates were normally distributed around a mean of 10% (± 6.7% SD), ranging from 1% to 30%. However, only 11.9% of respondents reported dead lambs to be counted accurately (Fig 1).
Descriptive statistics for different husbandry procedures and their relationship to the reported perinatal lamb mortality rate are shown in Table 1. There was no significant correlation between perinatal lamb mortality rate and any single husbandry procedure.
Of those farms having a SQS less than, or equalling average, 79% had a perinatal lamb mortality rate ≥10%. The “positive predictive value” for the SQS was 57.4%, representing the likelihood that a farm with good husbandry will have an acceptable mortality rate. The negative predictive value was 78.6%, suggesting that farms with husbandry perceived as being poor are more likely to have higher perinatal lamb mortality rates. SQS did not have a statistical association with other data gathered from the survey, except the use of lambing ropes (p=0.007) and stomach tubes (p=0.041). Of those farms using ropes as lambing aids, 85.4% had a SQS greater than average, while farms with a score greater than average were 50% more likely to be using ropes. However, this only represents correlation, not causation. Farms using stomach tubes were about four times more likely to have a SQS above average. This could be interpreted that the use of stomach tubes improves lamb survival, but the number of farms not using stomach tubes at some point was too small to support a conclusion. There was no significant association between the number of positive husbandry procedures undertaken and perinatal mortality.
Involvement of veterinary students in a retrospective survey is a proven method to provide representative and informed observational data on lambing management practices and perinatal lamb mortality (Binns and others 2001). Accurate data recording is an essential aspect of improving the efficiency of livestock production (McNeilly 2017), hence the failure to record data on perinatal lamb mortality on the majority of farms in our survey is cause for concern.
Our survey suggests that implementation of no single animal husbandry task or procedure at the time of lambing will enhance perinatal lamb survival. This is not unexpected, as significant correlations would be unlikely where few farms undertake, or do not undertake specific practices, while our focus on management practices did not take ewe nutrition dystocia or disease into account. Our SQS was influenced by assessment of procedures that are taught as dogma within the veterinary curriculum, and would inevitably have been biased by experiences of perinatal lamb mortality itself. While the correlation between SQS and lamb mortality cannot imply causality, it shows that not following good husbandry procedures as a whole carries a risk of higher mortality, highlighting opportunities for general improvements in animal husbandry and care at lambing to improve lamb survival. The results also show the need for better data and applied research in this area.
The use of prophylactic oral and parentral antibiotic lamb treatmets at birth on 68% and 26%, respectively, of farms is worrying in the context of responsible use of antimicrobial drugs (Veterinary Record News Section 2016). When considered alongside the percentage of farms not undertaking basic animal husbandry and hygiene methods such as using obstetric lubricant (26%), or lambing gloves (60%), our survey highlights opportunities for reduced dependence on medicines through better animal husbandry. Better understanding is needed of those husbandry procedures at the time of lambing that can be adopted to reduce the perceived or actual needs for mass antibiotic treatments of perinatal lambs.
References
BINNS, S.H., Cox, I.J., Rizvi, S. & GREEN, L.E. (2001) Risk factors for lamb mortality on UK sheep farms. Preventive Veterinary Medicine 52, 287-303
GREEN, L.E. & MORGAN, K.L. (1993) Mortality in early born, housed lambs in south-west England. Preventive Veterinary Medicine 17, 251-261
McNEILLY, T.N. (2017) Editorial: Global food security via efficient livestock production: targeting poor animal husbandry. Veterinary Record 180, 276-277
MELLOR, D.J. (1983) Nutritional and placental determinants of foetal growth and consequences for the newborn lamb. British Veterinary Journal 139, 307-324
VEERINARY RECORD NEWS SECTION (2016) Sheep sector responds to antibiotics challenge. Veterinary Record 179, 373
WARREN, H.D. (1975) Easy care shepherding. Proceedings of the Sheep and Beef Cattle Society. New Zealand Veterinary Association 5, 76-78
WOOLIAMS, C., WIENER, G. & MACLEOD, N.S.M. (1983) The effects of breed, breeding system and other factors on lamb mortality. 3. Factors influencing the incidence of weakly lambs as a cause of death. Journal of Agricultural Science 100, 563-570
Table
Husbandry procedure / Number of farms / Percentage of farms (n/134x100) / Significance (p value) for relationship with reported perinatal lamb mortality rate.Iodine treatment of navels / 128 / 95.5 / 0.224
Prophylactic parenteral antibiotic treatment at birth / 35 / 26.1 / 0.885
Prophylactic oral antibiotic treatment at birth / 91 / 67.9 / 0.712
Use of heat lamps / 103 / 76.9 / 0.438
Use of a warming box / 70 / 52.2 / 0.331
Use of waterproof lamb jackets / 27 / 20.1 / 0.165
Feeding via a stomach tube / 128 / 95.5 / 0.950
Feeding via a bottle / 127 / 94.8 / 0.645
Wearing gloves when assisting lambing / 54 / 40.3 / 0.294
Using lubricant when assisting lambing / 99 / 73.9 / 0.329
Use of ropes as a lambing aid / 82 / 61.2 / 0.261
Use of intraperitoneal glucose injection / 40 / 29.9 / 0.499
Spray identification of lambs to match dams / 129 / 96.3 / 0.816
Castration practiced / 103 / 76.9 / ns
Tail docking practiced / 123 / 91.8 / ns
Enemas given / 12 / 9.0 / 0.477
Supplementary lamb feeding / 131 / 97.8 / 0.118
Fostering by bathing in birth fluids. / 121 / 90.3 / 0.0171
Adopting a lamb onto a ewe with no lambs. / 115 / 85.8 / 0.371
Adopting a lamb onto a ewe with one lamb. / 115 / 85.8 / 0.155
Using an adopter crate. / 88 / 65.7 / 0.719
Tying a ewe up with a halter to adopt lambs. / 71 / 53.0 / 0.172
Skinning a lamb and using it as a coat for another. / 92 / 68.7 / 0.586
1. p=0.076 with Fisher’s exact test
ns not significant
TABLE 1: Husbandry procedures undertaken at lambing on 134 farms and their relationship to perinatal lamb mortality rates. A Krushkal Wallis test was used to evaluate statistical significance for the relationship, shown as p-values.