Factors affecting neonatal survival on beef and sheep farms

Neonatal survival on British beef suckler and sheep farms

Median lamb mortality in the first 21 days of life was 8.2% (6% top quartile), while median suckler calf mortality was 4.4% (top quartile 2.5%). Most of these losses occurred in the first week of life, with a median mortality to 7 days of 8.1% for lambs and 4.0% for calves.

Interestingly, mortality rates did not vary by farm size or number of breeding females per full time equivalent staff member, suggesting that large farms can achieve comparable performance to smaller farms, whilst the quality of supervision may be more important than the ratio of staff to breeding females.

Barriers and enables to improving neonatal survival

Both the survey and interview responses demonstrated that neonatal survival is important to farmers, who demonstrate autonomous motivation to improve neonatal survival. This means that farmers wish to improve neonatal survival because it is important to them, not because they are concerned about what others would think about them. Whilst farmers are confident in their abilities to improve survival, they tend to underestimate neonatal mortality on their farm relative to British averages. Of particular note is a cultural stigma around neonatal losses, which limits farmers in discussing their experiences with their peers and even in some cases, with their vet.

Another significant barrier to improvement in neonatal survival was a poor correlation between farmer reported mortality rates in one season and mortality rates recorded by this study in the subsequent season. This would suggest that performance is highly variable between seasons and/or many farms do not record performance accurately. This was explored in more depth and whilst most suckler farmers have access to reliable mortality records, 2 in 5 sheep farmers have no record of neonatal mortality at all.

Whilst many farmers were aware of important drivers of neonatal survival, best practice industry advice with respect to managing neonatal survival was not consistently followed, particularly with respect to colostrum management and genetic selection.

Antibiotic use

This study also looked at antibiotic use on both sheep and beef suckler farms. Of particular note are the significant proportion of beef and sheep farms that are able to manage infectious diseases without purchasing critically important antibiotics such as fluoroquinolones, 3rd/4th generation cephalosporins and colistin.

Reductions in the use of preventive oral antibiotics in lambs are challenging, as their use has historically been viewed as a part of best practice in avoiding losses. However, preventive antibiotics have been reduced or withdrawn successfully on some farms in this study, whilst oral antibiotic treatment at birth made no difference to lamb outcomes in the experimental study.

Biological determinants of lamb survival

The experimental study in this project demonstrated that poor long term protein status in late pregnancy (indicated by low blood albumin) is predictive of increased lamb losses between scanning and 24 hours old, whilst twin born lambs with a low (under 24 mg/ml) serum antibody (IgG) concentration are more likely to have poorer growth rates. As shown by previous studies, poor energy balance in late pregnancy (elevated beta-hydroxybutyrate) is predictive of a low lamb serum antibody concentration, indicating that lambs born to ewes in negative energy balance are at increased risk of absorbing insufficient colostrum antibodies from the ewe.

Funding and research partners

This project was funded by the three British levy boards: The Agriculture and Horticulture Development Board (AHDB) Beef and Lamb, Hybu Cig Cymru (Meat Promotion Wales) and Quality Meat Scotland.

This project was led by the University of Edinburgh in collaboration with the University of Liverpool, University of Nottingham and Synergy Farm Health Ltd.

Project aim

The aim of this project is to benchmark, define the risk factors for, and propose an integrated control plan to improve survival and reduce morbidity and antibiotic use in neonatal lambs and suckler in Great Britain.

Project plan

The project consists of four work packages. The first three work packages (WP1-3) aim to capture current practice on GB sheep and suckler farms, define the barriers and enablers to improving neonatal survival and explore the biological determinants of neonatal lamb mortality and morbidity.

The final work package (WP4), integrates the findings of WP1-3 with existing knowledge in the literature, to develop and pilot a neonatal survival and sustainable antibiotic plan.

Current progress

The project started in September 2018 and is due to finish August 2020. WP1-3 are now largely complete, with these three work packages now in their final data analysis and publication phase. WP4 is currently in the pilot phase, with the control plan being piloted on approximately 40 farms in England and Scotland.

Key findings to date

• In the farms that participated in the study:
  • Mean lamb mortality in first month of life was 10.4%
  • Mean calf mortality in first month of life was 7.5%
  • The majority of mortality in lambs (9.5%) and calves (6.0%) occurred in the first 7 days of life
• Neonatal survival is important to farmers, who demonstrate autonomous motivation to improve neonatal survival and feel confident in their abilities
• Reported management practices are not always in keeping with current industry guidelines, suggesting that time and resources are not necessarily being deployed in the most productive ways
• Medicines records show that most beef and sheep farms are able to manage infectious disease, whilst maintaining production, without purchasing fluoroquinolones, 3^rd/4^th generation cephalosporins or colistin
• Prophylactic oral antibiotic treatment at birth in a well-run flock does not improve lamb survival or performance
• Poor long term protein status in late pregnancy (low blood albumin) is predictive of increased lamb loss between scanning and 24 hours old and an increase in the number of lambs identified as poor at birth (Figure 1). Further work is necessary to determine whether this is due to concurrent disease (e.g. liver fluke) or poor dietary protein supply during pregnancy
• Lambs identified as poor at birth have poorer live weight gains to weaning
• Serum total protein at 8-24 hours old trends lower in lambs that die before weaning (Figure 2, p=0.07 in a flock with an overall mortality rate between 24 hours old and weaning of 4%)

Figure 1: Blood plasma albumin concentrations two weeks prior to lambing in ewes that lost lambs between scanning and tagging at 24 hours old versus those that did not lose a lamb

Figure 2: Lamb serum total protein (TP) concentration at 8-24 hours old plotted against death from 24 hours old to weaning (4% overall mortality)

Knowledge gaps

This project has identified a number of knowledge gaps relating to neonatal lamb and suckler calf survival. These include:

• A poor understanding of the risk factors for low blood albumin in ewes in late gestation. These are likely to be nutritional in origin, however iceberg diseases e.g. Johne’s disease and other diseases like lameness and liver fluke may also be important. This is currently being investigated via a follow on project with HCC
• A limited evidence base to guide when to intervene during lambing/calving and the best way of learning these skills
• A limited evidence based to inform the design of appropriate field shelters for lambs
• A limited evidence base as to the best approach in the management of cows that lose calves in a suckler herd and the optimum management of triplet lamb litters
• A lack of cost-benefit analysis relating to the level of supervision at lambing/calving (training vs. experience, ratio of stock to staff, continuous vs. intermittent supervision)

Project funding

The work was part financed from the £2 million fund (rising to £3.5m in April) of AHDB red meat levies ring-fenced for collaborative projects which is managed by Britain’s three meat levy bodies: AHDB, HCC and QMS.

The fund is an interim arrangement while a long-term solution is sought on the issue of levies being collected at point of slaughter in England for animals which have been reared in Scotland and Wales.