Nutritional Management and Metabolic Profiling of Suckler Cows
17 October 2024There are many factors involved in achieving this goal, and nutrition plays a key role but can often be over-looked. This guide will cover how to successfully plan nutrition at key stages for the suckler herd, and tools to assess and monitor the nutritional status of the herd, to achieve cows successfully rearing a calf every year.
Good nutritional management requires year-round planning. Reproductive efficiency is a major factor in profitability and production in the suckler herd. A key performance indicator for cow efficiency is over 90% of cows put to the bull should have a calving interval below 370 days. However, in 2021 the mean calving interval of the Scottish suckler herd was c.400 days. The conditions for eligibility to the Scottish Suckler Beef Support Scheme has also changed, with an initial calving interval threshold set at 410 days (or less). In the future this threshold may reduce further.
Nutrition planning
There are three main strategies that are involved in planning and monitoring nutrition of the suckler herd: Monitoring nutritional status using body condition scoring; Ration formulation alongside a nutritionist or feed adviser, and monitoring nutritional status using metabolic profiling to assess if the ration is sufficient.
Body condition scoring
A quick and effective management tool is body condition scoring carried out at key times, particularly prior to bulling (around 2 months after calving), the end of summer/housing and the last two months of pregnancy. For spring calvers aim for a score 2.5 at calving and for autumn calvers a condition score of 3.0.
Condition scoring requires a hands-on approach, assessing by eye is useful but laying on a hand for 5-10 seconds per cow is a better measure of fat cover. It is essential to condition score as early in pregnancy as possible, where condition is off-target weight changes need to be made gradually, (no more than 0.5kg/day).
Assess body condition at the tail head and spinal processes (circled in image 1) regularly.
Over fit cows (over BCS 3.5) with excess fat around the pelvic canal can lead to complicated and assisted calving, in addition to cycling problems and delays in conception. However, although fit cows are often thought of as the bigger risk at calving, a study by the University of Edinburgh showed that it was thinner cows (below BCS 2.5) that had a greater risk of calving problems. In addition, an SRUC study showed that lean cows in late pregnancy (less than BCS 2.0) had calves that were 7% less vigorous, particularly those that had lost substantial amounts of condition over pregnancy.
Thin cows lack the energy reserves needed at calving and can have problems with weaker calves, poorer colostrum and lower milk yield. The nutritional demands for breeding are competing with early lactation in thin cows and this can delay cycling and embryo losses can be high.
Therefore, limiting quality or quantity of feed to cause severe and sudden weight loss should be avoided as it will likely constrain energy available to the cow during delivery of the calf and will risk poor calf vigour.
For more information on condition scoring please visit: https://www.sruc.ac.uk/media/42whghsz/tn756-body-conditioning-scoring-suckler-cows.pdf
A visual guide to condition scoring suckler cows has been produced by the National Animal Disease Information Service: https://www.nadis.org.uk/disease-a-z/cattle/condition-score-bcs-in-beef-herds/.
Ration formulation
Everyone that is involved in nutrition of the herd including the stock person, operator of the feed wagon, farm manager and nutritionist should be involved in the feed plan. Work with a trusted feed adviser or nutritionist to formulate suitable rations and regularly communicate. Feedback is important to ensure the ration formulated on paper is working in practice. For example, are cows clearing up too quickly or is feed access an issue and they aren’t achieving dry matter intakes that were predicted? This allows adjustments to be made if needed and ensures everyone is on the same page.
Analyse your forage
Forage (silage, hay, haylage) which forms the basis of most suckler cow rations must be analysed, forage will vary year-to-year and from farm-to-farm so having an accurate, up to date analysis is essential for appropriate ration formulation.
Know your average weight
Weighing a selection of sucklers to get an accurate average of the group is also a useful exercise as this is often underestimated when rationing. Grouping suckler cows at housing according to BCS, ideally three management groups of fit cows (above BSC 3), those in target condition for calving (BCS 2.5-3) and thin cows (less than BCS 2.5) with first calvers, second calvers and those carrying twins. If cows are outwintered, keep leaner cows separate or house them to offer good forage and concentrate if needed. This allows appropriate rationing for each group to achieve the target of around 2.5-3.0 at calving.
Monitor your calving spread
Calving spread also has an impact on nutritional management, a compact calving block makes it much easier to manage nutrition as requirements increase in late pregnancy. The industry target is for 80% of cows to be calved within the first 6 weeks of the calving period. Where calving spread is 9-12 weeks long it’s difficult to ration cows on their calving date, therefore advice should be sought based on the forage available and expected calving period.
Consider minerals in your ration
Minerals are another important aspect of ration formulation that should not be forgotten, more information on mineral nutrition can be found here: https://www.fas.scot/downloads/guide-to-mineral-nutrition/
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Metabolic profiling
Metabolic profiling involves blood testing cows at keys times in the production cycle, such as pre and post calving to assess nutritional status. Recent work by Edinburgh University and SAC Consulting in suckler herds as seen an increase in uptake of those using metabolic profiling in beef herds. Careful interpretation of metabolic profiles for suckler cows is important due to the influence of management and breed.
When to sample
The best time to blood sample is in late pregnancy, preferably within one month of calving. A minimum of six cows should be sampled, ideally from the early calving group that are one month pre-calving. Cows should be on their current ration for at least two weeks before sampling to ensure the results reflect the ration accurately.
Cows must have sufficient access to feed in the period before blood sampling. Any restricted access to feed in the previous 24-48 hours will affect the results with many blood parameters sensitive to changes in short-term feed intake. Ideally you want to time sampling 3-4 hours after feeding.
Additional rationing information required
When submitting samples the ration information provided alongside the blood samples helps provide a more accurate diagnostic.
Ration information to provide:
- Forage analysis
- Ration formulation or an estimate of forage and concentrate feed rate
- If cows are outwintered or housed
- If applicable what minerals or compound feeds are being provided with labels
- Information on cows sampled including average weight, breed and stage of pregnancy/lactation
Interpreting your results:
| Blood parameters | Optimum levels | What it means? | |
|---|---|---|---|
| Pre-calving | Post calving | ||
| Beta-hydroxybutyrate (BOHB) (mmol/litre) | <0.6 | <1.0 | One of the ketone bodies produced when cows oxidise fats or acetate/butyrate produced from mobilisation of body fat. This occurs at a slightly later stage in the fat mobilisation pathway compared to NEFA production. |
| Glucose (mmol/litre) | >3.0 | >3.0 | A short-term measure of energy supplied from the rumen. It is kept under tight hormonal homeostatic control (via insulin and glucagon), and so levels tend to be fairly stable, unless cows enter severe negative energy balance. |
| Non-esterified fatty acids (NEFA’s) (mmol/litre) | <0.4 | <0.7 | A short-term (over the previous two weeks) indicator of energy supplied from body fat mobilisation, which occurs when cows are in negative energy balance. This can occur when energy intakes are insufficient to meet requirements for maintenance, growth, pregnancy and lactation. |
| Urea (mmol/litre) (urea – N x 2.14) | 1.7-3.5 3.6-7.5 | 1.7-3.5 3.6-7.5 | Assesses protein intake and utilisation in the rumen, and whether there is sufficient Effective Rumen Degradable Protein in the ration for adequate rumen function. |
| Albumin (g/litre) | >30 | >30 | Low levels suggest poor liver function, poor long-term protein status or a disease issue such as liver fluke or Johne’s Disease. |
| Globulin (g/litre) | <50 | <50 | High levels indicate a chronic inflammatory condition such as mastitis or lameness |
Minerals:
| Blood parameters | Optimum levels | What it means? |
|---|---|---|
| Pre and post calving | ||
| Magnesium (mmol/litre) | 0.8-1.3 | The mineral element most often deficient in suckler cows over the calving period. Important for calcium mobilisation at calving to help maintain muscle function, reducing the risk of slow calvings, retained foetal membranes and milk fever, as well as hypomagnesaemia (staggers) during lactation. |
| Phosphorous (mmol/litre) | 1.4-2.5 | An important major mineral for bodily functions and energy metabolism. |
| Copper (µmol/litre) | 9.4 -19.0 | Important role in health, fertility and immunity. Blood levels tend to be relatively constant unless excessive overfeeding or underfeeding. Liver copper analysis will give a more accurate indicator of copper status. |
| GSHPx (Selenium) (units/gm Hb) | >50 | Indicates the selenium status of the animals over the past few months. Optimum value varies between laboratories due to different methods used. |
| Thyroxine T4 (nmol/litre) | >20 | Reflects iodine status in late pregnancy. Can be useful in stillbirth investigation. Affected by metabolic rate and time after calving. |
| Plasma Inorganic Iodine (PII) (µg/l) | 50 -105 | Reflects short-term iodine intakes in the previous 24 hours. Expensive test, and so pooled samples often used for group status. |
Source: https://www.sruc.ac.uk/media/hwkf4ryd/tn-745-metabolic-profiling-in-the-suckler-herd-457364.pdf
Interpretation of results for sucklers
The targets for metabolic profiles are applicable suckler cows pre- and post- calving, however some consideration is required when interpreting results. For example:
Cows above condition score 3.5 that have been rationed to lose condition:
- In rations that energy has been restricted this will be reflected in their blood parameters for non-esterified fatty acids (NEFA’s) and Urea/Urea -N.
- It usually takes 7-10 days (can be up to 2 weeks) to correct BOHB’s and NEFA’s.
- By one month pre-calving the calf’s nutrient demand increases, and the cow also starts to produce colostrum in the last 2 weeks of pregnancy. Therefore, in the last month of pregnancy the aim is to maintain body condition.
Outwintered cows:
- Body condition should be closely monitored, if blood parameters for energy appear out with the optimal levels, they may be mobilising more of their body reserves then rationed for.
- Depending on weather conditions outwintering increases energy requirements by up to 15%, ensure feed allocation allows for this.
- Forage crops such as brassicas require careful mineral supplementation, therefore if blood parameters for minerals are out-with optimal levels then review supplementation with your vet/nutritionist and take corrective action if necessary.
- More information on outwintering and troubleshooting can be found here: https://www.sruc.ac.uk/media/ionjjj3r/outwintering-strategies-booklet-497866-sep-2022.pdf
Cows grazing kale for example have a higher requirement for iodine, therefore blood testing is a good indication of mineral status
Conclusion
Body condition scoring is an important management tool, that can be used to monitor and assess the nutrition of the suckler herd at key times. Achieving target body condition score at calving is a key element to accomplishing as close to a 365-day calving interval as possible, and will go a long way to help enhance performance and fertility in the beef herd. Ration formulation is a necessary step that can seem complicated, but when a team approach is taken this will help with planning, and improve the overall productivity of the herd. Metabolic profiling is a useful management tool to assess the nutritional status of the herd and allow fine-tuning of the rations. Alongside body condition scoring and ration formulation it provides a useful insight to the adequacy of a ration and allows for accurate nutritional planning of the suckler herd.
Mary Young, SAC Consulting
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