Improving Key Performance Indicators: Breeding Herd

Farrowing rate, farrowing index and non-productive days are interconnected and important key performance indicators for the breeding herd. BPEX explains why in number 26 in its series Action for Productivity.
calendar icon 2 December 2009
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Achieving a consistent flow of sows and litters through the farrowing and subsequent departments is paramount to the smooth operation of the unit. It is important to keep the cost of producing piglets to a minimum to enable you to maximise profitability at sale. Knowing how your breeding herd performs helps you to identify where and how to concentrate your time, effort and investment to improve performance and reduce the cost of production.


  • Farrowing rate: aim for 88+ per cent
  • Farrowing index (litters per sow per year): aim for 2.4
  • Non-productive days: aim for 15 or fewer

Based on top 10 per cent national figures 2009

Keeping track of changes in performance over time means you learn what works for your unit, in terms of herd management and environment, motivating you and the team to do more of this. It also provides early warning if performance starts to deteriorate.

Farrowing Rate

Fertility chart from Agosoft
  • The farrowing rate tells you the number of sows that farrow as a percentage of the number of sows and gilts that are served.

  • A farrowing rate of 85 per cent means that for every 100 sows and gilts served, 85 have gone on to farrow, whilst the remaining 15 have either returned, been culled or died.

  • To calculate farrowing rate, keep a record of all sows and gilts served and all farrowings over a 12-month period. Divide the number of sows farrowed over 12 months by the number of sows and gilts served and multiply the answer by 100.

  • You can track changes each month by deleting data from the earliest month and adding data from the latest month.

Farrowing rate can then be compared with industry averages:

Average Top third Top 10%
Farrowing rates (%) 80.0 84.0 87.5
Farrowing rate
Source:Agrosoft Ltd
  • For a ‘real time’ farrowing rate record, draw up a fertility chart and record weekly services, subsequent failures and expected percentage farrowing rate.

  • Incidences of high numbers of returns, irregular returns and late returns are then recorded and monitored weekly and quick corrective action can be taken as required.
  • A low farrowing rate indicates a need to improve herd management:
    • sow and gilt management – stable body condition, social environment etc
    • nutrition and feeding regimes
    • stockmanship, including heat observation and recording, service/AI management and handling techniques
    • physical environment, including the thermal environment and hygiene, and
    • timeliness of decisions regarding culling sows.

  • The farrowing rate provides a guide to how many sows you need to serve to run the farrowing accommodation at optimum capacity, which is key to achieving competitive financial performance.

  • One crate or 10 less piglets weaned per week would accumulate to a projected net margin loss of £10,000 over the year (based on figures from BPEX Pig Yearbook 2009).

  • If the farrowing accommodation provides capacity for 16 sows to farrow each week and the farrowing rate is 85 per cent, you need to serve 19 sows to fill each farrowing room each week. However, if the farrowing rate falls to 75 per cent, you need to increase services to 21 sows and gilts per week.

  • Some managers routinely serve higher than the number theoretically required to ensure a full farrowing house; excess sows are then culled once the batch has been confirmed in-pig.

  • You need to think through the implications of any new practices carefully. For example, you need to make sure that any increase in sows served – to overcome a low farrowing rate – does not lead to overcrowding of the sow accommodation.

  • You also need to be aware of costs: extra feed, AI, straw and labour. Each extra sow served and housed through to seven weeks post-service costs approximately £30 per sow. If, on a 350 sow-herd, an additional 15 per cent of sows are served each week (two or three animals), the additional cost would be around £3,500 per year.

Farrowing Index

Farrowing index, also referred to as litters per sow per year tells us the average number of times sows farrow in a year. The average farrowing index for UK herds is 2.25; the best herds achieve nearer 2.39. Examples of the effect different farrowing indexes have on herd production:

  • 350 sows with a farrowing index of 2.25, weaning 10 pigs, wean a total of 7,875 pigs per year

  • Improving the farrowing index to 2.39 would wean 8,365 pigs per year (a six per cent increase) worth £10,000 for a typical 350-sow herd based costs and prices reported in the BPEX Pig Yearbook 2009

  • Alternatively, you could wean 7,875 pigs from just 329 sows (six per cen fewer sows) taking pressure off the service and dry sow accommodation and reducing dry sow feed, variable and labour costs.

Farrowing rate can then be compared with industry averages:

Number of sows Piglets weaned/litter Farrowing Index Piglets weaned per year Benefits
350 10 2.25 7,875
350 10 2.39 8,366 +£10,000
329 10 2.39 7,875 Reduced pressure on accommodation and reduced dry sow feed, variable and labour costs.
Source:Agrosoft Ltd

Computerised individual and herd recording will provide regular updates on farrowing index. In the absence of a computerised system you can get a broad idea of farrowing index by completing Table 1.

Table 1. Farrowing index calculations
Example Your herd Industry average Industry top 10%
(A) Record the number of farrowings over 12 months 770
(B) Do a stocktake of sows and in-pig gilts (included from date of first service) each month over 12 months and calculate the average. (This will only work for a stable herd size) 350
Calculate farrowing index by dividing number of farrowings by the average number sows and in-pig gilts (A ÷ B) 770/350
= 2.2
2.25 2.39
Once you have your first 12 months data, you can track changes each month by deleting data from the earliest month and adding data from the latest month.

Farrowing index is determined by four key factors:

  • Length of pregnancy (usually 115 but can be up to 117 days)
  • Length of lactation (typically 26 to 27 days)
  • Typical number of days healthy sows take to come into heat following weaning (about six days)
  • Non-productive days

There is little you can do to change the first three – other than making a radical change to your system, e.g. weaning age or herd genetics.

Non-Productive Days

To improve your farrowing index concentrate on non-productive days, These can be caused by:

  • Delayed heat after weaning – perhaps because the sow is in poor condition, or housing design does not give weaned sows good exposure to the boar
  • Sows missing a service – which might be due to poor heat observation or sows coming into heat in the farrowing house
  • Sows returning – potentially due to timing of service or an inadequate environment
  • Delayed returns – these are late returns or returns, which go undetected until the seven-week scan or even further into the planned pregnancy
  • Sows culled or dying during pregnancy – due to lameness, for example.

In recording terms, non-productive days can also increase due to constructive management decisions taken to improve herd productivity and/or resource utilisation. For example, using nurse sows (either intended cull sows or extending the lactation of a breeding sow) or over-serving to ensure full utilisation of the farrowing house, with excess sows culled once pregnancy is confirmed. It is important to understand the impact of these on your farrowing index.

To improve farrowing index you first need to investigate reasons for non-productive days and determine what you can do to reduce these. An individual sow recording system will provide the most accurate measure of total nonproductive days and will highlight where these are occurring. In the absence of an individual or whole herd recording system, complete Table 2 to provide an idea of lost days on your unit and how your herd compares with industry average:

Table 2. Non-productive days
Example average herd Example top 10% herd Your herd
(A) Estimated gestation period 115 days 115 days
(B) Estimated length of lactation* 27 days 27 days
(C) Typical weaning to service interval 6 days 6 days
(D) Total productive days per cycle (= A+B+C) 148 days 148 days
(E) Farrowing index 2.25 2.39
(F) Multiply total productive days per cycle (D) by your farrowing index (E) 333 days 354 days
(G) Subtract from 365 days (365-F) to calculate your non productive days 32 days 11 days
*Note: the legal minimum weaning age is 28 days. However under certain conditions, such as adoption of rigorous biosecurity measures, piglets may be weaned at a younger age.

To explore the situation further, you will need to keep a record of what is happening with individual sows. Here is an idea of how individual factors can impact on lost days.

Approximate additional lost days per year Assuming each lost day per annum costs £1.50/sow in lost net revenue (BPEX PigYearbook 2009)
An additional 15% of sows served return at 3 weeks 7 days £10.5 per sow/annum
5% of all sows arriving at the farrowing house are found to be not-in-pig 13 days £19.50 per sow/annum


  • Farrowing rate, farrowing index and non-productive days are all interconnected. Actions you take to improve farrowing rate have the potential to also reduce non-productive days and improve farrowing index.

  • To improve sow performance, identify where there is greatest potential for improvement on your unit by comparing your performance with industry data. Set yourself achievable targets and then determine the most cost-effective ways to achieve these targets.

  • Detailed financial data for the unit will enable you to go one stage further in prioritising between alternative management changes, with a ‘what if’ assessment enabling you to assess the financial benefits of improving performance on your unit.

  • On-going recording of sow performance will tell you how successful the measures you are taking are and provide encouragement to you and your team to do more of the same.

December 2009
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