Katie Grantham one of our Sales Team explains how you can Maximise the Fertility of your Beef Suckler Herd

A look into how you can improve your herd fertility.

The profitability of any suckler herd relies on calf output, which is directly affected by herd fertility.  Research has shown that fertility is five times more important than growth rate and ten times more important than carcass quality. This is due to the high costs poor fertility can incur through:

·      Increased labour ·      Reduced calf output
·      Production losses ·      Poorer weaning weights
·      Higher culling rates ·      Increased calf health problems
·      Reduced sales value of calves that are not uniform

Targets to aim for are:

  • ·      Bulling period – nine weeks for cows and six weeks for heifers
  • ·      95% conception rate
  • ·      Calving 65%+ of the group in the first three weeks
  • ·      Aim for 90% calving in six weeks
  • ·      Calf mortality from birth to weaning should be less than 3%
  • ·      Aim for 94% calves reared to animals bulled
  • ·      Replacement rate should be less than 15%

If this does not sound like your herd, YOU could become more PROFITABLE!

Heifer Management

When selecting breeding heifers some key traits to select for are:

·        Dams with good longevity ·        Meet target bulling weight
·        Good history of regular fertility ·        Quiet temperament
·        Select daughters of dams that calve early ·        Good health and good udder records

Growth targets for heifers can be seen below, if growth targets are not been met fertility can be impaired.

  15 months 24 months 36 months Mature
% of mature weight 65% 85% 95% 100%
Target weights 422kg 552kg 617kg 650kg

(Fuller, 2018)

Heifers should be bred for a six-week period. If they do not hold in-calf after two cycles they may be sub-fertile and should be removed from the herd.

Due to heifers having a greater energy requirement in comparison to cows, they should be managed separately for the first two years after calving. Heifers require a higher plane of nutrition, as whilst they are producing milk for a calf and returning to oestrus they are also continuing to grow and maintaining their body condition score. If not kept separate, heifers may be at a disadvantage from competition for food from more dominant herd members.

Herd Management
  • ·      To ensure fertility isn’t impaired across your herd, cattle health must be monitored. Infectious diseases and impaired mobility of cattle can have devastating effects on fertility.
  • ·      Consider a herd health plan. A comprehensive vaccination programme can be a cost saving method of protecting your herd against infertility.
  • ·      If any of your herd have feet or leg problems, it will reduce mobility and libido, reducing successful mating.
  • ·      Bulls need semen testing before the mating season, this will identify sub or infertile bulls therefore reducing the risk of extending your calving interval

Fertility is directly affected by cow body condition score. Some top tips to promote fertility through nutritional management can be seen below:

  • ·      Silage quality should be monitored as variations occur annually.
  • ·      Outwintered cattle may have a higher energy/protein requirement particularly if they are in poor body condition at housing.
  • ·      Cows should be on a rising plane of nutrition six weeks prior to bulling to promote oestrus/fertility.
  • ·      Yearling bulls scrotal size increase by 1cm every month between 10-14 months if under good nutrition, making this a critical time to promote lifelong fertility.
  • ·      Mineral deficiencies on occasion cause infertility. Certain geographical areas have deficiencies in trace elements. Bolus’s containing trace elements can be a solution to this, however, consult your vet prior administration, if not required, then it can be costly and have negative effects on fertility.
  • ·      Winter rations should always contain a mineral and vitamin supplement to cover any potential deficiencies. Straw-based rations require supplementation with selenium and vitamin E.


The body condition score of cattle is crucial in promoting good fertility, targets to aim for depending on your calving pattern can be seen below:


 Target body condition score
Stage of reproductive cycle Autumn calving Spring calving
Calving 3.5 2.5
Mating 3 3
Mid pregnancy (weaning) 2.5 3.5 to 4

(Fuller, 2018)


Hybrid vigour is an effective way to increase the production of your suckler herd. All commercial beef herd should use crossbred cows, as they perform more efficiently than pure-bred cows. Cross-bred cattle have higher levels of fertility than pure-bred animals, improving your chances of successful breeding. They also remain in the herd 1.3 years longer and have a 30 percent greater production output compared to pure-breds. Hybrid vigour improves low heritability traits such as fertility, calf viability and cow longevity. Research has found that crossbreeding can achieve a 25% increase in total calf weaning weight compared with the average performance of pure-bred breeds that make up the cross bred.

Hybrid vigour can be split into three phases. The USDA Meat Animal Research Centre (MARC) in Nebraska have shown the following advantaged of crossbred cows over pure cows.

Advantages of crossbred cows compared to pure bred
·      Number of cows weaning calves  + 7%
·      Weight of calves at weaning  + 5%
Effect of third breed terminal sire
·      Calves weaned  – 4%
·      Weaning weight  + 8%
Advantages of crossbred calves
·       Number weaned + 3%
·      Weight at weaning + 6%
Total advantage due to hybrid vigour + 25%

(Fuller, 2018)

Scrotal circumference is an accurate predictor of fertility in young bulls, as well as the future sperm producing characteristic of the testes. An increase in scrotal size is linked to increased sperm mobility, increased normal mobility and a decrease in abnormal sperm. Scrotal circumference is a highly heritable trait (50%) and should be measured between 400 and 500 days of age to get an accurate measurement. If a breed needs to increase their average scrotal size it would be relatively easy to achieve.

Using a bull with a scrotal circumference which is 2 cm over the breed average would increase progeny’s scrotal circumference by 1 cm. Testes size does not only improve male fertility but also reduces the age females reach puberty, a 2 cm larger scrotal circumference compared to the breed average should reduce heifer puberty by up to 7 days, depending on nutrition.

Breed  Heifer age at puberty (days) Scrotal circumference of yearling bulls average (cm) Range (cm)
 Gelbvieh  341  34.8  30-42
 Brown Swiss  347  34.3 31-40
 Red Poll  352 33.5  30-37
Angus 372  32.8 27-38
 Simmental 372  32.8 37-39
 Hereford  390  30.7  37-36
 Charolais  398  30.5  25-38
 Limousin  398  30.2 24-34
 Average  368  32.3

                                                  (Gregory, Cundiff, and Koch, 1999)


The table above demonstrates how the Stabiliser breed has utilised the fertility traits from the Gelbvieh, Angus and Simmental. Although it is not a commonly used breed the Gelbvieh’s high scrotal circumference and the earlier age of heifers at puberty is a highly desirable trait, therefore it was incorporated into the Stabiliser mix. Although the Brown Swiss and Red Poll breeds have high levels of fertility, there is not a large enough gene pool to gather from to produce the ultimate Suckler cow, which the Stabiliser has become.

Another way to manage fertility through genetics is by selecting bulls with low birth-weight EBV’s, this will reduce the incidence of difficult calving, consequently minimising the risk of problems with re-breeding. Cattle which have undergone a difficult calving have been reported to have pregnancy rates reduced by 14% and those that did become pregnant to calve 13 days later at the next calving.


The Effect on Weaning Weights by Reducing Calving Spread from 15 to 9 weeks

Breeding Cycle % Calved Total Wt (kg) % Calved  Total Wt (kg) Weaning Wt (kg)
1st 35 10,500  65 19,500  300
2nd 25 6875  25 6875  275
3rd 17 4250  5 1250  250
4th 13 2925  225
5th 5 1000  200
TOTAL 95% 25,550  95%   27,625

(Fuller, 2018)

Increase in total calf weaning weight                   2,075kg per 100 cows

Value gain of calf crop @ £2.10 per kg                  £4,357 per 100 cows


 On average 35% of bulls give successful service on first attempt, Stabilisers are 65% successful.

It is interesting to see the effect an extended calving period has on weaning weights and therefore total herd output per 100 cows.

However, most herds are weaning 10% lower number of calves per cow mated (85%). This has a huge impact on reducing total calf crop value.

10 missing calves at weaning are worth about another £6,000!

So, added together a well-run Stabiliser herd is earning an extra £10,357 = £103 per cow

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