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:
If this does not sound like your herd, YOU could become more PROFITABLE!
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%|
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.
Fertility is directly affected by cow body condition score. Some top tips to promote fertility through nutritional management can be seen below:
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|
|Mid pregnancy (weaning)||2.5||3.5 to 4|
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%|
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)|
(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)|
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