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Breeding Season Fast Approaching on many Farms

23 April 2018
Type Media Article

By John Kilboyle, Teagasc Adviser, Galway/Clare Regional Unit

After a long winter, the breeding season is only around the corner. The last few weeks have been very busy on farms, dealing with cows calving and the challenges of fodder shortages in many areas. It is important to keep focused on the upcoming breeding season. Setting realistic breeding targets for your farm is the key starting point in developing a plan and managing your herd throughout the breeding season. The overall breeding targets to aim for include;

  • An average calving interval of 365 days
  • 0.95 calves born per cow to the bull
  • 60% of cows calved in the first month of the calving season
  • All cows calved within 12 weeks
  • Calf mortality <2.5% at birth and < 5% at 28days

Factors influencing breeding performance on farms:  

Cows Body Condition Score

  • Targets; Condition score at calving needs be a herd average of 3.0 for spring calvers; this allows for 0.5 of a B.C.S loss up to start of breeding season. At the start of the breeding season a cow needs to be on an increasing plain of nutrition with a BCS of 2.5 to give her the best possible chance of going back in calf.
  • Thin Cows; Cows/ Heifers calving in poor condition and or losing excessive weight post-calving will have a delayed return to heat. At this stage; feeding on its own may not solve the problem with thin cows/heifers. In all cases, thin Cows/ heifers will require 1 to 2kg of a high energy, 16% Crude Protein ration per day until there is adequate grass. However, in addition to feeding, If possible restricted suckling of calves in the morning and evening (from 4 weeks of age) will help break the maternal bond between cow and calf. This practise helps improve cow’s/ Heifers body condition coming into the breeding season and cows will return to heat cycle quicker.

Having a Defined Breeding Season - Aim to have all cows calved in a 12 week period, i.e. 60% in the first month, 80% calved by end of second month. Cull very late calvers, replace with young cows or heifers. Have a definite start/end date for the breeding season. For example, a farmer with five month calving spread that has an ultimate target of a three month calving spread for the herd, a simple means of achieving this is to end the breeding season two weeks sooner each year for the next four years.

Calving Difficulty

Difficult calving greatly increases the incidence of reproductive problems in the following breeding season and also reduces calf survival. When selecting sires, a good rule of thumb is to use bulls that are < 5% calving difficulty and high reliability on heifers and < 10% calving difficulty on mature cows. The higher the reliability of a bull the more proven that bull is hence the more confident you can be in his figures.  

Health Issues Affecting Fertility

Any issues with herd health need to be checked out fully in consultation with your vet in advance of the breeding season. Uterine infections can significantly delay the onset of cycling. All abortions and stillbirths should be investigated by a vet.

Replacement Heifers: 

Calving at 24 months will have a huge impact on the heifer’s lifetime performance in your herd.. These heifers need to be 60% of mature weight at breeding (i.e. 360- 420 kg’s for mature cow 600 – 700 kg’s). Replacement heifers need to calve at the start of the calving season to an easy-calving bull of less than 5% calving difficulty with a high reliability. As 1st calvers, these animals will need preferential feeding (1-2 kg’s 16% high energy ration) vs. mature cows up to turnout to grass to ensure return to heat cycle and maintain a 365 day calving interval.

Stock Bulls Key Points:

Bull fertility is key to maintaining a compact calving period, maximising the genetic potential and value of the calf crop and overall herd profitability.

  • Bulls fertility status can change, from year to year therefore, it is good practise to have a fertility test carried out on the stock bull, prior to start of breeding season
  • Bulls must be able to maintain body condition score (ideally BCS 3), repeatedly mount and serve cows and place fertile semen in the cow for 12 weeks and have a long working life in the herd.
  • Avoid sudden changes and do not overfeed as this can reduce fertility and lead to feet problems.
  • Check feet and legs well in advance of the breeding season, take remedial action if required.
  • Watch the bull working to check he is serving cows correctly.
  • Rotate bulls or scan cows early so that an infertile bull or sub fertile bull can be identified early.
  • Record when you see a cow being mated and watch for signs of cows coming on heat repeatedly.