Herd Health and Vitality is Essential at Breeding Time
Type Media Article
By Anthony O'Connor, Teagasc Adviser, Galway/Clare Region
Herd health and vitality are hugely important in the run up to the breeding season. Both are key components to achieving breeding targets such as;
- An average calving interval of about 365 days
- 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 of 2% at birth and 3% up to 28 days
Achieving these targets depends on a high level of herd management and herd health. Any herd health problem needs to be checked out fully in consultation with your Vet.
The main factors that influence fertility are:
Calving Difficulty - Conception rates are reduced following difficult calvings. Conception rates can be reduced by 50% by very difficult calvings compared to normal unassisted calvings. Calving difficulty is primarily influenced by calf birth weight (mainly attributable to the sire) and by cow condition and pelvic size. To avoid excessive calving difficulty, choose sires to suit the cows in your herd. If involved in Herdplus, view all available data from ICBF on calving difficulty for your herd.
Calving Spread - Aim to have all cows calved in a three month 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. Restricted suckling will encourage late calvers back into heat.
Diseases and Mineral Imbalances - diseases such as Leptospirosis and BVD, uterine infections and mineral deficiencies. Vaccinations to control these diseases and injections to correct deficiencies need to be given well in advance of start of the breeding season. Likewise, all breeding stock needs to be free of parasites.
Cow Body Condition Score - Condition score at calving needs be a herd average of 2.5 for spring calvers. Early calving cows will lose condition after calving while indoors but should regain condition quickly on going to grass. They must be at least 2.0 at mating and gaining weight. Excessive weight loss post-calving will delay return to heat. First calvers lose more weight after calving than mature cows and are also slower to gain weight at grass. They will require 1 to 2kg of a high energy, 18% Crude Protein ration per day until there is adequate grass. Stomach worms can also be a problem, so a worm dose now could be beneficial.
These are the future of your herd, handle carefully. Many progressive suckler farmers breed replacements at 15 or 16 months of age. To achieve this, replacements heifers should be from your own herd, be robust and well developed, free of parasites, weighing 65 to 70% of mature body weight at mating. These homebred heifers need to be bred to an easy-calving non-continental bull of less than 4% calving difficulty. Early turnout to grass and good stockmanship will help achieve this. Any purchased replacements must be from a known, disease free source.
A bull is half a herd, a vital half. It is estimated that 3%-4% of bulls are infertile and a further 15%-20% are partially or periodically infertile. After turning out the bull, record the dates of the first matings and check for repeats 18 to 23 days later. A high number of cows showing repeat heat are a sure sign of bull infertility. Never assume full fertility in a bull because he was satisfactory last year. All hoof problems should be treated well in advance of the breeding season. Bulls that were sick and had a high temperature are likely to have impaired fertility at 6-8 weeks later.
In summary, your bull needs to have a strong libido, firm testicles with a high fertile sperm count. Scrotum area free of sores, cuts and bruises. Also, legs and hooves (especially hind legs) must be firm and sturdy, to enable bull to stand up to the job.