This is a subscriber-only article
Rearing replacement heifers is one of the most important aspects of herd management. Retaining heifers as replacements will determine how productive the breeding herd will be in years to come.
Replacement heifers should reflect the best maternal genetics available, not just the most visually pleasing animals.
One of the main downfalls in getting heifers to calve down at 24 months of age, and go back in-calf, is having animals well developed before they go to the bull for the first time.
The first winter period is crucial for getting sufficient weight on to heifers before the breeding period next summer.
Outlined are some tips to managing potential replacement heifers over winter.
Weigh heifers regularly to monitor weight gain
Start off by weighing heifers at housing to determine their actual weight, not an estimated weight. Weighing heifers every six weeks allows you to keep on top of performance throughout winter.
Ideally, a heifer should be going to the bull next May, or June, at 400kg to 450kg liveweight. If the animal is housed at 280kg on 1 November, this means the heifer has to gain 120kg to 170kg over the next 190 to 200 days.
This works out at a daily weight gain of 0.65kg to 0.85kg/day from housing to breeding. It doesn’t seem like an excessive target, but many heifers fail to hit these weight gains during the housing period.
Weighing will indicate if silage and concentrate feeding is adequate, and will also highlight if housing and feeding space is sufficient.
Weighing heifer calves at housing will also give a good indication of which cows have greater milking ability.
Ideally, heifer calves bred from these animals should be marked as potential heifer replacements.
Look back through calving records
Rather than simply choosing heifers based on their physical appearance and liveweight, you should also take a look back through herd records.
Identify the cows from which potential replacements were bred. Do these cows calve down at the same time every year, or are they slipping in calving date?
Cows calving at the same time every year will be more fertile. Fertility is a highly heritable trait. Cows slipping in calving date will be less fertile.
Also, identify cows which repeatedly have problems at calving time. For example, did the cow open properly at calving, or did the animal have a dangerous temperament at calving?
Frame and feet
Are potential replacements well developed in terms of frame and walking correctly? Ideally, heifers will have moderate to good body size, along with width in the hind quarter.
While there is nothing wrong in selecting heifers with good conformation, avoid animals with excessive muscling at the hind quarter.
Run replacement heifers as a separate group
Pick out replacement heifers now and run them as a separate group this winter. Do not be tempted to let all animals run together for easier management, then rush into selecting heifers next spring at the start of the breeding period.
Having heifers separated now will allow animals to get priority feeding and management. It also makes these animals much easier to weigh every month.
Winter diet
Feed heifers good-quality silage and concentrates to maintain a daily weight gain of 0.7kg to 0.8kg/day over winter.
Target 70DMD silage and 1.5kg/day of concentrates. For silage at 67DMD to 70DMD, increase concentrates to 2kg/day.
Avoid feeding silage below 67DMD to heifers, as weight gain will be reduced. Feeding higher levels of concentrates on low-quality silage will only cause animals to become overfat, rather than supporting higher weight gain. It is also increases feed costs.
SHARING OPTIONS: