Healthy heifers
Replacement heifers are the future of your herd. Their health and nutrition need to be carefully managed to ensure they reach their target weights, get in calf and have a successful life in the herd. If heifers are too light at their first mating, they will calve late, be in poorer condition at calving, produce less and their fertility at the subsequent mating will be reduced.
Monitoring growth rates is key to determining the success of any heifer-rearing programme. Target liveweights at different ages need to be set for each individual farm. This can be calculated by weighing adult cows in April or May or by using Liveweight Breeding Values. Heifers should then be at 30% of their mature liveweight at 6 months of age, 60% at 15 months (mating) and 90% at 22 months (pre-calving).
Target weights are only reached when heifers are consistently well fed on high-quality feed from weaning until calving. If low-quality feed is offered, the heifers must eat more to gain the required energy for target growth. However, heifers can physically only eat a certain amount of dry matter per day - approximately 3% of their bodyweight. This means that often heifers cannot consume enough to grow to targets when feed quality is poor. It is very important to consider the quality, or energy content, of the pasture and not just the amount being fed. As the plant matures beyond the three-leaf stage, the cell-wall (fibre) content increases, and the digestibility declines.
Inadequate nutrition is the primary reason heifers fail to reach their target weight. Illness however, both clinical and subclinical, can also have a significant effect on growth.
Gastrointestinal worms are the most common non-nutrition reason for failure to gain weight and ill-thrift in young stock. The optimal parasite management plan will vary between farms but most calves will need regular drenching from weaning until 15 months of age with a combination oral or pour-on drench. Carrying out regular faecal egg counts will determine the need for drenching and probably reduce overall drench use. The same paddocks on dairy farms are often grazed by calves year after year allowing worm numbers to accumulate. Alternatively grazing these paddocks with other stock classes will help reduce the worm burden. Drench resistance is present on some dairy properties. Carrying out a faecal egg count reduction test is a good way of assessing what drench families will be most effective on your farm. Totally Vets offers this service.
Bovine Viral Diarrhoea (BVD) virus causes scours and ill-thrift similar to those caused by parasites, but calves may also have ulcers in the lips and mouth. The virus suppresses the immune system, making calves more susceptible to other diseases such as pneumonia and yersiniosis. Recent testing by Totally Vets has shown a high incidence of BVD in our region. Outbreaks of BVD in weaners can be a recurrent problem on some properties with devastating effects. Very good tests and vaccines are now available.
Facial eczema can have devastating effects on mobs of calves. Don't forget this group in your facial eczema prevention plan. Many other diseases can affect heifers including clostridial diseases, polio, ryegrass staggers, coccidiosis, yersiniosis, pneumonia, bloat, pink-eye and Infectious Bovine Rhinotracheitis (IBR). Most of the diseases that occur in weaned cattle will be prevented by achieving target growth rates.
Visual assessment of heifers is very important to ensure problems are picked up early. Do they look well? Are there dirty tails? Coughing? Poor coats? Weepy eyes? Snotty noses? Are they bright and alert or listless and dull? Do they have a nice bell-shaped abdomen or are they slab-sided?
Keep a close eye on your heifers and give them the best chance.
