Many weaned dairy heifers have gone from eating high-quality milk replacer and calf starter in a nice cozy calf barn to being kicked outside in the arctic weather and being fed leftovers from the lactating cows. It’s a shame that many replacement heifers are fed in this way and thus fail to reach their full potential as milk cows. In contrast, dairy heifers that are raised on a good nutrition program that promotes steady good growth have a better chance at making good milk and good profit.
Such economic success is really the result of implementing a good heifer feeding program from three to 24 months of age in replacement dairy heifers. This program is based upon three timeless, yet simple targets:
- Reach 540 to 600 kg at 22-24 months of age at first calving and enter the milk line.
- Reach 380 to 430 kg at 13.5-15 months of age, show strong heats and be ready for first breeding.
- Allow for 800 g of gain per day after they reach puberty until calving.
To attain steady growth, many universities around the world have collectively advised young replacement dairy heifers should consume a palatable diet designed with an energy level of about 65-69 per cent TDN. Some more definitive extension references dictate a dietary metabolizable energy of 2.3 Mcal/kg, diet.
These research and field trial energy values are usually based upon above-freezing temperatures, when little, if any significant metabolic energy is used to keep heifers, warm.
Factor in the cold
In order to make Canadian cold-weather energy adjustments, we should use the guideline of: for every 1 C drop in temperature below 0 C, most cattle TDN energy maintenance requirements increase by about two per cent. That means we should increase the above heifer energy requirements in their diet by 40 to 50 per cent when they are braving -20 to -25 C temperatures (with windchill) in an outside pen.
Unlike dietary energy, protein levels in the same heifer rations are not affected by winter conditions. We often recommend that three- to six-month old animals need a diet of about 16 to 18 per cent protein, while older animals from six months to breeding age need a 15 to 16 per cent diet. When dairy heifers are bred at 14 to 15 months of age, these protein levels can be dropped to 13 to 14 per cent. About three weeks before replacement heifers calve, one should implement a well-balanced 16 to 17 per cent protein transition diet with a similar modest energy level.
How they are fed matters too
No matter what diet is being fed to dairy heifers, it is just as critical as to how diets are fed. Here is an outline of some good rules of dairy heifer bunk management:
- Segregate heifers according to weight and size. The key is to avoid feeding small younger animals with older heavier animals. Bred heifers should be segregated from un-bred ones. As pregnant heifers get closer (re: three weeks before) to calving, they need their own pen and own specialized “transition” ration.
- Check outside feed bunks before the next feeding. If a wintertime bunk is licked clean, it might be good sign to feed more heifer diet, so all energy requirements are met during cold weather. Reduce the amount fed if one has lots of feed refusal.
- Check on your heifers. By nature, they will have a social pecking order. You should be aware of animals that don’t come to the feed bunk. It is important to provide enough initial bunk space and then more eating area when they get older.
- Provide appropriate shelter and windbreaks. Replacement heifers should be able to get out of the direct wind at all times. Wherever windchill is decreased by 5 C, 10 per cent is saved in additional dietary energy spent on keeping heifers warm. Extra clean bedding should be put down on a frequent basis adding insulation against the cold ground.
- Scrape the pens. In above-melting weather, occasionally clean the concrete pad adjacent to the feed bunk. It doesn’t make sense that heifers should be forced to stand in mud, melted water and manure as they are eating.
Feeding and management of dairy replacement heifers should be relatively simple. They have their own brand of nutrient requirements, so they should have their own designated feeding program. Raising them outside in this way should return them to the dairy barn as promising first-calf cows. Given the appropriate milking cow nutrition should turn them into good mature dairy cows for many lactations to come.