by Melissa Goldade

Now that the heifers are home from the summer and fall pastures, it is time to prepare them for their winter diets. There are many factors that should be considered when formulating a heifer ration and feeding heifers all year long.

Eliminate parasites
Parasites can be one of the largest negatives for a heifer program. This includes both external and internal parasites. Parasites can greatly reduce feed efficiency and result in reduced growth. A 10% increase in maintenance energy requirements may be needed for heifers with a high number of internal parasites, greatly increasing feed costs.

It is recommended to deworm heifers and cows every fall and spring, especially if they are coming off, or going onto pasture. Some sources even recommend deworming three times per year.

Parasites survive on all types of winter pasture conditions and therefore all pastures that have been grazed the previous year are considered infected. That is why spring treatment of replacement heifers is recommended to reduce infection and prevent further contamination of the pasture. The first treatment should be at the start of the spring grazing season followed three to five weeks later with the second treatment. The third treatment should come three to four weeks after the second or when the animals are brought home from pasture.

The most common external parasites that attack cattle over the winter are lice and barn mange. Both of these can be easily eliminated by using a delouser such as Ivomec®. Consult your veterinarian about which product would work best in your herd.

Cold stress
If heifers are housed inside, with clean dry bedding at all times, and have no manure on them, they will not experience cold stress over the winter and spring. However, not all producers have the facilities or abilities to house heifers this way and therefore must adjust the ration for cold stress.

Cold stress includes a number of factors, such as temperature, animal size, wind, and insulation capacity of the animal. Animal size is important because larger replacement heifers are less sensitive to cold stress than smaller heifers. Exposure to wind also increases heat loss. The most common cause of cold stress is destruction of the insulation ability of the hair coat by snow, rain, mud, or manure.

According to Pat Hoffman, University of Wisconsin, the net energy of maintenance for replacement heifers should be adjusted for cold stress. At minimum, it should be adjusted for conditions where hair coat insulation is poor (wet or muddy). Net energy of maintenance requirements rise dramatically for heifers with heavily mud-laden hair when temperatures fall below 14º F for 900 pound heifers and 5º F for 1200 pound heifers.

Other factors affecting nutrient requirements
In addition to parasites, housing and cold stress, there are a variety of other factors that need to be considered when formulating heifer rations during the cold months.

Body condition of your heifers is a factor that should not be overlooked. If heifers go into the cold months with a low body condition score, and the ration is not adjusted for cold stress, parasites or other factors, the heifers could be very thin by springtime. This is an even bigger concern if they are losing weight before calving. It is recommended to have heifers at the body condition score of three to three and a quarter and to adjust the ration for gain in addition to the increase in maintenance energy for cold stress. Heifers should gain one and a half to two pounds per day throughout their rearing.

The use of ionophores for replacement heifers has increased over the past several years. By increasing feed efficiency, ionophores in the winter diet may help reduce the amount of extra feed needed to help combat cold stress. ANC Heifer Base contains the ionophore, Rumensin®, and we have seen beneficial results in growth. It is recommend to use Heifer Base in all heifer rations.

Winter and cold, wet springs seem to bring on an increase in diseases such as pneumonia. Many producers find it helpful to feed products such as Auroemycin crumbles to help fight respiratory problems before they begin. Consult your veterinarian about your particular situation.

It is important in all seasons to make sure there is more than adequate bunk space for all animals to eat and that water is readily available.

Keep your consultant informed
One of the most important parts of formulating a heifer ration is keeping your consultant informed of any type of enviromental or managerial situations that should be factored into the ration. That way, the ration analysts can adjust for cold stress, poor body condition score, outdoor or indoor housing, and ionophores.

Remember, the more informed your consultant is, the more we can fine tune your ration to ensure optimal heifer growth. This includes not only getting her in the milking string at 24 months of age, but also having her growthy and in good condition so she is ready to make a good record for you.

Economic impact
Studies show that it cost a producer $1.50 to $3 per heifer every day that calving is delayed beyond 24 month. The results of this delay for a 50 cow operation is a per year forfeiture of $4,500 to $9,000 of profits by calving heifers at the current Wisconsin average of 28 months versus 24 months. This does not include the additional losses due to veterinarian bills and milk loss associated with calving heifers in too small due to poor growth.

Don't let the winter slow the growth of your heifers due to cold stress, parasites, or other negative factors. Keep your heifers growing all year long by checking your heifers growth with published growth charts and adjusting the ration to fit the current situation. Your consultant has these growth charts available for you which considers both height and weight for proper growth.

Let ANC help you increase your profitability by implementing a good heifer program that will give you healthy, growthy heifers ready to produce at 24 months!