Thin cows require more feed over the winter

Do thin cows have more difficulty making it through the winter?
Thin cows have less fat cover than cows in good condition. Fat is a good insulator, which in turn helps reduce energy requirements to keep the animal warm. An additional 1200 to 1400 pounds of hay is needed to feed a thin cow (condition score 2) versus a cow in good condition (score 3) through the winter. Lower critical temperatures – the point where a cow requires to generate heat from feed consumed to keep warm – is more of a concern with a thin cow. Thin animals cannot tolerate the cold as well as cows in good condition.

How much more feed is needed to get the cow into good condition prior to winter? 
Amount of feed required to bring the cow back in to good condition depends on how thin the cow is and stage of production. Reduce energy requirements of the cow as much as possible. If the calf is not weaned, do this as soon as possible. Provide good to high quality forage (with high-energy content). Eliminate straw from the ration. Supplying grain in the ration increases total energy intake and thus improves rate of gain. Getting a cow to improve condition score from a 2 to a 3 requires 200 pounds of gain. With a 6 to 1 feed conversion ratio, 1200 pounds of additional feed may be needed to gain the required amount of weight. It is easier to have animals gain weight prior to the start of cold weather.

Work completed at the Ellerslie Test Station (Yurchak, 2003) has determined that feeding costs for a thin cow are anywhere from $0.42 to $0.85 cents per day higher than for a cow in good condition. Over a 200-day feeding period, this relates to $82.00 to $170.00 difference in feeding costs alone.

Will the thin cow milk as well as a cow in good condition?
Thin cows are not able to milk as well as cows in good condition. When cows mobilize fat off of their frame, one pound of fat provides enough energy to produce 7 pounds of milk. Lower milk production results in lower weight gains and thus in lighter weight calves for sale in the fall.

Will a thin cow have more problems getting "into calf" next year?
Thin cows take up to 20 days longer to show first estrous after calving than those in good condition. First service conception rates are also 20 % lower for thin cows.

Thin cows tend to have more problems with calving. Animals requiring assistance with calving typically have more difficulties getting into calf during breeding season.

Feeding management over the winter is also critical to get cows rebred the following breeding season. When cows lose large amounts of weight over winter, (drop from condition score 3.0 to 2.0) a 30 to 35% smaller calf crop can be expected the following year.

Will calves from thin cows have more health problems?
The amount of colostrum and quality of colostrum from thin cows is lower than for cows in good condition. Calves receive less immunoglobulins IGA (short term immunity) and IGG (long term immunity) tend to have more illness compared to calves born from cows that are in good condition.

How to develop a balanced ration to meet requirements.

Get assistance from various specialists (nutritionists - either private or those working for a feed company or an extension specialist). Using a feed balancing program such as CowBytes can assist producers to develop rations at the kitchen table.

Effects of nutrition on beef cow reproduction
Body condition: implications for managing beef cows
Beef cow body condition management
Working with your Consulting Nutritionist/Feedmill