It is well documented that a balanced ration provided to a pregnant cow impacts muscle tone and the ability of the cow to deliver the calf. It helps prevent downer cows and milk fevers. The quantity and quality of colostrum produced 4 to 6 weeks prior to calving is also impacted (required for passive immunity passed on to the calf). Lastly, the ability to repair the reproductive system (involution) and prepare for the breeding season is also affected.
The cow is at or near peak lactation when breeding season starts. This stage of production has the highest demands for nutrients over the production year. At very early stages of pregnancy, the placenta develops rapidly. The placenta has many different types of cells, each has a different function. One function is the development of blood vessels which are needed to transfer nutrients from the maternal blood supply to the fetus. If nutrients are not available to fully develop the placenta the growth rate and development of the fetus can be impaired.
By day 21 of pregnancy, a calf heartbeat can be detected. By day 25, the pancreas, liver, adrenal glands, lungs, thyroid, spleen, brain thymus and kidney are starting to develop (Hubbert et. al., 1972). It is critical to provide a balanced ration in early pregnancy. If the nutritional needs are not met, development of these organs can be delayed or growth of these organs can be reduced. The function of these organs can be impaired. Research completed by Long, et.al, (2010) determined that cows that were underfed for the first 83 days of gestation resulted in calves having a smaller lungs and trachea compared to the cows fed the proper ration.
Other research found that early pregnancy nutrient deficiencies can predispose calves to cardiovascular, metabolic and endocrine diseases later in life. It can also cause the fetus to change the production of hormones to ensure its survival in utero, but can impact future growth potential later in life.
Turning cows out early onto last years’ carry over dormant pasture might not have adequate quality to meet nutritional requirements. Providing a high quality forage and grain as supplemental feeds may be necessary.
For more information on feeding programs for cows, contact Barry at 403-741-6032.
Here are the articles that are referenced:
Hubbert, W. T., O. H. V. Stalheim, and G. D. Booth. 1972. Changes in Organ Weights and Fluid Volumes during Growth of the Bovine Fetus. Growth 36:217-233.