While many people set New Year's resolutions regarding diet, weight and body condition, many dairies could benefit from implementing similar resolutions for their dry cows. There is no “one size fits all” approach to dry cow nutrition and management that consistently results in minimal health problems, high milk production and efficient reproductive performance in the subsequent lactation. However, there are some common themes to keep in mind while feeding dry cows:
1. Maintain dry matter intake through calving.
2. Optimize nutrient intake and supply (e.g. energy, metabolizable protein, minerals, and vitamins).
3. Maintain body condition score (BCS) while minimizing variation among cows.
4. Minimize environmental and social stressors.
Dry matter intake can be maintained, while energy intake is controlled by formulating diets appropriately for fiber and energy density. For example, cows will easily consume >150% of their energy requirement on corn silage-based diets. Typically this is too much energy. Controlled-energy diets typically incorporate low-energy feedstuffs (e.g. straw, grass hay or haycrop silage). Inclusion of these feedstuffs allow cows to consume feed ad libitum without over-consuming energy. Basically, the cows eat to rumen fill.
Once dry matter intake is set, the diet can be formulated with protein feedstuffs to supply at least 1100 g/day of metabolizable protein. Some farms are having excellent transition results with feeding additional metabolizable protein (up to ~1300 g/day) or using rumen-protected amino acids to meet the requirements for immune function, mammary development and protein reserves. Protein reserves are used for metabolic functions in the first few weeks of lactation when the cows experience negative protein balance along with negative energy balance.
Over-conditioned cows (BCS ≥3.5 on a 1 to 5 scale where 5 is fat) before calving typically have more metabolic disorders and mobilize more body fat after calving than do thinner cows. Attention to diet formulations in late lactation can help achieve the appropriate BCS (~3.25) at dry off. Recent work from Germany showed overconditioned, nonpregnant, nonlactating cows had changes in key regulator proteins of adipose tissue metabolism which was accompanied by impaired insulin sensitivity. These are physiological changes that need to be prevented in dry cows.
In addition, work from Illinois showed excessive accumulation of visceral (internal) fat due to overfeeding energy for an 8-week period may be detrimental to cows, especially during the transition period because of inflammation and impaired liver function. Unfortunately, BCS is not a very good indicator of internal fat. Thin cows will respond metabolically as if they were fat when they are overfed.
Common observations with overfeeding or excessive insulin resistance are:
1) Large decreases in intake as cows approach calving.
2) Low intake or sluggish increases in intake in fresh cows.
3) Excessive body weight or BCS gain during the dry period.
4) Excessive body weight or BCS loss during early lactation.
5) Higher incidence of subclinical and clinical ketosis and displaced abomasum.
Find the Miner Institute January Farm Report online here: http://whminer.org/farmreport.html