Seasonal decline in colostrum yield

Providing adequate amounts of quality colostrum to dairy calves within the first hours after birth improves calf health, growth and lifetime performance. In the fall, many herds are challenged with low colostrum production from fresh cows. This issue appears to be herd-dependent and cow-dependent and is likely affected by several factors.

Environmental factors

Seasonality plays a role in low or insufficient colostrum production. Cows calving in the fall are exposed to long-day photoperiods during later gestation. Ideally, a dry cow would experience eight hours of daylight and 16 hours of darkness. In addition, these same cows are often exposed to heat stress during their dry period. Changes in hormonal pathways associated with colostrum synthesis occur as early as 40-50 days pre-calving.

Ambient temperatures are also cooler in the fall. Just as heat stress can be detrimental in the summer months, cold stress can present challenges to dry cows. Cold stress can reduce dry matter intake, reduce mammary blood flow and impair immune reactivity. Water intake can also be a greater challenge in cold weather. Lack of water availability (quality or quantity) will also contribute to lower DMI.

Management factors

Cow comfort plays a significant role in adequate colostrum production and overall success of the transition period. Stalls need to be adequately sized with a comfortable lying surface. Group housing needs to be clean and dry with adequate square footage per cow. Always offer plenty of bunk space and provide heat abatement in the summer months.

The length of the dry period affects colostrum quantity. A dry period that is less than 30 days significantly reduces colostrum yield. This appears to be a bigger concern with animals coming into their first or second lactations. A recent Cornell University study concluded that cows with a dry period shorter than 47 days had 2 pounds less colostrum than cows with a 47- to 67-day dry period.

The timing of colostrum harvest will impact the quality and quantity of colostrum. Make sure staff know the importance of timely colostrum harvest and sufficient milk-out.  Excessive udder edema or the presence of mastitis can further complicate the success of the first milk-out. Although not always practical, some farms have found success harvesting second-milking colostrum from cows with initial low yields while maintaining colostrum quality.

Nutritional factors

Sometimes cows calving in the fall are fed corn silage that was fermented for a year and then are switched to silage that has been fermented for less time. This impacts rumen microbial protein yield and rumen microbial turnover, which can interrupt DMI.

Dry cow feeds are often lower in energy, but this should not mean lower quality.  Remove any feeds from the dry cow ration that have a hint of mold. Certain mycotoxins may interfere with hormonal control of lactogenesis, and negatively impact DMI and immune status.

Nutritional strategies to improve DMI could have a positive impact on colostrum yields. This may require a slight increase in energy in colder weather conditions depending on housing and cow comfort. However, increasing energy appears to have little to do with colostrum yield if nutrient requirements are already met.

Ensure that dry cow rations have adequate concentrations of nutrients that impact immune function, such as selenium, vitamins A, D, and E, manganese, and magnesium.  In some cases, colostrum quantity has improved with the addition of a bypass protein source to increase rumen undegradable protein and improve microbial protein production.

While low colostrum yields are more prevalent in the fall, you may be able to minimize this challenge by focusing on the environmental, management and nutritional factors at play. Looking forward, consider how you might be able to accumulate surplus colostrum in the high-production months to ensure a reserve supply of high-quality colostrum when you need it.

Barry Visser is a nutritionist for Vita Plus.