To understand the epidemiology of colostrum production, we collected records of colostrum yield and an indicator of colostrum quality, Brix percentage, from 5,790 primiparous and 12,553 multiparous cows on 19 mid- to large size (620 to 4,600 cows) New York Holstein dairy farms.
Colostrum records showed yield was greatest in May from primiparous cows and in June from multiparous cows (see figure). Interestingly, primiparous cows produced the lowest yield of colostrum in October, whereas colostrum yield from multiparous cows was lowest in February.
The seasonality shown in colostrum yield supports previous research findings and observations from dairy producers. However, we lack knowledge on the mechanisms regulating colostrum synthesis and the factors that could be contributing to this phenomenon.
This led us to the question: Which cow characteristics and dry cow strategies are associated with colostrum yield and Brix percentage? The goal of the study was to identify cow characteristics and environmental factors as well as dry cow feeding and management practices associated with colostrum production.
Differences between cows
Individual cow characteristics, such as parity, breed, and length of pregnancy, are known to influence colostrum quality, yet relatively little information is available to understand if these variables influence colostrum yield. Using the above-mentioned colostrum records, we identified several characteristics related to colostrum production.
Regardless of parity, we noted colostrum yield and Brix percentage varied widely between cows. The greatest colostrum yield was found in cows entering parity 2; colostrum yield was lowest in cows entering parity 1, 4, or 5 or greater. In addition, colostrum Brix percent rose with parity, although the proportion of cows with high-quality (greater than or equal to 22% Brix) colostrum was not different between primiparous and multiparous cows.
Interestingly, we found that the length of pregnancy and the calf’s sex both influenced colostrum production. Multiparous cows with a longer gestation length (283 to 293 days) were shown to have nearly a 1.5 pounds greater colostrum yield compared to cows with a shorter gestation length (263 to 273 days). These results might suggest colostrum yield is influenced by calf birth weight, although we were not able to explore this in our study.
Cows giving birth to a heifer calf had lower colostrum yield compared with those cows giving birth to a bull or twin calves. In addition, both colostrum yield and Brix percent were lower with a stillborn calf compared to a live calf. While the exact mechanisms are unknown, these relationships suggest the calf influences colostrum production. In addition, a farm’s colostrum supply could be influenced by the proportion of heifers calving and a herd’s stillbirth rate.
The seasonal decline in colostrum yield follows a similar trend as the temperature-humidity index and photoperiod over a years’ time. However, to date, no research has investigated relationships between the housing environment and colostrum production.
Using in-barn environmental sensors, we collected temperature-humidity index as an indicator of heat stress, as well as light intensity in the close-up dry cow pen at each participating farm. Using this information, we found that multiparous cows exposed to a higher temperature-humidity index and light intensity in the immediate prepartum period had greater colostrum yield, but colostrum Brix percent was lower when exposed to a higher temperature-humidity index during the seven days before calving. However, colostrum yield from primiparous animals was not influenced by environmental conditions. These results emphasize the need for more work to determine if altering the in-barn environment could be a strategy to affect colostrum production.
Ways to counter low supply
Producers have great interest in tweaking management strategies that could improve colostrum production. We were interested in investigating the dry period length and close-up dry cow feeding program as possible opportunities for optimizing the colostrum supply.
The length of the dry period has previously been found to alter colostrum production. We also found this relationship with colostrum yield, as cows with a longer dry period had greater colostrum yields. For comparison, cows with a dry period shorter than 47 days had 2 pounds less colostrum than cows with a 47 to 67-day dry period and 5 pounds lower yield than cows with a dry period of longer than 67 days. In addition, colostrum from cows with longer than a 67-day dry period had a greater Brix percent than colostrum from cows with a dry period of 67 days or less.
We also considered components of the close-up diet. Feeding moderate starch (18.6% to 22.5% of dry matter [DM]) and moderate crude protein (13.6% to 15.5% of DM) were associated with a higher colostrum yield. In addition, a less severely negative dietary-cation-anion-difference (DCAD) (> -8.0 mEq/100 g) was associated with the greatest colostrum yield. A higher colostrum Brix percent was associated with a close-up diet with low starch (≤ 18.5% of DM) and a moderate DCAD level (-15.9 to -8.0 mEq/100 g).
In recognition of the seasonal decline in colostrum yield, dairy producers have an opportunity to alter colostrum management programs. One such practice would be storing excess colostrum. In fact, 18 producers (94.7%) in our study reported storing colostrum in the refrigerator or freezer.
Like milk, rapid bacterial growth can occur in colostrum when it is not promptly cooled and stored in a proper manner. To mitigate this risk, colostrum should be cooled immediately after collection.
For short term storage, colostrum can be refrigerated for a maximum of two days. With the addition of an FDA-approved preservative, it can remain in the refrigerator for four to five days. Although bacterial growth is reduced at lower temperatures, extended storage in the refrigerator will elevate the risk of a high bacterial load being delivered to the calf. For long-term storage, it is recommended to freeze colostrum for up to six months, avoiding self-defrosting freezers that could potentially damage frozen colostrum.
The results from this study show colostrum production follows a seasonal pattern and identified cow characteristics, environmental variables, and management strategies associated with colostrum production. However, future studies are needed to determine the cause and effect relationship of these complex interactions.
If dairy producers are struggling with periods of low colostrum supply, there are opportunities for improvement. Work with an informed adviser to record colostrum production and track farm-specific changes over time, review colostrum management programs, and consider the feasibility of altering dry period management to optimize colostrum supply.