Many dairy owners and/or managers consider fresh heifers as an excellent way to improve milk quality because they have never been exposed to daily milking situations and potential pathogens.
Fresh heifer somatic cell count (SCC) issues are often hidden and difficult to detect. Unfortunately, in most cases, fresh heifers actually contribute to a higher herd SCC rather than dilute the existing SCC. The goal for any dairy operation is to have less than 10% of the heifers calve with an SCC over 200,000 or a linear score of 4.0. I have studied records from thousands of dairies, and it is typical to find 25% to 35% of the heifers over this threshold level on their first test.
People might say that fresh heifer SCC usually goes down the following test. Over the past 20 years, I have seen dairies drop the number of high-SCC heifers to under 10% with the right changes in management practices, resulting in overall positive changes to the operation.
High SCC in fresh heifers impacts your milk check
Two studies looking at more than 150,000 animals analyzed the impact of fresh heifers having an SCC over 200,000 at their first test over the entire lactation. In 1990, Dr. Steve Stewart showed on over 200,000 heifers’ full lactations that those with a first test SCC over 200,000 – regardless of where the SCC dropped after that – had over 1,400 pounds (636 kilograms) less milk in that lactation. Dr. Mark Kirkpatrick did a similar study in 2015 on 164,000 heifers and found these animals produced 1,583 pounds (720 kilograms) less milk in that lactation.
His study also looked at other factors and found that animals with SCC over 200,000 on first test left the herd three times sooner and had clinical cases of mastitis 57 days sooner than those who tested with a lower SCC. Animals with a high SCC or an early-lactation case of clinical mastitis were also declared open for 17 more days than herdmates. Interestingly, this study showed the negative impact of a high SCC on the first test (1,583 pounds) was more costly than a case of clinical mastitis (1,007 pounds).
Based on these two studies, fresh heifer SCC cannot be ignored based on economics alone.
A program to catch high-SCC heifers early
I developed an easy program to monitor fresh heifers to determine whether there is a problem at calving time that can provide results much earlier than waiting for the first test day. This procedure is being done on herds milking 100 cows as well as those milking 7,000 cows or larger.
Heifers that calve on Sunday, Monday or Tuesday get purple duct tape around both rear legs. Heifers that calve Wednesday, Thursday, Friday or Saturday get yellow duct tape around both rear legs. On Friday, the herd manager or similar person attends the milking of the fresh animals and finds all the heifers with purple duct tape and performs a California Mastitis Test (CMT) on those animals. Any animal with a positive CMT reaction is cultured and treated according to herd protocol for the bacteria isolated. On Wednesday, the herd manager attends to milking of the fresh animals and finds all heifers with yellow duct tape, does a CMT on those animals and follows the same protocol. This only requires extra effort at the dairy two milkings a week, but the results can be very positive.
The best thing about the fresh heifer CMT protocol is knowing how to manage your milk quality issues better. Knowing whether animals are actually freshening with high SCC or getting infected in the first two weeks after calving can help you determine how to manage each case effectively.
I think it is a great idea to culture all fresh animals (heifers and cows) because so many issues come from these animals. Finding mycoplasma, prototheca and common contagious bacteria, especially Staph aureus, can be managed early before these organisms can be transmitted to other animals in the herd.
The more information the dairy has, the better the farm can be managed and can prevent huge issues from occurring.
Preventing infections
If animals are calving with an infection, evaluating the pre-fresh and heifer facilities is critical. Dirty heifers will generally cause more SCC issues at freshening. If CMTs are negative at calving but SCC is high on first test, then one should concentrate on the facilities post-calving, the milking routine for fresh animals and the milking equipment being used to milk the fresh animals.
Occasionally, the fresh milking parlor has older equipment and can be poorly maintained. Many fresh animals are milked with a floor bucket so colostrum can be harvested, and floor buckets have serious restrictions in milk flow, such as less than 5/8-inch internal diameter nipples, which can pose a problem. I've seen dairies upgrade their bucket lids to 3/4-inch internal diameter and they have had fewer issues.
Keeping heifers in a clean, dry and comfortable environment for three to four months pre- and post-calving is critical to preventing new infections. A common mistake many dairies make is putting heifers on a bedded pack before calving, where serious bacterial udder contamination can occur, increasing the risk of new infections. Overcrowded bedded packs can pose a larger risk. Fewer and fewer dairies use bedded packs aside from the calving process and have reduced labor needs and costs by using well-designed freestalls instead. In most cases, you can put more animals in the same size of barn with freestalls than in a barn with a bedded pack.
I've observed over the past 15 years that many dairies that have issues with too many high-SCC animals have worked with their herd veterinarian and developed effective prevention protocols. I encourage all dairies to cultivate a close working relationship with their herd veterinarian because that person knows how to assist you in developing the best protocol for your dairy.
The two most common programs dairies with excellent milk quality are using to reduce the number of infected animals are as follows. Dr. Stephen Oliver from the University of Tennessee published a study about pretreating heifers, which showed a very positive result. His research showed treating heifers 10 to 14 days before calving with an approved lactating tube lowered mastitis, SCC and increased milk production. Another popular protocol is to dry-treat heifers 30 to 45 days before calving using an approved dry cow treatment, along with either an external or internal teat sealant. Many of the dairies I work with are doing this procedure under the guidance of their herd veterinarian. I recently surveyed the herds I consult for that have bulk tank SCC under 100,000 and found that 75% were pretreating heifers by using one of the two procedures listed above.
In my 50 years of experience, managing the level of SCC and mastitis in fresh heifers is critical to achieving excellent milk quality. There are many important ways to improve milk quality on your dairy, but don’t let fresh heifers contribute to your issues. A solid, well-designed program can have a positive difference on your dairy.
