WHAT’S HAPPENING ON THE FARM
Spring is typically our slow calving season and this year is no different. We struggle to get cows pregnant in the heat of the summer (usually July and August) even though our barn is designed to help minimize heat stress — fans and sprinklers in the barn and milking parlor, high sidewalls, and cows that aren’t grouped above 123% stocking density. But still our pregnancy rate suffers in the summer. It’s kind of frustrating in view of the efforts we’ve made to cool the cows. In the summer we have bred cows once a day, in the morning before the heat of the day, but perhaps we should not even try to breed our cows in the few really hot weeks we have each summer. Just some of our thoughts as we gear up for cropping and warmer weather!
In our dry cow barn, built in 2008, we have an animal handling area with a holding area, chute and scale setup and a couple of lanes for separating out groups of cows. In most cow trials conducted at Miner Institute the cows are weighed every week, but we also use the chute and scale in our normal dairy management. All cows are weighed at dry off (vaccinated too while they’re restrained) and then weighed again when they move to close-up (18-24 days before their due date). After freshening, each cow is weighed again and then moved to the milking barn. With this information we can monitor weight gain/loss during the dry period.
Recently we weighed a group of early lactation cows (2nd lactation and greater at 30-70 DIM). The group of cows was fairly small — 17 animals — but we learned some interesting things about our herd. The cows with a smooth transition into lactation lost on average 250 lbs from freshening to 30-70 DIM. The couple of cows with health problems – DA, lameness, mastitis, lost 100-175 lbs more than their healthy counterparts.
Weight loss in early lactation isn’t the whole picture, though. What is the body condition of these cows? We know we don’t want “fat” dry cows, but while trying to avoid the issues associated with over-conditioned dry cows, have we gone too far in the opposite direction, drying cows off on the thin side – say a BCS of 3.0. We think a 250 lb. weight loss in early lactation is OK if the animal started out with sufficient body condition (around a 3.5 BCS). Some of our cows are making 140-150 lbs of milk per day in early lactation. Are they entering that period of negative energy balance in early lactation with sufficient body reserves? If a high group looks thin – a lot of cows with a BCS of 2.25-2.5, is it because of excessive weight loss after freshening or did they start off their lactation with insufficient body condition? Of course, the dry cow, fresh, and high group rations play a key role in starting the cow off to a successful lactation and minimizing the length of time a cow is in a negative energy balance.
In several weeks we will reweigh this group of 17 cows at 80-120 DIM. Perhaps weighing cows in early lactation should be incorporated into our normal management but also along with body condition scoring at the same time we weigh the animals!
Please note that this is a “What’s Happening on the Farm” article and isn’t intended to be a recommendation for the appropriate/normal weight loss in early lactation …these are just some things we’ve been discussing this past month. Right, wrong, or crazy, at least we are still asking questions!
— Anna Pape
A little thin for a dry cow?
Adequate but not excessive body condition for transitioning into lactation.
Dry cows and heifers in the animal handling area.