Journal Club: Association between change in body weight during early lactation and milk production in automatic milking system herds with Dr. Bill Weiss and Dr. Marcia Endres

Guests:

Dr. Bill Weiss, The Ohio State University; Dr. Marcia Endres, University of Minnesota
Co-host: Dr. Peter Morrow, Balchem

Episode 97: Association between change in body weight during early lactation and milk production in automatic milking system herds

Dr. Endres begins with a description of a dataset she collected containing individual body weights from 34 robotic milking herds. Weights were collected for every cow; every time that she came into the robotic milking station. Dr. Endres’ team was interested in the relationship between the amount of body weight change in the first 21 days of lactation and subsequent production. (7:34)

The team chose to use the first 90 days of production as their production measurement to make sure they had as many cows as possible in the dataset – the longer into lactation, the more likely to lose cows due to culling. Their results showed that 90-day production was extremely highly correlated with total lactation production. Drs. Weiss and Endres discussed the implications of young cows’ requirements for growth in the first and second lactation, which were easily observed in this dataset (13:13)

Dr. Endres’ team found a quadratic relationship between body weight loss in the first 21 days and milk production in the first 90 days of lactation. This suggests that if cows don’t lose enough, they aren’t productive. Or, if cows lose too much, they aren’t productive. The optimum amount of weight loss for cows in their second or greater lactation was around 5%, while for the first lactation cows it was 7.4%. Dr. Endres hypothesizes that cows who lost more than the optimum may have been sick because they’re probably not coming to the bunk if they’re losing that much weight. And cows who gained weight might be animals who just do not have as much genetic potential to produce milk. (17:15)

Dr. Weiss and Dr. Endres emphasize that today’s dairy cows are designed to mobilize body weight early in lactation. They are not able to eat enough to compensate for the amount of milk they are producing. Intake is going up as they move through early lactation, and cows can lose some weight and not have issues. The guests discuss the importance of an aggressive fresh cow management plan and designing diets specifically for the fresh cow group. (22:09)

Dr. Endres explains at the extremes, the highest producing cows produced around 30-35 pounds more milk each day than the lowest producing cows. But even halfway in between, it was 10-15 pounds of milk per day and those are not small numbers! Monitoring and managing body weight change has tremendous management potential, particularly with the increasing technology available to dairy herds. Identification of poor performing cows could happen sooner, and appropriate interventions could be identified earlier. (26:37)

Is there any reason this can’t be extrapolated to conventional farms that are not using robots? Dr. Endres thinks it would carry over, even though the conventional farms are feeding differently and can’t supplement individually like the robot systems. These results point to feeding fresh cows in their own group while paying close attention to access to feed and limit overcrowding. If Dr. Endres could do the study over, she would like to have reproduction and health records to compare with the milk production and weight loss data. (28:22)

Each panelist summarizes their takeaways from this research. Dr. Morrow suggests that the industry is probably not managing fresh cows nearly as intensely as they should. Their needs for calories as well as amino acids in early lactation are probably greater than we know, and we must do a better job supplying those nutrients and allowing cows to be comfortable, eat, and reach their peak potential. Dr. Weiss agrees and adds that female mammals are designed to mobilize body reserves. The idea that cows should not lose condition in early location is wrong. We don’t want them to lose too much, but losing some is perfectly normal. We need to work around that balance and include it in our formulation goals. Dr. Endres emphasizes the focus on fresh cows and suggests technology is going to allow for more and better data that will help monitor fresh cows and intervene as needed. (33:38)

Dr. Endres wraps up with a brief description of the upcoming Four State Dairy Nutrition Conference in June and Balchem’s Amino Acid pre-conference symposium on the first day to open the conference. (35:40)

The paper can be found here: https://www.jdscommun.org/article/S26…

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