Quantifying the impact of frequent diseases and syndromes on calf health using the opinions of producers and veterinarians: Toward calf disability weights
Journal of Dairy Science, Vol. 108, No. 3, 2025
This article, from researchers from the University of Montreal and Lactanet, aimed at quantifying the impact and disability weight of frequent diseases or syndromes of preweaning dairy calves using the perceptions of producers and veterinarians. The second objective was to compare the opinions of producers and veterinarians about these issues. For this, they conducted a survey to obtain demographic information and opinions of 39 dairy producers and 52 veterinarians. The majority of the producers surveyed were from Quebec.
The researchers provide some background information explaining that population perception is used to have a broad understanding of the impact of a disease on individual health. This approach is used to determine what is called the disability weight (DW) for various diseases. This measure, which is related to the severity of a particular health state, was initially employed in the Global Burden of Diseases, Injuries, and Risk Factors project for humans. The global aim of this project was to develop a recognized health measure, disability-adjusted life years (DALY), which allows for the aggregation of various diseases within a population into a single comparable health metric. One DALY represents the loss of one year of “full health.” To calculate this metric, the DW for different diseases in a particular population is combined with the respective number of disease cases and assessed over a period to determine the time lived with a disability. The number of years lost due to premature death is then added to this measure, deriving the final value of DALY.
In dairy science, this same concept (DW) was investigated by U.S. researchers for 12 common diseases in cows. The lowest DW was observed for retained placenta and diarrhea, whereas the highest was observed for right displaced abomasum. The DW specific for a disease was combined with the number of incident cases and the disease average duration to obtain the number of days of life lost due to illness. This measure was then combined with the losses related to early culls or deaths to derive the final metric called disease-adjusted lactation days of life lost (DALact). This system was used to quantify the number of days of life loss for a cow during a lactation. The DALact is a measure that can be used to identify the most important health-related limiting factors at the farm level.
The authors justify the current study to help establish DW and health metrics focusing on calves. They identify two reasons why this is important: one is the fact that diseases and health events during the preweaning period have various short- and long-term impacts. The second is due to the economics of raising calves. The average rearing cost per heifer from birth to first calving is high ($4,859), with the preweaning period being the costliest, as shown recently in Quebec. The main objective of this study was therefore to quantify the impact of frequent dairy calf diseases and syndromes, as well as to determine their DW, using the opinions of dairy producers and veterinarians. A secondary objective was to compare the opinions of producers and veterinarians regarding the impact of frequent dairy calf diseases and syndromes.
The study identified the highest average impacts for the presence of a fracture (6.49/10), arthritis (6.22/10) and congenital defects (6.03/10), whereas the lowest impact was observed for the presence of a wound or abscess (3.42/10). The opinions of producers and veterinarians were similar for most of the selected diseases and syndromes; however, statistical differences were observed for arthritis (producers = 5.13 versus veterinarians = 6.88), umbilical infection (producers = 3.65 versus veterinarians = 4.74) and dystocia (producers = 3.87 versus veterinarians = 4.58).
The authors conclude that producers and veterinarians mostly agreed on the impact of different diseases and syndromes. Further, they say, estimating DW is a crucial first step in creating a health measure for dairy calves. Similar to humans, this metric will be important for health comparative analysis for producers, veterinarians and industry workers.
Associations of body condition score, body condition score change and hyperketonemia with mastitis, reproduction and milk production
Journal of Dairy Science, Vol. 108, No. 3, 2025
This study, from researchers from the universities of Ohio and Michigan, aimed at investigating the association between body condition score (BCS), BCS change, blood beta-hydroxybutyrate (BHB – a marker of fat mobilization) and hyperketonemia (HYK) with mastitis, pregnancy per artificial insemination, pregnancy loss, milk yield and risk of leaving the herd on a Michigan dairy farm that uses an automated milking system. They say that BCS and hyperketonemia have been associated with diseases, fertility and culling, but data are contradictory about their association with pregnancy loss. For the study, they recorded BCS for cows prepartum (14 days before calving) and postpartum (14-21 days after calving), and multiparous cows were evaluated for hyperketonemia between three and seven days in milk.
The authors provide some background information indicating that a long-held principle in dairy cattle husbandry is that managing BCS and minimizing hyperketonemia optimizes health and performance of dairy cattle. Loss of BCS in the periparturient period is associated with hyperketonemia because lipolysis of triglycerides releases free fatty acids into circulation, a portion of which are partially catabolized to BHB in the liver. Both BCS and hyperketonemia have been associated with health and fertility outcomes in dairy cattle. Increased BHB concentration in blood is associated with increased risk of displaced abomasum, metritis, infertility and culling. Furthermore, although a degree of increased blood BHB is a necessary adaptation to lactation, it has been negatively associated with milk yield throughout lactation. The relationship of BCS, BCS change and hyperketonemia with mastitis has also been investigated. Data indicate that cows that lose body condition tend to experience greater mastitis risk than cows that gain body condition after calving.
According to the authors, an understudied question is whether BCS or hyperketonemia are associated with pregnancy loss after first service. Approximately 10% of pregnancies are lost between 30 and 60 days postbreeding. Reducing pregnancy loss may reduce culling because reproduction is a primary reason cows exit the herd. Longer lactations that accompany poor fertility also increase BCS of dairy cows and may reduce health and fertility in subsequent lactations. Still, evidence for whether BCS or changes in BCS during the transition period are associated with pregnancy loss is inconsistent. They say that determining whether BCS, change in BCS or hyperketonemia is associated with pregnancy loss will determine whether managing BCS, its change and hyperketonemia may minimize occurrence of pregnancy loss and improve dairy cow fertility and longevity as a result.
In this study, greater body condition loss and hyperketonemia were associated with pregnancy loss. The authors say that one limitation of the experiment is that these data are from one farm with low pregnancy loss incidence and that a multifarm study investigating risk factors for pregnancy loss is necessary to verify these findings. The loss of BCS and increased BHB were associated with increased culling. Although associative, the data suggest that managing body condition and hyperketonemia may reduce pregnancy loss, reduce mastitis incidence and reduce the risk of leaving the herd.
The authors observed that prepartum BCS, change in BCS and BHB were, or tended to be, associated with pregnancy loss. Their data, although from a small dataset, suggest that thinner cows in the prepartum period have reduced risk of pregnancy loss and cows with greater BCS loss after calving, as well as cows with increased blood BHB in the first week of lactation, had greater odds of pregnancy loss. These data align with the biology because metabolites associated with excess lipolysis influence oocyte development, often reducing viability and quality. Additionally, cows with low BCS after calving, presumably cows who lost BCS after calving, and cows with hyperketonemia have had greater concentrations of inflammatory biomarkers that would impede fertility. Prepartum BCS and postpartum BCS were associated with milk yield and suggest that intermediate BCS optimizes milk yield. Also, hyperketonemia in third-or-higher-parity cows was associated with less milk yield. Managing body condition and hyperketonemia incidence continues to be important for animal welfare and dairy production.
This column brings you information regarding some of the research being done around the world and published in the Journal of Dairy Science . The objective is to bring to light areas of research that may have an immediate practical application on a dairy farm, as well as research that, even though it may not have a practical impact now, could be interesting for its future potential application. The idea is to give a brief overview of select research studies but not go into detail on each topic. Those interested in further in-depth reading can use the citations to find each study.
