28 January 2014

9 minute read

In a case study publication of the World Food and Agriculture Organisation, the pair reveal emphasise that metritis will result in reduced milk yield and ramp up the risk of culling.

Juliana Huzzey and Marina Von Keyerslingk of the University of British Columbia state that feeding behaviour, dry matter intake and social behaviour can be used for the early identification of cows at risk for metritis. 

Introduction

Maintaining healthy animals is a key component of animal welfare. An effective dairy cattle herd health programme is also critical for maintaining herd profitability. Illness can compromise production efficiency by reducing milk production and reproductive performance, and shortening the life expectancy of a dairy cow through increased rates of involuntary culling.

Traditionally, research addressing the health concerns of dairy cattle has focused primarily on aspects of nutrition, physiology and metabolism. Despite these efforts, disease incidence, particularly around the calving period, continues to be high (Table 1). Improved methods for detecting cattle that are at increased risk of becoming sick during this critical period could aid in early treatment and prevent the illness from progressing to its clinical and consequently most costly stage.

When animals are sick they commonly display a variety of symptoms, including changes in body temperature, lethargy and decreased appetite. Early research in our group (Urton et al., 2005), as well as work conducted with fattening beef steers, has shown that changes in feeding behaviour can be used to identify sick animals and even to predict morbidity. These studies, however, did not explore the relationships between intake, behaviour and health during the period around calving in the lactating dairy cow.

According to the Food and Agriculture Organization (FAO), this case study focuses on metritis (uterine infection), a common and costly disease affecting dairy cattle during the weeks following calving. Through a series of research studies conducted by our group, we have established a number of lines of evidence indicating that feeding behaviour, including DMI, and social behaviour can be used to identify cows at risk of metritis in the days before calving. More recently, our group investigated the long-term impact of metritis on milk production and culling risk, providing further evidence that metritis is a costly disorder and that overall farm profitability is likely to improve with improvements in early disease detection.

Feeding Behaviour and DMI Predict Metritis

On the average dairy farm, metritis detection occurs only during routine herd health checks by the veterinarian or trained farm staff, which take place every two to three weeks. The weekly or biweekly gaps between health checks results in many early warning signs of metritis going unnoticed until such time as the disease is in its clinical stages. A practical method for continuously monitoring the health status of dairy cows would be extremely useful for producers.

Photo 1: The electronic feed monitoring system (INSENTEC) at the University of British Columbia

At the University of British Columbia’s Dairy Education and Research Center (Agassiz, BC) an automated feeding system (INSENTEC, Marknesse, Holland; Photo 1) was used to continuously record feeding behaviour and intake of 101 Holstein dairy cows from two weeks before until three weeks after calving.

Metritis severity was diagnosed on the basis of daily rectal body temperature (BT) as well as condition of vaginal discharge that was assessed every three days after calving until 21 days in milk (DIM). Any cows diagnosed with health disorders other than metritis within 21 DIM were excluded from the study. A total of 62 cows were included in the data analysis: 12 severely metritic cows [five primiparous (PP), seven multiparous (MP)]; 27 mildly metritic cows (12 PP, 15 MP); and 23 healthy cows (five PP, 18 MP). Cows with mild metritis (purulent vaginal discharge with a foul odour and with our without a fever: temperature ≥ 39.5 °C) were clinically diagnosed on average nine days after calving, while those with severe metritis (putrid, watery, red/brown discharge with foul odour and a fever) were clinically diagnosed on average five days after calving.

Cows with severe metritis had lower DMI and spent less time at the feed bunk during the two-week period prior to calving and for nearly three weeks before the observation of clinical signs of infection (Figure 1). Cows with mild metritis also consumed less and tended to spend less time at the feed bunk during the week before calving. During the week before calving, cows were 1.72 times more likely to be diagnosed with severe metritis for every 10 minute decrease in feeding time, and for every 1 kg decrease in DMI during this period, cows were nearly three times more likely to be diagnosed with severe metritis.

Feeding time for all groups of cows was positively correlated with DMI, meaning that cows with longer feeding times also had greater DMI. However, this relationship was strongest in the severely metritic cows. These results provide evidence that sick cows (or cows that will become sick) utilize the time spent at the bunk more efficiently (i.e. when they are at the bunk they spend that time eating).

During the week before calving, cows that were later diagnosed with severe metritis also had altered social behaviour as they engaged in fewer aggressive interactions at the feed bunk (i.e. displaced others from the feed bunk less often) and consumed less dry matter compared with cows that stayed healthy during the periods following fresh feed delivery, a time when cows are highly motivated to eat. Cows with severe metritis after calving appeared to be less motivated to compete for access to feed before calving. These results may suggest that these cows are socially subordinate and unwilling to engage in interactions with more dominant individuals.

This research provides evidence that feeding behaviour, DMI and social behaviour before calving can identify cows at risk of developing metritis after calving. Whether a reduction in intake and feeding time before calving is a cause of postpartum infectious disease or is an effect of a pre-existing condition is still to be determined.

Figure 1. Average daily DMI (kg/day; A) and feeding time (min/day; B) of healthy (n = 23), mildly metritic (n = 27) and severely metritic (n = 12) Holstein dairy cows from 13 days before until 21 days after calving

Effects of Metritis on Milk Yield, Culling Risk and Reproductive Performance

To explore the long-term consequence of metritis, data from two of our previous transition cow studies were combined (Huzzey et al., 2007 and Proudfoot et al., 2009). Using only data from multiparous cows, a population of 43 healthy animals (no fever or other clinical signs of disease by 21 days postpartum) and 16 severely metritic animals (see definition above) were identified. Individual DMI was monitored for 21 days after calving for all experimental animals using the INSENTEC electronic feeding system. During this time, cows had ad libitum access to both feed and water.

Metritis during early lactation had an overall negative impact on the milk production of multiparous cows. These animals produced less milk than those that remained healthy. This reduction in milk yield was experienced not only during the metritis infection but also throughout the first 20 weeks of lactation, even though all sick cows received veterinary care (Figure 2). Cows with metritis and lower milk yield consumed approximately 3.5 kg/day less DMI during the first 21 days after calving. The reduction in feed intake observed over the first 21 days in lactation for cows with metritis may help to explain the lower daily milk yield observed in these animals over the first 20 weeks of lactation; it remains unknown whether these cows had lower feed intake beyond three weeks after calving.

Figure 2. Multiparous cows with metritis have lower average daily milk yields throughout the first 20 weeks of lactation compared with healthy multiparous cows

Multiparous cows with metritis were more likely to be culled than those that remained healthy. In total, eight of the original 16 cows with metritis were culled (50 per cent) while only nine of the original 43 healthy cows were culled (20 per cent). The odds of being culled were 3.8 times greater for cows with metritis than for healthy cows. Cows that were culled produced less milk than those that were not culled during the first 12 weeks of lactation. Culling decisions were made before any indications of reproductive problems (indeed, most of the culled cows were never bred). The decision to cull was likely driven by a combination of ill health and low production in the first weeks of lactation.

Other researchers have shown metritis to be associated with compromised reproductive performance, as pregnancy rates are 4.5 per cent lower for cows with metritis than for cows without metritis (Figure 3; Overton and Fetrow, 2008).

Figure 3. Median days open (DOPN) and pregnancy rate (PR) for cows with metritis (grey line) and normal cow (black line)

The Economic Burden of Uterine Disease

The financial burden associated with metritis comes from both direct and indirect costs. In a study aimed at describing the economic impact of metritis, Overton and Fetrow (2008) identified four key areas where costs are incurred: 1) reduced milk production; 2) increased culling risk; 3) decreased reproductive performance; and 4) additional treatment costs.

Using data collected from 500 cattle diagnosed with metritis (comparable to the severe metritis category in our studies described above) and a series of assumptions (e.g. milk price, salvage value for culled cows, treatment type, etc.; see paper for details), these researchers estimated the following costs as a consequence of metritis:

1. Reduced milk production: US$83/case
2. Increased culling rate: US$85/case
3. Reproductive complications: US$109/case
4. Treatment: US$53–109/case

Using this information, these researchers estimated that costs due to metritis could reach US$330 to US$386 per diagnosed case. To place that cost in the context of the entire dairy operation, if a 1 500-cow dairy herd had a 30 per cent metritis incidence rate, the costs associated with metritis could range from US$148 000 to US$174 000 annually.

References

Huzzey, J.M., Veira, D.M., Weary, D.M. & von Keyserlingk, M.A.G. 2007. Prepartum behavior and dry matter intake identify dairy cows at risk for metritis. J. Dairy Sci. 90: 3220–3233.

Ingvartsen, K.L., Dewhurst, R.J. & Friggens, N.C. 2003. On the relationship between lactational performance and health; is it yield or metabolic imbalance that causes production diseases in dairy cattle? A position paper. Livest. Prod. Sci. 73: 277–308.

Overton, M. & Fetrow, J. 2008. Economics of Postpartum Uterine Health. In Proceedings, 3rd Annual Dairy Cattle Reproduction Conference, pp. 39–43.

Proudfoot, K.L., Veira, D.M., Weary, D.M. & von Keyserlingk, M.A.G. 2009. Competition at the feed bunk changes the feeding, standing, and social behavior of transition dairy cows. J. Dairy Sci. 92: 3116–3123

Urton, G., von Keyserlingk, M.A.G. & Weary, D.M. 2005. Feeding behaviour identifies dairy cows at risk for metritis. J. Dairy Sci. 88: 2843–2849.

Wittrock, J.M., Proudfoot, K.L., Weary, D.M. & von Keyserlingk, M.A.G. 2011. Short Communication: Metritis affects milk production and cull rate of Holstein multiparous and primiparous dairy cows differently. J. Dairy Sci. 94: 2408–2412.

January 2014