The author is president of the William H. Miner Agricultural Research Institute, Chazy, N.Y.Nutritionists rightly focus on ration formulation, but the best ones understand that management expertise and cow comfort can make or break a ration. In order for a cow to respond optimally to the ration placed in front of it, the cow requires a physical and social environment that allows the proper balance between eating at the feedbunk and resting and ruminating in a comfortable stall or other resting area.
Over the years, several highly useful cow comfort indices have been developed and used on-farm to aid in assessing how well the facilities and the diet meet the cow’s needs. These measures can be made routinely on farm, both by the farmer and their nutritionist, to assess lying, standing, ruminating, and eating times.
If one of these comfort indices is found to be out of sync, then it is a safe bet that the cows in that herd or pen are not responding as well as they could to the ration given them. For the commonly used cow comfort indices, lying time is the most important measure.
Four indices of cow comfort are typically used, and each has strengths and weaknesses. The following is a brief description of each index, how to measure it, and when to use it. These indices of cow comfort should be measured when cows are motivated to lie down. This allows the best measure of how well the environment accommodates natural resting activity. Ordinarily, you should observe the cows about two hours before or about one hour after milking.
Cow comfort and resting
The cow comfort index dates to the 1990s and is commonly used as a general indicator of cow comfort within a pen. This index is simply defined as the proportion of cows in a stall or touching a stall (as in perching) that are actually lying down.
The cow comfort index assesses a cow’s motivation to enter a freestall and lie down. So, it can reflect overall comfort of the stall or resting area. Are the stalls well bedded and groomed? Are the dimensions correct? A lower cow comfort index has been associated with increased lameness, which is another important reason to monitor it.
The cow comfort index is useful for both freestall and tie stall barns. However, there are two major limitations to using this index. First, this index overestimates cow comfort in overcrowded pens because overcrowding tends to elevate competition for stalls and overall stall occupancy.
Second, the cow comfort index is not associated with mean or average daily lying time. A common misconception is that a higher cow comfort index means more hours per day of lying time. A well-managed herd should have a cow comfort index greater than or equal to 0.85. In other words, 85% of cows touching the stalls should be lying down.
Stall standing index
About a decade after the cow comfort index was developed, researchers at the University of Wisconsin School of Veterinary Medicine proposed the stall standing index as a way to predict lameness potential. It’s another useful tool to assess the quality of the cow’s environment. The stall standing index is defined as the proportion of cows in contact with stalls that are standing. In other words, it is the inverse of the cow comfort index.
A higher stall standing index is associated with longer daily standing times. In fact, a stall standing index greater than 0.20 translates to stall standing times of over two hours per day and elevated risk of lameness.
So, if you observe a pen where more than 20% of the cows are standing in the stall, you should be on the lookout for lame cows. Lame cows will have less mobility, reduced dry matter intake, and lower milk yield than predicted by the ration formulation software.
Similar to the cow comfort index, the stall standing index may overestimate cow comfort in overcrowded pens as cows often lie down more quickly in overcrowded situations where competition for stalls is keen.
A well-managed herd or pen of cows should attain a stall standing index of less than or equal to 0.15. Or, no more than 15% of cows in contact with the stalls should be standing.
Using the stall use index
The stall use index for overcrowded pens is a bit more complicated to calculate than either the cow comfort index or the stall standing index. However, it provides tremendous insight into the well-being of cows within a pen.
This index is defined as the proportion of cows not actively feeding within a pen that are lying down. So, the numerator is total cows lying in a stall and the denominator is total cows in the pen minus cows that are actively feeding. Well-managed herds should have a stall use index of 0.75 or more.
The main advantage of the stall use index is that it accurately reflects cow comfort within an overcrowded pen, especially when stocking density approaches 130% of stalls or more. With the prevalence of overcrowding on dairy farms, measuring the stall use index becomes critical to understanding whether cows have adequate access to stalls and feed.
The stall use index takes into account those cows that are essentially “wasting time” idling in alleys. Cows waiting in alleys for a stall to open up are a hallmark of overcrowded pens, and these cows are truly wasting their time because they are neither eating nor resting.
Like the cow comfort index, one limitation of the stall use index is that it is not associated with daily lying times. But its major strength is that it does account for cows that are lying down and eating — both very productive uses of the cow’s time.
Monitor rumination activity
I would guess that every nutritionist and farmer subconsciously monitors rumination index when they walk through a pen of cows. Essentially, the rumination index is the proportion of cows ruminating that are lying down.
The rumination index has been validated against daily rumination time. On average throughout the day, you should expect to see 50% to 60% of cows ruminating when lying in the stall. There are times throughout the day when this percentage will be higher or lower.
Research at Miner Institute observed a positive correlation between rumination index and rumination time in minutes per day in lactating Holstein cows. This is important because it gives us confidence that, when we see 50% or so of cows ruminating, it translates to about 500 to 520 minutes per day of ruminating time, which is what the lactating dairy cow requires for healthy rumen function. In contrast, if you only observe about 40% or less of the cows ruminating, that relates to approximately 450 minutes or less per day of rumination. This is too low for optimal rumen function in most cases.
Better response to rations
The bottom line is that routinely monitoring these indices of cow comfort pays dividends as we try to optimize the cow’s environment. That’s because comfortable cows respond better to rations. The indices should be an indispensable tool in every farmer’s and every nutritionist’s toolbox. An environment that fosters natural resting and ruminating activity as judged by these indices will allow the cow to respond most favorably to the formulated ration.