Long Hay Feeding and Abnormal Calf Oral Behavior

Nutritional or physiological issues can and do impact intake and behavior. Dr. Al Kertz of Andhil LLC joins us to talk about calf feeding behavior on a texturized starter and hay.

September 21, 2023

7 Min Read

By Al Kertz, PhD, PAS, DIPL ACAN
St. Louis, MO 63122[email protected]

In the late 1990s, research on animal behavior and welfare was instituted especially by a group at the UBC (University of British Columbia) (Kertz et al., 2017).  This included considerable studies related to dairy calves.  Graduate students from this program have since located and developed similar programs at other universities.  While I have found many of these studies with considerable merit and value, at times they are confounded because the authors did not consider the impact of the physical form of the starter on behavior.  This could then predetermine what the study results would be.

The fundamental issue is that if preweaned calves, or even weaned  calves, have marginal rumen acidosis, that affects intake, rumination, digestibility, and daily gain.  All of this is seen in the following then in vogue early weaning program study (Porter et a;. 2007; Kertz 2019) done in the early 1970s at Cornell University while I was a graduate student there.




Daily gain, 0-8 weeks, lb,



Starter intake, 0-8 weeks, lb.



First week ruminating



% of time ruminating



Rumen pH



DM digestibility, %



ADF digestibility, %



NDF digestibility, %



It was in the 1980s when a major feed manufacturer produced and marketed an all-pelleted starter for feeding calves without forage.  That led to an outbreak of these calves chewing up wood within reach!  I have seen that more recently in this photo of calves 2 months old having been weaned with free choice pelleted starter available in a wooden manger.  I could hear them chewing the wood before I got close for this picture below.  The calves are simply trying to reduce their rumen acidity by chewing which produces saliva which when swallowed buffers their rumen pH from being so acidic.

Another confounding factor when feeding hay in calf behavioral calf studies (and in other calf studies too) is gut fill.  Unfortunately, there is no simple way to measure gut fill.  It is rarely done because it involves sacrificing calves.  But one of the few studies in which this was done was by the UBC group (Khan et al., 2011). While the starter was described as “texturized”, it only contained “14% flatted barley, 13% flatted oats, and 10% steamed corn” for a total of 37% processed grains.  Obviously, that was inadequate as the rumen pH was 5.06 when no hay was available .  But one treatment had hay available free choice.  That allowed calves to buffer their acidic rumen by eating some hay.   However, that resulted in 11 lb less weight gain when adjusted for the 10.4 lb more gut fill.  Without these gut fill measurements, it would appear that hay was beneficial as the authors and title indicated whereas it really reduced true weight gain by 11 lb.


BW with rumen ingesta, lb



BW without rumen ingesta, lb



Rumen/reticulum with digesta, lb



Rumen pH



This is some background related to this study (Downey et al., 2023) of calf behavior when providing hay either in a bucket or a novel pipe feeder. The starter was partly or poorly texturized based on a photo kindly provided by Dr. Cassandra Tucker.  Twenty-seven female Holstein calves born from June through September 2019 were assigned to one of 3 treatments: Control, with long hay in a bucket, or with long hay through 2-inch large holes in a 4-inch diameter PVC pipe.  After administrating 18 liters of colostrum over the first 5 days, a 26% protein/16% fat milk replacer mixed at 14% solids was bottle fed twice daily at 1.9 liters per feeding from 5 to 9 days, 2.4 liters from 10 to 23 days, 2.8 liters from 24 to 49 days. Weaning began at 50 days of age by removing the morning feeding until full weaning at 60 days of age.  Water and the starter were fed ad libitum along with a 7.5-inch chopped orchard grass/fescue hay for the non-control treatments. All calves had 3 buckets for water, starter, and hay but with no hay in control and pipe treatment buckets.  Calves were individual housed in sand bedded hutches.  Adjustments were made to randomized allocation by balancing for birth weight across treatments. 

 Calves fed hay consumed more starter and water (usually at 4:1 water to dry matter intake) than control calves fed only the starter without hay, there was a significant week x treatment interaction, and calves fed hay by bucket consumed more hay than calves fed hay via the pipe with holes (data in graphs in the paper).  There was considerable variability noted especially in water intake.  That is why more than 9 calves per treatment should have been uses (15 to 20) as noted previously (Kertz and Chester-Jones 2004).

Daily gains (Table 1) followed the intake pattern described.  The pattern is not surprising since I would have expected calves fed the poorly texturized starter alone would have had marginal rumen acidosis.  Similarly, and consistent with marginal rumen acidosis, calves fed hay ate more starter than control calves.

Table 1. Calf body weights and daily gains by treatment.


Birth weight, lb




Preweaned daily gain, lb




All 60 days daily gain, lb




Final body weight, lb




Hay  intake daily, lb




Starter intake daily, lb




References cited of other calf studies in which hay had some beneficial effects appeared to have used pelleted starters as far as I can tell.  My plea for more complete data and descriptions on calf studies still needs some improvement (Kertz 2017).  Another UBC study (Welk et al, 2022) used a “texturized starter” consisting of (on as-is basis) 31.2% flaked barley and 15.0% flaked corn.  That totals to 46% which meets the ~45% minimum I recommend for texture (Ghaffari and Kertz 2021); but barley starch is highly fermentable so I recommend only cracking or rolling barley and not using more than about 20%..

 Other study observations were:

  • Calves bucket and pipe fed hay ruminated in an equal percentage of observations.

  • Bucket and pipe fed hay calves spent more observations eating overall than control calves.

  • Bucket calves fed hay spent more observations drinking water than control or pipe fed hay calves.

  • All calves spent similar observation time sucking on the milk replacer bottle teat.

  • Control calves spent more observational time manipulating the empty pipe feeder than pipe fed hay calves and bucket fed hay calves.

The Bottom Line

 Nutritional or physiological issues can and do impact intake and behavior.   In this case, calves did not do well on a poorly texturized starter and ate hay available to “titrate” their ruminal marginal acidosis.   Their feeding behavior reflected this situation.   Feed a well-texturized starter to avoid this issue.


Downey, B. C. and C. Tucker. 2023.  Providing long hay in a novel pipe feeder or a bucket reduces abnormal oral behaviors in milk-fed dairy calves.  J. Dairy Sci. 106:2022-2241.

            Kertz, A. F. and H. Chester-Jones.  2004.  Guidelines for measuring and reporting calf and heifer experimental data.  J. Dairy Sci. 87:3577-3580.

            Kertz, A. F.  2017.  Letter to the Editor:  A call for more complete reporting and evaluation of experimental methods, physical form of starters, and results in calf research.  J. Dairy Sci. 100:851-852.

Kertz, Alois F., Dairy Calf and Heifer Feeding and Management—Some Key Concepts

and Practices.  Outskirts Press, July 31, 2019, 166 pages.  See pages 61-65.


            Ghaffari, M, and A, F, Kertz. 2021. Review:  Effects of different forms of calf starters on feed intake and growth rate:  A systematic review and Bayesian meta-analysis of studies from 1938 to 2021.  Appl. Anim. Sci. 37:273–293.

Khan, M. A., D. M. Weary, and M. A. G. von Keyserlingk.  2011.  Hay intake improves performance and rumen development of calves fed higher quantities of milk.   J. Dairy Sci. 94:3547-3553.   

            Porter, J. C., R. G. Warner, and A. F. Kertz.  2007.  Effect of fiber level and physical form of starter on growth and development of dairy calves fed no forage.  The Prof. Anim. Scientist 23:395-400.

Welk, A., H. W. Neave, H. B. Spitzer, M. A. G. von Keyserlingk, and D. M. Weary. 2023.  Effects of intake-based weaning and forage type on feeding behavior and growth of dairy calves fed by automated feeders.  J. Dairy Sci. 105:9119–9136.

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