Improving the dry matter intake as crucial aspect in alleviating the impact of heat stress

Published on 4-04-2023 - By Kemin

Supplement with Choline and balancing dietary cation-anion to improve dry matter intake

Stress can be regarded as something that is applied by an external source to an animal that has an effect on the normal physiological behavior of that animal. The intake of dry matter is decreased during stress, which has a direct effect on the output of dairy animals. Heat stress and the stress during transition phase cause more losses to dairy animals among multiple stressors.

Cows under heat stress will reduce dry matter intake (DMI) by 20 – 25%, which accounts for ~40 – 50% of the associated milk yield decline. As a result of the decreased DMI, cows under heat stress enter negative energy balance (NEBAL) regardless of their stage of lactation, which can lead to losses in body weight (BW) and body condition score (BCS). Therefore, it can be an important factor to consider nutrition strategies that lower the NEBAL associated with heat stress and allow cows to sustain milk production.

Supplementing choline and balancing dietary cation anion (DCAB) has potential to improve dry matter intake and thus sustaining/improving productivity during the condition of heat stress.

Our Sr. Product Manager, Deepak Dubey, gives you more insight in his presentation on managing dry matter intake during heat stress and transition stress.

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Dairy Cow from Dr. Baumgard

Effect of Heat Stress on Feed Intake, Digestion and its Utilization

Reduced feed intake is caused by rising environmental temperatures. High environmental temperatures may have an effect on the rumen microorganisms that synthesize various nutrients, essential for ruminant nutrition. Furthermore, during dehydration and heat stress, there is a decrease in blood flow to the rumen epithelium (Hales et al., 1984) and a decrease in rumination (Aganga et al., 1990). Heat stressed animals have a slower fractional rate of digesta passage in the GI Tract than animals in the thermo neutral zone.

Correlation of dry matter intake with incidences of metabolic disorders

Reductions in dry matter intake and energy balance are associated with metritis, mastitis and ketosis. In recent research (Baez et. al., 2019), a retrospective longitudinal study was performed using the data from 476 cows (139 primigravid and 337 multigravid) from 9 experiments conducted from the year 2007 to 2015 at the University of Florida research dairy unit, located in the city of Hague, Florida. It was concluded that each 0.1-percentage point decreases in the average dry matter intake as a percentage of body weight (DMI%BW) increased the odds of metritis by 8%, odds of clinical mastitis by 10 % and odds of ketosis by 8%.

Table: Effect of dry matter intake on metritis, clinical mastitis and ketosis



Odds ratio

95% Confidence Interval

P- value





Clinical mastitis









Dry matter intake and hypocalcemia are also correlated. Rumination involves a complex series of muscle contractions that bring a bolus of ingesta to the mouth for further mastication before it is swallowed again. Healthy cows ruminate 8 to 9 h/d. Hypocalcemia is known to disrupt nerve and muscle function. Goff et. al., (2020) studied the correlation between plasma calcium (Ca) levels and rumination activity. Plasma Ca concentration during the middle of the first day of lactation (0.5 d) was highly correlated with rumination rate on the first day of lactation, when many cows were hypocalcemic. Plasma Ca concentration at time 0.5 d was also correlated with rumination rate on the second day after calving, even though blood Ca concentrations had increased in most cows by day 2.

Choline improves dry matter intake

In terms of health solutions, Choline nutrition has received the highest focus due to its role in better liver functioning. Apart from higher production levels, Choline’s role in improving dry matter intake, immunity and health creates a strong argument for increased provision of bioavailable Choline. Supplementing choline alters the plasma NEFA concentration. This increases the export of hepatic fat and results in less hepatic fat concentration and thus better liver functioning, which ultimately leads to optimal dry matter intake.

Supplementation of rumen-protected choline (RPC) has attracted major research efforts during the last decade, assuming that choline improves liver function by increasing very low-density lipoprotein exportation from the liver, thereby improving metabolic profiles, milk production, and reproduction. To understand better the importance of RPC, a meta-analysis was conducted (Elke et. al., 2019) to evaluate the effects of RPC supplementation on feed intake, milk production performance and metabolic profiles of dairy cows early postpartum.  

Arshad, (2020) conducted another meta-analysis of supplementing rumen protected choline during the transition period on performance and health of parous dairy cows. Mixed model meta-analysis was conducted including the random effect of experiment and weighting by the inverse of the standard error of the means squared. Twenty-one experiments with up to 66 treatment means and 1313 prepartum parous cows were included in this meta-analysis. Prepartum averaged RPC feeding was for 22±6.0 day and post-partum averaged RPC feeding was for 57.5±42.2 day. Research data from year 1984 to 2018 was included in this up to date meta-analysis.

Table : Effect of choline supplementation on dry matter intake, body weight gain and Body condition score (BCS) in dairy cows


Choline ion, g/d






DMI, kg/d





BW, kg/d





BCS, 1 to 5






DMI, kg/d





BW, kg/d





BCS, 1 to 5





Improvement of 200 g dry matter intake prepartum and 500 g postpartum with improved body weight and body condition score can be easily correlated with optimal metabolic health and performance from dairy cows.

Dietary cation anion balancing (DCAB) improves dry matter intake

Cows going through transition phase during heat stress can even have more negative consequences. For example, Cows fed with cationic diets (diets having a positive charge due to higher concentration of sodium, potassium, calcium and magnesium) during pre-partum phase are more likely to suffer decreased dry matter intake, increased incidences of milk fever or hypocalcemia post calving. Anionic/acidogenic diets (diets having a negative charge due to higher concentration of chloride, sulfur and phosphorus) promote a more acidic metabolic state (lower blood pH)) that is associated with increased dry matter intake and a reduced incidence of hypocalcemia post calving.

It is likely that most diets are cationic in nature, based on the dietary ingredients used in the diet of close-up cows. One of the main reasons for this is that these ingredients are fundamentally cationic.

Santosh et al. (2019) recently published a meta-analysis on 42 experiments, including 134 treatments with 1803 cows. The resulting equations from the statistical models predicted that reducing the Dietary Cation-Anion Difference (DCAD) from +200 to −100 mEq/kg would increase blood total calcium on the day of calving from 1.86 to 2.04 ± 0.05 mM, DMI postpartum 1.0 kg/d, and milk yield 1.7 kg/d in parous cows.

Table: Effect of DCAB on dry matter intake and animal performance


DCAB, mEq/kg diet




DMI, kg/d




Milk, kg/d




FCM, kg/d




Milk fat, kg/d




Milk proetin, kg/d




Body weight, kg





Overall, focusing on improving the intake of dry matter during the heat stress in dairy cows is important.

Based on two recently published meta-analysis on supplementation of rumen protected choline and one meta-analysis on DCAB, it can be concluded that Choline and DCAB significantly improve dry matter intake which is critical and important in optimizing farm profitability.

Interested to see the results on how Choline improves dry matter intake during the transition and early lactating phase? Download our meta-analysis to get the numbers.