Feeding Diets Moderate in Physically Effective Fibre Alters Eating and Feed Sorting Patterns without Improving Ruminal pH, but Impaired Liver Health in Dairy Cows

Abstract

The main challenge in dairy cattle feeding is to find a balance between the energy and physically effective fibre (peNDF), required to maintain rumen health. In an attempt to regulate the balance between energy intake and rumen buffering, we hypothesized that the content of peNDF in the diet modifies eating and feed sorting patterns of the cows. Sixteen lactating Simmental cows were switched from a diet high in peNDF, with which they were fed for one week, to a diet moderate in peNDF for four weeks. Data showed that during the moderate peNDF feeding the cows increased sorting for medium-sized particles and avoided both long and very fine particles. In addition, cows decreased their eating time per meal, but increased the number of meals per day, obviously attempting to decrease the amount of fermentable substrate per time unit while maintaining high levels of nutrient/energy intake. Although these changes during the moderate peNDF feeding went along with a lower diurnal variation of ruminal pH, feeding of the latter diet did not prevent ruminal pH drop and increased the level of all liver enzymes, indicating liver tissue damage. In conclusion, the altered eating, chewing, and sorting behaviour of the cows during the moderate peNDF feeding could not alleviate the deficiency in peNDF, which resulted in ruminal pH depression and impairment of liver health variables.

Starch-Rich Diet Induced Rumen Acidosis and Hindgut Dysbiosis in Dairy Cows of Different Lactations

“…The change from a moderate concentrate (40% DM) diet to a high-concentrate (60%, DM) diet caused on average a decrease in reticular pH below the threshold of 6.0 as an indicator for SARA, as published in our accompanying paper [ 17 ]. The prolonged feeding of HC probably caused an increased flow of carbohydrates to the hindgut and resulted in the fecal pH decrease by 0.4 down to 7.4 in HCwk4.…”

“…However, the relevant correlation of approximately 0.5 between ruminal-pH values and fecal-pH values defines dependency. Continuous measurements of ruminal pH and rumination activity clearly show that these parameters are subjected to diurnal variations, depending on feeding time points [ 17 ]. Only a few studies investigated diurnal changes in fecal pH.…”

“…The concentrate was based on barley (63%), soybean meal (15%), corn (9%), solvent-extracted canola-meal (8%), and mineral-vitamin supplements. Exact feed composition and chemical analysis of the diets is published in [ 17 ]. The diet was offered twice daily (07:30, 17:30) as a total mixed ration for ad libitum intake in automated feeding troughs (Insentec B.V., Marknesse, the Netherlands), that continuously measured feed intake.…”

“…The data was processed using RumiWatch Manager 2 (V2.1.0.0. ; RumiWatch System, ITIN+Hoch GmbH, Liestal, Switzerland) as described by [ 17 ]. A clinical examination of all cows was carried out at the beginning of the experiment by the performing veterinarians.…”

“…This study is part of a larger research project. Therefore, results of performance, milk constituents, ruminal pH, dry matter intake (DMI), chewing activity, and sorting along the feeding model are described in [ 17 ].…”