Distinct responses in feed sorting, chewing behavior, and ruminal acidosis risk between primiparous and multiparous Simmental cows fed diets differing in forage and starch levels

Abstract

During early lactation, both primiparous (PP) and multiparous (MP) cows are commonly fed diets rich in starch and low in forages to support their high energy requirements. Yet, the PP cows experience this dietary challenge for the first time, which might result in higher odds for them to develop rumen and systemic health disorders. The primary objective of this study was to evaluate the effect of decreasing the amount of forages in the diet on chewing and sorting behaviors and rumen and systemic health variables in PP and MP dairy cows. Twenty-four lactating Simmental cows [8 PP, average dry matter intake (DMI) of 19.1 ± 1.1 kg/d; 16 MP, average DMI of 22.5 ± 1.1 kg/d] with a body weight of 737 ± 90 kg and 50 ± 22 days in milk were used in this study. Cows were first fed a total mixed ration with 60% forage and 40% concentrate [on a dry matter (DM) basis] considered marginal in forages for 2 wk. Then, cows were switched to a diet low in forages with 40% forage and 60% concentrate (on a DM basis) for 4 wk. Reticular pH was measured continuously with wireless pH-sensors inserted into the reticulum to calculate the subacute ruminal acidosis (SARA) index. Chewing activity was measured with noseband-sensor halters, and feed sorting was measured weekly. Blood samples were collected weekly and analyzed for metabolic and inflammation markers. Switching PP and MP cows from a marginal to low-forage diet decreased the time spent eating and ruminating per kilogram of DM. Primiparous cows chewed longer per kilogram of DMI than MP cows. Also, the PP cows sorted more pronounced for longer particles and against fine particles than MP cows did. Despite higher rumination activity per kilogram of DMI and the adaptive sorting behavior, the PP cows spent on average 4.6 h/d longer below a pH of 5.8 and had a higher SARA index (i.e., area pH <5.8/DMI) than MP cows, especially during the first week of the low-forage diet (9.5 vs. 4.8). The concentration of liver enzymes increased with the lowforage diet, which was especially pronounced in the PP cows. In conclusion, this study demonstrated greater susceptibility of PP cows to SARA and liver damage than MP cows fed the same diets. Although PP cows demonstrated greater chewing and ruminating activity per kilogram of DMI, as well as adapted sorting behavior in favor of large particles during the low-forage high-starch feeding, they developed more severe signs of SARA. This suggests higher forage fiber requirements for PP cows and the need for improved feeding strategies to mitigate rumen fermentation disorders during early lactation in these cows.

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

“…Research in recent years has indicated different susceptibilities to SARA among cows in different lactations [ 10 , 11 ]. One contributing factor to lesser susceptibility is an increase of the rumen-mucosa thickness, and thereby absorptive capacity, with the duration of concentrate feeding and with increased lactation numbers [ 12 , 13 ].…”

Distinct serum metabolomic signatures of multiparous and primiparous dairy cows switched from a moderate to high-grain diet during early lactation

“…For this, this study surveyed 393 serum metabolites of primiparous and multiparous dairy cows during medium- (M diet) and high-grain (H diet) feeding. This metabolome analysis was part of a broader study (Stauder et al 2020 ), in which cows fed H diets showed an impaired rumination activity and increased risk of rumen acidosis, especially during the first week (H-wk1). This impaired metabolic status was accompanied by milk fat depression and increased concentration of liver enzymes in the serum (Stauder et al 2020 ).…”

“…This experiment was part of a larger study and detailed information about cows, feeding, and experimental design, ethical committee protocols as well as results with respect to feed intake, sorting, chewing activity, milk components, and rumen acidosis index have been reported in our companion paper (Stauder et al 2020 ). Briefly, twenty-four early-lactating Simmental cows were used.…”

“…A summary of dry matter intake, milk yield, and the rumen acidosis index of the PP and MP cows is given in Table S1. Details regarding recording of dry matter intake, milk yield and the analyses of milk composition as well as these results are reported in Stauder et al ( 2020 ). The feeding model of this study, aiming to induce a rumen acidotic challenge by increasing the grain level in the diet, is similar to a previous model established by our team (Kröger et al 2019 ).…”

“…Daily diet was fed as a total mixed ration and consisted of high quality forages such as grass silage, corn silage, and a concentrate mixture. Diet ingredients and chemical composition are given in Table S2, whereas details of feed sampling and analyses are given in Stauder et al ( 2020 ).…”