Effect of phytogenic feed additive, yeast and organic minerals on dairy cows subjected to ruminal acidosis

Abstract

A phytogenic feed additive (PHY), non-viable yeast and organic minerals can reduce ruminal acidosis in dairy cows subjected to slug-feeding. Fifteen Holstein cows (40.0 ± 6.9 kg/d, 103 ± 54 days in milk, 607 ± 81 kg) were fed a sequence of treatments, control (CTL), PHY [0.01 % of dry matter (DM) of Digestarom], and YOM (PHY + 0.075 % of DM of non-viable yeast + 0.15 % of DM of organic sources of S, Cu, Mn, Zn, Se) in 3 × 3 Latin squares with 35-d periods (22-d adaptations). Cows were milked 3 ×/d and individually fed on a corn silage based total mixed ration with 31.2 % starch in DM. During days 29 and 32 of each period, feed was removed from each cow at 1900 h and cows were fed ad libitum at 0700 h of days 30 and 33 to induce slug-feeding. Data obtained over time during days 23 to 35 were analyzed as repeated measures with the MIXED procedure of SAS. The model had the effects of square, cow (square), period, treatment, day, and the interaction between treatment and day. Two contrasts were evaluated: 1) Phytogenic feed additive: CTL vs PHY+YOM and 2) Yeast + organic minerals: PHY vs YOM. Statistical significance was declared at P ≤ 0.05 and tendency at P ≤ 0.10. The ruminal acidosis induction protocol induced daily variation in most variables and there were very few treatment × day interactions. Feed restriction on days 29 and 32 induced spikes in dry matter intake (DMI) and in the duration of the first daily meal and reductions in milk yield, body weight, and ruminal pH on days 30 and 33. Cows fed PHY+YOM had higher DMI than cows fed CTL (23.7 vs 23.0 kg/d) and there was a tendency for YOM to increase DMI relative to PHY (23.9 vs 23.5 kg/d). Milk yield did not differ (33.0 kg/d), but energy-corrected milk (ECM) was higher on PHY+YOM than CTL (31.9 vs 31.0 kg/d). The concentrations in milk of fat, preformed, mixed and de novo fatty acids were all increased by PHY+YOM relative to CTL. Cows fed PHY+YOM had higher daily rumination time than CTL. Milk composition of cows fed YOM did not differ from PHY. Ruminal pH measured at 30-min intervals, fermentation profile, microbial yield and fecal pH did not differ. The intake of digestible organic matter (DOMI) was increased on PHY+YOM relative to CTL and tended to be increased on YOM relative to PHY. The total-tract digestibility of DM and OM tended to be higher and jugular blood pH was lower on YOM than PHY. Cows fed PHY+YOM had higher partial pressure of CO2 in venous blood than CTL. The second induction of slug-feeding (d 33) induced higher jugular blood pH and base excess than the first induction (d 30). Gut permeability evaluated by the plasma Cr concentration after pulse dosing Cr-EDTA into the rumen and blood serum lipopolysaccharide binding protein concentration did not differ. Cows fed the phytogenic feed additive (PHY+YOM) had greater DMI, DOMI, ECM, fat yield and rumination time than cows fed CTL without change in ruminal fermentation and gut permeability, and the supplementation of yeast + organic minerals (YOM) tended to increase DMI and diet digestibility relative to PHY.