To evaluate the effects of calcium propionate (CaP) supplementation on feed intake, milk yield and milk composition, energy balance, blood metabolites and urine ketones in early lactation Holstein dairy cows from 1 to 63 days in milk (DIM), 32 multiparous Holstein dairy cows, blocked by lactation number, previous 305-day milk production, and expected calving date, were arranged into four groups in a randomized block design. Treatments were control, LCaP, MCaP and HCaP with 0, 100, 200 and 300 g calcium propionate per cow per day respectively. The supplement of food grade CaP (99.8% of CaP) was hand-mixed into the top one-third of the daily ration. Cows were fed ad libitum a total mixed ration consisting of equal proportion of forage and concentrate. Feed intake, milk yield and components were not affected by CaP supplementation. The energy balance, expressed as the difference between energy input and output, tended to be higher (p = 0.08) for CaP-supplemented cows during the 63-DIM period, especially during the first 21-DIM lactation. Calcium propionate-supplemented cows showed a trend (p = 0.09) towards less loss of body weight (BW) during the 63-DIM period. Concentrations of glucose in plasma and insulin in serum were higher for cows fed CaP relative to control and linearly (p < 0.01) increased with increasing CaP supplementation. Concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA) and urine ketones were lower for CaP-supplemented cows at 7, 14 and 21 DIM of lactation and linearly (p < 0.01) decreased with increasing CaP supplementation. These results indicated that nutrient digestibilities and energy status may have been improved.

The objective was to evaluate the effects of selenium-yeast (SY) supplementation on rumen fermentation, lactation performance and feed digestibilities in dairy cows. Twenty-eight multiparous (2.5±0.3 parity) Holstein dairy cows, averaging 625±18.2kg of BW, 63±3.0days in milk and average daily milk production of 26.2±0.5kg/cow were used in a replicated 4×4 Latin square experiment. Treatments were: control, LSY, MSY and HSY with 0, 150, 300 and 450mg selenium yeast (Sel-Plex®, 1g/kg selenium, produced from Saccharomyces cerevisiae CNCM I-3060) per kg of diet dry matter (DM), respectively. Experimental periods were 45days with 30days of adaptation and 15days of sampling. Ruminal pH was lower for MSY than for control and was linearly (P=0.03) decreased, whereas total VFA concentration was linearly and quadratically (P≤0.01) increased with increasing SY supplementation, with the least for control, followed by LSY and HSY, and the highest for MSY. Ratio of acetate to propionate was lower for LSY, MSY and HSY than for control, and was linearly and quadratically (P≤0.01) decreased as SY supplementation increased due to an increase in molar proportion of propionate. Ruminal ammonia N content was lower (P≤0.01) for MSY and HSY than for control and was linearly decreased (P≤0.01) with increasing SY supplementation. Dry matter intake, proportions and yields of milk fat, protein and lactose were not affected (P>0.05). Milk yields and 4% FCM were higher (P≤0.05) for LSY and MSY than for HSY and control. Milk selenium content was linearly and quadratically (P≤0.01) increased as increasing SY supplementation, with the least for control, followed by LSY and MSY, and the highest for HSY. Digestibilities of DM, organic matter (OM), crude protein (CP), ether extract (EE), aNDF and ADF in the total tract were higher (P<0.01) for LSY and MSY than for control and HSY. The results indicate that supplementation of diet with SY improved rumen fermentation, milk yields, milk selenium, and feed digestion. It was suggested that the SY stimulated the digestive microorganisms or enzymes in a dose-dependent manner. In the experimental conditions of this trial, the optimum selenium-yeast dose was about 300mg per kg diet DM.

SUMMARYThe objective of the present study was to evaluate the effects of betaine supplementation on rumen fermentation, lactation performance and plasma characteristics in dairy cows. Twenty multiparous Holstein dairy cows (597±11·8 kg body weight (BW), 88±4·5 days in milk (DIM) and average daily milk production of 26·3±0·5 kg/cow) were used in a replicated 4×4 Latin square experiment. The treatments were: control (without betaine), low-betaine (LB), medium-betaine (MB) and high-betaine (HB) with 0, 50, 100 and 150 g supplemental anhydrous betaine/cow/day, respectively. Betaine was hand-mixed into the top one-third of the daily ration at feeding. Experimental periods were 30 days with 15 days of adaptation and 15 days of sampling. Dry matter (DM) intake was not affected with increasing the betaine supplementation. There were linear increases in milk yield and fat-corrected milk yield (corrected to 40 g fat/kg) and a linear and quadratic increase in milk fat concentration with increasing the betaine supplementation, whereas the proportion and yield of milk protein and lactose, and feed efficiency, were not affected. Ruminal pH and ammonia N linearly decreased, whereas total volatile fatty acid (VFA) concentration linearly and quadratically increased with increasing the betaine supplementation. The ratio of acetate to propionate (A:P) linearly increased from 3·06 to 3·53 as betaine supplementation increased. Digestibility of DM linearly increased, whereas digestibilities of organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and acid detergent fibre (ADF) in the total tract were quadratically increased with increasing the betaine supplementation. Plasma concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) were lower for betaine supplementation than for control, and were linearly decreased by betaine supplementation. The results indicate that supplementation of mid-lactation dairy cow diets with betaine increased milk yield through increased feed digestion. Betaine supplementation may benefit lactation performance when methionine supply is limiting.

The objective of this study was to evaluate the effects of malic acid (MA) on feed intake, milk yield and composition, blood metabolites and energy balance in early lactation Holstein dairy cows from 1 to 63 day in milk (DIM). Twenty-eight multiparous Holstein dairy cows, blocked by lactation number, previous 305-d mature equivalent milk production, and expected calving date, were arranged into four groups in a randomized block design. Treatments were: control (without MA), LMA, MMA and HMA with 70,140 and 210 g malic acid per cow per day, respectively. The supplement of food grade MA (99.8% of MA) was hand-mixed into the top one-third of the daily ration. Cows were fed ad libitum a total mixed ration consisting of equal proportion of forage and concentrate. Milk yield increased (P=0.04), but feed intake and milk components were not affected (P>0.05) by MA supplementation. The energy balance, expressed as the difference between energy input and output, tended to be higher (P=0.08) for MA supplemented cows during the 63-DIM period MA and supplemented cows showed a trend (P=0.07) toward less loss of BW during the 63-day period, especially during the first 21-day of lactation. Concentrations of plasma glucose and serum insulin were higher for cows fed LMA, MMA, and HMA relative to control and linearly (P<0.01) increased with increasing MA supplementation. Concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA) and urine ketones were lower for MA-supplemented cows at 7,14 and 21 DIM of lactation and linearly (P<0.01) decreased with increasing MA supplementation. Although feed intake was not affected, milk yield increased, MA-supplemented cows experienced higher concentrations of plasma glucose and serum insulin, lower concentrations of plasma BHBA and NEFA, and lower concentrations of urine ketones, suggesting that nutrient digestibilities and energy availability may have been improved. (C) 2009 Elsevier B.V. All rights reserved.

The objectives of this study were to evaluate effects of feeding propylene glycol (PG) on feed intake, milk yield and milk composition, blood metabolites and energy balance in Holstein dairy cows from 1 to 63 days in milk. Thirty-two multiparous cows, blocked by lactation number, previous 305-day milk production and expected calving date, were arranged into four groups in a randomized block design. Treatments were: control, low PG, medium PG and high PG with 0, 150, 300 and 450 ml PG per cow per day, respectively. The supplement of food grade PG (0.998 g/g PG) was hand-mixed into the top one-third of the daily ration. Cows were fed ad libitum a total mixed ration consisting of forage and concentrate (50 : 50, dry matter basis). Feed intake, milk yield and milk components were not affected (P > 0.05) by PG supplementation. Overall, body weight (BW) loss tended (P < 0.08) to be linearly reduced, and energy status was linearly improved with increasing PG supplementation. Concentrations of glucose in plasma were higher for cows fed PG relative to control (55.6 v. 58.9 mg/dl) and linearly increased (P < 0.01) with increasing PG supplementation. Plasma concentrations of non-esterified fatty acids and beta-hydroxybutyrate were linearly increased, but urine acetoacetate concentration was quadratically changed with the highest for control diet and the lowest for 450 ml/day of PG. These results indicated that supplementation of PG in the early lactating cow diets had minimal effects on feed intake and milk production, but may potentially reduce contents of milk fat and milk protein. Supplementation of early lactating dairy cow diets with PG is beneficial in terms of improving energy status and reducing BW loss.

The objective was to evaluate effects of glycerol supplementation on feed intake, milk yield and milk composition, blood metabolites and energy balance in Holstein dairy cows from 4 to 63 days in milk (DIM). Thirty-six multiparous cows, blocked by lactation number, previous 305 day mature equivalent milk production and expected calving date, were arranged into four groups in a randomized block design. Treatments were: control (without glycerol), glycerol-low (LG), glycerol-medium (MG) and glycerol-high (HG) with 100, 200 and 300g glycerol per cow per day, respectively. The supplement of food grade glycerol (0.998g/g glycerol) was hand-mixed into the top one-third of the daily ratio. Cows were fed ad libitum a total mixed ratio consisting of equal proportions of forage and concentrate. Feed intake, milk yield and its components were not affected by glycerol supplementation. The energy balance, expressed as differences between energy input NEI and output (NEM+NEL) in MJ per cow per day, was higher (P<0.04) as glycerol supplementation level increased, especially during the first 17 and last 20 days of the 63 day period. Glycerol-supplemented cows tended (P<0.06) toward less loss of BW, especially first 17 and last 20 days of the 63 day period. Concentrations of glucose in plasma were higher for cows fed glycerol relative to control (54.1mg/dL versus 58.1mg/dL, respectively) and linearly increased (P<0.01) with increasing glycerol supplementation level. Concentrations of non-esterified fatty acids, beta-hydroxybutyrate and urine ketones were lower for glycerol-supplemented cows at 7, 14 and 21 days of lactation and linearly (P<0.01) decreased with increasing glycerol supplementation. Although milk yield and feed intake were not affected, glycerol-supplemented cows has a more positive energy status (higher concentrations of plasma glucose, lower concentrations of plasma beta-hydroxybutyrate, lower concentrations of urine ketones), suggesting that net energy availability may have been increased.