Search

The objective of this study was to evaluate the effects of 2-methylbutyrate supplementation on growth performance and rumen development in pre- and post-weaned dairy calves. Fifty-six Chinese Holstein male calves with 15 days of age and 46.5 ± 0.37 kg of body weight (BW) were randomly assigned to one of four groups. The treatments were: control, low-2-methylbutyrate (LMB), moderate-2-methylbutyrate (MMB) and high-2-methylbutyrate (HMB) with 0, 3, 6 and 9 g 2-methylbutyrate per calf per day, respectively. Supplemental 2-methylbutyrate was hand- mixed into milk in pre-weaned calves and the concentrate portion of post-weaned calves. The study lasted 75 days, including a 15-day adaptation period and followed by a 60-day sampling period. Calves were weaned at 60 days of age. Six calves were chosen from each treatment at random and slaughtered at 30 and 90 days of age. Body weight, dry matter (DM) intake and stomach weight were measured, samples of ruminal tissues and blood were determined. DM intake increased linearly (P < 0.03) for post-weaned calves and overall DM intake with increasing 2-methylbutyrate supplementation and was higher for MMB and HMB than for LMB and control (P < 0.05). Average daily gain (ADG) increased linearly (P < 0.05) for pre-weaned calves, post-weaned calves and overall ADG with increasing 2-methylbutyrate supplementation, and was higher for MMB and HMB than for LMB and control (P < 0.05). Total stomach weight for pre- and post-weaned calves increased linearly (P < 0.05) and was higher for MMB and HMB than for LMB and control (P < 0.05). The ratio of rumen weight to total stomach weight tended to increase linearly (P = 0.055) for pre-weaned calves and increased linearly (P = 0.019) for post-weaned calves, whereas the ratio of abomasum weight to total stomach weight decreased linearly (P < 0.05) for pre-weaned calves and post-weaned calves with increasing 2-methylbutyrate supplementation. The ratio of total stomach weight to body weight for pre-weaned calves and post-weaned calves increased linearly (P < 0.05) and was higher for MMB and HMB than for LMB and control (P < 0.05). Both the length and width of rumen papillae, and the relative expression of mRNA for growth hormone receptor (GHR) and 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) in rumen mucosa tended to increase linearly for pre-weaned calves, but increased linearly (P < 0.05) for post-weaned calves and was higher for MMB and HMB than for LMB and control (P < 0.05). Blood concentrations of BHBA increased linearly (P < 0.05) for post-weaned calves with increasing 2-methylbutyrate supplementation and was higher for MMB and HMB than for LMB and control (P < 0.05). Blood concentrations of GH and IGF-1 increased linearly (P < 0.05) for pre- and post-weaned calves with increasing 2-methylbutyrate supplementation and was higher for MMB and HMB than for LMB and control (P < 0.05). The present results indicated that 2-methylbutyrate accelerated growth of calves by improving rumen development and its ketogenesis. The 2-methylbutyrate stimulates the growth performance and rumen development of dairy calves in a dose-dependent manner. In the experimental conditions of this trial, the optimum 2-methylbutyrate dose was about 6.0 g 2-methylbutyrate per calf per day. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of branched-chain volatile fatty acids (BCVFA) supplementation on growth performance, ruminal fermentation, nutrient digestibility, hepatic lipid content and gene expression of dairy calves. Forty-eight Chinese Holstein male calves (10 months of age; 345 ± 6.4 kg of body weight [BW]) were assigned randomly to four treatments with 0, 60, 120 and 180 mg BCVFA per kg BW per day for each calf. Supplemental BCVFA was hand-mixed into the top third of the daily ration and fed to calves for 100 days to the experimental treatments. Supplementation of BCVFA in calves ration increased ADG and feed conversion linearly. Dry matter (DM) intake was unaffected, but digestibilitiy of DM, organic matter, crude protein, ether extract, neutral detergent fibre and acid detergent fibre increased linearly with increasing levels of BCFVA supplementation. Similarly, Supplementation of BCVFA linearly decreased ruminal pH and ammonia-N but increased total VFAs. Molar proportion of acetate linearly increased, whereas propionate linearly decreased and the ratio of acetate to propionate increased linearly with increasing BCVFA in rations. Relative mRNA expressions of peroxisome-proliferator-activated receptor α and carnitine palmitoyl transferase-1 linearly increased with BCVFA levels. The results suggested that BCVFA supplementation improved ruminal fermentation, nutrient digestibility and growth of calves with promoted hepatic lipid oxidation. Due to the unsignificant difference between 120 and 180 mg groups for all parameters, the optimum supplementary dose of BCVFA was 120 mg per kg BW per day. [ABSTRACT FROM AUTHOR]

This experiment was to evaluate the effects of rumen-protected pantothenate (RPP) on ruminal fermentation, microbial enzyme activity, bacteria population and urinary excretion of purine derivatives in growing beef steers. Eight ruminally cannulated first-generation crossbred (Blonde d′Aquitaine × Simmental) beef steers, averaging 12 months of age and 363 ± 7 kg of body weight (BW), were allocated into a replicated 4 × 4 Latin square design. Four treatments were control, low-RPP (LRPP), medium-RPP (MRPP) and high-RPP (HRPP) with 0, 0.32, 0.48 and 0.64 g RPP per kg dietary DM, respectively. Steers were fed a total mixed ration and dietary concentrate to corn silage ratio was 50:50 based on a dry matter (DM) basis. The experiment included four periods and lasted for 96 days, each period contained 14 days of adaptation and 10 days of data collection. Ruminal pH decreased linearly with increasing RPP supplementation and was lower for MRPP than for control. Ruminal total VFA concentration increased linearly with increasing RPP supplementation and was higher for MRPP than for control. The acetate to propionate ratio increased linearly due to the unchanged acetate molar proportion and the tendency towards decreased propionate proportion. Ruminal DM and neutral detergent fibre degradability of corn silage increased quadratically, whereas DM and crude protein degradability of concentrate mix increased linearly with increasing RPP supplementation. Activities of carboxymethyl-cellulase, cellobiase, xylanase and α-amylase increased linearly and was higher for MRPP than for control. Populations of R. albus, R. flavefaciens, F. succinogenes, B. fibrisolvens, P. ruminicola and R. amylophilus increased linearly and quadratically with increasing RPP supplementation. Urinary excretion of purine derivatives increased linearly with increasing RPP supplementation and was higher for HRPP and MRPP than for LRPP and control. The results indicated that dietary supplementary RPP improved ruminal fermentation, in situ ruminal degradation and urinary excretion of purine derivatives by stimulating bacteria growth and microbial enzymes secretion. It is suggested that supplementary RPP regulated bacteria growth and microbial enzymes secretion in a dose-dependent manner. Under the current experimental condition, the appropriate dose of RPP was at 0.48 g per dietary DM for growing crossbred beef steer. [ABSTRACT FROM AUTHOR]

This experiment was done to investigate the influences of supplementary rumen-protected folic acid (RPFA) on ruminal fermentation parameters, microbial enzyme activity, cellulolytic bacteria and urinary excretion of purine derivatives in growing beef steers. Eight ruminally fistulated Jinnan beef steers (398.4 ± 1.9 kg) were used in a repeated 4 × 4 Latin square experimental design. The treatments were: control (without RPFA), low RPFA (LRPFA), medium RPFA (MRPFA) and high RPFA (HRPFA) with 0, 0.6, 1.2 and 1.8 g RPFA per steer per day, respectively. The dietary corn silage to concentrate ratio was 50:50 (dry matter [DM] basis). The dry matter intake was confined to 95% of voluntary intake. Mean ruminal pH was quadratically reduced with altering RPFA supplementation, and was the lowest for MRPFA and HRPFA, highest for the control, and intermediate for the LRPFA. Ruminal total VFA concentration was quadratically increased with increasing RPFA supplementation and was higher in MRPFA than in control. The ratio of acetate to propionate was quadratically increased due to the increased acetate concentration and the unchanged propionate concentration. Ruminal degradabilities of DM and neutral detergent fibre of corn silage, and DM and crude protein of concentrate mix increased quadratically with increasing RPFA supplementation. Ruminal enzyme activity of cellobiase, xylanase, pectinase and α-amylase quadratically increased and was higher in MRPFA than in control. The populations of B. fibrisolvens , R. albus, R . flavefaciens and F. succinogenes quadratically increased with altering the supplementary PRFA. Urinary excretion of purine derivatives quadratically increased with altering RPFA supplementation and was higher in HRPFA and MRPFA than in LRPFA and control. The results indicated that dietary supplements of RPFA improved ruminal fermentation, in situ ruminal degradation and urinary excretion of purine derivatives. It was suggested that the RPFA regulated the activity of rumen microbe or enzymes in a concentration-dependent manner. Under this experimental condition, the appropriate dose of RPFA was at 1.2 g/d for steer. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of dietary supplements of rumen-protected folic acid (RPFA) on lactation performance, energy balance, reproductive performance and blood parameters of dairy cows. Ninety-six multiparous Holstein cows were assigned to four groups of 24 each according to their previous 305-days milk production. The treatments were: control, low RPFA (LRPFA), medium RPFA (MRPFA) and high RPFA (HRPFA) with 0–3 g RPFA/cow per day, respectively. Supplements of RPFA were top-dressed and manually mixed into the upper one third of the ration during the morning feeding from 3 weeks before the expected calving date to 15 weeks after parturition. Dry matter (DM) and net energy (NE) intakes, milk yield, milk protein content and production increased linearly ( P < 0.05) with increasing RPFA supplementation, whereas milk fat content and production only tended to be linearly increased. Cows supplemented with RPFA showed a similar pattern ( P < 0.05) of decreased loss of body weight (BW) and improved energy balance (expressed in MJ/cow/day) during the 105 days in milk (DIM) period. Concentrations of glucose in plasma, folate and methionine in serum increased linearly ( P < 0.05), whereas concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA) and serum homocysteine linearly ( P < 0.01) decreased. Total conception rate and the percentage of cows pregnant at 150 DIM linearly increased ( P < 0.05), DIM at first breeding and breeding per conception tended to change linearly with increasing RPFA supplementation. These results indicated that supplementary RPFA in cow diets had positive effects on feed intake and milk production, increased concentrations of plasma glucose and serum folates, decreased plasma concentrations of NEFA and BHBA and serum concentration of homocysteine, and improved energy balance and reproductive performance. These data suggest that RPFA improves lactation, energy balance and reproductive performance in a dose-dependent manner. [ABSTRACT FROM AUTHOR]