Junhu Yao

Effect of dietary physically effective fiber on ruminal fermentation and the fatty acid profile of milk in dairy goats

The objective of this experiment was to characterize the relationship among rumen fermentation variables, milk fatty acid profile, and dietary physically effective neutral detergent fiber (peNDF) content in a study that controlled for the potential confounding effects of dissimilar dry matter intake among treatments. Ten multiparous Xinong Saanen dairy goats were divided into 2 groups with 2 ruminally cannulated goats per group. Goats in each group were assigned to 1 of 2 dietary treatments (high and low peNDF) according to a 2×2 crossover design with 2 periods. The peNDF content of alfalfa hay (proportion of neutral detergent fiber retained on an 8.0-mm screen) was 42.1% for the high-peNDF and 14.5% for the low-peNDF group. To ensure similar dry matter intake, each morning the amount of alfalfa hay consumed on the prior day by the high-peNDF group was determined (amount offered minus morning refusals), and this was the amount of hay offered to the low-peNDF group that day. Each adaptation period consisted of 21d, followed by a 9-d sampling period. Dry matter intake and milk production and composition were similar between treatments. Milk energy efficiency increased with low dietary peNDF. Duration of pH below 5.60 was longer for goats fed the low-peNDF ration compared with the high-peNDF ration (4.08 vs. 0.41h/d); however, mean rumen pH (6.05 vs. 6.13) was not different between treatments. Reducing dietary peNDF increased rumen total volatile fatty acids (114.6 vs. 95.1mM) and decreased chewing time (404 vs. 673min/d), but did not affect the ratios of acetate, propionate, and butyrate. The relative abundance of Fibrobacter succinogenes and Ruminococcus flavefaciens increased with reduced dietary peNDF, but Ruminococcus albus proportions were not influenced by treatment. Reducing dietary peNDF decreased the proportion of iso C14:0, iso C15:0, and trans-11 C18:1 in milk fat, whereas the iso C17:0 and trans-10 C18:1 increased. This study demonstrated that low dietary peNDF in dairy goats increases rumen volatile fatty acids, reduces chewing time, and is correlated to the amount of F. succinogenes and R. flavefaciens.

Regulation of Nutritional Metabolism in Transition Dairy Cows: Energy Homeostasis and Health in Response to Post-Ruminal Choline and Methionine.

This study investigated the effects of rumen-protected methionine (RPM) and rumen-protected choline (RPC) on energy balance, postpartum lactation performance, antioxidant capacity and immune response in transition dairy cows. Forty-eight multiparous transition cows were matched and divided into four groups: control, 15 g/d RPC, 15 g/d RPM or 15 g/d RPC + 15 g/d RPM. Diet samples were collected daily before feeding, and blood samples were collected weekly from the jugular vein before morning feeding from 21 days prepartum to 21 days postpartum. Postpartum dry matter intake (DMI) was increased by both additives (P < 0.05), and energy balance values in supplemented cows were improved after parturition (P < 0.05). Both RPC and RPM decreased the plasma concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) (P < 0.05), but increased the plasma levels of glucose, very-low-density lipoprotein (VLDL) and apolipoprotein B100 (ApoB 100, P < 0.05). The supplements improved milk production (P < 0.05), and increased (P < 0.05) or tended to increase (0.05 < P < 0.10) the contents of milk fat and protein. The post-ruminal choline and methionine elevated the blood antioxidant status, as indicated by total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) activity and the vitamin E concentration (P < 0.05), and reduced the plasma malondialdehyde (MDA) level (P < 0.05). Furthermore, RPM and RPC elevated the plasma interleukin 2 (IL-2) concentration and the CD4+/CD8+ T lymphocyte ratio in peripheral blood (P < 0.05). Alternatively, the levels of tumor necrosis factor-α (TNF-α) and IL-6 were decreased by RPM and RPC (P < 0.05). Overall, the regulatory responses of RPC and RPM were highly correlated with time and were more effective in the postpartum cows. The results demonstrated that dietary supplementation with RPC and RPM promoted energy balance by increasing postpartal DMI and regulating hepatic lipid metabolism, improved postpartum lactation performance and enhanced antioxidant capacity and immune function of transition dairy cows.

Subacute ruminal acidosis challenge changed in situ degradability of feedstuffs in dairy goats

This study investigated the effects of wheat-induced subacute ruminal acidosis (SARA) on rumen bacterial populations and in situ degradabilities of NDF, starch, and crude protein of feeds. Four multiparous dairy goats (BW=60±3.3kg) fitted with ruminal cannulas were assigned to a 2×2 crossover design (28-d treatment periods separated by a 7-d washout interval). The treatment diets consisted of 2 levels of cracked wheat: 0 (control, corn based concentrate) and 35% (diet-induced SARA, wheat-based concentrate), with a constant forage- (45% alfalfa hay and 5% corn silage of DM) to-concentrate (50% of DM) ratio. Results indicate that diets with a 35% wheat decreased ruminal pH (6.21 vs. 5.98) and increased the duration (1.13 vs. 4.72h/d) and area (0.12 vs. 0.78 pH × h/d) of ruminal pH below 5.6 and induced SARA. The SARA increased ruminal total volatile fatty acid concentration, from 105.0 to 123.8mM, and decreased the acetate molar proportion (62.8 vs. 56.6mol/100mol) and the acetate-to-propionate ratio (3.5 vs. 2.8). Compared with the control group, SARA decreases the relative abundance of Fibrobacter succinogenes (-59.3%) and Ruminococcus flavefaciens (-68.4%), whereas it increased Succinimonas amylolytica (198.1%) and Ruminobacter amylophilus (125.2%). The SARA decreased 24- and 48-h dry matter (DM) and neutral detergent fiber (NDF) degradabilities of corn silage. The 48-h degradabilities of DM (51.0 vs. 48.2%) and NDF (40.3 vs. 36.0%) in alfalfa hay were not affected by SARA, but the SARA tended to reduce the 24-h DM (49.6 vs. 46.3%) and NDF (37.8 vs. 33.2%) degradabilities. The effective ruminal degradabilities of DM and NDF in alfalfa hay and corn silage were reduced during SARA. In situ degradability parameters of DM and starch of wheat were not affected by SARA, but starch degradability of corn (9.5 vs. 13.3%/h) increased. The SARA reduced in situ 12-h degradabilities of DM and crude protein of soybean meal and extruded soybean without affecting the degradabilities of the other protein supplements (corn gluten meal, cottonseed meal, corn dried distillers grains with solubles, rapeseed meal, and wheat germ meal). These results indicated that the cracked wheat-induced SARA reduced the degradation of NDF in roughages and that of protein in soybean meal (-19.8%) and extruded soy (-18.9%) and increased the starch degradability in corn, due to the increased amylolytic bacteria and decreased cellulolytic bacteria counts in the rumen.

Regulation of pancreatic exocrine secretion in goats: differential effects of short- and long-term duodenal phenylalanine treatment

Four yearling goats (31.2 ± 2.5 kg), surgically fitted with common bile duct reentrant and duodenal catheter, were used in two 4 × 4 Latin square design experiments to investigate the effects of duodenal infusion of phenylalanine for different times on pancreatic exocrine secretion (PES). In experiment 1 (the long-term experiment), goats were duodenally infused with 0, 2, 4 or 8 g/day phenylalanine for 14 day. Pancreatic juice and jugular blood samples were collected over 1-h intervals for 6 h daily from day 11 to day 14 to encompass a 24-h day. In experiment 2 (the short-term experiment), goats were infused with phenylalanine for 10 h continuously at the same infusion rate as experiment 1 after feed deprivation for 24 h repeated every 10 day. Pancreatic juice and blood samples were collected at 0, 1, 2, 4, 6, 8 and 10 h of infusion. The volume and pH of pancreatic juice were measured, and a 5% subsample was composited and frozen until analysis of enzyme activities. Plasma was frozen until analysis of insulin and cholecystokinin (CCK). In experiment 1, pancreatic juice, α-amylase secretion and plasma CCK concentration responded quadratically (p < 0.05), with the top value observed at the 2 g/day phenylalanine. Trypsin secretion had a quadratic response (p < 0.05), with secretion increasing up to 4 g/day phenylalanine and decreasing thereafter. Phenylalanine linearly decreased pancreatic protein and lipase secretion (p < 0.05). The results of correlation analysis showed significant correlations (p < 0.05) between plasma CCK concentration and secretion of α-amylase and trypsin. However, the short-term phenylalanine infusion did not influence (p > 0.05) pancreatic juice, protein, α-amylase, lipase, trypsin secretion and plasma CCK concentration. These results indicate PES of ruminants is stimulated by phenylalanine and is potentially mediated by CCK in the long-term duodenal infusion treatment, but is not influenced by phenylalanine in the short-term duodenal infusion treatment.

Considering choline as methionine precursor, lipoproteins transporter, hepatic promoter and antioxidant agent in dairy cows

During the transition period, fatty liver syndrome may be caused in cows undergo negative energy balance, ketosis or hypocalcemia, retained placenta or mastitis problems. During the transition stage, movement of non-esterified fatty acids (NEFA) increases into blood which declines the hepatic metabolism or reproduction and consequently, lactation performance of dairy cows deteriorates. Most of studies documented that, choline is an essential nutrient which plays a key role to decrease fatty liver, NEFA proportion, improve synthesis of phosphatidylcholine, maintain lactation or physiological function and work as anti-oxidant in the transition period of dairy cows. Also, it has a role in the regulation of homocysteine absorption through betaine metabolite which significantly improves plasma α-tocopherol and interaction among choline, methionine and vitamin E. Many studies reported that, supplementation of rumen protected form of choline during transition time is a sustainable method as rumen protected choline (RPC) perform diverse functions like, increase glucose level or energy balance, fertility or milk production, methyl group metabolism, or signaling of cell methionine expansion or methylation reactions, neurotransmitter synthesis or betaine methylation, increase transport of lipids or lipoproteins efficiency and reduce NEFA or triacylglycerol, clinical or sub clinical mastitis and general morbidity in the transition dairy cows. The purpose of this review is that to elucidate the choline importance and functions in the transition period of dairy cows and deal all morbidity during transition or lactation period. Furthermore, further work is needed to conduct more studies on RPC requirements in dairy cows ration under different feeding conditions and also to elucidate the genetic and molecular mechanisms of choline in ruminants industry.

Relationships between leucine and the pancreatic exocrine function for improving starch digestibility in ruminants

Four Holstein heifers (215 ± 7 kg; means ± SD), fitted with one pancreatic pouch, duodenal re-entrant cannulas, and duodenal infusion catheters, were used in this experiment. In phase 1, the 24-h profile of pancreatic fluid was determined. Pancreatic fluid flow peaked 1h after feeding, but peaks of similar magnitude also occurred before the morning feed, necessitating 24-h collection of pancreatic fluid to estimate daily excretion. In phase 2, the effects of duodenal infusions of 0, 10, 20, or 30 g of leucine on pancreatic fluid flow were determined in a 4 × 4 Latin square design. The leucine was infused for 12h in 2,500 mL of the infusate, and samples of pancreatic fluid and jugular blood were collected in 1-h intervals from the beginning of the infusion for 36 h. The results showed that the secretion rate of pancreatic fluid (mL/h) was significantly higher in 10-g leucine group than the other groups (mL/h). Protein concentration (mg/mL) in pancreatic fluid was elevated proportional to the amount of leucine infused. Leucine infusions increased both the concentration (U/mL) and secretion rate (U/h) of α-amylase. Infusion of 10 g of leucine also increased the secretion rates (U/h) of trypsin, chymotrypsin, and lipase, but did not change their concentrations. No significant effects of leucine infusions on plasma glucose and insulin concentrations were found. The results indicate that leucine could act as a nutrient signal to stimulate α-amylase production and pancreatic exocrine function in dairy heifers.

Dynamics of methanogenesis, ruminal fermentation, and alfalfa degradation during adaptation to monensin supplementation in goats

This study aimed to examine the temporal (hourly within a day and daily over the long term) effects of monensin on CH4 emissions, ruminal fermentation, and in situ alfalfa degradation in dairy goats during dietary monensin supplementation by controlling the confounding effects of feed intake and ambient temperature. Six ruminally cannulated dairy goats were used, and they were housed in environmental chambers and fed a restricted amount of ration throughout the experiment. The experiment included a baseline period of 20 d followed by a treatment period of 55 d with 32 mg of monensin/d. During the whole experiment, CH4 production was measured every 5 d, whereas fermentation characteristics and in situ alfalfa degradation were analyzed every 10 d. The CH4-depressing effect of monensin was time dependent on the duration of treatment, highly effective at d 5 but thereafter decreased gradually until d 55 even though CH4-suppressing effect still remained significant. The decreasing effects of monensin on ruminal acetate proportion and acetate to propionate ratio also faded over days of treatment, and the acetate proportion returned up to the pre-supplementation level on d 50. Monensin supplementation elevated ruminal propionate proportion and decreased the effective ruminal degradability of alfalfa NDF, but both measurements tended to recover over time. The postprandial increase rate of hourly CH4 emissions was reduced, whereas that of propionate proportion was enhanced by monensin supplementation. However, the postprandial responses to monensin in CH4 emission rates, ruminal VFA profiles, and in situ degradation kinetics declined with both hours after feeding and days of treatment. Our results suggest that the CH4-suppressing effect of monensin supplementation in goats was attributed to reductions in both ruminal feed degradation and acetate to propionate ratio, but those reductions faded with time, hours after feeding, and days of treatment.

Folate promotes S-adenosyl methionine reactions and the microbial methylation cycle and boosts ruminants production and reproduction

Folate has gained significant attention due to its vital role in biological methylation and epigenetic machinery. Folate, or vitamin (B9), is only produced through a de novo mechanism by plants and micro-organisms in the rumen of mature animals. Although limited research has been conducted on folate in ruminants, it has been noted that ruminal synthesis could not maintain folate levels in high yielding dairy animals. Folate has an essential role in one-carbon metabolism and is a strong antiproliferative agent. Folate increases DNA stability, being crucial for DNA synthesis and repair, the methylation cycle, and preventing oxidation of DNA by free radicals. Folate is also critical for cell division, metabolism of proteins, synthesis of purine and pyrimidine, and increasing the de novo delivery of methyl groups and S-adenosylmethionine. However, in ruminants, metabolism of B12 and B9 vitamins are closely connected and utilization of folate by cells is significantly affected by B12 vitamin concentration. Supplementation of folate through diet, particularly in early lactation, enhanced metabolic efficiency, lactational performance, and nutritional quality of milk. Impaired absorption, oxidative degradation, or deficient supply of folate in ruminants affects DNA stability, cell division, homocysteine remethylation to methionine, de novo synthesis of S-adenosylmethionine, and increases DNA hypomethylation, uracil misincorporation into DNA, chromosomal damage, abnormal cell growth, oxidative species, premature birth, low calf weight, placental tube defects, and decreases production and reproduction of ruminant animals. However, more studies are needed to overcome these problems and reduce enormous dietary supplement waste and impaired absorption of folate in ruminants. This review was aimed to highlight the vital role of folic acid in ruminants performance.

Effects of dietary leucine and phenylalanine on pancreas development, enzyme activity, and relative gene expression in milk-fed Holstein dairy calves

This study aimed to investigate the effect of dietary supplementation with leucine and phenylalanine on pancreas development, enzyme activity, and related gene expression in male Holstein calves. Twenty male Holstein calves [1 d of age, 38 ± 3 kg of body weight (BW)] were randomly assigned to 1 of the following 4 treatment groups with 5 calves in each group: control, leucine supplementation (1.435 g/L of milk), phenylalanine supplementation (0.725 g/L of milk), and leucine and phenylalanine (1.435 + 0.725 g/L of milk). The diets were made isonitrogenous with the inclusion of alanine in each respective treatment. The feeding trial lasted for 8 wk, including 1 wk for adaption and 7 wk for the feeding experiment. Leucine tended to increase the concentration of total pancreatic protein (mg/kg of BW). Phenylalanine increased the concentrations of plasma insulin, cholecystokinin, and pancreatic DNA (mg/g) and the expression of trypsin gene but decreased the pancreatic protein:DNA ratio and tended to decrease the pancreas weight (g/kg of BW). No differences were observed in total pancreatic DNA (mg/pancreas and mg/kg of BW), pancreatic protein (mg/pancreas), or activities of α-amylase, trypsin, and lipase. The relative expression levels of the genes encoding α-amylase and lipase did not differ among the 4 groups. The supplementation of both leucine and phenylalanine showed an interaction on the pancreas weight (g and g/kg of BW) and a tendency of an interaction on the pancreatic protein concentration (mg/g of pancreas and mg/kg of BW) and the plasma glucose concentration. Leucine tended to increase the size of the pancreatic cells, whereas phenylalanine tended to increase the number of pancreatic cells. However, neither AA affected the activities of the pancreatic enzymes of the calves. These results indicate that leucine and phenylalanine supplementation in milk-fed Holstein calves differentially affect pancreatic growth and development.

Duodenal infusions of isoleucine influence pancreatic exocrine function in dairy heifers

ABSTRACT Four healthy Holstein heifers (235 ± 12 kg) fitted with duodenal and pancreatic cannulas were used to investigate infusion of isoleucine (Ile) on the pancreatic exocrine function in a 4 × 4 Latin square design. Three doses of Ile, 10, 20 and 30 g in 2500 ml water, respectively, were infused into the duodenum over a period of 12 h in Experiment (Exp) 1 and over 10 d in Exp 2. Hourly pancreatic juice and jugular blood were taken during the infusion period in Exp 1, and the blood samples were taken in 2-h intervals over the last 2 d in Exp 2. Compared with no Ile infusion, the Ile infusions in both experiments increased the concentration and secretion rate of the protein, activity of ɑ-amylase and trypsin and plasma cholecystokinin. The secretion rate of ɑ-amylase and the activity of trypsin linearly increased with the Ile doses. The pancreatic juice secretion linearly increased with Ile in Exp 2 but not in Exp 1. Isoleucine linearly increased plasma insulin in Exp 1, but not in Exp 2. No effects of Ile on pH of pancreatic juice, the activity of chymotrypsin and lipase and plasma glucose were found. In conclusion, duodenal Ile infusion could increase the pancreatic exocrine function of Holstein heifers, especially ɑ-amylase, and the increment appeared to be dose and time dependent.