Rumen Total Volatile Fatty Acids Research Articles

Rumen Metabolite and Haematological Characteristics of Bunaji Bulls fed Diet Containing Raw or Parboiled Rice Offal as Energy Source

A study was conducted to evaluate the effect of feeding raw or parboiled rice offal diet on rumen metabolite and haematological characteristics of bulls.20 Bunaji bulls aged 2-3 years with live weight 210- 249kg were allotted to five dietary treatments having Four bulls per treatment in a 2x2 factorial arrangement with a common control. Feeding trials lasted 90 days. Rumen fluid was collected at 0, 2, 4 and 6 hrs intervals to determine the rumen pH, rumen ammonia nitrogen (RAN) and rumen total volatile fatty acid (TVFA) for all the bulls. Blood sample were obtained at the beginning, middle and end of the feeding trial to determine haematological parameters. A concentrate and basal diets of Digitaria smutsii were offered at 2% body weight. The CP contents of the experimental diets vary between 19.69 and 20.44% while the ME ranged from 10.86 to 11.16MJ/kg DM. Rumen parameters were not significantly (P>0.05) affected by rice type but significantly (P 0.05), but differed (P 0.05) on rumen pH and TVFA at different sampling time. However, significant (P 0.05) with rice offal type. Blood glucose was however significant (P 0.05) difference for all the haematological parameters measured for Animals on varying levels of inclusion of raw or parboiled rice offal. It was concluded from this study that raw or parboiled rice offal may be used to replace up to 30% of maize offal as source of energy in the diet of Bunaji bulls without any detrimental effect on rumen metabolite and haematological composition of the bulls. Hence it can be adopted by farmers. Keyword: Bunaji bull, haematological composition, rice offal, Rumen metabolite.

Effects of Chinese herbal medicine on plasma glucose, protein and energy metabolism in sheep

BackgroundThe use of antibiotics in animal diets is facing negative feedback due to the hidden danger of drug residues to human health. Traditional Chinese herbal medicine has been used to replace antibiotics in the past two decades and played an increasingly important role in livestock production. The present study was carried out to assess the feeding effects of a traditional nourishing Chinese herbal medicine mixture on kinetics of plasma glucose, protein and energy metabolism in sheep. Ruminal fermentation characteristics were also determined.MethodsFour sheep were fed on either mixed hay (MH-diet) or MH-diet supplemented with 2% of Chinese herbal medicine (mixture of Astragalus root, Angelica root and Atractylodes rhizome; CHM-diet) over two 35-day periods using a crossover design. The turnover rate of plasma glucose was measured with an isotope dilution method using [U-13C]glucose. The rates of plasma leucine turnover and leucine oxidation, whole body protein synthesis (WBPS) and metabolic heat production were measured using the [1-13C]leucine dilution and open circuit calorimetry.ResultsBody weight gain of sheep was higher (P = 0.03) for CHM-diet than for MH-diet. Rumen pH was lower (P = 0.02), concentration of rumen total volatile fatty acid tended to be higher (P = 0.05) and acetate was higher (P = 0.04) for CHM-diet than for MH-diet. Turnover rates of plasma glucose and leucine did not differ between diets. Oxidation rate of leucine tended to be higher (P = 0.06) for CHM-diet than for MH-diet, but the WBPS did not differ between diets. Metabolic heat production tended to be greater (P = 0.05) for CHM-diet than for MH-diet.ConclusionsThe sheep fed on CHM-diet had a higher body weight gain and showed positive impacts on rumen fermentation and energy metabolism without resulting in any adverse response. Therefore, these results suggested that the Chinese herbal medicine mixture should be considered as a potential feed additive for sheep.

Effects of feed additives on rumen and blood profiles during a starch and fructose challenge

We evaluated the effect of feed additives on the risk of ruminal acidosis in Holstein heifers (n=40) fed starch and fructose in a challenge study. Heifers were randomly allocated to feed additive groups (n=8 heifers/group): (1) control (no additives); (2) virginiamycin (VM); (3) monensin + tylosin (MT); (4) monensin + live yeast (MLY); and (5) sodium bicarbonate + magnesium oxide (BUF). Heifers were fed 2.5% of body weight (BW) dry matter intake (DMI) per day of a total mixed ration (62:38 forage:concentrate) and feed additives for a 20-d adaptation period. Fructose (0.1% of BW/d) was included for the last 10d of the adaptation period. On d 21, heifers were fed to target a DMI of 1.0% of BW of wheat, fructose at 0.2% of BW, and their feed additives. Rumen fluid samples obtained by stomach tube and blood samples were collected weekly as well as during a 3.6-h period on challenge day (d 21). Virginiamycin and BUF groups maintained a consistently high DMI across the 20-d adaptation period. The MLY heifers had low DMI of the challenge ration. Average daily gain and feed conversion ratio were not affected by feed additives. All rumen and plasma measures changed weekly over adaptation and over the challenge sampling period with the exception of rumen total lactate and histamine concentrations, plasma oxidative stress index, and ceruloplasmin. Substantial within- and between-group variation was observed in rumen and plasma profiles at challenge sampling. No significant group changes were observed in rumen total volatile fatty acids, propionate, acetate-to-propionate ratio, isobutyrate, caproate, isovalerate, total lactate, d- and l-lactate, and pH measures on challenge day. Acetate concentration was increased in the BUF and control groups on challenge day. Butyrate concentration was lower in the MLY and MT groups compared with other groups at challenge. Valerate concentrations were lowest in the control, VM, and BUF groups and lactate concentrations were numerically lower in the MLY, VM, and BUF groups. Total lactate concentrations were >10mM for each group throughout the challenge. Ammonia concentrations were lower in the MLY and MT groups. Histamine concentrations were decreased in MLY and increased in the VM and BUF groups. Plasma oxidative stress measures were not influenced by feed additives weekly or on challenge day, except for an increase in biological antioxidant potential in the control, VM, and MT groups on challenge day. Despite the large within-animal variation, all feed additives modified rumen function and may influence the risk of acidosis by different mechanisms; however, none stabilized the rumen in all heifers.

Effects of 2-hydroxy-4(methylthio) butanoic acid isopropyl ester on rumen fermentation in cashmere goats

The impact of dietary 2-hydroxy-4-(methylthio) butyric acid isopropyl ester (HMBi) on rumen fermentation in cashmere goats was investigated to determine the effect of this ester on cashmere production. Four healthy castrated Liaoning cashmere goats with permanent rumen cannulas were assayed for four periods. In each period, goats were fed a different diet: control diet (containing 0% MetaSmart (an HMBi product)), diet I (containing 0.85% MetaSmart), diet II (containing 1.27% MetaSmart) or diet III (containing 1.70% MetaSmart). Rumen pH, ammonia-N concentration, volatile fatty acid (VFA) concentrations and total protein concentration were determined after feeding in each period. Results showed that rumen pH significantly increased and rumen ammonia-N concentration significantly decreased when the diet was supplemented with 0.85%, 1.27% and 1.70% MetaSmart. Diets with 1.27% and 1.70% MetaSmart increased rumen total VFA concentration, and 3 hours post feeding all three HMBi diets increased acetic acid concentration. Rumen total protein concentration significantly increased in the goats fed 1.27% or 1.70% MetaSmart. Thus, diets supplemented with HMBi significantly affected rumen pH, ammonia-N concentration, VFA concentrations and total protein content. Dietary HMBi can promote rumen fermentation in cashmere goats.

Plasma Acetate Turnover Rate and Rumen Fermentation Characteristics in Sheep Fed Rice Straw Supplemented with Soybean Meal

The present experiment was conducted to assess the effects of rice straw supplemented with soybean meal (RSS-diet) on turnover rate of plasma acetate using an isotope dilution method in sheep. Rumen fermentation characteristics and nitrogen (N) balance were also determined. Four sheep were assigned to two dietary treatments including either a RSS-diet or mixed hay (MH-diet). The experiment was performed by a crossover design with two 24 day periods. On day 24 of each dietary period the isotope dilution method of [1- 13 C]Na acetate was carried out as the primed-continuous infusion to determine the plasma acetate turnover rate. Nitrogen intake and N retention did not differ between diets, while N digestibility was higher (P = 0.004) for the RSS-diet than the MH-diet. Concentrations of rumen total volatile fatty acid (VFA) and acetate did not differ between diets, and those of other individual VFA were higher (P < 0.05) for the RSS-diet than the MHdiet. Concentration and turnover rate of plasma acetate did not differ between dietary treatments. From the present results it could be concluded that rice straw supplemented with soybean meal as high energy protein source showed the comparable performance to mixed hay on plasma acetate turnover rate, and enhanced performance over mixed hay on digestive functions in sheep.

Nitrogen metabolism and milk production in dairy cows fed semi‐restricted amounts of ryegrass–legume silage with birdsfoot trefoil (Lotus corniculatus L.) or white clover (Trifolium repens L.)

AbstractIn change‐over trials, mid‐lactation dairy cows were fed concentrate‐supplemented, isonitrogenous and isofibrous perennial ryegrass–legume silage diets that satisfied energy requirements but were suboptimal with respect to metabolizable protein supply. Legumes were either birdsfoot trefoil with low levels of condensed tannins (typical for hemiboreal conditions), or white clover. Averaged over two experimental years, birdsfoot trefoil–based silage resulted in lower digestibility (P &lt; 0·001) of dry matter (50 g kg−1), organic matter (52 g kg−1), neutral detergent fibre (120 g kg−1) and nitrogen (24 g kg−1) and lower rumen total volatile fatty acid concentration (7 mm; P = 0·009). Milk protein yield was 36 g d−1 higher with birdsfoot trefoil silage (P = 0·002), while raw milk yield tended to be 0·8 kg d−1 higher (P = 0·06). Rumen ammonia concentration was similar between diets, but milk urea concentration (P &lt; 0·001), urinary urea excretion (P = 0·002) and faecal‐N proportion (P = 0·001) were higher with birdsfoot trefoil silage. The results suggest that grass–birdsfoot trefoil silage produced in hemiboreal areas exhibits a protein‐sparing effect in dairy rations, despite a low condensed tannin content that is further diluted by companion grasses and ration concentrate proportion.

Morning vs. evening feed delivery for lactating dairy cows

Nikkhah, A., Furedi, C. J., Kennedy, A. D., Scott, S. L., Wittenberg, K. M. Crow, G. H. and Plaizier, J. C. 2011. Morning vs. evening feed delivery for lactating dairy cows. Can. J. Anim. Sci. 91: 113–122. A study was conducted to investigate the effects of changing feed delivery time from morning (0900) to evening (2100) on feed intake, diurnal feed intake patterns, digestion, rumen fermentation, milk production and composition, as well as on several blood metabolites. Eight (four ruminally cannulated) lactating Holstein cows, consisting of four primiparous and four multiparous cows, were used in the study. The change in the time of feed delivery increased the proportion of feed consumed within 3 h of feed delivery in all cows (54.7 vs. 46.3±4.1%, means±SE, P=0.05), but increased daily dry matter intake only in primiparous cows (18.5 vs. 20.4±0.7 kg d−1, P=0.05). Average daily concentrations of blood glucose, lactate, urea and β-hydroxybutyrate (BHBA) as well as rumen pH and concentrations of volatile fatty acids (VFA) were not affected by feed delivery time. However, rumen pH was lower (P&lt;0.05), at 5 and 6 h after feed delivery, while total rumen VFA and acetate were higher (P&lt;0.05) only at 6 h after feed delivery in cows fed in the evening. Also, compared with feed delivery at 0900, feeding cows at 2100 resulted in lower (P&lt;0.05) blood glucose and urea at 2 h after feed delivery, and increased BHBA (P&lt;0.05) at 4 and 6 h after feed delivery. Cows fed at 2100 tended to produce more milk fat than those fed at 0900 (1.11 vs. 0.97±0.07 kg d−1, P=0.08). Milk yield and milk protein were not affected by the time of feed delivery. Changing the feed delivery time from morning to evening increased apparent total tract digestibility of dry matter, nitrogen, and neutral detergent fibre. The results of this study suggest that changing time of feed delivery from 0900 to 2100 increases feed consumption within 3 h after this delivery and rumen fermentation within 6 h after this delivery, changes diurnal patterns of glucose, urea and BHBA in peripheral blood, tends to increase milk fat, and increases nutrient digestibilities.

Replacing corn with glycerol in diets for transition dairy cows

Expansion of the biofuels industry has increased the availability of glycerol as an alternative feed for dairy cows. The objective of this study was to determine the effects of glycerol on feed intake, milk production, rumen volatile fatty acids, and metabolic parameters in transition dairy cows. Multiparous Holstein cows were fed diets containing either high-moisture corn (n=11) or glycerol (n=12) from −28 to +56 d relative to calving. Glycerol was included at 11.5 and 10.8% of the ration dry matter for the pre- and postpartum diets, respectively. Prepartum feed intake was not changed by glycerol feeding (14.9 vs. 14.6 kg/d, control vs. glycerol) nor did postpartum feed intake differ (19.8 vs. 20.7 kg/d, control vs. glycerol). Overall milk yield did not differ (35.8 vs. 37 kg/d, control vs. glycerol) and milk composition, milk urea nitrogen, somatic cells, and energy balance were not different with glycerol feeding. Blood glucose content was decreased in cows fed glycerol during the prepartum period (59.1 vs. 53.4 mg/dL), and β-hydroxybutyrate concentration was increased (0.58 vs. 0.82 mmol/L, control vs. glycerol). Concentrations of blood nonesterified fatty acids did not differ between the treatment groups, and no response to glycerol for blood metabolites during the postpartum period was observed. Total rumen volatile fatty acid concentrations (mmol/L) did not differ between treatments, but proportions of rumen propionate and butyrate were greater for cows fed glycerol (22.7 vs. 28.6% of propionate, control vs. glycerol; and 11.5 vs. 15.3% of butyrate, control vs. glycerol) at the expense of acetate (61.4 vs. 51.5%, control vs. glycerol). These data indicate that glycerol is a suitable replacement for corn grain in diets for transition dairy cows.

Effects of Persimmon (Diospros kaki L.) Vinegar as a Dietary Supplement on Feed Intake, Digestibility, and Ruminal Fermentation Indices in Sheep

This study estimated the effect of fermented persimmon (Diospros kaki L.) extract (FPE) supplement on feed intake, digestibility, nitrogen (N) balance, and rumen fermentation characteristics in sheep. Five male sheep (Corriedale×Polwarth) with average body weight of 48.6±1.3 kg were housed in metabolism crates and assigned to a 5×5 Latin square design with five consecutive 20-d periods which consisted of 14-d adaptation and 6-d data collection. The sheep were fed ad libitum a diet containing concentrate and rice straw (3:7). The five treatments were FPE supplemented at 0 (Control), 5, 10, 20, and 30 g/kg of concentrate. Intakes of dry matter (DM, p<0.01), organic matter (OM, p<0.01), neutral detergent fiber (NDF, p<0.05), acid detergent fiber (ADF, p<0.05), and nitrogen-free extract (NFE, p<0.01) increased quadratically with increasing intake of FPE supplement and maximized (p<0.05) at 10 g/kg FPE. The digestibilities of DM (p<0.05), OM (p<0.05), crude protein (p<0.01), and NFE (p<0.01) increased quadratically with increasing amount of FPE supplement, and sheep fed 5 and 10 g/kg diets had greater (p<0.05) DM, OM, and NFE digestibilites than the Control treatment. By increasing FPE supplement concentration, N intake (p<0.01) and fecal N (p<0.05) increased linearly, whereas retained N (p<0.05) and retained N ratio (p<0.05) increased quadratically. The retained N was maximized (p<0.05) in sheep fed 5 and 10 g/kg diets. The mean rumen pH was not affected by FPE supplement, but there was a quadratic increase (p<0.05) of mean rumen ammonia N concentration and a linear increase (p<0.01) in mean rumen total volatile fatty acid (VFA) and acetate concentrations. The mean concentration of rumen propionate in sheep fed all FPE supplemented diets was greater (p<0.05) than the Control, but the mean ratios of rumen acetate to propionate in sheep fed 5 and 10 g/kg diets were lower (p<0.05) than that of Control sheep. In conclusion, FPE supplemented at 5-10 g/kg of concentrate improved feed intake, the digestibilites of OM and NFE, N metabolism, and rumen fermentation indices of sheep. (Key Words : Fermented Persimmon Extract, Digestibility, Nitrogen Balance, Sheep)

Carbohydrate source and protein degradability alter lactation, ruminal, and blood measures

Thirty-eight lactating dairy cows including 6 ruminally cannulated cows were used in a feeding study to assess effects of feed sources that differed in dietary nonfiber carbohydrate (NFC) composition and ruminal degradability of dietary protein (RDP) on production, ruminal, and plasma measures. The design was a partially balanced, incomplete Latin square with three 21-d periods and a 3 × 2 factorial arrangement of treatments. Samples and data were collected in the last 7 d of each period. Feed sources that differed in NFC profile were dry ground corn (GC; starch), dried citrus pulp (DCP; sugar and pectins), and sucrose+molasses (SM; sugar). Dietary RDP was altered by providing CP with soybean meal (+RDP) or substituting a heat-treated expeller soybean product for a portion of the soybean meal (−RDP). Diets were formulated to be isonitrogenous and similar in NFC concentration. Cows consuming GC had the greatest milk urea nitrogen and milk protein percentage and yield, tended to have the greatest dry matter intake, but had a lesser milk fat percentage compared with cows consuming DCP and SM. Sucrose+molasses diets supported greater dry matter intake, milk protein yield, and 3.5% fat- and protein-corrected milk yield than did DCP diets. On −RDP diets, milk protein percentage was less and milk urea nitrogen and protein yield tended to be less than for +RDP diets. Dry ground corn diverged from DCP and SM in the effect of NFC × RDP, with cows consuming GC having lesser milk yield, 3.5% fat- and protein-corrected milk yield, and efficiency with −RDP as compared with +RDP, whereas these production measures were greater with −RDP than +RDP for cows consuming DCP and SM. In contrast, in situ NDF digestibility at 30h for GC and SM was greater for −RDP as compared with +RDP, but the reverse was true for DCP. The lowest ruminal pH detected by 6h postfeeding was also influenced by the interaction of NFC × RDP, with cows consuming SM having a lower pH with +RDP than with −RDP and cows consuming DCP having a similar pH on either RDP treatment. Total rumen volatile fatty acid concentrations did not differ among diets, but acetate molar percent was greater for DCP than for SM, and GC had the lowest molar percent for butyrate and valerate and greatest branched-chain volatile fatty acid concentration. Valerate molar percent and NH3 concentration tended to be greater with +RDP than with −RDP. Plasma glucose and insulin were both greater in cows receiving SM than in those receiving DCP. Protein degradability, NFC source, and their interactions affected lactation, ruminal, and blood measures, suggesting that these dietary factors warrant further consideration in diet formulation.

Effects of replacement of alfalfa by inflorescences of Yucca carnerosana in the diet on performance of growing goats

The chemical composition, in vitro organic matter digestibility (OMD), and energy content of inflorescences of Yucca carnerosana, an endemic species to the Chihuahuan desert of Northern Mexico were evaluated. The effects of addition of air-dried inflorescences of Y. carnerosana, replacing alfalfa in the diet of growing goats were also studied. Forty growing female crossbred goats (native × dairy goats; 12.4 ± 2.1 kg; 3 months of age) were assigned to five equal groups in a completely randomized design. Zero (T0), 25 (T25), 50 (T50), 75 (T75) and 100% (T100) inflorescences of Y. carnerosana were added for alfalfa replacement (300 g kg − 1 of the diet) in a completely mixed diet based on corn grain and soybean meal. Values of nutritional parameters for inflorescences of Y. carnerosana were: in vitro OMD, 701 g kg − 1 ; crude protein, 130 g kg − 1 ; metabolizable energy, 9.56 MJ kg − 1 DM. Average daily gain (ADG) (range 90 ± 6 to 125 ± 21 g) and dry matter intake (DMI; 471 ± 72 to 554 ± 44 g day − 1 ) were similar among dietary groups. Feed conversion ratio (FCR, DMI/ADG) differed ( P < 0.05) between T0 (4.0 ± 0.4 g g − 1 ) and T75 (5.7 ± 1.3 g g − 1 ) and T100 (6.2 ± 0.4 g g − 1 ). Rumen total volatile fatty acid (VFA) concentrations did not differ between treatment groups (range 60.7 to 68.7 mM, averaged over 3 sampling times), but proportions of acetate was lower ( P < 0.05) in T75 and T100 compared with other dietary treatments. Overall molar proportion of propionate was higher ( P < 0.05) in T100 than other dietary treatments. Goats fed T0 had higher ( P < 0.05) levels of blood glucose, urea and cholesterol than animals on the other dietary treatments. It was concluded that 50% DM of alfalfa hay in the diet of goats can be safely replaced with inflorescences of Y. carnerosana without adverse effects on their growth performance.

Effect of feeding forest foliages, rice straw and concentrate-based total mixed ration on nutrient utilization and growth in mithun ( Bos frontalis)

The study aimed to evaluate the effect of feeding Borrena hirticulata (BH), Ficus hirta (FH), rice straw (RS) and concentrate-based total mixed ration (TMR) on nutrient utilization, rumen fermentation and growth in mithun. Growing male mithun calves were randomly allotted to 2 feeding groups (6 in each), TMR 1 and TMR 2. The TMRs consisted of RS 300 g kg − 1 , concentrate 400 g kg − 1 and BH 300 g kg − 1 (TMR 1) or FH 300 g kg − 1 (TMR 2) on a dry matter (DM) basis. Both TMRs were fed ad libitum to the animals for 121 d and a digestibility study was conducted during the last 7 d of the experiment. To assess rumen fermentation, rumen fluid was collected at 2 h interval for 24 h. Apparent digestibility of DM, crude protein (CP) and crude fibre (CF) did not differ significantly between the TMRs. Nevertheless, apparent digestibility of ether extract was found to be significantly ( P < 0.01) greater in TMR 2 (0.59) compared to TMR 1 (0.54). Body weight gain (BWG; g d − 1 ), DM intake (kg d − 1 ), CP intake (g d − 1 ) and feed efficiency (kg feed kg − 1 gain) were found to be significantly ( P < 0.05) greater in TMR 1 (548, 5.14, 713 and 9.28) compared to TMR 2 (496, 4.91, 703 and 10.03). An insignificant positive association ( r = 0.35) between DM intake and BWG, but a significant ( P < 0.01) positive association ( r = 0.74) between CP intake and BWG were evident. Rumen pH (5.71 to 7.18) and ammonia-nitrogen (8.0 to 25.0 mg/dl) did not differ significantly between the TMRs, but differed significantly ( P < 0.01) at different h post-feeding. In contrast, rumen total volatile fatty acid (42 to 105 mM) and total nitrogen (40.4 to 90.3 mg/dl) differed significantly ( P < 0.05) between the TMRs and at different h post-feeding. The study revealed that BH, FH, RS and concentrate-based TMRs may be fed to mithun for satisfactory growth.

Nutrient Utilization of Differing Forage-to-Concentrate Ratios by Growing Holstein Heifers

Traditionally, high-forage, low-concentrate diets fed ad libitum have been the primary system of feeding dairy heifers. However, high-concentrate diets can be fed at restricted intakes to reach desired rates of gain and increase nutrient efficiency. A total mixed ration containing high corn silage (CS; HCS: 77% CS, 23% concentrate) or low CS (LCS: 67% concentrate, 33% CS) was fed at restricted intakes in 2 trials to evaluate nutrient utilization by growing heifers. In the first trial, 4 ruminally cannulated heifers (298±16kg of body weight) were fed to study differences in rumen pH, volatile fatty acid and ammonia concentrations, and mass of rumen contents. In situ determinations were made on the total mixed ration and CS. Low CS rations were digested more rapidly in situ when compared with HCS (4.5 vs. 2.3±0.3%/h), and no differences were observed in CS digestibility when incubated in the rumen of heifers fed either ration. Mean rumen pH tended to be lower for LCS than for HCS (5.9 vs. 6.2±0.1). Individual and total rumen volatile fatty acid concentrations and rumen ammonia concentration were not different between treatments. Total mass of rumen contents was lower for LCS. In the second trial, four 6-mo-old heifers (172±14kg of body weight) and four 12-mo-old heifers (337±10kg of body weight) were used. Digestibility of dry matter was greater for the LCS than the HCS diet in both age groups (76.3 vs. 71.1% for 12-mo-old heifers; 71.4 vs. 68.9% for 6-mo-old heifers). Apparent digestibility of N was not different between treatments; however, retained N was higher for the LCS diets for both age groups. Fecal output was significantly reduced in the LCS diets for both age groups. Feeding low-forage, high-concentrate diets to growing dairy heifers at restricted intakes, although more highly digestible, resulted in few significant differences in rumen fermentation patterns and lower fecal output.

Effects of Chop Length of Alfalfa and Corn Silage on Milk Production and Rumen Fermentation of Dairy Cows

Effects of chop length (shorter=10mm or longer=19mm) of alfalfa silage and corn silage were determined in 16 midlactation Holstein cows using a 4×4 Latin square design with a 2×2 arrangement of treatments. Experimental periods were 21 d long and consisted of 14 d of adaptation and 7 d of sampling. Cows received total mixed ration containing (dry matter basis) 44.0% barley grain-based energy supplement, 12.6% protein supplement, and 21.7% longer chop or shorter chop alfalfa silage and 21.7% longer chop or shorter chop corn silage. Reducing the chop length of alfalfa silage and corn silage reduced the average geometric particle length from 14.4 to 11.0mm and from 14.2 to 10.4mm, respectively. Reducing the chop length of both silages reduced the proportion of the diets retained by the 8-and 19-mm screen of the Penn State Particle Separator from 55.0 to 46.0% of dry matter. Reducing the alfalfa chop length increased total rumen volatile fatty acids at 4 to 5h after feeding but did not affect rumen pH at 4 to 5h after feeding, feed intake, and milk production. Reducing the corn silage chop length increased dry matter intake from 22.3 to 23.2kg/d, increased rumen pH at 4 to 5h after feeding from 6.12 to 6.20, but did not alter rumen volatile fatty acids at 4 to 5h after feeding or milk production. Daily milk yield, milk fat percentage, and milk protein percentage averaged 38.2kg/d, 2.62%, and 3.29%, respectively, across all diets. The low milk fat percentages suggest that all diets induced subacute ruminal acidosis (SARA), whereas the rumen pH did not indicate SARA. This discrepancy could be due to a difference in the time of rumen pH measurement and the time of the lowest rumen pH. Hence, the pH data need to be interpreted with caution. Diets could have induced SARA, because for all experimental diets the content of forage neutral detergent fiber was lower than recommended for barley grain-based diets.

Effects of Barley Silage Chop Length on Productivity and Rumen Conditions of Lactating Dairy Cows Fed a Total Mixed Ration

Barley silage, cut at the early dough stage, was chopped long (19mm) or short (10mm), ensiled, and incorporated into total mixed rations (TMR). The TMR contained (dry matter [DM] basis) either 58.0 or 41.4% concentrate and either short- or long-chopped barley silage. Reducing chop length of barley silage decreased the proportion (asis basis) of TMR particles retained by the 8- and 19-mm screens of the Penn State Particle Separator (PSPS) from 66.9 to 52.7% in the high concentrate TMR and from 74.8 to 60.9% in the low concentrate TMR. Chop length reduction decreased dietary physically effective fiber, calculated as the NDF retained by the 8- and 19-mm screens of the PSPS, from 29.2 to 25.2% DM in the high concentrate TMR and from 34.9 to 30.6% DM in the low concentrate TMR. Reduction in chop length did not affect rumen pH, total rumen volatile fatty acids, milk yield, and milk composition, but increased DM intake from 19.4 to 20.1 kg/d at the high level of concentrate and from 16.9 to 17.7 kg/d at the low level of concentrate and increased rumen propionate. Increasing the concentrate inclusion rate reduced rumen pH from 6.52 to 6.35, did not affect total volatile fatty acids, reduced the acetate-to-propionate ratio from 3.1 to 2.7, increased milk yield from 28.7 to 31.3 kg/d, reduced milk fat content from 3.48 to 2.94%, and increased milk protein content from 3.11 to 3.27% across chop lengths.

Digestibilidade de nutrientes em dietas de bovinos contendo uréia ou amiréia em substituição ao farelo de soja

O objetivo deste trabalho foi avaliar efeitos da substituição do farelo de soja por uréia ou amiréia na digestibilidade de nutrientes e alguns parâmetros ruminais em bovinos. Seis novilhos da raça Nelore, com massa média inicial de 420 kg, foram utilizados em um delineamento de quadrado latino 3x3 duplicado. O farelo de soja foi utilizado em uma dieta deficiente em proteína degradável no rúmen, e a uréia e amiréia, em uma dieta adequada em proteína degradável no rúmen. O bagaço de cana-de-açúcar in natura foi a única fonte de volumoso (20% da matéria seca). O farelo de soja promoveu menor (P&lt;0,05) consumo de matéria seca comparado aos tratamentos com uréia e amiréia. A digestibilidade da matéria seca, matéria orgânica, carboidratos não fibrosos, extrato etéreo e proteína bruta não diferiram (P&gt;0,05) entre os tratamentos. A digestibilidade da fibra em detergente ácido e fibra em detergente neutro foi superior (P&lt;0,05) nas dietas contendo uréia e amiréia. Não houve efeito de tratamento e da interação tratamento x horários (P&gt;0,05) nos valores de pH, ácidos graxos voláteis total, acetato, propionato, butirato e relação acetato:propionato do fluido ruminal. Observou-se maior (P&lt;0,05) concentração molar de valerato, isobutirato e isovalerato no tratamento com farelo de soja, não havendo diferença (P&gt;0,05) entre os tratamentos com uréia e amiréia. A substituição total do farelo de soja por uréia ou amiréia, ajustando a proteína degradável no rúmen na dieta de bovinos de corte, é viável.

Growth and metabolic responses of Holstein calves fed broiler litter-based diets supplemented with l-carnitine

Thirty-nine growing Holstein calves (150.1±5.5 kg) were used to determine the effects of adding 3-hydroxy-4-N-trimethylaminobutyric acid ( l-carnitine) to diets containing excess crude protein, derived primarily from poultry litter, on growth performance and blood and rumen metabolites. Calves were blocked by body weight (BW) and fed one of the three experimental diets: (1) protein control diet (PC; 17.3% crude protein (CP)), 46.5% corn–soybean meal, 53.5% cottonseed hulls-hay, (2) broiler litter (BL; 22.7% CP), 55% broiler litter, 23% corn and soybean meal, 22% cottonseed hulls-hay, and (3) diet 2+250 ppm l-carnitine (BL+C). Calves were catheterized and intravenous (i.v.) glucose tolerance tests (IVGTTs) were conducted on the final day of the experiment. Mean dry matter intake, average daily gain (ADG), and gain:feed ratio through 42 days were higher ( P<0.05) in calves fed PC compared with those fed BL and BL+C. Calves fed supplemental l-carnitine had an 8% higher ( P=0.003) efficiency of feed conversion. Total rumen volatile fatty acid (VFA) concentrations were higher ( P=0.02) in calves fed the PC compared with those fed the two BL diets (58.2 versus 49.7 mM); however, supplemental l-carnitine did not alter VFA concentrations in calves fed BL. Plasma ammonia N did not differ among treatments. Plasma urea N concentrations were lower ( P<0.01) in calves fed the PC, compared with those fed the BL diets, on both days 21 and 42 of the study. Although similar at day 21, plasma urea N concentrations in samples collected at day 42 were lower ( P=0.01) in calves fed BL+C compared with those fed BL (15.22 versus 19.15 mM). Both plasma glucose concentrations and glucose clearance rate were higher ( P<0.05) in calves fed the PC compared with those fed the broiler litter diets. Supplemental l-carnitine did not affect blood glucose concentrations or glucose clearance rate in calves fed diets containing broiler litter. Results suggest that supplemental l-carnitine may improve performance of calves fed excess levels of soluble protein.

Effect of virginiamycin and sodium bicarbonate on milk production, milk composition and metabolism of dairy cows fed high levels of concentrates

Milk production and composition were measured for 63 days in 153 Holstein–Friesian cows offered either 7, 10 or 13 kg/day (as fed) of a rolled, 74% barley/26% lupin grain mixture together with either no feed additive, 300 mg/day of virginiamycin (VM) or 300 mg/day of virginiamycin plus 200 g/day of sodium bicarbonate (VM + NaHCO3). All cows were fed 1 kg/day of a pelleted mineral supplement containing the additives. The cows were grazed as a single herd on perennial ryegrass–subterranean clover pasture with pasture silage available during periods of pasture shortage. Rumen fluid was analysed for pH and volatile fatty acids, blood for plasma glucose, beta-hydroxy-butyrate, urea and D- and L-lactic acid, faeces for dry matter and pH, and both urine and milk for urea and sodium. The incidence of grain bloat in all treatments was low. There was no main effect of dietary additive treatment on grain intake, but at the highest grain level, cows offered VM or VM + NaHCO3 ate more grain than those offered no dietary additive. There were no significant differences between the dietary additive treatments in milk production, milk composition, cell count, liveweight and condition score. Mean daily covariance-corrected yields of milk and protein (kg), and milk protein content (g/kg) respectively, were significantly (P&lt;0.01) greater for cows fed 11 (28.0, 0.86, 30.6) and 14 kg/day (28.7, 0.88, 31.0) of concentrate compared with those fed 8 kg/day (26.4, 0.78, 29.7). Mean milk fat content (g/kg) was significantly (P&lt;0.01) lower in milk from cows fed 14 kg/day (32.0) of concentrate compared with those fed 8 (35.9) or 11 (34.7) kg/day. There were no significant differences between concentrate feeding levels in milk fat yield or milk somatic cell count. Covariance-corrected liveweight and condition score were significantly (P&lt;0.01) higher for cows fed 14 kg/day of concentrate compared with cows fed at the lower concentrate levels. There were no significant interactions between concentrate level and dietary additive for all milk production parameters. No significant differences were recorded between the different levels of concentrate in the concentration of total rumen volatile fatty acids, or in blood plasma concentrations of glucose and L-lactate. The rumen molar proportions of acetate and butyrate were significantly (P&lt;0.01) lower, and propionate and valerate significantly (P&lt;0.01) higher at the higher levels of concentrate offered. The molar ratio of acetate plus butyrate to propionate was significantly (P&lt;0.01) higher in cows fed 8 kg/day of concentrate compared with cows fed 11 and 14 kg/day. It was concluded that the inclusion of virginiamycin, or virginiamycin together with sodium bicarbonate, in high grain rations cannot be recommended for improving milk production in grazing dairy cows already adapted to high levels of barley and lupin grain.

Comparison of alfalfa and fenugreek (Trigonella foenum-graecum) silages supplemented with barley grain on performance of growing steers

To compare nutritive value of alfalfa and fenugreek silages for weaned back-grounding feedlot steers, isonitrogenous diets of alfalfa or fenugreek silage, supplemented with three levels of steam-rolled barley (0, 15 and 30% DM) were fed ad libitum to 60 steers (initial weight of 237 ± 18 kg). The study was conducted in individual pens for 105 d using a 2 × 3 factorial experiment. Fenugreek was cut 17 wk after seeding while the alfalfa was cut at mid-bloom. Both fenugreek and alfalfa silages were prepared in plastic tube silos after wilting to 38 and 35% DM, respectively. After ensiling for 40 d, silage tubes were opened and a feeding trial was conducted. Alfalfa and fenugreek silage contained similar levels of CP (18.0 and 17.2%, respectively) while fenugreek silage contained a lower level of NDF (38.2%) than alfalfa silage (40.4%). Dry matter intake (DMI) and average daily gain (ADG) of steers increased (P &lt; 0.001) and feed efficiency (FE) improved linearly (P &lt; 0.001) with increasing grain level in the diet. Dry matter intake (6.4 vs. 6.2 kg d−1), ADG (0.82 vs. 0.84 kg d−1), FE (8.1 vs. 7.8), total rumen volatile fatty acids (103.4 vs. 105.3 mM), rumen fluid pH (6.9 vs. 6.9) and rumen ammonia concentration (9.6 vs. 10.4 mg dL−1) in steers were similar for both alfalfa- and fenugreek-silage-based diets, respectively. Although in vitro rate of gas production was different at 12.6 and 17.4% h−1 for alfalfa and fenugreek diets, respectively, potential gas production at the end of 72 h of fermentation was similar (21.6 vs. 22.3 mL 100 mg−1 DM). The presence of steroidal saponins in fenugreek plants did not affect steer performance or hormonal status when fed as silage. Results from this study indicate that the nutritive value of fenugreek silage is comparable to that of mid-bloom alfalfa silage, and that fenugreek, a high-DM yielding annual legume, has potential to be a valuable forage in feedlot diets. Key words: Alfalfa silage, fenugreek silage, annual legume, feedlot, steer, barley

Influence of dietary rumen-degradable protein on bacterial growth in the rumen of sheep receiving different energy sources

An experiment with ruminally cannulated sheep was undertaken to determine how the dietary energy source affected the ability of rumen fermentation to respond to pre-formed amino acids compared to non-protein nitrogen in the diet. Four sheep received diets of grass hay (H) or molassed sugar beet pulp (BP) supplemented with 9.3 g N kg −1 DM added either as urea (U) or casein (C) in a 4 × 4 latin square with a factorial design. Measurements of rumen fermentation, microbial numbers and purine excretion were made in the third week of each 21-day period. Rumen total volatile fatty acids concentrations were higher with the BP diets (130 vs. 91 mM; P < 0.01), and the molar proportion of propionate was lower and that of butyrate was higher with BP, but the nitrogen source had no significant effect on volatile fatty acids. Rumen ammonia concentrations were lower with the BPU diet than with HU, and were decreased when casein replaced urea in both diets (11.1, 19.4, 5.0 and 10.2 mM for BPU, HU, BPC and HC respectively; P < 0.01). The source of nitrogen had no influence on microbial numbers or yield in the hay diets, but total viable bacteria more than doubled in response to pre-formed amino acids with BP (16.9 vs. 7.4 × 10 8 ml −1; P < 0.01). Microbial protein flow, calculated from urinary purine excretion, also increased in response to casein but only with BP (13.5 vs. 7.4 g N per day). The rate of loss of diets from nylon bags was much more rapid ( P < 0.01) with BP than with hay, and was unaffected by dietary nitrogen source ( P > 0.05). A microbial response to rumen-degradable protein therefore occurred only with the more rapidly degraded BP diet, consistent with the idea that rumen microbial growth responds to pre-formed amino acids only when the energy source is fermented rapidly.