Blood urea-N Research Articles

Productivity and nitrogen metabolism of lactating cows fed pistachio hull with soybean meal partially replaced by slow-release urea.

Pistachio hull (PH), a rich source of tannin, may interact with nitrogen (N) and affect N metabolism in dairy cows. This investigation aimed to assess the effects of feeding PH and two N sources (soybean meal: SBM or slow-release urea: SRU) on milk production, digestibility, and N metabolism in lactating dairy cows. The study utilized a 4 × 4 Latin square design with 12 Holstein dairy cows (body weight = 611 ± 39kg; 84 ± 14 days in milk; 45.6 ± 5.3kg/d milk), with treatments arranged in a 2 × 2 factorial configuration. The main factors were (1) the tannin source [without or with dried PH included at 76.5g/kg of diet DM] and (2) two N sources [SBM vs. SRU]. Crude protein and total phenolic and tannin contents were greater, but NDF was lower in PH than in sugar beet pulp. Feeding diets containing 7.65% PH resulted in reductions in milk yield, milk urea N, and milk efficiency but milk fat and protein concentration increased. Milk yield was similar between SBM and SRU. Feeding PH in replacement to sugar beet pulp did not interact with N sources, except for feed intake, as the PH + SRU diet tended to decrease feed intake (P = 0.09). Feeding PH was also associated with decreased dry matter, crude protein, and NDF digestibility. Dry matter digestibility decreased when a portion of SBM was replaced by SRU. Feeding PH in replacement to sugar beet pulp lowered ruminal ammonia-N concentration and increased acetate-to-propionate proportion. Feeding PH vs. sugar beet pulp had no effect on N intake and N excretion in urine and milk, but it increased the amount of N excretion in feces and decreased apparent N efficiency (milk N/N intake). Alanine aminotransferase was lower in cows fed SRU only in PH- but not sugar beet pulp-containing diets. Blood creatinine was lower when SRU was included in the PH-containing diet, but the opposite was observed in diets containing sugar beet pulp. Feeding PH instead of sugar beet pulp did not affect blood urea-N but resulted in lower glucose and aspartate aminotransferase concentrations. Overall, cows fed PH in replacement to sugar beet pulp were less efficient in converting feed nutrients into milk production, likely because of its negative effect on nutrient digestion. Partial replacement of SBM with SRU had no influence on lactation productivity and urea-N concentration in milk and blood. This may imply the suitability of SRU in providing a sustained supply of N in the rumen, likely qualifying it as a viable source of N to replace a portion of SBM in dairy diets.

Effects of sodium chloride intake on urea-N recycling and renal urea-N kinetics in lactating Holstein cows

The effects of high (2.5% of DM) versus normal dietary sodium chloride (NaCl) intake on renal urea-N kinetics and urea-N metabolism were investigated in 9 rumen-cannulated and multi-catheterized lactating dairy cows in a crossover design with 21-d periods. It was hypothesized that urinary urea-N excretion would be greater, and blood urea-N concentration lower in response to greater diuresis induced by high NaCl intake. Also, urea-N transport across ruminal and portal drained viscera (PDV) tissues was hypothesized to be affected by dietary sodium intake. A second experiment was conducted using 8 lactating cows in a crossover design with 14-d periods to test high NaCl (2.5% of DM) versus high KCl (3.2% of DM) intake on milk yield and milk urea-N concentrations. Experiment 1 showed that despite greater diuresis there was no effect of high NaCl intake on urinary urea-N excretion or blood urea-N concentration. The high NaCl intake did not affect rumen ammonia concentrations, total rumen VFA concentrations, ruminal venous - arterial concentration differences for ammonia, or ammonia absorption indicating that high NaCl did not adversely affect ruminal fermentation and microbial protein synthesis. High NaCl intake did not affect the total amount of urea-N transport from blood to gut, but ruminal venous - arterial concentration differences for urea-N were lower with high NaCl and ruminal extraction of arterial urea-N was numerically smaller, indicating that the ruminal epithelial urea-N transport was lower with high NaCl. Energy corrected milk yield was greater with high NaCl (3.2 ± 1.5 kg/d); however, milk urea-N concentrations were not affected by treatment. In experiment 2, ECM was greater with NaCl (1.4 ± 0.31 kg/d) compared with KCl (30.2 and 28.8 ± 0.91 kg ECM / d, respectively). Milk urea-N concentration was lower with KCl, suggesting a urea-N lowering effect in milk not evident with high NaCl intake. In conclusion, the present data show that dietary Na intake of 12-13 g/kg DM was followed by greater diuresis but did not impact urea-N excretion or blood urea-N concentration. High NaCl intake did not affect the total amount of urea-N transfer across PDV tissues. Energy corrected milk yield was greater with high NaCl compared with both control and feeding KCl, however, with KCl milk urea-N decreased.

Effects of quebracho–chestnut tannin extract supplementation on production performance, nitrogen partitioning, and rumen fermentation patterns in early-lactating Holstein cows

Tannins have been extensively studied to decrease nitrogen excretion, however, the effects of tannins on animal production were inconsistent. The objective was to evaluate the effects of a mixture of quebracho-chestnut tannin extract (QCTE) supplementation on the production performance, nutrient digestibility, rumen fermentation patterns, and N partitioning in dairy cows. Sixty multiparous Holstein cows (mean ± standard deviation; average 717 ± 51 kg of body weight, 2.5 ± 0.2 of parity, 47 ± 1.9 kg/d of milk production, 78 ± 3.2 d of days in milk were randomly divided into four groups. Cows in different groups were provided QCTE at doses of 0, 10, 20, and 30 g/d per cow for 56 d. Although QCTE supplementation did not affect dry matter intake (DMI) and total-tract apparent digestibility of nutrients, milk yield and milk protein yield increased linearly (P = 0.01), and a trend for a linear (P = 0.07) increase in milk/DMI were observed with increasing QCTE supplementation. Increasing QCTE supplementation decreased the milk urea-N concentration and somatic cell count linearly (P < 0.05), tended to linearly (P < 0.1) decrease the concentration of blood urea-N and ruminal ammonia nitrogen, linearly (P < 0.05) increased levels of total antioxidant capacity and superoxide dismutase, and the molar proportions of ruminal propionate. Additionally, total N excretion was not affected by QCTE treatments, but QCTE supplementation linearly (P = 0.04) increased N utilization efficiency and tended to linearly (P = 0.1) decrease urea-N excretion in the urine. In conclusion, feeding QCTE at a dose of 30 g/d per head to cows in early lactation could increase antioxidant enzyme activities, improve production performance, and decrease environmentally labile urinary N excretion under the conditions of the study.

Effects of feeding different dietary rates of mixed fodder beet tops-wheat straw silage on the performance of Holstein lactating cows.

Rations containing different rates of the mixed fodder beet tops-wheat straw silage (BS), instead of corn silage (CS), were given to 30 mid-lactation Holstein cows (all in parity 2) to measure the effects on feed consumption, milk production efficiency, milk chemistry, urinary purine derivatives (PD), blood chemistry, antioxidant levels, and in vitro methane (CH4) emission. The BS was prepared by mixing the fodder beet tops with wheat straw at a ratio of 9:1 based on fresh weight. The experimental design was completely randomized (one 28-d period with 21-d adaptation) using 30 cows (10 animals/treatment) and 3 treatments. The treatments were 1) a diet containing CS only (25g/100g DM) (CSD), 2) a diet containing 50% CS (12.5g/100g DM) and 50% BS (12.5g/100g DM) (CBSD), and 3) diet containing BS only (25g/100g DM) (BSD). Each animal (as an experimental unit) was housed individually in the tie stall and had ad libitum access to its diet. Dietary replacing 50% of CS with BS showed no significant differences in milk production, fat-corrected milk, fat and protein yields, feed efficiency, and apparent digestibility, however, these variables were less (P < 0.05) in the cows fed with BSD. Cows fed on BSD had less intakes of DM, organic matter, crude protein, and neutral detergent fiber but greater oxalic acid intake and blood urea-N, as compared to the other cows. Milk percentages of fat, protein, lactose, urea N, blood serum glucose, triglyceride, cholesterol, total protein, albumin, globulin, Ca, and P, as well as in vitro ruminal pH, were not affected by the diets. Saturated fatty acids concentration was less and monounsaturated FA and polyunsaturated FA (PUFA) was greater in the milk of cows receiving CBSD, compared to the other groups. The inclusion of both BS rates in the diet decreased the in vitro gas production, protozoa number, and CH4 emission in comparison to the control. Cows fed BSD had decreased levels of urinary allantoin, PD excreted or absorbed, and estimated microbial-N synthesis than the control and CBSD-fed groups. The milk and blood total antioxidant capacity (TAC) of the animals fed CBSD was the maximum among the cows. Overall, under the current experimental conditions, replacing 50% of dietary CS with BS did not affect milk production, but increased milk PUFA, as well as blood and milk TAC, and decreased in vitro CH4 emission, so it's feeding to lactating Holstein cows is recommended.

Effects of corn grain processing method in starter ration and weaning strategy on performance, nutrient digestion, rumen fermentation, and blood metabolites of Holstein calves

This research explored how corn processing methods and weaning protocols interact and impact calf performance, digestibility, ruminal fermentation, and blood metabolites. Forty-eight 3-day-old Holstein calves (24 females and 24 males; body weight = 38.2 ± 1.56 kg) were allocated to one of the four treatment groups using a 2 × 2 factorial design. The physical form of corn grain [steam-flaked corn (SFC) or ground corn (GC)] and weaning protocol [abrupt weaning (AW) or gradual weaning (GW)] were the experimental factors and resulted in the following treatments: 1) a starter diet containing SFC + AW protocol (SFC/AW), 2) a starter diet containing SFC + GW protocol (SFC/GW), 3) a starter diet containing GC + AW protocol (GC/AW), and 4) a starter diet containing GC + GW protocol (GC/GW). The starter feeds had similar feed ingredients (50.4% corn grain, 35.1% soybean meal, plus 5% chopped wheat straw) and were different only in the physical form of corn grain (SFC vs. GC). In the AW protocol, calves were given 4 L of milk/d from days 3 to 15, then increased to 7 L/d from days 16 to 67. Weaning occurred abruptly from days 68 to 69 by decreasing milk to 3.5 L/day. In the GW protocol, calves received 4 L of milk/day from days 3 to 15, followed by 7 L/day from days 16 to 59. Weaning occurred gradually from days 60 to 69, with this reduction schedule: 6 L/d from days 60–61, 5 L/d from days 62–63, 4 L/d from days 64–65, 3 L/d from days 66–67, 2 L/d on day 68, and 1 L/d on day 69. Total starter intake (d 1 to 90) remained unaffected by the corn grain processing method, but weaning strategy and corn processing method interacted for starter feed intake, as the greatest intake was observed in calves assigned in SFC/GW treatment. Feeding a starter diet containing SFC rather than GC increased DM and NDF digestion. Calves that were fed an SFC-based starter diet grew faster than calves fed a GC-based starter diet. The average daily gain (from d 1 and 90) was greater in calves assigned to GW vs. AW protocol. Calves fed an SFC-based starter feed and assigned to AW protocol converted nutrients toward growth more efficiently throughout the experiment (d 1 to 90). Feeding a GC- vs. SFC-based starter feed resulted in greater rumen ammonia-N concentration. Ruminal pH on day 80 was greater in calves weaned gradually compared to those weaned abruptly. Calves fed GC- vs. SFC-based starter diet had higher blood urea-N and β-hydroxybutyrate concentrations on day 60. Overall, an SFC- vs. GC-based starter feed (containing 5% chopped wheat straw) promoted faster calf growth and improved nutrient utilization. Feeding an SFC-based starter diet in combination with GW protocol resulted in the greatest starter feed intake.

Effects of chromium propionate supplementation on lactation performance, nutrient digestibility, rumen fermentation patterns, and antioxidant status in Holstein cows under heat stress

Chromium propionate (CrP) supplementation has the potential effects on mitigating metabolic stress on dairy cows, however, the effect of increased CrP supply on alleviating heat stress of mid-lactation cows is rarely evaluated. This study was conducted to evaluate the effect of CrP supplementation on lactation performance, nutrient digestibility, rumen fermentation patterns, and antioxidant status in dairy cows under heat stress. Sixty-four Holstein dairy cows in mid-lactation with similar parity (2.1 ± 0.2), current milk production (40 ± 1.4 kg/d), and days in milk (143 ± 7.8 d) were randomly allocated to one of four treatments with a completely randomized design. After a 7-day adaptation period, cows were fed CrP at doses of 0, 4, 8, and 12 mg/d of Cr per head for 49 d. The average temperature humidity index (THI) was 77 during the experimental period. The average respiration rate and rectal temperature decreased quadratically (P < 0.01) with increasing CrP supplementation. Dry matter intake (DMI), milk yield, and milk lactose yield increased quadratically (P < 0.05) with increasing CrP supplementation, whereas 4% fat-corrected milk was not affected by treatments, and feed efficiency tended to decrease quadratically (P = 0.07). The percentage of milk protein and lactose increased linearly (P = 0.05) with increasing CrP supplementation, whereas milk urea-N concentration and somatic cell count decreased quadratically (P < 0.01). Although total-tract apparent digestibility of dry matter, organic matter, crude protein, and ether extract was not affected by CrP supplementation, neutral detergent fiber digestibility increased quadratically (P = 0.01) with increasing CrP supplementation. The concentrations of milk Cr and urinary Cr were not affected by CrP supplementation. Ruminal pH, the concentration of total VFA and ammonia-N, and the molar proportion of propionate and butyrate were not affected by treatments, whereas the molar proportion of acetate increased quadratically (P < 0.01) with increasing CrP supplementation. The blood urea-N concentration decreased quadratically (P < 0.01) and the concentration of glutathione peroxidase and superoxide dismutase increased quadratically (P < 0.01) with increasing CrP supplementation, while the ratio of glucose to insulin and the concentration of glucose and malonaldehyde did not differ among treatments. In conclusion, CrP supplementation could increase milk yield in mid-lactation cows under heat stress by increasing DMI, reducing respiration rate and rectal temperature, and improving antioxidant status. The recommended dose of CrP is 4–8 mg/d of Cr per cow in hot weather.

Digestibility Coefficients, Some Blood and Rumen Metabolites and Physiological Responses in Sudan Nubian Goats Subjected to Varying Levels of Feed and Water Restrictions

Three yearling uncastrated males of Sudan Nubian goatsranging in weight between 14 and 20 kg were used in a 3x3 latin squaredesign experiment with the objective of studying the effects of feed andwater restriction on dry matter intake (DMI), water intake, digestibility ofnutrients, rumen components, blood urea-N (BUN), rectal temperatureand respiration rate. The experiment consisted of three treatments:Adlibitum feed and water, feed restricted to 50% of adlibitum level withadlibitum water, water restricted to 50% of adlibitum level with adlibitumfeed. The results revealed no significant treatment effects on water intake,urine volume, rectal temperature and respiration rate. However, DMIdiffered significantly between treatments. The adlibitum provision ofwater resulted in insignificant higher water intake compared with theother two treatments. Rectal temperature was higher in water restrictedgoats than in feed restricted goats, whereas respiration rate decreasedinsignificantly with both feed and water restrictions. Feed and waterrestrictions had no effect on the digestibility coefficients of the variousnutrients. Water restricted goats showed, however, different trends exceptfor ether extract digestibility which tended to decrease. Treatment had nosignificant effect on the total digestible nutrients (TDN) values. The TDNtended to be higher with water restriction. There was no significanttreatment effect on rumen pH, ammonia-N (NH3 -N) and BUN. Feed andwater shortage did not significantly affect digestibility of the proximatecomponents but tended to slightly affect rumen metabolites, BUN,respiration rate and rectal temperature.

Effect of Rhodanese Enzyme Addition on Rumen Fermentation, Cyanide Concentration, and Feed Utilization in Beef Cattle Receiving Various Levels of Fresh Cassava Root

Fresh cassava root is not recommended for animal feeding due to high quantities of hydrocyanic acid (HCN), which produces symptoms of poisoning. The purpose of this study was to find out how a rhodanese enzyme addition affects rumen fermentation, HCN content, feed utilization, and blood metabolites in beef calves fed fresh cassava root. Four Thai native beef cattle with an initial body weight (BW) of 95 ± 10.0 kg (1–1.5 years old) were randomly allocated to receive fresh cassava root containing HCN at 0, 300, 450, and 600 ppm according to a 4 × 4 Latin square design. Rice straw was the basal diet. The rhodanese enzyme was combined with concentrated feeds at a concentration of 1 mg/104 ppm HCN. The fresh cassava root was cleaned to remove dirt and chopped into 3 to 5 mm sized pieces before being fed to the animals at their various levels. The total feed intake of beef cattle increased when fed with fresh cassava root (p &lt; 0.05). The digestibility of crude protein (CP) was different among various fresh cassava root levels (p &lt; 0.05). Ruminal ammonia-N levels were measured 4 hours after feeding, and the average concentration declined considerably in animals fed fresh cassava root at 300–600 ppm HCN (p &lt; 0.05). Cyanide concentration in the rumen was linearly increased by 270.6% (p &lt; 0.05) when it was supplemented with a high level of fresh cassava root. Blood urea-N concentration was altered and decreased when supplemented with fresh cassava root (p &lt; 0.01). The blood thiocyanate concentration was altered by the levels of fresh cassava root and rhodanese enzyme, which ranged from 4.1 to 27.9 mg/dL (p &lt; 0.01). Cattle given fresh cassava root showed no influence on total volatile fatty acid, acetic acid, or butyric acid concentrations in the rumen (p &gt; 0.05). However, the concentration of propionic acid increased slightly (p &lt; 0.05) 4 hours after feeding. Supplementing fresh cassava root up to 600 ppm HCN/day improved N absorption, retention, and the proportion of N retention to N intake (p &lt; 0.05). Therefore, increasing the inclusion of fresh cassava root with a rhodanese enzyme addition improves total feed intake, CP digestibility, nitrogen utilization, blood thiocyanate, and propionate concentrations, which may remove HCN without harming animal health.

331 Effects of Dried Distillers’ Grains Cube Supplementation Rate on Voluntary Intake and Digestibility of Bermudagrass Hay Fed to Growing Heifers

Abstract The objective of this study was to evaluate supplementation rates of dried distillers’ grains cubes (DDGS) on voluntary intake (DMI), rate and extent of digestibility, and blood parameters of growing Charolais-cross heifers (BW = 286 ± 28.9 kg) fed ad libitum bermudagrass (Cynodon dactylon) hay. For the 29-d study, heifers were randomly assigned to one of four supplementation treatments: 1) Control, no supplement (n = 6); 2) Low, supplemented 0.90 kg/d (n = 6); 3) Intermediate, supplemented 1.81 kg/d (n = 5); or 4) High, supplemented 3.62 kg/d (n = 6). Heifers were offered supplement each morning in individual stalls. From d 15 to 25, heifers were dosed twice daily with titanium dioxide in gelatin capsules (10 g/d), and fecal samples were collected via rectum at time of dosing from d 22 to 25 to estimate fecal output. Post-dosing, fecal sampling continued over 96-h from d 25 to 29 to determine passage rate (Kp) via titanium dioxide analysis. Blood was collected from each animal on d 26 via jugular venipuncture before supplementation, and 4 and 8-h post-supplementation for analysis of blood urea N (BUN), lactate, and glucose. Samples of feces, hay, and supplement were incubated in rumen-cannulated Holstein steers (n = 4; BW = 281 ± 29.5 kg) for 576-h to estimate digestibility with indigestible neutral detergent fiber as an internal marker. Data were analyzed by ANOVA using the mixed procedure of SAS (SAS Inst. Inc. Cary NC), with treatment least-squares means separated using orthogonal polynomial contrasts. Increasing DDGS linearly (P &amp;lt; 0.01) decreased forage DMI linearly, but linearly increased Kp, total diet DMI, and total diet digestibility. Linear increases (P ≤ 0.02) in glucose, lactate, and BUN were likewise observed with increasing DDGS. Increasing DDGS supplementation to growing calves consuming bermudagrass hay may increase productivity while reducing forage intake.

Effects of replacing steam-flaked corn with shredded sugar beet pulp on feed sorting, behavior, blood metabolites, and growth performance of dairy calves.

This experiment was conducted to investigate the effects of partial replacement of steam-flaked corn (SFC) with shredded sugar beet pulp (SBP) in the starter diet on selective intake (sorting), feeding and chewing behavior, blood biochemical parameters, and growth in newborn female Holstein dairy calves. A total of 48 calves (3 d old; 40.1 ± 0.84 kg body weight; mean ± SE) were randomly assigned to 1 of 2 feeding treatments containing 0 or 25% SBP (percentage of dry matter [DM]) in the starter diet. Calves were weaned on d 61 and remained in the study until d 81. Intake of starter feed and total intake of DM (milk DM + starter feed DM), crude protein, and neutral detergent fiber were increased (P < 0.05) by feeding SBP; however, intake of starch (P < 0.01) and total intake of ether extract (P = 0.03) were decreased with no apparent effect on total intake of ME. Average daily gain, feed efficiency, final weight, and skeletal growth also showed no significant changes. Circulating concentrations of glucose, total protein, and albumin were not affected by partial replacement of SBP with SFC; however, higher concentrations of blood urea-N (P = 0.01) and a lower albumin-to-globulin ratio (P = 0.03) were observed in SBP- vs. SFC-fed calves. Calves fed SBP sorted more for particles retained on the 4.75-mm sieve (P = 0.02) and against particles retained on the 0.6-mm sieve and bottom pan (P < 0.01). Intake of neutral detergent fibers and starch from particles retained on all sieve fractions was increased and decreased (P < 0.01), respectively, by replacing SFC with SBP. Replacement of SBP with SFC was associated with increased meal length and meal size and increased rumination frequency and length, but decreased intervals between rumination (P ≤ 0.01). Calves fed SBP spent more time eating, rumination, and standing and less time lying and non-nutritive oral behaviors (P < 0.01). In general, 25% replacement of SFC with SBP did not affect calf performance but increased time spent rumination and eating and decreased non-nutritive oral behaviors.

Production efficiency, milk yield, and milk composition and fatty acids profile of lactating goats feeding formaldehyde-treated canola meal in two levels of dietary crude protein

The effectiveness of formaldehyde treated canola meal (FTCM) in two levels of dietary crude protein (CP) were evaluated in an experiment. Eight multiparous lactating Raini goats (early lactation, 32 ± 2 kg BW) were used in a 4 × 4 Latin square design with four treatments. Experimental diets were: (1) diet with 14.5 % CP containing untreated canola meal (UCM) (CON), (2) diet with 14.5 % CP containing FTCM (0.8 g/100 g CP) (FT1), (3) diet with 14.5 % CP containing FTCM (1.2 g/100 g CP) (FT2), and (4) diet with 12.5 % CP containing FTCM (1.2 g/100 g CP) (LPFT2). Dry matter intake (DMI) of the goats was significantly increased by substitution of FTCM in the diet (P < 0.001). Feeding FT2 and LPFT2 diets significantly increased production of milk, fat-corrected milk (FCM), energy-corrected milk (ECM), total-solids-corrected milk (TSCM) (P < 0.001), and yields of fat, protein, lactose, total solids, and non-fat solids (P < 0.01). However, dietary treatments did not affect milk composition of the goats. Production efficiency for milk and FCM were highest (P < 0.001) in goats fed the LPFT2 diet. Moreover, the FT1 diet decreased C4:0, C6:0, C8:0, C10:0, C12:0, C15:0, C17:0, t-C18:3, and total short-chain and long-chain fatty acids (FA) of the milk (P ≤ 0.01), but C16:0 and total medium-chain FA were increased (P ≤ 0.01) as compared to CON and FT2. Although formaldehyde treating did not affect ruminal pH, the concentrations of ruminal ammonia-N (NH3-N), and blood urea-N (BUN) decreased by feeding FT2 and LPFT2 diets (P < 0.001). Also, LPFT2 diet increased concentration of total ruminal VFA (TVFA) and showed lower acetate/propionate ratio when fed to the goats (P < 0.05). In general, substitution of 1.2 % FTCM had improved feed intake and productive performance of lactating goats; it is therefore concluded that formaldehyde treating of canola meal can be used as an economical choice for increasing dietary bypass protein, by which the level of diet crude protein can be reduced.

Effects of feeding sodium metabisulfite-treated fruit and vegetable discards to Hanwoo heifers and cows.

ObjectiveTwo series of experiments were conducted to determine how the incremental levels of sodium metabisulfite (SMB)-treated fruit and vegetable discards (FVD) in diet of Hanwoo heifers and cows affect their performance and health.MethodsIn Exp. 1, 36 Hanwoo heifers were stratified by age (13.3±0.83 mo) and initial body weight (305±19.7 kg), and divided randomly to one of three diets containing 0%, 10%, or 20% SMB-treated FVD (as-fed basis). The experiment lasted 110 d, including 20 d of adaptation. In Exp. 2, 24 multiparous Hanwoo cows were divided into three groups based on age (48.2±2.81 mo) and initial body condition score (2.64±0.33). Cows in each block were assigned randomly to one of three diets containing 0%, 11%, or 22% SMB-treated FVD (as-fed basis). The experiment lasted 80 d, including a 20-d adaptation period. In both experiments, SMB-treated FVD was used as a replacement for wet brewers grain in total mixed ration (TMR).ResultsGrowing heifers exhibited no differences in their daily feed intake (6.58±0.61 kg/d dry matter [DM]), average daily gain (0.60±0.07 kg/d), and body condition score when they consumed the incremental levels of SMB-treated FVD. Although most blood metabolites were unaffected by treatments, blood urea-N and β-hydroxybutyrate levels decreased linearly as the SMB-treated FVD level increased in TMR. Similar to Exp. 1, minor differences were found in daily feed intake (8.27±0.72 kg DM/d) and body condition score of Hanwoo cows. Most blood metabolites remained unaffected by treatments, but blood urea-N decreased as the SMB-treated FVD level in TMR increased.ConclusionOur findings suggest that SMB-treated FVD could be safely incorporated into the diet of Hanwoo heifers and cows, potentially improving N-use efficiency in the body while not impairing performance or health.

Dry matter intake, digestibility, nitrogen utilization and fermentation characteristics of sheep fed Atriplex hay-based diet supplemented with discarded dates as a replacement for barley grain.

This experiment aimed to investigate the effects of substituting barley grain with discarded dates on intake and digestibility, nitrogen (N) utilization and fermentation characteristics of sheep fed Atriplex hay-based diets. Four Barki sheep (50.9±2.93kg of body weight (BW)) fitted with rumen cannula were used in a 4×4 Latin Square design with 23-day periods. Four isonitrogenous (~140g crude protein (CP)/kg of dry matter (DM)) experimental diets were formulated with Atriplex hay, and dietary sugar content was increased by replacing barley grain with discarded dates (the proportions of discarded dates in the diet were 0, 93, 187 and 280g/kg DM). Nutrient intakes were not influenced by diet. Organic matter, CP and neutral detergent fibre digestibility increased (p<0.05) linearly and DM digestibility tended to increase with increased dates inclusion. Ruminal pH and molar proportion of butyrate increased (p<0.05) linearly with increasing levels of dates inclusion, whereas ruminal ammonia-N decreased (p<0.05) linearly. Total volatile fatty acid concentration was unaffected. Microbial protein synthesis (MCP) increased linearly and efficiency of microbial protein synthesis tended to increase as discarded dates increased. Total N intake was not affected by diets whereas, urinary N, urea-N and total N execrations linearly decreased (p<0.05) with higher amounts of dates in the diets. Blood urea-N tended to decrease with increasing levels of dates. It could be concluded that replacing 100% barley grain with discarded dates as a source of soluble carbohydrates can enhance the utilization of N in Atriplex hay-based diet and consequently improve digestibility and MCP.

Effect of nano-ZnO, compared to ZnO and Zn-methionine, on performance, nutrient status, rumen fermentation, blood enzymes, ferric reducing antioxidant power and immunoglobulin G in sheep

This study was conducted to assess the effect of nano-ZnO, compared to ZnO and Zn-methionine, on dry matter (DM) intake (DMI), performance, nutrient status, digestibility, rumen fermentation, microbial nitrogen (N) synthesis (MNS), blood enzymes, ferric reducing antioxidant power (FRAP) and immunoglobulin G (IgG) in sheep. Thirty-six healthy male Shal sheep were divided into four experimental groups (n = 9) in a completely randomized design, and assessed for 40 days. The control animals received the basal diet without Zn supplementation, containing a native Zn content of 22.6 mg/kg DM. Other sheep were fed with the diets containing 28 mg supplementary Zn/kg DM in the form of ZnO, Zn-methionine or nano-ZnO. The DMI of sheep receiving Zn-methionine was higher (P = 0.035) than the control group, but was similar among the Zn-supplemented groups. Although supplementation of the basal diet with Zn increased (P < 0.05) the digestibility, rumen total volatile fatty acids (VFA), average daily gain and feed efficiency, the chemical forms of Zn did not affect these variables. The intake, daily absorption, retention and blood concentration of Zn were not affected by using nano-ZnO instead of ZnO and Zn-methionine. The animals receiving Zn-methionine had higher (P = 0.019) rumen fluid Zn than the ZnO fed sheep. Compared to the control diet, the Zn supplementations increased retained N (P = 0.037) and decreased rumen ammonia-N (P = 0.046). Using nano-ZnO instead of ZnO and Zn-methionine had no effect on rumen ammonia-N, retained N and MNS. The blood urea-N (BUN) concentration was lower (P = 0.027) for the Zn-methionine and nano-ZnO fed animals versus the control and ZnO groups. The nano-ZnO and Zn-methionine fed sheep had higher (P < 0.05) rumen and blood FRAP and Zn absorbability than the ZnO group. The blood IgG concentration was higher (P = 0.028) for the Zn-methionine and nano-ZnO fed animals versus the control sheep, and nano-ZnO group versus the ZnO fed animals. There were no differences among sheep in terms of the ruminal pH, individual VFA proportions and protozoa counts, Cu status and blood alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase. Overall, using nano-ZnO in the diet of sheep had advantages over ZnO in terms of increasing the Zn absorbability, rumen and blood FRAP and blood IgG, and decreasing BUN. However, there were no differences between the animals consuming nano-ZnO or Zn-methionine.

A blend of essential oils improved feed efficiency and affected ruminal and systemic variables of dairy cows.

This experiment evaluated the effect of a blend of essential oils (BEO) on intake, lactation performance, diet digestibility, ruminal fermentation profile, eating behavior, body thermoregulation, blood acid–base balance, and milk fatty acid profile of lactating cows. Twenty-eight Holstein cows were individually fed a standard diet for 14 d and treatments control or BEO (a microencapsulated blend of pepper extract containing capsaicin and pure forms of carvacrol, cinnamaldehyde, and eugenol; 150 mg/kg of diet dry matter) for 56 d. Significance was declared at P ≤ 0.05 and trends at 0.05 < P ≤ 0.10. Dry matter intake (DMI) was reduced (19.5 vs. 20.1 kg/d) and milk yield was increased (30.1 vs. 30.8 kg/d) by BEO, inducing improved milk to DMI ratio (1.53 vs. 1.62). Milk fat concentration tended to be increased by BEO, but total solids yield did not differ. There was a trend for increased total tract non-neutral detergent fiber organic matter digestibility with BEO. The molar proportion of acetate in ruminal fluid was reduced (51.4 vs. 57.8%) and that of propionate was increased (26.1 vs. 31.3%) by BEO. Ruminal microbial yield and total protozoa count in ruminal fluid did not differ. Cows fed BEO ingested a greater proportion of the daily intake in the morning (30.6 vs. 36.6%) and tended to ingest a lower proportion at night, tended to have longer meals, and had fewer meals per day (11.9 vs. 13.7) and larger meal size (1.5 vs. 1.7 kg of dry matter per meal). Blood urea-N and glucose concentrations did not differ. The BEO increased jugular blood oxygenation. The sweating rate on a hot and dry day was increased (160 vs. 221 g/m2/h) by BEO. The mean rectal and skin temperatures and respiration rate did not differ, but the proportion of rectal temperature measurements ≥39.2 °C was reduced by BEO at 1400 h (17.8 vs. 28.5%) and 2000 h (23.2 vs. 34.8%). The BEO increased the secretion (g/d) of 18:2 trans-10, cis-12 and the concentration of 18:0 iso fatty acids in milk fat. When one sample of milk from BEO cows was offered with two samples of milk from control, 59% of regular consumers of milk (n = 63) identified the odd sample correctly. The gain in feed efficiency induced by BEO was associated with reduced acetate-to-propionate ratio in ruminal fluid, altered eating behavior, lower frequency of high rectal temperature, and increased blood oxygenation. Essential oils had positive effects on ruminal fermentation and systemic variables of dairy cows.

An evaluation of Molly cow model predictions of ruminal metabolism and nutrient digestion for dairy and beef diets

Model evaluation, as a critical process of model advancement, is necessary to identify adequacy and consistency of model predictions. The objectives of this study were (1) to evaluate the accuracy of Molly cow model predictions of ruminal metabolism and nutrient digestion when simulating dairy and beef cattle diets; and (2) to identify deficiencies in representations of the biology that could be used to direct further model improvements. A total of 229 studies (n = 938 treatments) including dairy and beef cattle data, published from 1972 through 2016, were collected from the literature. Root mean squared errors (RMSE) and concordance correlation coefficients (CCC) were calculated to assess model accuracy and precision. Ruminal pH was very poorly represented in the model with a RMSE of 4.6% and a CCC of 0.0. Although volatile fatty acid concentrations had negligible mean (2.5% of mean squared error) and slope (6.8% of mean squared error) bias, the CCC was 0.28, implying that further modifications with respect to volatile fatty acid production and absorption are required to improve model precision. The RMSE was greater than 50% for ruminal ammonia and blood urea-N concentrations with high proportions of error as slope bias, indicating that mechanisms driving ruminal urea N recycling are not properly simulated in the model. Only slight mean and slope bias were exhibited for ruminal outflow of neutral detergent fiber, starch, lipid, total N, and nonammonia N, and for fecal output of protein, neutral detergent fiber, lipid, and starch, indicating the mechanisms encoded in the model relative to ruminal and total-tract nutrient digestion are properly represented. All variables related to ruminal metabolism and nutrient digestion were more precisely predicted for dairy cattle than for beef cattle. This difference in precision was mostly related to the model's inability to simulate low forage diets included in the beef studies. Overall, ruminal pH was poorly simulated and contributed to problems in ruminal nutrient degradation and volatile fatty acid production predictions. Residual analyses suggested ruminal ammonia concentrations need to be considered in the ruminal pH equation, and therefore the inaccuracies in predicting ruminal urea N recycling must also be addressed. These modifications to model structure will likely improve model performance across a wider array of dietary inputs and cattle type.

Nitrogen balance of bullocks fed Cratylia argentea and Brachiaria arrecta Hay

Four experimental diets or treatments formed with incremental proportions of the foliage of tropical shrub legume Cratylia argentea and decremental proportions of Tanner grass (Brachiaria arrecta) hay: T1, 0:100; T2, 15:85; T3, 30:70; and T4, 45:55 were evaluated using four Holstein-Zebu bullocks (214.5 9.3 kg) conned in individual pens, under a balanced 4 x 4 latin square design. The crude protein (CP, %) content of C. argentea was 19.3 ± 6%, and in the grass was 6.2 ± 3%. The intake of DM increased as the C. argentea level in the diet increased. Blood urea-N (BUN) showed a linear increase from T1 to T4, observing its highest concentration at feeding time and six-hours after in T4: 12.00 and 14.75 mg dL-1, respectively. Purine derivatives (uric acid and allantoin) were not affected by treatments (p &gt; 0.05). The increase of the legume in the diet improved the DM intake and digestibility, and led to N-balance from negative in T1 and T2, to positive in T3 and T4. The legume proportion in a basal diet of the grass B. arrecta must be 30% at least.

Stockpiled "Tifton 85" bermudagrass for cow-calf production as influenced by nitrogen fertilization.

A 2-yr study was conducted to determine the effects of rate of N fertilization on productivity and nutritive value of stockpiled "Tifton 85" bermudagrass for lactating-cow and calf performance. On 31 October 2012 (year 1) and 11 November 2013 (year 2), 16 Angus × Simmental cows (mean initial BW for both years, 647 ± 23 kg) and their calves (mean age for both years, 16 ± 3 d) were assigned randomly to 0.76-ha paddocks (2 cow-calf pairs/paddock) of stockpiled "Tifton 85" bermudagrass pasture that had been cut to a 10-cm stubble height in early August and fertilized with either 56 (56N), 112 (112N), or 168 (168N) kg N/ha (2 paddocks/treatment), or to replicate 0.41-ha paddocks (2 cow-calf pairs/paddock) of dormant pasture with free-choice access to August-cut "Tifton 85" bermudagrass hay plus 2.7 kg whole cottonseed daily (HAY). Cows were allowed access to strips of ungrazed forage by moving polytape every 3 to 4 d to maintain a DM harvest efficiency of approximately 75%. In year 1, forage mass (6,113 kg DM/ha), IVDMD (60.9%), and grazing d/ha (314) were not different (P > 0.05) among the stockpile treatments over a 116-d grazing period; mean forage IVDMD (60.1%) and CP (12.7%) in the stockpiled treatments were greater (P < 0.05) than the HAY treatment. Stockpiled forage CP concentration was greater (P < 0.05) for the 168N than 56N and 112N treatments and was greater (P < 0.05) for the 56N than 112N treatment. In year 2, mean forage CP concentration was greater (P < 0.05) for the 168N (14.5%) than 56N (11.3%), 112N (12.0%), and HAY (9.0%) treatments; mean stockpiled forage IVDMD (59.5%) was greater (P < 0.05) than the HAY treatment (46.3%); and mean forage mass for the 168N treatment (5,017 kg DM/ha) was 378 kg and 298 kg DM/ha greater (P < 0.05) than the 112N and 56N treatments, respectively. Mean cow BW (611 ± 147 kg), body condition scores (5.5 ± 0.6), and milk production (9.0 ± 6.0 kg/d) were not different (P > 0.05) among treatments. Mean blood urea-N (BUN) concentrations (11.2 mg/mL) were not different among treatments, but mean BUN across treatments for the last sampling date was greater (P < 0.05) than the first and second sampling dates. Mean 205-d adjusted weaning weight (249 kg ± SD) was not different among treatments. Economic evaluation revealed that input costs/cow were 66%, 61%, and 56% greater for HAY than 56N, 112N, and 168N, respectively. Stockpiled forages were of sufficient nutritive quality to support lactation without supplementation.

Effects of replacing dietary maize grains with increasing levels of sugar beet pulp on rumen fermentation constituents and performance of growing buffalo calves

This study was conducted to evaluate the effects of replacing cracked maize with increasing levels of sugar beet pulp (SBP) on nutrients digestibility, blood biochemical and rumen fermentation constituents and animal performance of growing Egyptian buffalo calves. Forty male Egyptian buffalo calves (237.2±24.46kg of initial body weight, IBW) were allocated into a completely randomized design and stratified to one of four experimental diets. The basal diet was isonitrogenous (40:60 forage: concentrate) and was formulated to contain 60% of dietary DM cracked maize replaced by ascending levels of SBP (0, 333, 667, and 1000g/kg respectively). The study lasted for a period of 143days from which 21days for adaptation while the remaining 122days were used for data collection. Increasing the level of SBP resulted in a quadratic increase (P=0.017) in the average daily gain (ADG) with a linear tendency of increase (P=0.064) in dietary dry matter intake. A quadratic decrease of feed conversion ratio (FCR, P=0.005) was observed with the ascending levels of SBP. In addition, the daily intake of organic matter, neutral detergent fiber assayed with heat stable α-amylase and corrected for ash (aNDFom), acid detergent fiber corrected for ash (ADFom) were quadratically (P<0.01) improved upon increasing the dietary SBP level while the daily intake and digestibility of ether extract were declined linearly (P<0.01). Replacing SBP for maize resulted in linear increase (P<0.01) in OM, aNDFom, cellulose and hemicellulose digestibility coefficients. Ruminal pH, total short chain fatty acids, proportions of acetate (C2) and butyrate were increased linearly (P<0.05). In contrast, the proportions of propionate (C3) and isobutyrate were decreased linearly (P<0.05) upon increasing the levels of SBP. In addition, the C2:C3 ratio and total protozoa were linearly (P<0.01) increased while the ruminal NH3-N concentration was quadratically (P=0.046) increased as SBP replaced maize in the diet. Furthermore, upon increasing the dietary SBP levels, the blood urea-N, cortisol and thyroxin (T4) concentrations were quadratically elevated (P<0.01). Conversely, linear decreases in creatinine, (P=0.027) and cholesterol (P=0.001) concentrations were found. In addition, blood insulin like growth factor-1 (IGF-1) concentration increased linearly (P=0.006) as SBP level increased. Feeding cost based on BW gain was linearly reduced (P=0.043) by 25%, causing the overall profits ($/head/d) to be quadratically (P<0.01) increased. Overall, the obtained results indicate that replacing maize grains with up to 667g SBP/kg diet resulted in a highest profit by 21%, enhanced ruminal fermentation, nutrients digestibility and ADG and reduced FCR. Therefore, this study could be economically feasible for use in fattening diets of growing Egyptian buffalo calves without impairing animal performance or health.

Feeding value of whole raw soya beans as a protein supplement for beef cattle consuming low-quality forages.

Experiments (Exp) I and II were conducted to compare raw whole soya beans (WSB), roasted (rWSB) or other protein sources as supplements of low-quality forages fed ad libitum to beef cattle, upon DM intake (DMI), ruminal and blood parameters, and animal performance. Exp I: treatments for wheat straw fed to four ruminally cannulated steers were (i) Control-WS: no supplement; (ii) WSB-WS: whole soya beans; (iii) rWSB-WS: roasted WSB; and (iv) SBM-WS: soybean meal-wheat midds mixture; all fed at 1.4kgDM/day. Exp II: 12 steers grazed deferred grain sorghum (DS) receiving these treatments: (i) Control-DS: no supplement; (ii) WSB-DS: 1.26kg DM/day whole soya beans; and (iii) SFM-DS: 1.35kg DM/day of sunflower meal. In Exp I, WS DMI resulted 47, 52 and 41% greater for WSB-WS, rWSB-WS and SBM-WS, respectively, than Control-WS (p<.05). In Exp II, the DMI of DS was unaffected by supplementation; a substitution of DS by supplement was found for WSB-DS (p<.05); however, total diet and digestible DMI increased with supplementation (p<.05). Rumen pH in Exp I remained unaffected by supplementation, but N-NH3 as well as blood urea-N in Exp II increased (p<.05). In Exp II, average daily weight gains improved similarly with both supplements compared with Control-DS. Additionally, feed-to-gain ratio decreased (p<.05), being lower for WSB-DS (8.3) vs. SFM-DS (9.9). Roasting effects of WSB as a supplement for low-quality forages were not detected, and all protein sources increased total diet DMI and forage utilization. Only moderate cattle weight gains could be expected for unsupplemented DS.