Rumen Ammonia Research Articles

Evaluation of the use of arid-area rangelands by grazing sheep: Effect of season and supplementary feeding

Twenty-four one-year-old male Abu-duleik local sheep were used to evaluate the use of natural rangelands under arid conditions. Dry and wet seasons were considered, each with twelve different animals divided into two treatments. Animals grazed the natural plants with (GS) or without (G) concentrate supplement. Esophageal fistulae were established in another eight two-year-old male to study the botanical composition of forages sheep consumed. Another sixteen one-year-old male were maintained in metabolic cages to determine the marker fecal recovery to be used in calculating feed intake and digestibility. The results of the grazing experiment revealed that average daily gain was −154 and 38g/d in dry season, and 33 and 119g/d in wet season, for G and GS, respectively. Forage intake was significantly (P<0.05) higher in wet than in dry seasons (99.5 vs. 56.0g DM/kg BW0.75/d, respectively) and that the supplementation did not significantly affect forage intake (75.2 vs. 80.3g DM/kg BW0.75/d, for GS and G, respectively). A significant interaction (P<0.01) between season and supplementation indicated that dry matter digestibility was similar between treatments in the wet season (73.4% vs. 71.0%, for GS and G, respectively) but greater for supplemented animals in the dry season (70.6% vs. 53.8%, respectively). Similar results were observed for organic matter and crude protein digestibilities. The supplementation did not affect the digestibility of neutral detergent fiber in the wet season but improved it in the dry season. A similar trend was observed for the acid detergent fiber digestibility. The results of the total digestible nutrients (TDN) and digestible crude protein (DCP) intake indicated that sheep can meet their energy and protein requirements by only grazing during the wet season, but their maintenance requirements were not met during the dry season. The plasma total protein concentration was higher (P<0.05) in the wet than in the dry season and increased with supplementation. A similar trend was observed for the plasma urea, rumen ammonia and volatile fatty acids (VFAs) concentrations, which were significantly increased in the wet seasons compared to the dry season and were greater for supplemented animals. The opposite was observed for the plasma creatinine levels. Hence, it is concluded that the nutritive value of natural rangelands is higher in wet than in dry seasons and that the concentrate supplementation is essential to maintain animals during the dry season, providing the minimum level of ammonia and VFAs required for maintaining rumen microbial activity and fermentation for grazing sheep in arid region.

Seasonal effect on rumen function in sheep on range in the Accra Plains of Ghana.

This study aimed at investigating the effect of the seasonal decline in quality and availability of feed on rumen function in sheep grazing without supplementation. Effects of season on rumen pH, ammonia nitrogen concentration and rumen degradation of urea-treated rice straw in grazing sheep were determined. Four fistulated Djallonké sheep were added to a group of grazing sheep and used for this study. Rumen contents were sampled for pH and ammonia in the rainy season and in the dry season. Ammoniated rice straw was incubated in the rumen to determine its degradation characteristics. Rumen pH was higher (p < 0.1) in the dry season than in the rainy season. Rumen ammonia nitrogen concentrations on the other hand were similar (p > 0.05) in the two seasons. In sacco dry matter degradation parameters of urea-ammoniated rice straw showed seasonal differences in the soluble (a) and the insoluble but degradable (b) fractions as well as lag time before the start of degradation. It was concluded that despite higher pH in the dry season and similar ammonia nitrogen concentration in the two seasons, rumen degradability of dry matter of urea-treated rice straw in sheep was higher in the rainy season than that in the dry season.

Effects on milk urea concentration, urine output, and drinking water intake from incremental doses of potassium bicarbonate fed to mid-lactation dairy cows

Large variation exists in the potassium content of dairy cow feeds and also within a feed type due to soil type and fertilization. Increased ration K concentration causes a subsequent increase in urinary volume and could be expected to also lower milk urea concentration. Six multiparous mid-lactation Swedish Red dairy cows, all fitted with rumen cannulas, were subjected to 3 different levels of K intake in a Latin square experiment with three 2-wk periods to evaluate the effects on concentrations of milk urea and rumen ammonia, urinary output, and drinking water intake. The treatments were achieved by K supplementation on top of a low-K basal ration fed at individual allowances fixed throughout the experiment. The basal ration, consumed at 20.2kg of dry matter (DM)/d, provided 165g of crude protein/kg of DM and consisted of grass silage, concentrates, and urea in the proportions 39.3:60.0:0.7 on a DM basis. Potassium bicarbonate supplementation was 0, 616, and 1,142g/d, respectively, to give total ration K concentrations that were low (LO; 12g/kg of DM), medium (MED; 23g/kg of DM), or high (HI; 32g/kg of DM). Production and composition of milk was not affected by treatment. A linear effect on milk urea concentration was detected, being 4.48, 4.18, and 3.77mM for LO, MED, and HI, respectively, and a linear tendency for rumen ammonia concentration with 6.65, 6.51, and 5.84mg of NH3-N/dL for LO, MED, and HI, respectively. Milk urea concentration peaked about 3h after the rumen ammonia peak from the morning feeding, at a level 1.3mM over the baseline. Urinary urea excretion declined linearly (105, 103, and 98g of urea-N/d for LO, MED, and HI, respectively). Linear increases occurred in urinary output (0.058±0.001kg of urine/g of K intake; no intercept; coefficient of determination=0.997) and drinking water intake (65.9±2.02 + 0.069±0.004kg of water/g of K intake; coefficient of determination=0.95). Urinary K concentration leveled off at 12.4g/L. Urinary creatinine excretion was not affected by K addition, but allantoin excretion increased linearly by 27% from LO to HI, suggesting increased rumen microbial growth. Rumen pH, acetate proportion of total volatile fatty acids, and digestibility of DM, organic matter, and neutral detergent fiber increased linearly with increasing potassium intake. We concluded that increased ration K concentration lowers milk urea concentration with a magnitude significant for the interpretation of milk urea values, but other sources of variation, such as sampling time relative to feeding, may be even more important.

Whole or ground millet grain provided in two supplementation frequencies for grazing beef cattle: nutritional parameters

The objective of this study was to evaluate the processing of millet grain provided at two supplementation frequencies for grazing beef cattle during the dry season on nutritional parameters. Five rumen-cannulated crossbred steers, with 24 to 26 months of age and average body weight of 428.6±26.06 kg, were assigned to a Latin square design (5 × 5) in a 2 × 2 + 1 factorial arrangement, as follows: two forms of millet grain (whole grains - or ground; WG - GG), two strategies of concentrate supplementation (daily distribution - 7X; or three times a week - 3X) and a control treatment (mineral mixture - MM). Animals were kept in five paddocks of 0.24 ha each with Marandu grass pastures. Concentrate supplements were supplied at 2.00 and 4.66 kg/animal/day for treatments 7X and 3X, respectively. The concentrate supplementation enhanced the intake of total dry matter (DM) and organic matter (OM) and nutrients compared with mineral supplementation. No differences were found between dry matter intake and forage organic matter intake. The values of digestibility coefficients of DM, OM, ether extract, total carbohydrates and non-fiber carbohydrates were increased by concentrate supplementation. Regarding concentrations of rumen ammonia nitrogen, the interactions among time × treatment × day and day × treatment had effects on the measurements of ruminal pH. Plasma urea nitrogen, urinary urea excretion and urinary urea N excretion differed only between MM treatment and the others, with no interference of grain physical form and supplementation frequency on those variables. The millet grain processing does not alter forage intake, but improves digestibility. Daily supplementation increases digestibility of dry matter and neutral detergent fiber.

An evaluation of the performance and efficiency of nitrogen utilization in cattle fed tropical grass pastures with supplementation

The objective of this study was to evaluate the efficiency of nitrogen utilisation (ENU) and animal performance in cattle fed tropical grass pastures and receiving nitrogen supplementation, using a meta-analytical approach. The dataset used to evaluate the ENU was compiled from 10 experiments carried out in Brazil, which were published between 2009 and 2012, totalling 47 treatment means. To compose the dataset for animal performance evaluation, mean treatment values were collected from 44 experiments involving grazing beef cattle, which were published in Brazil from 2001 to 2012, totalling 182 treatment means. The relationships between variables were evaluated using linear or non-linear mixed models, taking into account the random variations among experiments. There was no association between ENU and the balance of nitrogen in the rumen and the efficiency of microbial synthesis in the rumen (P>0.05). The ENU was linearly associated with the dietary content of digestible organic matter in the diet (DOM) and relative production of microbial nitrogen in the rumen (NMICR), which was positive with DOM (P<0.04) and negative with NMICR (P<0.03). The relationships between ENU and dietary crude protein (CP) and the concentration of rumen ammonia nitrogen (RAN) were described using hyperbolic models (P<0.05). The estimated values that correspond to the apparent equilibrium point (i.e., ENU=0) were 108g CP/kg of dry matter and 6.30mg RAN/dL of rumen fluid. There was a positive response on weight gain as the amount of supplement increased (P<0.01). However, this relationship was interactively affected by CP content in the supplement (P<0.02) and in the forage (P<0.01). Through this way, the response of weight gain to supplement is improved by increasing the CP content of the supplement, but decreased as the CP in the forage increases. From this it can be conclude that there is a positive response to nitrogen supplementation with regards to ENU and animal performance. The main benefit of supplementation is the improvement of the nitrogen status in the animal׳s metabolism.

Timing of feeding: a postmodern management strategy to modulate chronophysiological rhythms in rumen fermentation kinetics

Timing of eating is a multiscience that mediates global animal and human physiology and metabolism. The objective is to determine effects of providing a total mixed ration at either 0900 h or 2100 h on rhythmic rumen fermentation and passage kinetics. Four multiparous and four primiparous Holstein cows were used in a cross-over design study with two 6-week periods. Each period had a three-week adaptation period. Rumen ammonia concentrations were lower in primiparous cows fed at 2100 h vs. 0900 h. Rumen propionate was lower and the acetate to propionate ratio was higher in multiparous cows fed at 2100 h vs. 0900 h. Evening-fed cows tended to reach a greater rumen volume than morning-fed cows. Findings suggest that shifting feeding time from 0900 to 2100 h altered rhythmic rumen fermentation kinetics and volume. Therefore, feeding timing can be used as a feasible management strategy to modulate rumen fermentation rhythms in high-producing dairy cows.

Effects of including saponins (Micro-Aid®) on intake, rumen fermentation and digestibility in steers fed low-quality prairie hay

Sixteen ruminally cannulated crossbred steers (529±45kg initial body weight, BW) were used to evaluate in situ dry matter (DM), neutral detergent fiber (aNDF), and N degradation characteristics of low-quality prairie hay, blood urea-N (BUN) and rumen fermentation parameters in steers provided a protein supplement with or without Micro-Aid® (MA; plant derived saponin). Steers were allowed ad libitum access to chopped prairie hay (49g crude protein (CP)/kg DM and 738g aNDF/kg DM) and randomly assigned to one of four treatments: (1) no supplement (C), (2) cottonseed meal and wheat middlings: 920g DM/d (PC; positive control), (3) MA added to PC to supply 1g MA/d (MA1), and (4) MA added to PC to supply 2g MA/d (MA2). Steers were individually supplemented 920g DM once daily at 08:00 along with a vitamin and mineral mix to ensure requirements were met. Orthogonal contrasts were used to determine the effects of protein supplementation, addition of MA and level of MA inclusion. During in situ phase, forage samples were incubated for a 96h period. Protein supplementation increased DM intake (DMI), particulate passage rate (Kp), and rumen digestibility of DM and NDF (P<0.001), but there was no effect on rumen N degradability. The inclusion of MA did not impact DMI in either phase. Compared to PC, MA decreased Kp (27.8 and 22.7g DM/kg/h, respectively; P=0.02), resulting in an increase in rumen aNDF and DM digestibility (P<0.001). However, there was no influence of MA on apparent total tract digestibility in the metabolism phase. Rumen protozoa concentrations were suppressed (P=0.01) with MA inclusion while lactate concentrations and microbial crude protein (MCP) flow to the small intestine were increased (P=0.05). There was no impact on BUN, rumen ammonia, pH, volatile fatty acid (VFA) concentrations or N balance for MA compared to PC diets. Supplementation improved N balance, MCP synthesis and increased total concentrations of VFA and independent acetate and propionate concentrations. In conclusion, including MA in protein supplements increased rumen DM and a NDF digestibility of forage, reduced protozoa concentrations and increased daily outflow of MCP. This is indicative of increased rumen fermentation rate and may ultimately impact animal performance via increased energy and amino acid supply to the small intestine. However, more research is needed to validate this potential impact on animal performance.

English

Effect of the Bt - or conventional cottonseed meal was assessed as well as the performance, fermentation, ciliate protozoa population and microbial enzyme of lambs. Three feed mixture (FM, forage: concentrate ration of 35: 65) contained groundnut oilmeal (GNM), insect protected Btcottonseed meal ( Bt -CM) or conventional whole cottonseed (C-CM) as protein source, were fed for 123 days to the control, C-CM and Bt -CM group of lambs, respectively. Whole seed meal Bt - and C-CM had similar nutrient composition. The Ca was higher while Zn content was lower in C-CM. Both CM had similar metabolizable energy (MJ/kg DM). Lambs of three groups had similar daily gain, DM intake and nutrient digestibility. Rumen fluid pH and TVFA were similar, while ammonia-N (mg/l) was higher (p<0.001) in control lambs. Cottonseed feeding eliminated (p<0.001) rumen protozoa; protozoa were 101.1, 59.0 and 39.6 ×104/ ml in rumen fluid respectively in control, C-CM and Bt -CM diet fed lambs. Rumen enzymes activities of xyalanase, β-glucosidase and β-xylosidase were similar, while Bt -CM feeding reduced (p=0.010) carboxymethyl cellulase (CMCase) activity by 47% and increased proteases activity by 22%. The study concludes that inclusion of Bt-CM produced pronounced defaunation with reduced rumen ammonia concentrations, which improved daily gain. Therefore, Bt -CM can be incorporated at 180 g/kg in lamb diet. Keywords: Cottonseed, genetically modified feed, performance, fermentation, rumen enzymes African Journal of Biotechnology , Vol. 13(3), pp. 509-522, 15 January, 2014

Effects of Two Sources of Tannins (Quercus L. and Vaccinium Vitis Idaea L.) on Rumen Microbial Fermentation: an in Vitro Study

The aim of the experiment was to determine the effect of different sources of tannins on the in vitro rumen fermentation with focus on methane production. In the experiment, a rumen simulation system (RUSITEC) equipped with 4 fermenters (1 L) was used in three replicated runs (6 d of adaptation and 4 d of sampling) to study the effects of Quercus cortex extract (QC), Vaccinium vitis idaea (VVI) dried leaf extract and a mixture of VVI/QC on rumen microbial fermentation. Fermenters were fed 10.9 g/d of dry matter (DM) of a 600:400 forage:concentrate diet. Treatments were control, QC (2.725 mL), VVI leaves 0.080 g) and mixture of QC/VVI (1.362 mL+0.040 g) and were randomly assigned to fermenters within periods. The equivalent of 2.5 g of tannins/kg dietary DM from three sources of tannins was evaluated. All tannin sources decreased CH4 and ammonia concentrations, as well as protozoa and methanogen counts (P<0.001). Vaccinium vitis idaea and QC/VVI tended (P=0.005) to reduce the acetate to propionate ratio. There were no changes in nutrient digestion. Results suggest that these sources of tannins, especially VVI have the potential to reduce rumen CH4 production and ammonia concentration without negative effects on in vitro DM digestibility, total volatile fatty acids and pH.

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.

Effect of different levels of saturated solution of calcium chloride in the preparation of calcium salt of fatty acid and its effect on rumen protozoa, pH and ammonia nitrogen

Calcium salt of fatty acid was prepared by adding 3 different levels of saturated solution of calcium chloride (CaCl2) to soybean oil. It was found that fat content was not significantly affected by calcium chloride. However, calcium chloride had significant effect on other parameters like dry matter, fat, ash and sodium. The highest calcium and fat was obtained when 3.5 parts CaCl2 were added (p&lt;0.01). It was also observed that “sun drying” and “drying at room temperature” had no significant effect on any parameter except dry matter content. Calcium salt of fatty acid had significant anti-protozoal effect (p&lt;0.01) in sheep. Treated group showed reduced protozoal number without affecting the rumen pH and rumen ammonia nitrogen. It was also found that the number of rumen protozoa in rumen liquor was less at 12:00 p.m. than that at 3:30 p.m. when sheep were fed 3% calcium salt. DOI: http://dx.doi.org/10.3329/bjas.v42i2.18489Bang. J. Anim. Sci. 2013. 42 (2): 109-113

Urea-N recycling in lactating dairy cows fed diets with 2 different levels of dietary crude protein and starch with or without monensin

Rumensin (monensin; Elanco Animal Health, Greenfield, IN) has been shown to reduce ammonia production and microbial populations in vitro; thus, it would be assumed to reduce ruminal ammonia production and subsequent urea production and consequently affect urea recycling. The objective of this experiment was to determine the effects of 2 levels of dietary crude protein (CP) and 2 levels of starch, with and without Rumensin on urea-N recycling in lactating dairy cattle. Twelve lactating Holstein dairy cows (107±21d in milk, 647kg ± 37kg of body weight) were fed diets characterized as having high (16.7%) or low (15.3%) CP with or without Rumensin, while dietary starch levels (23 vs. 29%) were varied between 2 feeding periods with at least 7d of adaptation between measurements. Cows assigned to high or low protein and to Rumensin or no Rumensin remained on those treatments to avoid carryover effects. The diets consisted of approximately 40% corn silage, 20% alfalfa hay, and 40% concentrate mix specific to the treatment diets, with 0.5kg of wheat straw added to the high starch diets to enhance effective fiber intake. The diets were formulated using Cornell Net Carbohydrate and Protein System (version 6.1), and the low-protein diets were formulated to be deficient for rumen ammonia to create conditions that should enhance the demand for urea recycling. The high-protein diets were formulated to be positive for both rumen ammonia and metabolizable protein. Rumen fluid, urine, feces, and milk samples were collected before and after a 72-h continuous jugular infusion of 15N15N-urea. Total urine and feces were collected during the urea infusions for N balance measurements. Milk yield and dry matter intake were improved in cows fed the higher level of dietary CP and by Rumensin. Ruminal ammonia and milk and plasma urea nitrogen concentrations corresponded to dietary CP concentration. As has been shown in vitro, Rumensin reduced rumen ammonia concentration by approximately 23% but did not affect urea entry rate or gastrointestinal entry rate. Urea entry rate averaged approximately 57% of total N intake for cattle with and without Rumensin, and gastrointestinal rate was similar at 43 and 42% of N intake for cattle fed and not fed Rumensin, respectively. The cattle fed the high-protein diet had a 25% increase in urea entry rate and no effect of starch level was observed for any recycling parameters. Contrary to our hypothesis, Rumensin did not alter urea production and recycling.

Effects of slow-release urea and molasses on ruminal metabolism of lambs fed with low-quality tropical forage

The effects of two sources of slow-release urea (SRU) with a source of soluble carbohydrates on ruminal fermentation in lambs fed with a low-quality forage hay were evaluated. Optigen is a commercial source of slow-release urea, whereas Surelease is an ethyl cellulose-coated urea prepared in the Laboratorio de Farmacotecnia at the Metropolitan Autonomous University. Five Pelibuey lambs cannulated in the rumen and duodenum (24.8±0.4kg BW) were used in a Latin Square design. Lambs were fed a basal diet that consisted of Brachiaria brizantha hay and concentrate (ratio 67:33) with the following treatments: (1) feed-grade urea; (2) Surelease-coated urea (SRU-S); (3) SRU-S+molasses; (4) SRU Optigen (OPT); and (5) OPT+molasses. All sources of urea were dosed daily intra-ruminally (0.6g/kg/BW), and molasses was fed at 1.2g/kg BW. Compared to feed-grade urea, both sources of SRU decreased ruminal pH between 3 and 6h after dosing (P<0.05). At 3 and 9h after dosing and at 15 and 21h, both sources of slow-release urea reduced the rumen ammonia compared to urea (P<0.05). The two sources of slow-release urea did not improve the total tract or rumen digestibility of dry matter (DM) and neutral detergent fiber (NDF) or the rate of microbial protein synthesis in growing lambs fed low quality forage.

Evaluation of Olive and Palm Byproducts in Feeding Camels

Metabolism trials were carried out using four mature males of Sudanese camels; Camelius dromedaries to evaluate the nutritive value of date stone (DS) and olive cake (OC), palm leaves (PL) and barley grains (BG) or their mixture. Results indicated that barley grains showed significantly (p<0.05) higher digestibility and nutritive value in all nutrients except for EE and ADF compared with either olive cake or date stone. In addition, DS showed better digestibility in all nutrients compared with OC except for EE digestibility. The ration contained BG plus DS recorded the highest digestibility for DM, OM, CP, CF and NFE. While, the ration contained BG plus OC recorded higher digestibility for NDF and ADF. No significant differences were detected in dry matter intake expressed as DMI g/W by camels fed different either tested feeds or rations. 0.75 The water intake increased with animals fed DS being 8.42 L compared with BG and OC being 7.58 and 6.92 L, respectively. Also, results showed that animals consumed the ration contained BG plus DS recorded the highest water intake being 8.33 L. Feeding on BG led up to significant (p<0.05) decrease in pH values compared with other feeds after 3 and 5 h. No significant differences in ammonia nitrogen concentration at 5 h post feeding with all feeds. The BG plus DS mixture gave the lowest concentration of rumen ammonia content at the three times. While, BG with PL mixture showed the highest value of rumen ammonia content at the three times. It could be concluded that date stone and olive cake used to feed camel as substitution of barley grains without any adverse effect.

Effects of urea supplementation on nutrient digestibility, nitrogen utilisation and rumen fermentation in sheep fed diets containing dates

Summary: The aim of the study was to determine the influence of increasing levels of urea (i.e., 0 (U0); 10 (U10); and 15 (U15) g kg–1 of concentrate) in sheep fed diets containing dates (local name: Azzawi), on nutrient intake and digestibility, N utilisation and ruminal fermentation. To maintain iso-nitrogenous and iso-metabolisable energy diets, the dates were added with increasing levels of urea. Sheep were fed a 400:600 (dry matter (DM) basis) concentrate:berseem hay (Trifolium alexandrinum) diet. Twelve Barki sheep (53.8±1.95kg body weight) with three/diet were used in a randomised block design to determine digestibility and N balance, while four ruminally cannulated Barki sheep (56.6±2.15kg body weight) were used in a 3×3 Latin square design to determine rumen function. Experimental periods were 22 days with the first 15 days for adaptation. The calculated metabolisable energy (MJ kg–1 DM) and actual crude protein (CP; g kg–1 DM) contents were 12.17 and 156.1, 12.69 and 158.2 and 12.60 and 154.8, for the U0, U10 and U15 diets, respectively. Increased urea feeding increased (P<0.05) digestibility of DM, organic matter (OM) and CP. Rumen ammonia N concentrations, allantoin in urine and the resultant microbial N supply increased linearly (P<0.05), as did the total ruminal volatile fatty acid concentrations. Results suggest that urea supplementation to sheep diets containing dates improved DM, OM and CP digestibility and substantially increased rumen microbial growth as well as ruminal fermentation function.

Short communication: Effects of level of rumen-degradable protein and corn distillers grains in corn silage-based diets on milk production and ruminal fermentation in lactating dairy cows

Two of the potential obstacles precluding inclusion of higher levels of dry distillers grains with solubles (DDGS) in corn-based dairy cow diets are the low levels of rumen-degradable protein (RDP) and the fatty acid content and composition of DDGS. Therefore, the objective of this experiment was to evaluate the production and rumen responses to dietary alterations in the level of RDP and DDGS for dairy cows fed a high corn silage diet. The experimental design was a replicated 4×4 Latin square with 21-d periods: 14 d of adaptation and 7 d of sampling; 16 uncannulated cows and 4 ruminally cannulated cows were blocked and assigned randomly to treatment sequences. Rations were provided as total mixed rations and were formulated to be high or low in RDP, with or without DDGS replacing soybean-based concentrates: high RDP, no DDGS (HRDP0); low RDP, no DDGS (LRDP0); low RDP, 10% DDGS; and low RDP, 20% DDGS. Body weight (696kg) and dry matter intake (26.6 kg/d) were not affected by treatment. Rumen ammonia concentration was greater for HRDP0 than LRDP0, but was unaffected by level of DDGS inclusion. The mean and minimum rumen pH and time pH was <5.5 were not different between diets. Milk production tended to be lower for cows fed HRDP0 than LRDP0 and tended to be linearly reduced as DDGS inclusion increased. Milk protein yield tended to be greater for cows fed LRDP0 than HRDP0, but was unaffected by DDGS level. Milk fat production, concentration, and fat-corrected milk were linearly reduced by increasing levels of DDGS. Based on these results, feeding DDGS at 20% of diet dry matter is not recommended for diets based on high corn silage.

The effects of crude protein concentration and slow release urea on nitrogen metabolism in Holstein steers

This experiment was conducted to determine the effects of slow release urea (SRU) and its interaction with crude protein (CP) level in the diet on N metabolism in Holstein steers. Eight rumen-cannulated Holstein steers (body weight 265 ± 18 kg) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial treatment structure. Treatment factors were the CP level in the diet, 10.9% versus 12.1% CP, and the non-protein nitrogen source used, urea versus SRU. Total collection of urine and faeces for 7 days allowed the estimation of N retention and diet digestibility. In addition, blood and rumen sampling allowed estimation of rumen fermentation and blood N profiles. Decreasing CP intake from 12.1% to 10.9% reduced urinary N output, but also reduced diet digestibility and N retention. When compared to urea, SRU did not alter N retention, but reduced ruminal ammonia and plasma urea concentrations. Although SRU did not improve N retention at either CP level, rumen ammonia and plasma urea concentrations were reduced, which may indicate that SRU may carry a lower risk for toxicity when compared to urea when fed at higher dietary concentrations.

Effects of exogenous enzymes on nutrient digestibility, ruminal fermentation and growth performance in beef steers

Forty crossbred steers (Baladi×Friesian, average BW 153±5.14kg) were used to evaluate the effects of exogenous enzyme (ENZ) addition on nutrient intake, digestion, ruminal fermentation and feed conversion in beef steers. Steers were randomly assigned to two groups of 20 animals and fed individually a total mixed ration (TMR) without (CTRL) or with addition of 40g/hd/d of an enzyme mixture (ZADO®). The ENZ mixture was added for 220 days and in vivo apparent digestibility was measured on days 210–220. Enzyme addition did not affect (P=0.1) DM intake, whereas it increased (P<0.05) total tract apparent digestibility of all nutrients. The magnitude of improvement in digestibility varied among nutrients, with the highest improvement occurring in digestibility of NDF and ADF (21.8% and 26.7%, respectively). Addition of ENZ also increased (P<0.05) concentrations of rumen ammonia N and total short chain fatty acids (SCFA) before and 3h post-feeding. Allantoin concentration total purine derivates were increased (P=0.04) with enzyme addition while uric acid was not affected (P=0.05). Live-weight gain was also higher (P<0.01) in steers supplemented with ENZ. In conclusion, adding the exogenous enzyme product increased live-weight gain by 16% due to increased nutrient digestibility.

Methane production and digestion of different physical forms of rapeseed as fat supplements in dairy cows

The purpose of this experiment was to study the effect of the physical form of rapeseed fat on methane (CH4) mitigation properties, feed digestion, and rumen fermentation. Four lactating ruminal-, duodenal-, and ileal-cannulated Danish Holstein dairy cows (143 d in milk, milk yield of 34.3kg) were submitted to a 4×4 Latin square design with 4 rations: 1 control with rapeseed meal (low-fat, CON) and 3 fat-supplemented rations with either rapeseed cake (RSC), whole cracked rapeseed (WCR), or rapeseed oil (RSO). Dietary fat concentrations were 3.5 in CON, 5.5 in RSC, 6.2 in WCR, and 6.5% in RSO. The amount of fat-free rapeseed was kept constant for all rations. The forage consisted of corn silage and grass silage and the forage to concentrate ratio was 50:50 on a dry matter basis. Diurnal samples of duodenal and ileal digesta and feces were compiled. The methane production was measured for 4 d in open-circuit respiration chambers. Additional fat reduced the CH4 production per kilogram of dry matter intake and as a proportion of the gross energy intake by 11 and 14%, respectively. Neither the total tract nor the rumen digestibility of organic matter (OM) or neutral detergent fiber were significantly affected by the treatment. Relating the CH4 production to the total-tract digested OM showed a tendency to decrease CH4 per kilogram of digested OM for fat-supplemented rations versus CON. The acetate to propionate ratio was not affected for RSC and WCR but was increased for RSO compared with CON. The rumen ammonia concentration was not affected by the ration. The milk and energy-corrected milk yields were unaffected by the fat supplementation. In conclusion, rapeseed is an appropriate fat source to reduce the enteric CH4 production without affecting neutral detergent fiber digestion or milk production. The physical form of fat did not influence the CH4-reducing effect of rapeseed fat. However, differences in the volatile fatty acid pattern indicate that different mechanisms may be involved.

Effect of compound feed pelleting and die diameter on rumen fermentation in beef cattle fed high concentrate diets

The effect of feeding a compound feed as meal (M) or pelleted at 3.5 (P3.5) or 10 (P10) mm i.d. on feed intake pattern and rumen fermentation in growing calves was investigated. Compound feeds were fed ad libitum with barley straw to six 3-mo-old rumen cannulated calves in a double 3×3 Latin square arrangement. In a first 9-wk phase (I) free access to concentrate was allowed, whereas in a second 6-wk phase (II) access was restricted to 09:00h to 11:30h and 17:00h to 19:30h. Rumen samples were collected on two non-consecutive days at 08:30h, 13:00h and 17:00h. Pelleting increased the degree of starch gelatinization from 0.113 in M to 0.205 and 0.154, in P3.5 and P10. In both phases, P10 slowed consumption of concentrate during morning feeding (P<0.01), although treatments did not affect total daily concentrate intake (97gDM/kgLW0.75 and 82gDM/kgLW0.75) in phases I and II. In phase I, pH before morning distribution was lower than in phase II (6.5 versus 7.2). Four hours after feeding, there was a pH drop (P<0.001), which was higher in phase II (1.5 units) than in phase I (0.7 units), in line with a higher concentrate intake (4.10kg versus 1.89kg). Calves fed P3.5 tended (P=0.052) to a lower pH than those on M in phase I, and those fed P10 had the least decrease in pH after feeding. No pH differences occurred between treatments in phase II, although pH recovery from 4 to 8h after feeding tended to be more (P=0.073) for P10. Rumen lactic acid concentration increased after feeding (P<0.05 and P<0.001) in phases I and II, reaching 45.7mg/l and 39.6mg/l, respectively. In phase II, P3.5 animals reached a higher (P<0.01) concentration than M and P10 animals. Rumen ammonia concentration decreased (P<0.001) after feeding, reaching the lowest values 4h later (23.3mg/l and 13.6mg/l in phases I and II). P3.5 showed lower ammonia concentration than M in phase I (P<0.05). Total volatile fatty acid (VFA) concentration increased (P<0.001) after feeding in both phases, decreasing the acetic to propionic ratio (P<0.001). In phase I, calves fed M tended (P=0.074) to have lower total VFA rumen concentration and higher acetic to propionic ratio (P<0.01) than those fed pellets. Results suggest that with pelleting at 3.5mm, increased ruminal fermentation rate dominates regulation of substrate delivery and results in lower pH values that could eventually translate into higher risk of acidosis compared with unprocessed meal. Increasing the pellet diameter to 10mm may decrease the rate of fermentation through a homogeneous daily intake pattern, without affecting total intake, even under conditions of restricted feeding.